To differentiate the origin of high total lactate dehydrogenase (LD) activity in canine sera, a spectrophotometric method based on the preferential inhibition of cardiac LD isoenzymes by pyruvate was performed. Comparison with the electrophoretic separation of LD isoenzyme activities and determination of the hydroxybutyrate dehydrogenase-to-LD ratio indicated that the method proposed gave a better discrimination between cardiac and hepatic LD activities than did the other tests.

Ovariectomized, nonlactating cows were treated with IM injections of either physiologic saline solution or prostaglandin F2 alpha. Plasma concentrations of cortisol increased significantly by 30 to 60 minutes after injection of prostaglandin F2 alpha, but there were no significant increases in plasma concentrations of estradiol, progesterone, or testosterone. After saline solution treatment, there were no increases in any of the hormones measured.

A field study was performed to determine the effectiveness of benzathine cloxacillin for the treatment of infectious bovine keratoconjunctivits in cattle from 2 farms located in northern California. The study was performed between June and September of 1987. Affected calves ranging from 2 to 9 months of age were selected from the main herd when signs of corneal ulceration were observed. The study was conducted in 2 phases. For phase I, the affected calves of herd 1 (n = 21; Holsteins) and herd 2 (n = 43 Angus crossbred), were randomly assigned to 1 of 3 groups, and were either treated with 250 (n = 23) or 375 mg (n = 21) of benzathine cloxacillin, or mineral oil (n = 20) on days 1 and 4. For phase II, affected calves (n = 16; Angus crossbred, 3 to 9 months of age) from herd 2 were treated with benzathine cloxacillin (250 mg). Eight of these calves were retreated on day 4. After treatment, all calves were examined every 72 hours for 16 days. For examinations, a clinical score was assigned to each eye, and the surface areas of photographed corneal ulcers were measured. The ocular secretions were collected and examined culturally for Moraxella bovis. On days 7, 10, and 13, the calves treated with benzathine cloxacillin had significantly (P less than 0.05) lower lesion scores, compared with the controls. The percentage of day-1 area measurements on posttreatment days 4, 7, and 10 were significantly larger in the controls than in the treated calves. The mean healing times of corneal lesions in the 2 antibiotic treatment groups were significantly (P less than 0.05) shorter than in the controls. In the treated calves, the healing times of corneal ulcers less than or equal to 0.05 cm in diameter on day 1 were significantly (P less than 0.05) shorter than the healing times of larger lesions. The healing times of the corneal ulcers in the Angus crossbred calves were significantly (P less than 0.05) longer than the healing times of the Holsteins. The controls had the greatest number of nonhealed corneal ulcers on day 16. The number of calves that remained infected with M bovis on days 4, 7, 10, and 13 was significantly less in both groups of treated calves than in the controls. The scores, surface area measurements, healing times, and the M bovis isolation frequency in the calves of the 250-mg and 375-mg and 1- and 2-dose treatment groups were not significantly different. The minimal inhibitory concentrations (MIC) of penicillin, cloxacillin, and ampicillin in the day-16 isolates from benzathine cloxacillin-treated herd-2 calves were greater than in isolates from corresponding calves on observation day 1; however, twofold increases of the respective MIC of pretreatment and day-16 specimens were not observed. The highest MIC of ampicillin, cloxacillin, gentamicin, oxytetracycline, and penicillin were 0.5, 8.0, 0.5, 2, and 1 migrogram/ml, respectively, for isolates collected during the final study week.

Thirty mares with normal estrous cycles were allotted equally to 5 groups and infused with 250 ml of saline (NaCl) solution in utero on the seventh day after ovulation to test the effects of temperature, osmolarity, or pH of the saline solution on prostaglandin F2 alpha (PGF2 alpha) release and luteolysis. Intrauterine infusion of phosphate-buffered saline solution failed to alter the duration of the luteal phase, compared with the control group. Similarly, increasing the temperature of phosphate-buffered saline solution to 42 C or increasing (600 mosm) or decreasing osmolarity (less than 10 mosm) did not change the duration of the luteal phase. Decreasing the pH of saline solution to 3 caused significant (P less than 0.0001) re leases of PGF2 alpha from the uterus within the first hour after infusion, and the luteal phase was shortened to 8.8 +/- 1.0 days (mean +/- SEM; control, 15 +/- 1.2 days). The results of this study showed that pH is main factor in eliciting PGF2 alpha release by intrauterine infusion of a saline solution, whereas increased temperature and osmolarity have no effect on the release of PGF2 alpha. The intrauterine infusion of sterile water or physiologic saline (NaCl) solution has been used to induce estrus in mares for the past 50 years. Many investigators 1-10 have reported that intrauterine infusion of physiologic saline solution or water at body temperature (37 C or warmer up to 45 C) causes most "anestrous" mares to return to estrus in 1 to 8 days. The mare's ability to respond to intrauterine infusion was further defined when Arthur 11,12 demonstrated that estrus could be initiated only in mares in middiestrus or in pseudopregnancy, and Ginther and Meckley 13 reported intrauterine infusion was effective only during days 5 to 9 of diestrus. We subsequently demonstrated that the effect of intrauterine infusion of saline solution involved shortening the luteal phase.

Colostrum-deprived lambs (10 to 20 days old) were inoculated with either ovine adenovirus type 6 (OAV-6; n = 6), Pasteurella haemolytica type A1 (n = 6), or OAV-6 followed by P haemolytica 5 days later (n = 10). Another group (n = 3) served as sham-inoculated controls. Lambs inoculated with OAV-6 or P haemolytica developed mild and moderate respiratory tract disease of 6 and 3 days' duration, respectively. Lambs inoculated with virus and bacteria developed clinical signs of respiratory tract disease of greater intensity and duration (9 days) than with either agent alone. Within 3 hours of bacterial inoculation, all lambs that received P haemolytica were anorectic, listless, and febrile, and had hyperpnea and dyspnea. Ovine adenovirus type 6 was isolated from all virus-inoculated lambs. Although P haemolytica was not recovered from all bacteria-inoculated lambs, it was recovered for a longer period in the group that received both agents. Antibody to OAV-6 was detected in virus-inoculated lambs as early as day 6 after inoculation. The control lambs remained clinically normal and neither virus nor bacteria were recovered at necropsy.

Genomic DNA polymorphisms obtained by restriction fragment-length polymorphism from healthy horses and horses with hereditary multiple exostoses were analyzed. These DNA were digested by 12 restriction enzymes and were hybridized against 6 isotopically labeled oncogene probes. Hybridization was not detected with the viral oncogene, v-ras, which indicated this oncogene was absent in the equine genome. Oncogenes (c-raf-1, c-fes, c-myb, c-myc, and c-sis) were present and had similar hybridization patterns and signal intensities in DNA from healthy horses and horses with hereditary multiple exostoses. Unique and distinct restriction fragment-length polymorphisms were detected with the c-raf-1 probe only in BamHI- and PstI-digested equine DNA.

Male Holstein calves were each inoculated with 350,000 sporulated oocysts of Eimeria bovis. Two calves were given decoquinate (0.5 mg/kg of body weight) continuously in dry feed for 29 days, and 2 calves each were given 0.5, 1, or 1.5 mg of decoquinate/kg on an every 2nd-or 3rd-day schedule for 29 days. Calves given decoquinate continuously did not discharge oocysts but had slightly loose feces. In general, the number of oocysts discharged increased and fecal consistency decreased as the time between feeding of medicated feed increased. Calves given 0.5 or 1.5 mg of decoquinate/kg every 3rd day discharged more oocysts and had more diarrhea than did calves given 1 mg of decoquinate/kg every 3rd day. At postinoculation day 29, calves were euthanatized. At necropsy, intestinal tissues of calves given decoquinate were mostly normal. Apparently, reduced infections along with the elapsed time were sufficient to resolve most intestinal lesions caused by the coccidia. Decoquinate was most effective when fed continuously at 0.5 mg/kg. However, when fed at 1 or 1.5 mg of decoquinate/kg every 2nd day or 1.5 mg of decoquinate/kg every 3rd day, oocyst production was reduced and clinical coccidiosis was prevented.

The Langendorff isolated heart preparation was adapted to determine the effect of furazolidone (0.5 and 2 migrogram/ml of perfusate) on hearts of 3-week-old broiler chickens. Following 115 minutes of perfusion, both concentrations of furazolidone caused approximately a two-fold increase in myocardial vascular resistance and a six-fold increase in myocardial vascular resistance and a six-fold increase in lactate dehydrogenase release into the effluent fluid, compared with a control perfused group of isolated hearts (P less than 0.01). Ultrastructural alteration differences were not found between the drug-treated and control groups. It was concluded that: (i) furazolidone, at concentrations only moderately above therapeutic plasma concentrations, caused detrimental changes in myocardial vascular resistance and lactate dehydrogenase release and (ii) the isolated chicken heart preparation is an example of a cost-effective, reliable laboratory tool for screening potential cardiotoxins.

Oxidative respiratory burst activity was examined in lavage-procured bovine pulmonary alveolar macrophages. Nonstimulated alveolar macrophages released a minimal quantity of superoxide anion and had small amounts of glucose flux through the pathways of energy metabolism. Nonstimulated cells metabolized substantial amounts of glucose through the hexose monophosphate shunt. Stimulation with opsonized zymosan particles induced a tonfold increase in the release of superoxide anion and a twofold increase in the flux of glucose through the hexose monophosphate shunt and the pathways of energy metabolism. Preliminary observations also indicated that the magnitude of the burst varied between sets of bronchoalveolar cells obtained from the same calf over time.

Terminal renal dysfunction (TRD) was induced in 2 groups of dogs by partial surgical ablation of the kidney. Dogs of a control group and of 1 of the TRD groups were maintained on a diet containing normal phosphorus concentration, whereas dogs of the other TRD group were maintained on a low-phosphorus diet. Mild anemia developed in dogs of both TRD groups and could not be attributed to iron deficiency, increased erthrocyte concentration of 2,3-diphosphoglycerate, or absolute deficiency of erythropoietin (EP). Subsequently, all dogs were acutely depleted of approximately 25% of their blood volume. Erythropoietin concentration in dogs of the TRD groups was lower than that of controls, however, erythroid regenerative capacity was comparable with that of control dogs when plasma parathyroid hormone (PTH) concentration was lowered by reduced dietary intake of phosphorus. The PCV in dogs of the chronic TRD goups had a slight positive correlation with serum EP concentration, and a significant (P lesss than 0.05) negative correlation with plasma PTH and serum phosphorus and creatinine concentrations, using a correlation matrix. There was no longer a significant correlation between plasma PTH concentration and PCV after controlling for serum creatinine concentration by use of a multiple linear regression analysis. A significant (P less than 0.05) negative correlation also was observed between plasma PTH and serum EP concentrations, but not between serum EP and phosphorus or or creatinine concentrations. Significance of the EP and PTH association was reduced when analyzed, using a multiple linear regression analysis that included serum creatinine values. According to these data, PTH does have an independent effect on EP concentration, but the relationship between PTH and EP is not sufficiently strong to account for the genesis of the anemia of chronic TRD.