Certain authors declare that the thorax is depressed between the front limbs, but this symptom is of no particular value, and is also common to osseous cachexia and rachitis. Paralysis of the tongue and of the lower jaw is of greater importance. In exceptional cases, where the cysticerci are very numerous and penetrate the brain, signs of encephalitis, vertigo, and turning sickness (gid, sturdy) may be produced. These signs, however, disappear, and the cysticerci undergo atrophy. Interference with movement may give rise to suspicion when the toes of the fore and hind limbs are dragged along the ground, and thus become worn. This peculiarity is due to the presence of cysts in the muscles of the limbs, but it occurs in an almost identical form in osseous cachexia.
Fig. 33.—Large (a) and small (b) hooks of pork-measle tapeworm (Tænia solium). × 280. (After Leuckart.)
One symptom alone is pathognomonic, and it appears only at a very late stage—viz., the presence of cysts under the thin mucous membranes which are accessible to examination, such as those of the tongue and eye.
Fig. 34.—Mature sexual segments of pork-measle tapeworm (Tænia solium), showing the divided ovary on the pore side. cp, Cirrus pouch; gp, genital pore; n, nerve; ov, ovary; t, testicles; tc, transverse canal; ut, uterus; v, vagina; vc, ventral canal; vd, vas deferens; vg, vitellogene gland. × 10. (After Leuckart.)
Visual examination then reveals beneath these mucous membranes the presence of little greyish-white, semi-transparent grains the size of a grain of barley, or even larger. Unfortunately, in an animal so difficult to handle as the pig, this visual examination is decidedly troublesome, and is usually replaced by palpation. In many instances the disease does not attract attention during the patient’s life, and is only discovered on slaughter in consequence of the lesions by which it is characterised.
Diagnosis. As the characteristic lesions of cysticercus disease are to be found in the depths of the muscular and connective tissues, and as the external symptoms may be regarded as of doubtful significance, the diagnosis can only be confirmed during life by manual examination of the tongue. This examination of the tongue has been practised since the earliest times. Aristophanes even speaks of it, and in the Middle Ages it was performed under sworn guarantees. The regulations concerning the inspection of meat have finally led to the suppression of this calling.
In this method of examining the tongue, the operator commences by throwing the animal on its side, usually on the right side, and holding it in this position by placing his left knee on its neck. He then passes a thick stick between the jaws and behind the tusks, opens the mouth obliquely, raising the upper jaw by manipulating the stick. Finally he fixes one end of this last by placing his foot upon it, and holds the other extremity by slipping it under his left arm. In this position he is able to grasp the free end of the tongue and by digital palpation to examine the tongue itself, the gums, the free portions of the frænum linguæ, etc.
