[FACE OF CERTIFICATE] NUMBER U SEE REVERSE FOR CERTAIN DEFINITIONS PET DRX CORPORATION UNITS CONSISTING OF ONE SHARE OF COMMON STOCK AND ONE WARRANT TO PURCHASE ONE SHARE OF COMMON STOCK U N I T S CUSIP ###-###-#### This Certifies that is the owner of ____________ Units.

Exhibit 4.2

[FACE OF CERTIFICATE]

NUMBER

U

SEE REVERSE FOR CERTAIN DEFINITIONS

PET DRX CORPORATION

UNITS CONSISTING OF ONE SHARE OF COMMON STOCK AND ONE WARRANT TO PURCHASE
ONE SHARE OF COMMON STOCK

U N I T S

CUSIP ###-###-####

This Certifies that

is the owner of ____________ Units.

Each Unit (“Unit”) consists of one (1) share of common stock, par value $.0001 per share (“Common Stock”), of Pet DRx Corporation, a Delaware corporation (the “Company”), and one warrant (the “Warrant”). Each Warrant entitles the holder to purchase one (1) share of Common Stock for $6.00 per share (subject to adjustment). Each Warrant will become exercisable on the later of (i) the Company’s completion of a merger, capital stock exchange, asset acquisition or other similar business combination and (ii) March 17, 2007, and will expire unless exercised before 5:00 p.m., New York City Time, on March 17, 2010, or earlier upon redemption (the “Expiration Date”). The Common Stock and Warrants comprising the Units represented by this certificate are not transferable separately prior to ________, 2006, subject to earlier separation in the discretion of Roth Capital Partners, LLC. The terms of the Warrants are governed by a Warrant Agreement, dated as of _______, 2006, between the Company and Corporate Stock Transfer, Inc., as Warrant Agent, and are subject to the terms and provisions contained therein, all of which terms and provisions the holder of this certificate consents to by acceptance hereof. Copies of the Warrant Agreement are on file at the office of the Warrant Agent at 3200 Cherry Creek South Drive, Suite 430, Denver, Colorado 80209 and are available to any Warrant holder on written request and without cost.

This certificate is not valid unless countersigned by the Transfer Agent and Registrar of the Company.

Witness the facsimile seal of the Company and the facsimile signature of its duly authorized officers.

By

SECRETARY

[SEAL]

PRESIDENT

COUNTERSIGNED AND REGISTERED:

CORPORATE STOCK TRANSFER, INC.

TRANSFER AGENT AND REGISTRAR

BY

AUTHORIZED SIGNATURE

[REVERSE OF CERTIFICATE]

Pet DRx Corporation

The Company will furnish without charge to each stockholder who so requests, a statement of the powers, designations, preferences and relative, participating, optional or other special rights of each class of stock or series thereof of the Company and the qualifications, limitations, or restrictions of such preferences and/or rights.

The following abbreviations, when used in the inscription on the face of this certificate, shall be construed as though they were written out in full according to applicable laws or regulations:

TEN COM – as tenants in common

TEN ENT – as tenants by the entireties

JT TEN – as joint tenants with right of survivorship and not as tenants in common

UNIF GIFT MIN ACT– (Cust) Custodian (Minor) under Uniform Gifts to Minors Act (State)

Additional abbreviations may also be used though not in the above list.

For value received, ___________________________ hereby sell, assign and transfer unto

PLEASE INSERT SOCIAL SECURITY OR OTHER IDENTIFYING NUMBER OF ASSIGNEE

(PLEASE PRINT OR TYPEWRITE NAME AND ADDRESS, INCLUDING ZIP CODE, OF ASSIGNEE)

Units represented by the within Certificate, and do hereby irrevocably constitute and appoint ____________ Attorney to transfer the said Units on the books of the within named Company with full power of substitution in the premises.

Dated

Notice: The signature to this assignment must correspond with the name as written upon the face of the certificate in every particular, without alteration or enlargement or any change whatever.

Signature(s) Guaranteed:

THE SIGNATURE(S) MUST BE GUARANTEED BY AN ELIGIBLE GUARANTOR INSTITUTION (BANKS, STOCKBROKERS, SAVINGS AND LOAN ASSOCIATIONS AND CREDIT UNIONS WITH MEMBERSHIP IN AN APPROVED SIGNATURE GUARANTEE MEDALLION PROGRAM, PURSUANT TO S.E.C. RULE 17Ad-15).