#191 
 
Changes to Approved NADAs  
New NADAs 
vs. 
Category II Supplemental NADAs 
 
Guidance for Industry 
 
This version of the guidance replaces the version made available February 2020.  This revision 
reorganizes Appendix III for better clarity. 
 
Submit comments on this guidance at any time.  Submit electronic comments to 
https://www.regulations.gov.  Submit written comments to the Dockets Management Staff 
(HFA-305), Food and Drug Administration, 5630 Fishers Lane, Rm. 1061, Rockville, MD  
20852.  All comments should be identified with the docket number FDA-2008-D-0614. 
 
For further information regarding this document, contact AskCVM@fda.hhs.gov. 
 
Additional copies of this guidance document may be requested from the Policy and Regulations 
Staff (HFV-6), Center for Veterinary Medicine, Food and Drug Administration, 7500 Standish 
Place, Rockville MD 20855, and may be viewed on the Internet at either 
https://www.fda.gov/animal-veterinary or https://www.regulations.gov. 
 
 
 
 
U.S. Department of Health and Human Services 
Food and Drug Administration 
Center for Veterinary Medicine (CVM) 
August 2020    Contains Nonbinding Recommendations 
 
Table of Contents 
 
I.  Introduction ....................................................................................................................... 3 
II.  Background ....................................................................................................................... 3 
III.  Definitions .......................................................................................................................... 5 
IV.  New NADA or Category II Supplemental NADA  Which is Best? ............................ 6 
A.  New Active Pharmaceutical Ingredient (API)  Submit as New NADA ............ 7 
B.  New Dosage Form  Submit as New NADA .......................................................... 8 
C.  New Major Route of Administration  Submit as New NADA ........................... 9 
D.  Adding Target Animals  Submit as a Category II Supplemental NADA ....... 10 
E.  Adding or Changing Doses  Submit as a Category II Supplemental NADA . 11 
F.  Changing Dosing Schedule  Submit as a Category II Supplemental NADA . 11 
G.  Adding Indications  Submit as a Category II Supplemental NADA .............. 11 
H.  Changing (Rx, OTC, VFD) Status  Submit as a Category II Supplemental 
NADA ....................................................................................................................... 12 
I.  Replacing, Adding, Deleting, or Changing Concentrations of Inactive 
Ingredients ............................................................................................................... 12 
J.  Changing Concentrations of Active Ingredients .................................................. 13 
K.  Multiple Changes ..................................................................................................... 13 
V.  Conclusions ...................................................................................................................... 16 
Appendix I.  Examples of Dosage Forms of New Animal Drugs ............................................ 17 
Appendix II.  Examples of Routes of Administration for New Animal Drugs ...................... 21 
Appendix III.  Target Animal Classes of Major Food Animals ............................................. 23 
  2  Contains Nonbinding Recommendations 
 
Changes to Approved NADAs  
New NADAs 
vs. 
Category II Supplemental NADAs 
 
Guidance for Industry 
 
This guidance represents the current thinking of the Food and Drug Administration (FDA or 
Agency) on this topic.  It does not establish any rights for any person and is not binding on FDA 
or the public.  You can use an alternative approach if it satisfies the requirements of the 
applicable statutes and regulations.  To discuss an alternative approach, contact the FDA staff 
responsible for this guidance as listed on the title page. 
 
I.  Introduction 
 
This guidance is intended to assist sponsors who wish to apply for approval of changes to 
approved new animal drugs that require FDA to reevaluate safety and/or effectiveness data.  The 
guidance explains how the Office of New Animal Drug Evaluation (ONADE) categorizes 
possible changes to approved new animal drugs that require reevaluation of safety and/or 
effectiveness data and explains which administrative vehicle  a new original new animal drug 
application (new NADA) or a Category II supplemental application to the original new animal 
drug application (Category II supplemental NADA)  a sponsor should use when applying for 
approval of these changes.1  The goal of this guidance is to create greater consistency in how 
such applications are handled by sponsors and by ONADE. 
 
The recommendations in this guidance do not apply to changes to intentional genomic alterations 
in animals, regardless of whether they are heritable or non-heritable (e.g., gene therapies).  For 
inquiries regarding such products, please contact AskCVM@fda.hhs.gov. 
 
In general, FDAs guidance documents do not establish legally enforceable responsibilities.  
Instead, guidances describe the Agencys current thinking on a topic and should be viewed only 
as recommendations, unless specific regulatory or statutory requirements are cited.  The use of 
the word should in Agency guidances means that something is suggested or recommended, but 
not required. 
 
II.  Background 
 
In the past, applications for changes to approved new animal drugs may have been handled 
inconsistently by sponsors and the Agency.  For example, in some instances, a sponsor may have 
                                                 
1 This guidance does not apply to applications for conditional approvals under section 571 of the Federal Food, 
Drug, and Cosmetic Act (FFDCA). 
  3  Contains Nonbinding Recommendations 
filed an application for a specific change as a new NADA; in other instances, an application for a 
similar change was filed as a supplemental NADA.  Inconsistency in handling such applications 
has been confusing for sponsors and for ONADE, particularly when reviewing and referencing 
the history of specific NADAs.  This guidance is intended to improve consistency in the way 
applications for changes are handled.  For these reasons, we believe that consistent handling of 
these types of applications also will help maintain clarity in the administrative record, which is 
an important part of protecting the public health. 
 
For purposes of this guidance, a new animal drug is defined as any drug intended for use for 
animals other than humans, the composition of which is such that such drug is not generally 
recognized as safe and effective for use under the conditions prescribed, recommended, or 
suggested in the labeling of the drug (21 U.S.C.  321(v); 21 CFR 510.3(g)(1)).  A new animal 
drug as referenced in this document consists of the final dosage form.  Before a new NADA can 
be approved by FDA, the submitted study data, which are reviewed by the Agency, must 
demonstrate that the new animal drug is safe and effective for use (21 U.S.C.  360b(d)(1); 21 
CFR 514.1(b)(8)). 
 
When proposing a change to an approved new animal drug that may affect the safety and/or 
effectiveness of the drug, such changes generally must be submitted to FDA either as a new 
NADA or a supplemental application to the original NADA.  Category II supplemental NADAs 
are the type of supplement that is used to propose changes that may require a reevaluation of 
certain safety or effectiveness data in the parent application.  Specific changes meeting the 
requirements for a Category II supplemental NADA are described in 21 CFR 514.106(b)(2).  
This guidance provides examples and makes specific recommendations about when a change to 
an approved NADA that requires FDA to review safety and/or effectiveness data should be 
submitted as a new NADA and when such a change should be submitted as a Category II 
supplemental NADA.  In addition, the guidance addresses how to handle submissions relating to 
certain types of proposed changes at the investigational stage. 
 
Other guidances are relevant to this discussion.  For example, CVMs guidance for industry 
(GFI) #82, Development of Supplemental Applications for Approved New Animal Drugs,2 
provides limited guidance on how to determine when changes to approved new animal drugs 
should be submitted as a Category I or Category II supplemental NADA (based on 21 CFR 
514.106) or as a new NADA.  GFI #82 primarily outlines the general information that should be 
included in each technical section when submitting a supplemental NADA.  CVM GFI #83, 
Chemistry, Manufacturing and Controls Changes to an Approved NADA or ANADA,3 also 
may be of interest. 
 
This guidance makes recommendations that apply only to changes to approved new animal drugs 
that require the review of safety and/or effectiveness data.  This guidance expands upon CVMs 
GFI #82 and more clearly defines which changes in approved new animal drugs will result in a 
new NADA or a Category II supplemental NADA.  Furthermore, this guidance also addresses 
                                                 
2 https://www.fda.gov/media/70308/download 
3 https://www.fda.gov/media/70323/download 
  4  Contains Nonbinding Recommendations 
appropriate submissions at the investigational stage.  The recommendations in this guidance 
apply to any study (e.g., dose characterization, dose confirmation, target animal safety, 
palatability, residue, toxicology) submitted to FDA to fulfill effectiveness and/or safety technical 
sections for new animal drugs.  Except for some noted exceptions, the recommendations 
generally are similar to those in CVMs GFI #82.4 
Specifically, this guidance and its appendices discuss the following: 
 When to submit an individual change to an approved NADA as a new NADA or as a 
Category II supplement to the original application, assuming nothing else about the new 
animal drug product is changed.
 Whether multiple concurrent changes to an approved NADA should be submitted as one 
or separate applications, and whether each of these applications should be a new NADA 
or a Category II supplemental NADA.
 How to handle submissions at the investigational stages of development (i.e., submissions 
to investigational new animal drug files (INADs)) relating to proposed changes in 
approved new animal drugs.
 Definitions for various dosage forms and routes of administration for new animal drugs, 
  as well as information about the target animal classes of major food animals. 
III.  Definitions
For purposes of this guidance, the following definitions apply: 
Active Pharmaceutical Ingredient (API) is the substance or mixture of substances in a drug 
product that is intended to furnish the direct effect in the diagnosis, cure, mitigation, treatment, 
or prevention of disease or to affect the structure or any function of the body.  For the purposes 
of this document, the terms active ingredient and API are considered synonymous. 
Dosage form is the pharmaceutical product type, or physical form, of an API as produced or 
given to the animal (Appendix I).  A new dosage form contains the same API as included in an 
existing new animal drug previously approved by FDA but as a different pharmaceutical product 
type (see GFI #74, Stability Testing of New Veterinary Dosage Forms, International 
Cooperation on Harmonisation of Technical Requirements for Registration of Veterinary 
Medicinal Products [VICH] GL45).  Dosage forms are distinct from routes of administration 
(Appendix II). 
4 The recommendations in this guidance are consistent with the guidance Submitting Separate Marketing 
Applications and Clinical Data for Purposes of Assessing User Fees, issued by FDAs Center for Drug Evaluation 
and Research (CDER) and Center for Biologics Evaluation and Research (CBER), which addresses how sponsors 
should handle differences in human drugs and biologics when submitting an original application and when wishing 
to make changes to an approved product.  (https://www.fda.gov/media/72397/download  
5 https://www.fda.gov/media/70255/download 
5  Contains Nonbinding Recommendations 
A new animal drug is defined, in part, as any drug intended for use for animals other than man, 
the composition of which is such that such drug is not generally recognized as safe and effective 
for use under the conditions prescribed, recommended, or suggested in the labeling of the drug 
(21 U.S.C  321(v); 21 CFR 510.3(g)(1)).  All such drugs are called new animal drugs.  A new 
animal drug as referenced in this document consists of the final dosage form. 
 
In addition, we note that: 
 
A Category I supplemental NADA ordinarily does not require a reevaluation of any of the 
safety or effectiveness data in the parent application (21 CFR 514.106(b)(1)).6  
 
A Category II supplemental NADA may require a reevaluation of certain safety or 
effectiveness data in the parent application (21 CFR 514.106(b)(2)). 
 
IV.  New NADA or Category II Supplemental NADA  Which is Best? 
 
In the following sections, we discuss when you should submit a new NADA and when you 
should submit a Category II supplemental NADA if you are requesting changes to an approved 
new animal drug that require review of safety and/or effectiveness data.  We also discuss how to 
handle these types of changes at the investigational stage (i.e., INAD submissions).  In addition, 
with regard to requests for multiple concurrent changes to an approved new animal drug, we 
offer examples to help determine whether such changes should be submitted as a single 
application or multiple applications, and how to handle these requests at the investigational 
stage.  Before discussing specific cases, we note the following important considerations: 
 
1.  When you submit a new NADA or Category II supplemental NADA, you must own or 
have a right of reference7 to the data that support the application.  If a sponsor does not 
own or have a right of reference to data supporting an application, CVM will find the 
application to be deficient or incomplete.  If you transfer ownership or lose the right of 
reference, you should consider the possible effect on pending, and future, submissions 
and applications.  If you withdraw an approved NADA, you may no longer reference the 
data in that application (21 CFR 514.115(d)). 
2.  The sponsor's decision about whether to file a new NADA versus a Category II 
supplemental NADA ordinarily will not alter CVMs decisions as to what specific safety 
and/or effectiveness data will be needed to support the approval of an application. 
 
Table 1 summarizes whether a new NADA or a Category II supplemental NADA would be 
appropriate for specific changes to an approved new animal drug that require review of safety 
and/or effectiveness data.  The subsequent sections of this document provide details on handling 
each specific change. 
 
                                                 
6 Because this guidance is only intended to address changes to approved new animal drugs that would generally 
require FDA to reevaluate safety and/or effectiveness data in the parent application, Category I supplemental 
NADAs are outside the scope of this guidance. 
7 21 CFR 514.1(a) 
  6  Contains Nonbinding Recommendations 
Table 1.  Summary of when to file a new NADA or a Category II supplemental NADA. 
Proposed Change to Your  Submit as  Submit as Cat. II  Contact ONADE 
Approved New Animal  New NADA  Supplemental  for 
Drug  NADA  Recommendations 
New API  Yes  No  No 
New Dosage Form  Yes  No  No 
Variation of Previously  No  Yes  No 
Approved Dosage 
Form 
New Major Route of  Yes  No  No 
Administration 
Variation of Previously  No  Yes  No 
Approved Major Route 
of Administration 
Add Target Animal  No  Yes  No 
Add/Change Dose  No  Yes  No 
Change Dosing Schedule  No  Yes  No 
Add Indications No  Yes  No 
Change Rx/OTC/VFD  No  Yes  No 
Status 
Replace, Add, Delete, or  No  No  Yes 
Change Concentration of 
Inactive Ingredient 
Change Concentration of  No  No  Yes 
Active Ingredients 
Multiple Changes  No  No  Yes 
A.  New Active Pharmaceutical Ingredient (API)  Submit as New NADA
If you are submitting a change that will create a new active pharmaceutical ingredient (API), we 
recommend you submit a new NADA.  As noted previously, a new animal drug is any drug 
intended for use for animals other than man, the composition of which is such that such drug is 
not generally recognized as safe and effective for use under the conditions prescribed, 
recommended, or suggested in the labeling of the drug (21 U.S.C  321(v); 21 CFR 510.3(g)(1)).   
Changes to the API drug molecule, as well as a change to the salt, ester, or enantiomer/racemic 
mixture of an existing API drug molecule, are considered to be a change in the API, which is a 
7  Contains Nonbinding Recommendations 
basis for the newness of an animal drug (21 CFR 510.3(i)(1)).  In such cases, a new NADA 
should be submitted, not a Category II supplemental NADA.8, 9 
 
Similarly, a new combination of two or more active ingredients for use in animals should be 
submitted as a new NADA, not a Category II supplemental NADA. 
 
During the investigational phase of development, sponsors of new animal drugs should establish 
separate investigational new animal drug files (INADs) for new animal drugs containing 
different APIs. 
 
B.  New Dosage Form  Submit as New NADA 
 
New dosage forms of the same API typically result in delivery of the drug by a different route of 
administration or a different delivery system, which is another basis for the newness of an 
animal drug (21 CFR 510.3(i)(6)).  Thus, your application for a different dosage form of an API 
for which you have already received approval for use in animals should be submitted as a new 
NADA, not a Category II supplemental NADA.  Although a Category II supplemental NADA 
does provide for a change in the...composition of the final product and a change in the 
treatment regimen (schedule of dosing) (21 CFR 514.106(b)(2)(i) and (iv), respectively), CVM 
considers these situations to pertain to changes in composition that do not alter the dosage form 
of the new animal drug. 
 
Special considerations may be appropriate for new animal drugs approved as medicated articles 
and feeds (21 CFR part 558).  An application may be submitted for a new physical form of a 
Type A medicated article (e.g., liquid formulation versus dry formulation).  If it is determined 
that the new physical form and inactive ingredient composition do not significantly affect the 
safety and effectiveness of the API (similar to some changes in inactive ingredients in other new 
animal drugs as described in section IV. I. Replacing, Adding, Deleting, or Changing 
Concentrations of Inactive Ingredients), the application should be submitted as a Category II 
supplemental NADA.  However, if changes in the physical form and inactive ingredient 
composition significantly affect safety and/or effectiveness of the API compared to the 
previously approved Type A medicated article, the application should be submitted as a new 
NADA, not a Category II supplemental NADA (see section IV. I. Replacing, Adding, Deleting, 
or Changing Concentrations of Inactive Ingredients).  Consult with ONADE to determine 
whether the application should be submitted as a new NADA or a Category II supplemental 
NADA.  It may be necessary for CVM to review safety and effectiveness information relevant to 
                                                 
8 In its October 17, 1990, policy letter regarding the implementation of the Generic Animal Drug and Patent Term 
Restoration Act (GADPTRA), CVM stated that a product that contains a different salt or ester form of the same drug 
in the finished new animal drug product is considered to contain a different active ingredient. 
9 CVM GFI #185 (VICH GL43), Target Animal Safety for Veterinary Pharmaceutical Products 
(https://www.fda.gov/media/70438/download), indicates: Margin of safety studies are generally required for new 
salts or formulations of an API.  Exceptions should be justified, for example, on the basis of known toxicology and 
target animal safety profiles for the API, widespread clinical use of existing products, and/or where the systemic or 
local exposure (as applicable) of the new product is proven to be equivalent to or less than that of the existing 
product. 
  8  Contains Nonbinding Recommendations 
the proposed change during the investigational (INAD) process to determine the appropriate 
administrative vehicle. 
 
Applications for new free choice or liquid Medicated Type B and C feeds (21 CFR 510.455 and 
21 CFR 558.5) derived from the same approved Type A Medicated Article should be submitted 
as Category II supplemental NADAs to the affected Type A Medicated Article NADA. 
 
To improve clarity of the administrative record, sponsors of new animal drugs containing the 
same API should establish a separate INAD for each dosage form of the new animal drug. 
 
Appendix I provides the names and definitions of dosage forms of currently approved new 
animal drugs (21 CFR parts 520, 522, 524, 526, 529, and 558), including medicated articles and 
feeds.  Dosage forms are distinguished from routes of administration (Appendix II, see below).  
In general, if you intend to add a dosage form or change the dosage form of your approved API 
to any other dosage form listed in the far-left column of the table in Appendix I, the application 
should be submitted as an NADA.  There are variations of specific dosage forms (second 
column), such as Bolus and Tablet, Coated within Tablet, Compressed.  If you intend to add or 
change from one variation to another within the same dosage form of an approved API (e.g., 
from capsule to coated capsule), the application should be submitted as a Category II 
supplemental NADA. 
 
Appendix I is not intended to include all possible dosage forms of new animal drugs.  Contact 
ONADE10 on how to handle applications for dosage forms not listed. 
 
C.  New Major Route of Administration  Submit as New NADA 
 
CVM considers adding or changing to a different major route of administration to be a change to 
the newness of a ... method ... of administration or application... (21 CFR 510.3(i)(6)).  Thus, 
your application for approval of a different major route of administration for a new animal drug 
for which you have previously received approval should be submitted as a new NADA, not a 
Category II supplemental NADA. 
 
To improve clarity of the administrative record, sponsors of a new animal drug should establish 
separate INADs for different major routes of administration of the drug product. 
 
Appendix II describes some major routes of administration for new animal drugs.  In general, if 
you intend to add or change a major route of administration of your approved new animal drug to 
any other major route of administration specified in Appendix II, you should submit the 
application as a new NADA.  There are variations within some major routes of administration, 
such as Intramuscular and Subcutaneous within Injection.  An application to add or change a 
variation within a major route of administration of a new animal drug for which you have already 
received approval within that major route should be submitted as a Category II supplemental 
NADA, not a new NADA. 
                                                 
10 Typically, you should contact the reviewer assigned to the approved new animal drug and/or that reviewers Team 
Leader from the Target Animal Division in ONADE, i.e., the Division of Therapeutic Drugs for Non-Food Animals, 
Division of Production Drugs, or the Division of Therapeutic Drugs for Food Animals. 
  9  Contains Nonbinding Recommendations 
 
Appendix II is not intended to include all routes of administration for new animal drugs.  Contact 
ONADE on how to handle applications for routes of administration of new animal drugs not 
listed. 
 
D.  Adding Target Animals  Submit as a Category II Supplemental NADA 
 
The regulations regarding Category II supplemental applications provide for the addition of a 
new species (21 CFR 514.106(b)(2)(vii)), i.e., the animals for which the new animal drug is 
approved, or the target animals.  Thus, your application for approval of the use of a new 
animal drug in a new target animal should be submitted as a Category II supplemental NADA, 
not a new NADA. 
 
Sponsors should consult with ONADE as to whether it would increase administrative clarity to 
establish separate INADs for each target animal being investigated for treatment with a specific 
new animal drug.  General recommendations are as follows: 
 
  Major food animals 
 
CVM provides terms and definitions for major food-producing animals in Appendix III (a copy 
of Appendix III is also available at https://www.fda.gov/animal-veterinary/new-animal-drug-
applications/classes-major-food-producing-animals-new-animal-drug-applications, specifically 
for cattle, swine, chickens, and turkeys.  You should contact the applicable Target Animal 
Division to determine when separate INADs are appropriate for different subclasses, or subclass 
variants,11 of major food animals.  For example, if a new animal drug is being investigated for 
use only in specific subclasses or subclass variants of a major food animal, it may be appropriate 
to establish separate INADs for each subclass or subclass variant.  If the new animal drug is 
being investigated for use in all subclasses of a major food animal (e.g., beef cattle), an INAD 
established for the major food animal, but not subclass or subclass variant within the major food 
animal, may be adequate.   
 
  Companion animals 
 
Classes or breeds of companion animals generally are not distinguished in new animal drug 
indications.  Thus, unless a new animal drug is intended for use in a specific class (e.g., kitten 
versus mature cat) or breed of companion animal, separate INADs for each species (e.g., cat, 
dog, horse), but not class or breed within species, should be adequate. 
 
  Minor species 
 
In general, a separate INAD should be established for each minor species of animals being 
investigated for treatment with a specific new animal drug.  For aquaculture, it is recommended 
                                                 
11 CVM uses the term class to refer to a species of animal (e.g., cattle).  A class may have a further delineated 
subclass, a category generally defined by the physiologic status or production purpose of the animals (e.g., beef 
steers vs. beef heifers).  A subclass may be further delineated (i.e., a variant) by a production purpose or animal 
husbandry/management practice (e.g., growing beef steers in dry lot/grow yard). 
  10  Contains Nonbinding Recommendations 
that separate INADs be established for finfish, crustaceans, and mollusks.  Separate life stages, 
including eggs, may be included within a single INAD. 
 
E.  Adding or Changing Doses  Submit as a Category II Supplemental NADA 
 
As provided for in 21 CFR 514.106(b)(2)(iii), your application for approval of the use of a new 
animal drug at a dose different from your previous approval should be submitted as a Category II 
supplemental NADA, not a new NADA.  A single INAD may also be used for different doses of 
the same new animal drug product intended for use in the same target animal for the same 
indication. 
 
F.  Changing Dosing Schedule  Submit as a Category II Supplemental NADA 
 
Your application for approval of the use of a new animal drug with a dosing schedule different 
from your previous approval should be submitted as a Category II supplemental NADA, as 
provided for in 21 CFR 514.106(b)(2)(iv), not a new NADA. 
 
Examples of changing the dosing schedule include the following: 
  Original approval was for giving 2 tablets a day, 12 hours apart; change would allow 2 
tablets to be given once a day at the same time. 
  Original approval was for an injectable sustained release suspension to be given every 14 
days; change would allow injections every 10 days. 
  Original approval was for the drug to be given for a limited amount of time, such as the 
first 7 days postsurgery; change would allow the drug to be given for the life of the 
animal. 
 
Consult with ONADE as to whether it would increase administrative clarity to establish separate 
INADs for different dosing schedules of a specific new animal drug. 
 
G. Adding Indications  Submit as a Category II Supplemental NADA 
 
The Category II supplemental application regulations provide for additions of therapeutic and 
production claims (21 CFR 514.106(b)(2)(v) and (vi)).  Thus, your application for approval of 
the use of a new animal drug for additional indications should be submitted as a Category II 
supplemental NADA, not a new NADA. 
 
To increase administrative clarity for both CVM reviewers and new animal drug sponsors, 
sponsors should at least establish a separate INAD for therapeutic indications in food animals, a 
separate INAD for therapeutic indications in nonfood animals, and a separate INAD for animal 
production indications.  Contact ONADE for indications handled within the same Target Animal 
Division to determine which indications may be included in the same INAD and which should be 
in separate INADs. 
 
  11  Contains Nonbinding Recommendations 
H. Changing (Rx, OTC, VFD) Status  Submit as a Category II Supplemental 
NADA 
 
Category II supplemental applications include changes from prescription (Rx) or over-the-
counter (OTC) status (21 CFR 514.106(b)(2)(viii)).  Thus, your application for approval of such 
a change in the status of your previously approved new animal drug should be submitted as a 
Category II supplemental NADA, not a new NADA. 
 
This recommendation also applies to change in status of Veterinary Feed Directives (VFD) to 
OTC or OTC to VFD for medicated articles/feeds. 
 
I.  Replacing, Adding, Deleting, or Changing Concentrations of Inactive 
Ingredients 
 
Replacing, adding, deleting, or changing the concentration of inactive ingredients from that 
found in an approved new animal drug may result in a new animal drug composition that is not 
generally recognized as safe and effective.  Such a change may be considered a new animal drug 
(21 U.S.C.  321(v); 21 CFR 510.3(g)(1)).  However, the Category II supplemental application 
regulations also provide for changes in composition of the final product and changes in 
quality, purity, strength, and identity specifications of the active or inactive ingredients (21 
CFR 514.106(b)(2)(i) and (ii)).  Furthermore, these regulations provide for changes in active 
ingredient concentration (21 CFR 514.106(b)(2)(i)), which will usually occur with a concurrent 
change in the concentration of inactive ingredients (see section IV.J. Changing Concentrations of 
Active Ingredients).  Therefore, as discussed below, the nature of the changes to the inactive 
ingredient composition of a new animal drug product will determine whether it is submitted as a 
new NADA or a Category II supplemental application. 
 
CVM recognizes that many changes to the inactive ingredient composition of a new animal drug 
product do not significantly affect the safety and effectiveness of the API.  In such situations, a 
new NADA would not be warranted.  For example, the deletion or reduction of an ingredient 
intended to affect only the color of a product can be reported in an annual report (21 CFR 
514.8(b)(4)(ii)(B)).12  In some situations, additional safety and/or effectiveness data may need to 
be submitted to CVM for a new formulation.  For these types of changes to the inactive 
ingredient composition that require review of safety and/or effectiveness data due to such 
changes in drug delivery and/or distribution of the API, an application should be submitted as a 
Category II supplemental NADA. 
 
However, some changes in inactive ingredient composition of a previously approved new animal 
drug may significantly affect the safety and/or effectiveness of the formulation compared to the 
previously approved formulation.  In such situations, your application for an API formulation in 
which inactive ingredients have been replaced, added, deleted, or their concentration changed 
from the new animal drug for which they have already received approval should be submitted as 
a new NADA, not a Category II supplemental NADA. 
                                                 
12 Additionally, changes consistent with GFI #83 may be submitted as Category I or Category II supplemental 
NADAs. 
  12  Contains Nonbinding Recommendations 
 
Because of the potential difficulty in determining the significance of replacing, adding, deleting, 
or changing the concentration of inactive ingredients of your previously approved new animal 
drug, consult with ONADE to determine whether the application should be submitted as a new 
NADA, a Category II supplemental NADA, or another appropriate administrative vehicle.13  The 
reason for the proposed change may be considered during the review process.  It may be 
necessary for CVM to review safety and effectiveness information relevant to the proposed  
change during the investigational (INAD) process to determine whether the application should be 
a new NADA, Category II supplemental NADA, or another appropriate administrative vehicle 
(see e.g., 21 CFR 514.8). 
 
Consult with ONADE to determine whether separate INADs should be established for APIs with 
different inactive ingredient compositions.  During the early stages of development of a new 
animal drug formulation, it may be acceptable to use one INAD until a specific formulation is 
selected for further investigation. 
 
J.  Changing Concentrations of Active Ingredients 
 
The Category II supplemental application regulations provide for changes in active ingredient 
concentration in addition to changes in the composition of the final product (21 CFR 
514.106(b)(2)(i)).  A change in the concentration of an active ingredient is necessarily 
accompanied by a change in the concentration of one or more inactive ingredients, and/or by a 
change to the ratio of active ingredients if two or more active ingredients are used in the 
formulation.  These secondary changes may or may not significantly affect the function of the 
API or the safety and/or effectiveness of the new formulation compared to the previously-
approved formulation.  Therefore, the nature and degree to which the proposed changes to the 
inactive ingredients affect the function of the API(s) or safety of the new formulation should be 
used to determine whether an application to change the active ingredient concentration should be 
submitted as a new NADA or a Category II supplemental NADA.  Refer to section IV.I. 
Replacing, Adding, Deleting, or Changing Concentrations of Inactive Ingredients for guidance. 
 
Sponsors should consult with ONADE to determine whether separate INADs should be 
established for new animal drug formulations with different concentrations of active ingredients. 
 
K. Multiple Changes 
 
You can request multiple concurrent changes to an approved new animal drug.  For changes that 
require FDA to reevaluate safety and/or effectiveness data, ONADE will consider whether the 
requested changes are related to each other and, therefore, should be submitted in a single 
application (new NADA or Category II supplemental NADA).  If the concurrent requested 
changes are not related to each other and could be filed individually as stand-alone submissions, 
they should be submitted as separate applications (new NADA(s) and/or Category II 
supplemental NADA(s)).  The decision as to whether an application should be submitted as a 
                                                 
13 For example, as a category I supplemental NADA or in an annual report. 
  13  Contains Nonbinding Recommendations 
new NADA or Category II supplemental NADA should be based on how the specific changes 
within the application are usually handled if submitted individually. 
 
In deciding whether multiple requested changes to an approved new animal drug should be 
submitted in a single or multiple application(s), ONADE will consider the relationship between 
the proposed changes, e.g., whether one change is necessary to allow the other change.  If the 
proposed changes are unrelated (i.e., one change is not necessary to allow approval of the other 
change), separate safety and/or effectiveness data sets typically will be needed for each change, 
and each change should usually be submitted in separate applications.  For example: 
 
Example 1.  In this example, assume a sponsor requests to expand usage of their 
approved new animal drug in an additional target animal for the same indication, and the 
safe and effective dose for the additional target animal is different from the dose 
originally approved for the first target animal.  In this case, the request is for two 
concurrent changes from the original approval:  a new target animal and a new dose for 
that target animal.  These requests are related and cannot stand alone because a new dose 
is necessary to gain approval in the new target animal, and the same safety and 
effectiveness data set will support the two concurrent changes.  Thus, the request for 
these two related changes from the original approval (target animal and dose for that 
target animal) should be submitted in the same application. 
 
Example 2.  In this example, assume a sponsor requests approval of a new dosage form 
of their approved new animal drug and that the new dosage form has different inactive 
ingredients and is safe and effective at a different dose of the API than the approved 
dosage form.  In this case, the request is for three changes from the original approval:  a 
new dosage form, changes in inactive ingredients, and a new dose.  These requests are 
related and cannot stand alone because a new dose and different inactive ingredients are 
necessary to gain approval of the new dosage form, and the same safety and effectiveness 
data set will support the three concurrent changes.  Thus, the sponsors request for these 
three related changes from the original approval (dosage form, inactive ingredients, and 
dose) should be submitted in the same application. 
 
Example 3.  In this example, assume a sponsor wishes to expand the approved dose 
range for an already approved product (original dosage form) as well as gain approval of 
a new dosage form of the API (with changes in inactive ingredients and dose necessary to 
allow approval of the new dosage form).  In this scenario, the request for the change in 
dose range for the original dosage form is unrelated to, and can stand alone from, the 
request for a new dosage form (and associated changes in inactive ingredients and dose).  
Separate safety and/or effectiveness data sets would be necessary to gain approval of the 
expanded dose range for the original dosage form versus the new dosage form.  Thus, the 
request for the expanded dose range for the original dosage form should be submitted in a 
separate application from the request for approval of the new dosage form (and 
associated changes in inactive ingredients and dose). 
 
Example 4.  In this example, assume a sponsor has an approved new animal drug to treat 
a specific disease in dogs.  The sponsor wishes to expand the approved dose range for 
  14  Contains Nonbinding Recommendations 
dogs, as well as gain approval of use of the drug to treat the same disease in cats.  The 
requested change in the dog approval is unrelated to, and can stand alone from, the 
request for the cat approval.  Separate safety and effectiveness data sets would be 
necessary to gain approval of the expanded dose range for dogs versus gaining approval 
for use in cats.  Thus, the request for expanding the approved dose range for dogs should 
be submitted in a separate application from the request for approval in cats. 
 
Example 5.  In this example, assume a sponsor who has an approved new animal drug 
for increased rate of weight gain in growing beef steers and heifers on pasture (stocker, 
feeder, and slaughter) wishes to add an indication of increased carcass leanness in 
growing beef steers and heifers on pasture (stocker, feeder, and slaughter) plus gain 
approval of the increased rate of weight gain and carcass leanness indications in growing 
beef steers and heifers fed in confinement for slaughter.  The requested change for 
growing beef steers and heifers on pasture (stocker, feeder, and slaughter) is unrelated to, 
and can stand alone from, the request for approval in growing beef steers and heifers fed 
in confinement for slaughter.  The requested new indication for growing beef steers and 
heifers on pasture (stocker, feeder, and slaughter) would require separate safety and/or 
effectiveness data from the request for growing beef steers and heifers fed in confinement 
for slaughter.  Thus, the request for adding the carcass leanness indication for growing 
beef steers and heifers on pasture (stocker, feeder, and slaughter) should be submitted in a 
separate application from the request for approval of the increased rate of weight gain and 
carcass leanness indications in growing beef steers and heifers fed in confinement. 
 
Once a determination is made as to whether multiple proposed changes may be submitted as one 
or separate applications, contact ONADE if you need help deciding whether each application 
should be submitted as a new NADA or a Category II supplemental NADA.  In general, if any 
one of the changes proposed within an application could, on its own, be submitted as a new 
NADA, the application should be submitted as a new NADA, not a supplemental NADA.  In 
summary, using the previous examples: 
 
Example 1.  A request to approve a new animal drug for use in an additional target 
animal at a different dose than for the original approval should be submitted as a single 
Category II supplemental NADA. 
 
Example 2.  A request to approve a new dosage form of a new animal drug with 
necessary changes in inactive ingredients and dose from the approved dosage form 
should be submitted as a single new NADA. 
 
Example 3.  A request for additional doses of an approved dosage form should be 
submitted as a Category II supplement to the original NADA, whereas the request for the 
new dosage form should be submitted as a new NADA. 
 
Example 4.  The request to expand the approved dose range for an approved new animal 
drug in dogs should be submitted as a Category II supplement to the original NADA; the 
request to gain approval of use of the drug to treat the same disease in cats should be 
submitted as a separate Category II supplemental NADA. 
  15  Contains Nonbinding Recommendations 
 
Example 5.  The request to add a production indication in growing beef steers and heifers 
on pasture (stocker, feeder, and slaughter) should be submitted as a Category II 
supplement to the original NADA; the request for production indications in growing beef 
steers and heifers fed in confinement for slaughter should be submitted as a separate 
Category II supplemental NADA. 
 
An exception may apply for multiple requested changes such as described in Examples 4 and 5 
where: 
1)  Essentially the same product applies to each request (i.e., same API, dosage form, and 
route of administration, and no differences in inactive ingredient composition that 
significantly alter the safety and effectiveness of the new animal drug); 
2)  All safety, effectiveness, and chemistry, manufacturing and control information for each 
request has been reviewed under one or more INADs; 
3)  Technical section complete letters have been issued by ONADE for each of these 
technical sections for each request under one or more INADs; 
4)  All requests would be reviewed by the same Target Animal Division in ONADE; and 
5)  You plan to submit an administrative NADA (or administrative Category II supplemental 
NADA, if appropriate).14 
 
If these criteria are met, you may be able to submit multiple requests as one administrative 
NADA or one administrative Category II supplemental NADA.  Consult with ONADE if you 
believe your requests meet these criteria and you wish to submit your requests as one 
administrative NADA or one administrative Category II supplemental NADA. 
 
You should also consult with ONADE as to whether it would increase administrative clarity to 
establish one or more separate INAD(s) for investigation of multiple proposed changes to an 
approved new animal drug.  In general, changes that should be submitted as a new NADA should 
be investigated under a separate INAD. 
 
V.  Conclusions 
 
By applying the recommendations in this guidance, we believe that applications for changes to 
approved new animal drugs will be handled in a more consistent manner.  This in turn will 
improve the clarity of the administrative record for new animal drug applications.  You are 
encouraged to contact ONADE with any further questions regarding the most appropriate 
administrative vehicle for proposed changes to approved new animal drugs. 
                                                 
14 See CVM GFI #132, Administrative Applications and the Phased Review Process 
(https://www.fda.gov/media/70029/download). 
  16  Contains Nonbinding Recommendations 
 
Appendix I.  Examples of Dosage Forms of New Animal Drugs 
 
DOSAGE FORM 1  VARIATIONS 2   DEFINITION 
Block  none  A solid dosage form usually in the shape of a square 
or rectangle that animals consume voluntarily; but not 
a Type C Medicated Feed. 
Capsule  Capsule  A dosage form in which the drug is enclosed within 
either a hard or soft soluble container or shell made 
from a suitable form of gelatin. 
Capsule  Capsule, Coated  A capsule with an additional designated coating. 
Cream  none  A semisolid dosage form where the drug is dissolved 
or dispersed in a base, usually consisting of 
emulsions of oil and water, where water is the main 
ingredient. 
Culture  none  Microorganisms or living tissue cells in special media 
conducive to their growth. 
Emulsion  none  A liquid dosage form with a two-phase system in 
which one liquid is dispersed throughout another 
liquid in the form of small droplets. 
Gel  none  A semisolid dosage form consisting of either 
suspensions made up of small inorganic particles or 
large organic molecules interpenetrated by a liquid; 
usually water-based and thickened without oil or fat. 
Liquid  none  A liquid dosage form consisting of a pure neat 
chemical in its liquid state (an intermediate state 
entered as matter goes from solid to gas).  Do not use 
this term to describe solutions. 
Ointment  none  A semisolid dosage form, usually consisting of 
emulsions of oil and water, where oil is the main 
ingredient; intended for topical application. 
Packing  none  A solid dosage form consisting of a material, covered 
by or impregnated with a drug, that is inserted into a 
body cavity or between the tooth enamel and the 
gingival margin. 
Particulates  Crumbles  A solid dosage form consisting of small irregularly 
shaped fragments or particles; but not a Type C 
Medicated Feed. 
Particulates  Granule  A solid dosage form consisting of particles or grains 
smaller and more uniform than crumbles; but not a 
Type C Medicated Feed. 
  17  Contains Nonbinding Recommendations 
DOSAGE FORM 1  VARIATIONS 2   DEFINITION 
Paste  none  A semisolid dosage form that is a fatty, viscous, or 
mucilaginous base, or a mixture of starch and 
petrolatum. 
Pellet  none  A solid dosage form in a small mass consisting of 
highly purified drug with or without excipients, made 
by compression, molding, and/or extrusion; but not a 
Type C Medicated Feed. 
Powder   none  A solid dosage form consisting of an intimate mixture 
of dry, finely divided drugs and/or chemicals. 
Powder, Aerosol   none  A powder product packaged under pressure and 
released upon activation of an appropriate valve 
system. 
Solid Matrix  none  A solid dosage form in a special shape (e.g., ring, 
cylinder, cartridge, etc.) and embedded with the drug.  
It is typically placed in a body cavity or under the skin, 
where the medication is released for localized or 
systemic effects. 
Solution  Solution  A liquid dosage form in which the drug is dissolved in 
a solvent or mixture of mutually miscible solvents; but 
not a Type C Medicated Feed. 
Solution  Solution, Concentrate  A solution in which the concentration of drug is 
increased by the evaporation of nonactive ingredients.  
The concentrated solution is diluted with appropriate 
vehicles before the drug is administered. 
Solution  Powder, for Solution  A powder product, which upon the addition of suitable 
vehicles, yields a solution. 
Sponge  none  A solid dosage form in which the drug is embedded in 
an absorbent pad of natural or synthetic materials. 
Spray   none  A liquid dosage form in which the drug is minutely 
dispersed by a jet of air or steam. 
Spray, Aerosol  none  A spray which utilizes a compressed gas as the 
propellant to provide the force necessary to expel the 
product as a wet spray. 
Suspension   Suspension  A liquid dosage form that consists of solid particles 
dispersed throughout a liquid phase, in which the 
particles are not soluble. 
Suspension   Suspension,  A suspension in which the concentration of drug is 
Concentrate  increased by the evaporation of nonactive ingredients.  
The concentrated suspension is diluted with 
appropriate vehicles before the drug is administered. 
  18  Contains Nonbinding Recommendations 
DOSAGE FORM 1  VARIATIONS 2   DEFINITION 
Suspension   Powder, for  A powder product, which upon the addition of suitable 
Suspension  vehicles, yields a suspension. 
Suspension,  none  A suspension formulated to allow a reduction in 
Extended Release  dosing frequency. 
Syrup  none  A liquid dosage form consisting of a solution with high 
concentrations of sucrose or other sugars. 
Tablet, Compressed  Tablet  A solid dosage form containing a mixture of the drug 
and diluents that are granulated and compressed. 
Tablet, Compressed  Bolus  A large tablet.   
Tablet, Compressed  Tablet, Coated  A tablet that is covered with a designated coating. 
Tablet, Compressed  Tablet, Flavored  A tablet that contains compounds intended to improve 
palatability. 
Tablet, Extruded   none  A tablet that is formulated by extrusion and typically is 
intended to be chewable. 
Tablet, Effervescent   none  A tablet that contains mixtures of acids (e.g., citric 
acid, tartaric acid) and sodium bicarbonate, which 
release carbon dioxide when dissolved in water; it is 
intended to be dissolved or dispersed in water before 
administration. 
Tablet, Sustained  Tablet, Sustained  A tablet formulated to allow continued release of the 
Release  Release  drug over time. 
Tablet, Sustained  Bolus, Sustained  A bolus formulated to allow continued release of the 
Release  Release  drug over time. 
Medicated  Type A Medicated  Intended solely for use in the manufacture of another 
Article/Feed 3  Article  Type A Medicated Article or a Type B or Type C 
Medicated Feed.  It consists of a new animal drug(s), 
with or without carrier (e.g., calcium carbonate, rice 
hull, corn, gluten) with or without inactive ingredients, 
as defined in 21 CFR 558.3(b)(2). 
Medicated   Type B Medicated  Intended solely for the manufacture of other 
Feed  Medicated Feeds (Type B or Type C).  It contains a 
Article/Feed 3 
substantial quantity of nutrients including vitamins 
and/or minerals and/or other nutritional ingredients in 
an amount not less than 25 percent of the weight.  It is 
manufactured by diluting a Type A Medicated Article 
or another Type B Medicated Feed, and meets the 
additional requirements defined in 21 CFR 
558.3(b)(3). 
  19  Contains Nonbinding Recommendations 
DOSAGE FORM 1  VARIATIONS 2   DEFINITION 
Medicated   Type C Medicated  Intended as the complete feed for the animal or may 
Feed  be fed top dressed (added on top of usual ration) on 
Article/Feed 3 
or offered free-choice (e.g., supplement) in 
conjunction with other animal feed.  It contains a 
substantial quantity of nutrients including vitamins, 
minerals, and/or other nutritional ingredients.  It is 
manufactured by diluting a Type A Medicated Article 
or a Type B Medicated Feed.  A Type C Medicated 
Feed may be further diluted to produce another Type 
C Medicated Feed, as defined in 21 CFR 558.3(b)(4).  
A dosage form that meets this definition may be 
considered a Type C Medicated Feed even if it is 
provided in the physical form of blocks, crumbles, 
granules, pellets, or other dosage forms described 
above. 
1 
When changing from one dosage form to another in this column, the application should be submitted as 
a new NADA. 
2 When changing from one variation to another within the same dosage form of an approved new animal 
drug, the application should generally be submitted as a Category II supplemental NADA. 
3 See section IV.B. New Dosage Form  Submit as New NADA regarding Medicated Articles/Feeds. 
  20  Contains Nonbinding Recommendations 
Appendix II.  Examples of Routes of Administration for New Animal Drugs 
 
MAJOR  DESCRIPTION  VARIATIONS 2  CFR 
ROUTE 1  REFERENCE 
 
Oral  Through the mouth.    Oral:  into the mouth or pharynx  21 CFR 558 
and swallowed.  (Animal 
Feeds); 21 
In Feed:  by application in, on, or 
CFR 520 
with feed. 
(Oral) 
In Drinking Water:  by dissolving 
 
or diluting in drinking water. 
By Intubation: by tube inserted 
through the mouth or nose into the 
gastrointestinal tract. 
Injection  Placing a non-formed (liquid or  Intramuscular:  in a muscle.  21 CFR 522 
semisolid) drug product into a 
Intravenous:  in a vein.   
tissue or body cavity through a 
Subcutaneous:  directly under the 
needle. 
skin. 
Intraarterial:  in an artery. 
Intraarticular:  in a joint. 
Intraperitoneal:  in the peritoneal 
cavity. 
Intradermal:  in the dermis of the 
skin. 
Intraruminal:  in the rumen. 
Subconjunctival:  under the 
conjunctiva. 
Implantation  Placing a formed (solid) drug  none  21 CFR 522 
product into a tissue or body 
cavity. 
Topical  Directly to a particular area of  none  21 CFR 524 
the external body surface; 
affects only the area to which it 
is applied (in contrast to 
transdermal); includes otic 
administration. 
Transdermal   On or into the skin resulting in a  none  21 CFR 524 
systemic action (in contrast to 
topical). 
Transmucosal,  Across the oral mucous  none  21 CFR 529 
Oral  membrane resulting in systemic 
action. 
  21  Contains Nonbinding Recommendations 
MAJOR  DESCRIPTION  VARIATIONS 2  CFR 
ROUTE 1  REFERENCE 
 
Intramammary  Into the mammary gland,  none  21 CFR 526 
including mammary infusion 
into a quarter through the teat 
canal. 
Nasal  Into or through the nose,  none  21 CFR 529 
localized to the nasal 
passages. 
Inhalant  Through the respiratory  none  21 CFR 529 
system. 
Ophthalmic  To the eye.  none  21 CFR 524 
Rectal  Into the rectum.  none  21 CFR 529  
Intravaginal  Into the vagina.  none  21 CFR 529 
Intrauterine  Into the uterus.  none  21 CFR 529 
Aquatic  Immersion therapy  External-Systemic:  absorbed  21 CFR 529 
Exposure  administered to aquatic animals  through the skin, gills, etc., and 
via bath treatment (exposure).  intended action is systemic. 
External-Topical:  direct contact 
with the external surfaces of skin, 
gills, etc., and intended action is 
local. 
In ovo  Into a fertilized egg (poultry)  none  none 
after laid by the female. 
Egg Dip  Submerged and/or coated with  none  21 CFR 529 
the drug. 
1 When changing from one major route of administration to another in this column, the application should 
be submitted as a new NADA. 
2 When changing from one variation to another within the same major route of administration of an 
approved new animal drug, the application should generally be submitted as a Category II supplemental 
NADA. 
 
  22  Contains Nonbinding Recommendations 
Appendix III.  Target Animal Classes of Major Food Animals 
 
CVM has posted these tables on our website for easy access by users 
(https://www.fda.gov/animal-veterinary/new-animal-drug-applications/classes-major-food-
producing-animals-new-animal-drug-applications). 
 
Please note that the labeling for some approved animal drugs includes legacy terms that have 
been used since before FDA established the terminology in these tables; therefore, the tables 
do not encompass all terminology for all classes of major food-producing animals. 
 
Cattle 
 
Cattle are defined as animals of the Bos genus, either Bos taurus taurus or Bos taurus indicus.  
There are three major subclasses of cattle: veal calves, beef cattle, and dairy cattle. 
 
Veal Calves 
 
Veal calves are typically dairy breeds of immature male or female cattle that are raised to 
produce meat (veal) for human consumption. Most are pre-ruminating; but, depending on 
management, age, and diet, they may be ruminating. 
 
The following subclass of veal calves may be used to further define this major subclass: 
 
Subclass  Definition 
Bob Veal  Veal calves less than 2 weeks of age and pre-ruminating. 
 
Beef Cattle 
 
Beef cattle are defined as cattle that are raised primarily to produce meat (either beef or dairy 
breeds) for human consumption or to produce offspring (beef breeds) that will produce meat 
intended for human consumption.   
 
The following subclasses of beef cattle may be used to further define this major subclass: 
 
A.  Beef Calves 
 
Beef cattle (beef breeds only) nursing their dams from birth until weaning. May be 
pre-ruminating or ruminating. Formerly referred to as suckling beef calves. Excludes 
veal calves. 
 
The following variants of beef calves may be used to further define this subclass: 
 
Variant  Definition 
Beef Calves less than  Beef calves considered pre-ruminating and nursing their dams 
2 months of age  from birth until 2 months of age. 
  23  Contains Nonbinding Recommendations 
Variant  Definition 
Beef Calves 2 months  Beef calves considered ruminating and nursing their dams from 2 
of age and older  months of age to weaning.  
 
B.  Beef Steers 
 
Weaned castrated male cattle (beef and dairy breeds) intended for slaughter, housed 
in any setting and receiving their diet from any source(s). 
 
The following variants and subsets of variants of beef steers may be used to further 
define this subclass: 
 
Variant  Subset  Definition 
Weaned growing beef steers (beef and dairy breeds) 
maintained on pasture and receiving the majority of their diet 
from grazing. Refers to cattle considered to be stocker, feeder, 
and slaughter cattle, and these words are always included in 
the parenthetical portion of the class name.  
Growing 
Stocker refers to weaned growing cattle grazing pasture prior 
Beef Steers 
on Pasture  No  to finishing and slaughter; they are usually younger, weigh less, 
(stocker,  subsets  and are of lower condition (finish) than feeder cattle. 
feeder, and  Feeder refers to weaned growing cattle grazing pasture and of 
slaughter)  sufficient weight and maturity to be placed on high-energy 
rations for finishing; they are generally older, weigh more, and 
carry more condition (finish) than stocker cattle.  
Slaughter refers to weaned growing cattle grazing pasture and 
suitable for slaughter. 
Growing  Weaned growing beef steers (beef and dairy breeds) 
No 
Beef Steers  maintained in a dry lot. They receive the majority of their diet 
subsets 
in a Dry Lot  from harvested forage (possibly with a supplement). 
Weaned growing and finishing beef steers (beef and dairy 
Growing 
breeds) intended only for slaughter and confined in group pens 
Beef Steers  Includes 
and fed a progressively high-energy diet ad libitum as their sole 
Fed in  all 
ration until slaughter. May also be referred to as feed yard or 
Confinement  subsets 
feedlot cattle in the industry. Includes growing beef steers in a 
for Slaughter 
grow yard (see definition below).  
Growing  A subset population of growing beef steers fed in confinement 
Growing Beef  Beef  for slaughter, these are weaned growing beef steers (beef and 
Steers Fed in  Steers  dairy breeds) confined in group pens and fed a moderate- to 
Confinement  in a  high-roughage diet ad libitum as their sole ration prior to the 
for Slaughter  Grow  finishing stage. Grow yards may also be referred to as starter 
Yard  yards or backgrounding yards in the industry. 
 
 
 
  24  Contains Nonbinding Recommendations 
C.  Beef Heifers 
 
Weaned female beef cattle intended for breeding (beef breeds) or slaughter (beef and 
dairy breeds) that have not yet calved, housed in any setting and receiving their diet 
from any source(s). 
 
The following variants and subsets of variants of beef heifers may be used to further 
define this subclass: 
 
Variant  Subset  Definition 
Weaned female beef heifers (beef breeds only) that are 
intended only for breeding to produce calves for meat 
Replacement  Includes all  production. 
Beef Heifers  subsets 
If reproductive safety is not evaluated, an age restriction 
of less than 1 year will apply. 
Weaned replacement beef heifers maintained on pasture 
Replacement  Replacement  and receiving the majority of their diet from grazing. 
Beef Heifers 
Beef Heifers 
If reproductive safety is not evaluated, an age restriction 
on Pasture 
of less than 1 year will apply. 
Weaned growing beef heifers (beef and dairy breeds) 
intended only for slaughter (i.e., not for reproductive 
purposes) maintained on pasture and receiving the 
majority of their diet from grazing. Refers to cattle 
considered to be stocker, feeder, and slaughter cattle, 
and these words are always included in the parenthetical 
portion of the class name.  
Growing 
Stocker refers to weaned growing cattle grazing pasture 
Beef Heifers 
prior to finishing and slaughter; they are usually younger, 
on Pasture 
No subsets  weigh less, and are of lower condition (finish) than 
(stocker, 
feeder cattle. 
feeder, and 
slaughter)  Feeder refers to weaned growing cattle grazing pasture 
and of sufficient weight and maturity to be placed on high-
energy rations for finishing; they are generally older, 
weigh more, and carry more condition (finish) than 
stocker cattle.  
Slaughter refers to weaned growing cattle grazing 
pasture and suitable for slaughter. 
Growing  Weaned growing beef heifers (beef and dairy breeds) 
Beef Heifers  No subsets  maintained in a dry lot. They receive the majority of their 
in a Dry Lot  diet from harvested forage (possibly with a supplement).  
  25  Contains Nonbinding Recommendations 
Variant  Subset  Definition 
Weaned growing and finishing beef heifers (beef and 
Growing  dairy breeds) intended only for slaughter (i.e., not for 
Beef Heifers  reproductive purposes) and confined in group pens and 
Includes all 
Fed in  fed a progressively high-energy diet ad libitum as their 
subsets 
Confinement  sole ration until slaughter. May also be referred to as feed 
for Slaughter  yard or feedlot cattle in the industry. Includes growing 
beef heifers in a grow yard (see definition below). 
A subset population of growing beef heifers fed in 
confinement for slaughter, these are weaned growing 
Growing Beef 
Growing Beef  beef heifers (beef and dairy breeds) confined in group 
Heifers Fed in 
Heifers in a  pens and fed a moderate- to high-roughage diet ad 
Confinement 
Grow Yard  libitum as their sole ration prior to the finishing stage. 
for Slaughter 
Grow yards may also be referred to as starter yards or 
backgrounding yards in the industry. 
 
D.  Beef Bulls 
 
Weaned intact male beef cattle intended for breeding (beef breeds) or slaughter (beef 
and dairy breeds), housed in any setting and receiving their diet from any source(s). 
 
The following variants of beef bulls may be used to further define this subclass: 
 
Variant  Definition 
Weaned intact male beef bulls (beef breeds only) intended only for 
breeding.  
Beef Bulls Intended 
for Breeding  If reproductive safety is not evaluated, an age restriction of less 
than one year will apply. 
Beef Bulls Intended  Weaned intact male beef cattle intended only for slaughter (beef 
for Slaughter  and dairy breeds). 
 
E.  Beef Cows 
 
Beef breed female cattle that have calved. 
 
Dairy Cattle 
 
Dairy cattle are defined as cattle that are raised primarily to produce milk for human 
consumption and/or to produce offspring that will produce milk or meat (including veal) for 
human consumption. 
 
The following subclasses of dairy cattle may be used to further define this major subclass: 
 
 
 
 
  26  Contains Nonbinding Recommendations 
A.  Dairy Calves 
 
Pre-ruminating dairy cattle from birth until weaning being fed a ration that includes 
milk or liquid milk replacer. Excludes veal calves. 
 
B.  Replacement Dairy Heifers 
 
Weaned female dairy cattle that have not yet calved and are intended only for 
breeding and future milk production, housed in any setting and receiving their diet 
from any source(s). If reproductive safety is not evaluated, an age restriction of less 
than 1 year will apply. 
 
The following variants of replacement dairy heifers may be used to further define this 
subclass: 
 
Variant  Definition 
Periparturient 
Replacement dairy heifers approximately 3 weeks before calving. After 
Replacement 
calving they become periparturient dairy cows. 
Dairy Heifers 
Replacement 
Weaned replacement dairy heifers maintained on pasture and receiving 
Dairy Heifers on 
the majority of their diet from grazing. 
Pasture 
 
C.  Dairy Bulls 
 
Weaned intact male dairy cattle intended for breeding. If reproductive safety is not 
evaluated, an age restriction of less than 1 year will apply. 
 
D.  Dairy Cows 
 
Female dairy cattle that have calved. 
 
The following variants of dairy cows may be used to further define this subclass: 
 
Variant  Definition 
Lactating Dairy 
Dairy cows that are producing milk for human food. 
Cows 
Dairy cows that have previously lactated, but which are not currently 
Dry Dairy Cows 
producing milk for human food (i.e., dairy cows between two lactations). 
Dairy cows that have previously lactated, and are in the transition period 
Periparturient 
from approximately 3 weeks before to approximately 3 weeks after 
Dairy Cows 
calving. 
 
 
 
  27  Contains Nonbinding Recommendations 
Swine 
 
Swine are defined as animals of the Sus genus, either Sus scrofa domesticus or Sus 
domesticus, that are raised primarily to produce meat for human consumption or to produce 
offspring that will produce meat for human consumption. 
 
The following subclasses of swine may be used to further define this class: 
 
A.  Nursing Piglets 
 
Swine from birth until weaning. May be referred to as weanling pigs, baby pigs, or 
suckling piglets in the industry. 
 
B.  Nursery Swine 
 
Swine intended for slaughter, from weaning to end of nursery phase at approximately 
40 to 70 lbs (18 to 32 kg). May be referred to as starter pigs in the industry. 
 
C.  Growing Swine 
 
Swine intended for slaughter, from approximately 40 to 70 lbs (18 to 32 kg) to 120 to 
150 lbs (55 to 68 kg). 
 
D.  Finishing Swine 
 
Swine intended for slaughter, from approximately 120 to 150 lbs (55 to 68 kg) to 
market weight. 
 
E.  Boars 
 
Intact male swine intended for breeding or slaughter. 
 
The following variants of boars may be used to further define this subclass: 
 
Variant  Definition 
Boars Intended for 
Boars intended for breeding. 
Breeding 
Boars intended for slaughter, including chemically castrated males 
Boars Intended for 
and those removed from breeding service. May also be referred to 
Slaughter 
as culled boars in the industry. 
 
F.  Barrows 
 
Surgically castrated male swine intended for slaughter. 
 
G.  Gilts 
 
Female swine intended for breeding or slaughter that have never farrowed a litter. 
  28  Contains Nonbinding Recommendations 
 
The following variants of gilts may be used to further define this subclass: 
 
Variant  Definition 
Replacement Gilts  Gilts intended for breeding. 
Gestating Replacement Gilts  Replacement gilts that are pregnant. 
Gilts Intended for Slaughter  Gilts intended for slaughter. 
 
H.  Sows 
 
Female swine that have farrowed. 
 
The following variants of sows may be used to further define this subclass: 
 
Variant  Definition 
Gestating Sows  Sows that are pregnant. 
Lactating Sows  Sows that are producing milk. 
Weaned Sows  Sows that have farrowed and completed nursing a litter. 
Sows Intended for  Sows that have been removed from breeding service. May also be 
Slaughter  referred to as culled sows in the industry. 
 
 
Chickens 
 
Chickens are defined as animals of the subspecies Gallus gallus domesticus that are raised 
primarily to produce meat and/or eggs for human consumption or to produce offspring that will 
produce meat and/or eggs for human consumption.  
 
The following subclasses of chickens may be used to further define this class: 
 
A.  Embryonated Chicken Eggs 
 
Eggs containing a chicken embryo at any stage of embryonic development. 
 
B.  Chicks 
 
Chickens from hatch until they are able to survive in ambient temperature (no longer 
brooded). This is the initial post-hatch phase of the subclasses identified in the 
remainder of this table. 
 
  29  Contains Nonbinding Recommendations 
When used on approved labeling, the term chicks only refers to chicks of the 
chicken species. If a drug product is approved for use in chicks of another species, 
the labeling should clearly state (species) chicks (e.g., quail chicks). 
 
C.  Broiler Chickens 
 
Chickens raised from hatch, grown to a marketable weight, and intended for meat 
production. Includes Rock Cornish game hen or Cornish game hen, broiler or fryer, 
roaster or roasting chicken, and capon. 
 
D.  Replacement Chickens 
 
Chickens raised from hatch to sexual maturity and intended to become laying hens or 
breeder chickens. 
 
The following variants of replacement chickens may be used to further define this 
subclass: 
 
Variant  Definition 
Breeder 
Replacement  Male and female chickens intended to become breeder chickens. 
Chickens 
Laying Hen 
Replacement  Female chickens intended to become laying hens. 
Chickens 
 
E.  Laying Hens 
 
Mature female chickens that produce non-fertilized eggs for consumption. 
 
F.  Breeder Chickens 
 
Sexually mature male and female chickens intended to produce fertilized eggs for 
hatching. 
 
The following variants of breeder chickens may be used to further define this 
subclass: 
 
Variant  Definition 
Broiler Breeder  Chickens intended to produce fertilized eggs for hatching into broiler 
Chickens  chickens or broiler breeder replacement chickens. 
Layer Breeder  Chickens intended to produce fertilized eggs for hatching into laying 
Chickens  hen replacement chickens or layer breeder replacement chickens. 
 
 
  30  Contains Nonbinding Recommendations 
Turkeys 
 
Turkeys are defined as animals of the species Meleagris gallopavo that are commonly raised 
primarily to produce meat for human consumption or to produce offspring that will produce meat 
for human consumption.  
 
The following subclasses of turkeys may be used to further define this class: 
 
A.  Embryonated Turkey Eggs 
 
Eggs containing a turkey embryo at any stage of embryonic development. 
 
B.  Turkey Poults 
 
Turkeys from hatch until they are able to survive in ambient temperature (no longer 
brooded). This is the initial post-hatch phase of the subclasses identified in the 
remainder of this table. 
 
C.  Growing Turkeys 
 
Turkeys raised from hatch and growing to a marketable weight and intended for meat 
production. Includes fryer-roaster, young turkey, and yearling turkey. 
 
D.  Breeder Replacement Turkeys 
 
Turkeys raised from hatch to sexual maturity and intended to become breeder 
turkeys. 
 
E.  Breeder Turkeys 
 
Sexually mature male and female turkeys intended to produce fertilized eggs for 
hatching into growing turkeys or breeder replacement turkeys. 
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