Causes of enlarged sternal bursas (breast blisters).

Bursas were taken weekly as normal turkeys developed from 3 to 22 weeks of age, and no specific bacterial or viral infection was found. Bacterial cultures were also made of condemned bursas taken at processing. Of 144 collected, 91% were sterile; the others had staphylococci, streptococci, or coliform organisms. Experiments with turkeys measured the effect of strain, body conformation, completeness of breast-feather cover, protection of the keel with sheepskins, age when put on range, and type of range on the incidence of enlarged sternal bursas. The strain difference of 25.4% breast blisters against 11.5% was highly significant (99% confidence). In one experiment the effect of feather cover was significant at the 95% level of confidence (61.7% breast blisters with no feather cover, versus 40% with complete feather cover). The effect of protecting the breast with sheepskin was significant at the 95% level of confidence in reducing incidence of breast blisters. There was no significant difference in the incidence of breast blisters in relation to body conformation, age, or type of range.

The structure of the sternal bursa of turkeys.

The sternal bursa developed as a microscopically recognizable synovial sac in turkeys at about 4 1/2 to 6 weeks of age. In birds 12 weeks old it was difficult to delineate the bursa grossly although microscopically it was a definite structure. After 12 weeks, the walls of the bursa were thick enough that the limits of the sac could be determined grossly. The synovial membrane was in the subcutis, and microscopically was a vascular band of loose to dense connective tissue of variable thickness. Laterally the membrane was folded so that in cross section it appeared as a tonguelike projection of variable length into the cavity. The lining cells centrally were flat fibroblasts while laterally they were cuboidal, particularly over the lateral folds. In older turkeys the cuboidal lining cells were sometimes stratified.

Tissue changes in enlarged sternal bursas of turkeys.

Enlarged sternal bursas evident in turkeys beyond 12 weeks of age were examined grossly and microscopically in 169 turkeys 3 to 26 weeks old. Grossly, the enlarged sternal bursas were sacs of varied size and wall thickness containing fluid in amounts from a fraction of a milliliter up to 70 ml. The fluid was usually the consistency of serum but was sometimes viscid, and in infected bursas it would be purulent. Its color varied from amber to red to dark brown depending on the amounts of and the changes in the blood pigments. The synovial membranes were smooth and glistening and of variable thicknesses. Strands or cords of the synovial membrane of variable thickness and number extended from side to side of the sac. Microscopically, the synovial membrane was focally thickened in the small bursas and generally thickened in the larger bursas. The thickening was the result of an increase in the very cellular fibrous tissue and in the number and size of blood vessels. The lining cells were flat fibrocytes one cell thick in the smaller bursas, and round stratified cells in the larger bursas. In infected bursas, mononuclear and heterophilic infiltration occurred. Hemorrhaging occurred quite often, the result of trauma to the highly vascular synovial membrane.

Decoquinate in the control of experimentally induced coccidiosis of calves.

Decoquinate administered orally in a grain mix at dosages of 0.5, 0.538, 0.7, and 0.8 mg/kg of body weight suppressed oocyst discharge and bloody diarrhea in calves inoculated 3 days later with 100,000 oocysts of Eimeria bovis (experiment 1, n = 12 calves) or with 100,000 oocysts each of E bovis and Eimeria zuernii (experiment 2, n = 16 calves). Doses of 0.1, 0.163, 0.243, 0.3, and 0.362 mg/kg of body weight gave only partial suppression of oocyst discharge and diarrhea. Clinical signs of coccidiosis did not recur for 23 days after the treatment was discontinued.