514 GrENERAL DISEASES. 



patient suffers from aggravated spasms from time to time, the 

 slightest noise or excitement being frequently sufficient to bring 

 them on. The bowels are constipated, and there is often retention 

 of urine, from the horse being unable to stretch himself out. In 

 very mild cases the animal may be aMe to lie down. As a rule, 

 the patient preserves his desire for food and drink ; but is unable to 

 gratify it, except to a very small extent, owing to the rigidity of 

 his chewing and swa.llowing muscles. 



" Recovery is rare before the third week. Generally about this 

 time, the muscular contraction begins to decrease ; the appetite im- 

 proves ; the breathing becomes calmer ; and the movements easier. 

 Very often the change for the better does not set in before the end 

 of the fifth or sixth week ; and the improvement continues through 

 a long period of uneasiness, rigidity of movement, and stiffness of 

 the spinal column [from the head to the tail]. Convalescence is 

 long, and is often protracted for several months" (Friedherger 

 and Frohner). 



IMMUNITY AND PROTECTIVE INOCULATION.— Horses may be 

 made immune from tetanus for a short time by one attack of this disease, or 

 by injecting, at first, extremely small doses of the tetanus poison, and 

 gradually increasing it to a very large amount, which can be done, later on, 

 without the animal becoming affected. This process of protective inoculation 

 could be carried out only under the direction of a capable bacteriologist. 



The immunity conferred by an attack of tetanus appears to be of short 

 duration. Mr. Sidney Villar, F.R.O.V.S. tells us (" Journal of Comp. 

 Path.," Dec, 1897) tlmt he "treated a black filly which recovered from an 

 attack in September, but again fell a, victim to the disease in the following 

 July." 



We have seen in Chapter III. that protection can be obtained by injecting 

 immune serum at the time of, or shortly after, infection. The action of the 

 serum is limited to destroying (or neutralising) the toxins which are in the 

 blood and those which are being manufactured by the bacilli that are located 

 in or near the wound ; but wie serum has no neutralising effect on the 

 toxins which have become fixed in the brain (Carougeau). Hence, the 

 longer ' its application is delayed, the less efficacious will it be. In places 

 where tetanus is common, it is evidently wise to use protective inoculation 

 against this disease in cases of wounds which, like those of castration, 

 punctured feet, Ac, are, under ordinary circumstances, frequently followed 

 by tetanus, and which cannot be treated antiseptioally. There should, as 

 we have seen, be no delay in applying this means of protection. Nocard 

 recommends an injection of about ^5 oz. (20 cubic centimetres) of immune 

 serum under the loose skin of the neck or shoulder, and repeated after an 

 interval of a fortnight. The period of immunity obtained from the injection 

 of anti-toxin serum, is more or less proportionate to the dose, and lasts 

 from a fortnight to six weeks. It can, however, be prolonged indefinitely 

 by successive injections. 



PREVENTIVE TREATMENT.— The remarks already made 

 about the microbe of tetanus will show the necessity of treating 

 wounds antiseptioally (p. 67) as far as possible, especially in places 

 where this disease is common. Although the spores of tetanus are 



