Serum samples from 593 white-tailed deer in Pennsylvania that were killed by hunters in 1991 were examined for Toxoplasma gondii antibodies, by use of the modified agglutination test. Sixty percent (357/593) of the deer had T gondii antibodies; 10% had titer of 25, 23% had titer of 50, and 27% had titer greater than or equal to 500. Sex-specific differences in prevalence were not detected.

Cardiorespiratory effects of the combination of acepromazine maleate (ACP) and buprenorphine hydrochloride (BPN) were studied in 11 healthy, conscious dogs. Values for systemic and pulmonary artery blood pressure, cardiac output, arterial and venous pH and blood gas tensions, and invasive and noninvasive estimates of ventricular systolic function, preload, and afterload were obtained before sedation and after administration of each drug. Acepromazine maleate (0.1 mg/kg, IV) depressed cardiac function, compared with baseline values for unsedated dogs. Cardiac output decreased from a mean (+/- SD) value of 4.2 (+/- 1.5) L/min to 3.1 (+/- 0.8) L/min (P < 0.001), a change not attributed to heart rate. Pulmonary capillary wedge pressure decreased from 8.3 (+/- 4.2) mm of Hg to 6.5 (+/- 4.3) mm of Hg (P < 0.01), but mean right atrial pressure did not change. Left ventricular measurement of the maximal positive rate of pressure change (dP/dtmax) decreased from 2,668 (+/- 356)/mm of Hg/s to 2,145 (+/- 463) mm of Hg/s (P < 0.001), and ventricular stroke volume decreased from 43.2 (+/- 15.2) ml/beat to 32.3 (/- 8.6) ml/beat. Noninvasive indices of left ventricular function, ventricular shortening fraction, peak aortic velocity, and aortic average acceleration were decreased after ACP administration, but were not statistically different from baseline values. Mean systemic arterial blood pressure decreased from 121 +/- 12 mm of Hg to 96 +/- 13 mm of Hg 15 minutes after ACP administration (P < 0.001). Total systemic vascular resistance was not significantly different from the baseline value. Sequential administration of cumulative doses of BPN (0.005, 0.01, and 0.1 mg/kg of body weight, IV), initiated 15 minutes after administration of ACP, did not cause statistically significant depression of hemodynamic variables, except for heart rate, which decreased after BPN, and left ventricular dP/dtmax, which decreased slightly at the highest dose of BPN. Small, clinically insignificant changes in blood pH, venous bicarbonate concentration, and PaCO2 were observed after administration of ACP and BPN. Respiratory rate decreased from 60 +/- 48 breaths/min to 24 +/- 12 breaths/min, and sedation level was significantly (P < 0.05) increased from baseline values by administration of ACP. Sedation level was further increased by administration of BPN at the lowest dose (P < 0.05). The combination of ACP and BPN resulted in good to excellent sedation, but depressed ventricular function; however, most of the hemodynamic effects could be attributed to administration of ACP and withdrawal of sympathetic activity.

Objective: To examine the regional variations in the distribution of equine motor neuron disease (EMND) in the United States and the factors that might explain those variations. Design: Cluster investigation and case-control study. Sample population: The study population consisted of 97 horses with histopathologically confirmed EMND and 698 controls with diagnosis of other spinal cord disorders at 21 US veterinary teaching hospitals participating in the Veterinary Medical Data Base. Procedure: The total horse population of the United States was divided into 21 regions, and the regional incidence rates of EMND from January 1985 through January 1995 were estimated. Moran's index of spatial autocorrelation was calculated to test for spatial clustering of the disease. The 21 regions were then joined in broader areas according to the similarity of their EMND rates by means of the cluster analysis statistical technique. Finally, the role of potential confounding factors (age at diagnosis, month of diagnosis, breed, and sex) in the present distribution of EMND was assessed, using logistic regression analysis. Results: Differences in estimated rates across the 21 regions resulted in a strong pattern of spatial clustering of EMND in the United States. The geographic units were grouped into 5 risk regions, with the gradient of EMND incidence rates increasing from the western states (almost 0 cases/1,000,000 horse-years) toward New England (20.78 cases/1,000,000 horse-years). Reported risk factors of EMND (age, breed) and other extraneous factors (sex, month of diagnosis) could not explain the observed geographic variations of disease rates. Nevertheless, there is evidence of some confounding attributable to age and breed. Conclusions: Although the mechanism responsible for the clustering of EMND in northeastern states is still unexplained, it is not an epiphenomenon caused by regional differences in the distribution of the factors investigated.

Growing dogs were fed diets containing soy oil or poultry fat as the main fat source and soybean meal or meat meal as the main protein source to examine the effects of types of dietary fat and protein on fatty acid concentrations in serum and skin and on serum cholesterol concentrations. Dogs fed diets containing soy oil had higher serum linoleic acid concentrations and lower serum oleic acid, arachidonic acid, and cholesterol concentrations than dogs fed diets containing poultry fat. The type of dietary protein had marginal effects on fatty acid concentrations and did not affect serum cholesterol. Similar differences were found in cutaneous fatty acid concentrations, with soy oil-fed dogs having significantly (P < 0.05) higher linoleic acid and lower oleic acid concentrations in their skin than had poultry fat-fed dogs. This study suggested that dietary fat source influences serum and cutaneous fatty acid concentrations and serum cholesterol concentrations in dogs, irrespective of dietary protein source.

Urine activity product ratios of uric acid (APRua), sodium urate (APRna), and ammonium urate (APRau), and urinary excretion of 10 metabolites were determined in 24-hour urine samples produced by 6 healthy Beagles during periods of consumption of 4 diets containing approximately 11% protein (dry weight) and various protein sources: a 72% moisture, casein-based diet; a 10% moisture, egg-based diet; a 72% moisture, chicken-based diet; and a 71% moisture, chicken-based, liver-flavored diet. Significantly (P < 0.05) higher APRua, APRna, and APRau were observed when dogs consumed the egg-based diet, compared with the other 3 diets; there were no differences in these ratios among the other 3 diets. Twenty-four-hour urinary excretions of chloride, potassium, phosphorus, and oxalic acid were significantly (P < 0.05) higher when dogs consumed the egg-based diet. Twenty-four-hour urinary excretions of sodium were significantly (P < 0.05) higher when dogs consumed the egg-based diet, compared with the casein-based diet and the chicken-based, liver-flavored diet, but were not significantly different between the egg-based diet and chicken-based diet. Twenty-four-hour urine volume was similar when dogs consumed the 4 diets. Twenty-four-hour endogenous creatinine clearance was significantly (P < 0.05) lower when dogs consumed the casein-based diet; there were no differences among the other 3 diets. Although consumption of all diets was associated with production of alkaline urine, the 24-hour urine pH was significantly (P < 0.05) higher when dogs consumed the egg-based diet. These results suggest that use of diets containing approximately 10.5% protein (dry weight) and 70% moisture in protocols designed for dissolution and prevention of urate uroliths may be beneficial. The source of dietary protein in canned formulated diets does not appear to significantly influence the saturation of urine with uric acid, sodium urate, or ammonium urate.

Thirty-five heifers were allotted to 3 groups. Group 1 (contro]) consisted of 10 heifers that were not vaccinated and were challenge exposed by breeding to infected bulls. Group 7 (natural challenge exposure) consisted of 10 heifers that were vaccinated and challenge exposed by breeding to infected bulls. Group 3 (experimental challenge exposure) consisted of 15 heifers that were vaccinated and challenge exposed by breeding to infected bulls and by intravaginal inoculation with 10(7) Tritrichomonas foetus. Total immunoglobulin concentrations and specific trichomonal antibodies were determined in serum and vaginal secretions of heifers, using radial immunodiffusion and ELISA procedures. Control heifers remained infected for a mean of 10.6 weeks (range, 0 to 18 weeks), and heifers of the natural and experimental challenge-exposure groups remained infected for 3.2 and 5.0 weeks, respectively (range, 0 to 12 weeks). Total serum and cervicovaginal mucus concentrations of IgM, IgA, IgG1, and IgG2 did not change significantly after vaccination or challenge exposure. However, ELISA titers of total trichomonal antibodies increased up to 1:10,000 (range, 1:400 to 1:10,000) in serum after vaccination, and increased approximately tenfold above background in cervicovaginal mucus. In serum, the predominant trichomonal antibody isotype was IgG1, although trichomonal IgA and IgM antibodies also increased. The predominant trichomonal antibody detected in cervicovaginal mucus was IgA. Antibody titers in serum and cervicovaginal mucus of vaccinated heifers were not increased by infection. However, in control heifers, the total local trichomonal antibody response increased three- to fivefold after infection. In these heifers, specific antibodies in serum were predominantly IgG1 and local (cervicovaginal) antibodies were predominantly IgA.

In gas exchange studies addressing the storage and transport of CO2 in dogs, a model in which cardiac output (QT) can be precisely controlled and measured would be beneficial. We identified problems with described extracorporeal circuits and implemented right atrial bypass (RAB) in dogs. In 6 anesthetized (chloralose and urethane), heparinized dogs (mean +/- SD, 24 +/- 4 kg) with open thorax, cannulas were inserted in both vena cavas to drain venous blood return to a reservoir (anaerobic bag or bubble oxygenator). A roller pump then drove blood through a heat exchanger back to the right atrial appendage. After 1.8 +/- 1.4 hour of RAB, physiologic variables remained within reference limits for dogs (QT, 1.5 +/- 0.3 L/min; blood pressure, 92 +/- 25 mm of Hg; arterial P(CO2), 35 +/- 4 mm of Hg; P(O2), 513 +/- 39 mm of Hg; pH, 7.39 +/- 0.08; and tissue CO2 production, 126 +/- 56 ml/min). To permit study of gas exchange, venous return (and thus, QT) and venous P(CO2), and P(O2) could be accurately regulated and measured over a wide range. Maintenance of native pulsatile lung perfusion and cardiogenic oscillations minimizes mismatching of pulmonary ventilation and perfusion and facilitates studies addressing pulmonary gas exchange. This RAB model is designed so that investigators can establish the preparation in a few hours.

In 33 healthy dogs, 66 bronchoalveolar lavage samples from the right and left caudal lung lobes were analyzed for volume of return, cellularity, differential cellularity, and immunophenotypic lymphocyte subpopulations. Lavage return was 64.8% (mean) following 3 sequential 25-ml lavages, for a total lavage volume of 75 ml. With this technique, 21.1 X 10(6) cells/sample (mean) were obtained. The cellular components of bronchoalveolar lavage samples, in decreasing order of frequency, were alveolar macrophages (79.4%), lymphocytes (13.5%), eosinophils (3.6%), mast cells (2.1%), epithelial cells (0.8%), and neutrophils (0.6%). Mean alveolar lymphocyte subpopulation frequencies, determined in 18 samples, for pan T, CD4, and CD8 cells were 52, 21.9, and 17.8%, respectively, with a CD4/CD8 ratio of 1.3. Variables analyzed did not vary between right and left caudal lung lobes, nor were they affected by body weight.

We performed a study to determine a reference range for serum alpha 1-antitrypsin (alpha 1 AT) in dogs by specific immunoassay; to evaluate whether serum alpha 1 AT concentration varied with age, sex, or reproductive status in healthy dogs; and to investigate whether the serum alpha 1 AT concentration in hospitalized dogs differed from that of healthy, nonhospitalized dogs. Serum alpha 1 AT was quantitated by radial gel immunodiffusion for 60 healthy dogs and 311 hospitalized dogs. In healthy dogs, serum alpha 1 AT concentration was 2.33 +/- 0.41 mg/ml (mean +/- SD), yielding a reference range (mean +/- 2 SD) of 1.51 to 3.15 mg/ml. A correlation was not found between serum alpha 1 AT concentration and age in healthy dogs. The serum alpha 1 AT concentration (mean +/- SEM mg/ml) was significantly higher in healthy, sexually intact females (2.64 +/- 0.1) than in healthy, spayed females (2.22 +/- 0.12; P < 0.004); healthy, sexually intact males (2.14 +/- 0.1; P < 0.0006); and healthy, castrated males (2.25 +/- 0.14; P < 0.02). Hospitalized, sexually intact females had a lower serum alpha 1 AT concentration (1.93 +/- 0.07) than healthy, sexually intact females (2.64 +/- 0.1; P < 0.0002). Likewise, the serum alpha 1 AT concentration in hospitalized, sexually intact males (1.92 +/- 0.04) was less than in healthy, sexually intact males (2.14 +/- 0.1; P < 0.04). A difference in alpha 1 AT concentration was not found between healthy and hospitalized, neutered dogs.

Owing to technical and ethical limitations, a substantial part of the knowledge about the pathophysiologic mechanism of the human diaphragm has been obtained from studies in which phrenic nerve activation was usually carried out by direct surgical exposure of the nerves in the neck of deeply anesthetized, mechanically ventilated animals. Novel information has been gleaned from such studies, but the restrictive conditions under which it was collected preclude reliable extrapolation. We, therefore, addressed the question of whether accurate electrophysiologic evaluation of the phrenic nerve-diaphragm pathway can be performed in intact, nonanesthetized calves. Transjugular phrenic activation was well tolerated, safe, specific, and able to achieve constant symmetric and supramaximal phrenic stimulations during prolonged periods. Eighteen noninvasive cutaneous and esophageal reception circuits were tested for their ability to record the diaphragmatic evoked potential. In addition, they were compared for specificity and reproducibility of the recorded potentials during prolonged periods of tidal or stimulated respiration. The best diaphragmatic potential was recorded from surface electrodes attached to the skin of the ninth and tenth intercostal spaces, using a xyphoidian reference. We describe a method that allows easy, long-term, and reliable electrophysiologic evaluation of the phrenic nerve-diaphragm pathway in intact, conscious calves. It is hoped that such a model will produce relevant novel information regarding pathophysiology of the diaphragm.