A virologic survey was conducted on calves with diarrhea associated with bovine rotavirus (BRV) on a closed dairy farm. The BRV was detected from 32 of 219 (14.6%) fecal specimens repeatedly collected from 56 calves born during the years 1992-1993, regardless of whether they had diarrhea. Most of the 32 strains were isolated from fecal specimens obtained from 2-to 6-week-old calves. After electrophoresis of doublestranded viral RNA from the 32 strains, genomic RNA migration patterns were similar to those of the predominant BRV strains isolated at the same farm during the years 1990-1991. All representative strains were identified as G serotype 6 (G6) and P type 5 (P5) by results of the virus-neutralization test and polymerase chain reaction procedure. Thus, BRV had no change in genomic RNA electropherotypes and serologic antigenicities in a closed dairy herd over a period of several years.

Reference values for hematologic variables change with increasing age in cattle. Therefore, the purpose of the study reported here was to describe the peritoneal fluid constitutents of clinically normal young calves, and to compare cellular concentration and distribution in blood and peritoneal fluid of young calves with those of adult cattle. Eight healthy 8-week-old male Holstein calves and 8 healthy 3- to 8-year-old Holstein cows were studied. Peritoneal fluid was collected from calves along the ventral midline, 4-cm cranial to the umbilicus. Abdominocentesis was performed in the region of the lower right flank in adult cattle. Correlation analysis, using the Pearson's correlation coefficient, and regression analysis were performed for blood and peritoneal fluid data from calves. Data from calves were compared with those of cows, using Wilcoxon's rank sum test. A P value < 0.05 was considered significant for all tests. Calves had significantly lower blood eosinophil count (P < 0.003) and plasma protein concentration (P < 0.001) than did cows. Calves had significantly higher peritoneal fluid nucleated cell (P < 0.05) and mononuclear cell (P < 0.05) counts, but lower peritoneal fluid eosinophil cell count (P < 0.003) than did cows. For calves, nulceated cell and lyhocyte cell counts in the blood had a high, positive correlation with those of peritoneal fluid. However, the prediction equation for nucleated cell count accounted for a modest proportion of variability. A prediction equation for peritoneal fluid lymphocyte cell count was established. On the basis of results of this study, reference ranges established for peritoneal fluid constituents of clinically normal adult cattle may not be appropriate for interpretation of peritoneal fluid analysis of calves.

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.

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.

To measure the concentration of serum amyloid A (SAA) protein in horses a sensitive and highly reproducible sandwich (ELISA) was established, using affinity purified SAA antibody. Results of the ELISA were found to have a high correlation (r = 0.95) with those of the single radial immunodiffusion test. Equine SAA concentration was measured by use of this ELISA. In clinically normal horses, the concentration of SAA was high immediately after birth to 2 weeks of age. After that, SAA concentration had periodic fluctuations in the range of approximately 10 to 30 microgram/ml. Mean (+/- SD) concentrations of SAA in foals (less than or equal to 12 months old) and adult horses (greater than or equal to 18 months old) were 21.23 +/- 12.20 and 14.93 +/- 9.07 microgram/ml, respectively. In mares during the perinatal period, SAA concentration remained stable within the reference range before parturition. It increased quickly after delivery, and reached a peak value of 101.29 +/- 98.82 microgram/ml on postpartum day 3, then began to decrease, at postpartum week 2, to the reference range by the end of postpartum month 1. In horses with experimentally induced inflammation, SAA concentration increased quickly and reached approximately four- to 40-fold increase over the pretreatment value on day 1 and remained high on days 2 to h after treatment. It then returned to the baseline value by 2 to 4 weeks in association with disappearance of local signs of inflammation. The SAA concentration was high in most horses with clinical signs of inflammation. It was concluded from these data that this ELISA is sensitive and reliable for measuring SAA in horses.

Using an applanation tonometer, 5 replicate intraocular pressure (IOP) measurements were obtained from each eye of 12 young, clinically normal, American alligators. Alligator length ranged from 46 to 117 cm, measured from snout to tail tip. All IOP were recorded by a single observer at an ambient temperature of approximately 25 C, and ranged from 5 to 35 mm of Hg. Observer reliability was excellent (intraclass r = 0.93), and IOP did not change over the ordered sequence of 5 replicate measurements/eye. Replicate IOP measurements were, therefore, averaged in each eve for comparison between eyes of the same alligator. Left and right eye IOP were highly correlated within individual alligators (r = 0.92), whereas the mean within-animal difference between left and right eye IOP was not statistically significant (95% confidence interval [CI] for the left eye-right eye mean difference, -1.9 to 1.5 mm of Hg). Mean IOP determined for 5 confirmed females and 3 confirmed males did not differ significantly between the sexes (95% CI for the male-female difference in means, -2.1 to 3.7 mm of Hg). Mean +/- SEM IOP of 23.7 + 2.1 mm of Hg determined for 4 alligators < 50 cm long was significantly (P = 0.009) greater than mean IOP of 11.6 + 0.5 mm of Hg determined for 8 alligators > 50 cm long (95% CI for the difference in means, 8.5 to 15.7 mm of Hg). In young alligators, the relation between body length and IOP appears to be nonlinear, possibly with a negative exponent.

The metabolic responses of equine articular cartilage to incubation with bacterial lipopolysaccharide (LPS) were studied, using explant cultures of articular cartilage obtained from the metatarsophalangeal joints of 15 horses, age of which ranged from 3 months to 20 years. For comparison, explants were also established from the metatarsophalangeal joints of 3 calves. Explants were cultured for 3 days in medium containing various concentrations of LPS from 0 (control) to 100 microgram/ml. Glycosaminoglycan (GAG) released during the 3-day incubation was determined by a spectrophotometric assay, using the dye 1,9-dimethylmethylene blue. Newly synthesized GAG content was assayed by measuring [35S]sulfate incorporation during a 3-hour pulse labeling period. In addition, prostaglandin E2 (PGE2) synthesis was quantified, using a [3H]PGE2 radioimmunoassay kit and magnetic separation. Finally, explants from 3 animals were used to evaluate the effect of supplementing culture medium with 5% serum on the response of explants to LPS, and explants from 1 horse were used to compare responses to stimulation with LPS derived from 2 bacterial sources. Equine explants cultured with bacterial LPS had a dose-dependent decrease in synthesis and increase in release of GAG, and these responses were significantly (P < 0.0001) greater in explants from younger horses. In addition, equine explants had a significant (P = 0.0001) dose-dependent increase in concentration of PGE2 released into the culture medium in response to incubation with LPS. Comparison of data for GAG synthesis from equine and bovine explants revealed a significant (P = 0.025) difference in responsiveness to LPS between the 2 species. Equine explants tended to have a greater suppression of GAG synthesis in response to incubation with increasing concentrations of LPS than did age-corrected bovine samples. However, similar analysis of data on GAG release did not indicate any difference in sensitivity between the 2 species for this response. There was no evidence that the presence or absence of serum supplementation or the use of LPS derived from different bacterial sources made a significant difference in the response of explants to incubation with LPS.

To determine the effects of age on each analyte, CSF variables were evaluated in healthy foals from birth through 42 days of age. Cerebrospinal fluid was collected from 14 clinically normal, naturally delivered cross-bred foals and was analyzed for glucose, sodium, potassium, magnesium, and total protein concentrations, total and differential WBC counts, RbC count, and lactate dehydrogenase, aspartate transaminase, and creatine kinase activities. Samples were collected in 3 foals < 48 hours old, and at 11 to 14 days of age in 4 foals, 21 to 22 days of age in 3 foals, and 31 to 42 days of age in 4 foals. Each foal was tested only once, to avoid any effects of CSF sample collection on subsequent analysis. Regression analysis confirmed age-related effects on CSF glucose, protein, and magnesium concentrations, but did not indicate an effect of age on CSF sodium and potassium concentrations or cell counts. Results indicate that CSF glucose concentration decreases with age; foals < 2 days old had the highest CSF glucose values, 98.8 +/- 12.0 mg/dl (mean +/- 1 SD). In foals 10 to 14 days old, CSF glucose concentration was 67.3 +/- 12.0 mg/ dl, was 65.3 +/- 4.5 mg/dl in foals 21 to 22 days old, was 70.0 +/- 5.4 mg/dl in foals 31 to 42 days old, and was 51.1 +/- 2.5 mg/dl in adults. Protein values in CSF also decreased with age: 109.0 +/- 9.7 mg/dl in foals < 2 days old, 81.0 +/- 22.8 mg/dl in foals 10 to 14 days old, 60.5 +/- 22.4 mg/dl in foals 21 to 22 days old, and 58.5 +/- 17.0 mg/di in foals 31 to 42 days old. The CSF protein concentration was 60.3 +/- 10.8 mg/dl in adult horses. Magnesium concentration in CSF increased slightly with age, then decreased after 22 days of life. In foals < 2 days old, the value was 2.43 +/- 0.16 mg/dl. Values in older foals and horses were: 2.51 +/- 0.08 mg/dl in foals 10 to 14 days old, 2.65 +/- 0.05 mg/dl in 21- to 22-day-old foals, 2.55 +/- 0.05 mg/dl in 31- to 42-day-old foals, and 2.35 +/- 0.09 mg/dl in adult horses. Mean CSF sodium and potassium concentrations were 151.7 +/- 3.7 mmol/L and 3.14 +/- 0.54 mmol/L, respectively, for all ages. There was no effect of age on these analytes. Values for CSF enzymes were considered invalid for the assay technique used and were not further analyzed.

Biplanar radiography was used to study normal growth of the left and right radius in 5 Beagles and growth of the left radius alone in 15 additional Beagles. We explored the applicability of this radiographic method in veterinary medicine by measuring the contribution to total radius length from each growth plate. Spherical tantalum markers (0.5 mm) were embedded in the proximal epiphysis, diaphysis, and distal epiphysis of each dog's radius at 10 weeks of age. Simultaneous biplanar radiographic views were obtained every 4 weeks until skeletal maturity was documented. A three-dimensional coordinate system was constructed allowing for measurement of growth (in millimeters). Resolution of the measuring system was 0.074 mm. Mean +/- SEM length of the skeletally mature Beagle's radius, as measured from proximal epiphyseal bead to distal epiphyseal bead, was 95.33 +/- 1.07 mm. The percentage of contribution to the total radius length from the proximal and distal growth plates was 36.76 and 64.73%, respectively, with 95% confidence interval of 2.29%. The percentage of contribution to radius length from the distal radial growth plate increased for each consecutive time segment, with the distal radial physis contributing 61.75% from 10 to 14 weeks of age and increasing to 70.22% from 22 to 26 weeks of age. Significant growth was not observed after 26 weeks of age. The period of most rapid growth was between 10 and 14 weeks of age. Biplanar radiography was accurate and precise in quantifying the relative contribution of the proximal and distal growth plate to radius length in Beagles. The method is applicable in veterinary research or clinical medicine for monitoring of axial and angular growth: physiologic, iatrogenic, or pathologic.

Age-related changes in skin color and histologic features of hairless descendants of Mexican Hairless dogs were investigated and compared with those of haired descendants of Mexican Hairless dogs and Beagles. According to age, dogs studied were allotted to 4 groups: 0 to 2 weeks, 4 to 5 months, 1 to 1.5 years, and 3 to 4 years old. Skin color, histologic features, and numbers of dihydroxyphenylalanine (DOPA)-positive melanocytes were examined. The luminance values measured, using a spectrophotometer, decreased with advancing age up to 1.5 years, but they increased again at 3 to 4 years in hairless dogs. The number of DOPA-positive melanocytes in hairless dogs decreased with advancing age, whereas there were no DOPA-positive melanocytes in haired dogs and Beagles. Histologically, the epidermis of newborn hairless pups was thick. The border between the epidermis and dermis was wavy, and epidermal ingrowths were found projecting into the dermis. As hairless dogs grew older, the epidermis became thinner and flatter. Although numbers of hair follicles and sebaceous and apocrine sweat glands were apparently fewer in hairless dogs than in haired dogs and Beagles, these structures were detected at least up to 4 years of age. On the other hand, haired dogs and Beagles had a thin epidermis at birth and aging had little effect on their epidermal structures. The dermis of hairless dogs contained fewer mast cells than did that of haired dogs and Beagles.