Objective-To determine the effects of initial handling and training on autonomic nervous functions in young Thoroughbreds. Animals-63 healthy Thoroughbreds. Procedure-All horses were trained to be handled and initially ridden in September of the yearling year and then trained until the following April by conventional training regimens. To obtain the heart rate (HR), electrocardiograms were recorded in the stable before initial handling and training and following 7 months of training; variations in HR were then evaluated from the power spectrum in terms of the low frequency (LF; 0.01 to 0.07 Hz) power and high frequency (HF; 0.07 to 0.6 Hz) power as indices of autonomic nervous activity. To evaluate the fitness, the V200 (velocity at HR of 200 beat/min), which is reflective of the aerobic capacity of the horse, was measured. Results-Mean (+/- SE) resting HR decreased significantly from 41.5 +/- 0.8 to 38.7 +/- 0.4 beat/min following 7 months of training. The LF power of horses increased significantly from 1,037 +/- 128 milliseconds2 in September of the yearling year to 2,944 +/- 223 milliseconds2 in the following April. Similarly, the HF power increased significantly from 326 +/- 30 milliseconds2 to 576 +/- 39 milliseconds2 at the corresponding time points. The V200 increased significantly following training. Conclusions and Clinical Relevance-Increases in LF and HF powers indicate that parasympathetic nervous activity increases in horses by 7 months of training. The decrease in resting HR may be dependent on the training-induced increase of parasympathetic nervous activity in Thoroughbreds.

Objective-To evaluate whether immunosuppressive doses of cyclosporine (CsA) have an adverse effect on the liver, kidney, and pancreatic beta cells of pigs. Animals-8 juvenile 8-week-old Landrace X Large White crossbred pigs. Procedure-CsA (100 to 140 mg/kg) was administered orally to euglycemic pigs to reach whole blood trough concentrations of approximately 1500 ng/mL. To determine pancreatic beta cell function, plasma Cpeptide and insulin concentrations were measured in response to IV administration of glucose, glucagon, arginine, and oral administration of glucose. Effects on liver and kidney were determined by monitoring serum measurements of liver function and serum creatinine concentrations, respectively. Results-Plasma concentrations of C-peptide were significantly lower in euglycemic CsA-treated pigs, compared with control pigs, following IV administration of glucose, glucagon, arginine, and oral administration of glucose. Furthermore, the glucose clearance rate was decreased in euglycemic CsA-treated pigs, compared with control pigs. Serum creatinine concentrations and 4 of 7 serum measurements of liver function were not adversely affected by CsA administration. Serum concentrations of bilirubin and albumin were significantly increased, and serum alanine aminotransferase activity was significantly decreased in CsA-treated pigs, compared with control pigs. Histologic evaluation of liver and kidney sections revealed no pathologic findings in CsA-treated or control pigs. Conclusions and Clinical Relevance-In our study, immunosuppressive doses of CsA caused an impairment of porcine pancreatic beta cell function, but did not have toxic effects on the kidney. However, on the basis of changes in serum bilirubin and albumin concentrations and alanine aminotransferase activity, subclinical toxic effects on the liver did occur when immunosuppressive doses of CsA were administered.

Objective-To determine whether opioids with varying interactions at receptors induce a reduction in minimum alveolar concentration (MAC) of isoflurane in cats. Animals-12 healthy, female, spayed cats. Procedure-Cats were anesthetized with isoflurane and instrumented to allow collection of arterial blood and measurement of arterial blood pressure. Each drug was studied separately, and for each drug cats were randomly allocated to receive 2 doses. The drugs studied were morphine (0.1 or 1.0 mg/kg), butorphanol (0.08 or 0.8 mg/kg), buprenorphine (0.005 and 0.05 mg/kg), and U50488H (0.02 and 0.2 mg/kg). All drugs were diluted in 5 ml of saline (0.9% NaCl) solution and infused IV for 5 minutes. The MAC of isoflurane was determined in triplicate, the drug administered, and the MAC of isoflurane redetermined for a period of 3 hours. Results-All drugs had a significant effect on MAC over time. With morphine only, the effect on MAC over time was different between doses. The greatest mean (+/- SD) reductions in MAC of isoflurane in response to morphine, butorphanol, buprenorphine, and U50488H administration were 28 +/- 9, 19 +/- 3, 14 +/- 7, and 11 +/- 7%, respectively. Conclusions and Clinical Relevance-Morphine (1.0 mg/kg) and butorphanol (0.08 and 0.8 mg/kg) induced significant reductions in MAC of isoflurane that were considered clinically important. Although significant, reductions in MAC of isoflurane induced by morphine (0.1 mg/kg), buprenorphine (0.005 and 0.05 mg/kg), and U50488H (0.02 and 0.2 mg/kg) were not considered clinically relevant because they fell within the error of the measurement technique. Administration of morphine or butorphanol decreases the need for potent inhalant anesthetics in cats and could potentially be beneficial in combination with inhalants.

Objective-To compare renal clearance of technetium Tc 99m pentetate with plasma clearance by use of a glomerular filtration rate technique in pigs from 3 to 24 weeks of age. Animals-24 female pigs. Procedure-At the time of investigation, 5 pigs were 3 weeks old, 6 pigs were 6 weeks old, 8 pigs were 12 weeks old, and 5 pigs were 24 weeks old. Plasma clearance of technetium Tc 99m pentetate was measured by the use of a single injection technique followed by collection of multiple blood samples until 5 hours after the injection. Simultaneously, urine was collected through a urinary catheter, and the renal clearance of technetium Tc 99m pentetate was calculated. Results-Plasma clearance of technetium Tc 99m pentetate was correlated with the renal clearance ( r = 0.95). Plasma clearance was higher than renal clearance at all ages (mean, 5.8%), indicating extrarenal clearance of technetium Tc 99m pentetate or methodologic errors. Volume of distribution increased with increasing age but decreased as a fraction of body weight. Conclusions-Plasma clearance of technetium Tc 99m pentetate estimates renal clearance with acceptable precision when using single injection technique and multiple blood samples in pigs from 3 to 24 weeks of age.

Objective-To estimate sensitivity and specificity of 4 commonly used brucellosis screening tests in cattle and domestic water buffalo of Trinidad, and to compare test parameter estimates between cattle and water buffalo. Animals-391 cattle and 381 water buffalo. Procedure-4 Brucella-infected herds (2 cattle and 2 water buffalo) and 4 herds (2 of each species) considered to be brucellosis-free were selected. A minimum of 100 animals, or all animals > 1 year of age, were tested from each herd. Serum samples were evaluated for Brucella-specific antibodies by use of standard plate agglutination test (SPAT), card test (CT), buffered plate agglutination test (BPAT), and standard tube agglutination test (STAT). A Bayesian approach was used to estimate sensitivity and specificity of diagnostic tests without the use of a gold standard, assuming conditional independence of tests. Results-Sensitivity and specificity estimates in cattle, respectively, were SPAT, 66.7 and 98.9; CT, 72.7 and 99.6; BPAT, 88.1 and 98.1; and STAT, 80.2 and 99.3. Corresponding test estimates in water buffalo, respectively, were SPAT, 51.4 and 99.3; CT, 90.4 and 99.4; BPAT, 96.3 and 90.7; and STAT, 75.0 and 98.8. Sensitivity of the CT and specificity of the BPAT were different between cattle and water buffalo with at least 95% probability. Conclusions and Clinical Relevance-Brucellosis serologic test performance varied by species tested, but BPAT had the highest sensitivity for screening cattle and water buffalo. Sensitivity and specificity of more than 2 screening tests can be estimated simultaneously without a gold standard by use of Bayesian techniques.

Objective-To compare preoperative administration of meloxicam and butorphanol to perioperative administration of butorphanol alone for control of postoperative signs of pain in dogs. Animals-40 client-owned dogs scheduled for surgical repair of a cranial cruciate ligament rupture. Procedure-Group-1 dogs received butorphanol (0.2 mg/kg, IV) and meloxicam (0.2 mg/kg, IV) just prior to surgery. Group-2 dogs received butorphanol just prior to surgery (0.2 mg/kg, IV) and at incision closure (0.1 mg/kg, IV). Pain assessment began 1 to 2 hours before surgery and from extubation until 24 hours after surgery by obtaining the following measurements: the visual analog scale (VAS) score, cumulative pain score (CPS), adjusted cumulative pain score, modified cumulative pain score, and the adjusted modified cumulative pain score (AMCPS). Serum cortisol concentration was measured between 12 to 24 and between 1 to 2 hours prior to surgery, and at 30 minutes, and 1, 2, 4, 8, 18, and 24 hours after extubation. Results-No significant differences between treatment groups were observed in CPS or VAS score. At 8, 9, 10, and 11 hours after extubation, meloxicambutorphanol- treated dogs had a significantly lower AMCPS, compared with butorphanol-alone-treated dogs. Total serum cortisol concentration (area under the curve) during the measurement period was significantly lower in meloxicam-butorphanol-treated dogs, compared with butorphanol-alone treated dogs. Conclusions and Clinical Relevance-Preoperative single dose administration of meloxicam-butorphanol is equivalent to or slightly better than the administration of 2 perioperative doses of butorphanol for the control of postoperative signs of pain in dogs.

Objective-To evaluate the effect of prolonged water exposure on tissue mass and solutes of outer and inner layers of the stratum medium, sole, frog, and the stratum medium (SMZA) zona alba layer of horses' hooves. Specimen Population-10 hooves from 10 horses without foot abnormalities. Procedure-Hoof wall tissue specimens were obtained and immersed for 10 days in distilled deionized water. Serial changes in mass were recorded during the immersion period. Subsequently, osmolarity and Na+, K+, Cl-, and protein concentrations of the immersion solution were quantified. Results-Fully cornified outer hoof wall, sole, and frog epidermal structures increased in mass, whereas the SMZA lost mass when immersed in water. All hoof structures had a variable loss of crystalloids during immersion, but none of the specimens lost proteins. The frog epidermis was distinct in that total solute lost during immersion could not be ascribed to Na+, K+, and Cl-. Conclusions and Clinical Relevance-Data support a 2-compartment model for the fully cornified outer stratum medium, frog, and sole that permits the exchange of crystalloids, but not proteins, across the cell membrane and infers that topical agents containing proteins cannot benefit the hoof. The unique osmotic behavior of the SMZA relative to other hoof structures suggests the hypothesis that it is composed of transitional epithelial cells. The solutes lost from frog epithelium are interpreted to reflect its unique lipid composition.

Objective-To develop polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) analysis for molecular typing of strains of Streptococcus zooepidemicus and to use the new typing method to analyze a collection of isolates from the respiratory tract of Thoroughbreds. Sample Population-10 strains of S zooepidemicus, 65 isolates from the respiratory tract of 9 yearlings following long distance transportation, and 89 isolates from tracheal aspirates of 20 foals with pneumonia. Procedure-Phenotypic variations in the SzP protein were detected by western immunoblot analysis. Using PCR-RFLP analysis, genotypes were obtained with primer sets from the SzP gene, followed by restriction endonuclease digestion of the amplicons. Results-Unique genotypic patterns were obtained with a primer set designed from both ends of the structural gene and the restriction endonuclease Dde I. Forty-five isolates from the lymphoid tissue within the pharyngeal recess (ie, pharyngeal tonsil) of yearlings included 10 SzP genotypes and SzP phenotypes. Isolates from the trachea of each yearling were of a single genotype that was also present among isolates from the pharyngeal tonsil of the same horses. Isolates from tracheal aspirates of foals belonged to 14 genotypes. Conclusion and Clinical Relevance-Analysis of the SzP gene by use of PCR-RFLP was effective for molecular typing of strains of S zooepidemicus in the study of respiratory tract disease in horses. Results of PCR-RFLP analysis indicate that a single strain of S zooepidemicus can migrate from the pharyngeal tonsil to the trachea at a high rate in horses undergoing long distance transportation.

Objective-To determine plasma concentrations of adrenocorticotrophic hormone (ACTH) and alpha-melanocyte stimulating-hormone (α-MSH) in healthyferrets and ferrets with hyperadrenocorticism. Animals-16 healthy, neutered, privately owned ferrets, 28 healthy laboratory ferrets (21 sexually intact and 7 neutered), and 28 ferrets with hyperadrenocorticism. Procedures-Healthy ferrets were used for determination of reference plasma concentrations of ACTH and alpha-MSH. Diagnosis of hyperadrenocorticism was made on the basis of history, clinical signs, urinary corticoid-to-creatinine ratios, ultrasonography of the adrenal glands, and macroscopic or microscopic evaluation of the adrenal glands. Blood samples were collected during isoflurane anesthesia. Plasma concentrations of ACTH and α-MSH were measured by radioimmunoassay. Results-Plasma concentrations of ACTH in 23 healthy neutered ferrets during the breeding season ranged from 4 to 145 ng/L (median, 50 ng/L). Plasma concentrations of α-MSH in 44 healthy neutered or sexually intact ferrets during the breeding season ranged from < 5 to 617 ng/L (median, 37 ng/L). Reference values (the central 95% of the values) for ACTH and α-MSH were 13 to 100 ng/L and 8 to 180 ng/L, respectively. Plasma concentrations of ACTH and α-MSH in ferrets with hyperadrenocorticism ranged from 1 to 265 ng/L (median, 45 ng/L) and 10 to 148 ng/L (median, 46 ng/L), respectively. These values were not significantly different from those of healthy ferrets. Plasma ACTH concentrations of sexually intact female ferrets in estrus were significantly higher than those of neutered females. Conclusions and Clinical Relevance-Ferrets with hyperadrenocorticism did not have detectable abnormalities in plasma concentrations of ACTH or α-MSH. The findings suggest that hyperadrenocorticism in ferrets is an ACTH and α-MSH-independent condition.

Objective-To determine the effect of caprine arthritis-encephalitis virus (CAEV) infection on expression of interleukin-16 (IL-16). Animals-6 goats experimentally infected with CAEV and 6 age-matched healthy uninfected control goats. Procedure-Peripheral blood mononuclear cells (PBMCs) and synovial membrane cells from infected and control goats cultured with or without phytohemagglutinin were analyzed for IL-16 mRNA by use of a reverse transcriptase-polymerase chain reaction assay with goat-specific primers, after cloning and sequencing of a 384-bp fragment of the goat IL-16 gene. Synovial fluid, serum, and culture supernatants of PBMCs and synovial cells of control and CAEV-infected goats were analyzed for IL-16 by use of an ELISA. Results-The 384-bp product was 86% homologous to the corresponding human IL-16 nucleotide sequence. Higher expression of IL-16 mRNA in PBMCs (unstimulated or stimulated with phytohemagglutinin) was detected in samples from CAEV-infected goats, compared with control goats, but the difference was not significant. Synovial membrane cells infected in vitro had higher expression than uninfected control cells. Higher IL-16 concentration was detected in synovial fluid, serum, and culture supernatants of PBMCs of infected goats than in samples from control goats. Conclusions and Clinical Relevance-Infection with CAEV increases expression of IL-16, a proinflammatory and chemotactic cytokine. This cytokine appears to be constitutively expressed at low concentrations in normal uninfected PBMCs and synovial membrane cells. Increased production of IL-16 in CAEV infection may partly be responsible for increased lymphoid cell infiltrations observed in arthritic joints and other tissues of CAEV-infected goats.