In 8 Holstein cows, 50 colony-forming units (CFU) Of Escherichia coli was administered into 1 mammary gland. Infections were established in all inoculated glands. In 4 of the 8 cows, 500 mg of gentamicin sulfate was administered by intramammary infusion 14 hours after inoculation; the other 4 cows were untreated controls. Infusions of gentamicin also were given after each of the 3 successive milkings after the initial infusion, so that a total dose of 2 g of gentamicin was given to each of the treated cows. During the 33-hour treatment period and for the first milking after the last infusion of gentamicin, the treated cows had a mean gentamicin concentration of greater than or equal to 31.0 microgram/ml in milk samples that were collected from inoculated quarters immediately before each milking. Concentrations of 0.34 and 0.69 microgram of gentamicin were detected in milk from 2 cows at 8 days after inoculation with E coli. Mean serum concentrations of gentamicin were > 0.37 microgram/ml throughout the treatment period and the first 12 hours after the last infusion, with a mean peak concentration of 0.96 microgram/ml at 24.4 hours. The range of peak concentration of gentamicin detected in urine from all treated cows was 42 to 74.4 microgram/ml. Peak concentration of E coli in milk in the treated cows (6.08 +/- 1.02 log10 CFU/ml) did not significantly (P > 0.05) differ from that of the control cows (5.26 +/- 1.00 log10 CFU/ml). Similarly, mean duration of infection in the treated cows (54 hours) did not differ significantly from that of the control cows (48 hours). The treatment groups also did not differ significantly in peak concentrations of albumin or IgG1 in milk, although mean concentrations of albumin and IgG1 at 16 hours after inoculation, and of albumin at 20 hours, was significantly (P < 0.05) higher in the milk from control cows than from the treated cows. Mean values of peak rectal temperature and of mean rectal temperature throughout the trial did not differ between the groups. At the end of the 4-week trial, 1 of 4 inoculated glands in treated cows and 3 of 4 in control cows had somatic cell counts less than or equal to preinoculation concentrations (5.18 log10 cells/ml). Intramammary administration of gentamicin did not affect the duration or severity of experimentally induced E coli mastitis. In addition, substantial concentrations of gentamicin were detected in the serum of treated cows, suggesting that intramammary treatment may result in prolonged drug residues in tissue.

Cerebrospinal fluid samples from 2 groups of clinically normal dogs were compared after iopamidol (n = 9) and metrizamide (n = 8) myelography. Iopamidol (200 mg of I/ml) and metrizamide (170 mg of I/ml) were administered by cerebellomedullary injection at dosage of 0.45 ml/kg of body weight. In dogs of both groups, postmyelographic CSF changes included high specific gravity, Pandy score, protein concentration, and WBC count. The high specific gravity and Pandy score were false-positive effects attributed to nonionic contrast media. Although postmyelographic protein concentration and total WBC count were greater in CSF samples from dogs given metrizamide than in those given iopamidol, differences were not statistically significant. The differential WBC counts were consistent with mild, acute leptomeningitis; these findings were supported by results of histologic examination. Iopamidol and metrizamide should be considered low-grade leptomeningeal irritants in dogs.

Tonsils of 10 calves were inoculated with Pasteurella haemolytica (PH) and the degree of colonization was followed by collecting sequential tonsil wash specimens. Tonsils were colonized for at least 3 weeks after instillation of PH into the tonsillar sinus. Calves with colonized tonsils responded with serum and nasal secretion antibody responses to PH and to leukotoxin. Pasteurelia haemolytica was detected in nasal mucus specimens of 2 calves during the week after inoculation of the tonsils, but all other specimens were culture-negative. Infectious bovine rhinotracheitis virus-induced respiratory tract disease 25 days later did not elicit a population increase of PH in the tonsils, and did not elicit shedding of PH in nasal mucus.

The effects of 2 liquid formula diets differing in protein source were evaluated in orphan foals. The response of 7 foals fed a diet containing casein as the protein source, and 6 foals fed a diet containing a combination of whey and casein, was compared with the response in a reference group of 8 mare-raised foals. Orphaned foals were fed 150 kcal/kg of body weight/d, divided into 6 equal feedings of 25 kcal/kg. Formula intake was comparable among the experimental groups, and foals fed the liquid formula diet grew as well as mare-raised foals. There was no difference among groups in mean daily body weight gain, wither height, heart girth, body temperature, pulse, respiration rate, capillary refill time, or skin tenting. Insulin and blood glucose concentrations increased in both groups of foals fed formula diets, returning to prefeeding values within 4 hours. Differences among groups were found for serum alkaline phosphatase, alanine transaminase, cholesterol, creatinine, and glucose values; all other serum chemical values were comparable among groups. Plasma amino acid determinations revealed that arginine and ornithine were significantly lower in foals in both experimental groups than in reference foals, suggesting that arginine may have been the limiting amino acid in these diets. Diarrhea developed in foals in all treatment groups, but in most cases was self-limiting. These results suggest that the protein source of liquid formula diets may be less important in foals than in infants.

An electronic particle counter with attached particlesize analyzer was configured to directly determine concentration, mean cell volume, and volume distribution of erythrocytes in llama blood. Blood from 38 healthy llamas was used to characterize erythrocytic measurements and serum iron values for this species. Volume distribution curves for llama erythrocytes were similar in shape to those of other species. These curves had a unimodal, symmetric shape with a tail skewed to the right. Reference ranges for directly measured mean cell volume, erythrocyte concentration, hemoglobin concentration, and mean cell hemoglobin concentration were 21 to 28 fl, 11.3 X to 17.5 X 10(6) cells/microl, 12.8 to 17.6 g/dl, and 43.2 to 46.6 g/dl, respectively. Reference ranges for serum iron concentration, total iron-binding capacity, and transferrin saturation were determined to be 70 to 148 microg/dl, 230 to 370 micro g/dl, and 22 to 50%, respectively.

We evaluated the efficacy of 3 treatments for chronic obstructive pulmonary disease in horses: prednisone (400 mg/horse, PO, daily; n = 7), methyl sulfonmethane (10 g/horse, PO, q 12 h; n = 6), and clenbuterol hydrochloride (0.4 mg/horse, PO, q 12 h; n = 7). A fourth group acted as controls (n = 6) and was not treated. The treatment period lasted 10 days. Each horse was a member of 2 different groups for 10 days, separated by an 18-day interval of no treatment. All horses were housed together in an outdoor pen without bedding. Horses were fed alfalfa/grass hay mix ad libitum from a large feeder. The same batch of hay was fed throughout the study. Multiple physical and laboratory variables were monitored prior to, during, and at the end of each 10-day trial period. Changes in lung sounds, respiratory effort, degree of anal movement, nasal discharge, temperature, respiratory rate, or heart rate were not significant. Changes in arterial blood gas tensions, tracheal wash or bronchoalveolar lavage cytologic findings, or phagocyte function were not significant. All horses were tachypneic and most were tachycardic. The median value for Pao2 was below normal for all horses. All tracheal wash and most bronchoalveolar lavage cytologic findings represented a suppurative response. Negative linear correlation was observed between Pao2 and degree of respiratory effort in these horses (eg, as Pao2 decreased, the degree of respiratory effort increased).

We determined the position, dimensions, and structure of the kidneys, ureters, bladder, and urethra of 62 female sheep by use of ultrasonography. A 5.0-MHz convex transducer was placed over the right flank to examine the kidneys, and a 5.0 MHz-linear transducer was used to examine the bladder and urethra transrectally. All examinations were performed on sheep in standing position. The left kidney was 7.1 to 8.9 cm long, 3.4 to 5.5 cm wide, and 3.3 to 4.7 cm deep. Diameter of the parenchyma and renal sinus of the left kidney ranged between 1.1 and 1.9 cm and 1.1 and 2.0 cm, respectively. Circumference of the medullary pyramids varied between 2.1 and 3.3 cm. Similar ultrasonographic measurements were obtained for the right kidney. The diameter of the bladder varied between 0.3 and 6.9 cm in 96.8% of the sheep. The diameter of the bladder could not be determined in 32% of the sheep because it was > 10 cm, and, therefore, was beyond the penetration depth of the scanner. The only part of the urethra that could be ultrasonographically visualized was the internal urethral orifice. It had diameter between 0.1 and 0.2 cm. The ureters could not be ultrasonographically visualized in any of the sheep examined. The urinary tract of 8 sheep was examined 10 times within 2 weeks to examine whether measurements were reproducible. The interassay variation coefficient determined ranged from 3.1 to 31.8%, although for most variables, it ranged between 5 and 11%. Measurements for the length and width of the kidneys had the smallest interassay variation coefficient, whereas values obtained for diameter of the bladder and urethra, as well as thickness of the bladder, had the largest. It was concluded that the ultrasonographic findings described in this study can be used as references for diagnosis of morphologic changes in the kidneys, bladder, and urethra of sheep.

It has been established that L-gamma-glutamylated derivatives of alpha-amino acids are delivered more efficiently to the kidneys than are the parent alpha-amino acids. Therefore, we synthesized L-gamma-glutamyl-S-(1,2-dichlorovinyl)-L-cysteine (L-gamma-glutamyl-L-DCVC), the simplest L-gamma-glutamylated derivative of the nephrotoxic alpha-amino acid S-(1,2-dichlorovinyl)-L-cysteine (L-DCVC), and investigated its effects on renal function and ultrastructure in pentobarbital-anesthetized dogs. Intravenous doses of 23.15 and 92.60 micromoles of L-gamma-glutamyl-L-DCVC/kg of body weight induced significant increases in urinary protein output and significant decreases in the clearance of inulin during the 6-hour post-injection period. Changes were not observed in any of the other 13 renal function variables or in the 11 plasma and blood variables that were monitored throughout the same period. Both doses of L-gamma-glutamyl-L-DCVC induced renal ultrastructural lesions in the S1 and S2 cells of the canine proximal tubule; the remaining 8 cell types downstream and the glomeruli were not damaged. The onset and magnitude of renal function changes and the cell types affected by L-gamma-glutamyl-L-DCVC were virtually identical to those observed previously following IV administration of equivalent doses of L-DCVC to pentobarbital-anesthetized dogs. Rapid removal of the L-gamma-glutamyl group from L-gamma-glutamyl-L-DCVC (ie, deglutamylation) resulting in formation of the parent alpha-amino acid, L-DCVC, can best explain the extreme similarity in the nephrotoxic profiles of these 2 toxicants.

In this study, we tested the hypothesis that erythrocyte deformability is decreased in the development of cardiac failure induced by NaCl toxicosis. Deformability of erythrocytes and routine hematologic and biochemical variables were measured in 6 of 50 chickens that were given 5 g of NaCl/L in their drinking water from day 7 to day 42, and were compared with values in 6 of 50 healthy chickens given free access to tap water. Deformability was assessed by passing a 10% suspension of erythrocytes through a polycarbonate membrane with 5 micromoles pores. Chickens were euthanatized and heart and body weights were determined. Treatment with NaCl induced right-sided cardiac failure up to day 28. The ratios of heart weight to body weight were greater, for right ventricle by 20 to 64% and for left ventricle by 15 to 27%, attributable to NaCl treatment. Deformability of erythrocytes of NaCl-treated chickens was markedly decreased, in association with increased erythrocyte size and plasma Na+ concentration. However, only part of the decreased deformability could be explained by swelling of erythrocytes. Decreased deformability could not be explained by increased cell viscosity because mean corpuscular hemoglobin concentration, the primary determinant of erythrocyte viscosity, was decreased. Because decreased deformability of erythrocytes has been demonstrated previously to be associated with increased vascular resistance, decreased deformability may have contributed to the development of right-sided cardiac failure in these chickens.

Using a newly formulated selective medium containing cefoperazone, we isolated 72 Campylobacter strains in fecal samples from 397 diarrheic dogs and cats. Of these, 39 were thermophilic catalase-negative Campylobacter species. We identified these Campylobacter strains by DNA:DNA hybridization, using digoxigenin-labeled total genomic DNA of 4 Campylobacter reference strains (C jejuni, C coli, C lari, and C upsaliensis) as a probe. The labeling was done with a commercially available kit. We could identify 66 of the 72 Campylobacter isolates to the species level with this method; identification with probes always agreed with conventional test results. Of the 66 identified strains, 33 were C upsaliensis and 33 were C jejuni. Six isolates could not be assigned to a known species with probes or conventional tests. On the basis of our findings, C upsaliensis is more resistant to cefoperazone than to cephalothin, thereby explaining the unexpected recovery of these campylobacters on cephalosporin-containing media.