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                                                                     EXHIBIT 4.1

                CERTIFICATE OF DESIGNATION OF RIGHTS, PREFERENCES

                                AND PRIVILEGES OF

                            SERIES A PREFERRED STOCK

                                       OF

                                 PETS.COM, INC.

Pursuant to Section 151 of the General Corporation Law of the State of Delaware:

        I, Julie Wainwright, Chief Executive Officer of Pets.com, Inc., a
corporation organized and existing under the General Corporation Law of the
State of Delaware, in accordance with the provisions of Section 103 thereof, DO
HEREBY CERTIFY:

        That pursuant to the authority conferred upon the Board of Directors by
the Certificate of Incorporation of the said Corporation, the said Board of
Directors on May 27, 2000 adopted the following resolution creating a series of
shares of Preferred Stock designated as Series A Preferred Stock:

        "RESOLVED, that pursuant to the authority vested in the Board of
Directors of the corporation by the Certificate of Incorporation, the Board of
Directors does hereby provide for the issue of a series of Preferred Stock,
$0.00125 par value, of the Corporation, to be designated "Series A Preferred
Stock", initially consisting of One Million, Two Hundred Thousand (1,200,000)
shares and to the extent that the designations, powers, preferences and relative
and other special rights and the qualifications, limitations and restrictions of
the Series A Preferred Stock are not stated and expressed in the Certificate of
Incorporation, does hereby fix and herein state and express such designations,
powers, preferences and relative and other special rights and the
qualifications, limitations and restrictions thereof, as follows (all terms used
herein which are defined in the Certificate of Incorporation shall be deemed to
have the meanings provided therein):

        Section 1. DESIGNATION AND AMOUNT. There is hereby established a series
of Preferred Stock. The shares of such series shall be designated as Series A
Redeemable Preferred Stock (the "Series A Preferred Stock") and the number of
shares constituting the Series A Preferred Stock shall be One Million, Two
Hundred Thousand (1,200,000), none of which have been issued as of the date
hereof. The Series A Preferred Stock shall rank, with respect to the payment of
dividends and the distribution of assets, junior to all series of the
Corporation's Preferred Stock.

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        Section 2. DIVIDENDS AND DISTRIBUTIONS.

               (a) Subject to the rights of the holders of any shares of any
series of Preferred Stock (or any similar stock) ranking prior and superior to
the Series A Preferred Stock with respect to dividends, the holders of shares of
Series A Preferred Stock, in preference to the holders of the common stock of
the Corporation (the "Common Stock"), and to any other junior stock, shall be
entitled to receive, when, as and if declared by the Board of Directors out of
funds legally available for the purpose, quarterly dividends payable in cash on
the first day of March, June, September and December in each year (each such
date being referred to herein as a "Quarterly Dividend Payment Date"),
commencing on the first Quarterly Dividend Payment Date after the first issuance
of a share of Series A Preferred Stock, in an amount per share equal to, subject
to the provision for adjustment hereinafter set forth, the aggregate per share
amount of all cash dividends, and the aggregate per share amount (payable in
kind) of all non-cash dividends or other distributions, other than a dividend
payable in shares of Common Stock or a subdivision of the outstanding shares of
Common Stock (by reclassification or otherwise), declared on the Common Stock
since the immediately preceding Quarterly Dividend Payment Date or, with respect
to the first Quarterly Dividend Payment Date, since the first issuance of any
share of Series A Preferred Stock. In the event the Corporation shall at any
time declare or pay any dividend on the Common Stock payable in shares of Common
Stock, or effect a subdivision or combination or consolidation of the
outstanding shares of Common Stock (by reclassification or otherwise than by
payment of a dividend in shares of Common Stock) into a greater or lesser number
of shares of Common Stock, then in each such case the amount to which holders of
shares of Series A Preferred Stock were entitled immediately prior to such event
under the preceding sentence shall be adjusted by multiplying such amount by a
fraction, the numerator of which is the number of shares of Common Stock
outstanding immediately after such event and the denominator of which is the
number of shares of Common Stock that were outstanding immediately prior to such
event.

               (b) The Corporation shall declare a dividend or distribution on
the Series A Preferred Stock as provided in paragraph (a) of this Section 2
immediately after it declares a dividend or distribution on the Common Stock
(other than a dividend payable in shares of Common Stock).

               (c) Dividends shall begin to accrue and be cumulative on
outstanding shares of Series A Preferred Stock from the Quarterly Dividend
Payment Date next preceding the date of issue of such shares, unless the date of
issue of such shares is prior to the record date for the first Quarterly
Dividend Payment Date, in which case dividends on such shares shall begin to
accrue from the date of issue of such shares, or unless the date of issue is a
Quarterly Dividend Payment Date or is a date after the record date for the
determination of holders of shares of Series A Preferred Stock entitled to
receive a quarterly dividend and before such Quarterly Dividend Payment Date, in
either of which events such dividends shall begin to accrue and be cumulative
from such Quarterly Dividend Payment Date. Accrued but unpaid dividends shall
not bear interest. Dividends paid on the shares of Series A Preferred Stock in
an amount less than the total amount of such dividends at the time accrued and
payable on such shares shall be allocated pro rata on a share-by-share basis
among all such shares at the time outstanding. The Board of

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Directors may fix a record date for the determination of holders of shares of
Series A Preferred Stock entitled to receive payment of a dividend or
distribution declared thereon, which record date shall be not more than 60 days
prior to the date fixed for the payment thereof.

        Section 3. VOTING RIGHTS. Except as may be otherwise required by law,
holders of shares of Series A Preferred Stock shall have no voting rights.

        Section 4. CERTAIN RESTRICTIONS.

               (a) Whenever quarterly dividends or other dividends or
distributions payable on the Series A Preferred Stock as provided in Section 2
are in arrears, thereafter and until all accrued and unpaid dividends and
distributions, whether or not declared, on shares of Series A Preferred Stock
outstanding shall have been paid in full, the Corporation shall not:

                      (i) declare or pay dividends, or make any other
               distributions, on any shares of stock ranking junior (either as
               to dividends or upon liquidation, dissolution or winding up) to
               the Series A Preferred Stock;

                      (ii) declare or pay dividends, or make any other
               distributions, on any shares of stock ranking on a parity (either
               as to dividends or upon liquidation, dissolution or winding up)
               with the Series A Preferred Stock, except dividends paid ratably
               on the Series A Preferred Stock and all such parity stock on
               which dividends are payable or in arrears in proportion to the
               total amounts to which the holders of all such shares are then
               entitled;

                      (iii) redeem or purchase or otherwise acquire for
               consideration shares of any stock ranking junior (either as to
               dividends or upon liquidation, dissolution or winding up) to the
               Series A Preferred Stock, provided that the Corporation may at
               any time redeem, purchase or otherwise acquire shares of any such
               junior stock (i) in exchange for shares of any stock of the
               Corporation ranking junior (either as to dividends or upon
               dissolution, liquidation or winding up) to the Series A Preferred
               Stock or (ii) from employees, consultants or directors of the
               Corporation in connection with the termination of their employee
               or consulting relationship with the Corporation ; or

                      (iv) except as permitted herein, redeem or purchase or
               otherwise acquire for consideration any shares of Series A
               Preferred Stock, or any shares of stock ranking on a parity with
               the Series A Preferred Stock, except in accordance with a
               purchase offer made in writing or by publication (as determined
               by the Board of Directors) to all holders of such shares upon
               such terms as the Board of Directors, after consideration of the
               respective annual dividend rates and other relative rights and
               preferences of the respective series and classes, shall determine
               in good faith will result in fair and equitable treatment among
               the respective series or classes.

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               (b) The Corporation shall not permit any subsidiary of the
Corporation to purchase or otherwise acquire for consideration any shares of
stock of the Corporation unless the Corporation could, under paragraph (a) of
this Section 4, purchase or otherwise acquire such shares at such time and in
such manner.

        Section 5. REACQUIRED SHARES. Any shares of Series A Preferred Stock
purchased or otherwise acquired by the Corporation in any manner whatsoever
shall be retired and cancelled promptly after the acquisition thereof. All such
shares shall upon their cancellation become authorized but unissued shares of
Preferred Stock and may be reissued as part of a new series of Preferred Stock
subject to the conditions and restrictions on issuance set forth herein, in the
Certificate of Incorporation, or in any other certificates of designation or
articles of amendment thereto creating a series of Preferred Stock or any
similar stock or as otherwise required by law.

        Section 6. LIQUIDATION, DISSOLUTION OR WINDING UP. Upon any liquidation,
dissolution or winding up of the Corporation, no distribution shall be made (1)
to the holders of shares of stock ranking junior (either as to dividends or upon
liquidation, dissolution or winding up) to the Series A Preferred Stock unless,
prior thereto, the holders of shares of Series A Preferred Stock shall have
received $0.00125 per share, plus an amount equal to accrued and unpaid
dividends and distributions thereon, whether or not declared, to the date of
such payment, provided that the holders of shares of Series A Preferred Stock
shall thereafter be entitled to receive an aggregate amount per share, subject
to the provision for adjustment hereinafter set forth, equal to the aggregate
amount to be distributed upon liquidation to holders of shares of Common Stock,
or (2) to the holders of shares of stock ranking on a parity (either as to
dividends or upon liquidation, dissolution or winding up) with the Series A
Preferred Stock, except distributions made ratably on the Series A Preferred
Stock and all such parity stock in proportion to the total amounts to which the
holders of all such shares are entitled upon such liquidation, dissolution or
winding up. In the event the Corporation shall at any time declare or pay any
dividend on the Common Stock payable in shares of Common Stock, or effect a
subdivision or combination or consolidation of the outstanding shares of Common
Stock (by reclassification or otherwise than by payment of a dividend in shares
of Common Stock) into a greater or lesser number of shares of Common Stock, then
in each such case the aggregate amount to which holders of shares of Series A
Preferred Stock were entitled immediately prior to such event under the proviso
in clause (1) of the preceding sentence shall be adjusted by multiplying such
amount by a fraction the numerator of which is the number of shares of Common
Stock outstanding immediately after such event and the denominator of which is
the number of shares of Common Stock that were outstanding immediately prior to
such event.

        Section 7. CONSOLIDATION, MERGER, ETC. In case the Corporation shall
enter into any consolidation, merger, combination or other transaction in which
the shares of Common Stock are exchanged for or changed into other stock or
securities, cash and/or any other property, then in any such case each share of
Series A Preferred Stock shall at the same time be similarly exchanged or
changed into an amount per share, subject to the provision for adjustment
hereinafter set forth, equal the aggregate amount of stock, securities, cash
and/or any other property (payable in kind), as the case may be, into which or
for which each share of Common Stock is changed or exchanged (subject to
applicable NASD regulations regarding shareholder

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approval). In the event the Corporation shall at any time declare or pay any
dividend on the Common Stock payable in shares of Common Stock, or effect a
subdivision or combination or consolidation of the outstanding shares of Common
Stock (by reclassification or otherwise than by payment of a dividend in shares
of Common Stock) into a greater or lesser number of shares of Common Stock, then
in each such case the amount set forth in the preceding sentence with respect to
the exchange or change of shares of Series A Preferred Stock shall be adjusted
by multiplying such amount by a fraction, the numerator of which is the number
of shares of Common Stock outstanding immediately after such event and the
denominator of which is the number of shares of Common Stock that were
outstanding immediately prior to such event.

        Section 8. CONVERSION. The Series A Preferred Stock shall be subject to
conversion as follows:

               (a) AUTOMATIC CONVERSION. Each share of Series A Preferred Stock
shall automatically be converted into one share of Common Stock ("Conversion
Ratio") on the date that Stockholder Approval is obtained.

               (b) MECHANICS OF AUTOMATIC CONVERSION. All holders of record of
shares of Series A Preferred Stock will be given written notice of the actual
date of such conversion within ten days thereafter. Notice will be sent by mail,
first class, postage prepaid, to each record holder of Series A Preferred Stock
at such holder's address appearing on the stock register. Each holder of shares
of Series A Preferred Stock shall surrender his or its certificate or
certificates for all such shares to the Corporation at the place designated in
such notice, and shall thereafter receive certificates for the number of shares
of Common Stock or other securities to which such holder is entitled. On the
date of conversion, all rights with respect to the Series A Preferred Stock will
terminate, except only (1) any rights to receive declared but unpaid dividends
with a record date preceding the date of conversion, and (2) the rights of the
holders thereof, upon surrender of their certificate or certificates therefor,
to receive certificates for the number of shares of Common Stock or other
securities into which such Series A Preferred Stock has been converted and cash
for fractional shares. If so required by the Corporation, certificates
surrendered for conversion shall be endorsed or accompanied by written
instrument or instruments of transfer, in form satisfactory to the Corporation,
duly executed by the registered holder or by his or its attorney duly authorized
in writing. All certificates evidencing shares of Series A Preferred Stock which
are required to be surrendered for conversion in accordance with the provisions
hereof shall, from and after the date such certificates are so required to be
surrendered, be deemed to have been retired and cancelled and the shares of
Series A Preferred Stock represented thereby converted into Common Stock for all
purposes, notwithstanding the failure of the holder or holders thereof to
surrender such certificates on or prior to such date. As soon as practicable
after the conversion date and the surrender of the certificate or certificates
for Series A Preferred Stock as aforesaid, the Corporation shall cause to be
issued and delivered to such holder, or to his or its written order, a
certificate or certificates for the number of full shares of Common Stock or
other securities issuable on such conversion in accordance with the provisions
hereof.

               (c) ADJUSTMENTS FOR STOCK SPLITS, STOCK DIVIDENDS AND
COMBINATIONS OF COMMON STOCK. In the event the outstanding shares of Common
Stock shall after the date of

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this Certificate of Determination be further subdivided (split), or combined
(reverse split), by reclassification or otherwise, or in the event of any
dividend or other distribution payable on the Common Stock in shares of Common
Stock, the Conversion Ratio in effect immediately prior to such subdivision,
combination, dividend or other distribution shall, concurrently with the
effectiveness of such subdivision, combination, dividend or other distribution,
be proportionately adjusted.

               (d) STOCKHOLDER APPROVAL. For the purposes of this Section 8
"Stockholder Approval" means approval by the Stockholders of the Corporation of
the conversion of the Series A Preferred Stock into Common Stock at the
Conversion Ratio specified above at a duly-called meeting of the stockholders
and the day, if any, upon which the Corporation determines, in good faith and
based upon the written concurrence of the principal securities exchange or
quotation system upon which the Corporation's Common Stock is then traded, that
stockholder approval is not required for such conversion in order for the
Corporation to be in compliance with the rules of such exchange or system
regarding stockholder approval.

        Section 9. REDEMPTION.

               (a) Subject to the rights of series of Preferred Stock which may
from time to time come into existence, at any date after September 30, 2001, the
Corporation shall redeem, on the date which is forty-five (45) days (such day
being the "Redemption Date") after receipt by the Corporation of a written
request from the holders at least a majority of the then outstanding Series A
Preferred Stock that all or some of such holders shares be redeemed, the shares
specified in such request by paying in cash therefor a sum per share equal to
the greater of (i) $2.0969 per share and (ii) the closing price of the
Corporation's Common Stock on a securities exchange or the Nasdaq Stock Market
on the date on which the Corporation received written notice pursuant to this
subsection 9(a), if applicable, plus with respect to (i) and (ii) all declared
or accumulated but unpaid dividends on such shares (the "Series A Redemption
Price").

               (b) As used herein and in subsections (9)(c) and (d) below, the
term "Redemption Date" shall refer to each "Series A Redemption Date" and the
term "Redemption Price" shall refer to each "Series A Redemption Price." At
least five (5) days prior to each Redemption Date, written notice shall be
mailed, first class postage prepaid, to each holder of record (at the close of
business on the business day next preceding the day on which notice is given) of
the Series A Preferred Stock to be redeemed, at the address last shown on the
records of the Corporation for such holder, notifying such holder of the
redemption to be effected, specifying the number of shares to be redeemed from
such holder, the Redemption Date, the Redemption Price, the place at which
payment may be obtained and calling upon such holder to surrender to the
Corporation, in the manner and at the place designated, his, her or its
certificate or certificates representing the shares to be redeemed (the
"Redemption Notice"). Except as provided in subsection (9)(c), on or after the
Redemption Date, each holder of Series A Preferred Stock to be redeemed shall
surrender to the Corporation the certificate or certificates representing such
shares, in the manner and at the place designated in the Redemption Notice, and
thereupon the Redemption Price of such shares shall be paid to the order of the
person whose name appears on such certificate or certificates as the owner
thereof and each surrendered certificate shall be

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cancelled. In the event less than all the shares represented by any such
certificate are redeemed, a new certificate shall be issued representing the
unredeemed shares.

               (c) From and after the Redemption Date, unless there shall have
been a default in payment of the Redemption Price, all rights of the holders of
shares of Series A Preferred Stock designated for redemption in the Redemption
Notice as holders of Series A Preferred Stock (except the right to receive the
Redemption Price without interest upon surrender of their certificate or
certificates) shall cease with respect to such shares, and such shares shall not
thereafter be transferred on the books of the Corporation or be deemed to be
outstanding for any purpose whatsoever. If the funds of the Corporation legally
available for redemption of shares of Series A Preferred Stock on any Redemption
Date are insufficient to redeem the total number of shares of Series A Preferred
Stock to be redeemed on such Redemption Date, those funds which are legally
available will be used to redeem the maximum possible number of such shares
ratably among the holders of such shares to be redeemed based upon their
holdings of Series A Preferred Stock. The shares of Series A Preferred Stock not
redeemed shall remain outstanding and entitled to all the rights and preferences
provided herein.

               (d) Prior to each Redemption Date, the Corporation shall deposit
the Redemption Price of all shares of Series A Preferred Stock designated for
redemption in the Redemption Notice and not yet redeemed or converted, with a
bank or trust corporation having aggregate capital and surplus in excess of
$100,000,000 as a trust fund for the benefit of the respective holders of the
shares designated for redemption and not yet redeemed, with irrevocable
instructions and authority to the bank or trust corporation to public the notice
of redemption thereof and pay the Redemption Price for such shares to their
respective holders on or after the Redemption Date, upon receipt of notification
from the Corporation that such holder has surrendered his, her or its share
certificate to the Corporation pursuant to subsection (9)(b) above. As of the
date of any such deposit (even if prior to the Redemption Date), the deposit
shall constitute full payment of the shares to the holders, and from and after
the date of the deposit the shares so called for redemption shall be redeemed
and shall be deemed to be no longer outstanding, and the holders thereof shall
cease to be shareholders with respect to such shares and shall have no rights
with respect thereto except the rights to receive from the bank or trust
corporation payment of the Redemption Price of the shares, without interest,
upon surrender of their certificates therefor. The balance of any monies
deposited by the Corporation pursuant to this subsection (9)(d) remaining
unclaimed at the expiration of one (1) year following the Redemption Date shall
thereafter be returned to the Corporation upon its request expressed in a
resolution of its Board of Directors.

        Section 10. MISCELLANEOUS.

               (a) RESERVATION OF STOCK ISSUABLE UPON CONVERSION.

                      (i) The Corporation shall at all times reserve and keep
               available out of its authorized but unissued shares of Common
               Stock, solely for the purpose of effecting the conversion of the
               shares of the Series A Preferred Stock, such number of its shares
               of Common Stock as shall from time to time be sufficient to

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               effect the conversion of all outstanding shares of the Series A
               Preferred Stock; and if at any time the number of authorized but
               unissued shares of Common Stock shall not be sufficient to effect
               the conversion of all then outstanding shares of the Series A
               Preferred Stock, in addition to such other remedies as shall be
               available to the holder of such Preferred Stock, the Corporation
               will use its best efforts to take such corporate action as may,
               in the opinion of its counsel, be necessary to increase its
               authorized but unissued shares of Common Stock to such number of
               shares as shall be sufficient for such purposes, including,
               without limitation, engaging in best efforts to obtain the
               requisite shareholder approval of any necessary amendment to its
               Certificate of Incorporation.

                      (ii) If any shares of Common Stock required to be reserved
               for purposes of conversion of the Series A Preferred Stock
               hereunder require registration with or approval of any
               governmental authority under any Federal or state law before such
               shares may be issued upon conversion, the Corporation shall in
               good faith and as expeditiously as possible endeavor to cause
               such shares to be duly registered or approved, as the case may
               be. The Corporation will seek to list the shares of Common Stock
               required to be delivered upon conversion of the Series A
               Preferred Stock, prior to the delivery, upon each national
               securities exchange or national quotation system, if any, upon
               which the outstanding shares of Common Stock are listed at the
               time of delivery.

               (b) TAXES. The Corporation will pay any documentary stamp of
similar issue or transfer taxes payable in respect of the issue or delivery of
shares of Common Stock on conversion of Series A Preferred Stock; provided,
however, that the Corporation will not be required to pay any tax which may be
payable in respect of any transfer involved in the issue or delivery of shares
of Common Stock in a name other than that of the holder of record of the Series
A Preferred Stock to be converted and no such issue or delivery will be made
unless and until the person requesting the issue or delivery has paid to the
Corporation the amount of any such tax or has established, to the satisfaction
of the Corporation, that the tax has been paid.

               (c) NOTICES. Any notice required by the provisions of this
Section 10 to be given to the holders of shares of Series A Preferred Stock
shall be deemed given if deposited in the United States mail, postage prepaid,
and addressed to each holder of record at such holder's address appearing on the
books of the Corporation."

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        IN WITNESS WHEREOF, I have executed and subscribed this Certificate and
do affirm the foregoing as true under the penalties of perjury this 8th day of
June, 2000.

                                         /s/  Julie Wainwright
                                        ----------------------------------------
                                        Julie Wainwright,
                                        Chief Executive Officer

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                                                                     EXHIBIT 4.2

                               AMENDMENT NO. 1 TO
                      AMENDED AND RESTATED RIGHTS AGREEMENT

        This Amendment No. 1 dated July 13, 2000 (this "Amendment") to the
Amended and Restated Rights Agreement dated as of January 18, 2000 (the "Rights
Agreement"), between Pets.com, Inc. a Delaware corporation (the "Company") and
the individuals and entities set forth on Exhibit A attached to the Rights
Agreement (the "Prior Rights Holders"), is by and among the Company, Prior
Rights Holders who hold such number of shares of Registrable Securities (as
defined in the Rights Agreement) to have sufficient authority to amend the
Rights Agreement pursuant to Section 5.2 thereof, and the transferee of
Discovery.com, Inc. ("New Investor").

        WHEREAS, the Company and the Prior Rights Holders entered into the
Rights Agreement, pursuant to which the Company granted registration rights,
information rights and other rights to the Prior Rights Holders;

        WHEREAS, New Investor may acquire shares ("Shares") of the Company's
Common Stock and/or Series A Preferred Stock;

        WHEREAS, the Company has agreed that if and when New Investor shall
acquire Shares of the Company, the Company shall grant to New Investor piggyback
registration rights in connection with 1,430,700 of the Shares (as such number
may be increased, decreased or otherwise adjusted in the event of a
recapitalization or similar event with respect to the Company's capital
structure);

        WHEREAS, the 1,430,700 Shares that are eligible to receive piggyback
registration rights hereunder shall include both Common Stock issued or
transferred to New Investor as well as Common Stock issuable upon conversion of
shares of Series A Preferred Stock issued or transferred to New Investor
(collectively, the "New Investor Shares"); and

        WHEREAS, the Company intends to fulfill the foregoing obligation by
amending the Rights Agreement to add the New Investor Shares to the definition
of "Registrable Securities," except for the purposes of Sections 2, 3, and 4 of
the Rights Agreement, and to modify the definition of "Holder" with respect to
New Investor as set forth below;

        NOW, THEREFORE, the parties hereto agree as follows:

        1. Definitions. Unless specifically designated otherwise, capitalized
terms used herein shall have the same meanings given them in the Agreement.

        2. New Investor. The Rights Agreement is hereby amended to add New
Investor as a party to the Agreement. By execution of this Amendment, New
Investor agrees that it shall be subject to the terms and conditions contained
in the Agreement in exchange for the applicable rights granted thereunder, as
amended by this Amendment.

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        3. Registrable Securities. Section 1.1(b) is hereby amended and restated
to read in its entirety:

                      "(b) The term "Registrable Securities" means (i) the
               shares of Common Stock issuable or issued upon conversion of the
               Series A Preferred Stock, Series B Preferred Stock and Series C
               Preferred Stock, (ii) the shares of Common Stock issued to the
               Founder (the "Founder's Stock"), provided, however, that for the
               purposes of Sections 1.2, 1.4, 1.13, 3 and 5.2 the Founder's
               Stock shall not be deemed Registrable Securities and the Founder
               shall not be deemed a Holder, (iii) up to 1,430,700 New Investor
               Shares (as such number may be increased, decreased or otherwise
               adjusted in the event of a recapitalization or similar event with
               respect to the Company's capital structure) held by a transferee
               of Discovery.com, Inc., provided, however, that for the purposes
               of Sections 2, 3 and 4 such New Investor Shares shall not be
               deemed Registrable Securities and New Investor shall not be
               deemed a Holder, (iv) any other shares of Common Stock of the
               Company issued as (or issuable upon the conversion or exercise of
               any warrant, right or other security which is issued as) a
               dividend or other distribution with respect to, or in exchange
               for or in replacement of, the shares listed in (i), (ii) and
               (iii); provided, however, that the foregoing definition shall
               exclude in all cases any Registrable Securities sold by a person
               in a transaction in which his or her rights under this Agreement
               are not assigned. Notwithstanding the foregoing, Common Stock or
               other securities shall only be treated as Registrable Securities
               if and so long as they have not been (A) sold to or through a
               broker or dealer or underwriter in a public distribution or a
               public securities transaction, or (B) sold in a transaction
               exempt from the registration and prospectus delivery requirements
               of the Securities Act under Section 4(1) thereof so that all
               transfer restrictions, and restrictive legends with respect
               thereto, if any, are removed upon the consummation of such sale;"

        4. Holder. Section 1.1(d) is hereby amended and restated to read in its
entirety:

                      "(d) The term "Holder" means any person owning or having
               the right to acquire Registrable Securities or any assignee
               thereof in accordance with Section 1.12 of this Agreement;
               provided, however, that the Founder shall not be deemed to be a
               Holder with respect to Founder's Stock only for purposes of
               Sections 1.2, 1.4 and 1.13, nor an Eligible Holder (as defined
               herein below in Section 2.1) with respect to Founder's Stock only
               for purposes of Section 3.2; and provided further, that New
               Investor shall not be deemed to be a Holder with respect to: (i)
               Sections 2, 3 and 4 herein; (ii) the right granted to certain
               Holders in the first sentence of Section.1.2(a) to submit a
               written request or requests that the Company file a registration
               statement under the Securities Act covering the

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               registration of Registrable Securities; and (iii) the right
               granted to certain Holders in the first sentence of Section 1.4
               to submit a written request or requests that the Company effect a
               registration on Form S-3;"

        5. Effect of Amendment. As of the date of this Amendment each reference
in the Rights Agreement to:

               (a) "Registrable Securities" shall include up to 1,430,700 New
Investor Shares (as such number may be increased, decreased or otherwise
adjusted in the event of a recapitalization or similar event with respect to the
Company's capital structure), except for purposes of Sections 2, 3 and 4 of the
Rights Agreement, for which the New Investor Shares shall not be considered
"Registrable Securities"; and

               (b) "Rights Holders" or "Holders" shall include New Investor,
except for purposes of: (i) Sections 2, 3 and 4 of the Rights Agreement; (ii)
the right granted to certain Holders in the first sentence of Section.1.2(a) to
submit a written request or requests that the Company file a registration
statement under the Securities Act covering the registration of Registrable
Securities; and (iii) the right granted to certain Holders in the first sentence
of Section 1.4 to submit a written request or requests that the Company effect a
registration on Form S-3; for each of which New Investor shall not be considered
a "Holder" or an "Eligible Holder."

Except as specifically set forth herein, the terms and conditions contained in
the Rights Agreement shall continue in full force and effect.

        6.     Miscellaneous.

               6.1 Third Parties. Nothing in this Amendment, express or implied,
is intended to confer upon any party, other than the parties hereto, and their
respective successors and assigns, any rights, remedies, obligations or
liabilities under or by reason of this Amendment, except as expressly provided
herein.

               6.2 Governing Law. This Amendment shall be governed by and
construed under the laws of the State of California, without reference to
conflicts of laws principles.

               6.3 Counterparts. This Amendment may be executed in one or more
counterparts, each of which shall be deemed an original, but all of which
together shall constitute one and the same instrument.

               6.4 Severability. If one or more provisions of this Amendment are
held to be unenforceable under applicable law, portions of such provisions, or
such provisions in their entirety, to the extent necessary, shall be severed
from this Amendment, and the balance of this Amendment shall be enforceable in
accordance with its terms.

                             SIGNATURE PAGES FOLLOW

                                      -3-
<PAGE>   4

               IN WITNESS WHEREOF, the parties have executed this Amendment as
of the date first above written.

                                        COMPANY:

                                        PETS.COM, INC.
                                        a Delaware corporation

                                        By:   /s/  Paul Manca
                                           -------------------------------------

                                        Name:      Paul Manca
                                             -----------------------------------

                                        Title:     Chief Financial Officer
                                              ----------------------------------

                                        Dated:
                                             -----------------------------------

                                        "PRIOR RIGHTS HOLDERS"

                                        By:   /s/  Greg McLemore
                                           -------------------------------------

                                        Its:
                                            ------------------------------------

                                        Name:      Greg McLemore
                                             -----------------------------------

                                        Address:   Web Magic, Inc.
                                                --------------------------------
                                                   87 N. Raymond Ave., Suite 850
                                        ----------------------------------------
                                                   Pasadena, CA  91103
                                        ----------------------------------------

<PAGE>   5

                                       "PRIOR RIGHTS HOLDERS"

                                       By: /s/  Mark Britto
                                          --------------------------------------

                                       Its:     Vice President, Amazon.com, Inc.
                                           -------------------------------------

                                       Name:    Mark Britto
                                            ------------------------------------

                                       Address: Amazon.com, Inc.
                                               ---------------------------------
                                                1200 12th Ave. South, Suite 1200
                                       -----------------------------------------
                                                Seattle, WA  91844
                                       -----------------------------------------

                                       "PRIOR RIGHTS HOLDERS"

                                       By:   /s/  [Signature Illegible]
                                          --------------------------------------

                                       Its:       Managing Member
                                           -------------------------------------

                                       Name:      Hummer Winblad Technology
                                                  Fund III, L.P.
                                            ------------------------------------

                                       Address:   2 South Park
                                               ---------------------------------
                                                  San Francisco, CA  94107
                                       -----------------------------------------

                                       -----------------------------------------

                                       "PRIOR RIGHTS HOLDERS"

                                       By:   /s/  [Signature Illegible]
                                          --------------------------------------

                                       Its:       Managing Member
                                           -------------------------------------

                                       Name:      Hummer Winblad Venture
                                                  Partners III, L.P.
                                            ------------------------------------

                                       Address:   2 South Park
                                               ---------------------------------
                                                  San Francisco, CA  94107
                                       -----------------------------------------

                                       -----------------------------------------

                                      -5-
<PAGE>   6

                                       "PRIOR RIGHTS HOLDERS"

                                       By:   /s/  [Signature Illegible]
                                          --------------------------------------

                                       Its:       Managing Member
                                           -------------------------------------

                                       Name:      Hummer Winblad Technology Fund
                                                  IV, L.P.
                                            ------------------------------------

                                       Address:   2 South Park
                                               ---------------------------------
                                                  San Francisco, CA  94107
                                       -----------------------------------------

                                       -----------------------------------------

                                       "PRIOR RIGHTS HOLDERS"

                                       By:   /s/  [Signature Illegible]
                                          --------------------------------------

                                       Its:       Managing Member
                                           -------------------------------------

                                       Name:      Hummer Winblad Venture
                                                  Partners IV, L.P.
                                            ------------------------------------

                                       Address:   2 South Park
                                               ---------------------------------
                                                  San Francisco, CA  94107
                                       -----------------------------------------

                                       -----------------------------------------

                                       "PRIOR RIGHTS HOLDERS"

                                       By:   /s/  Eric Moore
                                          --------------------------------------

                                       Its:       Controller
                                           -------------------------------------

                                       Name:      Eric Moore
                                            ------------------------------------

                                       Address:   1875 S. Grant St., Suite 600
                                               ---------------------------------
                                                  San Mateo, CA  94402
                                       -----------------------------------------
                                                  Pasadena, CA  91103
                                       -----------------------------------------
                                       FBO:  BOWMAN CAPITAL CLIPPER FUND, L.P.,
                                       FORMERLY KNOWN AS THE SPINNAKER CLIPPER
                                       FUND, L.P.

                                      -6-
<PAGE>   7

                                       "PRIOR RIGHTS HOLDERS"

                                       By:   /s/  Eric Moore
                                          --------------------------------------

                                       Its:       Controller
                                           -------------------------------------

                                       Name:      Eric Moore
                                            ------------------------------------

                                       Address:   1875 S. Grant St., Suite 600
                                               ---------------------------------
                                                  San Mateo, CA  94402
                                       -----------------------------------------
                                                  Pasadena, CA  91103
                                       -----------------------------------------
                                       FBO:  BOWMAN CAPITAL TECHNOLOGY FUND,
                                       L.P., FORMERLY KNOWN AS THE SPINNAKER
                                       TECHNOLOGY FUND, L.P.

                                       "PRIOR RIGHTS HOLDERS"

                                       By:   /s/  Eric Moore
                                          --------------------------------------

                                       Its:       Controller
                                           -------------------------------------

                                       Name:      Eric Moore
                                            ------------------------------------

                                       Address:   1875 S. Grant St., Suite 600
                                               ---------------------------------
                                                  San Mateo, CA  94402
                                       -----------------------------------------
                                                  Pasadena, CA  91103
                                       -----------------------------------------
                                       FBO:  BOWMAN CAPITAL TECHNOLOGY OFFSHORE
                                       FUND, LIMITED, FORMERLY KNOWN AS THE
                                       SPINNAKER TECHNOLOGY OFFSHORE FUND,
                                       LIMITED.

                                      -7-
<PAGE>   8

                                       "PRIOR RIGHTS HOLDERS"

                                       By:   /s/  Eric Moore
                                          --------------------------------------

                                       Its:       Controller
                                           -------------------------------------

                                       Name:      Eric Moore
                                            ------------------------------------

                                       Address:   1875 S. Grant St., Suite 600
                                               ---------------------------------
                                                  San Mateo, CA  94402
                                       -----------------------------------------
                                                  Pasadena, CA  91103
                                       -----------------------------------------
                                       FBO:  BOWMAN CAPITAL FOUNDERS FUND, L.P.,
                                       FORMERLY KNOWN AS THE SPINNAKER FOUNDERS
                                       FUND, L.P.

                                       "PRIOR RIGHTS HOLDERS"

                                       By:   /s/  Eric Moore
                                          --------------------------------------

                                       Its:       Controller
                                           -------------------------------------

                                       Name:      Eric Moore
                                            ------------------------------------

                                       Address:   1875 S. Grant St., Suite 600
                                               ---------------------------------
                                                  San Mateo, CA  94402
                                       -----------------------------------------
                                                  Pasadena, CA  91103
                                       -----------------------------------------
                                       FBO: BOWMAN CAPITAL FOUNDERS OFFSHORE
                                       FUND CAYMAN LIMITED, FORMERLY KNOWN AS
                                       THE SPINNAKER OFFSHORE FOUNDERS FUND
                                       CAYMAN LIMITED.

                                      -8-
<PAGE>   9

                                       CATALYST INVESTMENTS, LLC
                                       BY:  THE WALT DISNEY COMPANY, ITS SOLE
                                       MEMBER

                                       By:   /s/  Suet Lai
                                          --------------------------------------

                                       Its:       Vice President, Counsel
                                           -------------------------------------

                                       Name:      Suet Lai
                                            ------------------------------------

                                       Address:   500 South Buena Vista St.
                                               ---------------------------------
                                                  Burbank, CA  91521
                                       -----------------------------------------
                                                  Attn:  General Counsel
                                       -----------------------------------------

                                      -9-
<PAGE>   10

                                       "NEW INVESTOR"

                                       ENTITY:

                                       By:
                                          --------------------------------------

                                       Name:
                                            ------------------------------------

                                       Title:
                                             -----------------------------------

                                       Address:
                                               ---------------------------------

                                       -----------------------------------------

                                       -----------------------------------------

                                      -10-

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