An oral vitamin E absorption test used in human beings was modified for use in horses. The most appropriate techniques with which to measure gastrointestinal tract absorption of vitamin E (alpha-tocopherol) in horses weredeveloped. Vitamin E was administered orally, and serum values of alpha-tocopherol were measured by use ofhigh-performance liquid chromatography at 0, 3, 6, 9, 12, and 24 hours after vitamin E administration. Variables included comparison of 2 dosages (45 and 90 IU/kg of body weight), routes of administration, and absorption dynamics of 3 preparations of dl-alpha-tocopherol. Absorption of the 2 doses of dl-alpha-tocopherol acetate indicated a dose response; the area under the curve at 24 hours (AUC24) was 4.3 micrograms.h/ml for the 45-IU/kg dose and 32.2 micrograms.h/ml (P < 0.01) for the 90-IU/kg dose. Maximal absorption was apparent when vitamin E was naturally consumed in grain, compared with administration of identical preparations by stomach tube or paste. In the same horses, dl-alpha-tocopherol and dl-alpha-tocopherol acetate plus polyethylene glycol had statistically similar absorption curves and both had significantly greater AUC24, compared with dl-alpha-tocopherol acetate; values for the 3 compounds were 23.6, 25.8, and 12.6 micrograms.h/ml, respectively. The AUC24 varied betweenindividual horses, but time of peak value was consistently observed between 6 and 9 hours. On the basis of the data from this study, the recommended technique for performing the oral vitamin E absorption test in horses would be administration of 90 IU of the free form of dl-alpha-tocopherol/kg, mixed in 1 L of grain to horses from which food has been withheld for 12 hours, followed by allowing the horses ad libitum access to hay immediately after administration of the vitamin E. Three baseline serum alpha-tocopherol values should be obtained within 24 hours prior to the test, with the last sample being obtained just prior to administration of the test dose of vitamin E. Heparinized plasma also may be used for this testing procedure. alpha-Tocopherol concentration should be measured at 3, 6, 9, 12, and 24 hours after vitamin E administration.

Epidemiologic data were evaluated from all dogs admitted to the University of Minnesota, Veterinary Teaching Hospital (UMVTH) between June 1981 and November 1989. Of 69,890 admissions, 2,077 were Miniature Schnauzers. Uroliths were retrieved from 63 of the 2,077 Miniature Schnauzers admitted. In 20 of the 63 urolith episodes, calcium oxalate was the predominant mineral identified. By comparison, calcium oxalate uroliths were identified in only 56 of the remaining 67,813 non-Miniature Schnauzer canine admissions. The odds that uroliths from Miniature Schnauzers were composed of calcium oxalate was 11.8 times greater than for other canine breeds evaluated at the UMVTH (95% confidence interval = 6.8 to 20.1). Data also were evaluated from files of uroliths retrieved from dogs and submitted to the Minnesota Urolith Center for quantitative mineral analysis between June 1981 and November 1989. Of 3,930 uroliths analyzed, 615 (15.6%) uroliths were obtained from Miniature Schnauzers. Of the 615 uroliths, 175 (28.4%) were calcium oxalate. By comparison, only 550 (16.6%) of the remaining 3,315 from dogs of breeds other than Miniature Schnauzers were calcium oxalate. The odds that uroliths submitted for analysis were composed of calcium oxalate was 2 times greater for Miniature Schnauzers than for dogs of other breeds (95% confidence interval = 1.6 to 2.4). Calcium oxalate uroliths were retrieved more frequently in males than females. The risk for males developing calcium oxalate uroliths was > 3 times the risk for females in both groups of data evaluated. The mean age of all Miniature Schnauzers admitted to the UMVTH with calcium oxalate uroliths was 9 years. Calcium oxalate uroliths were not detected in Miniature Schnauzers younger than 1.7 years.

An ammonium sulfate-soluble fraction of Taenia hydatigena cyst fluid (ThFAS) was further evaluated for use in the immunodiagnosis of cysticercosis. Analysis of ThFAS by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and protein immunoblot analysis confirmed earlier reports of a highly specific, low molecular weight antigen in this preparation; in contrast, other components of ThFAS were shown to react nonspecifically. Antibodies against the < 12-kD diagnostic antigen were detected in sera from 10 cattle and 4 swine inoculated with metacestodes of T saginata and T solium, respectively, but not in animals inoculated with Fasciola hepatica, Trichinella spiralis, Brucella abortus, or Toxoplasma gondii, or in noninoculated controls. Isolation and immobilization of the < 12-kD antigen on a hydrophobic transfer membrane resulted in development of an unambiguous dipstick assay capable of correctly identifying fully developed (10-week) experimentally induced infections in cattle and swine. In addition, the dipstick assay was highly specific for diagnosis of the disease in human beings, and offers the potential of distinguishing between human clinical cases of cysticercosis and taeniasis. A similar reactive antigen of diagnostic potential was also identified and isolated from T crassiceps and T taeniaeformis cyst fluids.

A flow cytometric method was developed to perform differential leukocyte counts on bovine blood. Blood specimens from 50 healthy Holstein cows were analyzed by use of a flow cytometer. The method entailed diluting blood with phosphate-buffered, hypotonic saline solution containing acridine orange, and performing a step-wise, 3-parameter analysis on the bases of cell size, cellular granularity, and granulocyte fluorescence. Initially, proportions of monocytes, granulocytes, and lymphocytes were determined by creating appropriate windows on dot plots of cell size (determined by forward light scatter) vs cellular granularity (determined by the logarithm of side light scatter). Eosinophils were resolved by analysis of granulocytes as dot plots of logarithms of green vs red fluorescence ascribed to acridine orange. Proportions of eosinophils and neutrophils were computed from data so generated. Microclumps of platelets spuriously affected counts of some granulocytes, particularly eosinophils. Differential leukocyte counts determined by flow cytometry generally compared favorably with those obtained by use of the conventional microscopic method, using Wright-stained blood films. Mean neutrophil and eosinophil counts determined by the 2 methods did not differ significantly, but lymphocyte counts determined by flow cytometry were significantly higher than those determined by microscopy (P < 0.01). Correlation coefficients for counts of neutrophils, eosinophils, and lymphocytes determined by the 2 methods ranged from 0.519 to 0.833. Correlation between monocyte counts was low (r = 0.147), although mean monocyte counts determined by the 2 methods did not differ significantly. Total leukocyte counts determined by flow cytometry were significantly lower (P < 0.01) than counts determined by use of an automated cell counter; correlation between the 2 counts was low (r = 0.350).

The area of skin supplied by the afferent fibers in one cutaneous nerve is called the cutaneous area (CA) for that nerve. The CA of peripheral branches of lumbar and sacral spinal nerves responsive to the stimulation of hair follicle mechanoreceptors were mapped in 27 dogs. The amount of overlap among the CA was similar to that found for other CA of the body. The CA of peripheral branches of the sciatic nerve were restricted to the lateral, cranial, and caudal aspects of the pelvic limb distal to the stifle. The CA of the saphenous nerve was located on the medial side of the limb, except for a small area located on the lateral side of the crus. The distal part of the CA of the saphenous nerve was completely overlapped in the hind paw by branches of the superficial peroneal nerve laterally and the medial plantar branch of the tibial nerve medially. The CA for the deep peroneal nerve was located on the dorsal surface of the webbing between digits 2 and 3 and the adjacent skin of these digits. The CA of the plantar branches of the tibial nerve were small in comparison with the diameter of the nerve, suggesting that these branches contained nerve fibers supplying other, deeper structures in the hindpaw and that damage to these nerves would interfere with cutaneous sensation in only a small region on the plantar surface of the hindpaw. Knowledge of the CA of the various branches of the sciatic nerve allows more accurate localization of injury to the sciatic nerve or its branches by using areas of anesthesia.

The central arterial pharmacokinetics of alfentanil, a short-acting opioid agonist, were studied in rabbits, sheep, and dogs after short-duration infusion of the drug. Alfentanil was infused until a set end point (high-amplitude, slow-wave activity on the EEG) was reached. This required a larger alfentanil dose and a higher alfentanil arterial concentration in sheep, compared with rabbits and dogs. The plasma concentration-time data for each animal were fitted, using nonlinear regression, and in all animals, were best described by use of a triexponential function. In this study, differences in the disposition kinetics of alfentanil among the 3 species were found for only distribution clearance and initial distribution half-life. In dogs, compared with rabbits and sheep, the first distribution half-life was longer, probably because of pronounced drug-induced bradycardia (mean +/- SD, 48 +/- 21 beats/min). Distribution clearance was faster in sheep, compared with dogs, also probably because of better blood flow in sheep. Elimination half-life was similar in all species (rabbits, 62.4 +/- 11.3 minutes; sheep, 65.1 +/- 27.1 minutes; dogs, 58.3 +/- 10.3 minutes). This rapid half-life resulted from a small steady-state volume of distribution (rabbits, 908.3 +/- 269.0 ml/kg; sheep, 720.0 +/- 306.7 ml/kg; dogs, 597.7 +/- 290.2 ml/kg) and rapid systemic clearance (rabbits, 19.4 +/- 5.3 ml/min/kg; sheep, 13.3 +/- 3.0 ml/min/kg; dogs, 18.7 +/- 7.5 ml/min/kg). On the basis of these pharmacokinetic variables, alfentanil should have short duration of action in rabbits, sheep, and dogs. This may be beneficial in veterinary practice where rapid recovery would be expected after bolus administration for short procedures or after infusion for longer procedures.

Blood culture and serologic testing were used to study the prevalence of Trypanosoma cruzi infection in a group of 85 dogs from southern Louisiana rural environment. These dogs were known to have been in contact with wild mammalian hosts of the hemoflagellate. Results were compared with blood culture and serologic test results in 103 dogs from a rural environment and with limited known wild mammalian T cruzi host contact. Serologic test results for the 188 dogs from the rural environment were compared with results for 176 dogs from an urban animal shelter and for 100 household pet dogs from an urban southern Louisiana environment. Blood culture was not performed on urban dogs. Culture results were negative in all dogs from rural environments. Serologic evidence of infection was obtained for 4 of the 85 (4.7%) dogs of rural environment with known host contact. Of 176 dogs from the animal shelter, 4 (2.3%) had high antibody titer to T cruzi, and 11 others had low titer (< 2 adjusted ELISA units [aEU]). Two and 4 dogs of the housed urban and rural groups, respectively, had antibody titer to T cruzi that was < 2 aEU. Results indicate that prevalence for exposure to T cruzi antigen is higher in dogs with high potential contact with the vector and wild mammalian hosts of T cruzi, whether they are from rural or urban environment. Furthermore, results indicate that similar studies on high-risk human populations may be indicated.

Blood, feces, nasal secretions, and tears werecollected weekly from 5 randomly selected 1- to 8-week-old calves in a large commercial dairy herd. Clinical signs and bovine coronavirus (BCV) shedding from the respiratory and enteric tracts of calves were monitored through the 8-week period by direct immunofluorescence of nasal epithelial cells, protein A-gold immunoelectron microscopy on feces, and ELISA on nasal secretions and feces. All samples were analyzed for antibody isotypes to BCV structural proteins by immunoblotting. All calves had BCV respiratory tract infections and 4 of 5 calves shed virus in feces. Several calves had multiple or prolonged periods of BCV respiratory tract or enteric tract shedding or both. All calves (except 1) had passive IgG1 antibodies to some BCV proteins (mainly the E2 and E3 proteins) in their serum when they were 1 week old. The presence of these passive serum antibodies (mainly to the E2 and E3 BCV proteins) was associated with decreased or delayed systemic and mucosal antibody responses in calves, in particular IgA responses in nasal secretions and tears to the E2 and E3 BCV proteins, but not to the N protein. Moderate amounts of maternal BCV E2- and E3-specific antibodies in serum did not prevent BCV enteric tract or respiratory tract infections in calves, but may have delayed the development of active antibody responses to these BCV proteins. However, calves with BCV respiratory tract or enteric tract infections had no detectable passive antibodies to any BCV proteins in nasal secretions or feces.

The beige (bgJ/bgJ) mouse is a well-described murine model of Chediak-Higashi syndrome. Platelet function was examined in normal and beige mice to better characterize the defective aggregation response in platelets from mice with Chediak-Higashi syndrome. Platelet aggregation after collagen, thrombin, and phorbol-12-myristate 13-acetate stimulation was significantly (P < 0.025) decreased in platelets from beige mice, relative to platelets from normal mice. Compared with beige and normal mice, those heterozygous for the bg trait had intermediate responses to collagen and thrombin, but not phorbol-12-myristate 13-acetate. The defect(s) in aggregation of platelets from beige mice was associated with a dense granule storage pool deficiency and decreased stores of serotonin and adenine nucleotides in platelets. Mice heterozygous for the bg trait had normal platelet serotonin and adenine nucleotide concentrations. Platelets from beige mice were approximately 10 times more sensitive to prostacyclin inhibition of collagen-induced aggregation than were platelets from control mice. However, a significant difference in platelet cyclic AMP concentration was not apparent between beige and normal mice after prostacyclin stimulation. Platelet endoperoxide synthesis measured by quantification of thromboxane B2, was normal in beige mice. Protein phosphorylation patterns in mouse platelets were similar to those seen in human platelets. Thrombin and collagen-induced [32P] phosphorylation of 40- and 20-kD proteins in platelets from normal and beige mice was similar. Results indicate that the biochemical defect(s) in platelet function in beige mice is partially attributable to storage pool deficiency and does not result in an absolute defect in phosphorylation of 40- and 20-kD proteins.

Two recently developed direct methods, radioassay-125I-labeled hyaluronic acid binding protein (125I-HABP)- and high-performance liquid chromatography (HPLC), were used to assess and compare the concentration of hyaluronate (HA) in synovial fluid of horses. Also determined were changes in the HA concentration in an experimental treatment model involving physiologic saline solution (PSS)-irrigated or methylprednisolone acetate-injected tarsocrural joints of clinically normal horses. Serum HA concentration was determined simultaneously, using the 125I-HABP assay. Synovial fluid HA concentration values obtained by use of the HPLC method were approximately double the values obtained by use of 125I-HABP assay. Correlation (r = 0.819) between the 2 methods was highly significant (P < 0.001; linear regression analysis) for all samples studied and for various experimental subgroups. When pure HA standards were used, correlation between the 2 methods was close to 1 (r = 0.965; P < 0.001), with higher values obtained by use of the 125I-HABP assay. It is suggested that the HA binding protein derived from endogenous cartilage proteoglycan interferes with the 125I-HABP assay on synovial fluid, resulting in excessively low values, compared with those obtained using the HPLC procedure. Intra-articular injection of methylprednisolone acetate significantly (P < 0.01) increased synovial fluid HA concentration at 24 hours after injection. Increase was also detected after PSS irrigation, but owing to wide intersubject variation, this increase was not significant. The HPLC procedure, which provides simultaneous information about the concentration and degree of polymerization of HA, is recommended for the study of synovial fluid, whereas the 125I-HABP assay is more suitable for serum HA analysis.