Estradiol was administered to 3 steers (0.12 mg/kg of body weight/d for 14 consecutive days), followed by 2 days of nonfeeding (starvation). During estradiol administration, liver nuclear estrogen receptor and serum apolipoprotein B-100 (apoB-100), as well as serum triglycerides concentrations were increased, compared with values before administration. Starvation, together with interruption of estradiol administration, resulted in rapid decreases of the receptor, serum apoB-100, and serum triglycerides concentrations, and increase of nonesterified fatty acids concentration. Of the 3 steers, 2 had higher liver triglyceride content, compared with values before treatment. In the control group (3 steers that received vehicle alone, then starved similarly), these concentrations, except for serum nonesterified fatty acids and triglycerides concentrations after starvation, were not changed. In another experiment, serum apoB-100 concentration in dairy cows was significantly (P < 0.05) lower at parturition than values before and after parturition. These results indicate that estradiol may be involved in development of fatty liver in cattle.

Immunocytochemical analysis of equine synovial membranes revealed presence of several neuropeptides, including substance P (SP), neurokinin A, and neuropeptide Y, in nerves of the radiocarpal, middle carpal, and metacarpophalangeal (fetlock) joints. Within the subsynovium, these neuropeptides were located perivascularly, whereas in the fronds, only neuropeptide Y was restricted to the vessels of the synovial membrane. Only SP and neurokinin A were found in the intimal layer. The intimal layer of the metacarpophalangeal joint contained more SP-immunoreactive fibers than were observed in the intimal layer of the radiocarpal joint. Substance P also was detected in the synovial fluid from all 3 joints, but mean +/- SD concentrations were significantly different only between the middle carpal joint (37.56 +/- 5.48 fmol/ml; n = 6) and the metacarpophalangeal joint (55.80 +/- 8.33 fmol/ml; n = 5) and between the middle carpal joint and the radiocarpal joint (52.43 +/- 14.60 fmol/ml; n = 7).

Brain capillary function was assessed in 4- to 6-week-old calves given lead acetate (15 mg/kg of body weight) orally for 7 to 8 days. Neurologic signs of lead poisoning included CNS depression, blindness, and hyperesthesia. Brain capillaries were isolated from cerebral cortex of control and lead-treated calves and evaluated for metabolic indicators, ion transport, and prolyl hydroxylase activity. In lead-treated calves, the rate of glucose metabolism was less than half that in controls. Ion efflux of 45Ca or 36Cl from endothelial cell suspensions was not affected by lead treatment. Prolyl hydroxylase activity in endothelium and proline-to-hydroxyproline ratio in endothelial basement membranes were similar in control and lead-poisoned calves. Results indicate that lead may inhibit energy metabolism, but not ion transport or collagen biosynthesis in brain capillaries of calves and, compared with suckling rats, damage to the blood-brain barrier is less important. In calves, neuronal tissue may be the primary target for the CNS effects of lead.

We investigated the effects of a range of IV administered doses of omeprazole (0.125 to 2.0 mg/kg of body weight) on gastric pH (monitored by indwelling electrode) and plasma gastrin concentration, compared with those of IV administered ranitidine (1.0 mg/kg) in 4 Welsh mountain-type ponies. Pharmacokinetic variables of IV administered omeprazole also were examined. Episodes of high gastric pH in the basal state obscured the effect of acid suppression on intragastric pH; however, omeprazole induced dose-dependent increase in mean gastric pH (P < 0.01) during the 11 hours after its administration. In the presence of acid-suppressant treatment, plasma gastrin concentration correlated significantly with gastric pH (Spearman's rank correlation coefficient, p = 0.445, P < 0.01), whereas basal pH and plasma gastrin concentration were not correlated. The effect was not great, and a dose-dependency was not found. Intravenously administered omeprazole was subject to two-compartment pharmacokinetics, and there was evidence for saturable steps in the redistribution and elimination phases. Dosage of 0.25 mg/kg induced approximately half-maximal inhibition of basal gastric pH in these ponies and was associated with area under the concentration vs time curve of 0.7 micromoles.h/L, which corresponds reasonably with results of other species. Omeprazole may represent a useful alternative acid-suppressant agent in horses, but further work is required to relate the dose-dependent effects found in this study to well-defined targets of acid suppression in clinical cases.

Intramural vascular patterns of the jejunum and colon were evaluated during ischemic strangulation obstruction (ISO, 70 minutes) and subsequent reperfusion (60 minutes) in 7 adult anesthetized horses. Microvasculature of experimental and control segments was described by comparison of results from microangiography, light microscopy, and scanning electron microscopy of vascular replicas. Experimental and control segments with isolated vascular arcades were removed either immediately after the experimental period or after 60 minutes of reperfusion. Blood was flushed from the vascular system by use of isotonic NaCl, and the segments were divided. Half of each segment was perfused with a modified radiopaque medium for microangiographic evaluation, and half was perfused with dilute methylmethacrylate to create a vascular replica to be studied by scanning electron microscopy. Microangiographic section also were evaluated for histologic changes. Microvasculature of jejunal control segments and all colon segments was similar to described normal microvasculature of the equine jejunum and ascending colon. In jejunal ISO segments, intramural perfusion was redistributed away from the mucosa. In the villi, the central arteriole was short and convoluted and the subepithelial capillaries were not filled. The submucosal vessels and crypt capillaries were congested, compared with those of controls, and the serosal vessels were not filled in the ischemic segments. Histologic grade II-III mucosal lesion was seen in jejunal ISO segments. Reperfused jejunal segments had a transmural hyperemic response, and previously unfilled capillaries were observed in all intestinal layers. After reperfusion, the mucosal lesion progressed to grade III-IV and a cellular infiltrate and edema formation were observed in the serosa. The intramural vasculature of the ischemic and reperfused colon remain unchanged. Minimal histologic damage was observed in the colon after 70 minutes of ISO or after 60 minutes of reperfusion.

Twelve healthy dogs were used to determine the cardiorespiratory effects of IV administered ketamine (10 mg/kg of body weight) and midazolam (0.5 mg/ kg). Half the dogs received a ketamine-midazolam combination (K-M) as a bolus over 30 seconds and the other half received the K-M as an infusion over 15 minutes. Induction of anesthesia by use of K-M was good in all dogs. Ketamine-midazolam combination as a bolus or infusion induced minimal cardiorespiratory effects, except for significant (p < 0.05) increases in mean heart rate and rate-pressure product. The increase in heart rate was greater in dogs of the infusion group. Mild and transient respiratory depression was observed in dogs of both groups immediately after administration of K-M, but was greater in dogs of the bolus group than in dogs of the infusion group. Duration of action of K-M for chemical restraint was short. Salivation and defecation were observed in a few dogs. Extreme muscular tone developed in 1 dog after K-M bolus administration.

Effects of strategic anthelmintic treatment on pathophysiologic and immunologic changes induced by infection with Ostertagia ostertagi and Cooperia oncophora were studied in 2 groups, of 12 calves each: an infected group, inoculated with 200,000 mixed O ostertagi and C oncophora third-stage larvae (L3) on day 1; and an infected-treated group, similarly inoculated, but treated with ivermectin at 9 and 33 days. All calves were also inoculated at 12 weeks with Brucella abortus vaccine, at 13 weeks with bovine rhinotracheitis vaccine (bovine herpesvirus 1), and at 14 weeks with a soluble O ostertagi L3 extract, then were allowed to graze on a contaminated pasture. Four calves from each group were slaughtered at 7, 11, and 19 weeks of the study. Calves of the infected group had significantly (P < 0.05) lower weight gain than did those in the infected-treated group (60.90 kg vs 75.86 kg). They also had high plasma pepsinogen and serum gastrin values, and low serum albumin concentration from 2 or 4 weeks. Calves in the infected-treated group had steady weight gain and no significant changes in albumin and gastrin values. They also had less severe abomasal lesions and higher carcass yield. Compared with calves of the infected-treated group, those of the infected group had significantly (P < 0.05) lower blood lymphocyte reactivity to phytohemagglutinin at 14 and 16 weeks, to concanavalin A at 10 weeks, to pokeweed mitogen at 14 weeks, and to soluble O ostertagi L3 extract at 2, 4, and 14 weeks. They also had significantly (P < 0.05) lower IgG1 concentration to excretory-secretory antigens of the fourth-stage larvae of O ostertagi at 13, 18, and 19 weeks. In addition, they had significantly (P < 0.05) higher total mean eosinophil count. Antibody responses to B abortus and bovine herpesvirus 1, however, were not different between the 2 groups.

Changes in platelet indices (platelet count and platelet size) and PCV associated with thyroid disease were studied in 7 dogs with hypothyroidism and 21 cats with hyperthyroidism that were admitted to the veterinary teaching hospital. Compared with control (euthyroid) dogs, dogs with hypothyroidism had higher platelet count (P = 0.003), smaller platelet size (P = 0.01), and lower PCV (P = 0.02). Comparison of the group of hyperthyroid cats with a group of similarly aged, clinically normal cats with normal thyroxine values indicated that the group of hyperthyroid cats had significantly (P = 0.03) higher mean platelet size than did control cats, but differences were not found in mean platelet count or PCV. Results of this investigation indicate that the changes in platelet size reported in human beings with thyroid endocrinopathies also are found in animals so-affected. Although the pathogenesis of platelet abnormalities in animals with thyroid derangement is unclear and likely is multifactorial, the observed relation between platelet and erythrocyte production in this group of dogs is consistent with reports of an inverse relation between thrombocytopoiesis and erythropoiesis in iatrogenically hyperthyroid mice and in mice exposed to hypoxia.

Using a force plate, ground reaction force (GRF) patterns at take-off and landing between the hooves and the ground were recorded for all limbs of 5 Dutch Warmbloods jumping a 0.8-m vertical fence from the right-leading canter. Distribution of the GRF and force impulses over the 4 limbs at take-off and landing were considerably different from those recorded at the normal canter. At take-off, the propulsory GRF of the hind limbs were 3 to 5 times higher than at the normal canter, depending on the jumping technique of the horse. At landing, the propulsory GRF were mainly increased in the trailing forelimb and in both hind limbs. The vertical GRF amplitudes and force impulses were of similar magnitude to those at the canter, although increases up to 160% were found in the hind limbs of the horse with the worst jumping technique. The trailing forelimb carried the highest loads, up to twice the animal's body weight; GRF amplitudes tended to increase when higher fences were used. However, the jumping technique of the horse may have more influence, because an easily jumping horse could clear a 1.3-m-high fence with similar loads on the limbs.

The IgG and IgM classes of antibodies to a water-soluble antigen preparation derived from microsporum canis were determined by ELISA in the sera of 79 cats with dermatophytosis confirmed by results of fungal culture, and of 46 specific-pathogen-free-derived, barrier-maintained cats with no previous exposure to dermatophytes. Of the 79 cats with dermatophytosis, the species isolated were: M canis from 72, M gypseum from 6, and Trichophyton mentagrophytes from 1. Concentrations of soluble M canis antigen-specific IgG and IgM were significantly (P < 0.05) higher in the cats with dermatophytosis than in the control cats. The IgG concentration was larger than or equal to 2.0 ELISA units/ ml in 71% of the cats with dermatophytosis and in 9% of the control cats, whereas IgM concentration was greater than or equal to 4.0 ELISA units/ml in 38% of the cats with dermatophytosis and in 11% of control cats. There was no significant difference in either IgG or IgM values between the cats with M canis infection and those with other non-M canis dermatophyte infections.