Did some checking. In San Antonio, there is no cardiologist. Here are the available board certified internists:
Stacy R. Randall, DVM
Diplomate American College of Veterinary Internal Medicine
Doctor of Veterinary Medicine
University of Florida College of Veterinary Medicine 1990
Residency in Small Animal Internal Medicine
Purdue University College of Veterinary Medicine
1992-1995
Lucia Alvarez, DVM
Diplomate American College of Veterinary Internal Medicine
Doctor of Veterinary Medicine
Auburn University College of Veterinary Medicine 2006
Internship in Small Animal Medicine and Surgery
Veterinary Specialists of South Florida
2006-2007
Residency in Small Animal Internal Medicine
University of Tennessee College of Veterinary Medicine
2007-2010
Ronald S. Walton, DVM, MS
Diplomate American College of Veterinary Internal Medicine
Diplomate American College of Veterinary Emergency and Critical Care
Doctor of Veterinary Medicine
University of California at Davis, School of Veterinary Medicine 1986
Internship in Medicine and Surgery
University of Georgia, Athens, Georgia
1986-1987
Residency in Internal Medicine and Emergency and Critical Care Medicine Colorado State University
1994-1997
There is another female internist, but she specializes in oncology.
These are all at South Texas Veterinary Specialists.
South Texas Veterinary Specialists, LLP
503 E. Sonterra Blvd., Suite 102
San Antonio, TX 78258
210-930-8383
Fax 210-930-8040
I'd probably go for one of the two women!
If this is the mobile ultrasound vet that your GP vet uses, you should be aware that this is not the equivalent of an internist or cardiologist; this is a GP vet who has some training in sonography:
http://sonovet.us/
Here is his CV:
sonovet.us/docs/MARTIN%20HENDERSON%20-%20CV%20Only.pdf
The cost for ultrasound should be about the same, perhaps a bit more with internist because you'll also pay for history and physical. You can take the x-rays and bloodwork that you already have so no need to repeat those tests. The $1,200 quote was much higher because it included overnight critical care which I agree is not necessary assuming this was syncope or seizure. I would have also brought my dog home but I'd strongly consider a consult with an internist which would be much better quality diagnosis and treatment plan than using GP vet and mobile sonographer GP vet, esp. if you are dealing with something uncommon. And this is not the typical presentation of "everyday" degenerative valvular disease.
Pat