A contribution to the study of the pathology of oesophagostomiasis in sheep

Abstract

(1) Although toxins for the experimental reproduction of the disease have not actually been obtained from the nodular worms, there is very strong circumstantial evidence that during the course of the disease poisonous substances are formed and that these can produce the symptoms, lesions and death in the absence of bacterial and other complications. (2) Although insufficient cases were available for haematological study, there seems to be a possibility that the toxic action of the parasites may also produce a certain amount of atrophy of the haemopoietic tissues leading to oligocythaemia, but a deficiency of the red cells to the extent of a clinical anaemia was not observed. In some cases there is an eosinophilia. Whether this is due to their increased production in the myeloid tissues and their subsequent mobilization, or, whether they are produced locally in the walls of the intestine and are released temporarily into the circulation at the conclusion of the active tissue verminosis, cannot be stated with certainty. (3) In some cases bacterial complications producing various forms of superficial and/or deep enteritis, as well as peritonitis, are contributory factors in the causation of symptoms and mortality in the disease. (4) In some of the lesions there is a definite anatomical basis for the development of partial stenosis and intussusception. Apart from such accidents, the nodules themselves, even though they may be responsible for very extensive tissue destruction, do not seem to produce nutritive or other disturbances, in the absence of parasites in the lumen of the intestine and in the absence of bacterial complications.