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Abstract

Objective

To determine pharmacokinetic variables of mivacurium chloride after IV administration in dogs.

Animals

5 healthy Labrador Retrievers.

Procedure

Anesthesia was induced with thiopental and maintained with halothane in oxygen. Dogs were ventilated mechanically to an end-tidal PCO2 value between 35 and 40 mm Hg. Heart rate, direct blood pressure, and arterial pH were recorded throughout the experiment. Core temperature, end-tidal PCO2 , and halothane concentration were kept constant throughout the experiment. Paired blood samples for determination of plasma cholinesterase activity were collected prior to administration of a bolus of mivacurium (0.05 mg/kg of body weight), which was administered IV during a 2-second period. Arterial blood samples were obtained for determination of plasma mivacurium concentration 0, 1, 3, 5, 10, 30, 60, 120, 150, and 180 minutes after administration of mivacurium. Blood was collected into tubes containing EDTA and 0.25% echothiophate. Mivacurium concentration was determined, using reversed-phase high-performance liquid chromatography.

Results

For the trans-trans isomer, mean ± SEM volume of distribution was 0.18 ± 0.024 L/kg, median half-life was 34.9 minutes (range, 26.7 to 53.5 minutes), and clearance was 12 ± 2 ml/min/kg. For the cis-trans isomer, values were 0.31 ± 0.05 L/kg, 43.4 minutes (range, 31.5 to 69.3 minutes), and 15 ± 2 ml/min/kg, respectively. Values for the cis-cis isomer were not calculated, because it was not detectable in plasma 60 minutes after mivacurium administration in all 5 dogs.

Conclusions and Clinical Relevance

The trans-trans and cis-trans isomers of mivacurium have a long half-life and slow clearance in healthy dogs anesthetized with halothane. (Am J Vet Res 1999;60:1051-1054)

Free access
in American Journal of Veterinary Research

Objective—

To determine risk factors for, and prevalence and short- and long-term effects of, synovial fluid cavitation during distraction radiography.

Design—

Multicenter prevalence survey.

Animals—

6,649 purebred dogs comprising 129 breeds.

Procedure—

Radiographs from the PennHIP (University of Pennsylvania Hip Improvement Program) Laboratory were subjectively evaluated for evidence of cavitation. Multiple logistic regression was used to determine whether sex, breed, age, weight, distraction index (DI), or examining veterinarian was associated with cavitation. Short-term effects of cavitation were assessed by comparing DI for the hip with cavitation with DI for the contralateral hip in dogs with unilateral cavitation. Long-term effects of cavitation were assessed by comparing DI before and after cavitation was detected.

Results—

Cavitation was detected in 279 (4.2%) of the radiographs analyzed. Male dogs, Golden Retrievers, and heavier dogs were at a decreased risk for cavitation. Irish Wolfhounds, Irish Setters, Rhodesian Ridgebacks, and Weimaraners had an increased risk for cavitation. Age and DI were not risk factors for cavitation. Mean DI was 0.08 greater in hips with cavitation than in paired hips without cavitation. Significant differences were not detected between DI before and after cavitation, but only 7 dogs were included in this analysis.

Clinical Implications—

Cavitation is rare during distraction radiography and can increase measured DI. Radiographs should be routinely examined to ensure accurate reporting of DI. (J Am Vet Med Assoc 1997;210: 1294–1297

Free access
in Journal of the American Veterinary Medical Association

Abstract

Objective

To study biomechanical characteristics of the normal and surgically altered canine thoracolumbar vertebral column to determine the effects of surgery and trauma on lateral stability.

Animals

The T13-L1 vertebral motion units of 48 mixed-breed dogs were dissected free of surrounding musculature and prepared for biomechanical testing by cross-pinning the vertebral bodies and mounting in polymethylmethacrylate.

Procedure

Normal and surgically altered spinal specimens were subjected to lateral bending. The mean slope of the bending moment versus angular displacement curve and the load to failure were compared between treatment groups and significance was determined by the method of least squares (P < 0.05). Specimens were surgically altered by facetectomy, lateral fenestration, diskectomy, and combinations of these procedures. Each specimen was subjected to lateral bending to failure at a rate of 2.5 cm/min in a swing arm bending jig designed to simulate 4-point bending and subject the specimen to pure bending.

Results

Only specimens undergoing diskectomy had a significant decrease in slope and load at failure. Unilateral and bilateral facetectomies and fenestration induced a nonsignificant decrease in stiffness, compared with control specimens.

Conclusions

Fenestrations and facetectomies do not appear to increase the risk of injury to the canine thoracolumbar spinal cord during lateral bending.

Clinical Relevance

Fenestrations and facetectomies, as used in routine laminectomies, may be performed without concern for significant destabilization of the spine in lateral bending; however, it is possible that thoracolumbar spinal fractures involving only the vertebral body may significantly destabilize the spine in all modes of bending. (Am J Vet Res 1996;57:1228-1232)

Free access
in American Journal of Veterinary Research

Summary

Prior to 1988, rabies was reported only sporadically in coyotes. However, in the final 4 months of 1988, Starr County, Tex, which is situated on the US-Mexico border, experienced an epizootic of canine rabies, consisting of 6 laboratory-confirmed cases of rabies in coyotes and of 2 cases in domestic dogs. The first 3 cases were detected in coyotes, and the first case in a domestic dog was observed 84 days after the index case. Adjacent Hidalgo County reported 9 cases of rabies in dogs during the same time that rabid dogs were being reported in Starr County. In 1989, the epizootic primarily involved dogs: 15 dogs in Starr County and 19 dogs in Hidalgo County. Five rabid coyotes were reported in Starr County in 1989, and 1 rabid coyote was reported from Hidalgo County. In 1990, rabies was reported in 3 coyotes and in 31 dogs in Starr County; cases were not detected in Hidalgo County. During 1991, the epizootic expanded approximately 160 km northward, resulting in laboratory-confirmed cases in 42 coyotes and 25 dogs in 10 counties. In 1992, Webb and Willacy Counties became involved; 70 rabid coyotes and 41 rabid dogs were reported in 1992 from the 12-county area. During the first 6 months of 1993, there were 31 rabid coyotes and 38 rabid dogs reported from the same 12 south Texas counties. In May 1993, a raccoon infected with the canine rabies ecotype was reported from Cameron County. Antigenic and genetic analysis revealed the virus ecotype affecting dogs and coyotes to be that associated with urban canine rabies along the US-Mexico border.

Free access
in Journal of the American Veterinary Medical Association

Summary

Antimicrobial drug residue testing was performed on milk samples obtained from 8 cows with experimental endotoxin-induced mastitis, using 4 commercially available assay kits. Although none of the cows in the study received antimicrobials, only 1 of the 4 assay procedures, assay C, had consistently negative results (specificity = 1.00). The proportion of positive assay results varied from 0 to 1.00 among combinations of sampling time, sample status (endotoxin-infused quarter vs composite noninfused sample). The proportion of positive results found when assay C was used (0) differed significantly from the proportion found when the 3 other assays were used. The proportion of positive results did not differ significantly between assay A (0.45) and assay B (0.48); however, both assays had a significantly lower proportion of positive assays than did assay D (0.86).

Logistic regression models were developed predicting positive milk antimicrobial drug residue assay results as a function of assay kit, sample status, and time interval following experimental challenge exposure. Using assay A as a baseline risk, assay B and assay D were more likely to have positive assay results, and assay C had a decreased risk of positive assay results. Milk samples from endotoxin-infused quarters were at increased risk for positive assay results, compared with noninfused composite samples. Samples collected from endotoxin-infused quarters or control quarters were at increased risk for positive assay results following the intramammary infusion of endotoxin. Our findings suggest that specificity of milk antimicrobial drug residue assays varies greatly among assay kits and that intramammary inflammation may increase the proportion of false-positive assay results.

Free access
in Journal of the American Veterinary Medical Association

Summary:

The association of abnormal uterine discharge with the development of intramammary infection (imi) was studied in 62 multiparous Holstein cows during the nonlactating period and from lactation days 3 through 30. Duplicate milk samples were obtained from each mammary gland at approximately day 30 of the nonlactating period. Milk samples for bacteriologic culture also were obtained from each gland from all cows at the end of the previous lactation, at parturition, and on a minimum of 7 additional dates during the first 30 days of lactation. Beginning after parturition and continuing once weekly for 4 weeks, each cow was examined, using a vaginal speculum to visually estimate the quantity of abnormal uterine discharge in the vagina. Additionally, uterine swab specimens were obtained for aerobic bacteriologic culture. Cows were allotted to groups on the basis of the maximal amount of abnormal uterine discharge observed at any 1 of the 4 examinations. Cows in group 1 had normal discharge or < 30 ml of abnormal discharge; in group 2, ≥ 30 ml of abnormal discharge, observed only on examination by vaginal speculum; and in group 3, ≥ 30 ml of abnormal discharge visible externally. A difference was not detected in the development of new imi in the nonlactating period between cows that subsequently developed uterine discharge and those that did not. Although significant differences were not found, a tendency for lactating cows with abnormal uterine discharge to be at increased risk for developing new imi was observed. Direct associations were not found between aerobic bacterial species isolated from the uterus and species isolated from glands with newly developed imi during lactation. This lack of association indicated that development of imi in lactation was not likely a direct result of teat-end exposure to bacteria originating from the uterus.

Free access
in Journal of the American Veterinary Medical Association

SUMMARY

The absorption kinetics of porcine regular insulin following iv, im, and sc administration were evaluated in 10 dogs with alloxan-induced diabetes mellitus. Plasma immunoreactive insulin (iri) concentrations were evaluated immediately prior to and at 10, 20, 30, 45, 60, 90, 120, 180, and 240 minutes following iv administration; and immediately prior to and every 30 minutes for 2 hours and then every hour for 6 hours following im and sc administration of 0.55 U of porcine regular insulin/kg of body weight. Model-independent pharmacokinetic analysis was performed on each data set.

Plasma iri concentration declined rapidly after iv administration of regular insulin and then returned to baseline iri concentration by 3.2 ± 0.8 hours. The absorption kinetics following iv administration of regular insulin were similar to those found in earlier studies in healthy dogs and human beings.

The im and sc routes of regular insulin administration resulted in a pharmacologic concentration of iri at 30 minutes. The peak mean (± SD) plasma iri concentration was significantly (P < 0.05) greater following sc administratin than it was following im administration of regular insulin (263 ± 185 and 151 ± 71 IμU/ml, respectively). The time of the peak plasma iri concentration (68 ± 31 minutes and 60 ± 30 minutes) and the time to return to baseline plasma iri concentration (5.8 ± 1.2 hours and 5.8 ± 1.3 hours) were not significantly different following sc and im administration of regular insulin, respectively. The absorption kinetics following sc administration of regular insulin were similar to those found in earlier studies in healthy dogs and human beings. The absorption kinetics following im administration of regular insulin differed from those found in earlier studies and was similar to the absorption kinetics of regular insulin administered sc in this study. The reasons for this similarity were not readily apparent.

Free access
in American Journal of Veterinary Research

SUMMARY

Immunoglobulin reactions to Salmonella dublin in serum and milk from 4 groups of lactating cows were measured by an indirect elisa. The groups consisted of (1) cows that were natural carriers of S dublin in the mammary gland, (2) experimentally infected cows that did not become carriers, (3) cows inoculated with a commercial S dublin bacterin, and (4) cows used as S dublin-negative controls. Milk and serum samples were obtained at monthly intervals. Models for predicting carrier status were developed by use of stepwise logistic regression. Independent variables consisted of serum and milk IgG and IgM titers to S dublin lipopolysaccharide and a ratio of IgG to IgM. The utility of a single sample vs multiple samples obtained at 1-month or 2-month intervals was tested by comparison of goodness-of-fit χ2 P values for 8 models predicting carrier status.

Immunoglobulin reactions specific to S dublin were a significant predictor of carrier status (P < 0.001). Serum IgG titers specific for S dublin were the most important variable for predicting carrier status. Two serum IgG titers to S dublin obtained 2 months apart was a better predictor of carrier status than measurement of the IgG:IgM ratio from a single serum sample. Immunoglobulin recognizing S dublin epitopes also were detected in milk samples. In milk, performing 2 ELISA 60 days apart to determine IgG and IgM reactions to S dublin appeared to be useful for the prediction of carrier status, but was not as accurate as models for serum immunoglobulin reactions.

Free access
in American Journal of Veterinary Research

Abstract

Case Description—An 8-year-old domestic shorthair cat was evaluated because of signs of depression, circling, and visual deficits.

Clinical Findings—The cat had no cutaneous lesions, and results of an ophthalmologic examination and thoracic radiography were within reference limits. Computed tomography of the brain revealed a mass lesion involving the right parietal, temporal, and occipital lobes; the mass was in broad-based contact with the skull and smoothly marginated and had strong homogenous enhancement after contrast agent administration. During craniectomy, samples of the mass were collected for cytologic and histopathologic evaluations and microbial culture. A diagnosis of Blastomyces dermatitidis—associated meningoencephalitis with secondary pyogranulomatous inflammation was made.

Treatment and Outcome—Amphotericin B (0.25 mg/kg [0.11 mg/lb], IV) was administered on alternate days (cumulative dose, 1.75 mg/kg [0.8 mg/lb]). To minimize the risk of nephrotoxicosis, assessments of serum biochemical variables (urea nitrogen and creatinine concentrations) and urinalyses were performed at intervals. The third dose of amphotericin B was postponed 48 hours because the cat became azotemic. The cat subsequently received fluconazole (10 mg/kg [4.5 mg/lb], PO, q 12 h) for 5.5 months. Six months after discontinuation of that treatment, the cat appeared healthy and had no signs of relapse.

Clinical Relevance—Brain infection with B dermatitidis is typically associated with widespread disseminated disease. The cat of this report had no evidence of systemic disease. Blastomycosis of the CNS should be considered as a differential diagnosis for brain lesions in cats from areas in which B dermatitidis is endemic.

Full access
in Journal of the American Veterinary Medical Association

Abstract

OBJECTIVE To determine pet-related management factors associated with the carriage of antimicrobial-resistant Salmonella spp and Escherichia coli in a population of pet dogs.

SAMPLE 138 dogs from 84 households in Ontario, Canada.

PROCEDURES From October 2005 through May 2006, dogs and households in Ontario, Canada, were recruited to participate in a cross-sectional study. Fecal samples were submitted for culture of Salmonella spp and E coli, which provided 515 bacterial isolates for antimicrobial susceptibility testing. Multilevel logistic regression models with random effects for household and dog were created to identify pet-related management factors associated with antimicrobial resistance.

RESULTS Bacterial species, feeding a homemade diet or adding homemade food to the diet, feeding a raw diet or adding anything raw to the diet, feeding a homemade raw food diet, and feeding raw chicken in the past week were significant risk factors for antimicrobial resistance in this population of dogs.

CONCLUSIONS AND CLINICAL RELEVANCE In this study, several potentially important pet-related risk factors for the carriage of antimicrobial-resistant Salmonella spp and E coli in pet dogs were identified. Further evaluation of risk factors for antimicrobial resistance in dogs may lead to development of evidence-based guidelines for safe and responsible dog ownership and management to protect the public, especially pet owners who are immunocompromised.

Full access
in American Journal of Veterinary Research