Exhibit 10.87.1
 
GUARANTY AGREEMENT
 
dated as of August 31, 2002
 
Between
 
DREW SCIENTIFIC GROUP PLC
 
and
 
SYNBIOTICS CORPORATION

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GUARANTY AGREEMENT
 
Dated as of August 31, 2002
 
In consideration of the execution and delivery by Synbiotics Corporation of the
Asset Purchase Agreement of even date herewith, DREW SCIENTIFIC GROUP PLC, a
corporation organized under the laws of England and Wales, hereby agrees with
SYNBIOTICS CORPORATION as follows (with certain terms used herein being defined
in Article 5):
 
ARTICLE 1
 
GUARANTY
 
SECTION 1.1  Guaranty of Payment and Performance.    The Guarantor hereby (a)
guarantees to the Guaranteed Party the due and punctual payment, observance and
performance of all of the Guaranteed Obligations in accordance with their
respective terms and when and as due (whether at maturity, by reason of
acceleration or otherwise), or deemed to be due pursuant to Section 1.2, and (b)
agrees so to pay, observe or perform the same when so due, or deemed to be due,
upon demand.
 
SECTION 1.2  Continuance and Acceleration of Guaranteed Obligations upon Certain
Events.    If:
 
(a)  the maker of the Promissory Note fails to timely pay any payment when due;
 
(b)  any event with respect to which any provision of the Asset Purchase
Agreement, the Security Agreements or the Promissory Note authorizes the
acceleration of the Promissory Note or any other Guaranteed Obligation;
 
(c)  there occurs an Event of Default (as defined in the Security Agreements)
under the Security Agreements;
 
(d)  any injunction, stay or the like that enjoins any acceleration, or demand
for the payment, observance or performance, of any Guaranteed Obligation that
would otherwise be required or permitted under the Asset Purchase Agreement or
the Promissory Note shall become effective; or
 
(e)  any Guaranteed Obligation shall be or be determined to be or become
discharged, disallowed, invalid, illegal, void or otherwise unenforceable
(whether by operation of any present or future law or by order of any court or
governmental agency) against the Buyer;
 
then (i) such Guaranteed Obligations shall, for all purposes of this Agreement,
be deemed (A) in the case of clause (d), to continue to be outstanding and in
full force and effect notwithstanding the unenforceability thereof against the
Buyer and (B) if such is not already the case, to have thereupon become
immediately due and payable and to have commenced bearing interest at the
post-default rate, and (ii) the Guaranteed Party may, with respect to such
Guaranteed

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Obligations, exercise all of the rights and remedies hereunder that would be
available to it during an Event of Default.
 
SECTION 1.3  Recovered Payments.    The Guaranteed Obligations shall be deemed
not to have been paid, observed or performed, and the Guarantor’s obligations
hereunder in respect thereof shall continue and not be discharged, to the extent
that any payment, observance or performance thereof by the Buyer or any other
guarantor, or out of the proceeds of any collateral, is recovered from or paid
over by or for the account of the Guaranteed Party for any reason, including as
a preference or fraudulent transfer or by virtue of any subordination (whether
present or future or contractual or otherwise) of the Guaranteed Obligations,
whether such recovery or payment over is effected by any judgment, decree or
order of any court or governmental agency, by any plan of reorganization or by
settlement or compromise by the Guaranteed Party (whether or not consented to by
the Buyer, the Guarantor or any other guarantor) of any claim for any such
recovery or payment over. The Guarantor hereby expressly waives the benefit of
any applicable statute of limitations and agrees that it shall be liable
hereunder with respect to any Guaranteed Obligation whenever such a recovery or
payment over thereof occurs.
 
SECTION 1.4  Nature of Guarantor’s Obligations.    The Guarantor’s obligations
hereunder (a) are absolute and unconditional, (b) constitute a guaranty of
payment and performance and not a guaranty of collection, (c) are as primary
obligor and not as a surety only, (d) shall be a continuing guaranty of all
present and future Guaranteed Obligations and all promissory notes and other
documentation given in extension or renewal or substitution for any of the
Guaranteed Obligations and (e) shall be irrevocable.
 
SECTION 1.5  No Release of Guarantor.    THE OBLIGATIONS OF THE GUARANTOR
HEREUNDER SHALL NOT BE REDUCED, LIMITED OR TERMINATED, NOR SHALL THE GUARANTOR
BE DISCHARGED FROM ANY THEREOF, FOR ANY REASON WHATSOEVER (other than, subject
to Sections 1.3 and 1.9, the payment, observance and performance of the
Guaranteed Obligations), including (and whether or not the same shall have
occurred or failed to occur once or more than once and whether or not the
Guarantor shall have received notice thereof):
 
(a)  (i) any extension of the time of payment, observance or performance of,
(ii) any amendment or modification of any of the other terms and provisions of,
(iii) any release, composition or settlement (whether by way of acceptance of a
plan of reorganization or otherwise) of, (iv) any subordination (whether present
or future or contractual or otherwise) of, or (v) any discharge, disallowance,
invalidity, illegality, voidness or other unenforceability of, the Guaranteed
Obligations;
 
(b)  (i) any failure to obtain, (ii) any release, composition or settlement of,
(iii) any amendment or modification of any of the terms and provisions of, (iv)
any subordination of, or (v) any discharge, disallowance, invalidity,
illegality, voidness or other unenforceability of, any other guaranties of the
Guaranteed Obligations;
 
(c)  (i) any failure to obtain or any release of, (ii) any failure to protect or
preserve, (iii) any release, compromise, settlement or extension of the time of
payment of any

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obligations constituting, (iv) any failure to perfect or maintain the perfection
or priority of any lien upon, (v) any subordination of any lien upon, or (vi)
any discharge, disallowance, invalidity, illegality, voidness or other
unenforceability of any lien or intended lien upon, any collateral now or
hereafter securing the Guaranteed Obligations or any other guaranties thereof;
 
(d)  any termination of or change in any relationship between the Guarantor and
the Buyer, including any such termination or change resulting from a change in
the ownership of the Guarantor or the Buyer or from the cessation of any
commercial relationship between the Guarantor and the Buyer;
 
(e)  any exercise of, or any election not or failure to exercise, delay in the
exercise of, waiver of, or forbearance or other indulgence with respect to, any
right, remedy or power available to the Guaranteed Party, including (i) any
election not or failure to exercise any right of setoff, recoupment or
counterclaim, (ii) any election of remedies effected by the Guaranteed Party,
including the foreclosure upon any real estate constituting collateral, whether
or not such election affects the right to obtain a deficiency judgment, and
(iii) any election by the Guaranteed Party in any proceeding under the
Bankruptcy Code of the application of Section 1111(b)(2) of such Code; and
 
(f)  ANY OTHER ACT OR FAILURE TO ACT OR ANY OTHER EVENT OR CIRCUMSTANCE THAT (i)
VARIES THE RISK OF THE GUARANTOR HEREUNDER OR (ii) BUT FOR THE PROVISIONS
HEREOF, WOULD, AS A MATTER OF STATUTE OR RULE OF LAW OR EQUITY, OPERATE TO
REDUCE, LIMIT OR TERMINATE THE OBLIGATIONS OF THE GUARANTOR HEREUNDER OR
DISCHARGE THE GUARANTOR FROM ANY THEREOF.
 
SECTION 1.6  Certain Waivers.    The Guarantor waives:
 
(a)  any requirement, and any right to require, that any right or power be
exercised or any action be taken against the Buyer, any other guarantor or any
collateral for the Guaranteed Obligations;
 
(b)  (i) notice of acceptance of and intention to rely on this Agreement, (ii)
notice of the making or renewal of any loans or other extensions of credit in
connection with or in furtherance of the Asset Purchase Agreement, and notice of
the incurrence or renewal of any other Guaranteed Obligations, (iii) notice of
any of the matters referred to in Section 1.5 and (iv) all other notices that
may be required by applicable Law or otherwise to preserve any rights against
the Guarantor under this Agreement, including any notice of default, demand,
dishonor, presentment and protest;
 
(c)  diligence;
 
(d)  any defense based upon, arising out of or in any way related to (i) any
claim that any election of remedies by the Guaranteed Party, including the
exercise by the Guaranteed Party of any rights against any collateral, impaired,
reduced, released or otherwise extinguished any right that the Guarantor might
otherwise have had against the Buyer or any other guarantor or against any
collateral, including any right of subrogation, exoneration, reimbursement or
contribution or right to obtain a deficiency judgment, (ii) any claim based

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upon, arising out of or in any way related to any of the matters referred to in
Section 1.5 and (iii) any claim that this Agreement should be strictly construed
against the Guaranteed Party; and
 
(e)  OTHER THAN BUYER’S OFFSET RIGHTS SET FORTH IN THE ASSET PURCHASE AGREEMENT
AND THE PROMISSORY NOTE, ALL OTHER DEFENSES UNDER APPLICABLE LAW THAT WOULD, BUT
FOR THIS CLAUSE (e), BE AVAILABLE TO THE GUARANTOR AS A DEFENSE AGAINST OR A
REDUCTION OR LIMITATION OF ITS OBLIGATIONS HEREUNDER.
 
SECTION 1.7  Independent Credit Evaluation.    The Guarantor has independently,
and without reliance on any information supplied by the Guaranteed Party, taken,
and will continue to take, whatever steps it deems necessary to evaluate the
financial condition and affairs of the Buyer, and the Guaranteed Party shall
have no duty to advise the Guarantor of information at any time known to it
regarding such financial condition or affairs.
 
SECTION 1.8  Subordination of Rights Against the Buyer, Other Guarantors and
Collateral.    All rights that the Guarantor may at any time have against the
Buyer, any other guarantor or any collateral for the Guaranteed Obligations
(including rights of subrogation, exoneration, reimbursement and contribution
and whether arising under applicable Law or otherwise), and all obligations that
the Buyer or any other guarantor may at any time have to the Guarantor, are
hereby expressly subordinated to the prior payment, observance and performance
in full of the Guaranteed Obligations. The Guarantor shall not enforce any of
the rights, or attempt to obtain payment or performance of any of the
obligations, subordinated pursuant to this Section 1.10 until the Guaranteed
Obligations have been paid, observed and performed in full, except that such
prohibition shall not apply to routine acts, such as the giving of notices and
the filing of continuation statements, necessary to preserve any such rights. If
any amount shall be paid to or recovered by the Guarantor (whether directly or
by way of setoff, recoupment or counterclaim) on account of any right or
obligation subordinated pursuant to this Section 1.8, such amount shall be held
in trust by the Guarantor for the benefit of the Guaranteed Party, not
commingled with any of the Guarantor’s other funds and forthwith paid over to
the Guaranteed Party, in the exact form received, together with any necessary
endorsements, to be applied and credited against, or held as security for, the
Guaranteed Obligations and the obligations of the Guarantor hereunder.
 
SECTION 1.9  Payments by the Guarantor.
 
(a)  Time, Place and Manner.    All payments due to the Guaranteed Party
hereunder shall be made to the Guaranteed Party at the Guaranteed Party’s office
or at such other address as the Guaranteed Party may designate by notice to the
Guarantor. A payment shall not be deemed to have been made on any day unless
such payment has been received by the Guaranteed Party, at the required place of
payment, in Dollars in funds immediately available to the Guaranteed Party, no
later than 12:00 noon (New York time) on such day.
 
(b)  No Reductions.    Subject to Buyer’s offset rights set forth in the Asset
Purchase Agreement and the Promissory Note, all payments due the Guaranteed
Party hereunder, and all of the other terms, conditions, covenants and
agreements to be observed and performed by the Guarantor hereunder, shall be
made, observed or performed by the Guarantor without any

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reduction or deduction whatsoever, including any reduction or deduction for any
set-off, recoupment, counterclaim (whether, in any case, in respect of an
obligation owed by the Guaranteed Party to the Guarantor, the Buyer or any other
guarantor and, in the case of a counterclaim, whether sounding in tort, contract
or otherwise) or tax.
 
(c)  Authorization to Charge Accounts.    The Guarantor hereby authorizes the
Guaranteed Party, if and to the extent any amount payable by the Guarantor
hereunder is not otherwise paid when due, to charge such amount against any or
all of the accounts of the Guarantor with the Guaranteed Party or any of its
Affiliates (whether maintained at a branch or office located within or without
the United States), with the Guarantor remaining liable for any deficiency.
 
(d)  Extension of Payment Dates.    Whenever any payment to the Guaranteed Party
hereunder would otherwise be due (except by reason of acceleration) on a day
that is not a Business Day, such payment shall instead be due on the next
succeeding Business Day. If the date any payment hereunder is due is extended
(whether by operation of this Agreement, applicable Law or otherwise), such
payment shall bear interest for such extended time at the rate of interest
applicable hereunder.
 
ARTICLE 2
 
CERTAIN REPRESENTATIONS AND WARRANTIES
 
The Guarantor represents and warrants as follows:
 
SECTION 2.1  Organization; Power; Qualification.    The Guarantor is a
corporation duly organized, validly existing and in good standing under the laws
of its jurisdiction of incorporation, has the corporate power and authority to
own its property and to carry on its business as now being and hereafter
proposed to be conducted and is duly qualified and in good standing as a foreign
corporation, and authorized to do business, in all jurisdictions in which the
character of its property or the nature of its business requires such
qualification or authorization, except for qualifications and authorizations the
lack of which, singly or in the aggregate, has not had and will not have a
Material Adverse Effect on the Guarantor.
 
SECTION 2.2  Authorization; Enforceability; Required Consents; Absence of
Conflicts.    The Guarantor has the power, and has taken all necessary action
(including, if a corporation, any necessary stockholder action) to authorize it,
to execute, deliver and perform in accordance with its terms this Agreement.
This Agreement has been duly executed and delivered by the Guarantor and is a
legal, valid and binding obligation of the Guarantor, enforceable against the
Guarantor in accordance with its terms, except as enforceability may be limited
by applicable bankruptcy, insolvency, reorganization, moratorium or similar laws
affecting the enforcement of creditors’ rights generally. The execution,
delivery and performance in accordance with its terms by the Guarantor of this
Agreement do not and (absent any change in any applicable Law or applicable
contract) will not (a) require any governmental approval or any other consent or
approval, including any consent or approval of the stockholders of the Guarantor
or any of its subsidiaries, to have been obtained or any governmental
registration to have been made, by the Guarantor or any of its subsidiaries, or
(b) violate, conflict with, result in a breach of, constitute a default under,
or result in or require the creation of any lien upon any assets of the
Guarantor

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under, (i) any contract to which the Guarantor or any of its subsidiaries is a
party or by which the Guarantor or any of its subsidiaries or any of their
respective properties may be bound or (ii) any applicable Law.
 
ARTICLE 3
 
CERTAIN COVENANTS
 
SECTION 3.1  Preservation of Existence and Franchises, Scope of Business,
Compliance with Law, Preservation of Enforceability.    From the Agreement Date
and until the Termination Date, the Guarantor shall: (a) preserve and maintain
its corporate existence and all of its other franchises, licenses, rights and
privileges, (b) engage only in businesses in substantially the same fields as
the businesses conducted on the Agreement Date, (c) comply with all applicable
Law and (d) take all action and obtain all consents and governmental approvals
required so that its obligations hereunder will at all times be legal, valid and
binding and enforceable in accordance with their respective terms, except that
clauses (a) (except insofar as it requires the Guarantor to preserve its
corporate existence) and (c) of this Section 3.1 shall not apply in any
circumstance where noncompliance, together with all other noncompliances with
this Section 3.1, will not have a Material Adverse Effect on the Guarantor.
 
ARTICLE 4
 
MISCELLANEOUS
 
SECTION 4.1  Notices and Deliveries.
 
(a)  Manner of Delivery.    All notices, communications and materials (including
all Information) to be given or delivered pursuant to this Agreement shall,
except in those cases where giving notice by telephone is expressly permitted,
be given or delivered in writing (which shall include telex and telecopy
transmissions). Demands under Section 1.1(b) may be by telephone. In the event
of a discrepancy between any telephonic notice and any written confirmation
thereof, such written confirmation shall be deemed the effective notice except
to the extent that the Guaranteed Party has acted in reliance on such telephonic
notice.
 
(b)  Addresses.    All notices, communications and materials to be given or
delivered pursuant to this Agreement shall be given or delivered at the
following respective addresses and telex, telecopier and telephone numbers and
to the attention of the following individuals or departments:
 
(i)  if to the Guarantor, to it at:
 
  Drew Scientific Group PLC
  Park Road, Barrow In Furness
  Cumbria, LA14 4QR
  United Kingdom
  Telecopier No.: 011-44-1229-432096
  Telephone No.: 011-44-1229-432089
  Attention: Michael J. Sipple-Asher

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(ii)  if to the Guaranteed Party, to it at the address or telex, telecopier or
telephone number and to the attention of the individual or department set forth
as the notice address for the Guaranteed Party in Section 7.3 of the Asset
Purchase Agreement;
 
or at such other address or telex, telecopier or telephone number or to the
attention of such other individual or department as the party to which such
information pertains may hereafter specify for the purpose in a notice to the
other specifically captioned “Notice of Change of Address”.
 
(c)  Effectiveness.    Each notice and communication and any material to be
given or delivered pursuant to this Agreement shall be deemed so given or
delivered (i) if sent by registered or certified mail, postage prepaid, return
receipt requested, on the third Business Day after such notice, communication or
material, addressed as above provided, is delivered to a United States post
office and a receipt therefor is issued thereby, (ii) if sent by any other means
of physical delivery, when such notice, communication or material is delivered
to the appropriate address as above provided, (iii) if sent by telex, when such
notice, communication or material is transmitted to the appropriate number
determined as above provided in this Section 4.1 and the appropriate answer-back
is received, (iv) if sent by telecopier, when such notice, communication or
material is transmitted to the appropriate telecopier number as above provided
and is received at such number and (v) if given by telephone, when communicated
to the individual or any member of the department specified as the individual or
department to whose attention notices, communications and materials are to be
given or delivered, except that (A) notices of a change of address, telex,
telecopier or telephone number or individual or department to whose attention
notices, communications and materials are to be given or delivered shall not be
deemed given until received and (B) notices, communications and materials to be
given or delivered to the Guaranteed Party pursuant to this Agreement shall not
be deemed given or delivered until received by the officer of the Guaranteed
Party responsible, at the time, for the administration of the Promissory Note.
 
(d)  Reasonable Notice.    Any requirement under applicable Law of reasonable
notice by the Guaranteed Party to the Guarantor of any event in connection with,
or in any way related to, the Asset Purchase Agreement or the Promissory Note,
or the exercise by the Guaranteed Party of any of its rights thereunder shall be
met if notice of such event is given to the Guarantor in the manner prescribed
above at least 10 days before (i) the date of such event or (ii) the date after
which such event will occur.
 
SECTION 4.2  Expenses; Indemnification.    The Guarantor shall:
 
(a)  pay or reimburse the Guaranteed Party for all reasonable costs and expenses
(including fees and disbursements of legal counsel, appraisers, accountants and
other experts employed or retained by the Guaranteed Party) incurred by the
Guaranteed Party in connection with, arising out of, or in any way related to
protecting, preserving, exercising or enforcing any of its rights under or
related to this Agreement; and
 
(b)  indemnify and hold each Indemnified Person harmless from and against all
losses (including judgments, penalties and fines) suffered, and pay or reimburse
each Indemnified Person for all costs and expenses (including fees and
disbursements of legal counsel

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and other experts employed or retained by such Indemnified Person) incurred, by
such Indemnified Person in connection with, arising out of, or in any way
related to (i) any Guaranty Agreement Related Claim (whether asserted by such
Indemnified Person or the Guarantor or any other Person), including the
prosecution or defense thereof and any litigation or proceeding with respect
thereto (whether or not, in the case of any such litigation or proceeding, such
Indemnified Person is a party thereto), or (ii) any investigation, governmental
or otherwise, arising out of, related to, or in any way connected with, this
Agreement or the relationship established hereunder, except that the foregoing
indemnity shall not be applicable to any loss suffered by any Indemnified Person
to the extent such loss is determined by a judgment of a court that is binding
on the Guarantor and such Indemnified Person, final and not subject to review on
appeal, to be the result of acts or omissions on the part of such Indemnified
Person constituting (A) willful misconduct, (B) knowing violations of law or (C)
in the case of claims by the Guarantor against such Indemnified Person, such
Indemnified Person’s failure to observe any other standard applicable to it
under any of the other provisions of this Agreement or, but only to the extent
not waivable thereunder, Applicable Law.
 
SECTION 4.3  Amounts Payable Due upon Request for Payment.    All amounts
payable by the Guarantor under Section 4.2 and under the other provisions of
this Agreement shall, except as otherwise expressly provided, be immediately due
upon request for the payment thereof.
 
SECTION 4.4  Remedies of the Essence.    The various rights and remedies of the
Guaranteed Party under this Agreement are of the essence of this Agreement, and
the Guaranteed Party shall be entitled to obtain a decree requiring specific
performance of each such right and remedy.
 
SECTION 4.5  Rights Cumulative.    Each of the rights and remedies of the
Guaranteed Party under this Agreement shall be in addition to all of its other
rights and remedies under this Agreement and applicable Law, and nothing in this
Agreement shall be construed as limiting any such rights or remedies.
 
SECTION 4.6  Amendments; Waivers.    Any term, covenant, agreement or condition
of this Agreement may be amended, and any right under this Agreement may be
waived, if, but only if, such amendment or waiver is in writing and is signed by
the Guaranteed Party and, in the case of an amendment, by the Guarantor. Unless
otherwise specified in such waiver, a waiver of any right under this Agreement
shall be effective only in the specific instance and for the specific purpose
for which given. No election not to exercise, failure to exercise or delay in
exercising any right, nor any course of dealing or performance, shall operate as
a waiver of any right of the Guaranteed Party under this Agreement or applicable
Law, nor shall any single or partial exercise of any such right preclude any
other or further exercise thereof or the exercise of any other right of the
Guaranteed Party under this Agreement or applicable Law.

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SECTION 4.7 Assignments.
 
(a)  Assignments.
 
(i)  Neither this Agreement nor any of the obligations of Guarantor hereunder
may be delegated or assigned (whether by operation of law or otherwise) by
Guarantor without the express prior written consent of the Guaranteed Party, and
the consent to any proposed assignment shall not constitute consent to any
subsequent proposed assignment. Any attempted assignment in contravention hereof
shall be null and void and of no force or effect. No assignment of any
obligation under this Agreement shall release the Guarantor therefrom unless the
Guaranteed Party shall have consented to such release in a writing specifically
referring to the obligation from which the Guarantor is to be released.
 
(ii)    The Guaranteed Party shall have the right to assign this Agreement and
its rights hereunder and without seeking or obtaining any consent or approval of
Guarantor; provided, however, that any such assignment shall be an assignment of
the Promissory Note and this Agreement in their entirety.
 
(b)  Rights of Assignees.    Each assignee of the rights of the Guaranteed Party
under this Agreement, if and to the extent the applicable assignment agreement
so provides, (i) shall, with respect to its assignment, be entitled to all of
the rights of the Guaranteed Party, subject to any conditions imposed on the
Guaranteed Party hereunder with respect thereto, and (ii) may exercise any and
all rights of set-off or banker’s lien with respect thereto.
 
SECTION 4.8  Governing Law.    The rights and duties of the Guarantor and the
Guaranteed Party under this Agreement (including matters relating to the Maximum
Permissible Rate) shall, pursuant to New York General Obligations Law Section
5-1401, be governed by the laws of the State of New York, without regard to its
conflicts of laws principles.
 
SECTION 4.9  Judicial Proceedings; Waiver of Jury Trial.    Any judicial
proceeding brought against the Guarantor with respect to any Guaranty Agreement
Related Claim may be brought in any court of competent jurisdiction in the
County of San Diego, State of California, and, by execution and delivery of this
Agreement, the Guarantor (a) accepts, generally and unconditionally, the
nonexclusive jurisdiction of such courts and any related appellate court and
agrees to be bound by any final judgment rendered thereby in connection with any
Guaranty Agreement Related Claim and (b) irrevocably waives any objection it may
now or hereafter have as to the venue of any such proceeding brought in such a
court or that such a court is an inconvenient forum. The Guarantor hereby waives
personal service of process and consents that service of process upon it may be
made by certified or registered mail, return receipt requested, at its address
specified or determined in accordance with the provisions of Section 4.1(b), and
service so made shall be deemed completed on the third Business Day after such
service is deposited in the mail. Nothing herein shall affect the right of the
Guaranteed Party or any other Indemnified Person to serve process in any other
manner permitted by law or shall limit the right of the Guaranteed Party or any
other Indemnified Person to bring proceedings against the Guarantor in the
courts of any other jurisdiction. Any judicial proceeding by the Guarantor
against the Guaranteed Party involving any Guaranty Agreement Related Claim
shall be brought only in a court located in the County of San Diego, State of
California. THE GUARANTOR

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AND THE GUARANTEED PARTY HEREBY WAIVE TRIAL BY JURY IN ANY JUDICIAL PROCEEDING
TO WHICH THEY ARE BOTH PARTIES INVOLVING ANY GUARANTY AGREEMENT RELATED CLAIM.
 
SECTION 4.10  Severability of Provisions.    Any provision of this Agreement
that is prohibited or unenforceable in any jurisdiction shall, as to such
jurisdiction, be ineffective to the extent of such prohibition or
unenforceability without invalidating the remaining provisions hereof or
affecting the validity or enforceability of such provision in any other
jurisdiction. To the extent permitted by applicable Law, the Guarantor hereby
waives any provision of applicable Law that renders any provision hereof
prohibited or unenforceable in any respect.
 
SECTION 4.11  Counterparts.    This Agreement may be signed in any number of
counterparts, each of which shall be an original, with the same effect as if the
signatures thereto were upon the same instrument.
 
SECTION 4.12  Survival of Obligations.    Except as otherwise expressly provided
herein, the rights and obligations of the Guarantor, the Guaranteed Party and
the other Indemnified Persons hereunder shall survive the Termination Date.
 
SECTION 4.13  Entire Agreement.    This Agreement embodies the entire agreement
between the Guarantor and the Guaranteed Party relating to the subject matter
hereof and supersedes all prior agreements, representations and understandings,
if any, relating to the subject matter hereof.
 
SECTION 4.14  Successors and Assigns.    All of the provisions of this Agreement
shall be binding upon and inure to the benefit of the parties hereto and their
respective successors and assigns.
 
ARTICLE 5
 
INTERPRETATION
 
SECTION 5.1  Definitional Provisions.
 
(a)  Certain Terms Defined by Reference.    Except in the case of “Agreement”,
“Agreement Date” and “Representation and Warranty” and as otherwise specified
herein, all terms defined in the Asset Purchase Agreement and the Promissory
Note are used herein with the meanings therein ascribed to them.
 
(b)  Other Defined Terms.    For purposes of this Agreement:
 
“Agreement” means this Agreement, including all schedules, annexes and exhibits
hereto.
 
“Agreement Date” means the date set forth as such on the last signature page
hereof.
 
“Asset Purchase Agreement” means the Asset Purchase Agreement of even date
herewith, among Guarantor, Danam Acquisition Corp. and Synbiotics Corporation.

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“Business Day” means any day other than a Saturday, Sunday or any other day on
which banks in New York City are authorized to close.
 
“Buyer” means Danam Acquisition Corp., a Delaware corporation and an indirect,
wholly-owned subsidiary of Guarantor.
 
“Guaranteed Obligations” means all obligations of the Buyer owing to, or in
favor or for the benefit of, or purporting to be owing to, or in favor or for
the benefit of, the Guaranteed Party, or any Person or Persons that become the
Guaranteed Party by reason of any succession or assignment at any time after the
Agreement Date, under the Asset Purchase Agreement, the Security Agreements and
the Promissory Note (after taking into account such setoffs as may be permitted
under the Asset Purchase Agreement), in each case (i) WHETHER NOW EXISTING OR
HEREAFTER ARISING OR ACQUIRED and (ii) WHETHER OR NOT AN ALLOWABLE CLAIM AGAINST
THE BUYER UNDER THE BANKRUPTCY CODE OR OTHERWISE ENFORCEABLE AGAINST THE BUYER,
AND INCLUDING, IN ANY EVENT, INTEREST AND OTHER LIABILITIES ACCRUING OR ARISING
AFTER THE FILING BY OR AGAINST THE BUYER OF A PETITION UNDER THE BANKRUPTCY CODE
OR THAT WOULD HAVE SO ACCRUED OR ARISEN BUT FOR THE FILING OF SUCH A PETITION.
 
“Guaranteed Party” means Synbiotics Corporation, a California corporation.
 
“Guaranteed Party’s Office” means the address of the Guaranteed Party determined
in accordance with the provisions of Section 4.1(b).
 
“Guarantor” means Drew Scientific Group PLC, a corporation organized under the
laws of England and Wales.
 
“Guaranty Agreement Related Claim” means any claim (whether civil, criminal or
administrative and whether sounding in tort, contract or otherwise) in any way
arising out of, related to, or connected with, this Agreement or the
relationship established hereunder, whether such claim arises or is asserted
before or after the Agreement Date or before or after the Termination Date.
 
“Indemnified Person” means any Person that is, or at any time was, the
Guaranteed Party, an Affiliate of the Guaranteed Party, or a director, officer,
employee or agent of any such Person.
 
“Promissory Note” means the secured promissory note in the face amount of
$500,000 executed by Buyer pursuant to the Asset Purchase Agreement.
 
“Representation and Warranty” means each representation or warranty made
pursuant to or under (i) Article 2 or any other provision of this Agreement or
(ii) any amendment to, or waiver of rights under, this Agreement, WHETHER OR
NOT, IN THE CASE OF ANY REPRESENTATION OR WARRANTY REFERRED TO IN CLAUSE (i) OR
(ii) OF THIS DEFINITION (EXCEPT, IN EACH CASE, TO THE EXTENT OTHERWISE EXPRESSLY
PROVIDED), THE INFORMATION THAT IS THE SUBJECT MATTER THEREOF IS WITHIN THE
KNOWLEDGE OF THE GUARANTOR.

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“Security Agreements” means the Security Agreement of even date herewith between
Danam Acquisition Corp. and Synbiotics Corporation and the Patent and Trademark
Security Agreement of even date herewith between Danam Acquisition Corp. and
Synbiotics Corporation.
 
“Termination Date” means the date on which all Guaranteed Obligations are fully
paid, satisfied, observed and performed in all respects.
 
SECTION 5.2  Other Interpretative Provisions.
 
(a)  Except as otherwise specified herein, all references herein (i) to any
Person shall be deemed to include such Person’s successors and assigns, (ii) to
any applicable Law defined or referred to herein shall be deemed references to
such applicable Law or any successor applicable Law as the same may have been or
may be amended or supplemented from time to time and (iii) to any document or
contract defined or referred to herein shall be deemed references to such
document or contract (and, in the case of any instrument, any other instrument
issued in substitution therefor) as the terms thereof may have been or may be
amended, supplemented, waived or otherwise modified from time to time.
 
(b)  When used in this Agreement, the words “herein”, “hereof” and “hereunder”
and words of similar import shall refer to this Agreement as a whole and not to
any provision of this Agreement, and the words “Article”, “Section”, “Annex”,
“Schedule” and “Exhibit” shall refer to Articles and Sections of, and Annexes,
Schedules and Exhibits to, this Agreement unless otherwise specified.
 
(c)  Whenever the context so requires, the neuter gender includes the masculine
or feminine, the masculine gender includes the feminine, and the singular number
includes the plural, and vice versa.
 
(d)  Any item or list of items set forth following the word “including”,
“include” or “includes” is set forth only for the purpose of indicating that,
regardless of whatever other items are in the category in which such item or
items are “included”, such item or items are in such category, and shall not be
construed as indicating that the items in the category in which such item or
items are “included” are limited to such items or to items similar to such
items.
 
(e)  Each authorization in favor of the Guaranteed Party or any other Person
granted by or pursuant to this Agreement shall be deemed to be irrevocable and
coupled with an interest.
 
(f)  Except as otherwise indicated, any reference herein to the “Guaranteed
Obligations”, the “Asset Purchase Agreement” or the “Promissory Note” or any
other collective or plural term shall be deemed a reference to each and every
item included within the category described by such collective or plural term,
so that (i) a reference to the “Guaranteed Obligations” shall be deemed a
reference to any or all of the Guaranteed Obligations; and (ii) a reference to
the “obligations” under the “Asset Purchase Agreement” or the “Promissory Note”
shall be deemed a reference to each and every obligation thereunder.

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(g)  Except as otherwise specified therein, all terms defined in this Agreement
shall have the meanings herein ascribed to them when used in any certificate,
opinion or other document delivered pursuant hereto or thereto.
 
SECTION 5.3  Representations and Warranties.    All Representations and
Warranties shall be deemed made (a) in the case of any Representation and
Warranty contained in this Agreement at the time of its initial execution and
delivery, at and as of the Agreement Date, and (b) in the case of any particular
Representation and Warranty, wherever contained, at such other time or times as
such Representation and Warranty is made or deemed made in accordance with the
provisions of this Agreement or the document pursuant to, under or in connection
with which such Representation and Warranty is made or deemed made.
 
SECTION 5.4  Captions.    Captions to Articles, Sections and subsections of, and
Annexes, Schedules and Exhibits to, this Agreement are included for convenience
of reference only and shall not constitute a part of this Agreement for any
other purpose or in any way affect the meaning or construction of any provision
of this Agreement.
 
IN WITNESS WHEREOF, the parties hereto have caused this Agreement to be executed
by their duly authorized officers all as of the Agreement Date.
 
DREW SCIENTIFIC GROUP PLC
By:
 
/s/    MICHAEL J. S. ASHER

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Michael J. S. Asher
CEO

 
SYNBIOTICS CORPORATION
By:
 
/s/    PAUL A. ROSINACK       

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Paul A. Rosinack
President & CEO

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