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  • Author or Editor: Patricia M. Dowling x
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Abstract

Objective—To develop and characterize a cold-adapted live attenuated equine-2 influenza virus effective as an intranasal vaccine.

Animals—8 ponies approximately 18 months of age.

Procedures—A wild-type equine-2 virus, A/Equine/ Kentucky/1/91 (H3N8), was serially passaged in embryonated chicken eggs at temperatures gradually reduced in a stepwise manner from 34 C to 30 C to 28 C to 26 C. At different passages, infected allantoic fluids were tested for the ability of progeny virus to replicate in Madin-Darby canine kidney (MDCK) cells at 34 C and 39.5 C. Virus clones that replicated at 26 C in eggs and at 34 C in MDCK cells, but not at 39.5 C in MDCK cells, were tested for stability of the coldadapted, temperature-sensitive (ts), and protein synthesis phenotypes. A stable clone, P821, was evaluated for safety, ability to replicate, and immunogenicity after intranasal administration in ponies.

Results—Randomly selected clones from the 49th passage were all ts with plaquing efficiencies of < 10-6 (ratio of 39.5 C:34 C) and retained this phenotype after 5 serial passages at 34 C in either embryonated eggs or MDCK cells. The clone selected as the vaccine candidate (P821) had the desired degree of attenuation. Administered intranasally to seronegative ponies, the virus caused no adverse reactions or overt signs of clinical disease, replicated in the upper portion of the respiratory tract, and induced a strong serum antibody response.

Conclusion and Clinical Relevance—A candidate live attenuated influenza vaccine virus was derived by cold-adaptation of a wild-type equine-2 influenza virus, A/Equine/Kentucky/1/91, in embryonated eggs. (Am J Vet Res 2001;62:1290–1294)

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in American Journal of Veterinary Research

Abstract

Objective—To describe the degree of and variability in the level of client compliance and identify determinants of client compliance with short-term administration of antimicrobial medications to dogs.

Design—Prospective study.

Sample Population—90 owners of dogs prescribed antimicrobials.

Procedure—Eligible clients were invited to participate when antimicrobial medications were dispensed. Data were collected during a follow-up appointment by use of a client questionnaire, residual pill count, and return of an electronic medication monitoring device. Attending veterinarians also completed a questionnaire that asked them to predict client compliance. Methods of assessing compliance were compared with nonparametric tests. Generalized estimating equations were used to investigate potential determinants of compliance.

Results—Median compliance rates of 97% of prescribed container openings, 91% of days when the correct number of doses were given, and 64% of doses given on time as assessed by the electronic medication monitoring devices were significantly lower than the median compliance rates of 100% for client self-report of missing doses and pill count. Veterinarians were unable to predict client compliance. The dosage regimen significantly determined compliance. Clients giving antimicrobials once or twice daily were 9 times more likely to be 100% compliant, compared with 3 times daily dosing.

Conclusions and Clinical Relevance—The combination of reported missed doses and pill counts was a significant predictor of compliance as measured by electronic monitoring. Electronic monitoring caps provided useful information only when they were used appropriately. Asking clients about missed doses and performing pill counts are the most practical assessments of compliance in practice. (J Am Vet Med Assoc 2005;226:567–574)

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in Journal of the American Veterinary Medical Association

Abstract

Objective—To evaluate the pharmacokinetics and thermal and mechanical antinociceptive effects of a fentanyl constant rate infusion (CRI) in conscious cats.

Animals—8 healthy adult cats.

Procedures—At a ≥ 14-day interval, 7 cats received a loading dose (LD) of fentanyl (5 μg/kg, IV [administered at 0 hours]) followed by fentanyl infusion (5 μg/kg/h, IV) for 2 hours or similar administrations of equivalent volumes of 0.9% saline (NaCl) solution. One cat received only the fentanyl treatment. For both treatments, sedation and adverse events were evaluated and mechanical threshold (MT) and thermal threshold (TT) testing was performed prior to (baseline) and at predetermined times up to 26 hours after LD administration; plasma fentanyl concentrations were determined at similar times when the cats received fentanyl.

Results—Fentanyl induced mild sedation during the infusion. The only adverse effect associated with fentanyl LD administration was profuse salivation (1 cat). Saline solution administration did not significantly change MT or TT over time. For the duration of the CRI, MT and TT differed significantly between treatments, except for TT 1 hour after LD administration. For the fentanyl treatment, MT and TT were significantly higher than baseline at 0.25 to 0.75 hours and at 0.25 to 1 hour, respectively. During the fentanyl CRI, mean ± SD plasma fentanyl concentration decreased from 4.41 ± 1.86 ng/mL to 2.99 ± 1.28 ng/mL and was correlated with antinociception; plasma concentrations < 1.33 ± 0.30 ng/mL were not associated with antinociception.

Conclusions and Clinical Relevance—Fentanyl CRI (5 μg/kg/h) induced mechanical and thermal antinociception in cats.

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in American Journal of Veterinary Research

Abstract

Objective—To determine safety, efficacy, and immunogenicity of an intranasal cold-adapted modified- live equine influenza virus vaccine administered to ponies following induction of exercise-induced immunosuppression.

Design—Prospective study.

Animals—Fifteen 9- to 15-month old ponies that had not had influenza.

Procedure—Five ponies were vaccinated after 5 days of strenuous exercise on a high-speed treadmill, 5 were vaccinated without undergoing exercise, and 5 were not vaccinated or exercised and served as controls. Three months later, all ponies were challenged by nebulization of homologous equine influenza virus. Clinical and hematologic responses and viral shedding were monitored, and serum and nasal secretions were collected for determination of influenza-virus-specific antibody isotype responses.

Results—Exercise caused immunosuppression, as indicated by depression of lymphocyte proliferation in response to pokeweed mitogen. Vaccination did not result in adverse clinical effects, and none of the vaccinated ponies developed clinical signs of infection following challenge exposure. In contrast, challenge exposure caused marked clinical signs of respiratory tract disease in 4 control ponies. Vaccinated and control ponies shed virus after challenge exposure. Antibody responses to vaccination were restricted to serum IgGa and IgGb responses in both vaccination groups. After challenge exposure, ponies in all groups generated serum IgGa and IgGb and nasal IgA responses. Patterns of serum hemagglutination inhibition titers were similar to patterns of IgGa and IgGb responses.

Conclusions and Clinical Relevance—Results suggested that administration of this MLV vaccine to ponies with exercise-induced immunosuppression was safe and that administration of a single dose to ponies provided clinical protection 3 months later. (J Am Vet Med Assoc 2001;218:900–906)

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in Journal of the American Veterinary Medical Association