Antigen Concentrations as an Indicator of Clinical Remission and Disease Relapse in Cats with Histoplasmosis.

BACKGROUND: Treatment monitoring is subjective and disease relapse is common in cats with histoplasmosis. The Histoplasma antigen enzyme immunoassay (EIA) is a noninvasive test used for determining disease remission and detecting disease relapse in humans with histoplasmosis. The utility of the antigen EIA for these purposes in cats remains unknown. HYPOTHESIS/OBJECTIVES: Those Histoplasma antigen concentrations in urine and serum would decline with antifungal treatment and that antigen elimination would be an indicator of clinical remission in cats with histoplasmosis treated with antifungal treatment. ANIMALS: Fifteen client-owned cats with histoplasmosis. METHODS: Masked observational study. Cats were monitored monthly during antifungal treatment. Time of clinical remission and serum and urine antigen elimination were determined for each cat. RESULTS: Twelve of 15 cats achieved clinical remission. At the time of diagnosis, antigen was detectable in urine in 14/15 (93%) cats and in serum in 11/15 (73%) cats. Both serum (P < .0005) and urine (P < .0001) antigen concentrations significantly decreased over time with effective treatment. Antigen elimination was sensitive [urine, 90.0% (95% CI 72.3-97.4%); serum, 90.4% (68.2-98.3%)] but less specific [urine, 64.6% (51.7-75.8%); serum, 52.1% (37.4-66.5%)] for disease remission. Urine antigen was positive in both cats and serum antigen was positive in 1 cat at the time of disease relapse. CONCLUSIONS AND CLINICAL IMPORTANCE: Measurement of Histoplasma antigen in urine and serum might be useful tests for determining disease remission and relapse in cats with histoplasmosis. Further research is needed to investigate the importance of low-level antigenemia and antigenuria.

Experimental infection of domestic cats (Felis domesticus) with Cytauxzoon manul from Pallas' cats (Otocolobus manul).

In a random, blind study, six domestic cats were assigned to two treatment groups that received either sterile water or dexamethasone by subcutaneous injection prior to intravenous inoculation with Pallas' cat (Otocolobus manul) blood infected with Cytauxzoon manul. A seventh domestic cat served as a control and was inoculated only with sterile water. Cats were monitored for clinical signs consistent with cytauxzoonosis, and periodically screened for hemoparasitemia. All domestic cats (6/6) that received Pallas' cat blood infected with C. manul developed a low but detectible parasitemia by 9 days post-inoculation, yet remained clinically healthy. All domestic cats (7/7) were subsequently challenged with Cytauxzoon felis and developed clinical signs typical of cytauxzoonosis within 5 days post-challenge. Affected animals were euthanized and cytauxzoonosis was confirmed by histopathology. While inoculation of domestic cats with Pallas' cat blood infected with C. manul induced a parasitemia, it did not cause disease or provide protection against challenge with C. felis. Further studies are warranted to determine the potential for interspecies transmission and disease with C. manul.

Quantification of hepatic and renal cortical echogenicity in clinically normal cats.

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.

The effects of a unilateral ultrasound-guided renal biopsy on renal function in healthy sedated cats.

Complications of renal biopsies are well documented except for the change in renal function after a biopsy. Eighteen healthy, adult cats were divided into two groups (n = 9 cats/group). For the measurement of global and split renal function, Group 1 used the renal uptake of 99mTc-DTPA and Group 2 used the renal uptake of 99mTc-MAG3. Scintigraphic data were collected on days (-4), (-3), 0, 1, 2, and 4 post renal biopsy. Using ultrasound guidance, biopsies were taken from the right renal cortex on dO, before acquiring scintigraphic images. P - values less than 0.10 were considered significant due to the limited number of observations. The only statistically significant change (p = 0.08) in global renal function detected was by day following a unilateral renal biopsy. Cats imaged using 99mTc-MAG3 had discernible liver activity. A unilateral, ultrasound guided renal biopsy has minimal effect on renal function in normal, healthy sedated cats.

Metastatic carcinoma presenting as hind-limb lameness: diagnosis by synovial fluid cytology.

A dog presented for evaluation of left hind-limb lameness and pain associated with manipulation of the tail. Synovial metastasis of a carcinoma was diagnosed by joint fluid examination. A primary bronchiolar-alveolar carcinoma with widespread (including synovial and skeletal) metastases was diagnosed on postmortem examination. Metastasis to synovial surfaces is uncommon, but when it occurs, the metastasis-induced arthritis may be the initial presenting complaint for which medical attention is sought. Although rarely reported, cytological examination of synovial fluid may be diagnostic. This paper presents an interesting clinical case and reviews the literature concerning metastatic disease of the synovium.

Temporal variation and factors affecting measurement of canine von Willebrand factor.

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 > or = 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 < or = 24 U/dl, the largest individual variation was 12 U/dl with daily and weekly sample collection. In dogs with mean vWf concentration > or = 53 and < or = 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.

Differential distribution of von Willebrand factor in canine vascular endothelium.

OBJECTIVE: To determine whether endothelial cell (EC) von Willebrand factor (vWf) is uniformly distributed in canine blood vessels. DESIGN: Contents of EC vWf from vascular segments was evaluated in Haütchen preparations, using immuno-histochemistry. 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 Häutchen 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.

Measurement of von Willebrand factor-specific mRNA and release and storage of von Willebrand factor from endothelial cells of dogs with type-I von Willebrand's disease.

OBJECTIVE: To characterize the cellular basis of the plasma von Willebrand factor (vWf) deficiency in Doberman Pinschers with type-1 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.

Hematological effects of 1,3,5-trinitrobenzene (TNB) in rats in vivo and in vitro.

We studied the hematological effects of single and repeated exposure to 1,3,5-trinitrobenzene (TNB) in rats. Male F-344 rats were gavaged with TNB at 35.5 and 71 mg/kg in corn oil. Blood was collected 5 h and 24 h after a single oral dose or 24 h after daily oral doses for 4 or 10 d in four different set of experiments. A dose-dependent methemoglobinemia was present only in blood collected 5 h after a single dose. A highly significant dose-dependent anemia with reduced red cells, hemoglobin, and hemotocrit was present in rats receiving TNB for 4 or 10 d. A dose-dependent decrease in serum triglycerides was present in rats receiving TNB for 10 d. There was no hemolysis when rat erythrocytes were incubated with TNB (in vitro) for 9 h. Spectral changes of hemoglobin recorded during the incubation with TNB confirm methemoglobin formation and progressive denaturation of hemoglobin-forming hemichromes. The significance of methemoglobin and hemichrome formation is discussed, and a probable hypothesis for the hemolytic anemia is suggested.

Pneumocystis carinii pneumonia in foals.

Pneumocystis carinii pneumonia was diagnosed in 3 foals. In 2 foals (No. 1 and 2), diagnosis was by histologic evaluation of pulmonary tissue. On retrospective evaluation, P carinii cysts were found on sediment smears of bronchoalveolar lavage fluid in 1 foal (No. 1). A different foal (No. 3) was diagnosed as having pneumocytosis by finding P carinii cysts in bronchoalveolar lavage fluid, and was treated successfully. Definitive diagnosis of pneumocytosis in animals is usually made at necropsy. However, careful cytologic evaluation in bronchoalveolar lavage fluid sediment can provide a diagnosis in some cases, allowing for initiation of appropriate treatment.

Ehrlichiosis in a dog with seizures and nonregenerative anemia.

Ehrlichia canis infection was diagnosed in a dog with a history of seizures and nonregenerative anemia. Serologic titer to E canis was greater than 1:100. Evaluation of CSF revealed a high cell count, high protein concentration, and a positive Pandy test result. Several mononuclear leukocytes in the CSF contained E canis morulae. Central nervous system lesions are commonly found on postmortem examination of animals with ehrlichiosis, although clinical reports of neurologic signs attributable to this disease are less common. Ehrlichiosis should be included in the differential diagnosis of CNS disease in dogs from enzootic areas.

Ehrlichiosis and polyarthritis in three dogs.

Three dogs admitted for evaluation of lameness were determined to be infected with a neutrophilic strain of Ehrlichia. Ehrlichia morulae were detected in low numbers in both synovial fluid and blood neutrophils. The dogs had rapid clinical improvement after appropriate antibiotic therapy. A diagnosis of canine ehrlichiosis easily could have been missed if morulae had not been identified. Ehrlichiosis should be considered in acutely lame dogs residing in areas enzootic for ehrlichiosis. A careful search for Ehrlichia morulae within synovial fluid and blood neutrophils should be performed. An E canis titer determination also may be helpful.