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To determine whether Pasteurella multocida toxin (PMT) affects growth of the proximal portion of the humerus of young pigs.


20 colostrum-deprived, cesarean-derived pigs.

Design and Procedure

5 groups (n = 4/group) of pigs were formed. Group-1 pigs received 0.1 ml of phosphate-buffered saline solution for 4 weeks; group-2 pigs received 0.05 μg of PMT/kg of body weight at 14 and 21 days; group-3 pigs received 0.05 μg of PMT/kg at 28 and 35 days; group-4 pigs received 0.1 μg of PMT/kg at 14 and 21 days; and group-5 pigs received hyperimmune serum (from a sow given purified toxin) on days 13, 20, 27, and 34, and 0.1 μg of PMT/kg on days 14, 21, 28, and 35.


All pigs given 0.1 μg of PMT/kg without serum died or were euthanatized, as were 4 pigs given 0.05 μg of PMT/kg. These pigs had increased serum interleukin 1 and 6 bioactivities. Pigs surviving 0.05 μg of PMT had decreased weight gain, rough coat, marked atrophy of the ventral concha (as determined by turbinate perimeter ratios), and small stature. The surviving pigs also had reduced area and decreased proliferation indices in physeal chondrocytes on the basis of bromodeoxyuridine immunoreactivity. Control and serum-treated pigs gained weight, had no clinical effects, had similar physeal areas, and had higher cell proliferation indices.


PMT inhibits endochondral bone formation by reducing physeal area and chondrocyte proliferation in vivo. Hyperimmune serum neutralizes the effects of toxin on weight gain, clinical appearance, physeal area, and chondrocyte proliferation.

Clinical Relevance

PMT may affect growth of the skeletal system. Antiserum to PMT is protective. (Am J Vet Res 1996;57:848–852)

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in American Journal of Veterinary Research