Phenylbutazone toxicity in ponies

The oral administration of phenylbutazone at a dose rate of approximately 10 mg per kg per day for seven to 14 days resulted in the development of signs of toxicity in seven of eight ponies treated. Clinical signs included anorexia, depression and abdominal oedema. Blood biochemical determinations showed a decrease in total plasma protein and calcium concentrations with an increase in urea concentration. These changes were considered indicative of water retention. Three of the ponies died during treatment following the development of shock. Shock was considered to arise from the submucosal oedema of the large intestine observed on necropsy. Oral ulceration was also found in these animals. In two ponies intravenous administration of phenylbutazone (4.0 mg per kg) for seven days was studied. In one of these ponies a marked decrease in total plasma protein concentration occurred.     

Studies of parvovirus vaccination in the dog: the performance of live attenuated feline parvovirus vaccines

The performance of three live attenuated feline parvovirus vaccines licensed for use in the dog was studied. At the end of the primary vaccination course 67 per cent of dogs had inadequate antibody levels (less than or equal to 32) as measured by a haemagglutination inhibition test. Interference by maternal antibody accounted for some of the failures but the fact that there was no significant difference in performance between dogs vaccinated at 12 weeks or 16 weeks of age indicated that maternal antibody was not the only factor.     

RELATIONSHIP BETWEEN PELVIC DIMENSIONS, OTHER BODY MEASUREMENTS AND DYSTOCIA IN DORSET HORN EWES

Fifteen live and 16 post slaughter measurements were recorded from each of 29 mature Dorset Horn ewes in an investigation of pelvic dimensions and their association with past history of dystocia or difficult birth amongst the ewes. For comparison with a breed having a low incidence of dystocia, similar measurements were recorded from 6 mature Border Leicester ewes with no previous history of dystocia.
The range in size of the Dorset Horn pelves was considerable, with conjugate diameter being more variable than transverse diameter (P < 0.05) and a more important cause of variation in pelvic area. A higher incidence of dystocia amongst the Dorset Horn ewes tended to be associated with smaller pelvic areas (r =—0.34; P = 0.08). Pelvic area and conjugate diameter were significantly less (73.4 v 82.8 cm², P < 0.01; and 9.9 v 10.9 cm, P < 0.05, respectively) for those ewes which had dystocia at more than 65% of their lambings, suggesting that pelvic area and conjugate diameter may be factors with critcial levels in predisposition to dystocia. The Border Leicester pelves were 21 % greater in area (P < 0.01) and 17% greater in conjugate diameter (P < 0.01) than the Dorset Horn pelves, although there was no difference in their transverse diameters.
In general, measurements in the region of the pelvis were closely correlated with transverse diameter of the pelvis but not with pelvic area or conjugate diameter. Forelimb length and bodylength were the only measurements recorded in the live Dorset Horn ewes that were significantly correlated (P < 0.01) with both pelvic area (r = 0.53 and r = 0.47 respectively) and conjugate diameter (r = 0.48 and r = 0.49 respectively). However, these live measurements accounted for less than 35% of the variation in conjugate diameter and pelvic area when included in a multiple regression equation.     

Inhibition of DNA synthesis by diflubenzuron in pupae of the stable fly Stomoxys calcitrans (L.)

Biochemical assays of stable fly pupae treated with diflubenzuron at the white prepupal stage and then injected with either [³H]thymidine or [¹⁴C]thymidine showed no differences in uptake of the thymidine at 0–4, 0–24, 20–21, or 22–24 hr after injection of the radiolabeled thymidine. However, at 32–36 hr the diflubenzuron pupae incorporated only 10–11% of the amount of labeled thymidine incorporated by the untreated pupae. Autoradiographs taken from diflubenzuron-treated pupae at 22–24 and 32–36 hr after injection of the labeled thymidine showed that a reduction in DNA synthesis had occurred in cells originating from the imaginal epidermal histoblasts. The reduction in DNA synthesis at 22–24 hr was not detectable by the biochemical assay since the number of proliferating epidermal cells was too small a proportion of the total number of cells undergoing histogenesis at this time period. Thus, the insect growth regulator, diflubenzuron, appears to be cell specific in this species of fly in that the reduction in DNA synthesis is observed only in cells originating from the imaginal epidermal histoblasts. However, it is not known at this time whether this effect is primary or secondary.     

Influence of calf removal on the serum luteinizing hormone response to naloxone in the postpartum beef cow

Twelve anestrous, postpartum beef cows were used to determine the effect of calf removal on the effect of naloxone on serum luteinizing hormone (LH) concentrations. On d 1, six cows were injected iv with saline and six with 200 mg naloxone dissolved in saline. Blood samples were taken at 15-min intervals for 2 h before and 2 h after naloxone or saline administration. At the beginning of blood sampling, calves were removed from three cows in each treatment. At 48 h after calf removal (d 3), all cows were injected iv with 200 mg naloxone and blood samples were collected as on d 1. On d 1, naloxone treatment increased (P less than .01) serum LH concentrations from 1.2 +/- .3 ng/ml at time 0 to 4.3 +/- .6 ng/ml and 4.7 +/- .8 ng/ml at 15 and 30 min, respectively. Injection of saline had no effect on serum LH concentrations. Forty-eight-hour calf removal increased (P less than .01) serum LH concentrations in five of six cows (1.7 +/- .8 vs 4.4 +/- 1.2 ng/ml). Naloxone treatment failed to increase serum LH concentrations in these cows. Injection of naloxone increased (P less than .01) serum LH concentrations in the one cow that did not exhibit an LH increase after calf removal and in six cows whose calves were not removed (1.4 +/- .2 vs 4.4 +/- .5 ng/ml). The present study provides additional evidence that endogenous opioids regulate LH in the postpartum beef cow. We hypothesize that suckling stimulates an opioid inhibition of LH secretion and removal of the suckling stimulus removes the opioid inhibitory tone.     

Use of a low dose synthetic ACTH challenge test in normal and prednisone-treated dogs

The utility of a low dose (1 microgram/kg) synthetic ACTH challenge test in detecting moderate reductions in adrenocortical sensitivity in dogs was examined. First, the adrenocortical responses to an intravenous bolus of either 1 microgram/kg or 0.25 mg per dog of synthetic ACTH were compared in two groups of normal dogs. While plasma cortisol concentrations were similar in both groups 60 minutes after ACTH injection, dogs given 0.25 mg ACTH showed continued elevations in plasma cortisol concentrations at 90 and 120 minutes after ACTH injection. Later, the dogs previously tested with the 1 microgram/kg ACTH challenge were given a single intramuscular dose of prednisone (2.2 mg/kg) and retested with 1 microgram/kg of ACTH one week later. Plasma cortisol levels were significantly reduced after ACTH injection in dogs previously given prednisone demonstrating that a single intramuscular prednisone dose causes detectable adrenocortical suppression one week after administration. The 1 microgram/kg synthetic ACTH challenge test provides a sensitive means for evaluating adrenocortical suppression in dogs.     

Chronic nephritis in a pony

The clinical and pathological features of a case of chronic nephritis in a 17-year-old pony was described. Measurement of fluid intake and laboratory analysis of sequential blood and urine samples helped in establishing an accurate diagnosis. The case demonstrates that although chronic renal disease is not well documented in the horse it should nevertheless be considered in the differential diagnosis of conditions characterised by progressive loss of weight.