1. William R. Prichard Veterinary Medical Teaching Hospital, University of Texas M.D. Anderson Cancer Center, Houston, Texas.
2. Veterinary Surgical and Radiological Sciences, University of Texas M.D. Anderson Cancer Center, Houston, Texas.
3. Departments of Veterinary Pathology, Microbiology and Immunology, University of Texas M.D. Anderson Cancer Center, Houston, Texas.
4. Division of Pediatrics, University of Texas M.D. Anderson Cancer Center, Houston, Texas.