Veterinary Surgeon Schmidt kept these animals under observation, and reinoculated them from time to time with highly virulent material, notwithstanding which they were still perfectly well six years after the first inoculation.
In practising this method, however, the trypanosomata used for the first inoculation must not be unduly weakened. The method would have appeared fully successful were it not for the fact that the protected and apparently quite vigorous animals still suffered from the presence of parasites in the blood. To extend its use, therefore, meant that one would not suppress, but would spread the disease. The effect would be to produce herds harbouring the parasite, which herds, though exhibiting no signs of illness, would nevertheless in a sense be propagating the active cause. Further observation has also shown that the protection so conferred is only relative. Dogs can always be infected with the blood of such animals. It has long been known in Africa that antelopes and buffaloes harbour trypanosomata in their blood without showing external signs of disease.
Another method of protection must therefore be sought, such as destroying the various stinging flies; but this offers little hope of success. Koch admits that he sees no method of dealing with them. The other method is directed against the parasite, and here he seems more hopeful. The disease can be rooted out by killing all diseased animals suspected of disease. The line of procedure is indicated by the experience gained in Mauritius and Java. When surra broke out in Mauritius almost all the oxen died in two years. In Java the nature of the disease was early recognised, and all suspected animals were at once slaughtered or isolated until slaughtered; in this way the disease was soon stamped out.
LOUPING-ILL.
The close analogy between the convulsive form of the disease described as “trembling” (which disease is well known in France) and the condition known in Britain as louping-ill lead us to give here a short account of the latter condition. For a great part of what follows we are indebted to articles by Meek and Greig Smith, published in the Veterinarian, Vol. LXIX, Nos. 820 and 840.
Nature and Symptoms of the disease. The disease known usually as louping-ill or trembling has long been of annual and sometimes of biennial recurrence in certain parts of Great Britain. In these places sheep farmers look for the appearance about the middle of April, to its continuation during May, and to its gradual disappearance early in June. Lambs are most liable, but sheep are also quite susceptible to the disease, and in both the symptoms are the same. The disease under consideration is rendered quite distinct by certain well-known symptoms. Though these have been described in various ways, the disease can be recognised by the more or less complete paralysis of the body and limbs. Symptoms may succeed one another very rapidly, or may be spread over some length of time. The animal at first loses control over the muscles, which are seen to twitch convulsively. It may fall down and struggle on the ground, sometimes jumping up again, often to some height. Between the fits it is often seen to stand trembling. These symptoms are frequently accompanied by frothing at the mouth. Some such appearances are the usual onset to the disease, and are followed by a paralysis which usually affects the hind limbs, but may also include more or less of the body and the head and neck. The fore limbs are often similarly paralysed. The affected limb or limbs become cold to the touch. The paralysis necessarily brings the animal to the ground, though it may be able to crawl about by the aid of the unaffected legs. When the head and neck are affected the former is usually drawn to one side, and the eyes often become oblique. Excitement is greatly increased when the animal is disturbed. The symptoms, then, in a few words are more or less complete paralysis, preceded as a rule by fits and trembling.
The small number which recover present “a wry neck, stiff joint, high back, or other deformity.” During recovery swellings occur at the joints; these may be pierced with good results, giving a large discharge of pus. According to Fair, in the Veterinarian, Vol. VIII., “these abscesses usually appear in the neighbourhood of the joints, but sometimes above the arms, the brisket, or any neighbouring part of the body.”
While the disease is characteristically a sheep ailment, other animals are also liable. Swine fed with the carcases or blood of sheep which have succumbed to louping-ill die with every characteristic of the disease in a short time. If the carcase has been boiled this does not occur. Swine will also frequently take the malady if allowed access to the grass of affected fields. Cattle are said to take the disease, and in the North Tyne district it is said that if a cow takes louping-ill, the milk will give the illness to a calf or lamb. One or two cases of horses being attacked are also reported.
Regarding the infectious character of louping-ill, the following is very well known. Sheep bred on diseased places are not nearly so liable to the disease as sheep which have been introduced from unaffected places. Louping-ill may be introduced into a new place, but in such cases, unless the importation from affected farms be continued, the malady may disappear.
Distribution of the disease. In Great Britain it is confined to the North Tyne district of Northumberland and to the contiguous border counties of Scotland, extending into Kirkcudbrightshire and certain valleys of Dumfriesshire. It is rare in Berwickshire, common in the north and west of Roxburghshire and the similar hilly districts of Selkirkshire and Peeblesshire. It occurs in Ayrshire, to a slight extent in Lanarkshire, and is found in the western parts and islands of Argyleshire and Inverness-shire.