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  • Author or Editor: T. P. McDonald x
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Summary

Hematologic characteristics of 36 Greyhounds were studied and compared with characteristics of 22 non-Greyhound controls. Fourteen of the Greyhounds were tested and found to be seronegative for Ehrlichia canis and Babesia canis. Compared with the non-Greyhounds, Greyhounds had higher mean hemoglobin concentration, pcv, mean corpuscular volume, and mean cellular hemoglobin, and lower mean rbc count, hemoglobin P50 value, Hill coefficient, platelet count, and total plasma protein concentration. The lower mean hemoglobin P50 value in Greyhounds suggested that the higher mean hemoglobin concentration and pcv were not solely a result of selective breeding for superior racing abilities, but that Greyhound hemoglobin may have a greater affinity for oxygen than does the hemoglobin of non-Greyhounds.

Free access
in Journal of the American Veterinary Medical Association

Summary

Plasma von Willebrand factor antigen concentration was determined in 15 dogs with suspected hypothyroidism, in 1 dog with hyperthyroidism, and in 14 euthyroid dogs. The mean ± sem von Willebrand factor:antigen concentration in hypothyroid dogs (47.1% ± 12.6%) was significantly decreased (P <0.0005), compared with that in euthyroid dogs (94.7 ± 5.6%). Four hypothyroid dogs were given thyroxine for 1 month and all 4 had an increase in von Willebrand factor:antigen concentration. The plasma von Willebrand factor:antigen concentration was 200% in the hyperthyroid dog. Seemingly, reduced concentrations of plasma von Willebrand factor:antigen can be found in dogs in association with congenital von Willebrand disease or with von Willebrand disease acquired through hypothyroidism.

Free access
in Journal of the American Veterinary Medical Association

Abstract

Objective

To determine the RBC lifespan of Greyhounds, using an in vitro labeling technique.

Design

RBC from dogs were labeled with NHS-biotin and their disappearance measured over time to determine RBC lifespan.

Sample Population

5 Greyhounds that had been vaccinated against distemper, adenovirus 1 and 2 infections, parainfluenza, leptospirosis, parvovirus, and coronavirus infections, Bordetella bronchiseptica infection, and rabies the previous year; 3 sexually intact 14-month-old Beagles served as controls.

Procedure

After venipuncture for CBC, catheters were inserted in the cephalic vein of each dog. Butorphanol was then administered to achieve mild sedation and analgesia, and glycopyrrolate was administered to ensure maintenance of adequate heart rate during phlebotomy. Dogs were positioned in lateral recumbency; blood was removed via jugular venipuncture, using a standard laboratory donor blood bag containing citrate-phosphate-dextrose solution. Blood was transferred aseptically into sterile polystyrene containers and NHS-biotin was added. After incubation, the labeled RBC were reinfused into the dogs and the blood was allowed to recirculate for 1 hour before the first postinfusion sample was taken. At frequent intervals, blood to be analyzed was taken by jugular venipuncture, and the percentage of labeled cells was determined by flow cytometry.

Results

The mean RBC lifespan of non-Greyhounds was significantly longer than that of Greyhounds (104.3 ± 2.2 days vs 53.6 ± 6.5 days; P = 0.001). A negative linear correlation was also found between age of the Greyhounds and their RBC lifespan (P = 0.01, R2 = 0.91).

Conclusions

The shorter RBC lifespan of the Greyhounds may explain the finding of macrocytosis reported in earlier work. The reason for the shorter RBC lifespan in Greyhounds may be caused by differences in Greyhound RBC membrane structure or accelerated RBC removal from the circulation. (Am J Vet Res 1996; 57:739–742)

Free access
in American Journal of Veterinary Research

Summary

Medical records of 60 thrombocytopenic dogs in which platelet volume analysis was performed between 1984 and 1993 were reviewed. Information collected from the records included signalment, mean platelet volume, the clinical pathologist's assessment of the adequacy of the megakaryocyte population in the bone marrow, and the causes of thrombocytopenia. In all dogs, the bone marrow aspirate had been collected within 48 hours of platelet volume analysis. Sensitivity and specificity of using platelet volume analysis (mean volume ≤ 12.00 μm3 vs mean volume > 12.00 μm3) as a test for bone marrow megakaryocyte response (adequate vs inadequate) in thrombocytopenic dogs was determined. Sensitivity was 88%, specificity was 80%, predictive value of a positive test was 96%, and predictive value of a negative test was 57%. Results suggested that megathrombocytosis in a thrombocytopenic dog was a good predictor of adequate bone marrow response (normal or hyperplastic bone marrow megakaryocyte population); however, a mean platelet volume ≤ 12.00 μm3 in thrombocytopenic dogs was not strongly predictive of inadequate bone marrow response.

Free access
in Journal of the American Veterinary Medical Association

Summary

Changes in platelet indices (platelet count and platelet size) and pcv associated with thyroid disease were studied in 7 dogs with hypothyroidism and 21 cats with hyperthyroidism that were admitted to the veterinary teaching hospital. Compared with control (euthyroid) dogs, dogs with hypothyroidism had higher platelet count (P = 0.003), smaller platelet size (P = 0.01), and lower pcv (P = 0.02). Comparison of the group of hyperthyroid cats with a group of similarly aged, clinically normal cats with normal thyroxine values indicated that the group of hyperthyroid cats had significantly (P = 0.03) higher mean platelet size than did control cats, but differences were not found in mean platelet count or pcv. Results of this investigation indicate that the changes in platelet size reported in human beings with thyroid endocrinopathies also are found in animals so-affected. Although the pathogenesis of platelet abnormalities in animals with thyroid derangement is unclear and likely is multifactorial, the observed relation between platelet and erythrocyte production in this group of dogs is consistent with reports of an inverse relation between thrombocytopoiesis and erythropoiesis in iatrogenically hyperthyroid mice and in mice exposed to hypoxia.

Free access
in American Journal of Veterinary Research