High-speed cinematography was used to record the movements of 12 cutting horses performing a standard test with a mechanical flag. Based on their previous competitive performances, horses were classified into 2 groups: group 1, composed of 5 moderately successful or average performers that had won less than $35,000 in purse money; and group 2, composed of 7 highly successful or elite performers that had amassed greater than $35,000 in competition earnings. Analysis of the results indicated that, compared with horses of the average group, the elite horses had faster reaction times in response to the start and cessation of flag movement (P less than 0.01), and were positioned closer to the flag during all stages of the trial (P less than 0.05). Discriminant analysis was used to construct a mathematical formula that could be used to classify an individual horse into 1 of the 2 alternative groups, based on the set of measurements. Two predictor variables were selected that described the maximal distance between the horse and the flag during the run and the part of the body that was moved first in response to the initial flag movement. The accuracy of the predicted group membership, compared with the actual group membership, was 100%.

The effect of aspirin on bovine platelet function and thromboxane A2 (TXA2) production in stimulated platelets was evaluated. A single dose of aspirin (100 mg/kg of body weight) was administered orally to Holstein cows, and blood samples were obtained before and at regular intervals for 7 days after treatment. The production of TXA2 was assessed by measuring the stable metabolite thromboxane B2, using a specific radioimmunoassay. Within 4 hours of aspirin administration, the production of TXA2 was significantly (P less than 0.05) decreased, irrespective of whether collagen, adenosine diphosphate, or platelet activating factor was used to initiate platelet aggregation. Despite the inhibition of TXA2 release from the stimulated platelets, platelet function, assessed by initial rate of aggregate formation and extent of aggregation, was unaffected by aspirin administration. The extent of aggregate formation in response to collagen, adenosine diphosphate, or platelet activating factor was independent of the amount of TXA2 released from platelets before and after aspirin treatment. The results suggested that TXA2 formation is not the primary biochemical pathway involved in the aggregation of stimulated bovine platelets.

Fifty-five dogs, naturally infected with Taenia sp or Dipylidium caninum or both, were assigned to the following treatment groups for dose titration studies with epsiprantel: nonmedicated control dogs (n = 14), medicated dogs given a dosage of 2.75 mg/kg of body weight (n = 15), medicated dogs given a dosage of 5.5 mg/kg (n = 16), and medicated dogs given a dosage of 8.25 mg/kg (n = 10). Medication was given orally in a tablet formulation. Feces were examined for cestodes passed and the gastrointestinal tract was examined at necropsy for retained cestodes. Efficacy of epsiprantel was 92.9% against Taenia and 44.8% against Dipylidium for a dosage of 2.75 mg/kg, 100% against Taenia and 99.8% against Dipylidium for a dosage of 5.5 mg/kg, and 94.6% against Taenia and 100% against Dipylidium for a dosage of 8.25 mg/kg. For dose confirmation, 36 dogs naturally infected with Taenia sp or D caninum or both were allotted to 2 treatment groups: nomedicated control dogs (n = 16) and dogs medicated with epsiprantel at a dosage of 5.5 mg/kg (n = 20). Efficacy was 100% for both Taenia sp and D caninum.

The ability of Mycoplasma hyopneumoniae to agglutinate RBC was evaluated to develop an in vitro cytadsorption assay. Using swine RBC in a microtitration hemagglutination test, no agglutination or partial agglutination was detected. Comparison of RBC from various other species indicated that improved hemagglutination was obtained with RBC from turkeys. This hemagglutination was detected only when mycoplasma cells used in the assay had been frozen and thawed, heated at 50 C for 30 minutes, or treated with trypsin. Treatment of RBC with trypsin or neuraminidase enhanced hemagglutination. Possible surface lectin activity in M hyopneumoniae was evaluated by use of carbohydrates in a blocking assay; hemagglutination was not inhibited by any of 13 carbohydrates evaluated. Mycoplasma hyopneumoniae convalescent porcine serum and monoclonal antibodies against 2 M hyopneumoniae immunogens of molecular weights of 64,000 and 41,000 inhibited hemagglutination.

The concentrations of serum amyloid A (SAA) in 4 cows given Escherichia coli endotoxin as an acute-phase stimulant were quantitatively evaluated by use of an indirect micro-ELISA method and compared with other clinical hematologic values. Serum amyloid A concentration changed minimally after intradermal infection of endotoxin. The concentration of SAA was increased 5 hours after IV injection of endotoxin, with maximal concentration after 17 to 20 hours. The increase in SAA concentration coincided with decreasing serum Zn and Fe concentrations; however, Zn and Fe concentrations appeared to be restored when SAA concentration was still maximal. It was concluded that the SAA response of cattle is comparable with that of other species and can be used for monitoring the activity of clinical inflammation and tissue injury.

Strips of trachealis muscle were dissected from the mid-cervical portion of the trachea of horses that were free of respiratory tract disease, and the overlying epithelium and mucosa were removed. Muscle strips were suspended in tissue baths that were filled with Krebs-bicarbonate solution, aerated with 5% CO2 in oxygen and maintained at 37 C. Isometric tension was continuously recorded. The increase in active isometric tension was concentration dependent when acetylcholine (10(-9) to 10(-4) M) or histamine (10(-9) to 10(-4) M) was added to the tissue baths in 0.5-logarithmic increments. When the tissues were contracted with acetylcholine (3.1 X 10(-6) M) or histamine (10(-4) M), the decrease in active isometric tension was concentration dependent when isoproterenol (10(-9) to 10(-4) M) or salbutamol (10(-9) to 10(-4) M) was added to the tissue baths in 0.5-logarithmic increments. There was no difference between the response to isoproterenol and salbutamol when tissues from the same horses were compared whether the tissues were contracted in response to acetylcholine (3.1 X 10(-6) M) or histamine (10(-4) M). Relaxation was antagonized by 10(-6) M) propranolol. The degree of relaxation obtained in these muscle strips was considerably less than that reported from other species' tracheal muscle strips that had the epithelium and mucosa intact. We concluded that equine tracheal smooth muscle contains beta-adrenoceptors that can be stimulated by either a mixed beta-1, beta-2 agonist or a selective beta-2 agonist.

In laboratory experiments, pseudorabies virus was readily recovered from within the body of houseflies (Musca domestica L) that had ingested the virus. Age of the fly and ambient temperature affected the rate of virus inactivation within the houseflies. Virus half-life in 3-day-old flies was 6.36 hours vs 2.81 hours in flies 8 or 13 days old. Half-life in 5-day old flies was 12.92 hours at 10 C, 5.95 hours at 20 C, and 2.69 hours at 30 C. Virus half-life in dead flies was 9.06 hours at 10 C, 4.28 hours at 20 C, and 1.71 hours at 30 C. The data did not provide any evidence of virus replication in either living or dead flies.

Subclinical Toxoplasma gondii infection was induced in young and adult cats by oral administration of tissue cysts. An antibody-capture ELISA to detect anti-Toxoplasma IgM-class antibodies in the serum of cats was developed. The serologic response to experimental infection was followed in the 2 groups of cats by use of anti-Toxoplasma IgM and IgG detection. This study shows that anti-Toxoplasma IgM-class antibody titers develop early in the course of experimental infection in cats and that the combination of IgM- and IgG-class antibody titer measurement can aid in the detection of recent subclinical toxoplasmosis.

We compared the ability of 3 alpha 2-adrenoreceptor antagonists, idazoxan (0.05 mg/kg), tolazoline (2 mg/kg), and yohimbine (0.2 mg/kg) to reverse xylazine (0.3 mg/kg)-induced respiratory changes and CNS depression in 6 ewes. Once weekly, each ewe was given a random IV treatment of xylazine, followed in 5 minutes by either an antagonist or 0.9% NaCl solution. Xylazine alone caused recumbency for 54.2 +/- 5.3 minutes (mean +/- SEM). Xylazine also increased respiratory rate and decreased PaCO2 for at least 45 minutes, but did not significantly change arterial pH or PaCO2. Idazoxan and tolazoline were equally effective in reversing the respiratory actions of xylazine; however, yohimbine was less effective in reducing the respiratory rate and was ineffective in antagonizing the decreased PaO2. Idazoxan and tolazoline decreased the duration of xylazine-induced recumbency to 6.3 +/- 0.6 and 9.5 +/- 2.3 minutes, respectively, whereas yohimbine did not significantly change this effect of xylazine. Thus, at the dosages studied, idazoxan and tolazoline appeared to be more effective than yohimbine in reversing the respiratory and CNS depressant actions of xylazine in sheep.

Affinity-purified bovine immunoglobulin isotypes were bacteriolytic for Pasteurella haemolytica biotype A, serotype 1 (PHA-1). This bacteriolysis was specific and complement-dependent. The IgM and IgG1 were the most active isotypes in the classic complement cascade. These isotypes also induced bacteriolysis through the alternative complement cascade. The comparative bacteriolytic activities of IgG1 and IgM were equal within each cascade; however, the bacteriolytic activities of IgG1 and IgM were equal within each cascade; however, the bacteriolytic activities of IgG1 and IgM were lower in the alternative cascade than in the classical cascade. The IgG2 was more bacteriolytic than IgA in the classic and alternative complement pathways. Bovine immunoglobulins passively protected C57BL/6 mice from experimentally induced pasteurellosis. There were no major differences in the protection among hyperimmune sera, purified IgM, or purified IgG. Mice were protected from PHA-1 by approximately 1.9 microgram of IgG and 1.2 or 0.1 microgram of IgM. Elimination of murine complement with cobra venom factor 3 reduced PHA-1 clearance in passively immunized C57BL/6 mice. The protective effect of IgM mediated resistance was highly dependent on an intact complement system. The intact complement cascade was associated with enhanced clearance of PHA-1 from the liver. Although PHA-1 was susceptible to antibody complement-mediated bacteriolysis in vitro, the dependence on an intact complement cascade was not absolute in experimentally induced murine septicemic pasteurellosis.