Symptoms. Peritoneal cysticercosis is often of so mild a character, and the number of embryos which penetrate the body so small, that in the majority of cases there are no visible symptoms. It is not until the meat comes to be dressed by the butcher that little cysts (Cysticercus tenuicollis) are discovered in the abdominal cavity.
Unfortunately, in exceptional cases it may also happen that the number of embryos in the abdominal cavity is so great as to produce lesions of acute hepatitis, acute peritonitis, and sometimes pleurisy. These grave forms are more common in young pigs and lambs.
The animals appear dull, feeble, exhausted and without appetite, but exhibit marked thirst, lose flesh and become anæmic in a few days. Soon afterwards they show symptoms of acute peritonitis, with exudation of fluid, and death may follow in a week or two.
In cases where infestation is less marked, the animals may exhibit only progressive anæmia, without well-developed symptoms of peritonitis, until death occurs.
Lesions. On post-mortem examination a sero-sanguinolent exudation is seen, together with more or less numerous false membranes, and a varying number of young cysticerci floating freely in the liquid or enclosed in the folds of the mesentery. The cystic vesicles are spherical, ovoid, or elongated, and translucid or opalescent. They are some millimètres in diameter, and in some cases are very numerous, ranging from a few hundreds up to several thousands, but in others comparatively few.
The liver shows signs of intense hepatitis, caused by embryos burrowing into its tissue.
Causation. The causes are limited to a single fact, viz., ingestion of the eggs of Tænia marginata, which are spread over the fields in the excrement of dogs suffering from that parasite.
Diagnosis. The diagnosis can only be arrived at by a post-mortem examination, when cysticerci in various stages of development are discovered.
Prognosis. The prognosis is difficult to indicate, because everything depends on the intensity of the infestation.
Treatment. No curative treatment is possible, direct action on the developing parasites being impracticable. Nevertheless, some patients survive, and after having shown grave general disturbance may gradually improve.