In an attempt to determine the best method for surgical removal of devitalized small colon lesions, 12 horses underwent a double small colon resection and end-to-end anastomosis. In 4 horses (study 1), an appositional single-layer (APP-1) suture pattern was compared with an inverting 2-layer (INV-2) suture pattern. In 8 horses (study 2), an appositional 2-layer (APP-2) suture pattern was compared with the INV-2 suture technique. Polydioxanone suture (size 1-0), was used. Horses were evaluated at necropsy 3, 10, 14, 28, or 56 days after surgery. Postoperative complications (peritonitis, impaction, or excessive adhesions) were encountered in 100, 42, and 13% of the APP-1, INV-2, and APP-2 anastomoses, respectively. Postmortem eva luation of the small colon revealed dehiscence of the anastomotic site, diffuse peritonitis, and adhesion formation in 3 of the 4 horses in which the resection line was closed with the APP-1 pattern. With the INV-2 and APP-2 techniques, more intestinal inversion was present in the nontaenial than in the taenial portion of the small colon. More postoperative impactions were found with the INV-2 (n = 5) anastomoses than with the APP-2 (n = 1) technique; this appeared to be the result of excessive tissue inversion. There was no difference in lumen diameter between the INV-2 and the APP-2 techniques (P greater than or equal to 0.05). However, horses with unresponsive impactions at the INV-2 site had a smaller luminal diameter compared with the INV-2 anastomoses that did not impact or that impacted and resolved with therapy (P less than or equal to 0.001). Difference in adhesion formation between the INV-2 and the APP-2 techniques was minimal. Bursting pressure studies (7 APP-2, 7 INV-2, and 14 control) were performed in study 2. All segments consistently burst away from the anastomotic site along the mesenteric or antimesenteric taenial band. Differences in bursting pressure (P greater than or equal to 0.05) were not evident between the 2 groups. Histologic evaluation revealed the APP-1 pattern had no intestinal inversion. However, a wide full-thickness deposition of dense fibrous connective tissue in the submucosal and muscular layer was evident. The INV-2 and the APP-2 patternshad pronounced inversion of the anastomotic layers along the nontaenial portion of the anastomoses, with minimal deposition of fibrous connective tissue between the anastomotic layers. The inversion formed a protruding ridge into the lumen that was more pronounced in the INV-2 than in the APP-2 anastomoses. At 28 days, the inverted tissues were held firmly together by maturing fibrous connective tissue that was covered by a mucosal layer. The inverted tissues were as pronounced at 56 days as they were at 3 days. In light of these findings, we concluded that an APP-2 pattern was the preferred surgical technique.

Three antigens were prepared from a type-3 avian strain of Pasteurella multocida, and their chemical and immunologic characteristics were studied. An antigen, designated 2.5S, was extracted with 2.5% NaCl solution and purified by chromatography. Lipopolysaccharide (LPS) was extracted with phenol-water, and a third antigen, designated FS, was extracted in 0.3% formalin solution containing 0.85% NaCl and purified by differential centrifugation. The 2.5S and the FS antigens consisted of 40% protein and 15% carbohydrate, whereas LPS did not contain a substantial amount of protein. A major protein component with a molecular weight of 44,000 was detected in the 2.5S antigen, as well as in the FS antigen. Of the 3 antigens, LPS had thehighest activity in mouse lethality and Limulus lysate tests. Antigenic cross-reactions among the 3 antigens were demonstrated by immunodiffusion tests. The 2.5S antigen was indistinguishable from the FS antigen, as both antigens contained the LPS component of approximately 45%. Treatments with various reagents indicated that the 2.5S and FS antigens contained at least 2 antigenic determinants. The first was a heat-stable protein sensitive to protease or phenol-water, and the second was a periodate-sensitive carbohydrate, which was an major antigenic determinant on the LPS antigen.

Morphologic lesions seen in six 8-month-old Labrador Retrievers with hereditary myopathy were predominantly small- and large-group atrophy of muscle cells of all fiber types. The dogs were intolerant of excerise and fatigued rapidly. An isolated gracilis muscle preparation was used to study the hemodynamic features of the microvasculature. Isogravimetric capillary pressure as well as arterial and venous pressures in the isolated gracilis muscle preparation obtained during maximal vasodilatation were within the range reported for healthy, mixed-breed dogs, as were precapillary, postcapillary, and total vascular resistances. Capillary filtration and osmotic reflection coefficients were not different from those reported in other studies on healthy dogs. All measurements and calculations were reported during reperfusion, subsequent to a 4-hour period of global ischemia. Postischemic vascular responses were similar to the pattern previously reported in healthy dogs. These studies did not support the hypothesis of a vascular defect as a cause of hereditary myopathy in Labrador Retrievers.

Epizootic hemorrhagic disease virus was isolated from cattle and sheep in northeastern Colorado during July and August 1984. The isolates were identified as serotype 2 by plaque-inhibition serotyping, genome electropherotyping, and protein analysis.

Ground reaction forces were measured from the hind limbs of 9 dogs before and after stabilization of unilateral cranial cruciate ligament rupture. Before surgery, peak vertical force, associated impulses, and weight distribution were significantly less (multivariate analysis P less than 0.02) in the affected limb, compared with the clinically normal limb. Craniocaudal peak forces and impulses, divided into braking and propulsion, also were significantly less in the affected limb. At a minimum of 7 months after retinacular imbrication, all vertical and craniocaudal measurements in the affected limb were increased significantly. Significant changes were not found in the normal limb. Furthermore, at the postoperative evaluation, there was no significant difference in any measurement between the affected and normal hind limbs. The results indicated restoration of function in the cruciate-deficient limb when compared with the clinically normal hind limb at a walking gait during the study time period.

Serologic virus neutralization tests, indirect immunofluorescence tests, and ELISA, using tissue culture-adapted feline infectious peritonitis virus (FIPV) or feline enteric coronavirus (FECV) were compared for their ability to distinguish specific virus exposure in cats. Sera of specific-pathogen-free cats inoculated with virulent or modified FIPV or FECV were used to compare the sensitivity and specificity of the homologous assays to a heterologous assay that measures antibody reactivity with transmissible gastroenteritis virus of swine. The geometric means of the serologic titers in FIPV and FECV assays were higher for FIPV- or FECV-infected specific-pathogen-free cats than the geometric means of the transmissible gastroente ritis virus assays for most groups. None of the assays was specific enough to discern the virus to which a cat had been exposed. However, the FIPV virus neutralization test appeared to be more sensitive for detection of an early response to FIPV infection than did the FIPV immunofluorescence test or FIPV-ELISA.

A commerical radioimmunoassay kit designed for measuring gastrin in human serum was validated for use with equine serum. This nonextraction, double-antibody procedure uses an antiserum with broad specificity for molecular forms of gastrin. Synthetic human gastrin (G17-I) was added to pooled equine serum, and the observed assay values were compared with the mass added. Recovery was 99 to 115% in the gastrin concentration range of 40 to 640 pg/ml. Dilutions of postprandial serum with serum from fasted horses were assayed, and the inhibition curves were compared with those of the human gastrin kit standards, using a log-logit transformation. The slopes of the sample dilution plots were not significantly different from the slopes ofthe standard curves. Ethylenediamine tetraacetate and heparin adversely affected the assay, resulting in lower assayed gastrin concentration values. The intra-assay coefficient of variation (n = 10) was 3.8%, and the interassay coefficient of variation (n = 6) was 11.2%. The assay sensitivity, as reported by the manufacturer, is 8 pg/ml. Gastrin concentrations in serum from fasted horses ranged from undetectable values (less than 8 pg/ml) to 17.5 pg/ml, and peaked at a mean value (n = 6) of 70 pg/ml 3 hours after feeding. Serum cortisol values monitored during the postprandial blood collection period were in the normal range for horses.

Strains of the suspensory ligament and deep digital flexor, superficial digital flexor, and long digital extensor tendons in the equine (pony) hind limb were recorded in vivo, using implanted strain gauges consisting of silicone rubber tubes filled with mercury. The relationship between strain gauge signals and tendon strains was obtained from tension-strain tests performed on isolated tendons after death of the ponies. During normal walking, maximal tendon strain (elongation over initial length, relative to the length of the structures at first ground contact) was 3.1% in the suspensory ligament and 3.4%, 2.3%, and 0.3% in the deep digital flexor, the superficial digital flexor, and the long digital extensor tendons, respectively. Changes (that occurred during walking) in the distance from origin to insertion of these musculotendinous structures were computed from limb geometric configuration and limb conformation. Maximal increase in origin to insertion length was 3.1% in the suspensory ligament and 2%, 1.6%, and 1.5% in the deep digital flexor, superficial digital flexor, and long digital extensor musculotendinous structures, respectively. The differences in strain, comparing the entire musculotendinous structure and its tendon, were explained by muscular contraction or relaxation.

An indirect immunoperoxidase staining technique was evaluated for detection of Mycoplasma hyopneumoniae in formalin-fixed, paraffin-embedded porcine lung. Lungs from swine with induced (n = 4) or naturally occurring M hyopneumoniae infection (n = 31) were examined grossly, by light and immunofluorescent microscopy, and by an indirect immunoperoxidase test, using antibody raised in swine against M hyopneumoniae as the primary antibody. Organisms stained by the indirect immunoperoxidase method were identified in tissue sections as pleomorphic brown-staining structures corresponding to those observed with immunofluorescence. Mycoplasma hyosynoviae, M hyorhinis, and Acholeplasma laidlawii did not stain with the indirect immunoperoxidase method, using antibody raised against M hyopneumoniae.

A study was undertaken to determine the toxic effects of cisplatin, an antineoplastic agent, on canine kidneys and bone marrow when administered during a 6-hour saline diuresis. Cisplatin (70 mg/m2 of body surface) was administered IV to 6 healthy dogs over a 20-minute period after 0.9% NaCl solution (saline) was administered IV for 4 hours at a rate of 18.3 ml/kg/hr. After cisplatin injection, saline diuresis was continued at the same rate for 2 hours. Each dog vomited within 8 hours after the drug was administered. Clinical status, weight gain, and food consumption were normal throughout the 27-day study. All measures of renal function remained unchanged and were within normal limits for 27 days after the drug was administered. Nadirs in the daily neutrophil count were observed on days 6 (3,240 +/- 404/microliter) and 15 (1,196 +/- 275/microliter). There were no important gross or histologic abnormalities referable to cisplatin administration when the dogs were necropsied at the conclusion of the study (day 27). We concluded that cisplatin can be administered safely at a dosage of 70 mg/m2 of body surface, using a shortterm diuresis protocol, and that the drug induces a ndair in the neutrophil count on days 6 and 15.