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  • Author or Editor: M. Beth Callan x
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Objective—To determine the effects of nonsteroidal anti-inflammatory drugs of various cyclooxygenase selectivities on hemostasis and prostaglandin expression in dogs.

Animals—8 client-owned dogs with clinical signs of osteoarthritis.

Procedures—Dogs received aspirin (5 mg/kg, PO, q 12 h), carprofen (4 mg/kg, PO, q 24 h), deracoxib (2 mg/kg, PO, q 24 h), and meloxicam (0.1 mg/kg, PO, q 24 h) for 10 days each, with an interval of at least 14 days between treatments. On days 0 and 10, blood was collected for platelet aggregation assays, thrombelastography, and measurement of lipopolysaccharide-stimulated prostaglandin E2, platelet thromboxane B2 (TXB2), and free serum TXB2 and 6-keto-prostaglandin F (PGF)-1α concentrations.

Results—Platelet aggregation decreased after treatment with aspirin and carprofen, whereas significant changes from baseline were not detected for the other drugs tested. Thrombelastograms obtained after treatment with carprofen revealed decreased maximum amplitude and α-angle, suggesting hypocoagulability. Maximum amplitude and coagulation index increased after treatment with deracoxib. Plasma concentrations of prostaglandin E2 decreased after treatment with carprofen or deracoxib, and platelet TXB2 production increased after treatment with aspirin. Serum concentrations of the prostacyclin metabolite 6-keto-PGF-1α did not change significantly after treatment with any of the drugs, although the ratio of free TXB2 to 6-keto-PGF-1α decreased slightly after treatment with carprofen and increased slightly after treatment with deracoxib.

Conclusions and Clinical Relevance—At the dosages tested, treatment with meloxicam affected platelet function minimally in dogs with osteoarthritis. Treatment with carprofen decreased clot strength and platelet aggregation. Clot strength was increased after treatment with deracoxib.

Full access
in American Journal of Veterinary Research


The sensitivity and specificity of 2 antibody tests for diagnosis of idiopathic thrombocytopenic purpura (itp) in dogs were investigated prospectively. An elisa to detect antibodies bound to the surface of platelets from affected dogs (direct test) was performed in 34 dogs with a clinical diagnosis of itp and in 21 dogs with thrombocytopenia attributable to other causes. An elisa to detect platelet-bindable antibodies in serum from affected dogs (indirect test) was performed in 32 dogs with itp and in 15 dogs with other causes of thrombocytopenia. The direct test was positive in 32 of 34 dogs with itp (sensitivity, 94%) and negative in 13 of 21 dogs with other causes of thrombocytopenia (specificity, 62%). Positive direct test results were obtained in 2 dogs with systemic lupus erythematosus, and in 1 dog each with concurrent Ehrlichia canis and Babesia canis infections, dirofilariasis, myelodysplasia, disseminated intravascular coagulation (of unknown cause), and thrombocytopenia subsequent to administration of trimethoprim/sulfadiazine, as well as in 1 dog with thrombocytopenia 14 days after a whole blood transfusion. The indirect test had positive results in 11 of 32 dogs with itp (sensitivity, 34%) and negative results in 12 of 15 dogs with other causes of thrombocytopenia (specificity, 80%). Positive indirect test results were obtained in 1 dog each with systemic lupus erythematosus, concurrent E canis and B canis infections, and thrombocytopenia subsequent to administration of trimethoprim/sulfadiazine. Detection of platelet-bound antibodies was more sensitive than detection of serumplatelet bindable antibodies in confirming a diagnosis of itp in dogs. Neither test was specific for itp. Therefore, a negative test result for platelet-bound antibodies in dogs with thrombocytopenia is helpful in excluding itp as a cause of thrombocytopenia; however, a positive test result is not specific for itp, and other causes of immune-mediated thrombocytopenia must be excluded to establish a diagnosis of itp.

Free access
in Journal of the American Veterinary Medical Association


Objective—To characterize in vitro coagulation status in a cohort of dogs with extrahepatic biliary tract obstruction (EHBO) and to evaluate these patients for hypercoagulability by means of thromboelastography.

Design—Prospective cohort study.

Animals—10 dogs with EHBO and 19 healthy control dogs.

Procedures—Partial or complete EHBO was confirmed via exploratory celiotomy. Venous blood samples were collected for evaluation of prothrombin time (PT) and activated partial thromboplastin time (APTT); fibrinogen and D-dimer concentrations; protein C and antithrombin activities; and factor VII, VIII, and XI coagulant activities in plasma as well as thromboelastography in whole blood. Thromboelastography variables were measured from the thromboelastography tracing, and a coagulation index was calculated. Thromboelastography results were compared with those of healthy control dogs previously evaluated by the same laboratory.

Results—Hypercoagulability was diagnosed in all dogs with EHBO on the basis of a high coagulation index. Thromboelastography variables, including maximal amplitude, α-angle, and coagulation index, were significantly higher, and K (clot formation time) and R (reaction time) were significantly lower in these dogs than in control dogs. All dogs with EHBO had PT and APTT within respective reference ranges. Plasma D-dimer and fibrinogen concentrations were above reference ranges in 8 and 7 dogs, respectively, and protein C and antithrombin activities were below reference ranges in 3 and 1 dogs, respectively.

Conclusions and Clinical Relevance—In vitro hypercoagulability was commonly detected in dogs with naturally occurring EHBO. The traditional view of EHBO as a disease that causes hypocoagulability may need to be reconsidered.

Full access
in Journal of the American Veterinary Medical Association