Immunoglobulin E is produced in response to parasitic nematodes that undergo blood and tissue migrations. Results of our previous studies indicated that IgE and IgG respond to Dirofilaria immitis in experimentally infected dogs. To determine the association between treatment with the larvicide, diethylcarbamazine (DEC), and antibody responses and to examine the potential influence of infection with a nonfilarid intestinal nematode on isotype-specific immune responses, we monitored, by use of isotype-specific ELISA, separate IgE and IgG responses against D immitis in 4 groups (A-D) of 8 dogs experimentally coinfected with D immitis and Ancylostoma caninum. All dogs were monitored from 2 weeks before inoculation with D immitis, through postinoculation (PI) week 20. Group-B dogs received a daily regimen of 6.6 mg of DEC/kg of body weight. Group-C dogs received 4.95 mg of oxibendazole/kg daily. Group-D dogs received DEC and oxibendazole, equivalent to the daily doses given to dogs of groups B and C. All dogs given oxibendazole had no A caninum at necropsy. Of the groups receiving DEC, 3 group-B dogs each had 1 to 2 D immitis at necropsy. When results of chronologic IgE determination for all groups were statistically compared, only groups B and C had significant (P = 0.0148 and P << 0.00005, respectively) increases in IgE values. Group-C dogs had the highest IgE values from PI week 10 until the end of the study, whereas IgG values were statistically identical to those of group-A dogs. Group-B dogs given only DEC and having the least number of D immitis of all groups, had IgE values that peaked at PI week 6; values were significantly (P = 0.0002) higher than those for all other groups. In Group-B dogs, IgG values increased significantly (P << 0.00005) only at PI week 20 and were significantly (P << 0.00005) decreased after PI week 6, compared with values for all other groups. Group D containing 6 dogs infected with 1 to 18 D immitis found at necropsy had IgE values between those of group-B dogs and those of non-DEC-treated groups at PI week 6. There was no difference in IgG values between 3 groups at PI week 6, and IgE values were found to be a better correlator than were IgG values to the number of D immitis larvae killed in the tissues during this period. All differences in IgG and IgE values not only correlated with treatment status and number of D immitis adults found at necropsy, but also with the developmental stage of D immitis commonly present in the groups at each time point and the number of adult D immitis found at necropsy.

A field trial was conducted on a commercial swine farm quarantined because of infection with pseudorabies virus. The purpose was to investigate, in growing pigs born to hyperimmunized sows, the immunogenicity of a vaccine with a glycoprotein I (gE) deletion. One hundred twenty pigs were assigned at random to 1 of 3 vaccination schedules at ages: 8 and 12 weeks; 8, 12, and 14 weeks; and 8, 12, and 16 weeks. Immune response was measured at 8, 12, 14, 16, and 18 weeks, using the serum neutralization test, a screening ELISA, and assays of IgG and IgA in serum and nasal secretions. Results of the serum neutralization test and the screening ELISA indicated that, for pigs vaccinated only at 8 and 12 weeks, the percentage of pigs with pseudorabies virus serum antibodies decreased substantially by 18 weeks; for pigs given a booster at 14 or 16 weeks, the prevalence of serum antibodies at 18 weeks was higher, with 16-week booster vaccination eliciting the best response. At each age, nasal IgA and IgG values were highly correlated (r greater than or equal to 0.70), as were serum IgA and IgG values; correlations of serum with nasal IgA and IgG values were somewhat lower (approx range, r = 0.40 to 0.70). Nevertheless, an increase in serum IgA or IgG values on vaccination was no guarantee of an increase in nasal IgA or IgG values. For serum and nasal mucosal antibodies, a poor immune response was associated with high quantities of maternally derived antibodies. Vaccination at 16 weeks was necessary to ensure eliciting of an immune response in almost all pigs.

Objective--To measure arterial and venous blood gas, coagulation, and fibrinolysis variables in blood from isolated segments of control and ischemic large colons for the purpose of identifying variables for rapid, indirect assessment of colonic mucosal injury. Design--Variables were determined at specific intervals during the 4-hour study (3 hours of ischemia and 1 hour of reperfusion). Animals--Seven clinically normal horses between 2 and 15 years old. Procedure--Horses underwent laparotomy and occlusion of the lumen and vasculature of the mid-portion of the pelvic flexure of the large colon. During ischemia of 1 randomly-chosen colonic segment, variables were measured to determine colonic mucosal damage and were compared with histologic scores of colonic biopsy specimens. Results--Significant (P < 0.05) differences from control values were observed over time for venous pH, Pco2, PO2, oxygen saturation, oxygen content, arteriovenous oxygen difference, and lactate and glucose concentrations. Mean histologic scores of biopsy specimens obtained from ischemic colons were significantly (P < 0.05) greater (indicating greater damage) than those from control colons, and increased significantly (P < 0.05) with duration of ischemia. Conclusions--Venous lactate, oxygen saturation, and PO2 values were the most significant predictors of the severity of histologic damage within the ischemic colons (R2 = 0.661). Clinical Relevance-Venous blood gas and lactate values in the large colon are good predictors of the amount of intestinal damage incurred during 3 hours of ischemia, and may be clinically useful for the rapid determination of colonic viability.

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.

Neospora caninum-induced abortion is a major production problem in the daily cattle industry in the United States and worldwide. Abortions attributable to naturally acquired N caninum infection also have been observed in pygmy goats. We studied experimentally induced infections with N caninum in pregnant pygmy does to determine whether abortions attributable to N caninum infection would occur after inoculation. Seven pregnant pygmy does (1 control doe and 6 inoculated with N caninum) were studied. The control doe remained clinically normal throughout the study and delivered 2 healthy kids. Abortion, fetal death, and stillbirths were observed in some pregnant does inoculated with N caninum. Two pregnant pygmy does inoculated with N caninum early in gestation (day 51) had fetuses that died and were aborted, or died and were reabsorbed. Neospora caninum tachyzoites and lesions were observed in the brain, spinal cord, and heart of aborted fetuses; parasites also were isolated from the placenta. Four additional pregnant pygmy does (2 inoculated at mid-gestation [day 85], and 2 at late gestation [day 127]) did not abort after inoculation. However, 1 doe inoculated during mid-gestation delivered a stillborn fetus that had died about 1 week prior to parturition. This kid was congenitally infected with N caninum. Neospora caninum was isolated from the placentas of all inoculated does examined. Neonatal neosporosis was not observed in live-born kids, nor were stages of N caninum isolated from any live-born kid. Does did not undergo abortion or have congenitally infected kids when they were rebred and evaluated for neosporosis.

Objective--To study whether end products of 2 pathways of anaerobic energy metabolism, lactate and purines, that accumulate in the blood after intense exercise indicate any relation to exercise performance. Design--Venous blood samples were taken within 1 and 15 minutes after a trotting race of 2,100 m. Animals--16 Clinically healthy Standardbred trotters. Procedure--Blood and plasma lactate concentrations were measured by enzymatic analyzer, and purines, uric acid and allantoin, were determined by high-performance liquid chromatography. The concentrations of metabolites were then correlated to racing time and individual performance indexes that are annually calculated from the percentage of winnings, placings, and starts rejected, average earnings per start, and the racing record. Results--Blood lactate concentration immediately and calculated cell lactate concentration immediately and 15 minutes after the race correlated positively (P < 0.05 to P < 0.01) with the individual performance indexes. Plasma lactate concentration was not correlated to the individual performance indexes. Uric acid concentration, immediately and 15 minutes after the race, was negatively correlated (P < 0.05) to the individual performance indexes, and a positive relation (P < 0.05) was found between the highest concentration of uric acid and the racing time. Concentration of allantoin immediately or 15 minutes after the race did not have any significant correlation to the individual performance indexes. Conclusions--Accumulation of lactate in the blood, which was greater in the superior performing horses, may prove to be an useful predictor of anaerobic capacity. The results also indicate that the loss of purine nucleotides was less in the superior performing horses, although further studies are needed to confirm this.

A nested polymerase chain reaction (PCR) test was developed to examine infection with the bovine lentivirus, bovine immunodeficiency-like virus (BIV), in cattle. Primers were designed to amplify 2 separate regions of the pol and env segments of the BIV genome. Two calves were experimentally infected with an isolate derived from the original strain of BIV, R29, or with a recent field isolate, FL491. Serial blood samples were collected and examined by virus isolation, protein immunoblot, and nested PCR. The nested PCR test detected BIV infection by 3 days after inoculation, earlier than the other 2 methods, and continued to identify infected cattle 9 to 15.5 months after inoculation, even when results from virus isolation and serology became negative. Nested PCR also detected multiple-size env products in samples obtained later in the infection from the calf that received FL491, giving evidence that viral quasispecies were selected during in vivo replication of the virus. Results indicated that the nested PCR test is more sensitive than virus isolation or serology for the detection of BIV infection in cattle.

Whereas the clinical efficacy of vaccination against pseudorabies has been studied extensively, methods to evaluate the influence of vaccination on pseudorabies virus (PRV) transmission have only recently become available. In this study, PRV transmission and growth performance in finishing pigs vaccinated either once or twice were compared. The incidence of PRV infections was significantly (P = 0.039) higher in the group vaccinated once (38%) than in the group vaccinated twice (10%). The reproduction ratio R, which is defined as the average number of new infections caused by 1 infectious individual, was estimated in both groups. This ratio was also significantly (P = 0.025) higher among single vaccinated pigs (R = 3.4) than among pigs that had received double vaccination (R = 1.5). In compartments where serologic evidence of PRV introduction was observed, the mean daily weight gain was significantly (P = 0.029) lower in pigs vaccinated once (698 g/d) than in pigs vaccinated twice (721 g/d). Results of this study document the possibility to objectively evaluate the effect of vaccination on PRV transmission under field conditions. From the results, we concluded that double vaccination is advantageous in populations of finishing pigs at risk for PRV introduction. However, even among pigs vaccinated twice, extensive spread of PRV can occur.

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.