Causation. The various forms of intestinal helminthiasis are all due to embryos or eggs of worms obtaining entrance to the stomach or bowels of susceptible animals. Nevertheless, external conditions largely favour infestation. The existence of marshes, ponds, and stagnant water on certain pastures, heavy annual rainfall, the occurrence of wet seasons, etc., favour the existence and growth of embryos, and, as a consequence, the infestation of animals.
Fig. 118.—Adult specimen of the fringed tapeworm (Thysanosoma actinioides). (After Stiles, 1893.)
The symptoms of intestinal helminthiasis are always very vague, whether the victims be oxen, sheep, or goats. They point to the slow and progressive development of a pernicious anæmia, characterised primarily by interference with appetite and digestion, then by anæmia, and finally by cachexia. The patients are dull, lose condition, suffer from depraved appetite, and, during the cachectic period, from diarrhœa, and die in a condition of exhaustion. These forms of helminthiasis are much more frequent in sheep than in oxen.
The diagnosis is only arrived at by discovering parasites in the fæces, or, in those doubtful cases where one has been led to make a microscopic examination of the excrement, by the detection of large numbers of eggs.
From an economic standpoint the prognosis is grave, because severely infected animals recover their condition very slowly, whatever treatment be adopted.
Treatment includes the measures previously indicated regarding the destruction of germs, eggs, or embryos distributed over the pastures, and the drainage of wet grounds and stagnant pools. Where such diseases are common, the pastures should be dressed with iron sulphate, and the stable manure disinfected or burned.
Curative treatment comprises the administration of such anthelmintics as can be given with the food. They should not require to be administered by force, as this proceeding would not only necessitate a great loss of time, but might result in accidents.
Arsenious acid, in doses of 15 grains per day, and tartar emetic, in doses of 75 to 150 grains, according to the animal’s size, are among the best drugs for oxen, and may be given for four or five days running. Benzine, oil of turpentine, and empyreumatic oil are more difficult to administer.
In the case of sheep, preference should be given to areca nut, in doses of 75 to 120 grains, according to the animal’s size, and to tansy, which are convenient to give, and can be added to bran, oats, or beetroot.