Concentrations of serum thyroxine (T4) and 3,5,3'-triiodothyronine (T3) were determined after the administration of freshly reconstituted thyrotropin-releasing hormone (TRH), reconstituted TRH that had been previously frozen, or thyrotropin (TSH) to 10 mature dogs (6 Greyhounds and 4 mixed-breed dogs). Thyrotropin-releasing hormone (0.1 mg/kg) or TSH (5 U/dog) was administered IV; venous blood samples were collected before and 6 hours after administration of TRH or TSH. Concentrations of the T4 and T3 were similar (P > 0.05) in serum after administration of freshly reconstituted or previously frozen TRH, indicating that TRH can be frozen at -20 C for at least 1 week without a loss in potency. Concentrations of T4, but not T3, were higher after the administration of TSH than they were after the administration of TRH (P < 0.01). Concentrations of T4 increased at least 3-fold in all 10 dogs given TSH, whereas a 3-fold increase occurred in 7 of 10 dogs given freshly reconstituted or previously frozen TRH. Concentrations of T4 did not double in 1 dog given freshly reconstituted TRH and in 1 dog given previously frozen TRH. Concentrations of T3 doubled in 5 of 10, 2 of 10, and 5 of 10 dogs given TSH, freshly reconstituted TRH, or previously frozen TRH, respectively. Results suggested that concentrations of serum T4 are higher 6 hours after the administration of TSH than after administration of TRH, using dosage regimens of 5 U of TSH/dog or 0.1 mg of TRH/kg. Additionally, results suggested that Greyhounds have lower concentrations of serum T4 than do mixed-breed dogs, but Greyhounds tend to have higher concentrations of serum T3.

Cardiovascular effects (vasodilatation, hypotension) of morphine administration have been attributed to central actions and peripheral histamine release. In the study reported here, we compared plasma histamine (Hm) concentrations after morphine sulfate and oxymorphone HCl administration in conscious dogs. Five healthy adult dogs (mean body weight, 10.1 kg) were randomly administered morphine (2 mg/kg of body weight, IV or oxymorphone (0.2 mg/kg, IV) by a 5-second bolus injection at weekly intervals. Venous blood samples (5 ml) were collected from jugular veins before and at 1, 2, 5, 15, 30, and 60 minutes after drug administration. Behavioral changes were recorded. Plasma was analyzed by a radioenzymatic technique, using purified histamine N-methyltransferase as an enzyme catalyst (sensitivity of assay, 40 pg Hm/ml). Mean base-line Hm value for all dogs was 0.55 ng/ml. The mean Hm value was significantly higher (P < 0.05) than the base-line value at 1, 2, 5, 15, and 60 minutes after morphine administration (531.4, 251.0, 113.0, 31.5 and 1.0 ng of Hm/ml, respectively), but there were no significant increases in histamine values from base-line values at any time after oxymorphone administration. All dogs given morphine and 1 dog given oxymorphone showed excitatory behavior; 2 dogs given morphine and 3 dogs given oxymorphone salivated profusely.

Red blood cells from 6 Pygmy goats were determined to be significantly (P less than 0.01) more susceptible to osmotic lysis and mechanical stress than were RBC from 6 Toggenburg goats. Differences in RBC size and shape and adenosine 5'-triphosphate concentration between the 2 breeds were not significant. The differences observed in the in vitro tests may be attributable to differences in RBC membrane composition.

Using an avidin-biotin-peroxidase complex immunoperoxidase staining method, respiratory syncytial virus (RSV) antigen was demonstrated in glutaraldehyde-fixed, parraffin-processed lung sections from calves with induced RSV pneumonia. The virus also was detected in formalin-fixed, paraffin-processed lung sections from calves with naturally occurring RSV pneumonia. Specific immunoperoxidase staining was detected within the cytoplasm of epithelial cells and syncytia in small bronchi, bronchioli, and alveoli. Staining also was detected within exudates in airway lumina and in mononuclear and multinucleate cells within alveolar lumina. Optimal intensity of staining was achieved by proteolytic enzyme treatment of lung sections, using 0 .1% pronase and overnight incubation in diluted primary antiserum. The distribution of antigen had a close correlation with presence of lesions. Antigen-staining patterns were similar in lung tissue from calves with naturally occurring and induced RSV disease.

A subpopulation of purified, interepithelial lymphocytes from porcine small intestinal mucosa contained cytoplasmic granules. Toluidine blue staining revealed metachromatic granules in 13.64% (606/4,450) cells. The cells had scant organelles, a single large nucleus with obvious invagination of the nuclear membrane, and prominent chromatin. Each cell contained 1 to 10 cytoplasmic membrane-bound granules, 0.6 to 1.5 microns in diameter. These findings indicated that the granular mucosal lymphocytes are related morphologically to mucosal mast cells. The presence of serotonin in the granules, confirmed by the serotonin releasing test, provided functional evidence that granular mucosal lymphocytes are related to mucosal mast cells.

Neuromuscular and cardiovascular effects of atracurium, a nondepolarizing neuromuscular blocking agent, were evaluated in 10 halothane-anesthetized adult horses. Hind limb digital extensor tension (hoof twitch) was measured with a strain gauge to quantitate the muscle relaxant effects of atracurium. Response of facial muscles was compared with hoof twitch. Five injections of atracurium were given. Initial mean (+/- SEM) dosage of 0.07 +/- 0.01 mg of atracurium/kg of body weight caused 98.6 +/- 0.8% reduction of the preinjection hoof twitch. Subsequent dosages of 0.04 +/- 0.003 mg/kg induced a degree of relaxation similar to that induced by the initial dose. Duration of paralysis from maximal effect to 10% recovery of twitch was 12.2 +/- 1.5 minutes for the first injection. This was significantly (P less than 0.05) different from subsequent paralysis periods, which lasted approximately 7 miutes. The 10% to 75% recovery time after all injections was similar--approximately 16 minutes. The facial muscles were less affected objectively by atracurium than was the hind limb. Atracurium did not cause cardiovascular changes. When the hoof twitch had recovered to 95% of its tension before atracurium administation, 0.5 mg of edrophonium/kg, was given to antagonize neuromuscular blockage. Within 5 minutes of edrophonium administration, twitch tension exceeded that measured before atracurium administrations. Within 2 minutes of edrophonium administration blood pressure began to increase and continued to increase approximately 10 mm of Hg above the value measured before edrophonium administration. Heart rate was not affected by edrophonium. Other muscarinic side effects of edrophonium were not observed. Of the 10 horses, 9 had good, unremarkable recovery to standing position. One horse had a violent recovery period.

Twenty-five strains of Escherichia coli isolated from turkeys were characterized for their serum resistance and virulence. An in vitro bactericidal assay was used to determine the serum resistance of E coli. Virulence was determined by survival time after IV inoculation of each strain into 3-week-old turkeys. Serum-resistant E coli strains were generally found to be virulent for turkeys, whereas serum-sensitive E coli strains were avirulent. Of the 25 strains, 18 strains were placed in the 2 categories of serum-resistant/virulent and serum-sensitive/avirulent. Five strains were serum-resistant and avirulent, and 2 strains were serum-sensitive and virulent. Serum resistance appears to be an important determinant of virulence for E coli in turkeys; however, the requirement for other virulence factors, in addition to serum resistance, was suggested by the finding that 5 serum-resistant strains were avirulent in turkeys.

Foals with the Ca blood group antigen on their RBC were given colostrum with anti-Ca antibodies (6 foals) or colostrum without anti-Ca antibodies (6 foals). The PVC were determined at birth and 2, 4, and 6 days after birth for the foals in each group. Significant differences were not observed for the PCV between the 2 groups, indicating that foals were not adversely affected by ingesting colostrum with the anti-Ca antibody. Standardbred mares without the Aa blood group antigen were evaluated to determine whether production of anti-Ca antibodies influenced production of anti-Aa antibodies. Of 266 mares without the Aa antigen, 3 of 61 (5%) mares without the Ca blood group antigen produced anti-Aa antibodies and 43 of 205 (21%) with the Ca blood group antigen produced anti-Aa antibodies. These 2 groups of mares were significantly (p = 0.006) different; Ca-negative mares were less likely to produce antibodies to Aa than were mares with the Ca blood group antigen. This observation was consistent with a hypothesis of antibody-mediated immunosuppression of immune response to the As blood group antigen by antibodies to the Ca blood group antigen, ie, when a mare is exposed to her foal's RBC and already has antibodies to the Ca blood group antigen on the foal's RBC, then she is less likely to initiate an immune response to the Aa blood group antigen also on the foal's RBC.

Holstein cow 1 was examined because of skin fragility and delayed healing of skin wounds, which were markedly exacerbated around the time of parturition. A skin biopsy sample was obtained, and light microscopy revealed irregular deposition of thin collagen fibers in a dermal matrix. Although diffuse inflammation did not occur, the number of plump fibroblasts was increased. Electron microscopy revealed poor construction of collagen fibrils in the dermal matrix. Biochemical analysis of the dermis revealed a normal amount of collagen and uronic acid, but sodium dodecyl sulfate-polyacrylamide gel electrophoresis reveled an increased proportion of soluble alpha-, beta-, and gamma-collagen chains of normal molecular weights. Neither procollagen nor its intermediates devoid of amino- or carboxy-terminal extension peptide were observed. Dermal collagen from cow 1 was more soluble in a neutral salt solvent, 0.5M acetic acid, and the acid containing pepsin than was dermal collagen from healthy cow 2. The peptic digestion profile of dermis from cow 1 revealed a lowered degree of intermolecular cross-linking and destabilization of helical structure in the dermis collagen. The extrahelical peptic cleavage of collagen before cyanogen bromide digestion resulted in release of more fragments derived from carboxy-terminal part of alpha1 chains in dermis of cow 1 than in dermis of healthy cow 2.

A bovine herpesvirus-1 (BHV-1) isolate (FI) from an aborted fetus was used to infect 9 heifers at various stages of gestation. Two heifers were inoculated IV on postbreeding day (PBD) 1, 7, or 14, and 3 heifers were inoculated in the sixth month of pregnancy. Plasma progesterone assays were used to monitor corpus luteum function in heifers inoculated during early pregnancy. Low progesterone values and infertility were seen in the 2 heifers inoculated on PBD 1. Luteal function remained normal in heifers inoculated on PBD 7 or 14. These 4 heifers inoculated on PBD 7 or 14 carried their fetuses to term, and their calves were free of BHV-1 infection at birth. Three heifers inoculated during the sixth month of pregnancy also carried their fetuses to term. Two calves were born alive, and BHV-1 was not isolated from nasal swab samples of either calf; the third calf was stillborn. Virus was not isolated from the stillborn calf's tissues, but BHV-1 was isolated from the placenta. Lesions were not detected in several tissues examined by light microscopy, and BHV-1 antigen was not detected by immunohistochemical examination of paraffin sections. Restriction endonuclease analysis of viral DNA was used to compare the FI virus to other BHV-1 isolates (Colorado-1, Iowa, and K22). On the basis of restriction endonuclease analysis, the FI isolate should be classified as a type-2 (infectious pustular vulvovaginitis) virus, specifically subtype a.