In the United States of America a worm is frequently found in the fat surrounding the kidneys of pigs, and is supposed by farmers to be the cause of paralysis of the hind limbs.
This so-called kidney worm of hogs (Sclerostoma pinguicola) should not be confounded with the kidney worm (Dioctophyme viscerale) of dogs and man. Both of these parasites belong to the same zoological family (Strongylidæ), but to different subfamilies and genera. The kidney worm of dogs grows to a length of 1 to 3 feet. The kidney worm of hogs is much smaller, attaining at most something less than 2 inches in length.
Fig. 233.—Embryos of Sclerostoma pinguicola. (Louise Taylor, Annual Report, U.S.A. Bureau of Animal Industry, 1899, p. 634.)
The body of the worm is plump, mottled in color—red, yellow, white, black—according to the organs visible beneath. The average female is about 37 mm. and the average male 32 mm. in length. The worms seem to occur in pairs, usually in cysts or canals; thus, upon the examination of two kidneys with their surrounding fat, fifteen specimens were found, seven males and eight females. The connective tissue layers between the fat were found to be the most general seat of infection, and the cysts were numerous and closely packed together. Although a cyst usually contained two worms, a male and a female, sometimes three were found together, two females and one male, or just as often one female and two males. The cysts contained pus, which bathed the parasites, and in which were thousands of eggs in the segmentation stage. Still, other cysts, upon being cut into, were found without parasites and in a necrotic condition.
It will be noticed that Sclerostoma pinguicola is colloquially known as the kidney worm. In no case, however, has Miss Taylor found it in the kidney substance, but only in the tissue surrounding this organ; the lard appears to be its normal habitat, at least.
Just how the eggs leave the kidney fat or enter the bodies of fresh hogs has not been demonstrated, but it does not seem unreasonable to suppose that they eventually find their way out with the urine. Indeed, Dean reports eggs found in the urine. From analogy one is led to believe that no intermediate host is required, but that in all probability the embryos develop for a short time in water, casting several skins, and they eventually gain access to the hogs either through contaminated drinking water or food.
Because of the hog’s habits, it is difficult to see any practical measures which can be adopted to prevent infection. Feeding from troughs and supplying plenty of pure drinking water will decrease but not exclude the disease. Leuckart’s advice to the Germans, “Swine should be kept in a less swine-like manner,” holds good in all countries and in connection with all diseases. It is equally impossible to suggest practical methods of treatment. This is all the more true because it seems probable that a number of distinct complaints are popularly grouped together by the farmer as kidney-worm disease.
CHAPTER IV
GENITAL APPARATUS.
Semiology. The examination of the genital apparatus properly so called is easy in animals of large size, whether male or female, but is more delicate and difficult, and is sometimes partially impossible, in small creatures.