The effects of dexamethasone (0.2 mg/kg of body weight; IV, IM, and PO) and methylprednisolone acetate (120 mg, given intra-articularly) on serum osteocalcin and cortisol concentrations were studied in 6 horses. Serum osteocalcin and cortisol concentrations were serially monitored after each treatment. A significant (P < 0.05) decrease in serum osteocalcin and cortisol concentrations was observed from 12 to 24 and 2 to 48 hours, respectively, after IV and IM administrations of dexamethasone. Serum osteocalcin and cortisol concentrations were significantly decreased from 6 to 48 and 3 to 72 hours, respectively, after oral administration. In contrast, a change in serum osteocalcin concentration was not detected after intra-articular administration of methylprednisolone. Oral, IV, or IM treatment with 0.2 mg of dexamethasone/kg caused a decrease in serum osteocalcin concentration in horses.

Objective--To determine the relative role of endogenous prostaglandin F2 alpha (PGF2 alpha) secretion in cloprostenol-induced abortion in mares that no longer require luteal progesterone secretion for maintenance of pregnancy, and to evaluate the ability of a prostaglandin cyclooxygenase inhibitor (flunixin meglumine) to prevent cloprostenol-induced abortion. Design--The effect of flunixin meglumine on PGF2 alpha secretion and outcome of pregnancy was compared between mares treated with cloprostenol only and mares treated with cloprostenol plus flunixin meglumine. Animals--Five pregnant mares, aged 4 to 15 years, of light-horse type. Procedure--Cloprostenol (250 micrograms) was administered at 24-hour intervals to 5 pregnant mares. Flunixin meglumine (500 mg, IV) was administered at 8-hour intervals starting 15 minutes before the first cloprostenol administration. Hourly blood samples were analyzed for 15-ketodihydro-PGF2 alpha, progesterone, and estrogen concentrations. Previously reported data on cloprostenol-induced abortion in 6 pregnant mares treated daily with cloprostenol only were used as historic controls. Results--The mean (+/- SEM) interval from first cloprostenol administration to fetal expulsion 56.4 (+/- 13.7) hours and number of cloprostenol administrations 3.2 (+/- 0.6) in the 5 flunixin meglumine-treated mares were not significantly different, compared with values for 6 pregnant mares treated daily with cloprostenol only, 48.6 (+/- 5.6) hours and 2.8 (+/- 0.2) cloprostenol administrations. Flunixin meglumine did not inhibit endogenous PGF2 alpha secretion. Prostaglandin F2 alpha secretion rates on the day before and day of fetal expulsion were similar in both groups. Conclusion--Flunixin meglumine at a dosage of 500 mg/animal, administered IV every 8 hours, is ineffective in modulating uterine PGF2 alpha secretion during cloprostenol-induced abortion. Clinical Relevance--Flunixin meglumine is ineffective in the modulation of prostaglandin-induced uterine PGF2 alpha secretion and, therefore, does not offer a viable alternative for the prevention of abortion in mares at risk of abortion because of systemic illness.

Uptake of ferritin by M cells in follicle-associated epithelium at various sites in the small and large intestines was examined in 4 healthy 5-week-old pigs by use of electron microscopy. A 2.5% solution of ferritin in saline was injected into ligated loops of the jejunum and ileum containing aggregations of lymphoid follicles (Peyer's patches), as well as into intestinal loops containing lymphoglandular complexes at the ileocecal junction, in the central colonic flexure, and in the rectum. As negative control, saline solution was injected into loops at identical localizations. After an exposure period of 2 hours, uptake of ferritin by M cells, but not by enteroabsorptive cells of the small and large intestines, was observed. Numbers of M cells with ferritin and total M cells were counted and the percentage was calculated. Total number of M cells was highest in lymphoglandular complexes in the rectum and lowest on domes of the ileal Peyer's patch. High numbers of M cells with ferritin were found on domes of the jejunal Peyer's patch, and in lymphoglandular complexes at the ileoceral entrance and in the rectum. Only a few M cells on domes of the ileal Peyer's patch and in lymphoglandular complexes in the central colonic flexure contained ferritin. The percentage of M cells with internalized ferritin was similar on domes of the ileal Peyer's patch, and in lymphoglandular complexes at the ileocecal junction and in the rectum. It was higher on domes of the jejunal Peyer's patches and lower in lymphoglandular complexes of the central colonic flexure. Ferritin was found in the apical tubulovesicular system, multivesicular bodies, and a few vacuoles in the central area of M cells. Ferritin was exocytosed into the lateral intercellular spaces next to M cells. Uptake of ferritin by intraepithelial cells in the follicle-associated epithelium could not be documented, but ferritin was present in vesicles of subepithelial macrophages.

A series of studies was conducted to identify a practical measure for preventing dental calculus formation in dogs. The studies involved a colony of 27 Beagles that received an initial dental prophylaxis. The dogs were then stratified on the basis of their normal rate of calculus formation and randomly assigned to parallel groups within each strata. During 4-week test periods, a variety of experimental regimens were instituted, followed by clinical assessments of calculus. Major observations were that a crystal growth inhibitor, soluble pyrophosphate, incorporated into a dry dog food modestly reduced calculus formation when used at high concentrations; anticalculus effects attributable to this agent were significant (P < 0.05) only when it was used as a surface coating the coating of dry dog chow or plain biscuits with a calcium sequestrant, sodium hexametaphosphate (HMP), provided the greatest benefit and resulted in significant (P < 0.05) reductions in calculus formation of about 60 to 80%, depending on the dosage regimen; and the feeding of a single daily snack of 2 HMP-coated plain biscuits (0.6% HMP) decreased calculus formation by nearly 80%. We concluded that the coating of dry dog chow or plain dog biscuits with HMP is an effective means of reducing calculus formation in dogs.

Dogs are particularly susceptible to development of glucocorticoid-induced hepatopathy, but the mechanisms are not well understood. We investigated the pathogenesis of glucocorticoid hepatopathy by examining sequential morphologic and biochemical changes in the liver of dogs during steroid administration. Six adult Beagles were given prednisolone acetate (4 mg/kg of body weight, once daily for 24 days, IM). Serum samples and percutaneous liver biopsy specimens were obtained before the start of the study (treatment day [TD] 0) and at TD 5, 10, 15, and 25. There were significant (P < 0.05) and progressive increases in serum activities of alkaline phosphatase, gamma-glutamyltransferase, and alanine transaminase. Light microscopic changes in liver biopsy specimens included progressive hepatocellular swelling and vacuolation. Electron microscopy revealed glycogen accumulation, peripheral displacement of organelles, and prominent dilatation of bile canaliculi, compared with findings at TD 0. Liver biopsy specimens taken at TD 25 had significantly (P < 0.05) increased activities of the plasma membrane enzymes, alkaline phosphatase and y-glutamyltransferase, and 5'-nucleotidase was significantly (P < 0.01) decreased. Subcellular fractionation on reorientating sucrose density gradients revealed high-density peaks of alkaline phosphatase and gamma-glutamyltransferase, compatible with a specific increase in the biliary canalicular component of the enzyme activities. Neutral gamma-glucosidase activity was shifted to the denser fractions, indicative of an increase in the proportion of rough to smooth endoplasmic reticulum and consistent with enhanced synthesis of plasma membrane proteins. There also was evidence for progressive increase in fragility of intracellular organelles, particularly lysosomes. These findings indicate that glucocorticoid he particularly in dogs is associated with progressive alterations not only to the plasma membrane, but also to other subcellular organelles.

Loline and ergot alkaloids found in endophyte-infected (Acremonium coenophialum) tall fescue (EITF) cause vasoconstriction of equine vessels in vitro. An aggregate risk study was used to evaluate the association between horses exposed to EITF and development of laminitis. Veterinary teaching hospitals participating in the Veterinary Medical Data Base were grouped by whether equine accessions were likely to have been at high, moderate, or low risk for exposure to EITF. From 1980-1990, there were 185,781 accessions, of which 5,536 had diagnosis of laminitis. Proportion of equine accessions with laminitis reported by veterinary teaching hospitals for high, moderate, and low risks, were 3.41, 3.04, and 2.00 cases/100 accessions, respectively (P < 0.0001). Comparison of the proportion of accessions with laminitis in the high- and moderate-risk groups with that in the low-risk group revealed significant differences between risk groups over all months (P = 0.063) and differences from month to month within risk groups (P = 0.0001). If the difference among risk groups is attributed entirely to exposure to EITF, the population-attributable risk is 7 cases/1,000 admissions, or 15% of all admissions for laminitis at veterinary teaching hospitals in our data base. Preliminary data support an association between hoses exposed to EITF and increased risk of laminitis; however, studies at the individual animal level are indicated to confirm this hypothesis.

A longitudinal survey of 820 cats in 73 households was conducted over a period of 6 years to establish the fate of pet cats that were seropositive after natural exposure to feline coronavirus (FCoV). In particular, their risk of developing feline infectious peritonitis (FIP) was determined. The seropositive cats were assigned to 1 of 3 groups: cats from households in which FIP had recently been diagnosed; cats from households in which FIP had not been diagnosed, but from which kittens had been relocated and subsequently died of FIP; and cats from households in which FIP had not been diagnosed. Cats in the first group were not at greater risk of developing FIP than were cats in the other 2 groups. Consequently, any household in which seropositive cats live must be considered a potential source of FCoV that can cause FIP. There was no evidence that the enhanced disease, which has been described after experimentally induced infection of seropositive cats, exists in nature. Thus, analysis of the survival of the seropositive cats over periods of up to 36 months indicated that their risk of developing FIP decreased with time, suggesting the development of immunity rather than increased susceptibility to disease. In addition, of 56 cats deemed to have been naturally reinfected because their anti-FCoV antibody titers decreased and subsequently increased, only 3 developed FIP.

Carprofen (CPF) enantiomers and their glucuronide conjugates (GLUC) were measured in plasma and bile of horses after IV administration of the racemic compound (0.7 mg/kg of body weight). The CPF was detectable in plasma for up to 72 hours after dosing, whereas GLUC appeared early (time for maximal plasma concentration, 1 hour) and was measurable transiently at low concentration (maximal plasma concentration, 0.5 micrograms/ml). The enantiospecific plasma profiles indicated a clear predominance of R-CPF, whereas the stereoselectivity of the glucuronides favored S-GLUC. At 1, 2, and 12 hours after administration of the drug, bile concentrations of GLUC were high compared with those in plasma and enantioselectivity favored S-GLUC. These data indicate that the higher body clearance observed for S-CPF is a consequence of the enantioselectivity in liver glucuronidation and subsequent biliary excretion of the S enantiomer of the drug.

Newborn foals of mares grazing on Acremonium coenophialum-infected fescue pasture throughout gestation or from gestation day 300 to parturition had increased gestation duration and decreased serum triiodothyronine concentration. Pregnant mares were allotted to 4 treatments: grazing continuously on endophyte-free (E-) fescue, grazing continuously on endophyte-infected (E+) fescue, grazing on E+ fescue from gestation day 300 to parturition, and grazing on E+ fescue from conception to gestation day 300. Morphometric studies indicated that foals born to mares exposed to endophyte late in gestation had large, distended thyroid follicles lined by flat cuboidal epithelial cells. Mean triiodothyronine concentration in foals exposed to endophyte (395.2 ng/dl) was decreased (P < 0.01), compared with mean values in control foals (778.0 ng/dl). Thyroxine and reverse triiodothyronine concentrations were not significantly different among groups. Foal organ weight as a percentage of foal body weight was not significantly different among experimental groups.

Results of radiologic and anatomic studies of each cubital articulation (elbow) of a group of 50 adult cat cadavers indicated that a sesamoid bone may be located in a constantly present sesamoid cartilage associated with the tendon of origin of the supinator muscle. Radiography revealed a sesamoid bone in 40 of the 100 tendons of origin of the supinator muscles dissected from the elbows. The sesamoid bone articulated with the craniolateral aspect of the head of the radius, and the larger sesamoid cartilage, which contained the bone, articulated with the head of the radius and the capitulum of the humerus. Of several possible functions of the sesamoid cartilage (bone), it was considered that protection of the craniolateral part of the humeroradial articulation and maintenance of the complex anatomic system during joint movement were important. In radiographic views of the elbows of lame cats, the sesamoid bone should not be mistaken for a chip fracture or an osteocartilaginous loose body.