Dose response relationship of Haemophilus pleuropneumoniae aerosols in pigs.

The virulence of Haemophilus pleuropneumoniae was quantitated for ten and 12 week old pigs following aerosol exposure. The volume and concentration of culture aerosolized, the estimated numbers of organisms inhaled by the pigs and the mortality rates at 72 hours postexposure were computed and used to calculate the LD50. There was correlation between the concentration of culture aerosolized, the amount of the estimated inhaled dose and the mortality rates. The ten week old pigs were apparently more susceptible to aerosols of H. pleuropneumoniae than the 12 week old pigs. The LD50 value or a multiple of it appears to be a reasonable basis for a standardized aerosol challenge of the immunity of pigs vaccinated with experimental or commercial H. pleuropneumoniae vaccines.     

Studies on the pathogenesis of staphylococcal osteomyelitis in chickens. I. Effect of stress on experimentally induced osteomyelitis

A single strain of Staphylococcus aureus was used to study the pathogenesis of osteomyelitis in chickens. The disease was consistently reproduced in 6-week-old broiler chickens when 1 X 10(5) or more organisms were given intravenously. Severe feed restriction, debeaking, and single or multiple injections of corticosteroids delayed the appearance and decreased the severity of lesions due to staphylococcal infection. This increased resistance was associated with increased numbers of circulating heterophils and monocytes. No correlation between the presence of tibial dyschondroplasia and osteomyelitis was found.     

Pig production in the Solomon Islands

In the Solomon Islands pigs grow slowly and sows have small litters. An experiment using 124 pigs in 16 litters from eight sows compared the effect of village breed, village diet and village husbandry which encouraged infection of pigs with Stephanurus dentatus, with the effect of European breed, commercial rations and a system of management which ensured freedom from S. dentatus infection on the productivity of pigs. It was shown that the village diet was markedly inferior to the commercial rations and had by far the greatest influence of any of the three factors studied on the parameters measured. The village breed was not inferior in litter size or growth rate when fed on the village diet, but was inferior in growth on the commercial diet. No harmful effects of the village husbandry system were detected on either type of pig but this may have been due to the lightness of S. dentatus infections.     

Water deprivation test in the dog: maximal normal values.

Studies were undertaken to determine maximal urine osmolality and urine specific gravity following water deprivation for 20 dogs with normal renal function. In addition, the reliability of body weight, skin pliability, total plasma protein concentration, and packed cell volume as indices of negative water balance was assessed. Following water deprivation for periods sufficient to induce dehydration, the mean maximal urine osmolality was 2,289 mOsm/kg. The corresponding mean maximal urine specific gravity was 1.062 and ranged from 1.050 to 1.076. The ratio of mean maximal urine osmolality to mean serum osmolality at the time of peak urine concentration was 7.3. There was no detectable difference in urine concentration indices between males and females. Changes in skin pliability and packed cell volume proved unreliable as estimates of dehydration. Weight loss and increases in total plasma protein concentration proved to be more consistent indicators of hydration status. Abnormal increases in serum urea nitrogen and serum creatinine concentrations occurred rarely, even though some dogs had water withheld for periods of up to 96 hours.     

Use of a silicone membrane feeding technique in the laboratory maintenance of a colony ofOrnithodoros moubata

Summary AdultOrnithodoros moubata from a laboratory colony were fed on mice or through natural or artificial membranes on pig blood. The rate of feeding and its efficiency as assessed by fecundity were markedly superior when membranes rather than live mice were used. Artificial silicone membranes offer major advantages of both convenience and economy over alternative membranes in the maintenance of soft tick colonies.

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Resumen Se alimentaron garrapatas adultasOrnithodoros moubata en una colonia de laboratorio, en ratones y a través de una membrana artificial con sangre porcina. La rata de alimentación y la eficiencia de la misma, evaluada mediante fecundidad de los ácaros, fue superior cuando se alimentaron a través de la membrana artificial. Las membranas de silicona, ofrecen mayores venajas operacionales y económicas, sobre otras alternativas, para alimentar garrapatas blandas en colonias.

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Résumé DesOrnithodoros moubata adultes d'une colonie de laboratoire ont été nourris sur des souris-h?tes ou à travers des membranes naturelles ou artificielles sur du sang de porc. Le taux de gorgement et son efficacité tel qu'évalués par le taux de fécondité est significativement supérieur quand on utilise des membranes plut?t que des souris vivantes. Les membranes artificielles de silicone présentent des avantages majeurs à la fois de commodité et d'économie par rapport aux autres sortes de membranes pour l'élevage des colonies de tiques molles.

     

Comparison of common antibiotic therapies for haemophilus pleuropneumonia in pigs

Three experiments were done to evaluate some antibiotic therapies that are used commonly to treat pigs infected with Haemophilus pleuropneumoniae. Haemophilus-free piglets, 12 weeks of age, were challenged in a chamber with an aerosol of H. pleuropneumoniae serotype 1 and were medicated with antibiotics at various times before or after challenge. Antibiotic formulations which are commonly used to treat pneumonia in swine were used. They were chloramphenicol, penicillin, and a long-acting formulation of oxytetracycline given intramuscularly; and oxytetracycline, chloramphenicol and spiromycin (investigated as a potentially useful antibiotic) given in solution as the sole source of drinking water. Infection, disease (death, fever, gross lung lesions) and growth rate were measured in pigs following experimental challenge.