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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 the efficacy (durations of remission and survival) of an alternating-day radiation protocol for incompletely excised histologic grade-III solitary mast cell tumors (MCTs) in dogs.

Design—Retrospective study.

Animals—31 dogs.

Procedure—Radiation (52 Gy in an 18-fraction alternating-day protocol) was delivered to an area bordered by margins ≥ 3 cm around the surgical scar and to the associated local-regional lymph nodes. Dogs were not given chemotherapeutic agents concurrently or after radiation. Information on signalment, duration of remission, and survival time was obtained from medical records.

Results—Median and mean durations of remission were 27.7 and 17.0 months, respectively (range, 1 to 47 months). Median and mean durations of survival were 28 and 20 months, respectively (range, 3 to 52 months). Dogs with tumors located on the skin of the pinna, perineum, and prepuce had a median duration of remission greater than dogs with tumors located at other sites (27.7 and 14.4 months, respectively). Dogs with tumors ≤ 3 cm in maximum diameter before surgery survived longer than dogs with tumors > 3 cm (31 and 24 months, respectively). The remission rate was 65% and survival rate was 71% at 1 year after treatment. Sixteen dogs that were euthanatized had complications associated with local-regional tumor progression. Systemic metastases to liver, spleen, intestine, and bone marrow were detected in 1 dog.

Conclusions and Clinical Relevance—Without further treatment, incompletely excised grade-III mast cell tumors have high local-regional recurrence; local-regional treatment with radiation may effectively be used to manage many such tumors. (J Am Vet Med Assoc 2004;224:79–82)

Full access
in Journal of the American Veterinary Medical Association

Objective

To identify correlations between ultrasonographic findings and specific hepatic diseases in cats.

Design

Retrospective study.

Sample Population

Medical records of 72 cats with a histopathologic diagnosis of hepatic disease and diagnostic-quality abdominal ultrasonograms between 1985 and 1997.

Procedure

Abdominal ultrasonographic findings in 72 cats with histologically confirmed hepatic disease (hepatic lipidosis excluded) were reviewed. Rather than attempt to combine individual ultrasonographic findings with specific hepatic diseases, 2 classification trees were created as models to correlate certain groups of abnormalities with specific hepatic diseases or with malignant and benign lesions of the liver. Sensitivity and specificity of classification trees were calculated.

Results

Use of a classification tree resulted in correct classification of malignant versus benign hepatic lesions in 88.9% of cats that had hepatic disease (sensitivity, 90.7%; specificity, 86.1 %). Use of a classification tree to distinguish individual types of hepatic diseases resulted in mostly accurate classification of hepatic lymphosarcoma (sensitivity, 70.5%; specificity, 98.2%), cholangitis-cholangiohepatitis syndrome (sensitivity, 87%; specificity, 90%), and benign lesions of the liver (sensitivity, 84.6%; specificity, 86.4%). Criteria that helped most in differentiating among various hepatic diseases were abnormalities within other organs (spleen, lymph nodes) and appearance of the hepatic portal system. A correlation was not found between focal or multifocal appearance of hepatic lesions and specific hepatic diseases.

Clinical Implications

Use of classification trees to distinguish among specific hepatic diseases or between malignant and benign hepatic lesions provides potentially useful algorithms for ultrasonographic evaluation of cats with hepatic disease. (J Am Vet Med Assoc 1998;213:94-98)

Free access
in Journal of the American Veterinary Medical Association

Abstract

Objective

To characterize Listeria monocytogenes from tissues of channel catfish for their ability to cause hemolysis and grow intracellularly in mouse macrophages.

Samples

15 isolates from processed fillets and 15 isolates from the brain, spleen, and kidneys.

Procedure

Serotype and hemolytic activity of L monocytogenes isolates were evaluated, using plate agglutination and CAMP tests, respectively. Invasiveness of L monocytogenes was determined by inoculating each strain or isolate on J774A.1 macrophage cells. Infected cells were incubated for 0 or 3 hours and lysed; then 100 μΙ of the lysate was plated onto a brain heart infusion agar plate. Colony counts for each strain or isolate were analyzed statistically.

Results

Of 30 isolates, 19 were serotype 1 and 11 were serotype 4. Mouse J774A.1 macrophages were inoculated with catfish isolates, a wild-type (EGD) or a nonhemolytic strain of L monocytogenes. Seventy-three percent (11/15) of isolates originating from catfish organs and 100% (15/15) of isolates originating from fillets were not significantly different from the wild-type EGD strain. The nonhemolytic L monocytogenes strain used as a negative control failed to replicate. Intracellular growth of all L monocytogenes isolates decreased after an additional 3-hour incubation period with medium containing 50 μg/ml of gentamicin.

Conclusions

Similar to the wild-type EGD strain, most channel catfish L monocytogenes isolates were hemolytic, serotype 1 or 4, and were invasive for mouse J774A.1 macrophages.

Clinical Relevance

L monocytogenes growth in mouse macrophages may serve as an in vitro model for determining virulence of isolates from food products or environments. (Am J Vet Res 1998;59:1125-1128)

Free access
in American Journal of Veterinary Research

Abstract

Objectives

To determine whether the vaccine Brucella abortus strain RB51 (SRB51) would infect dogs, be shed in urine or feces, or cause placentitis and abortion.

Animals

18 Beagles.

Procedure

Males (n = 3), nonpregnant females (n = 3), and pregnant females (n = 4) were inoculated orally with SRB51; control dogs (n = 2) were fed sterile saline solution. A separate group of pregnant females (n = 5) received SRB51 IV, and their controls (n = 1) received sterile saline solution IV. Dogs were observed twice daily for evidence of abortion. Urine and feces were collected periodically for bacteriologic culture, and blood was collected for bacteriologic culture and serologic analysis. At full gestation (oral and IV inoculated pregnant females) or on postinoculation day 49 (nonpregnant females and males), dogs were euthanatized and samples were collected for bacteriologic culture and microscopic examination.

Results

Abortion was not apparent during the study, and SRB51 was not found in samples of urine or feces from any dog. Strain RB51 was isolated from retropharyngeal lymph nodes from all orally inoculated dogs (9/9). One orally inoculated and 1 IV inoculated pregnant dog had SRB51 in placental tissues. Strain RB51 was also isolated from 1 fetus from the orally inoculated female dog with placentitis, but lesions were not detected in the fetus.

Conclusions and Clinical Relevance

Oral inoculation of nonpregnant female or male dogs with SRB51 did not result in shedding in urine or feces, although oropharyngeal lymph nodes became infected; in pregnant females, it caused infection of the placenta, with resulting placentitis and fetal infection, but abortion was not apparent. Intravenous inoculation resulted in infection of maternal spleen, liver, and placenta; however, fetal infection and abortion were not observed. Infected canine placental membranes or fluids may be a source of infection for other animals and human beings. (Am J Vet Res 1997;58:851–856)

Free access
in American Journal of Veterinary Research

Summary

The role of platelet-activating factor (paf) in mediating the colonic damage that develops after large-colon torsion was studied in 14 ponies. Morphologic changes in areas of the ascending colon and selected abdominal and thoracic viscera after 1 hour of large-colon torsion and 3 to 5 hours of reperfusion were determined, as well as the protective effects of systemic administration of a specific paf antagonist (WEB 2086). Ponies were selected then allocated at random and in equal numbers to 2 groups that received 1 of 2 treatments prior to induction of large-colon torsion: group 1 —control (saline solution), and group 2 — WEB 2086 (3 mg/kg of body weight loading dose and 3 mg/kg/h for the remainder of the study). In each pony, full-thickness tissue specimens from the gastrointestinal tract —cecum, pelvic flexure, left and right ventral colon, and right dorsal colon —heart, left lung, liver, left adrenal gland, spleen, and right kidney were collected and histologically evaluated. Edema, mucosal necrosis, and neutrophil infiltration in colonic sections were graded from 0 (normal) to 3 (most severe changes). Sections of liver and lung from 3 ponies in each group, and colon from 1 pony in each group, also were examined by transmission electron microscopy to determine the presence of ultrastructural alterations.

Ischemia and reperfusion induced marked changes in all sections of colon in all ponies: moderate to severe submucosal edema, moderate necrosis of the superficial epithelium and lamina propria, and necrosis of the mucosal crypt epithelium. Extra-vascular neutrophil accumulation was evident in all sections of colon and cecum, but not in other tissues. Ultrastructural lesions were not present in hepato-cytes or pneumocytes, or in the endothelial cells of liver, lung, and colon. Bacteria were observed by electron microscopy in 5% of hepatic sinusoids. Administration of a specific paf antagonist, WEB 2086, failed to reduce severity of the observed lesions, indicating that it was not cytoprotective at the dosage used in this model of ischemia-reperfusion injury.

Free access
in American Journal of Veterinary Research

Abstract

Objective

To evaluate stable rough mutants derived from Brucella melitensis 16M and B suis 2579 (biovar 4) as vaccines against homologous and heterologous Brucella spp in the BALB/c mouse model.

Design, Animals, and Procedure

Rough mutants VTRM1 and VTRS1 were obtained from B melitensis 16M and B suis 2579, respectively, by allelic exchange of the rfbU gene encoding mannosyltransferase with a Tn5-disrupted rfbU gene. Mice were vaccinated with VTRM1 or VTRS1 and challenge exposed 8 weeks later.

Results

VTRM1 and VTRS1 replicated extensively in the spleen during the first 3 weeks of infection, then decreased rapidly. Antibodies specific for the O polysaccharide were not detected in sera of mice inoculated with either rough strain. Vaccination with VTRM1 or VTRS1 induced protection against virulent strains of B abortus (2308), B melitensis (16M), B suis biovar 1 (750), and B suis biovar 4 (2579). VTRM1 also protected against B ovis (PA) and against 4 field isolates of B abortus from bison or elk. VTRS1 conferred protection against 4 field isolates of B suis biovar 4 from reindeer. Vaccines prepared from live VTRM1 or VTRS1 provided significantly greater protection than that afforded by vaccines of killed cells in QS- 21 adjuvant. Vaccination with VTRM1 containing VTRS1 gave minimal protection against the antigenically unrelated Listeria monocytogenes, thus demonstrating the immunologic specificity of protection against Brucella spp.

Conclusions and Clinical Relevance

Results encourage evaluation, in primary host species, of VTRM1 and VTRS1, along with RB51, as alternative vaccines to strain 19, Rev 1, or other smooth phase vaccines. (Am J Vet Res 1996; 57:677–683)

Free access
in American Journal of Veterinary Research

Abstract

Objective

To characterize the pathogenic potential of a unique Borrelia isolate obtained from a dog from Florida (FCB isolate).

Design

Prospective experimental infection.

Animals

32 preweanling Swiss Webster mice and 12 adult male Hartley guinea pigs were injected intraperitoneally with 105 spirochetes.

Procedure

Mice were used as controls and blood recipients, and at 3- to 4-day intervals, 1 control mouse and 2 infected mice were necropsied, tissues were cultured, and a recipient mouse was inoculated with blood. Guinea pigs were randomized to 4 groups and inoculated intradermally with 100, 102, 103, or 104 spirochetes. For 48 days, clinical, hematologic, serologic, and microbiologic tests were performed on them, after which they were necropsied.

Results

In mice, spirochetemia was detectable between postinoculation days (PID) 3 and 13, and seroreactivity to homologous antigen was detectable during PID 10 through 31. Compared with control mice, infected mouse spleens were 2 to 3 times larger. Histologic lesions included lymphoid hyperplasia, neutrophilic panniculitis, epicarditis, and myocarditis, with intralesional spirochetes detected from PID 3 through 6. During PID 10 through 31, nonsuppurative epicarditis developed. Signs of illness and hematologic abnormalities were not observed in guinea pigs, despite isolating spirochetes from blood during PID 7 to 27. When necropsied on PID 48, histologic lesions included lymphoid hyperplasia and lymphocytic plasmacytic epicarditis.

Conclusions

The FCB isolate causes spirochetemia, lymphoid hyperplasia, dermatitis, and myocardial injury in Swiss Webster mice and can be transmitted by blood inoculation. In Hartley guinea pigs, the isolate causes spirochetemia, lymphoid hyperplasia, and epicarditis. Documentation of disease in mice, guinea pigs, and, presumably, dogs raises the level of concern that the FCB isolate might be pathogenic for man and other animal species. (Am J Vet Res 1996;57:505–511)

Free access
in American Journal of Veterinary Research

SUMMARY

Arterial blood samples were obtained at rest, just before, and 5 minutes after a 704-m race, to quantify changes in hematologic variables, plasma electrolyte and protein concentrations, osmolality, and acid/base variables. Changes in plasma volume were estimated from the change in plasma protein concentration. Immediately prior to the race, plasma volume decreased by 10% from rest and total circulating rbc volume increased by 60%, attributable to increased rbc number rather than size. Increases in blood volume (VB) by 24% and pcv by 29% also were detected before the race. Five minutes after the race, plasma volume was 21% below the resting value and total circulating rbc volume had increased 73% above the resting value, resulting in a 40% increase in pcv. Contraction of the spleen appeared responsible for increased pcv and VB before the race and maintenance of VB after the race.

Plasma chloride concentration was the same before and after the race; the chloride content of the plasma decreased by the same fraction (22%) as did the plasma volume, indicating Cl- loss from the plasma. Plasma Na+ content decreased by a smaller fraction (13%), causing Na+ concentration to increase from 151 mEq/L at rest to 167 mEq/L after the race. Assuming that Na+ concentration was the same throughout the extracellular fluid, H2O likely moved into the intracellular compartment. As a consequence of these changes, the inorganic strong ion difference in plasma increased by about 16 mEq/L, tending to minimize the acid/base disturbance induced by the 33 mEq/L increase in lactate concentration.

Results indicated that the physiologic changes taking effect during strenuous sprint exercise in Greyhounds enhance blood volume and aid in acid/base homeostasis, both of which are adaptive for this type of exercise.

Free access
in American Journal of Veterinary Research

Summary

The reticulum and adjacent organs were examined ultrasonographically in 51 cows by use of a 3.5- MHz linear transducer applied to the ventral aspect of the thorax over the sixth and seventh intercostal spaces. Examination included assessment of the contour of the reticulum, of reticular contractions, and of the organs adjacent to the reticulum.

The normal reticulum appeared as a half-moon shaped structure with a smooth contour; it contracted at regular intervals and was situated immediately adjacent to the diaphragm and ventral portion of the abdominal wall when relaxed. Contents of the reticulum could not normally be imaged because of its partly gaseous composition. The ruminoreticular groove, craniodorsal blind sac of the rumen, and the ventral sac of the rumen were observed caudally. The distal aspect of the spleen and parts of the omasum, abomasum, and liver could be imaged.

Reticular motility was characterized by a biphasic contraction pattern. Four biphasic reticular contractions usually were observed during a 4-minute period. During the first (incomplete) contraction, the reticulum contracted by a mean of 7.2 ± 2.30 cm. There was then low-grade, incomplete relaxation of the reticulum, followed immediately by the second reticular contraction, during which the reticulum usually disappeared from the 17.5-cm-deep screen. The reticulum then reappeared in its normal position. The first reticular contraction lasted a mean of 2.6 ± 0.33 seconds and the second contraction lasted 3.9 ± 0.55 seconds. The mean interval between 2 biphasic contractions was 44.9 ± 10.53 seconds. The speed of the first reticular contraction was 5.4 ± 1.32 cm/s. Ultrasonography was useful for assessing the contour and motility of the reticulum.

Free access
in American Journal of Veterinary Research