Consumptive coagulopathy in turkeys exposed to Pasteurella multocida.

When turkeys were inoculated intramuscularly with live Pasteurella multocida, three of the four inoculated turkeys developed an increase in modified Russell's viper venom time (mRVVT) 24 hours after inoculation. This increase was followed by irregular decreases and increases in mRVVT at subsequent bleedings. When turkeys were inoculated intravenously with P. multocida, the mRVVT increased markedly after inoculation in all eight inoculated turkeys: 9 hours later, the average mRVVT was significantly (P < 0.05) higher than that of the uninoculated turkeys. No microthrombi were observed in the blood vessels of the liver, spleen, kidneys, or lungs. An increase in mRVVT was interpreted as an excessive consumption of one or more of clotting factors X, V, II, and I. These results indicate that consumptive coagulopathy could be a factor in the pathogenesis of fowl cholera in turkeys.

Histologic pattern of testicular regrowths in caponized tom turkeys.

Testicular regrowths were observed in 10 of 21 tom turkeys between 28 and 32 weeks old, which was between 19 and 23 weeks after surgical caponization at 9 weeks of age. Regrowths were not observed in younger caponized toms. Two types of histologic patterns that differed from the normal pattern were observed in these regrowths. The first pattern was observed in seven regrowths and was characterized by a higher density of seminiferous tubules and more interstitial cells. The second pattern was seen in three regrowths and was characterized by extensive intertubular fibrosis, tubular detachment, and an increased number of interstitial cells. No correlation was found between the presence of these regrowths and plasma testosterone levels. The interstitial cell hyperplasia in all regrowths possibly was related to a diminished negative feedback by the endogenous testosterone on the release of luteinizing hormone from the pituitary. The appearance of regrowths at this age probably was related to the onset of normal physiological puberty.

Comparative susceptibility of caponized and uncaponized tom turkeys to Pasteurella multocida.

When susceptibility to virulent Pasteurella multocida was compared, there was no significant (P greater than 0.05) difference between caponized and uncaponized tom turkeys. Neither was there any significant (P greater than 0.05) difference between the surviving caponized and uncaponized toms in the development of serum anti-P. multocida antibody. However, at 28 weeks of age, the average live body weight of the caponized toms was significantly (P less than 0.05) lower than that of the uncaponized toms. Turkeys were caponized when 9 weeks old, and different groups were exposed to P. multocida when 13, 18, 23, and 28 weeks old.

Comparison of live avirulent M-9, Minnesota, and CU fowl cholera vaccines.

The M-9 and Minnesota (MN) avirulent Pasteurella multocida vaccines were evaluated and compared with the Clemson University (CU) vaccine, which had been shown to be highly effective in preventing fowl cholera in turkeys. Neither the M-9 nor the MN vaccine given in the drinking water was as effective as the CU vaccine in protecting turkeys against challenge with virulent P. multocida. When grown in brain-heart infusion (BHI) agar as recommended, the M-9 was not as efficacious as when it was grown in BHI broth. The M-9 was as effective as the CU vaccine only when grown in BHI broth and given at 10 times the standard dosage. Injection of the M-9 vaccine into the air spaces of the head at a site near the caudal rim of the ear after one vaccination in the drinking water was not as effective for hyperimmunizing potential breeders as was the CU vaccine injected at the same site. A microtiter agglutination test demonstrated a significant (P less than 0.05) correlation between the level of anti-P. multocida antibody found 1 week after vaccination and survival after challenge with virulent P. multocida.