Camden Partners Strategic Manager SC 13D/A Pet DRx / Camden Partners Strategic Manager ownership change

Exhibit A

Agreement of Joint Filing

     Pursuant to 13d-1(k)(1) promulgated under the Securities Exchange Act of 1934, the undersigned persons hereby agree to file with the Securities and Exchange Commission the Statement on Schedule 13D (the “Statement”) to which this Agreement is attached as an exhibit, and agree that such Statement, as so filed, is filed on behalf of each of them.

     IN WITNESS WHEREOF, the undersigned have executed this Agreement.

Dated: January 26, 2010

Camden Partners Strategic Fund III, L.P. By: Camden Partners Strategic III, LLC, its general partner
/s/ Donald W. Hughes
Name:	Donald W. Hughes
Title:	Managing Member
Camden Partners Strategic Fund III-A, L.P. By: Camden Partners Strategic III, LLC, its general partner
/s/ Donald W. Hughes
Name:	Donald W. Hughes
Title:	Managing Member

Camden Partners Strategic III, LLC By: Camden Partners Strategic Manager, LLC, its sole manager
/s/ Donald W. Hughes
Name:	Donald W. Hughes
Title:	Managing Member
Camden Partners Strategic Manager, LLC
/s/ Donald W. Hughes
Name:	Donald W. Hughes
Title:	Managing Member

Richard M. Berkeley
 

/s/ Donald W. Hughes, Attorney-in-Fact  

Donald W. Hughes
 

/s/ Donald W. Hughes  

Richard M. Johnston
 

/s/ Donald W. Hughes, Attorney-in-Fact  

David L. Warnock
 

/s/ Donald W. Hughes, Attorney-in-Fact  

Christopher W. Kersey
 

/s/ Donald W. Hughes, Attorney-in-Fact