Prevalence of low automated platelet counts in cats: comparison with prevalence of thrombocytopenia based on blood smear estimation

Abstract: True thrombocytopenia is uncommon in cats; however, low platelet counts frequently are found using automated cell counters. Although this discrepancy is a well known problem, the prevalence of low automated platelet counts in feline blood samples has not been documented. We retrospectively compared the prevalence of low automated platelet counts with low blood smear-estimated platelet counts in feline blood samples. Results of blood sample analysis from 359 cats during a 1-year period at the University of Glasgow Veterinary Haematology Laboratory were examined. Smear estimates of platelet number were done in those cases in which records did not indicate adequate platelet numbers. Platelet counts obtained with an impedance counter (Minos Vet, Abx Hematologie) were <200×10⁹ cells/L in 256 samples (71%) and <50×10⁹ cells/L in 43 samples (12%). However, based on estimation of platelet numbers from blood smears, only 11 samples (3.1%) had platelet counts of <200×10⁹ cells/L and 9 samples (2.5%) had counts of <50×10⁹ cells/L. Four cats with thrombocytopenia estimated by blood smear evaluation had clinical signs of a bleeding disorder. Disorders associated with thrombocytopenia included neoplasia, cytotoxic chemotherapy, and infectious diseases. There was no evidence that delay due to mailing of samples was associated with lower automated platelet counts than would have been obtained on the day of sampling. The high prevalence of apparent thrombocytopenia in automated platelet counts was attributed to a combination of platelet aggregation and the impedance method of cell differentiation by size. Vigilance and careful examination of blood smears is required to identify the few cats with true thrombocytopenia.     

Effects of cimetidine and ranitidine on basal gastric pH, free and total acid content in pigs

The effects of intramuscular administration of multiple doses of cimetidine and ranitidine on basal gastric pH, free and total acid content from young adult pigs were studied. Cimetidine (4.5 mg kg-1, four times a day, intramuscularly, for three days) significantly (P less than 0.05) raised the basal gastric pH above 3.5 with a simultaneous reduction in free acid content at two, three and 26 hours after the administration of the eighth dose. Ranitidine (0.75 mg kg-1, four times a day, intramuscularly, for three days) significantly (P less than 0.05) raised the basal gastric pH above 3.5 with a concomitant reduction in free acid content at three and 38 hours after the administration of the eight dose. Neither cimetidine nor ranitidine had any significant effects on total acid content. These results confirm that the pig is a basal acid secretor and that the pharmacodynamics and pharmacokinetics of cimetidine and ranitidine in pigs might be different from those in humans.     

Response of Pasteurella haemolytica to erythromycin and dexamethasone in calves with established infection.

A subcutaneous soft tissue infection model in calves was used to study the in vivo response of Pasteurella haemolytica to erythromycin and dexamethasone. Two tissue chambers were implanted SC in each of 12 calves. At 45 days after implantation, all tissue chambers were inoculated with an erythromycin-sensitive strain of P haemolytica. Starting 24 hours after inoculation, calves were allotted to 4 groups of equal size and a 2 x 2-factorial arrangement of treatments was applied: 3 calves were given erythromycin (30 mg/kg of body weight, IM, for 5 days), 3 calves were given dexamethasone (0.05 mg/kg, IM, for 2 days), 3 calves were given erythromycin and dexamethasone, and the remaining calves served as nontreated controls. Chamber fluids were tested daily, and the response to treatment was measured. Neither erythromycin nor dexamethasone affected viability or growth of bacteria within tissue chambers. Dexamethasone had no effect on the influx of neutrophils into infected chambers. Despite repeated administration of a high dose of erythromycin and attainment of adequate concentration in serum, erythromycin concentration in chamber fluids did not exceed the minimal inhibitory concentration established in vitro. These results indicate that the clinical efficacy of erythromycin against P haemolytica sequestered in consolidated pneumonic lesions may not be well correlated with predictions based on serum pharmacokinetic and in vitro susceptibility data.     

Infectivity of three Anaplasma marginale isolates for Dermacentor andersoni

Three isolates of Anaplasma marginale--Virginia (VAM), Illinois (IAM), and Florida (FAM)--were compared for infectivity for Dermacentor andersoni. The isolates were selected, in part, because of a tail-like appendage that has been demonstrated in the VAM and IAM, but not in the FAM. Ticks were exposed to the isolates as nymphs either naturally by feeding on a calf with anaplasmosis or artificially by percutaneous inoculation with infected bovine erythrocytes. They were examined for infectivity after molting to the adult stage by determining their capability to transmit the disease to susceptible calves and by demonstrating colonies in tick gut sections. Only those ticks exposed to the VAM proved to be infected with A marginale; ticks naturally exposed and those artificially infected with this isolate transmitted the disease to susceptible calves. Colonies of A marginale were observed only in gut tissues of ticks naturally infected with VAM. The IAM (appendage present) and FAM (appendage absent) could not be found in ticks exposed by either method, indicating that factors other than the presence of inclusion appendages may be involved in infection of ticks by A marginale.     

Demonstration of Anaplasma marginale in hemolymph of Dermacentor andersoni by animal inoculation and by fluorescent-antibody technique

Hemolymph was collected from adult Dermacentor andersoni Stiles that had been infected with Anaplasma marginale Theiler as nymphs. Before hemolymph was collected, the adult ticks were either incubated and unfed at 37 C for 2.5 days or fed for 6 days on sheep. Hemolymph collected from groups of 100 ticks was inoculated into susceptible splenectomized calves. Smears of hemolymph from the same groups of ticks were prepared for examination by fluorescent antibody technique. Hemolymph from incubated ticks caused anaplasmosis in 2 of 4 trials, and hemolymph from feeding ticks caused anaplasmosis in 4 of 4 trials. Moderately fluorescing bodies were demonstrated in some hemocytes from incubated ticks, whereas hemocytes from feeding ticks contained numerous clusters of brightly fluorescing bodies. Fluorescing bodies were not observed in hemocytes from control ticks.     

Synthesis of polycrystalline chalcopyrite semiconductors by microwave irradiation

Polycrystalline samples of the chalcopyrites CulnS(2), CulnSe(2), and CulnSSe were Prepared from stoichiometric mixtures of the pure elements by microwave irradiation. The reactions were performed in sealed quartz tubes in as few as 3 minutes. The products were analyzed by x-ray diffraction, scanning electron microscopy, energy dispersive x-ray analysis, and x-ray photoelectron spectroscopy. The surface morphology and shape of the particles produced by this method suggest that the products are formed from liquid melts. This method could be applied to the production of bulk chalcopyrite as sources for thin film growth.     

Medical and surgical management of uroperitoneum in a foal

A 4-day-old, male, American paint foal was presented for abdominal distention, respiratory distress, and diarrhea. Bladder rupture and uroperitoneum were diagnosed following abdominal ultrasonography and abdominocentesis. The defect in the dorsocranial part of the bladder wall was surgically repaired.     

Transient cold agglutinins associated with Mycoplasma cynos pneumonia in a dog

This report details a case of reversible cold agglutinins in a dog with Mycoplasma cynos pneumonia. An 11‐month‐old female spayed Rhodesian Ridgeback was presented for lethargy and cough. Thoracic radiographs revealed an alveolar pattern present bilaterally in the cranioventral lung lobes. Septic neutrophilic inflammation with suspected Mycoplasma sp. organisms was noted on cytologic examination of a trans‐tracheal wash, and the dog was treated empirically with IV ampicillin/sulbactam and enrofloxacin pending culture results. Red blood cell agglutination was noted unexpectedly on several blood film reviews during hospitalization; however, the dog never developed clinical or laboratory evidence of hemolysis. Cold agglutinins were demonstrated based on the results of a saline dilution and cold agglutinin test that showed agglutination at 4°C but not at room temperature (21°C) or 37°C. Based on a positive culture for M cynos, the dog was treated for 8 weeks with oral enrofloxacin. After clinical and radiographic resolution of the pneumonia, repeated saline dilution and cold agglutinin tests of peripheral blood were negative at all temperatures. Reversible, asymptomatic cold agglutinins are common in human patients with mycoplasma pneumonia, but this is the first reported case in a dog.