The effect of ingested epidermal growth factor (EGF) on the small intestinal mucosa of conventionally weaned pigs was determined. At 21 days of age, 39 pigs were randomly distributed into suckling and weaned treatment groups that were administered 124 micrograms of EGF, 372 micrograms of EGF, or the dosing compound daily. Fecal water content was determined daily. On postweaning days 0, 3, 6, and 9, representative pigs from each group were euthanatized, and jejunal mucosa samples were collected for determination of villus-to-crypt ratio, total protein content, disaccharidase activities, and microbiological populations. At postweaning day 3, the 372-micrograms dose of EGF significantly (P less than or equal to 0.05) increased jejunal lactase and sucrase activities in the weaned pigs. Increased lactase activity was not greater than that of the suckling pig controls, whereas sucrase activity was significantly (P less than or equal to 0.05) higher than that of the suckling pig controls. Significant changes were not observed in villus-to-crypt ratio, mucosal protein content, or disaccharidase activities on other collection days.

Alterations in serum lipid and lipoprotein concentrations in ponies with experimentally induced liver disease were investigated. Hepatocellular damage was induced, using a nonlethal dose of carbon tetrachloride. In a separate group of ponies, obstructive jaundice was induced by surgical ligation of the common bile duct. Over a 6-day period, blood samples were obtained from ponies after treatment with carbon tetrachloride and for 12 days in ponies subjected to surgery. Serum cholesterol and triglyceride concentrations were unaffected in both groups of ponies, except for significantly (P < 0.01) high triglyceride concentration in ponies of the ligated group during the second postsurgical week. This increase was most likely attributable to anorexia observed during that period. Hyperbilirubinemia was observed early in ponies of the ligated group; most of the bilirubin was of the conjugated type. Using electrophoretic and ultracentrifugal methods, serum lipoprotein alterations were detected only in ponies of the ligated group. Increases of very low-density and low-density hpoprotein cholesterol concentrations and decrease in high-density lipoprotein cholesterol concentration were found. Although no changes were seen in total serum cholesterol concentration, a redistribution of lipoprotein cholesterol was observed in ponies of the ligated group. Similar alterations in lipoprotein distribution have been found in dogs, rats, and human beings with obstructive jaundice and cholestasis. The association between serum lecithin:cholesterol acyl transferase activities and these lipoprotein alterations remains to be elucidated.

Eleven adult goats and 32 adult outbred mice were inoculated IV with Cowdria ruminantium-infected blood (Kwanyanga isolate), monitored clinically, then serially euthanatized. Predominant clinical signs of disease in goats were depression, head tremors, seizures, and dyspnea. In mice, dyspnea and depression were the only clinical signs of disease noticed. Tissues were examined histologically and immunohistochemically for C ruminantium colonies or antigen. In goats, C ruminantium was detected only in endothelial cells of the brain, even though gross and microscopic lesions were confined to the thorax. In mice, C ruminantium was detected only in endothelial cells of the heart and lungs.

Sonographic and/or anatomic observations were made of the spleen in 27 dogs. Anatomic studies were used to establish precise correlations between the gross anatomic features of the organ and its ultrasonographic image. In 8 anesthetized dogs, ultrasonographic images of the spleen were made in dorsal, transverse, and sagittal planes. When it was incident to the ultrasonic beam, the splenic capsule was represented by a fine echogenic line that defined the boundaries of the organ. The splenic substance had a uniformly mottled echogenicity apart from the anechoic lumen of the splenic venous rami, which were detected at and near the hilus of the spleen. Less regularly, splenic arterial rami were detected at the hilus, but not within the splenic substance. Dorsal and transverse images were made with the ultrasonic transducer perpendicular to the left thoracic and abdominal wall at the 11th intercostal space and caudoventrad to it. Sagittal images were produced with the transducer's face directed craniad, placed parallel to the left lateral abdominal wall, and pushed under the costal arch. The adoption of such an ultrasonographic imaging protocol ensures that all of the spleen is inspected. A definitive opinion can then be given as to whether the spleen is normal or abnormal. Pathologic changes in the spleen must also be differentiated from changes in adjacent organs or structures.

In an attempt to ablate the laryngeal saccule as an alternative method of sacculectomy (conventially done through a laryngotomy incision for laryngeal hemiplegia) a neodymium:yttrium aluminum garnet laser was used transendoscopically in noncontact fashion in 6 horses. The procedure was easy, quick, and labor-saving, with few complications. Endoscopically, the lased sacculectomy site appeared healed at postsurgical day 42. On postsurgical day 42, microscopic examination revealed mucosal remnants under the granulation bed. Laser energy caused thermal damage to tissues adjacent to the lased saccule. Additional work must be done to refine the technique before it can be recommended for clinical applications.

The infectivity and pathogenicity of selected bovine viral diarrhea virus (BVDV) isolates were determined in gnotobiotic, colostrum-deprived neonatal lambs. Five-day-old cesarean-derived gnotobiotic lambs were exposed to 1 of 10 BVDV isolates via aerosol suspension. These isolates were from tissues or secretions of calves or lambs affected with respiratory tract disease, weak neonatal calves, aborted bovine fetuses, or reference Singer or Draper BVDV. The pathogenicity of each isolate, relative to the others, was evaluated in lambs by measurement of the neutralizing antibody response, virus isolation from nasal secretions or tissues, and postmortem lesions. The BVDV isolates varied in their infectivity and pathogenicity. Singer, the cytopathic reference strain, was the most lymphotrophic isolate and stimulated the greatest neutralizing antibody response. Encephalitis was the most consistent lesion observed and was used as the final determinant of relative pathogenicity of the viruses. The most neuropathogenic isolates were the 2 viruses originating from lambs affected with respiratory tract disease, the 2 weak neonatal calf isolates, and 1 isolate from an aborted bovine fetus. The least pathogenic isolates were the 2 reference isolates, Draper and Singer; the 2 mucosal disease isolates; and 1 isolate originating from an aborted bovine fetus.

The binding of bovine complement S protein (vitronectin) to Streptococcus dysgalactiae isolates from cattle with mastitis and the S protein's role in streptococcal adherence to bovine epithelial cells were investigated. All 25 clinical isolates of S dysgalactiae interacted with bovine S protein. None of the other streptococcal species tested bound to bovine S protein. The S protein-binding sites were saturable and highly sensitive to trypsin. The binding of bovine S protein to S dysgalactiae isolates was specific and could not be inhibited by other plasma proteins, such as fibronectin, albumin, fibrinogen, alpha 2-macroglobulin, or IgG. Similarly, streptococcal binding of bovine S protein was not influenced by the synthetic peptide Gly-Arg-Gly-Asp-Ser, which constituted the host cell attachment sequence of S protein. In adherence experiments, prior binding of bovine S protein to S dysgalactiae enhanced streptococcal adherence to bovine epithelial cells. The enhancing effects by bovine S protein were abolished when the respective binding sites on the streptococci were digested by trypsin. Thus, bovine S protein could be an important mediator of adherence of S dysgalactiae to bovine epithelial cells.

The effects of furosemide on the racing times of 79 horses without exercise-induced pulmonary hemorrhage (EIPH) and 52 horses with EIPH were investigated. Racing times were adjusted to 1-mile equivalent racing times by 2 speed handicapping methods, and analysis of covariance was used to adjust actual racing times by winning time and distance for each race. All 3 methods of determining racing time indicated that geldings without EIPH had significantly faster racing times (P < 0.05) when given furosemide before racing than when furosemide was not given before racing. Females and colts without EIPH were determined to have faster racing times when furosemide was given before racing, but the difference was not significant. Geldings with EIPH had significantly faster racing times (P = 0.0231) when given furosemide before racing, as determined by one of the speed handicapping methods. There was a strong correlation (range 0.9314 to 0.9751) between the 1-mile equivalent racing times, as determined by the 2 speed handicapping methods for horses with and without EIPH. Furosemide failed to prevent the development of EIPH in many horses that were previously considered to be EIPH-negative. When given furosemide, 62 (25.3%) of 235 EIPH-negative horses were EIPH-positive after racing. Furosemide had questionable efficacy for prevention of EIPH in known EIPH-positive horses. Thirty-two (61.5%) of 52 EIPH-positive horses given furosemide before a race remained EIPH-positive after that race.

Atracurium besylate, a nondepolarizing neuromuscular blocking agent, was administered as an infusion to 8 anesthetized cats in which neuromuscular blockade was assessed, using the train-of-four response. Once 50% depression of the first-twitch (T1) response was achieved, the infusion was held constant for 60 minutes before being discontinued and the recovery time was determined. The time for recovery was recorded as the time for the train-of-four ratio (T4 ratio) to increase from 50% to 75%. After recovery, atracurium infusion was reinstituted and the cats were again maintained for 60 minutes at 50% depression. A single bolus of gentamicin sulfate (2.0 mg/kg of body weight) was administered IV, and the infusion was continued for another 60 minutes before it was discontinued and the time for recovery was recorded. Within 1 minute of gentamicin administration, the mean +/= SD T1 response decreased from 49 +/- 5% to 33 +/- 8% of baseline and the T4 ratio decreased from 28 +/- 19% to 14 +/- 11%. Peak effect occurred at 5 minutes, with a T1 response of 29 +/- 6% of baseline and a T4 ratio of 13 +/- 12%. By 60 minutes after gentamicin administration, the T1 response had increased to 38 +/- 7% of baseline and the T4 ratio had increased to 21 +/- 13%. The time for recovery significantly (P less than 0.03) increased from 9.9 +/- 3.4 minutes during the control study to 18.1 +/- 10.7 minutes during the gentamicin study. In this study, gentamicin potentiated the neuromuscular blockade induced by atracurium and increased the recovery time. Residual blockade, observed after gentamicin administration was reversed with edrophonium.

Latency and reactivation of pseudorabies virus in swine was studied. Thirty-one pigs were assigned to 5 groups and were given 1 of 4 vaccines; 10 remained unvaccinated controls. All pigs were then challenge exposed with a sublethal dose of virulent pseudorabies virus. One hundred one days after challenge exposure, all pigs were treated with dexamethasone to reactivate the virus. Virus-positive tonsil and nasal mucus isolates were recovered from 29 of the 31 pigs over a 12-day period. Frequency and duration of virus-positivity were significantly (P < 0.05) and consistently lower among vaccinated pigs than among the unvaccinated controls. It was concluded that vaccination before challenge exposure had little or no effect on the rate of establishment of virus latency, but that vaccination reduced shedding after subsequent reactivation of the virus.