Resistance of Pasteurella multocida A:3,4 to phagocytosis by turkey macrophages and heterophils

A virulent field isolate and 2 vaccine strains of Pasteurella multocida A:3,4 were compared for resistance to phagocytosis by turkey macrophages and heterophils, using in vitro assays. The least virulent vaccine strain (M-9) was phagocytosed to a greater degree than was the field isolate or the other vaccine strain (Clemson University). All 3 bacteria differed significantly from each other in the amount of capsular material present as measured by polycationic ferritin labeling and electron microscopy. Removal of the capsule with hyaluronidase resulted in a significant increase in phagocytosis of the field isolate.     

The use of the log-linear model to evaluate the effects of three herd factors on Streptococcus agalactiae mastitis occurrence in California, 1977

Epidemiologic relationships among Streptococcus agalactiae infected dairy herds and herd size, location and California Dairy Herd Improvement Association (CDHIA) participation were examined using log-linear methodology. Dairies located in five out of the six California Bureau of Animal Health veterinary districts were studied. Data sources included the Dairy Cattle Data Base, which uniquely identifies each of the 2875 dairies in California, the 1977 statewide CDHIA year-end summary report and microbiological results from a 1977 statewide survey of bulk tank milk samples. These data were merged, fitted and the best model selected using likelihood-ratio statistics. The model included all four “main effects”, the six possible “1st-order effetss” and the “2nd-order effect” due to the interaction of herd size, location and CDHIA participation. Subsequently, a logit model was used to estimate the effect of the independent herd factor variables (size, location and CDHIA participation) on the log odds of the dependent S. agalactiae variable. This model required conditioning on the three-way relationship among the independent variables.medium-sized, non-CDHIA herds in district 2 (northcentral California) showed the highest expected odds (3.37) for S. agalactiae in bulk tank milk, while small, CDHIA herds in district 3 (northcentral coastal California) produced the lowest odds (0.39).     

Production and characterization of monoclonal antibodies to psittacine beak and feather disease virus.

Monoclonal antibodies specific for the virus that causes psittacine beak and feather disease (PBFD) were produced by fusing spleen cells from mice immunized with purified concentrated PBFD virus with mouse myeloma cell line Sp2/0. The resulting hybridomas were tested for reactivity against whole purified virus by an enzyme-linked immunosorbent assay (ELISA) system. Four clones, designated 15H8, 8E3, 11G12, and 2C3, were subcloned by limiting dilution. Isotyping indicated that clone 15H8 was secreting IgG, whereas the remaining clones secreted IgM. The secreted immunoglobulins were characterized by reactivity against purified PBFD virus using immunoblotting procedures, by immunohistochemical staining of virus-induced lesions in infected tissues, and by inhibition of PBFD virus agglutination of cockatoo erythrocytes. Antibodies secreted by clones 15H8 and 8E3 had the strongest activity against purified whole virus. Only immunoglobulin secreted by the clone 15H8 could be used to detect viral antigen in infected tissues. None of the monoclonal antibodies had hemagglutination-inhibition activity.     

Reducing the proportion of animal protein in feed for rainbow trout (Salmo gairdneri). 2. Supplementation of methionine and lysine

Continuing previous investigations, two test feedstuffs whose fishmeal content had been reduced to 5% and which were supplemented with 4.5 g methionine and 5.0 g lysine per kg resp. 6 g methionine and 6 g lysine per kg were proofed in comparison with a fattening feed for trout as customary in trade and with a fish meal content of 35%. The content of animal protein in the control feed was at least 75% (crude protein content 41%), in test feed I at most 35% (crude protein content 35.4%), in test feed II at most 17% (crude protein content 33.9%). All feedstuffs had the same energy content. The tests were made with rainbow trout (Salmo gairdneri) of 80...100 g at the beginning and at water temperatures of 11...12 degrees C. They were conducted over a period of 112 days. After giving the same amount of feed, growth of and feed expenditure for the fish feed with the test feedstuffs were less suitable than of those fish which had received the control feed. Concerning the protein efficiency ratio, the productive protein value and the energetic expenditure too, the best results were achieved with the control feed.     

Variations in muscle fiber composition between successfully and unsuccessfully raced quarter horses

Muscle biopsy samples were removed from the m gluteus medius of 47 retired running Quarter Horse (QH) mares. Horses were separated based on bloodline, past racing history and percentage Thoroughbred (TB). The bred to run and raced (BRRA) and bred to run and not raced (BRNR) groups possessed a lower percentage (P<.01) of fast-twitch low oxidative (FT) fibers (BRRA 38.6 and BRNR 36.2±2.54 respectively). These horses also possessed a higher percentage (P<.01) of fast-twitch high oxidative (FTH) fibers (BRRA 52.5 and BRNR 48.5±2.54, respectively) than not bred to run and not raced (NBNR) horses. Horses that were bred to run had higher (P<.05) FTH to FT fiber ratios (1.44) than horses that were not bred to run (.94). Successful racehorses possessed a lower percentage (P<.05) of slow-twitch (ST) fibers and a higher percentage (P<.05) of FT fibers than unsuccessful racehorses. Success or failure was determined by Speed Index. No differences (P>.05) were found in the percentage FTH fibers between successful and unsuccessful horses.     

Ultrastructure of the gastrocnemius tendon and sheath from broilers infected with reovirus

Gastrocnemius tendon and sheath from male broilers infected with reovirus at 1 day of age were evaluated ultrastructurally at 1, 2, 3, 4, 5, 10, 15, and 20 weeks postinoculation (PI). Although virus particles were not identified, degenerative changes in sheath and tendon fibroblasts were characterized by cytoplasmic vacuolization, disruption of membranes, and loss of ribosomes from rough endoplasmic reticulum, mitochondrial degeneration, and cell disruption.     

Efficacy of tulathromycin in the treatment and prevention of natural outbreaks of bovine respiratory disease in European cattle

The efficacy of tulathromycin in the treatment (phase 1) and prevention (phase 2) of bovine respiratory disease (BRD) was evaluated on commercial farms in France, Germany, Italy, and Spain. In phase 1, commingled cattle with clinical BRD were treated with tulathromycin (n = 128) or florfenicol (n = 125) on day 0. Similar percentages of animals showed sustained clinical improvement at day 14 (tulathromycin 83.3% versus florfenicol 81.0%) and had not relapsed by day 60 (tulathromycin 63.3% versus florfenicol 58.4%). In phase 2, healthy in-contact cattle were treated with tulathromycin (n = 492), tilmicosin (n = 494), or saline (n = 265) on day 0. Significantly more (P = .0001) tulathromycin-treated cattle remained healthy to day 14 (92.4%) than tilmicosin-treated (83.7%) or saline-treated (63.7%) cattle, and this was maintained through day 60 (tulathromycin 85.4% versus tilmicosin 75.1% and saline 56.2%). Tulathromycin was highly effective in the treatment and prevention of BRD.     

Evaluation of tulathromycin for the treatment of pneumonia following experimental infection of swine with Mycoplasma hyopneumoniae

Tulathromycin was evaluated in the treatment of pneumonia in weaned pigs inoculated intranasally with Mycoplasma hyopneumoniae. Five days postchallenge, the pigs were randomized to treatment with a single IM administration of saline, a single IM administration of tulathromycin (2.5 mg/kg; day 0), or three IM administrations of enrofloxacin (5.0 mg/kg; days 0, 1, 2). Pigs were necropsied on day 12 or 13. Unchallenged controls remained healthy with no lung pathology. Compared with saline, coughing, mean lung lesion score, and proportional lung weight were significantly reduced and weight gain was significantly greater for tulathromycin-treated pigs (P < .05). Compared with enrofloxacin, there were no significant differences in proportional lung weight or weight gains, but coughing and lung lesion scores were greater for tulathromycin-treated pigs (P < .05). Tulathromycin was effective in the treatment of pneumonia following experimental infection with M. hyopneumoniae.     

Evaluation of cardiac lesions and risk factors associated with myocarditis and dilated cardiomyopathy in southern sea otters (Enhydra lutris nereis)

OBJECTIVE: To describe cardiac lesions and identify risk factors associated with myocarditis and dilated cardiomyopathy (DCM) in beach-cast southern sea otters. ANIMALS: Free-ranging southern sea otters. PROCEDURE: Sea otters were necropsied at the Marine Wildlife Veterinary Care and Research Center from 1998 through 2001. Microscopic and gross necropsy findings were used to classify sea otters as myocarditis or DCM case otters or control otters. Univariate, multivariate, and spatial analytical techniques were used to evaluate associations among myocarditis; DCM; common sea otter pathogens; and potential infectious, toxic, and nutritional causes. RESULTS: Clusters of sea otters with myocarditis and DCM were identified in the southern aspect of the sea otter range from May to November 2000. Risk factors for myocarditis included age, good body condition, and exposure to domoic acid and Sarcocystis neurona. Myocarditis associated with domoic acid occurred predominantly in the southern part of the range, whereas myocarditis associated with S. neurona occurred in the northern part of the range. Age and suspected previous exposure to domoic acid were identified as major risk factors for DCM. A sample of otters with DCM had significantly lower concentrations of myocardial L-carnitine than control and myocarditis case otters. CONCLUSIONS AND CLINICAL RELEVANCE: Cardiac disease is an important cause of death in southern sea otters. Domoic acid toxicosis and infection with S. neurona are likely to be 2 important causes of myocarditis in sea otters. Domoic acid-induced myocarditis appears to progress to DCM, and depletion of myocardial L-carnitine may play a key role in this pathogenesis.