In Zimbabwe, ocular squamous cell carcinoma (OSCC) was frequently observed in 5 breeding herds of Simmental cattle, a Bos taurus breed originating from Switzerland. In these herds, initial signs of OSCC were already noticeable in cattle about 3 years old. Gradually, OSCC prevalence increased, and 36 to 53% of cattle over 7 years old had 1 or more tumors. More tumors developed in Simmental cattle with periorbital white skin than in cattle with periorbital pigmented skin. Other breeds of cattle (eg, Friesian) also are partly white-faced and live in Zimbabwe in a comparable environment; yet, OSCC prevalence was lower in those breeds.

A field trial was conducted on a commercial swine farm quarantined because of infection with pseudorabies virus. The purpose was to investigate, in growing pigs born to hyperimmunized sows, the immunogenicity of a vaccine with a glycoprotein I (gE) deletion. One hundred twenty pigs were assigned at random to 1 of 3 vaccination schedules at ages: 8 and 12 weeks; 8, 12, and 14 weeks; and 8, 12, and 16 weeks. Immune response was measured at 8, 12, 14, 16, and 18 weeks, using the serum neutralization test, a screening ELISA, and assays of IgG and IgA in serum and nasal secretions. Results of the serum neutralization test and the screening ELISA indicated that, for pigs vaccinated only at 8 and 12 weeks, the percentage of pigs with pseudorabies virus serum antibodies decreased substantially by 18 weeks; for pigs given a booster at 14 or 16 weeks, the prevalence of serum antibodies at 18 weeks was higher, with 16-week booster vaccination eliciting the best response. At each age, nasal IgA and IgG values were highly correlated (r greater than or equal to 0.70), as were serum IgA and IgG values; correlations of serum with nasal IgA and IgG values were somewhat lower (approx range, r = 0.40 to 0.70). Nevertheless, an increase in serum IgA or IgG values on vaccination was no guarantee of an increase in nasal IgA or IgG values. For serum and nasal mucosal antibodies, a poor immune response was associated with high quantities of maternally derived antibodies. Vaccination at 16 weeks was necessary to ensure eliciting of an immune response in almost all pigs.

A rapid subjective method for estimating the extent of gross pneumonia lesions in slaughtered pigs was compared with dissection of lungs in 51 slaughtered pigs. After standardization for prevalence in the regional industry, regression analysis indicated that the subjective method was highly predictive of the extent of pneumonic lesions (R2 = 0.88). Part of the error with the subjective method was attributed to approximations used for the relative proportions of lung lobes, which result in overestimation of the affected tissue by approximately 90%. Retrospective analysis of data from a slaughter monitoring program revealed strong associations (R2, 0.54 to 0.91) between prevalence, mean, median, and maximal lung scores in groups of pigs. Maximal lung score was biased by sample size, but prevalence and mean or median lung scores could be used to describe pneumonia severity in groups of pigs. Our results indicate that error in measurement of the extent of pneunomic tissue in slaughtered pigs is unimportant if the time of onset, clinical severity, and duration of disease are not quantified.

The partitioning of total pulmonary resistance (RL) into upper airway resistance and lower airway resistance (Rl) was studied in 8 Thoroughbred geldings. In addition, the phase shift and amplitude distortion of 3 catheters used for pressure measurements in this study were evaluated under static and dynamic conditions. Flow rate was obtained from a heated pneumotachograph attached to a tight-fitting mask placed over the nose. Electronic integration of the flow signal gave tidal volume. Transpulmonary pressure (PL) was obtained from calculation of the difference between the esophageal balloon catheter pressure and mask pressure. Lateral tracheal pressure was measured from a polyethylene catheter placed percutaneously in the middle portion of the trachea. Lower airway pressure (Pl) was calculated as the difference between esophageal pressure and lateral tracheal pressure. Similarly, upper airway pressure was defined as the difference between lateral tracheal pressure and mask pressure. Pressures are reported as the difference between the maximal and the minimal pressures recorded during a respiratory cycle. Airway resistance was calculated, using the isovolume method, at 50% of tidal volume. There were individual and group variations in Pl and Pl/PL, although P1 accounted for more than 60% of PL in all horses. In 6 horses, Rl was more than 50% of RL whereas in 2 horses, Rl was only 30 and 34% of RL. Amplitude distortion was minimal for the 3 catheters under static conditions in the in vitro study. Under dynamic conditions, amplitude distortion varied according to the catheter studied, the frequency, and the resistance of the system. There were no phase differences under static conditions at low frequency. However, phase discrepancy, which was variable through the cycle, was observed for some catheters at high frequency under static and dynamic conditions. It was concluded that, until measuring techniques are standardized in horses, variations in the partitioning of RL are likely to be obtained between studies and between animals within studies. However, phase discrepancy, which was variable through the cycle, was observed for some catheters at high frequency under static and dynamic conditions. It was concluded that, until measuring techniques are standardized in horses, variations in the partitioning of RL are likely to be obtained between studies and between animals within studies.

To determine whether abnormal airway pressures have a role in development of dorsal displacement of the soft palate (DDSP), measurements of tracheal and pharyngeal pressures were correlated with nasopharyngeal morphology in exercising horses. Exercising videoendoscopy and measurement of tracheal and pharyngeal pressures were used in 14 clinically normal horses and 19 horses with intermittent DDSP. The pressure signals were superimposed on the videoendoscope image, and both images were saved simultaneously on a videocassette for slow motion analysis to determine the instant displacement occurred in the respiratory cycle. Horses were submitted to an escalating 8-minute high-speed test with a maximal speed of 14 m/s. Compared with clinically normal horses, horses with intermittent DDSP did not have excessively negative inspiratory pressures during exercise. Eight horses displaced the soft palate during inspiration, 4 horses displaced it during expiration, and 7 displaced it by swallowing. Some horses displaced the soft palate at the beginning of the exercise trial, before reaching maximal speed, some horses displaced it at the peak speed, and some horses displaced it when slowing down. Epiglottic size in horses with DDSP was within normal limits, ruling out epiglottic hypoplasia as a cause of DDSP during exercise. Airway pressures were significantly (P < 0.002) altered after DDSP. Pharyngeal and tracheal inspiratory pressures were less negative, whereas pharyngeal expiratory pressure became less positive and tracheal expiratory pressure became more positive after displacement, suggesting a decrease in airflow and an increase in expiratory resistance in the upper airway.

A repeated-measures study was conducted on 5 dogs to clinically, radiographically, and echocardiographically characterize the actions of the angiotensin-converting enzyme inhibitor, enalapril, before and after development of experimentally induced heart failure. Heart failure was artificially induced, using a surgically implanted programmable ventricular pacemaker, which stimulated the heart at a rate of 245 beats/min until a low-output cardiomyopathic a state developed. This condition was then stabilized by decreasing the pacing rate to 190 beats/min. Pacing-induced heart failure was successfully induced in a mean +/- SD 4.2 +/- 1.95 weeks. The condition closely resembled the clinical, radiographic, and echocardiographic features of naturally acquired idiopathic dilated cardiomyopathy in dogs. Enalapril was well tolerated by dogs, and clinical adverse reactions did not develop. Results of echocardiographic studies indicated that enalapril treatment during the control period resulted in a significant (P < 0.05) increase in velocity of circumferential fiber shortening and a significant (P < 0.05) decrease in left ventricular ejection time. Therapeutic responses to enalapril were evident after development of heart failure. These included reduced severity of clinical signs of disease, evidence of decreased radiographically determined cardiac size (2 of 5 dogs), radiographic evidence of a reduction in pulmonary edema and congestion (4 of 5 dogs), significant (P < 0.05) reductions in left atrial and ventricular chamber dimensions (left atrial dimension, diastolic left ventricular internal dimension as determined echocardiographically), and improvement in some echocardiographic indices of left ventricular performance (velocity of circumferential fiber shortening and left ventricular ejection time).

Activities of diagnostically important enzymes were measured in serum and lysates of liver, kidney, skeletal muscle, heart, intestine, lung, and pancreatic tissues from wild-caught yellow rat snakes, Elaphe obsoleta quadrivitatta. All samples were analyzed for alkaline phosphatase, lactate dehydrogenase (LD), aspartate transaminase (AST), alanine transaminase, gamma-glutamyltransferase, and creatine kinase (CK) activities. The major enzyme activities found in the liver were LD and AST. The kidney had moderate activities of LD, AST, alanine transaminase, and CK. Skeletal muscle and heart contained high CK activity. Intestine, lung, and pancreas had low activities for most enzymes analyzed. Little to no gamma-glutamyltransferase activity was found in serum or tissues analyzed. Serum enzyme activities in yellow rat snakes were similar to those described for other reptile species, except for serum CK activity, which was increased in rat snakes.

A surgical technique was developed for implanting a flexible polyurethane cannula in a lateral ventricle in the brain of calves. Initially, measurements were made on 25 calves at necropsy to develop equations for calculating coordinates for cannula placement. The distance (cm) caudal, in the sagittal plane, from the coronal suture line to the center of a hole to be drilled in the parietal bone of the skull was: 0.73 + (0.00925 X body weight [kg]). The distance (cm) lateral from the midline to the center of the hole to be drilled was: 0.018 + (0.6464 X distance caudal). The depth (cm) from the surface of the skull to the dorsal surface of the lateral ventricle was: 2.29 + (0.0159 X body weight [kg]). Surgery was subsequently performed on 17 calves. A 5-mm-diameter hole was drilled through the skull with a hand trephine at coordinates derived from the aforementioned regression equations. A polyurethane cannula (total length, 30 cm; 1 mm ID; 2 mm OD) covering a stainless-steel 20-gauge blunt-tipped needle (stylet) was lowered through the brain and into a lateral ventricle at an angle of 20.5 degrees relative to the frontal bones of the skull. The blunt-tipped needle was then removed, and CSF was allowed to drip from the cannula to verify placement. One stainless-steel screw was inserted 0.6 cm medial, and another was inserted 0.6 cm caudal to the hole in the skull. The area around the cannula, bone screws, and hole in the skull was covered with dental acrylic (approx 2 cm in diameter) to stabilize the cannula. With minimal restraint of calves, injection of substances into and withdrawal of CSF from a lateral ventricle of the brain were possible in most calves for at least 6 weeks after surgery was performed.

The concentration of carbonic anhydrase III isoenzyme (cA-III) in serum samples from 216 clinically normal Thoroughbreds was determined by use of an enzyme immunoassay. The concentration range of cA-III was from 16.0 to 254.5 ng/ml (mean, 56.5 +/- 11.9 ng/ml). Significant differences were not detected according to age or sex. To confirm whether serum cA-III concentration was high in horses with muscle disease, serum samples of 11 horses with exertional rhabdomyolysis were analyzed by enzyme immunoassay. Their serum cA-III concentration was about 56 times (3,136 +/- 2,610 ng/ml) that of healthy Thoroughbreds. Concentration of cA-III was higher in horses with rhabdomyolysis that had been transiently recumbent than in horses with mild disease that were reluctant to move. Blood samples obtained serially from 6 horses with exertional rhabdomyolysis were studied. Serum activities of aldolase, creatine kinase, aspartate transaminase, and lactate dehydrogenase were high. Increases and decreases in concentration of cA-III were more rapid than that for aldolase, creatine kinase, aspartate transaminase, and lactate dehydrogenase activities; thus, cA-III may be clinically applicable as a diagnostic marker for muscle disease in horses.

Serum alpha-mannosidase activity and swainsonine concentration were determined in 4 cattle and 15 sheep (3 groups of 5 each) that were administered ground locoweed (Oxytropis sericea or Astragalus lentiginosus) containing swainsonine at dosages of approximately 0.8 mg/kg of body weight/d (cows, 30 days each) and 0, 1.0, and 1.5 mg/kg/d (sheep, 11 days each). The cattle developed mild clinical signs of locoism, including signs of depression, lethargy, and slight intention tremors. Clinical signs of toxicosis were not observed in the sheep. Within 24 hours of initial treatment, serum alpha-mannosidase activity in cows and sheep, measured by the release of 4-methylumbelliferone from an artificial substrate, was markedly decreased to 28 and 40 micromoles of 4-methylumbelliferone/L, respectively. Mean serum alpha-mannosidase activity of control cows and sheep was 400 +/- 94 and 422 +/- 42 (mean +/- SD), respectively. In the treated animals, decreased serum alpha-mannosidase activities returned to normal or higher activities within 6 days after treatment was discontinued. Using a jack bean alpha-mannosidase assay, increased swainsonine activity (153, 209, and 381 ng/ml, respectively) was detected in the serum of cattle and of sheep in the high- and low-dose groups within 24 hours after treatment with locoweed. Swainsonine concentration remained high, with mean concentrations of 204, 432, and 395 ng/ml (cows and 2 sheep groups, respectively) during the treatment period. After treatment, swainsonine was rapidly cleared, with estimated serum half-life of 16.4, 17.6, and 20.3 hours (cows, and high- and low-dose sheep groups, respectively). Significant differences in either alpha-mannosidase activity or swainsonine concentration were not detected between the 2 groups of treated sheep. These results suggest that serum alpha-mannosidase and swainsonine values are sensitive indicators of locoweed intoxication in cattle and sheep. Furthermore, it suggests that swainsonine is rapidly absorbed, resulting in rapid inhibition of serum alpha-mannosidase activity, leading to high serum swainsonine concentration. After exposure is eliminated, swainsonine is rapidly cleared from the serum, with serum alpha-mannosidase activity returning to normal values shortly thereafter.