A technique for transvenous endomyocardial biopsy of the right ventricle was developed and evaluated for safety and efficacy in anesthetized healthy cats positioned in left lateral recumbency. At least 6 endomyocardial biopsy specimens were obtained from the right ventricle or interventricular septum of 11 cats. In 4 cats, the right jugular vein was torn during attempts to pass the introducing catheter into the right ventricle; however, in only 1 cat did this preclude catheter passage. This cat's heart was biopsied via the left jugular vein. Except for damage to the jugular vein, complications were infrequent, and the biopsy procedure was well tolerated by all cats.

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.

Lactase, maltase, sucrase, and alkaline phosphatase activities were determined in the intestinal mucosa from 3 locations in the small intestine and 4 locations in the large intestine 1 year after extensive large-colon resection (group 1; n = 5) and 1 year after sham operation (group 2; n = 3) in horses. Lactase, maltase, and sucrase activities were similar (P > 0.05) between group-1 and group-2 horses in all locations measured in the intestinal tract. Alkaline phosphatase activity in the remaining large colon of group-1 horses was significantly (P < 0.05) greater than the activity in the large colon of group-2 horses. Decreased apparent digestion of phosphorus and a negative phosphorus balance are persistent features of large-colon resection in horses. Increases in alkaline phosphatase activity in the remaining colon of horses with extensive large-colon resection may be a specific functional adaptive mechanism that attempts to counteract the derangements in phosphorus metabolism.

Fifty-four neonatal pigs were allotted to 4 groups and reared in an electrically controlled automatic feeding device (autosow). Each group was reared on a different pool of bovine colostrum: fresh, stored 1 month, stored 6 months, and stored 8 years. Bovine and porcine immunoglobulins in the sera of these pigs, and in a group of conventionally reared pigs, were measured periodically during the first 42 days after birth. The maximal concentration of absorbed bovine immunoglobulin was reached between 12 and 18 hours and equaled or exceeded the amount of porcine immunoglobulin absorbed by the conventionally reared pigs. Large differences in the concentrations of the bovine immunoglobulin isotypes among the various pools of colostrum were positively correlated with concentration of these isotypes in the sera of the neonatal pigs fed these pools. Relative to their concentrations in colostrum, approximately 41% of the IgG1, 55% of the IgG2, 29% of the IgM, and 67% of the IgA was absorbed. The IgA was absorbed the best and IgM was least absorbed. Significant trends or differences in absorption were not observed among groups. Neonatal pigs given fresh colostrum, which had a higher fat content, had significantly more weight gain (P < 0.05). This occurred, despite the fact that the fresh colostrum had the lowest concentration of bovine immunoglobulin. Serum half-lives for bovine IgG1 and IgG2 were significantly less than for porcine IgG (P < 0.05), whereas the half-lives for bovine and porcine IgM and IgA were similar. De novo-synthesized immunoglobulins were detectable in serum after 6 days; IgM concentrations reached a maximum at 15 days in neonatal pigs given stored, but not fresh, colostrum. The IgG and IgA concentrations steadily increased in all groups and were highest on day 42, when the study was terminated. Neonatal pigs ingesting fresh colostrum had significantly lower concentrations of de novo-synthesized IgG and IgA than pigs fed stored colostrum (P < 0.05). Concentrations in these pigs were also lower than those in conventionally reared pigs. This occurred, despite the lower immunoglobulin concentration in fresh colostrum, and correspondingly, the lower amount of bovine immunoglobulin in pigs that received this colostrum and absorbed it into their serum. In most instances, the amounts of immunoglobulin of any isotype absorbed from stored colostrum and the amount of de novo-synthesized immunoglobulin present 6 weeks later, were inversely correlated. Data indicated that a storage-labile, nonimmunoglobulin factor, in bovine colostrum is able to suppress de novo IgG and IgA synthesis by neonatal pigs.

In a 4 x 4 crossover-design study, pharmacokinetic variables of 2 injectable formulations of netobimin (trisamine salt solution and zwitterion suspension) were compared after SC administration in calves at dosage of 12.5 mg/kg of body weight. Netobimin parent drug was rapidly absorbed, being detected between 0.25 and 12 hours after treatment, with maximal plasma drug concentration (Cmax) values of 2.20 +/- 1.03 micrograms/ml achieved at 0.75 +/- 0.19 hour (trisamine) and 1.37 +/- 0.59 micrograms/ml at 0.81 +/- 0. 18 hour (zwitterion). Netobimin area under the plasma concentration-time curve (AUC) was 7.59 +/- 3.11 micrograms.h/ml (trisamine) and 6.98 +/- 1.60 micrograms.h/ml (zwitterion). Elimination half-life (tl/2 beta) was 2.59 +/- 0.63 hours (trisamine) and 3.57 +/- 1.45 hours (zwitterion). Albendazole was not detected at any time. Albendazole sulfoxide was detected from 4 hours up to 20 hours (trisamine) and from 6 hours up to 24 hours (zwitterion) after administration of the drug. The Cmax values were 0.48 +/- 0.16 micrograms/ml and 0.46 +/- 0.26 micrograms/ml for trisamine and zwitterion formulations, respectively, achieved at time to peak drug concentration (Tmax) values of 9.50 +/- 1.41 hours (trisamine) and 11.30 +/- 1.04 hours (zwitterion). Albendazole sulfoxide AUC was 3.86 +/- 1.04 micrograms.h/ml (trisamine) and 4.40 +/- 3.24 micrograms.h/ml (zwitterion); tl/2 beta was 3.05 +/- 0.75 hours (trisamine) and 3.90 +/- 1.44 hours (zwitterion). Albendazole sulfone was detected from 4 (trisamine) or 6 hours (zwitterion) to 24 hours after treatment. The AUC was 6.98 +/- 1.60 micrograms.h/ml (trisamine) and 10.51 +/- 7.41 micrograms.h/ml (zwitterion); Cmax was 0.76 +/- 0.21 micrograms/ml at Tmax of 12.00 +/- 1.85 hours (trisamine) and 0.70 +/- 0.24 micrograms/ml at Tmax of 12.50 +/- 2.33 hours (zwitterion). Albendazole sulfone t1/2 beta was significantly (P < 0.05) longer for the zwitterion formulation (7.77 +/- 4.72 hours) than for the trisamine salt (2.87 +/- 0.61 hours). Albendazole sulfone AUC was higher than albendazole sulfoxide AUC, resulting in AUC ratio of 1.8 (trisamine) and 2.4 (zwitterion). The 2 formulations were not significantly different in terms of AUC or Tmax for netobimin and albendazole sulfone, AUC for albendazole sulfoxide, or tl/2 beta for netobimin and albendazole sulfoxide. It was concluded that the 2 netobimin injectable formulations were bioequivalent. Experimental phase had a significant effect on the AUC and Cmax for albendazole sulfoxide and on the Cmax for netobimin. One possible explanation for the differences between phases could be induction of liver microsomal enzymes by netobimin and its metabolites, resulting in increased rate of metabolism during phase 2 of the study.

Enzyme-linked immunosorbent assays were established to detect Breda virus antigen in feces and homologous antibodies of the IgG1, IgM, and IgA isotypes in serum. With the aid of solid-phase immune-electron microscopy, torovirions in fecal material were observed. The course of natural infection was studied in 10 sentinel calves that had been obtained from different farms, and housed together at 1 week of age. They were separated from other cattle until the age of 10 months. Up to the age of 4 months, all calves regularly excreted Breda virus in the feces. Irrespective of the existence of IgG1 isotype maternal antibodies, all calves had early IgM responses in serum, but lack of IgA seroconversion. In 7 calves, antibody titer decreased below detection, whereas 3 calves had an isotype switch, resulting in persistent IgG1 titer. After introduction into the dairy herd at 10 months of age, all calves had diarrhea, and shedding of Breda virus was observed in 8 of them. Seroconversion for all antibody isotypes was observed, indicating lack of mucosal memory. In contrast, coronavirus infection in the presence of maternal antibodies led to isotype switch in all calves but one, and a memory response was observed after introduction into the dairy herd.

Serologic evidence indicated that an episode of congenital abnormalities in sheep was caused by Cache Valley virus (CVV), a bunyavirus indigenous to the United States. To determine the teratogenic potential of CVV in sheep, fetuses were infected in utero between 27 and 54 days of gestation with an isolate (CK-102) obtained in 1987 from a sentinel sheep in San Angelo, Texas. The dams of these fetuses were euthanatized between 28 and 75 days after inoculation, and the fetuses were examined for malformations. Twenty-eight of 34 fetuses had congenital abnormalities, including arthrogryposis, hydranencephaly, mummification, reabsorption, and oligohydroamnion. Virus was isolated from the allantoic fluid of 11 of 17 fetuses euthanatized at less than 70 days of gestation. The virus-positive fetuses, which were all negative for CVV-neutralizing antibody, had lesions ranging from none to severe arthrogryposis and hydranencephaly. Virus was not recovered from the allantoic fluid of fetuses after 76 days' gestation when CVV-specific antibody could be detected in 5 of 8 fetuses examined. The 2 fetuses infected on days 50 and 54 of gestation appeared normal and 1 had antibody to CVV.

A successful attempt was made to mechanically transmit bovine leukosis virus (BLV) from a BLV-infected cow with a normal lymphocyte count to sheep by inoculation with horse fly (Tabanus abactor) mouthparts. After interrupted natural feeding, horse flies were anesthetized with CO2. Mouthparts were severed and pooled into a tissue grinder containing medium. Five inocula containing the mouthparts of 10 flies each, and 5 inocula containing the mouthparts of 20 flies each, were prepared and inoculated SC in the right axilla of 10 BLV antibody-negative sheep. Five additional sheep served as controls. Serum samples were collected at 2-week intervals and tested by agar gel immunodiffusion for BLV antibodies. One sheep injected with 20 mouthparts developed antibodies to BLV at 10 weeks after inoculation. Six months after inoculation with fly mouthparts, 1 BLV antibody-negative sheep was randomly selected from each treatment group and injected, in the left axilla, with 3 ml of blood from the donor cow to confirm susceptibility of the sheep. All 3 sheep developed antibodies to BLV within 4 weeks.

The response of blood neutrophils to the chemotactic peptide formyl-methyl-leucyl-phenylalanine varies among species. Our results indicate that this peptide does not activate the respiratory burst of porcine neutrophils. Specifically, concentrations less than or equal to 10-6M did not cause production of either superoxide or hydrogen peroxide. Studies designed to delineate the biochemical deficit responsible for these results indicated that these cells do not express specific chemotactic peptide receptors on the external surface of the plasma membrane. Although these data do not rule out the possibility that internal stores of chemotactic peptide receptor exist, attempts to induce expression of the receptor by priming the cells with either lipopolysaccharide or calcium ionophore were unsuccessful.

Immunoturbidimetric determination of serum IgG concentration in foals was compared with the reference methods of single radial immunodiffusion and serum protein electrophoresis. High positive correlations were discovered when the technique was compared with either of these reference methods. The zinc sulfate turbidity test for serum IgG estimation was also evaluated. Although a positive correlation was discovered when the latter method was compared with reference methods, it was not as strong as the correlation between reference methods and the immunoturbidimetric method. The immunoturbidimetric method used in this study is specific and precise for equine serum IgG determination. It is rapid and, thus, is advantageous when timely evaluation of critically ill foals is necessary. The technique should be adaptable to various spectrophotometers and microcomputers for widespread application in veterinary medicine.