To examine the postnatal development of equine small intestine, biopsy specimens of jejunal mucosa from 8 ponies, between 6 and 28 weeks old, were subjected to analytical subcellular fractionation and assay of organelle marker enzymes. Fractionation revealed a reduction in the particulate brush border component of beta-galactosidase (lactase) activity between 6 and 28 weeks, and a corresponding increase in soluble activity, although the reduction in mean specific activity was not significant. There also was a decrease in the proportion of brush border to soluble aminopeptidase N activity, a relative loss of brush border gamma-glutamyltransferase activity, and a considerable decrease in the specific activity of alkaline phosphatase throughout the gradient fractions. In contrast, there were marked increases in activities of (alpha-glucosidase (maltase) and sucrase in the older ponies, accompanied by considerable changes in the intracellular distribution of particulate alpha-glucosidase activity, which was predominantly associated with endoplasmic reticulum at 6 weeks, whereas the large increase in activity observed by 28 weeks was clearly associated with the brush border. The modal density of brush borders also increased with age, suggestive of an increase in the glycoprotein-to-lipid ratio of the microvillar membrane. In contrast to these brush border changes, there was relatively little alteration in the activities or density distributions of marker enzymes for endoplasmic reticulum, basolateral membranes, mitochondria, or lysosomes. These findings indicate that maturation of equine intestinal epithelium during the first few months of life results in major changes in the properties and enzyme composition of enterocyte brush borders.

Trypanosomiasis has been reported in dogs from Texas, Oklahoma, Louisiana, and South Carolina. We describe the first isolation and characterization of Trypanosoma cruzi from a Walker Hound pup in Virginia that also had postvaccinal distemper. The mother of the pup and 7 of its 8 siblings also were found to be infected with T cruzi, suggesting that the parasite had been transmitted transplacentally or through lactation. Parasitologic, serologic, histologic, and molecular methods were used to establish the diagnosis of T cruzi infection in these dogs. In a serologic survey of 12 dogs (including the sire of the pups) from the area in which the index case occurred, none were found to have antibodies to T cruzi. However, 2 of a further 52 dogs from different areas (to the index case), but in the same county, were sero-positive to T cruzi. These findings indicate that canine trypanosomiasis is present in an area of the United States not previously known to be enzootic.

We defined methods for use of luminol-dependent chemiluminescence (LDCL) and superoxide anion (O2-) production as parameters of the oxidative metabolism of neutrophils isolated from 1.5- to 5-week-old neonatal calves. We determined how variations in blood sample handling, agonist preparation, individual variability, and age of calves influenced the LDCL and O2- responses to certain agonists, and defined concentrations of soluble and particulate agonists that maximally stimulated the oxidative metabolism of bovine neutrophils. Oxidative responses, particularly LDCL, were characterized by marked dayto-day variability, differed greatly within and between calves, were partially age-dependent, and were partially dependent on the individual agonist. Superoxide anion production had substantially less variability. We compared the in vitro oxidative (LDCL and O2-) responses of neutrophils isolated from neonatal calves stimulated by defined concentrations of the agonists-latex, phorbol myristate acetate, calcium ionophore, and opsonized zymosan-with responses to formylated oligopeptides and zymosan-activated serum, and to live, dead, live opsonized, and dead opsonized Pasteurella haemolytica organisms. Opsonization of particulates, pathogenic or nonpathogenic, enhanced the LDCL and O2- responses of stimulated neutrophils although P haemolytica was a less potent stimulant of oxidative functions than were nonbiological agonists. We conclude that the generation of reactive oxygen species by bovine neutrophils in response to P haemolytica is highly dependent on the presence of opsonins and is greatly enhanced in live vs killed bacteria. Futhermore, the in vitro generation of reactive oxygen species, including O2- by stimulated neutrophils, may be of biologic importance if similar events occur in vivo, and could have a major role in the pathogenesis of the acute lung injury associated with pneumonic pasteurellosis.

We generated monoclonal antibodies (MAB) against feline immunodeficiency virus (FIV) and characterized these MAB by single competition enzyme immunoassays (EIA), immunoblot analysis, and radioimmunoprecipitation. Four MAB identified 3 distinct epitopes of the FIV p24/26 gag major core protein. One MAB recognized the p16/17 gag protein none recognized envelope proteins. We developed an FIV p26 antigen capture EIA that proved more sensitive (0.5 ng of p26/ml), less expensive, and less time-consuming than reverse transcriptase assay. The same MAB were used to develop an antibody EIA specific for FIV p26. The MAB and capture assays reported should prove useful in FIV diagnosis and research.

An ELISA was developed to determine serum concentration of apolipoprotein B-100, a major triglyceride-binding protein in very low-density lipoproteins and a putative maker for hepatic lipidosis of dairy cows. Serum apolipoprotein B-100 was prepared electrophoretically, and antibodies to this protein were raised in rabbits. The antiserum prepared was further purified by affinity chromatography, using bovine serum albumin-Sepharose 4B, to remove antibodies to albumin. For the ELISA, addition of 2-mercaptoethanol to the coating buffer (50 mM sodium carbonate, pH 9.6) was required to evaluate apolipoprotein B-100 concentration in serum. The ELISA developed was sensitive (detection limit was 300 to 400 ng/ml of serum) and reliable (coefficients of variance were in the range of 3.3 to 7.6%). By use of the established ELISA, the serum apolipoprotein B-100 concentration was found to be significantly (P < 0.01) lower during the early lactating stage than during other stages of lactation. Reduced hepatic synthesis or secretion of apolipoprotein B-100 during the early lactating stage, together with the excess uptake by the liver of serum nonesterified fatty acids, is suggested to be relevant in the accelerated accumulation of triglycerides in the liver of dairy cows during the periparturient period.

In Zimbabwe, ocular squamous cell carcinoma (OSCC) was frequently observed in 5 breeding herds of Simmental cattle, a Bos taurus breed originating from Switzerland. In these herds, initial signs of OSCC were already noticeable in cattle about 3 years old. Gradually, OSCC prevalence increased, and 36 to 53% of cattle over 7 years old had 1 or more tumors. More tumors developed in Simmental cattle with periorbital white skin than in cattle with periorbital pigmented skin. Other breeds of cattle (eg, Friesian) also are partly white-faced and live in Zimbabwe in a comparable environment; yet, OSCC prevalence was lower in those breeds.

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.

Investigation of the structure of equine articular cartilage link protein (LP) from individuals ranging in age from 1 to 15 years identified 3 distinct isoforms having molecular weights of 46,000, 43,000, and 41,000. The relative amounts of each of the 3 isoforms altered with age. The largest form did not change with age; however, amounts of the Mr 43,000 and 41,000 forms increased with increasing age. The results suggested that an accumulation, in the extracellular matrix of cartilage, of these 2 smaller products may have arisen from proteolytic cleavage. The complete amino acid sequence of the protein core was determined from complementary DNA products prepared by polymerase chain reaction amplification of cartilage LP mRNA. The sequence had 96% similarity with human LP and with that of other species for which the primary structure has been determined. This high degree of sequence conservation and the isoform data indicate that extracellular processing of LP occurs by similar mechanisms in various species. At the transcription level, equine chondrocytes were found to express LP as 2 abundant mRNA of 5.0 and 3.0 kb, and a smaller mRNA of 1.5 kb. Processing of the LP mRNA in horses, thus, appears to be similar to that found in other species investigated, and although multiple transcripts are present, the coding region remains unaltered and only 1 protein product is made.

Hyperxanthinuria and xanthine uroliths have been recognized with increased frequency in dogs with ammonium urate uroliths that had been given allopurinol. We hypothesized that dietary modification might reduce the magnitude of uric acid and xanthine excretion in urine of dogs given allopurinol. To test this hypothesis, excretion of metabolites, volume, and pH were determined in 24-hour urine samples produced by 6 healthy Beagles during periods of allopurinol administration (15 mg/kg of body weight, PO, q 12 h) and consumption of 2 special purpose diets: a 10.4% protein (dry matter), casein-based diet and a 31.4% protein (dry matter), meat-based diet. Significantly lower values of uric acid (P = 0.004), xanthine (P = 0.003), ammonia (P = 0.0002), net acid (P = 0.0001), titratable acid (P = 0.0002), and creatinine (P = 0.01) excreted during a 24-hour period were detected when dogs consumed the casein-based diet and were given allopurinol, compared with the 24-hour period when the same dogs consumed the meat-based diet and were given allopurinol. For the same 24-hour period, urine pH values, urine volumes, and urine bicarbonate values were significantly (P = 0.0004, P = 0.04, and P = 0.002, respectively) higher during the period when the dogs were fed the casein-based diet and given allopurinol than when they were fed the meat-based diet and given allopurinol. Endogenous creatinine clearance was significantly (P = 0.006) lower when dogs were fed the casein-based diet and given allopurinol than when they were fed the meat-based diet and given allopurinol. Significantly lower concentrations of plasma uric acid (P = 0.0001), plasma xanthine (P = 0.01), and serum urea nitrogen (P = 0.0001) were detected when dogs consumed the casen-based diet and were given allopurinol than when they consumed the meat-based diet and were given allopurinol. On the basis of these results, use of the casein-based diet and allopurinol in protocols designed for dissolution of urate uroliths may be beneficial in preventing hyperxanthinuria and xanthine urolith formation.

A rapid subjective method for estimating the extent of gross pneumonia lesions in slaughtered pigs was compared with dissection of lungs in 51 slaughtered pigs. After standardization for prevalence in the regional industry, regression analysis indicated that the subjective method was highly predictive of the extent of pneumonic lesions (R2 = 0.88). Part of the error with the subjective method was attributed to approximations used for the relative proportions of lung lobes, which result in overestimation of the affected tissue by approximately 90%. Retrospective analysis of data from a slaughter monitoring program revealed strong associations (R2, 0.54 to 0.91) between prevalence, mean, median, and maximal lung scores in groups of pigs. Maximal lung score was biased by sample size, but prevalence and mean or median lung scores could be used to describe pneumonia severity in groups of pigs. Our results indicate that error in measurement of the extent of pneunomic tissue in slaughtered pigs is unimportant if the time of onset, clinical severity, and duration of disease are not quantified.