Royce E. Roberts

Myelography and Epidurography

To summarize the points discussed in this article, Small animal myelography can be performed competently and safely without specialized equipment. The newer myelographic contrast media (iohexol, iopamidol) have less neurotoxic potential than those media previously used. Myelography is necessary for the diagnosis of many neurologic disorders in small animals. Metrizamide is no longer recommended for myelography in dogs and cats. Iohexol (Isovue) in concentration of 180 mg I/mL to 300 mg I/mL is recommended for small animal myelography. Some patients with serious spinal cord disease can exhibit normal myelograms. Recognizing abnormal myelographic patterns is the hallmark of myelographic interpretation. Anticonvulsive drugs (diazepam, pentobarbital, and phenobarbital) should be available for therapy of postmyelographic seizures. Epidurography is an effective diagnostic technique in the evaluation of canine lumbosacral compressive disease. Abnormalities identified with epidurography correlate well with surgically confirmed lesions.

Fibrosarcoma adjacent to the site of microchip implantation in a cat.

A 14-year-old spayed female domestic shorthair cat presented with an interscapular mass. A computed tomography scan, biopsy, and histological examination revealed a fibrosarcoma adjacent to a pet identification microchip. Because the cat was previously vaccinated at this site, it is not possible to establish definitive causation of the fibrosarcoma, but this is the first report of a tumor in the vicinity of a microchip in a cat. Microchip-associated tumors have been reported in rodents and dogs. Veterinarians should be aware that because inflammation may predispose felines to tumor formation, separation and observation of vaccination and implantation sites are indicated. Adherence to American Association of Feline Practitioners (AAFP) vaccination guidelines and monitoring of microchip implantation sites are recommended.

Palliation of clinical signs in 48 dogs with nasal carcinomas treated with coarse-fraction radiation therapy.

Data from 48 dogs with nasal carcinomas treated with palliative radiation therapy (PRT) were retrospectively reviewed. Factors potentially influencing resolution of clinical signs and survival after PRT were evaluated. Clinical signs completely resolved in 66% of dogs for a median of 120 days. The overall median survival time was 146 days. Duration of response to PRT was shorter in dogs that had clinical signs for <90 days before PRT. Survival times were shorter in dogs that had partial or no resolution of clinical signs after PRT than in dogs that had complete resolution of clinical signs.

Tolerance Doses of Cutaneous and Mucosal Tissues in Ring-necked Parakeets {Psittacula krameri) for External Beam Megavoltage Radiation

Abstract Currently used dosages for external-beam megavoltage radiation therapy in birds have been extrapolated from mammalian patients and often appear to provide inadequate doses of radiation for effective tumor control. To determine the tolerance doses of cutaneous and mucosal tissues of normal birds in order to provide more effective radiation treatment for tumors that have been shown to be radiation responsive in other species, ingluvial mucosa and the skin over the ingluvies of 9 ring-necked parakeets (Psittacula krameri) were irradiated in 4-Gy fractions to a total dose of either 48, 60, or 72 Gy using an isocentric cobalt-60 teletherapy unit. Minimal radiation-induced epidermal changes were present in the high-dose group histologically. Neither dose-related acute nor chronic radiation effects could be detected in any group grossly in cutaneous or mucosal tissue over a 9-month period. Radiation doses of 72 Gy in 4-Gy fractions were well tolerated in the small number of ring-necked parakeets in this initial tolerance dose study.

Iridium-192 interstitial brachytherapy as adjunctive treatment for canine cutaneous mast cell tumors.

Eleven dogs with cutaneous mast cell tumors (MCTs) were treated with surgery and iridium-192 ((192)Ir) interstitial brachytherapy. Minimum tumor doses ranged from 47.2 to 63.3 Gy. Treated tumors were classified as grade II (n=7) or III (n=4). Five dogs had recurrences with a median progression-free interval of 1391 days, and six dogs had no recurrence at a median follow-up time of 942 days. Acute adverse effects were well tolerated, and late effects were mild. One dog developed a second tumor of a different cell type in the radiation treatment field.