<PAGE>   1
                                                                    Exhibit 10.5


AGREEMENT FOR THE OPERATION OF VETERINARY
LABORATORIES, INC.'S LENEXA FACILITY AND SPARHAWK LAB  OF K.C.
AS A JOINT VENTURE

THIS AGREEMENT is made this 1 day of December, 1992, by and between CHEMDEX,
INC., a Kansas Corporation, (hereinafter "Chemdex"), VETERINARY LABORATORIES,
INC., a Kansas Corporation, (hereinafter "Vet Labs"), and SPARHAWK LABORATORIES,
INC., a Missouri Corporation, (HEREINAFTER SPARHAWK"), for the purpose of
forming and operating a Joint Venture between Vet Labs and Sparhawk and
authorizing the Joint Venture to Operate the Vet Labs' Lenexa facility and
Sparhawk Laboratories facilities.

WITNESSETH;

In consideration of the terms, conditions, and covenants hereinafter set forth,
the parties hereto mutually agree as follows:

1. Name. The veterinary pharmaceutical manufacturing facility presently located
at 12340 Santa Fe Drive, Lenexa, Kansas, will continue to operate under the name
of Veterinary Laboratories, Inc. (hereinafter "Vet Labs").

2. Separate Legal Entity.

(A) Vet Labs will remain a separate and distinct legal entity from Sparhawk and
Vet Labs shall retain ownership of all licensing agreements for NADA and DEA
products, as well as all lands, buildings, fixtures, equipment and all personal
property presently located at 12340 Santa Fe Drive, Lenexa, Kansas, and all
other assets of Vet Labs existing prior to the formation of the Joint Venture
whether situated thereon or otherwise situated (hereinafter "Vets Labs'
Facility" and/or "Vet Labs' Assets"), subject to the more specific terms of this
Agreement.

(B) Sparhawk will remain a separate and distinct legal entity from Vet Labs and
Sparhawk shall retain ownership of all licensing agreements as well as all
lands, building, fixtures, equipment and all personal property presently located
at 22 N. 6th St., Kansas City, Kansas and all other assets of Sparhawk existing
prior to the formation of the Joint Venture whether situated thereon or
otherwise situated (hereinafter Sparhawk facility and/or Sparhawk assets),
subject to the more specific terms of this Agreement.

(C) As Vet Labs, Sparhawk and the joint venture are each separate legal
entities, it is critical that the accounting system and records be maintained
separately.

3. Joint Venture. The parties hereby form a Joint Venture (the "Joint Venture")
to be governed by the terms and conditions set forth in this Agreement.

4. Name. The Joint Venture shall hereafter use the name "Vet/Sparhawk" or such
other names as the Joint Venturers shall determine.

5. Purpose. The purpose of the Joint Venture is to manage the Vet Labs' Facility
and Sparhawk Facility as a Joint Venture, with the Joint Venture providing day
to day management, and personnel as set forth herein and Vet Labs contributing
the use of the Vet Labs' Facility and Sparhawk contributing the use of the
Sparhawk Facility. Vet Labs and Sparhawk hereby transfer unto the Joint Venture
those current assets and liabilities set forth on Exhibit "A", a copy of which
is attached hereto and made a part hereof by reference.

6. Management of Joint Venture. The Joint Venture shall be managed by a Policy
Committee containing five(5) members, two (2) of which will be chosen by
Sparhawk and three (3) of which will be chosen by the 

<PAGE>   2

Board of Directors of Vet Labs.

7. Officers of Vet Labs. Bert Hughes shall serve as President of Vet Labs And
John Bascom shall serve as Vice President of Vet Labs, subject at all time to 
the control, discretion and supervision of the Board of Directors of Vet Labs, 
or until removal or resignation.

8. Day to Day Operation. Bert Hughes shall be designated as the person who has
the daily management responsibilities of the Joint Venture, but subject to the
direction, control and at the discretion of the Policy Committee of the Joint
Venture or until removal or resignation. John Bascom shall assist Bert Hughes
and work under his direction but also subject to the direction, control, and at
the discretion of the Policy Committee, or until removal or resignation.

9. Authority to Conduct Business of Joint Venture. The Joint Venture as hereby
authorized to make all purchases, sales and maintain all inventories and other
accounts for the joint venture under the Sparhawk Labs and Vet Labs name. As
hereinafter directed, only for the purpose of operating the Vet Labs' Facility
and Sparhawk's Facilities. All operating cash accounts should be established by
the joint venture and all costs of the joint venture should be disbursed from
these accounts. Management of Sparhawk will coordinate the filing of all legal
documents and forms necessary for the joint venture to operate.

10. Management of Vet Labs' Facility.

a. The Joint Venture shall manage and conduct, subject to the general policy and
supervision of the Policy Committee, the affairs of the Vet Labs' Facility,
Sparhawk's Facilities and the Joint Venture (excluding general policy decisions,
new investments, corporate reorganization, borrowing, corporate refinancing and
the like, except as may be specifically authorized from time to time by the
Board or Directors of respective entities and the Joint Venture Policy
Committee) in accordance with the usual practice of trade and as further herein
provided.

b. Sparhawk shall have the right to determine and control all day-to-day
management decisions relating to personnel at Joint Venture Sparhawk and the Vet
Labs' Facility, including all hiring and termination of employees. All employees
at the Vet Labs' Facility will accountable to and will report directly to Bert
Hughes and/or John Bascom. Bert Hughes will be accountable to the Board of
Directors and will report directly to the Board of Directors and/or its
Representative. Sparhawk will hire and pay, on behalf of the Joint Venture and
maintain responsibility for the supervision and direction of all employees.
Joint will reimburse only direct labor expenses to Sparhawk. No override or
other administrative costs may be charged by Sparhawk. All employees at the Vet
Labs' Facility shall be considered employees of Sparhawk and Sparhawk will
maintain all health insurance, pay workmen's compensation and payroll taxes, and
charges associated with the Joint Venture. Sparhawk should set up a payroll
account and all payroll and payroll related costs should be disbursed from this
account. Sparhawk will then invoice and be reimbursed by the joint venture. The
invoice should reflect a breakout of period and product cost.

c. It is hereby acknowledged that Vet Labs is a wholly owned subsidiary on
Chemdex. Joint Venture will counsel with Chemdex on any major issue and keep
Chemdex informed of any regulatory or economic issue pertaining to Vet Labs, the
Vet Labs' Facility or Sparhawk.

d. All checks, notes and contracts, either issued by or binding the Joint
Venture or Vet Labs, will require two (2) signatures, one from the designated
signatory of Vet Labs (hereinafter "Vet Labs' Signatory") and the second from
Sparhawk.

e. At Sparhawk's option, the logo of Sparhawk may be printed on all paperwork
together with the logo of Vet Labs. 


                                      2
<PAGE>   3

f. All invoices and other paperwork must be addressed under Vet Labs' name only.
The telephone will be answered as Vet Labs or such name as determine by a
representative of the Policy Committee.

g. Depreciation of plant equipment is calculated in accordance with Generally
Accepted Accounting Principals and will be billed to the joint venture on a rate
equal to the depreciation expense recorded in Sparhawk and Vet Labs.

11. Inspection and Audit.

All documents pertaining in any way to the operation or finances of Vet Labs,
Joint Venture, or Sparhawk, including, but not limited to, accounts payable,
accounts receivable, and bank reconciliations and statements may be inspected
and/or audited by the authorized representative of Chemdex (hereinafter
"Chemdex' Representative") at any time.

12. Access/Concurrent Use.

Chemdex or the Chemdex Representative shall have access to and use of Vet Labs'
facilities as long as such use does not violate regulatory compliance guidelines
and/or disturb normal production.

13. Production.

a. All products manufactured at Vet Labs' or Sparhawk facilities will be labeled
under the Vet Lab/Sparhawk private label or other private label, at the
discretion of the Policy Committee.

b. At its discretion, the Joint Venture will use its best efforts to manufacture
all products currently or previous marketed, except for parenterals. Joint
Venture shall commence production in an expeditious manner, subject to
regulatory compliance. Sparhawk will use its best efforts to see that production
is in strict compliance with regulatory guidelines.

c. Joint Venture shall manufacture all products at either the Vet Labs facility,
or Sparhawk's Kansas facilities currently in operation. No other production
facilities shall be used without prior written consent of both Sparhawk and Vet
Labs. All such products manufactured for the Joint Venture (at both locations)
will be invoiced through Joint Venture only. A representative of Chemdex will be
allowed to review such invoices, at the Joint Ventures facility and the Sparhawk
facilities. d. When calculating profits of the Joint Venture, Sparhawk will not
deduct any payments made to a Sparhawk shareholder as a dividend.

e. Joint Venture agrees to manufacture Bulk Iron to meet the requirements of
Chemdex, with no labor or other charge to Chemdex, except for costs of raw
materials and packaging costs, freight in brokerage fees for the production of
the Bulk Iron, which Chemdex shall pay. A separate contract to this effect will
be executed by Chemdex and the Joint Venture.

f. Sparhawk agrees to use its best efforts to validate the manufacture of 100
ml. glass or other injectable production upon completion of all process
validations and other injectable production upon completion of all process
validations and other regulator compliance.

14.  Profit and Cost Participation.

a. Pre-tax net profits or losses generated from the production of non-sterile
products will allocated seventy percent (70%) to Sparhawk and thirty
percent(30%) to Vet Lab.

b. Vet Labs and Sparhawk shall share equally all pre-tax profits or losses for
the sale of non-sterile and injectable (once sales of injectables has
commenced). In this case, the above paragraph 14(a) shall not apply.



                                      3
<PAGE>   4

c. All tax profits generated from all Bulk Iron sales will be allocated to
Chemdex. Bulk Iron sales and related raw material costs will be accounted for
separately under Chemdex.

d. Chemdex will supply all raw material for the production of Bulk Iron at its
cost.

e. Chemdex will sell Bulk Iron to the joint venture at the some price as other
commercial account.

f. Sparhawk management shall use its best effort to maintain adequate financing
and positive cash flow in all operations.

g. Sparhawk agrees not to charge Vet Labs or joint venture a management fee of
any kind, but Bert Hughes and John Bascom will each be allowed to draw Forty
Five Thousand Dollars ($45,000) per annum as their salaries from joint venture
on a biweekly pay period. Salaries will not be raised without prior approval of
Chemdex. Such approval shall not be unreasonably withheld.

h. Vet Labs will not receive any supplement payment from the Joint Venture for
the use of the Vet Labs' Facility until a total of Twenty Thousand Dollars
($20,000) net profit are generated per month. After monthly net profit
(calculated prior to the profit (loss) participation at Section 14a and b) has
attained Twenty Thousand Dollars ($20,000.00) supplemental bonus shall be
charged in the following monthly amount thereafter:

1) Ten percent (10%) of profit between Twenty Thousand Dollars ($20,000.00) to
Twenty Five Thousand Dollars ($25,000.00);

2) Fifteen percent (15%) of profit between Twenty Five Thousand One Dollars
($25,001.00) to Thirty Thousand Dollars ($30,000.00);

3)Twenty percent (20%) of profit between Thirty Thousand One Dollars
($30,001.00) to Thirty Five Thousand Dollars ($35,00.00);

4) Twenty five percent (25%) of profit between Thirty Five Thousand One Dollars
($35,001.00) to Forty Thousand Dollars ($40,000.00); and

5) Thirty percent (30%) of profit above Forty Thousand One Dollars($40,001.00).

In any case, the maximum rent shall be Fifteen Thousand Dollars ($15,000.00) per
month.

15. Option to Purchase.

Vet Labs hereby grants unto Sparhawk the option to purchase forty percent (40%)
of the assets held by Vet Labs. This option shall come into existence on the
third (3rd) anniversary of the execution of this Agreement and shall remain in
force through the Tenth (10th) anniversary of the execution of this Agreement at
which time the option to purchase is terminated. The purchase price shall be
determined to be the fair market value of the Vet Labs and Building and
Equipment, plus the sum of One Million Dollars ($1,000,000.00) which shall be
paid for goodwill and the acquisition of NANA's and licenses held by Vet Labs.
The fair market value of the Vet Labs' Assets shall be calculated by a
disinterested third (3rd) party or entity mutually acceptable to Vet Labs and
Sparhawk.

16.  Term.

This Joint Venture shall continue for a period of ten (10) years from the date
of this Agreement and thereafter until terminated by this Agreement. Upon
termination, all rights to license agreements NADA and DEA products, and all
other proprietary rights of Vet Labs, and Sparhawk including the Vet Labs and



                                      4
<PAGE>   5

Sparhawk Facility and Vet Labs, Sparhawk Assets, shall be retained by Vet Labs,
and Sparhawk except as otherwise set forth herein.

17.  Joint Venturer's Interest in Property.

a. A Joint Venturer's "interest in the Joint Venture" includes its interest in
the Joint Venture's capital, profits, losses and distributions, as well as its
rights in specific Joint Venture property.

b.  The term "Joint Venturer" refers to each of Sparhawk and Vet Labs.

18.  Principal Place of Business.

The Joint Venture's principal place of business initially shall be at 12340
Santa Fe Drive, Lenexa, Kansas.

19. Capital Contributions. On or before closing, the Joint Venturers shall make
initial capital contributions as follows: All accounts receivable, inventory,
and cash according to the attached Exhibit "B".

20. Capital Accounts. A separate capital account shall be maintained to each
joint venture. No joint venture shall be entitled to receive interest on its
capital account balance. Each joint venturer's and transferee's allocated share
of Joint Venture profits and losses shall be credited or debited to its capital
account. All Joint Venture distributions of cash or property to any joint
venturer or transferee shall be debited to the distributee's capital account,
except distributions in repayment of loans made to the Joint Venture, salary
payments, expense reimbursements and any other distributions which the joint
venturers shall determine are not in reduction of the distributee's capital
account. Capital accounts shall be maintained in the same proportion as the
joint venture share in profit and losses.

21. Distributions. It is anticipated that the Joint Venture will retain earnings
& cash. If from time to time the joint venturers shall determine that the Joint
Venture has cash in excess of its needs, such excess cash shall be distributed
to portion of capital accounts.

22. Additional Capital Contributions. Additional capital funded by Joint Venture
shall be in the ratio of their respective capital accounts.

23. Profit and Loss Determination. Joint Venture profits and losses shall be
determined at the end of each fiscal year by the use of generally accepted
accounting principles. For the purpose of Joint Venture accounting and income
tax reporting, the Joint Venture shall operate on a January 31 fiscal year.

24. Accounting Records and Bank Accounts. The Joint Venture shall maintain
complete and accurate books and records of all Joint Venture transactions. Such
books and records shall be open at any time for inspection by any Joint Venturer
or Chemdex or its agent at such parties' expense. The Joint Venture shall
prepare monthly a statement showing the financial condition of the Joint Venture
and its profits and losses from operation. Copies of such statement shall be
promptly furnished to each joint venturer and Chemdex.

25. Transfer or Joint Venturer's Interest.

a. No Joint Venturer or transferee shall voluntarily or involuntarily transfer
all or any portion of its interest in the Joint Venture without the prior
consent of all of the Joint Venturers, and any act in violation of this
restriction shall be null and void, except as otherwise provided by law.

b. Upon dissolution or other cessation to exist as a legal entity of a Joint
Venturer (but not upon a statutory merger or consolidation), or upon the
bankruptcy or insolvency of a Joint Venturer, or upon any other involuntary
transfer by operation of law or otherwise of all or any portion of a Joint
Venturer's or transferee's interest in the Joint Venture, or if all or any
portion of a Joint Venturer's or transferee's interest in Joint Venture, is
deemed by law to have been transferred, the Joint Venture shall not be
terminated and its tax year shall not close; rather, the trustee, receiver,
court, agency, person, or other successor interest (a 



                                      5
<PAGE>   6

"Transferee") of such Joint Venturer's or transferee shall succeed to such Joint
Venturer's or transferee's interest in the Joint Venture's profits to the extent
so transferred; provided such transferee shall be a mere transferee (and not a
Joint Venturer) with respect to the interest so transferred.

c. Any person who acquires by a transfer of all or any part of a Joint
Venturer's or transferee's interest in the Joint Venture shall be subject to and
bound by this Agreement as if it were an original party hereto; and no such
person shall become an additional or substituted Joint Venturer.

26. Joint Venturer's Meetings; Policy Committee's Meetings.

A meeting of the Joint Venturers may be called at any time by a Joint Venturer
by giving each and every Joint Venturer written notice of the time and place of
such meeting, which notice must be given to all Joint Venturers at least ten
(10) days before the date of such meeting. Any such notice may be waived by the
Joint Venturers entitled thereof by signing a written waiver of notice, either
before or after the time of such meeting, and such waiver shall be deemed the
equivalent of such Joint Venturer's receipt of timely formal notice of the
meeting. A Joint Venturer's attendance in person or by representative at a
meeting shall constitute such Joint Venturer's waiver of notice thereof unless
the meeting is attended for the express purpose, stated at the opening of the
meeting, or objecting to the transaction of any business because the meeting is
not lawfully called. Each meeting of the Joint Venturers shall be held in
Lenexa, Kansas, unless the Joint Venturers agree otherwise and at a reasonably
convenient time and place.

27. Representations and Warranties of Sparhawk. Sparhawk represents and warrants
to Vet Labs and Chemdex and to the Joint Venture as of the date hereof, and also
as of the Closing, as follows:

a. Sparhawk is a corporation duly organized and validly existing under the laws
of the State of Missouri. Sparhawk has the full legal right, power and authority
to enter into this Agreement and to perform its obligations hereunder.

All actions necessary to authorize Sparhawk to enter into this Agreement to
undertake its duties hereunder have been duly and properly taken. This Agreement
is the legal, valid and binding obligation of Sparhawk, enforceable in
accordance with its terms.

b. The execution and delivery of this Agreement by Sparhawk and the performance
of its obligations hereunder will not contravene or conflict with any law,
order, rule or regulation presently in effect and will not conflict with or
result in a breach of any of the terms or provisions of, or constitute a default
under, or result in the creation or imposition of any lien, charge or
encumbrance upon any of the property or assets of Sparhawk pursuant to the terms
of, any agreement or instrument to which Sparhawk is a party or by which it is
bound or to which any of its property or assets are subject. Subject performance
by Sparhawk will not violate any provision of its charter or bylaws.

c. There are not actions, suits, claims, proceedings or investigations pending
or threatened with respect to the business or properties of Sparhawk.

d. Sparhawk has complied in all material respects with all laws, ordinances,
licensing requirements, regulations and orders applicable to the business being
conducted by it and has filed with the proper authorities all other required
statements, returns and reports.

28. Chemdex and Vet Labs Representations and Warranties.

Chemdex and Vet Labs represent and warrant to Sparhawk and the Joint Venture as
follows:

a. Vet Labs and Chemdex are corporations duly organized and validly existing
under the laws of the State 


                                      6
<PAGE>   7

of Kansas. Vet Labs and Chemdex have the corporate power to own and lease its
properties and carry on its business as and where now presently being conducted.
Vet Labs and Chemdex have the full legal right, power and authority to enter
into this Agreement and to perform its obligations hereunder. All actions
necessary to authorize Vet Labs and Chemdex to enter into this Agreement to
undertake its duties hereunder have been duly and properly taken. This Agreement
is the legal, valid and binding obligation of Vet Labs and Chemdex, enforceable
in accordance with its terms.

b. The execution and delivery of this Agreement by Vet Labs and Chemdex and the
performance of its obligations hereunder will not contravene or conflict with
any law, order, rule or regulation presently in effect and will not conflict
with or result in a breach of any of the terms of provisions of, or constitute a
default under, or result in the creation or imposition of any lien, charge or
encumbrance upon any of the property or assets of Vet Labs pursuant to the terms
of, any agreement or instrument to which Vet Labs is a party or by which it is
bound or to which any of its property or assets are subject. Such performance by
Vet Labs and Chemdex will not violate any provisions of its charter or bylaws.

c. There are no actions, suits, claims, proceedings or investigations pending or
threatened with respect to the business or properties of Vet Labs and Chemdex
which would affect their performance of their obligations under this Agreement.

d. Vet Labs has complied in all material respects with all laws, ordinances,
licensing requirements, regulations and orders applicable to the business being
conducted by it and has filed with the proper authorities all other required
statements, returns and reports.

29. Survival of Representations and Warranties. The statement, representation
and warranties of the parties contained herein and in any exhibit attached
hereto shall be deemed material and to have been relied upon by the parties
hereto, notwithstanding any investigation made by the parties. All such
statements, representations and warranties and the agreements of the parties
contained herein shall continue in effect after execution of this Agreement and
in the formation of the Joint Venture contemplated hereby at the Closing. The
waiver of any misrepresentation or breach of any warranty shall not constitute a
waiver of any other misrepresentation or a breach of warranty hereunder.

Termination and Liquidation.

a. The Joint Venture shall be terminated ten (10) years from the date of this
Agreement, or upon the prior happening of any one of the following events:

(1) The Joint Venture or the last remaining Joint Venturer becomes insolvent or
generally fails to pay, or admits in writing its inability to pay, debts as they
become due, or applies for, consents to or acquiesces in the appointment of a
trustee, receiver, or other custodian for it or any of its property, or makes a
general assignment for the benefit of creditors; or, in the absence of such
application, consent or acquiescence, a trustee, receiver or other custodian is
appointed for it or for a substantial part of its property and is not discharged
within sixty (60) days; or any bankruptcy, reorganization, debt arrangement or
other case or proceeding under any bankruptcy or insolvency law, or any
dissolution or liquidation proceeding, is commenced in respect of the Joint
Venture or the last remaining Joint Venturer, and if such case or proceeding is
not commenced by the Joint Venture or such Joint Venturer, it is consented to or
acquiesced in by the Joint Venture or such Joint Venturer, or remains for sixty
(60) days undismissed; or the Joint Venture or the last remaining Joint Venturer
takes any corporate action to authorize, or in furtherance of, any of the
foregoing; or,

(2) the determination of the Joint Venturers to terminate and liquidate the
Joint Venture; or

(3) the death, withdrawal or cessation to exist as a legal entity of the sole
remaining Joint Venturer; or,



                                      7
<PAGE>   8

(4) the termination of the Joint Venture by operation of law or by judicial
decree.

b. Upon termination of the Joint Venture, the last remaining Joint Venturer (or,
if no Joint Venturer is then remaining, the successor-in-interest of the last
remaining Joint Venturer) shall make full account of the Joint Venture's
property and liabilities, and shall commence to wind up the Joint Venture's
affairs. The Joint Venture's property may be liquidated and its property or the
proceeds thereof shall be applied and distributed, to the extent sufficient, as
follows:

First, all debts and liabilities of the Joint Venture and the expenses of
liquidation shall be paid, except debts and liabilities owed to Joint Venturers
(in their capacities such);

Second, the person required by law to wind up the Joint Venture's affairs shall
set up such reserves as such person may reasonably deem necessary for any
contingent liabilities or obligations of the Joint Venture, provided that any
such reserve shall be paid over by such person to an independent escrow agent,
to be held by the agent or its successors for such period as such person shall
deem advisable for the purpose of applying the reserves to the payment of the
liabilities or obligations, and at the expiration of the period, the balance of
such reserves, if any, shall be distributed as set out in the following clauses;

Third, all debts and liabilities of the Joint Venture owed to the Joint
Venturers or transferees (in their capacities as such) shall be paid.

Fourth, the balance, if any shall be distributed to and among the Joint
Venturers in accordance with the cash distribution percentages as provided
herein.

31. Joint Venture Property. All property, real, personal, or mixed, from time to
time owned by Joint Venturers shall determine that, for convenience, legal title
to any such property shall be held in the name of one or more Joint Venturers;
provided, all Joint Venture property held in the name of one or more Joint
Venturers during the term of the Joint Venture shall be equitable land
beneficially owned by the Joint Venture until termination and such nominee and
trustee of the recorded legal title to such property for the Joint Venture's
sole benefit, subject to the provisions of paragraph--.

32. Binding Effect. This Agreement shall be binding upon and enure to the
benefit of the parties, their respective successors and assigns.

33. Amendment. This Agreement may be modified, amended, changed or canceled, nor
any of its provisions waived, except by instrument in writing signed by all of
the parties or except otherwise specifically agreed herein.

34. Law as to Construction. This Agreement shall be governed by and construed in
accordance with the laws of the State of Kansas.

35. Notices. Any notices or other communication by either party shall be deemed
to have been sufficiently given, for all purposes, if given by being deposited,
postage prepaid, by certified mail, at a post office or letter box addressed as
follows:

a.       To Vet Labs and Chemdex
         Attn: Natu Patel
         1401 Neptune Drive
         Boynton Beach, FL 33426

b.       To Sparhawk


                                      8
<PAGE>   9

         Attn: Bert Hughes
         22 North 6th Street
         Kansas City, KS
         66101

IN WITNESS WHEREOF, the parties above have caused this agreement to be signed
and acknowledged by duly authorized officers on the day and year first above
written.

                                                 CHEMDEX, INC.
                                                 By: /s/ Natu Patel
                                                 Its:

Attest:
CHEMDEX, INC.

BY: /s/ Bascom
Its

                                                 VETERINARY LABORATORIES, INC.
                                                 By: /s/ Natu Patel
                                                 Its:

Attest:
VETERINARY LABORATORIES, INC.
By: /s/ Bascom
Its:

                                                 SPARHAWK LABORATORIES, INC.
                                                 By: /s/ Bert Hughes
                                                 Its:

ATTEST:
SPARHAWK LABORATORIES, INC.
By: /s/ Bascom
Its:

STATE OF MISSOURI  )
                   ) ss.
COUNTY OF PLATTE   )

BE IT REMEMBERED, that on this 1st day of December, 1992 before me, the
undersigned, a Notary Public in and for the County and State aforesaid,
personally appears Natu Patel and , and of CHEMDEX, INC., who are known to me to
be the persons who executed the above and foregoing instrument and acknowledge
the execution of the same on behalf of said corporation.

IN WITNESS WHEREOF, I have hereunto set my hand and affixed by official seal on
the day and year last above written.

Cheryl Bascom
NOTARY PUBLIC




                                      9
<PAGE>   10

CHERYL A. BASCOM
Notary Public-State of Missouri
Commissioned in Platte County
My Commission Expires June 26, 1993

STATE OF MISSOURI  )
                   )ss.

COUNTY OF PLATTE )

BE IT REMEMBERED, that on this 1st day of December, 1992, before me, the
undersigned, a Notary Public in and for the county and State asforesaid,
personally appears Natu Patel and, and of, VETERINARY LABORATORIES, INC., A who
are known to me to be persons who executed the above and foregoing instrument
and acknowledged the execution of the same on behalf of said corporation.

IN WITNESS WHEREOF, I have hereunto set my hand and affixed my official seal on
the day and year last above written.

/s/ Cheryl Bascom
NOTARY PUBLIC

CHERYL  A. BASCOM
Notary Public - State of Missouri
Commissioned in Platte County
My Commission Expires June 26, 1993

STATE OF MISSOURI )
COUNTY OF PLATTE  )

BE IT REMEMBERED, that on this 1st day of December, 1992, before me, the
undersigned, a Notary Public in and for the County and State aforesaid,
personally appears Bert Hughes and, and of SPARHAWK LABORATORIES, INC., who are
known to me to be the persons who executed the above and foregoing instrument
and acknowledged the execution of the same on behalf of said corporation.

IN WITNESS WHEREOF, I have hereunto set my hand and affixed my official seal on
the day and year last above written.

/s/ Cheryl A. Bascom
NOTARY PUBLIC

CHERYL A. BASCOM
Notary Public - State of Missouri
Commissioned in Platte County
My Commission Expires June 26, 1993
natu2

EXHIBIT "A"


                                      10
<PAGE>   11

(Current Assets and Liabilities of Vet Labs)

EXHIBIT "B"
(Capital Contributions)


                                      11