Causation. The exact cause of this form of dysentery in new-born calves has not yet been identified, but the disease is undoubtedly a microbic enteritis, and may even be a primary septicæmia of puerperal origin.
For a very long time this dysentery was mistaken for simple diarrhœa, though it exhibits neither the characteristics, course, nor termination of the latter disease.
The co-existence of epizootic abortion and dysentery in certain byres has led some authors to believe that a connection exists between the two diseases, and that the young are infected with dysentery at birth. Evidently, intra-uterine infection is not exceptional, and it seems quite natural that the new-born calf may equally suffer when the fœtal envelopes and fluids are infected before parturition. Epizootic abortion is probably not the only disease which may produce this condition.
The diagnosis is very simple. The course of the disease and its rapid development prevent it from being mistaken for ordinary diarrhœa. It is more difficult to distinguish from septicæmia of umbilical origin, although this disease also has well-marked characteristics.
The prognosis is not hopeful. Statistics show that almost all the affected animals die, and that those exceptional cases which survive remain puny and sickly. There is no economic advantage in attempting to save them.
The mothers of affected calves seldom show any sign of illness, though the after-birth is often retained.
Lesions. The macroscopic lesions are of very trifling importance compared with the gravity of the disease. The digestive tract appears congested throughout. The intestinal mucous membrane is moderately swollen, but without gross lesions. The intestinal contents exhale a sickly, fœtid odour. The smaller vessels and capillaries forming the peripheral vascular network appear distended, as in septicæmia. The carcases putrefy with extreme rapidity.
Curative treatment is very uncertain. Varying results have been obtained with doses of 4 to 5 drams of slight purgatives like borotartrate of potassium, sodium sulphate, and magnesium sulphate; small doses of intestinal antiseptics like salicylic acid, 15–grain doses of salicylate of soda, 45 to 75 grains of carbolic acid, 2 per cent. carbolic solution in doses of 7 to 12 drams; 1 per cent. Lysol solution in doses of 2 to 4 ounces; benzo-naphthol, lactic acid 45 to 75 grains, tar water, lime water, etc. Although all these preparations, when carefully used, generally give good results in the early stages of simple diarrhœa, they appear to fail in dysentery of new-born calves.
Prophylactic measures are more reliable. They consist:
(1.) In scrupulous disinfection of the byres when the first case of abortion occurs;