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in American Journal of Veterinary Research

Objective

To determine effectiveness of large-scale distribution of an oral rabies vaccine contained in a palatable bait for halting expansion of a canine rabies epizootic in coyotes (Canis latrans).

Design

Prospective study.

Animals

98 coyotes during prevaccination surveillance and 449 coyotes and 60 other wild animals during postvaccination surveillance.

Procedure

A vaccinia recombinant oral rabies vaccine was inserted into an edible bait for coyotes that also contained tetracycline as a biomarker. Vaccine units were then distributed via aircraft, using automated distribution equipment and flight plans developed by incorporating global positioning system equipment. The target area was along the northern edge of an area that had an epizootic of canine rabies. This area was identified through previously conducted epidemiologic surveillance of rabies cases. During postvaccination surveillance, dental specimens were examined for biomarker evidence of bait acceptance, and serum samples were analyzed for rabies neutralizing antibodies.

Results

Samples from 449 coyotes were obtained during postvaccination surveillance. Seroconversion was detected in 39 of 96 (40.6%) coyotes that had evidence of tetracycline biomarker. Additionally, the number of rabies cases in the target area decreased, and expansion of the epizootic area ceased.

Clinical Implications

Mass distribution of an oral rabies vaccine in a palatable bait is an effective means to halt expansion of a rabies epizootic involving coyotes. (J Am Vet Med Assoc 1998; 212:498-502)

Free access
in Journal of the American Veterinary Medical Association

Abstract

Objective—To evaluate response rate and duration of malignant melanomas in dogs treated with carboplatin.

Design—Retrospective study.

Animals—27 client-owned dogs with spontaneously occurring measurable malignant melanomas.

Procedure—Records of dogs with melanomas treated with carboplatin from October 1989 to June 2000 were reviewed. Carboplatin was administered IV at doses of 300 or 350 mg/m2 of body surface area. Response to treatment and evidence of drug toxicity were determined.

Result—Response to treatment could be evaluated in 25 dogs. Of those, overall response rate was 28%. One dog had a complete response, 6 (24%) dogs had a partial response (> 50% reduction in tumor burden). Median duration of partial response was 165 days. Eighteen dogs had stable disease (n = 9; 36%) or progressive disease (9; 36%). Response to treatment was significantly associated with carboplatin dose on a milligram per kilogram basis (15.1 mg/kg [6.9 mg/lb] of body weight vs 12.6 mg/kg [5.7 mg/lb]). Evidence of gastrointestinal toxicosis could be assessed in 27 dogs. Mean body weight of 5 dogs that developed gastrointestinal toxicosis was significantly less than that of 22 dogs without gastrointestinal toxicosis (9.9 kg [21.8 lb] vs 19.3 kg [42.5 lb]).

Conclusions and Clinical Relevance—Carboplatin had activity against macroscopic spontaneously occurring malignant melanomas in dogs and should be considered as an adjunctive treatment for microscopic local or metastatic tumors. Gastrointestinal toxicosis was associated with body weight. Because small dogs are more likely to have adverse gastrointestinal effects, gastrointestinal protectants should be considered for these patients. (J Am Vet Med Assoc 2001;218:1444–1448)

Full access
in Journal of the American Veterinary Medical Association

Summary

Idarubicin, a new synthetic anthracycline analogue, was administered orally to 34 cats with spontaneous tumors. The maximum tolerated dosage was determined to be 2 mg/cat/d given for 3 consecutive days every 3 weeks. Anorexia and leukopenia were found to be dose limiting in cats receiving the drug at a higher dosage. The most common toxicoses seen at the maximum tolerated dosage were leukopenia, anorexia, and vomiting; however, development of toxicoses was not found to be associated with sex, FeLV test result, tumor type, dosage, age, or weight.

Idarubicin (2 mg/cat/d for 3 days, q 3 wks) was used to treat 18 cats with lymphoma in which complete remission had been achieved by administration of other chemotherapeutic agents. Median remission duration for these cats was comparable to that reported for cats treated with other protocols. We concluded that orally administered idarubicin would be useful in the treatment of cats with lymphoma.

Free access
in Journal of the American Veterinary Medical Association

Summary

Mitoxantrone was administered to 74 dogs with lymphoma at a dosage of 5.0 mg/m2 of body surface, IV, every 3 weeks. Thirty-four dogs had failed to respond to prior treatment with chemotherapeutic agents, which included doxorubicin (33 dogs). The remaining 40 dogs had not received prior treatment.

Complete remission was determined in 19 of 74 dogs (26%), 10 of which had not received prior treatment. The median duration of remission for these 10 dogs was 94 days (range, 49 to 440 days, with 2 dogs still alive at 370 and 440 days, respectively). Nine dogs that had received prior treatment had complete remission that lasted for a median of 126 days (range, 42 to 792 days, with 1 dog still alive at 792 days). The combined remission rate (complete remission plus partial remission) was 41%. Toxicosis was minimal, developing in only 9 dogs and requiring hospitalization of 2 dogs.

We concluded that the complete remission rate ascertained when mitoxantrone was the only treatment administered was low, compared with treatments that involved other chemotherapeutic agents; however, the combined remission rate of 41% indicated that mitoxantrone may be beneficial in the treatment of lymphoma in dogs.

Free access
in Journal of the American Veterinary Medical Association

Abstract

OBJECTIVE To investigate the impact of age and inferred prior vaccination history on the persistence of vaccine-induced antibody against rabies in horses.

DESIGN Serologic response evaluation.

ANIMALS 48 horses with an undocumented vaccination history.

PROCEDURES Horses were vaccinated against rabies once. Blood samples were collected prior to vaccination, 3 to 7 weeks after vaccination, and at 6-month intervals for 2 to 3 years. Serum rabies virus–neutralizing antibody (RVNA) values were measured. An RVNA value of ≥ 0.5 U/mL was used to define a predicted protective immune response on the basis of World Health Organization recommendations for humans. Values were compared between horses < 20 and ≥ 20 years of age and between horses inferred to have been previously vaccinated and those inferred to be immunologically naïve.

RESULTS A protective RVNA value (≥ 0.5 U/mL) was maintained for 2 to 3 years in horses inferred to have been previously vaccinated on the basis of prevaccination RVNA values. No significant difference was evident in response to rabies vaccination or duration of protective RVNA values between horses < 20 and ≥ 20 years of age. Seven horses were poor responders to vaccination. Significant differences were identified between horses inferred to have been previously vaccinated and horses inferred to be naïve prior to the study.

CONCLUSIONS AND CLINICAL RELEVANCE A rabies vaccination interval > 1 year may be appropriate for previously vaccinated horses but not for horses vaccinated only once. Additional research is required to confirm this finding and characterize the optimal primary dose series for rabies vaccination.

Full access
in Journal of the American Veterinary Medical Association

Abstract

Objective—To evaluate anti-inflammatory effects of several novel adenosine receptor agonists and to determine their specificity for various adenosine receptor subtypes on neutrophils, cells heterologously expressing equine adenosine receptors, or equine brain membranes.

Sample Population—Neutrophils isolated from 8 healthy horses.

Procedures—Radioligand binding experiments were performed to compare binding affinities of adenosine receptor agonists to equine adenosine A1, A2A, and A3 receptor subtypes. Effects of these agonists on endotoxin-induced production of reactive oxygen species (ROS) by equine neutrophils and roles of specific adenosine receptor subtypes and cAMP production in mediating these effects were determined.

Results—Radioligand binding experiments yielded a ranked order of affinity for the brain equine A2A receptor on the basis of 50% inhibitory concentrations (IC50) of the agonists as follows: ATL307 (IC50 = 1.9nM) and ATL313 > ATL309 and ATL310 > ATL202 > 2-([p-2- carboxyethyl] phenylethylamino)-5′-N-ethylcarboxyamidoadenosine > 5′-N-ethylcarboxamidoadenosine. Furthermore, ATL313 had approximately 100-fold greater selectivity for A2A over A1 and A3 receptors. In functional assays with equine neutrophils, the compounds inhibited endotoxin-induced ROS production and stimulated production of cAMP with the same ranked order of potency. Results of experiments performed with selective adenosine receptor antagonists indicated that functional effects of ATL313 were via stimulation of A2A receptors.

Conclusions and Clinical Relevance—Results indicated that activation of A2A receptors exerted anti-inflammatory effects on equine neutrophils and that stable, highly selective adenosine A2A receptor agonists may be developed for use in management of horses and other domestic animals with septic and nonseptic inflammatory diseases.

Full access
in American Journal of Veterinary Research

Abstract

Objective—To evaluate systemic effects of IV infusion of ATP-MgCl2 subsequent to infusion of a low dose of endotoxin in horses.

Animals—12 adult horses.

Procedure—Horses were administered endotoxin (lipopolysaccharide [LPS]) or saline (0.9% NaCl) solution, IV, during a 30-minute period. Immediately thereafter, horses in each group were infused IV with ATP-MgCl2 or saline solution. Two weeks later, horses were administered the opposite solution (LPS or saline solution), but it was followed by the same infusion as 2 weeks previously (ie, ATP-MgCl2 or saline solution). Cardiopulmonary and clinicopathologic variables, cytokine activity, and endothelin (ET) concentrations were recorded.

Results—IV infusion of ATP-MgCl2 after administration of a low dose of endotoxin failed to attenuate the cardiopulmonary, clinicopathologic, and cytokine alterations that develop secondary to endotoxin exposure. The combination of LPS and ATP-MgCl2 potentiated pulmonary hypertension, leukopenia, and neutropenia when compared with the combination of LPS and saline solution. The combination of LPS and ATP-MgCl2 resulted in thrombocytopenia. Endothelin concentration was increased in jugular venous and pulmonary arterial plasma in horses receiving LPS and ATP-MgCl2. Similar increases were not observed with LPS and saline solution.

Conclusions and Clinical Relevance—Administration of ATP-MgCl2 did not protect horses from systemic effects of experimentally induced endotoxemia. Furthermore, the use of ATP-MgCl2 during endotoxemia may worsen the cardiopulmonary and clinicopathologic status of affected horses. Because ATP and other adenine nucleotides are released from cells during shock, their potential role in the development of hemodynamic derangements, leukocyte adherence, and coagulopathies during endotoxemic episodes warrants further investigation. (Am J Vet Res 2004;65: 225–237)

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in American Journal of Veterinary Research

Abstract

Objective—To investigate individual- and community-level contextual variables as risk factors for submission of calcium oxalate (CaOx) uroliths or magnesium ammonium phosphate (ie, struvite) uroliths for dogs to a national urolith center, as determined on the basis of urolith submission patterns.

Sample Population—Records of 7,297 dogs from Ontario, Canada, with CaOx or struvite uroliths submitted to the Canadian Veterinary Urolith Centre from 1998 through 2006.

Procedures—Data were analyzed via multilevel multivariable logistic regression.

Results—Individual-level main effects and interactions significantly associated with the risk of submission of CaOx uroliths rather than struvite uroliths included age, sex, breed group, neuter status, body condition, dietary moisture content, diet type, sex-neuter status interaction, sex-age interaction, body condition-age interaction, and breed group—dietary moisture content interaction. In addition, median community family income and being located within a major urban center (ie, Toronto) were significant risk factors for submission of CaOx uroliths, compared with submission of struvite uroliths.

Conclusions and Clinical Relevance—Individual-level and dietary factors for dogs affected the risk of submission of CaOx uroliths, relative to that of struvite uroliths. Interactions among these variables need to be considered when assessing the impact of these risk factors. In addition, community-level or contextual factors (such as community family income and residing in a densely populated area of Ontario) also affected submission patterns, although most of the variance in the risk for submission of CaOx uroliths, compared with the risk for submission of struvite uroliths, was explained by individual-level factors. (Am J Vet Res 2010;71:1045–1054)

Full access
in American Journal of Veterinary Research