RIGHTS AGREEMENT AMENDMENT

     Rights Agreement Amendment, dated as of March 30, 2000 (this "Amendment"),
to the Rights Agreement dated as of December 30, 1997 (the "Rights Agreement"),
between Veterinary Centers of America, Inc., a Delaware corporation (the
"Company") and Continental Stock Transfer & Trust Corporation, as Rights Agent
(the "Rights Agent").

A.   The Company and the Rights Agent have heretofore executed and delivered the
     Rights Agreement. Pursuant to Section 28 of the Rights Agreement, the
     Company and the Rights Agent may from time to time supplement or amend the
     Rights Agreement in accordance with the provisions of Section 28 thereof.

     In consideration of the foregoing premises and mutual agreements set forth
in the Rights Agreement and this Amendment, the parties hereto agree as follows:

     1.   The definition of "Acquiring Person" in Section 1 of the Rights
          Agreement is hereby amended and restated to read in its entirety as
          follows:

     "Acquiring Person" shall mean (i) any Person (as hereinafter defined) who
is an Adverse Person (as hereinafter defined), or (ii) any Person who or which,
together with all Affiliates (as hereinafter defined) and Associates (as
hereinafter defined) of such Person, shall, subsequent to the Declaration Date,
become the Beneficial Owner (as hereinafter defined) of 15% or more of the
shares of Common Stock then outstanding, but shall not include (x) any Exempt
Person (as hereinafter defined), (y) any Permitted Holder, or (z) any Person who
becomes a Beneficial Owner of 15% or more of the shares of Common Stock then
outstanding solely because (1) of a change in the aggregate number of shares of
Common Stock outstanding since the last date on which such Person acquired
Beneficial Ownership of any shares of Common Stock, or (2) it acquired such
Beneficial Ownership in the good faith belief that such acquisition would not
(A) cause such Beneficial Ownership to equal or exceed 15% of the shares of
Common Stock then outstanding (or in the case of a Permitted Holder, the
percentage the Permitted Holder may hold without ceasing to be a Permitted
Holder) and such Person relied in good faith in computing the percentage of its
Beneficial Ownership on publicly filed reports or documents of the Company which
are inaccurate or out-of-date, or (B) otherwise cause a Distribution Date or the
adjustment provided for in Section 14 to occur. Notwithstanding clause (z) of
the prior sentence, if any Person that is not an Acquiring Person because of the
operation of such clause (z) does not reduce its Beneficial Ownership of shares
of Common Stock to less than 15% (or in the case of a Permitted Holder, the
percentage the Permitted Holder may hold without ceasing to be a Permitted
Holder) by the close of business on the fifth Business Day after notice from the
Company (the date of notice being the first day) that such Person's Beneficial
Ownership of Common Stock equals or exceeds 15% (or in the case of a Permitted
Holder, the percentage the Permitted Holder may hold without ceasing to be a
Permitted Holder), such Person shall, at the end of such five Business Day
period, become an Acquiring Person (and clause (z) shall no longer apply to such
Person). For purposes of this definition, the determination whether any Person
acted in "good faith" shall be conclusively determined by the Board of
Directors, acting by a vote of those directors of the Company whose approval
would be required to redeem the Rights under Section 25. Notwithstanding
anything in this Rights Agreement, no party to the Merger Agreement (as defined
below) nor any officer, director stockholder or partner of any party to the
Merger Agreement or their respective Affiliates or Associates, or any other
Person, shall become an "Acquiring Person" as the result of entering into,


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performing the terms of, or consummating the transactions contemplated by (x)
the Agreement and Plan of Merger, dated on or about March 30, 2000, as amended
from time to time (the "Merger Agreement"), among the Company, Vicar Operating,
Inc., a Delaware corporation and VICAR Recap, Inc., a Delaware corporation
("Recap") wholly owned by Green Equity Investors III, L.P. ("Parent") or (y) any
other agreement entered into in connection with the Merger Agreement
(collectively, the "Ancillary Agreements")."

     2.   Section 3(a) of the Rights Agreement is amended by adding a new
          sentence as the final sentence thereto, which shall read in its
          entirety as follows:

     "Notwithstanding anything in this Rights Agreement to the contrary, a
Distribution Date shall not be deemed to have occurred solely as a result of (i)
the approval, execution or delivery of the Merger Agreement or the Ancillary
Agreements, or (ii) the consummation of the Merger (as defined in the Merger
Agreement) or the performance of the terms of the Merger Agreement or the
Ancillary Agreements."

     3.   This Amendment shall be governed by and construed in accordance with
          the laws of the State of Delaware.

     4.   This Amendment may be executed in any number of counterparts and each
          of such counterparts shall for all purposes be deemed an original, and
          all such counterparts shall together constitute but one and the same
          instrument.

     5.   Except as expressly set forth herein, this Amendment shall not by
          implication or otherwise alter, modify, amend or in any way affect any
          of the terms, conditions, obligations, covenants or agreements
          contained in the Rights Agreement, all of which are ratified and
          affirmed in all respects and shall continue in full force and effect.


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     IN WITNESS WHEREOF, the parties hereto have caused this Amendment to be
duly executed as of the day and year first above written.



                                          VETERINARY CENTERS OF AMERICA, INC.

                                             /S/ ROBERT L. ANTIN
                                             -----------------------------------
                                             By:     Robert L. Antin
                                             Title:  Chief Executive Officer



                                          CONTINENTAL STOCK TRANSFER & TRUST CO.

                                             /S/ MICHAEL NELSON
                                             -----------------------------------
                                             By:     Michael Nelson
                                             Title:  President