Not a specific recommendation, but a number of our suppliers indicate their anti-Dog Ig Abs work in IHC, so maybe worth checking with them. Just search our antibody directory (http://www.linscottsdirectory.com/search/antibodies) for Dog Ig (or IgG to omit IgA, IgM) and follow "More Info" to suppliers' data pages.
One place I have found to check for researchers experience with specific antibodies is at pabmabs.com. A good general resource and better if we all submit our own experiences. Best of luck.