Feline leukemia virus detection by immunohistochemistry and polymerase chain reaction in formalin-fixed, paraffin-embedded tumor tissue from cats with lymphosarcoma.

The prevalence of feline leukemia virus (FeLV) antigen and DNA was assessed in formalin-fixed, paraffin-embedded tumor tissues from 70 cats with lymphosarcoma (LSA). Tissue sections were tested for FeLV gp70 antigen using avidinbiotin complex (ABC) immunohistochemistry (IHC); DNA was extracted and purified from the same tissue blocks for polymerase chain reaction (PCR) amplification of a 166 base pair region of the FeLV long terminal repeat (LTR). Results were related to antemortem FeLV enzyme-linked immunosorbent assay (ELISA) for serum p27 antigen, anatomic site of LSA, and patient age. Viral DNA was detected by PCR in 80% of cases and viral antigen by IHC in 57% of cases. Seventeen cases were PCR-positive and IHC-negative; one case was PCR-negative and IHC-positive. Clinical records included FeLV ELISA results for 30 of 70 cats. All 19 ELISA-positive cats were positive by PCR and IHC; of the 11 ELISA-negative cats that were negative by IHC, seven were positive by PCR. When evaluated according to anatomic site, FeLV DNA and antigen were detected less frequently in intestinal LSAs than in multicentric and mediastinal tumors. Lymphosarcoma tissues from cats < 7 yr were several fold more likely to be positive for FeLV antigen by IHC than were tumors from cats > or = 7 yr. However, there was no significant difference in PCR detection of FeLV provirus between LSAs from cats < 7 yr and those > or = 7 yr.(ABSTRACT TRUNCATED AT 250 WORDS)

Immunoscintigraphic detection of primary and metastatic spontaneous canine osteosarcoma with F(ab')2 fragments of osteosarcoma-associated monoclonal antibody TP-1.

Monoclonal antibody TP-1 has been shown to bind selectively to human and canine osteosarcoma cells in vitro using immunohistochemical stains. This report describes the in vivo administration of radioiodinated F(ab')2 fragments of monoclonal antibody TP-1 in dogs with primary and/or metastatic spontaneous osteosarcoma. Two dogs were injected with 131labeled F(ab')2 TP-1 and two dogs were injected with 123labeled antibody fragments. Immunoscintigraphy successfully demonstrated the radiolabeled antibody fragments in 6/6 known primary or metastatic lesions and in addition detected 4 metastatic lesions not diagnosed by conventional radiographs. Concurrent imaging of 99mTc labeled autologous erythrocytes in two dogs confirmed that the accumulation of radiolabeled antibody fragments was independent of the blood pool. There was no immunoscintigraphic evidence of localization of radioiodine to normal organs or tissues other than those expected to accumulate free iodine. The present study has demonstrated the potential of monoclonal antibody TP-1 F(ab')2 fragments for early detection of metastatic spread of spontaneous osteosarcoma.

Pharmacological relaxation of the urethra in male cats: a study of the effects of phenoxybenzamine, diazepam, nifedipine and xylazine.

Urethral pressure profiles (UPPs) were recorded in ten adult healthy male cats before and after administration of either phenoxybenzamine, diazepam, nifedipine or xylazine. A significant decrease (p less than 0.05) in urethral pressure at the level of the prostate was observed following treatment with all drugs. Xylazine produced a significant decrease in urethral pressure 4 to 7 cm from the tip of the penis in healthy male cats. None of the drugs used decreased urethral pressure in the zones of pure striated muscle or pure smooth muscle in these cats, making current recommendations for pharmacological management of urethral spasm suspect. Further studies are necessary to evaluate clinical cases of urethral spasm and to study the effects of these drugs on the urethral pressure of cats suffering from this spasm.

Serum thyroxine concentrations following fixed-dose radioactive iodine treatment in hyperthyroid cats: 62 cases (1986-1989).

The medical records of 62 hyperthyroid cats treated with a fixed dose of 4 mCi of radioactive iodine (131I) were reviewed. In 60 cats, serum thyroxine concentrations were determined after treatment, allowing evaluation of treatment success. Eighty-four percent of the cats had normal serum thyroxine concentrations after treatment. Five of the 60 cats (8%) remained hyperthyroxinemic after treatment. Five cats (8%) were hypothyroxinemic when evaluated within 60 days of treatment. Three of these cats had normal serum thyroxine concentrations 6 months after treatment, and none had clinical signs of hypothyroidism. The administration of a fixed dose of 4 mCi of 131I was determined to be an effective treatment for feline hyperthyroidism.

Whole blood platelet aggregation in dogs with liver disease.

Whole blood platelet aggregation was determined in response to collagen, arachidonic acid, and adenosine diphosphate in 20 dogs with liver disease and in 20 control dogs. Platelet aggregation in response to collagen and arachidonic acid was reduced in dogs with liver disease, compared with control dogs (P less than 0.05), whereas there was no significant difference in platelet response to adenosine diphosphate between the 2 groups of dogs. Adenosine diphosphate was found not to be a reliable aggregation agent for determination of whole blood platelet aggregation in dogs. Dogs whose platelets did not aggregate in response to collagen and/or arachidonic acid manifested bleeding tendencies that could be attributed to platelet dysfunction.

Whole blood platelet aggregation in uremic dogs.

Whole blood platelet aggregation responses to collagen, arachidonic acid, and adenosine diphosphate were determined by use of the impedance method in 22 dogs with serum urea concentrations greater than or equal to 20 mmol/L, which was attributable to renal disease, and in 25 healthy control dogs. The median changes in impedance for the control dogs were 23 ohms for collagen, 18 ohms for arachidonic acid, and 6 ohms for adenosine diphosphate. The median changes in impedance in uremic dogs were 25 ohms for collagen, 21 ohms for arachidonic acid, and 15 ohms for adenosine diphosphate. There were no significant differences in platelet aggregation responses to collagen, arachidonic acid, and adenosine diphosphate between uremic and control dogs. Hemorrhagic tendencies were not detected in uremic dogs by use of whole blood platelet aggregation. Results of this study suggest that platelet aggregation by use of the whole blood platelet aggregometer is not abnormal in uremic dogs, but does not exclude the possibility of a platelet aggregation defect undetected by the whole blood system.

Drugs used for disorders of coagulation.

Bleeding and thrombosis are altered states of hemostasis. Inhibition of normal hemostatic mechanisms results in spontaneous hemorrhage, whereas excessive hemostasis results in thrombus formation. The drugs used to prevent and treat thrombosis and those used to arrest bleeding are the subjects of this article.

Serum thyroxine concentrations after radioactive iodine therapy in cats with hyperthyroidism.

Thirty-one cats with hyperthyroidism were given one dose of radioactive iodine (131I) IV. Serum thyroxine (T4) concentrations were measured before treatment in all cats, at 12-hour intervals after treatment in 10 cats, and at 48-hour intervals after treatment in 21 cats. Serum T4 concentrations also were measured one month after 131I therapy in 29 cats. Activity of 131I administered was 1.5 to 6.13 mCi, resulting in a dose of 20,000 rads to the thyroid. Serum T4 concentrations before 131I administration were 5.3 to 51.0 micrograms/dl, with a median T4 concentration of 11.0 micrograms/dl. Serum T4 decreased most rapidly during the first 3 to 6 days after treatment. Sixteen cats (55%) had normal serum thyroxine concentrations by day 4 after 131I administration, and 23 cats (74%) were euthyroxinemic by day 8 after treatment. One month after administration of 131I, the 29 cats evaluated were clinically improved, and 24 (83%) of the 29 cats evaluated had normal serum T4 concentrations, 3 cats (10%) remained hyperthyroxinemic, and 2 cats (7%) were hypothyroxinemic. Therefore, administration of 131I was a safe and effective method to quickly decrease serum T4 concentrations in hyperthyroid cats.

Digestion of bentiromide and absorption of xylose in healthy cats and absorption of xylose in cats with infiltrative intestinal disease.

The digestion of bentiromide and the absorption of D-xylose was measured in 17 clinically healthy cats. The plasma xylose concentrations of the healthy cats were compared with values from 9 cats with diffuse infiltrative intestinal disease. The cats were administered 16.7 mg of bentiromide/kg and 0.5 g of xylose/kg via a stomach tube. Plasma samples were obtained before administration and 30, 60, 90, and 120 minutes after administration. The maximum mean plasma p-aminobenzoic acid concentration occurred at 60 minutes, with a value of 386 +/- 134 micrograms/dl (mean +/- SD). The maximum mean plasma xylose concentration also occurred at 60 minutes, with a value of 26.0 +/- 9.2 mg/dl. Plasma concentrations of p-aminobenzoic acid and xylose were lower in healthy cats than those reported for healthy dogs. There was no significant difference between xylose concentrations in healthy cats and cats with infiltrative intestinal disease.