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  • Author or Editor: James H. Meinkoth x
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Abstract

Objective

To characterize the cellular basis of the plasma von Willebrand factor (vWf) deficiency in Doberman Pinschers with type-I von Willebrand's disease (vWd).

Animals

Five Doberman Pinschers with type-I vWd and 5 clinically normal dogs used as controls.

Procedure

Vascular endothelial cell cultures were used to measure constitutive vWf release, thrombin-stimulated vWf release, baseline intracellular vWf concentration, and vWf mRNA expression.

Results

Cells cultured from vWd-affected dogs were morphologically indistinguishable from cells cultured from control dogs, but had reductions in constitutive vWf release (6.5-fold) and vWf mRNA content (fivefold) that correlated to the reduction in plasma vWf concentration (sixfold) in these dogs. The 9.0-kb, canine vWf message was identified, using a polymerase chain reaction-amplified segment of the canine vWf gene and was similar in size to the human vWf message. The vWd cells also had reductions in baseline intracellular vWf concentration (15.6-fold) and thrombin-stimulated vWf release (14.5- fold). Additionally, it was observed that normal canine endothelial cells from different anatomic locations were heterogeneous with respect to vWf expression.

Conclusions

These findings suggest that the plasma vWf deficit in dogs with type-I vWd results from decreased endothelial cell production of vWf resulting from either decreased transcription of the vWf gene or abnormalities in mRNA processing/stability. This is similar to findings in human beings with type-I vWd.

Free access
in American Journal of Veterinary Research
in Journal of the American Veterinary Medical Association
in Journal of the American Veterinary Medical Association

Abstract

Objective—To characterize clinical and hematologic responses in dogs following experimental inoculation with Babesia gibsoni-like isolates from infected dogs in Oklahoma.

Design—Prospective study.

Animals—6 mixed-breed dogs.

Procedure—2 dogs were inoculated with organisms from a naturally infected dog, and 3 were inoculated with organisms from a second naturally infected dog (1 of these 3 dogs was splenectomized 1 week prior to inoculation). One dog was not inoculated. Complete blood counts were performed weekly.

Results—In the 5 dogs inoculated with organisms, parasites were initially detected 1 to 5 weeks after inoculation, and severity of parasitemia peaked with 1.9 to 6.0% of RBC infected by 4 to 6 weeks after inoculation. Parasitemia was easily detectable (> 0.1% of RBC infected) for 3 to 4 weeks. Clinical abnormalities included lethargy, fever, and pale mucous membranes but were mild to nearly inapparent in 2 dogs. All dogs developed regenerative anemia and marked thrombocytopenia. Thrombocytopenia developed before and lasted longer than the parasitemia. Profound but transient neutropenia was detected in some dogs. The splenectomized dog developed more severe parasitemia and anemia and more pronounced clinical abnormalities. Three dogs with intact spleens recovered without treatment.

Conclusions and Clinical Relevance—Results suggest that 2 or more genotypically distinct, but morphologically identical, small Babesia parasites can infect dogs in the United States. Compared with infection with small Babesia parasites from California, infection with these isolates resulted in less severe parasitemia and clinical abnormalities. Parasitemia was transient, indicating that identification of organisms in blood smears may be difficult in some dogs. (J Am Vet Med Assoc 2002;220:185–189)

Full access
in Journal of the American Veterinary Medical Association

Abstract

Objective

To determine whether endothelial cell (EC) von Willebrand factor (vWf) is uniformly distributed in canine blood vessels.

Design

Content of EC vWf from vascular segments was evaluated in Haütchen preparations, using immunohistochemistry. EC from femoral arteries and veins and jugular veins were grown in culture, and the intracellular content and constitutive release of vWf from these cells were measured. The amount of vWf mRNA in the cultured EC was determined.

Animals

Vascular segments for Hautchen preparations and EC for culture were obtained from 5 and 10 clinically normal, mixed-breed dogs, respectively.

Procedures

Appropriate vascular segments were removed, fixed, processed for immunohistochemistry, using a monospecific polyclonal antibody to canine vWf, and Haütchen preparations were made. Intracellular and constitutive released vWf was measured, using an ELISA, and vWf mRNA was measured by Northern blot analysis.

Results

Intact endothelial linings from femoral veins, jugular veins, vena cava, and pulmonary veins stained more intensely than femoral arteries, carotid arteries, aorta, and pulmonary veins. Constitutive release and intracellular content of vWf in cultured EC from femoral veins was about 30 times higher than that from femoral arterial EC, which was barely detectable. Similar differences were seen in amounts of mRNA.

Conclusions

There is marked diversity in EC vWf in canine vasculature that may result from differences in vWf mRNA.

Clinical Relevance

Low amounts of vWf in canine systemic arterial EC may contribute to thromboresistance of canine arteries. (Am J Vet Res 1996; 57:750–755)

Free access
in American Journal of Veterinary Research

Abstract

Objective

To determine whether canine plasma von Willebrand factor (vWf) varies between and within individuals over time and with different blood sample collection and processing procedures.

Animals

26 adult dogs and 6 pups.

Procedure

Blood was obtained from the jugular or cephalic vein daily for 8 to 19 days and weekly for 9 to 23 weeks in adult dogs and periodically up to 180 days of age in pups. Temporal variation in vWf concentration and the effect of vascular occlusion, venipuncture site, lipemia, hemolysis, anticoagulant, storage time, freeze-thawing, and centrifugation speed on plasma vWf concentration, measured by ELISA, were determined.

Results

Plasma vWf concentration varied over time. In dogs with mean vWf concentration ≥ 79 U/dl, the largest intraindividual range in vWf spanned 64 U/dl with daily and 53 U/dl with weekly sample collection. In dogs with mean vWf concentration ≤ 24 U/dl, the largest individual variation was 12 U/dl with daily and weekly sample collection. In dogs with mean vWf concentration ≥ 53 and ≤ 74 U/dl, the largest intraindividual range spanned 35 U/dl. Mean vWf concentration of pups from 3 to 180 days of age did not change. Sample hemolysis decreased mean vWf by 37%. Mean vWf concentration was 9% higher in cephalic than jugular vein samples (P = 0.056). Other sample collection/preparation procedures did not affect vWf concentration.

Conclusion

There was substantial temporal variation in vWf concentration within individual dogs.

Clinical Relevance

Multiple tests may be necessary to obtain a reliable estimate of vWf concentration in dogs. (Am J Vet Res 1996;57:1288-1293)

Free access
in American Journal of Veterinary Research

Abstract

Objective—To quantitatively determine echogenicity of the liver and renal cortex in clinically normal cats.

Animals—17 clinically normal adult cats.

Procedure—3 ultrasonographic images of the liver and the right kidney were digitized from video output from each cat. Without changing the ultrasound machine settings, an image of a tissue-equivalent phantom was digitized. Biopsy specimens of the right renal cortex and liver were obtained for histologic examination. Mean pixel intensities within the region of interest (ROI) on hepatic, renal cortical, and tissue-equivalent phantom ultrasonographic images were determined by histogram analysis. From ultrasonographic images, mean pixel intensities for hepatic and renal cortical ROI were standardized by dividing each mean value by the mean pixel intensity from the tissue-equivalent phantom.

Results—The mean (± SD) standardized hepatic echogenicity value was 1.06 ± 0.02 (95% confidence interval, 1.02 to 1.10). The mean standardized right renal cortical echogenicity value was 1.04 ± 0.02 (95% confidence interval, 1.01 to 1.08). The mean combined standardized hepatic and renal cortical echogenicity value was 1.02 ± 0.05 (95% confidence interval, 0.99 to 1.04).

Conclusions and Clinical Relevance—Quantitative determination of hepatic and renal cortical echogenicity in cats is feasible, using histogram analysis, and may be useful for early detection of diffuse parenchymal disease and for serially evaluating disease progression. (Am J Vet Res 2000;61:1016–1020)

Full access
in American Journal of Veterinary Research
in Journal of the American Veterinary Medical Association
in Journal of the American Veterinary Medical Association
in Journal of the American Veterinary Medical Association