EXHIBIT 5.1

                                 January 7, 2002

Heska Corporation
1613 Prospect Parkway
Fort Collins, Colorado 80525

      RE:   REGISTRATION STATEMENT ON FORM S-3

Ladies and Gentlemen:

      We have examined the Registration Statement on Form S-3 to be filed by you
with the Securities and Exchange Commission on or about the date hereof (the
"Registration Statement") in connection with the registration under the
Securities Act of 1933, as amended, of a total of up to 7,792,768 shares of your
Common Stock (the "Shares"). All of the Shares are issued and outstanding and
may be offered for sale for the benefit of the selling stockholders named in the
Registration Statement. The Shares are to be sold from time to time in the
over-the counter-market at prevailing prices or as otherwise described in the
Registration Statement. As your legal counsel, we have examined the proceedings
taken by you in connection with the sale of the Shares.

      It is our opinion that the Shares are legally and validly issued, fully
paid and nonassessable.

      We consent to the use of this opinion as an exhibit to the Registration
Statement and further consent to the use of our name wherever it appears in the
Registration Statement, including the Prospectus constituting a part thereof,
and any amendments thereto.

                                          Very truly yours,


                                          WILSON SONSINI GOODRICH & ROSATI
                                          Professional Corporation


                                          /s/ Wilson Sonsini Goodrich & Rosati
                                          Professional Corporation