The effects of the corticosteroid 6-alpha-methylprednisolone acetate on normal equine articular cartilage were evaluated, using the middle carpal joint in 4 clinically normal young horses. One middle carpal joint of each horse was injected 3 times with 100 mg of 6-alpha-methylprednisolone acetate, at 14-day intervals. The opposite middle carpal joint (control) was injected with 2.5 ml of lactated Ringer solution at the same intervals. Effects were studied until 8 weeks after the first injection. Evaluation included clinical and radiographic examination, and gross, microscopic, and biochemical evaluation of joint tissues. Horses remained clinically normal during the study, and significant radiographic changes were not observed. Safranin-0 matrix staining intensity and uronic acid content were significantly (P < 0.05) lower and hydroxyproline content was significantly (P < 0.05) higher in articular cartilage of corticosteroid-injected joints vs control joints.

We developed a single-pedicle, axial pattern tubed skin flap that could be transferred to an in vitro perfusion apparatus. On the basis of results of prosections, angiography, contact radiography, and surviving-length studies, it was concluded that a single-pedicle, axial pattern skin flap measuring 4 cm X 12 cm incorporating the caudal superficial epigastric artery would survive to its entire length. Subsequently, a surgical (stage 1) procedure was developed for the routine preparation of single-pedicle, axial pattern tubed skin flaps. Healing after the stage-1 procedure was evaluated by visual inspection and fluorescein angiography. Stage-1 procedures were performed successfully 149 of 160 (93%) times. A second surgical (stage 2) procedure was developed for routine cannulation of the caudal superficial epigastric artery and harvest of the tubed skin flap. Stage-2 procedures were performed successfully 136 of 144 (94%) times.

In mammalian species studied previously, pepsinogen consisted of biochemically different groups of isozymogens. By use of gel filtration chromatography and electrophoresis, we isolated a predominant pepsinogen from the gastric mucosa of a horse. Peptide mapping with V8 protease revealed differences with its porcine homologue. However, porcine and equine pepsinogens, when activated to pepsin, had a similar pattern of activity when hemoglobin was used as substrate. Those results suggest that differences must exist in the primary structure of the pepsinogens of the 2 species.

In an attempt to establish if cross protection can be induced by different strains of Haemophilus parasuis, three groups of 12 gnotobiotic pigs were immunized each with an aluminum hydroxide adsorbed whole cell bacterin of one of three H. parasuis strains. Two weeks later, four pigs within each vaccinated group were challenged with aerosols of live cultures of each of the three test strains and observed for response. Two virulent strains V1 and V2 protected all the vaccinated pigs, while all non-vaccinated controls succumbed to Glasser's disease when challenged with these strains. Vaccination with strain LV (of low virulence) protected the pigs against challenge with strain V2, but not against strain V1. Strain LV did not cause disease in the immunized animals and only in one of ten nonimmunized pigs upon second challenge. The results suggest that strains may differ in antigenicity and that virulence and immunoprotection are positively related. Strains to be used in commercial vaccines should therefore be selected carefully. Antibodies detected in the sera of vaccinated pigs were to outer membrane proteins of the bacteria, but not to lipopolysaccharides or capsular polysaccharides. This would suggest that for gnotobiotic pigs outer membrane proteins are more immunogenic than lipopolysaccharide or capsular antigens. Further work is needed to determine if outer membrane proteins also contribute protective immunogens.

Inclusion of lactose in the diets of chickens has been determined to reduce cecal colonization with Salmonella typhimurium. We hypothesized, therefore, that dietary lactose may be a practical means for reducing the prevalence of Salmonella contamination of chicken products. Because some strains of Salmonella are atypical and ferment lactose, we investigated the effects of dietary lactose on cecal colonization with lactose-fermenting S typhimurium. Broiler chicks were inoculated intracloacally with Lac+ S typhimurium selected for resistance to novobiocin and rifampicin. The chicks also were inoculated orally with certain anaerobes that do not effectively inhibit colonization by S typhimurium, but do appear essential for lactose mediated inhibition of cecal colonization. Control chicks were not given dietary lactose, and chicks in the experimental group were fed a diet containing 7% lactose. Enumeration of Lac+ S typhimurium in cecal contents revealed dietary lactose to be effective at controlling this organism. Control was correlated with changes in cecal pH and increases in undissociated volatile fatty acids, especially propionic acid.

An experiment was conducted to determine whether a persistent Salmonella newport infection could be established in swine, to determine duration of shedding and distribution of the organism in internal organs, and to determine whether changes occurred in antimicrobial susceptibility or plasmid profile of the organism during the course of long-term infection. Naturally farrowedSalmonella-free pigs (n = 22) were orally exposed to a multiply antimicrobial-resistant zoonotic strain of S newport when they were 7 weeks old. Tonsillar and rectal swab specimens were examined bacteriologically for S newport during the first week after exposure, then weekly for 7 weeks. Fecal samples were likewise examined weekly or every 2 weeks for 28 weeks after exposure. Necropsies of 2 or 3 randomly selected pigs were conducted at 2, 4, 8, 12, 16, 20, 24, and 28 weeks after exposure. A total of 45 specimens/pig representing the following internal organs or tissues were examined bacteriologically for S newport: liver, spleen, kidney, gallbladder, heart, heart blood, lung, stomach, and tonsils; segments of the intestinal tract with corresponding lymph nodes; and lymph nodes from lymphocenters of the head and neck, thoracic cavity, thoracic limbs, abdominal viscera, and abdominal wall. Exposure to S newport induced a mild and transient clinical response. The organism was recovered from 97% of tonsillar swab specimens and 89% of rectal swab specimens collected during 7 weeks after exposure and from 98% of fecal samples collected during 28 weeks after exposure. At necropsy, S newport was recovered most frequently from tonsils (86.4%), followed by segments of the intestinal tract from ileum to rectum (81.8% recovery from cecal contents), and from mandibular (68.2%), jejunal (50%), and ileocolic (45.5%) lymph nodes. Sporadic recoveries of the organism were made from other lymph nodes and from gallbladder, stomach, kidney, spleen, liver, and heart, varying from 2 to 20 weeks after exposure. The cranial portion of jejunum, medial iliac lymph nodes, dorsal superficial cervical lymph node, and heart blood of all pigs were culture-negative. Of 26 representative isolates of S newport recovered from body organs or feces during 28 weeks after exposure, 4 (15.4%) underwent changes in antimicrobial susceptibility pattern. Changes in plasmid profile of the organism were not detected during longterm infection of swine.

Several investigators have suggested that the conventional multicompartmental exponential analysis of in vivo glucose metabolism is arbitrary and possibly not the most accurate description of glucose kinetics, especially in the large animal. In support of that hypothesis, we found that in a systematic comparison of 3 methods, blood-specific radioactivity data in single-injection studies of glucose metabolism in lactating cows was better described graphically, or by a hybrid polynomial-biexponential curve fit, than by an exclusively exponential curve fit. We hypothesized that this finding was attributable to partial failure of linearity and steady-state assumptions that underlie the exponential model. Second, using both an irreversible tracer (3H-labeled glucose) and reversible tracer (14C-labeled glucose), we found that glucose carbon recycling had no effect during the first 2 hours, but became significant in lactating cows 7 hours after injection. Finally, we determined that approximately 52 to 55% of the glucose replacement rate was being used to generate lactose.

Six calves with suppurative arthritis were given a single IM injection of sodium cephapirin at a dosage of 10 mg/kg of body weight. Cephapirin concentrations were serially measured in serum and in normal and suppurative synovial fluid over a 24-hour period. Mean peak serum concentration was 6.33 microliter/ml at 20 minutes after injection. The highest cephapirin concentrations in normal and suppurative synovial fluid were 1.68 and 1.96 microgram/ml, respectively, 30 minutes after injection. Overall mean cephapirin concentration in normal synovial fluid for the first 4 hours (1.04 +/- 0.612 microgram/ml) was not significantly different from that in suppurative synovial fluid (0.88 +/- 0.495 microgram/ml; P > 0.05). Elimination half-life was 0.60 hours and clearance was 1,593 ml/h/kg.

An indirect immunoperoxidase staining technique (IP) is described for the detection of bovine viral diarrhea virus (BVDV) in bovine semen. The performance of the IP was compared to the reference immunofluorescent staining test in its ability to detect BVDV in 23 coded field semen samples. The IP assay which can be applied with ease to a large number of samples and does not require expensive fluorescence microscope equipment, appears to be an alternative method for BVDV detection. The IP assay can be strongly recommended for certification of BVDV-free bovine semen for artificial insemination and trading purposes and for laboratories which are not equipped for performing the immunofluorescent test.

Three trials were conducted to establish if young primary specific pathogen free (SPF) pigs could be protected from Glasser's disease by vaccination. Three age groups of cesarean-derived isolator-reared gnotobiotic pigs were vaccinated twice at 4 and 6, 3 and 5, and 2 and 4 wk of age respectively with a formalin killed aluminum hydroxide adsorbed bacterin prepared from three strains of Haemophilus parasuis isolated from Ontario pigs affected with Glasser's disease. When challenged two weeks later with the homologous strains of virulent bacteria, all the vaccinated pigs remained healthy, while 17/18 nonvaccinated pigs became severely sick or died between three and seven days postchallenge. The one surviving nonimmunized pig was retarded in growth. All of the nonimmunized pigs had visible lesions of polyserositis, the most common being polyarthritis (14/18). Other lesions were ribrinous meningitis, pericarditis, pleurisy and/or peritonitis. Two of the pigs died with a septicemia. Haemophilus parasuis was isolated from 15/18 nonimmunized pigs, usually from several of the affected sites. The organisms were not isolated from the immunized pigs, nor from the surviving nonimmunized pig. Attempts to detect the presence of specific antibodies against the H. parasuis strains in the sera of the immunized or exposed pigs by the passive hemagglutination test or by enzyme linked immunoassay were unsuccessful. The results of this work indicate that primary SPF pigs can be protected from Glasser's disease by vaccination as early as 2 and 4 wk of age. The nature of this protective mechanism was not established in this study.