Death is very frequent at this stage of the disease; the animals eat little or nothing, refuse drink, and die of exhaustion.
All this general disturbance is of central origin, and is due to disseminated parasitic encephalitis, but up to this point the seat of the disease is not yet clearly apparent.
Second phase.—Turn-sick.—The central symptoms are slow of development, and are due to the progressive growth of one or two, more rarely three or four, fertile vesicles. These are the true symptoms of turn-sick, and it is only after this phase of the disease has developed that the term becomes appropriate.
Left at liberty, the patient usually walks in a circle towards the right or left in an impulsive and irresponsible fashion. Sometimes it describes a circle, always of the same size. In other cases, on the contrary, it travels along a spiral track, getting further from or nearer to the centre as the case may be. The turning movement may become so accentuated that the animal appears to revolve as on a pivot, and if it is confined in a field or straw-yard its legs become caught in the litter and it falls to the ground.
Attempts have been made under these circumstances to discover the exact point of compression, i.e., the point at which the cyst exists, by noting the direction of the turning movement. The diagnosis, however arrived at in this way is frequently illusory, because it is not uncommon to find two or three vesicles, and in any case the most important information in regard to diagnosis is to be derived from the ocular symptoms.
When only one vesicle exists, the turning movement usually occurs towards the side on which it is situated, and the eye of the opposite side is affected with amaurosis.
Fig. 219.—Sheep’s skull, the hind portion thin and perforated, due to the presence of gid bladderworms (Cœnurus cerebralis). (After Dewitz.)
If the cyst is situated near the olfactory lobes, the animal marches with a high-stepping movement and the head drawn back towards the body. If the cyst is in the cerebellum the animal is incapable of moving, because it can no longer co-ordinate its movements. Finally, if the cyst develops in the occipital region, animals turn towards the wind, with the neck raised and the head extended.
At the moment when they fall to the ground they sometimes have epileptiform convulsions, grind their teeth, and salivate profusely. In a severe attack even death may supervene at this point.