<PAGE>

                                                                    EXHIBIT 10.3

                                SECOND AMENDMENT

                                       TO

                             JOINT VENTURE AGREEMENT

            THIS SECOND AMENDMENT TO JOINT VENTURE AGREEMENT, effective as of
July 25, 2005 (this "AMENDMENT"), is made by and among Bridgetech Holdings
International, Inc., a Delaware corporation ("BRIDGETECH"), and Amcare Labs
International, Inc., a Delaware corporation ("AMCARE").

            WHEREAS, Bridgetech and Amcare are parties to that certain Joint
Venture Agreement, effective as of April 10, 2005 (the "JOINT VENTURE
AGREEMENT");

            WHEREAS, the parties hereto desire to amend the Joint Venture
Agreement;

            NOW, THEREFORE, in consideration of the premises and the mutual
representations, warranties, covenants and agreements set forth in this
Amendment, the parties hereto agree as follows:

            1. Defined Terms; Definitions. Capitalized terms that are used but
not defined in this Amendment shall have the meanings ascribed to such terms in
the Joint Venture Agreement.

            2. Effective Time of Amendment. This Amendment and the terms and
provisions hereof shall be effective as of the date hereof.

            3. Amendment to Section 1.1(b). Section 1.1(b) of the Joint Venture
Agreement is hereby amended by deleting the word "China" and replacing it with
the words "the Territory".

            4. Amendment to Section 3.5(e). The first sentence of Section 3.5(e)
of the Joint Venture Agreement is hereby amended by deleting the words "Newco's
financial accounts" and replacing them with the words "The financial accounts of
Newco1 and Newco2".

            5. Amendment to Section 3.5(g). Section 3.5(g) of the Joint Venture
Agreement is hereby amended by (i) deleting the first word of Section 3.5(g),
which is the word "Any", and replacing it with the words "Subject to Section
3.3(c)(vii), any" and (ii) deleting the words "subject to Section 3.3(e)(vii),"
from clause (ii) of such sentence.

            6. Amendment to Section 4.2(a). Section 4.2(a) of the Joint Venture
Agreement is hereby amended by adding the words "and their Affiliates"
immediately following the words "BRIDGETECH and AMCARE".

            7. Amendment to Section 12.11. Section 12.11 of the Joint Venture
Agreement is hereby amended by adding the following sentence to the end of
Section 12.11: "A facsimile copy of a party's signature to this Agreement and
any documents to be executed or delivered in connection herewith shall be deemed
to be an original signature."

<PAGE>

            8. Binding Effect. This Amendment shall be binding upon and inure to
the benefit of the parties hereto and their heirs, executors, administrators,
successors and permitted assigns. The Joint Venture Agreement, as amended by
this Amendment, shall remain in full force and effect following the
effectiveness of this Amendment in accordance with Section 2 hereof.

            9. Restatement of Joint Venture Agreement. The terms and provisions
of this Amendment may be incorporated into an amended and restated version of
the Joint Venture Agreement that restates, but does not further amend, the Joint
Venture Agreement as amended by this Amendment.

            10. Counterparts. This Amendment may be executed simultaneously in
two or more counterparts, any one of which need not contain the signatures of
more than one party, but all of such counterparts taken together shall
constitute one and the same Amendment. A facsimile copy of a party's signature
to this Amendment shall be deemed to be an original.

            11. Governing Law. This Amendment shall be deemed to be made in, and
in all respects shall be interpreted, construed and governed by and in
accordance with the laws of the State of Delaware.

                         (Signatures on following page.)

                                       2
<PAGE>

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

                                         BRIDGETECH HOLDINGS INTERNATIONAL, INC.

                                         By:        /s/ Thomas C. Kuhn III
                                             -----------------------------------
                                             Name:  Thomas C. Kuhn III
                                             Title: Executive Vice President
                                                    and Chief Financial Officer

                                         AMCARE LABS INTERNATIONAL, INC.

                                         By:       /s/ Mohan Chellappa
                                            ------------------------------------
                                            Name:  Mohan Chellappa
                                            Title: President

                                       3