An Escherichia coli bacterial prostatitis was experimentally induced to determine the effect of bacterial infection on prostatic tissue zinc concentrations in castrated and gonadally intact male dogs. Five of the 22 mixed-breed dogs (group 1) had no culture evidence of infection 2 weeks after the instillation of bacteria into the prostate gland. The remaining 17 infected dogs were allotted to 2 groups; 1 group of dogs was subjected to castration (group CA, 7 dogs), and the other group of dogs was subjected to sham operation (group SO, 10 dogs). The groups were divided into groups of dogs with prostatic infection at necropsy (groups CA-I and SO-I), and those dogs without prostatic infection at necropsy (groups CA-N and SO-N). Urine, prostatic fluid, and prostatic tissue (week 0, 7, +/- 12) specimens were obtained for bacteriologic culturing to determine whether prostatic infection was present. Prostatic tissue was obtained at necropsy (week < 6, 7, or 12) for analysis of zinc concentration by atomic absorption spectrophotometry. The logarithmic mean prostatic tissue zinc concentrations were compared between groups. Group CA had a significantly lower prostatic zinc concentration than all other groups. Zinc concentrations were not statistically different between any of the other groups. Castration did decrease the prostatic tissue concentration of zinc, a known natural antibacterial factor. However, resistance to infection and resolution of infection were not correlated with prostatic tissue zinc concentrations in this experimental model.

Two recently developed direct methods, radioassay-125I-labeled hyaluronic acid binding protein (125I-HABP)- and high-performance liquid chromatography (HPLC), were used to assess and compare the concentration of hyaluronate (HA) in synovial fluid of horses. Also determined were changes in the HA concentration in an experimental treatment model involving physiologic saline solution (PSS)-irrigated or methylprednisolone acetate-injected tarsocrural joints of clinically normal horses. Serum HA concentration was determined simultaneously, using the 125I-HABP assay. Synovial fluid HA concentration values obtained by use of the HPLC method were approximately double the values obtained by use of 125I-HABP assay. Correlation (r = 0.819) between the 2 methods was highly significant (P < 0.001; linear regression analysis) for all samples studied and for various experimental subgroups. When pure HA standards were used, correlation between the 2 methods was close to 1 (r = 0.965; P < 0.001), with higher values obtained by use of the 125I-HABP assay. It is suggested that the HA binding protein derived from endogenous cartilage proteoglycan interferes with the 125I-HABP assay on synovial fluid, resulting in excessively low values, compared with those obtained using the HPLC procedure. Intra-articular injection of methylprednisolone acetate significantly (P < 0.01) increased synovial fluid HA concentration at 24 hours after injection. Increase was also detected after PSS irrigation, but owing to wide intersubject variation, this increase was not significant. The HPLC procedure, which provides simultaneous information about the concentration and degree of polymerization of HA, is recommended for the study of synovial fluid, whereas the 125I-HABP assay is more suitable for serum HA analysis.

Effects of the endophyte Acremonium coenophialum in tall fescue on pregnant mares and foal viability were evaluated. Twenty-two mature pregnant mares were randomly chosen to graze either Kentucky-31 tall fescue that was free from A coenophialum (endophyte-free, EF) or tall fescue infected with A coenophialum (endophyte-present, EP) after the first 90 days of pregnancy through parturition. Concentrations of pyrrolizidine and ergopeptine alkaloids were significantly greater in EP grass, compared with EF pasture. Ten of 11 mares grazing EP pasture had obvious dystocia. Mean duration of gestation was significantly greater for the EP group, compared with the EF group. Foal survivability was severely reduced among mares grazing Ep fescue with only 1 foal surviving the natal period. Udder development and lactation were low in mares grazing EP grass. The absence of clinical problems in mares grazing EF grass implicated the endophyte as the causative agent of reproductive problems and perinatal foal mortality in pregnant mares grazing endophyte-infected fescue grass. Caution should be exercised in allowing pregnant mares to graze pastures infected with the endophyte A coenophialum.

Estrogen receptors were measured in normal canine lymph nodes and neoplastic tissue from dogs with lymphoma, using a commercially available [3H]estradiol dextran-coated charcoal assay. Using the same assay, estrogen receptors were detected in the positive-control tissues--dog uterus, rat uterus, and lyophilized bovine uterus. Specific binding of [3H]estradiol was not detected in rat skeletal muscle or in any of the canine lymphoid tissues, indicating that the specimens did not contain estrogen receptors.

The effect of pulsed radio frequency therapy (PRFT) was evaluated on seven ponies with no arthritis and in 28 ponies in which arthritis was created using intra-articular amphotericin B to induce synovitis in the right middle carpal joint. The ponies were divided into five treatment and two control groups. Two levels of arthritis were created and two dosage levels of PRFT were evaluated. The effect of PRFT on arthritic and nonarthritic joints was measured by comparing synovial fluid parameters, the degree and duration of lameness, the range of carpal motion, and carpus circumference, for treated and untreated groups. Lesions seen radiographically at gross pathology, and by histopathology were also compared between the treated and control groups. In the ponies with a mild form of induced arthritis, PRFT significantly (p < 0.05) reduced the severity and duration of lameness, swelling of the carpus, and the severity of gross pathological and radiographic changes. In these ponies the synovial acid phosphatase levels were lower, the mucin clot quality was superior, and the synovial protein levels were lower for the ponies receiving PRFT as compared to the arthritic ponies receiving no treatment. A dose response effect was evident. In ponies with a slightly more severe form of arthritis, PRFT was evaluated at one dosage level. The treated ponies were significantly improved over the untreated ponies with respect to carpal range of motion, degree of lameness, carpus swelling, and radiographic lesions. No deleterious effects were noted when normal, PRFT treated, middle carpal joints were compared to contralateral untreated, normal joints. It was concluded that significant beneficial effects resulted when affected ponies were treated with PRFT.

In vitro adherence to intestinal epithelial cells by enterotoxigenic Escherichia coli strains bearing K88, K99, F41, or 987P adhesins and of their variants not bearing adhesins (K88-, K99-, or F41-) was investigated in European Large White and Chinese Meishan pigs. Possible relationship between adherence and virulence was also examined. The K88-positive (K88+) strain strongly adhered to intestinal epithelial cells from 26 of 28 Large White pigs. This strain had previously been found to be highly virulent for Large White pigs. The only surviving pig was of nonadherent phenotype, and cells from 4 dehydrated moribund pigs had strong adherence. By contrast, the same K88+ strain found previously to have little pathogenicity for Meishan pigs adhered with variable intensity to cells from 17 of 23 Meishan pigs; correlation was not evident between adherence and virulence. The K99+F41+ strain of porcine origin and the F41+ strain generally adhered strongly to cells from 24 and 23 Meishan pigs, respectively, and to cells from 25 of 26 Large White pigs. Correlation was not found between adherence and virulence for the 2 strains. A K99+F41+ strain of bovine origin adhered to cells from 20 of 22 Meishan and 22 of 23 Large White pigs, and a K99-F41+ variant adhered to cells from 19 of 23 Meishan and 23 of 24 Large White pigs. The adhesin-negative variants never adhered to intestinal epithelial cells. Strain 987 known not to readily produce 987P adhesin after in vitro growth never adhered to cells during the test. Results indicated that K88, K99, and F41 adhesins were responsible for in vitro adherence and, except for the K88+ strain in Large White pigs, adherent phenotype was not a sufficient condition to make a pig susceptible to enterotoxigenic E coli. The contribution of physiologic factors and their genetic origin to the degree of resistance of the individual is not yet completely understood for every enterotoxigenic E coli strain and breed of pig.

We determined that the protein profiles of 14 isolates from animals with hemorrhagic septicemia were relatively homogeneous and could be placed in 2 distinct groups on the basis of their country of origin. Such differences correlated with the serotypic properties of the individual isolates; hemorrhagic septicemia isolates of Asian and North American origin (Carter B) had a major protein band with an apparent molecular mass of 32 kDa, whereas those of African origins (Carter E) had a major protein band with an apparent molecular mass of 37 kDa. The possession of a major 32-kDa protein band appeared to be unique to Carter B isolates, suggesting that electrophoresis may be a useful nonserologic technique for the identification of organisms of this serotype. Other major bands with apparent molecular masses of 27, 45, and 47 kDa were shared by all strains, regardless of their serotype. The lipopolysaccharides were of low molecular mass and relatively uniform from 1 isolate to the next.

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.

Twenty-six mixed-breed (14 males, 12 females) dogswere used in a double-blind study to evaluate the effect of milbemycin oxime against naturally acquired infection with Ancylostoma caninum. Dogs were ranked and paired, on the basis of number of hookworm eggs/g of feces, and treatment was randomly assigned. Each dog was given either the study drug or placebo (1 tablet/11.4 kg [0.5 mg/kg] of body weight). Eggs per gram of feces enumeration was done on days 3 and 7 after treatment, and dogs were euthanatized on day 7. On day 3, 5 of the 13 dogs in the milbemycin-treated group had hookworm eggs in the feces (results of the McMaster test). In these dogs, mean number of eggs per gram of feces had decreased markedly (from 5,289 to 452) and, by day 7, was 114. At necropsy, 16 A caninum adults were recovered from 2 of the milbemycin-treated dogs. On day 3, 12 of the 13 dogs in the placebo-treated group had hookworm eggs in the feces. Mean number of eggs per gram of feces in these dogs decreased slightly (from 5,243 to 2,646), but did not decrease further by day 7. A mean number of 54.4 A caninum adults was recovered from 12 of the 13 placebo-treated dogs at necropsy. Milbemycin oxime had 97.8% efficacy against A caninum. Results also indicated that milbemycin oxime may be effective against Trichuris vulpis, but not against Dipylidium caninum.