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  • Author or Editor: Michael A. Paul x
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Abstract

Objective—To determine effects of vaccination protocols with modified-live porcine reproductive and respiratory syndrome virus (PRRSV) vaccine on persistence and transmission of virus in pigs infected with a homologous isolate and determine clinical and virologic responses following heterologous viral challenge.

Animals—Four hundred forty 6- to 8-week-old PRRSV-naïve pigs.

Procedures—Pigs were allocated into 5 groups. Groups A to D were inoculated with wild-type PRRSV VR2332. Group A (positive control pigs) received PRRSV only. Groups B, C, and D received modified-live PRRSV vaccine (1, 2, or 3 doses). Group E served as a negative control group. To evaluate viral transmission, sentinel pigs were introduced into each group at intervals from 37 to 67, 67 to 97, and 97 to 127 days postinoculation (DPI). To evaluate persistence, pigs were euthanized at 37, 67, 97, or 127 DPI. To assess clinical and virologic response after challenge, selected pigs from each group were inoculated at 98 DPI with a heterologous isolate (PRRSV MN-184).

Results—Mass vaccination significantly reduced the number of persistently infected pigs at 127 DPI. Vaccination did not eliminate wild-type PRRSV; administration of 2 or 3 doses of modified-live virus vaccine reduced viral shedding after 97 DPI. Previous exposure to wild-type and vaccine virus reduced clinical signs and enhanced growth following heterologous challenge but did not prevent infection.

Conclusions and Clinical Relevance—Findings suggest that therapeutic vaccination may help to reduce economic losses of PRRSV caused by infection; further studies to define the role of modified-live virus vaccines in control-eradication programs are needed.

Full access
in American Journal of Veterinary Research

Abstract

Objective—To compare pharmacokinetics after IV, IM, and oral administration of a single dose of meloxicam to Hispaniolan Amazon parrots (Amazona ventralis).

Animals—11 healthy parrots.

Procedures—Cohorts of 8 of the 11 birds comprised 3 experimental groups for a crossover study. Pharmacokinetics were determined from plasma concentrations measured via high-performance liquid chromatography after IV, IM, and oral administration of meloxicam at a dose of 1 mg/kg.

Results—Initial mean ± SD plasma concentration of 17.3 ± 9.0 μg/mL was measured 5 minutes after IV administration, whereas peak mean concentration was 9.3 ± 1.8 μg/mL 15 minutes after IM administration. At 12 hours after administration, mean plasma concentrations for IV (3.7 ± 2.5 μg/mL) and IM (3.5 ± 2.2 μg/mL) administration were similar. Peak mean plasma concentration (3.5 ± 1.2 μg/mL) was detected 6 hours after oral administration. Absolute systemic bioavailability of meloxicam after IM administration was 100% but was lower after oral administration (range, 49% to 75%). Elimination half-lives after IV, IM, and oral administration were similar (15.9 ± 4.4 hours, 15.1 ± 7.7 hours, and 15.8 ± 8.6 hours, respectively).

Conclusions and Clinical Relevance—Pharmacokinetic data may provide useful information for use of meloxicam in Hispaniolan Amazon parrots. A mean plasma concentration of 3.5 μg/mL would be expected to provide analgesia in Hispaniolan Amazon parrots; however, individual variation may result in some birds having low plasma meloxicam concentrations after IV, IM, or oral administration. After oral administration, meloxicam concentration slowly reached the target plasma concentration, but that concentration was not sustained in most birds.

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in American Journal of Veterinary Research

Abstract

Objective—To evaluate bacterial and protozoal contamination of commercially available raw meat diets for dogs.

Design—Prospective longitudinal study.

Sample Population—240 samples from 20 raw meat diets for dogs (containing beef, lamb, chicken, or turkey), 24 samples from 2 dry dog foods, and 24 samples from 2 canned dog foods.

Procedure—Each product was purchased commercially on 4 dates approximately 2 months apart. Three samples from each product at each sampling period were evaluated via bacterial culture for non–type-specific Escherichia coli (NTSEC), Salmonella enterica, and Campylobacter spp. Antimicrobial susceptibility testing was performed on selected isolates. Polymerase chain reaction assays were used to detect DNA from Cryptosporidium spp, Neospora spp, and Toxoplasma spp in samples obtained in the third and fourth sampling periods.

Results—One hundred fifty-three of 288 (53%) samples were contaminated with NTSEC. Both raw and prepared foods contained NTSEC during at least 1 culture period. Salmonella enterica was recovered from 17 (5.9%) samples, all of which were raw meat products. Campylobacter spp was not isolated from any samples. In 91 of 288 (31.6%) samples, there was no gram-negative bacterial growth before enrichment and in 48 of 288 (16.7%) samples, there was no aerobic bacterial growth before enrichment. Susceptibility phenotypes were variable. Cryptosporidium spp DNA was detected in 3 samples.

Conclusions and Clinical Relevance—Bacterial contamination is common in commercially available raw meat diets, suggesting that there is a risk of foodborne illness in dogs fed these diets as well possible risk for humans associated with the dogs or their environments.

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in Journal of the American Veterinary Medical Association

Abstract

Objective—To determine the onset of immunity after IM administration of a single dose of a recombinant canarypox virus vaccine against West Nile virus (WNV) in horses in a blind challenge trial.

Animals—20 mixed-breed horses.

Procedure—Horses with no prior exposure to WNV were randomly assigned to 1 of 2 groups (10 horses/group). In 1 group, a recombinant canarypox virus vaccine against WNV was administered to each horse once (day 0). The other 10 control horses were untreated. On day 26, 9 treated and 10 control horses were challenged via the bites of mosquitoes (Aedes albopictus) infected with WNV. Clinical responses and WNV isolation were monitored for 14 days after challenge exposure; antibody responses against WNV after administration of the vaccine and challenge were also assessed in both groups.

Results—Following challenge via WNV-infected mosquitoes, 1 of 9 treated horses developed viremia. In contrast, 8 of 10 control horses developed viremia after challenge exposure to WNV-infected mosquitoes. All horses seroconverted after WNV challenge; compared with control horses, antibody responses in the horses that received the vaccine were detected earlier.

Conclusions and Clinical Relevance—In horses, a single dose of the recombinant canarypox virus-WNV vaccine appears to provide early protection against development of viremia after challenge with WNVinfected mosquitoes, even in the absence of measurable antibody titers in some horses. This vaccine may provide veterinarians with an important tool in controlling WNV infection during a natural outbreak or under conditions in which a rapid onset of protection is required. (Am J Vet Res 2004;65:1459–1462)

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in American Journal of Veterinary Research

Abstract

Objective—To determine the effect of long-term administration of enalapril on renal function in dogs with severe, compensated mitral regurgitation.

Design—Randomized controlled trial.

Animals—139 dogs with mitral regurgitation but without overt signs of heart failure.

Procedure—Dogs were randomly assigned to be treated with enalapril (0.5 mg/kg [0.23 mg/lb], PO, q 24 h) or placebo, and serum creatinine and urea nitrogen concentrations were measured at regular intervals for up to 26 months.

Results—Adequate information on renal function was obtained from 132 dogs; follow-up time ranged from 0.5 to 26 months (median, 12 months). Mean serum creatinine and urea nitrogen concentrations were not significantly different between dogs receiving enalapril and dogs receiving the placebo at any time, nor were concentrations significantly different from baseline concentrations. Proportions of dogs that developed azotemia or that had a ≥ 35% increase in serum creatinine or urea nitrogen concentration were also not significantly different between groups.

Conclusions and Clinical Relevance—Results suggest that administration of enalapril for up to 2 years did not have any demonstrable adverse effects on renal function in dogs with severe, compensated mitral regurgitation. (J Am Vet Med Assoc 2002;221: 654–658)

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in Journal of the American Veterinary Medical Association

Abstract

Objective—To determine the efficacy of long-term enalapril administration in delaying the onset of congestive heart failure (CHF).

Design—Placebo-controlled, double-blind, multicenter, randomized trial.

Animals—124 dogs with compensated mitral valve regurgitation (MR).

Procedures—Dogs randomly assigned to receive enalapril or placebo were monitored for the primary endpoint of onset of CHF for ≤ 58 months. Secondary endpoints included time from study entry to the combined endpoint of CHF-all-cause death; number of dogs free of CHF at 500, 1,000, and 1,500 days; and mean number of CHF-free days.

Results—Kaplan-Meier estimates of the effect of enalapril on the primary endpoint did not reveal a significant treatment benefit. Chronic enalapril administration did have a significant benefit on the combined endpoint of CHF-all-cause death (benefit was 317 days [10.6 months]). Dogs receiving enalapril remained free of CHF for a significantly longer time than those receiving placebo and were significantly more likely to be free of CHF at day 500 and at study end.

Conclusions and Clinical Relevance—Chronic enalapril treatment of dogs with naturally occurring, moderate to severe MR significantly delayed onset of CHF, compared with placebo, on the basis of number of CHF-free days, number of dogs free of CHF at days 500 and study end, and increased time to a combined secondary endpoint of CHF-all-cause death. Improvement in the primary endpoint, CHF-free survival, was not significant. Results suggest that enalapril modestly delays the onset of CHF in dogs with moderate to severe MR.

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in Journal of the American Veterinary Medical Association
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in Journal of the American Veterinary Medical Association