HYDROPHOBIA.
The success of Preventive treatment had of late years been conclusively demonstrated by the immunity enjoyed by Great Britain and Ireland through the muzzling regulations, and a similar result has been achieved in other regions by rigid quarantine regulations.
Only a comparatively small proportion of human beings bitten by a rabid dog is found to develop hydrophobia, the percentage being probably under 15. For wolf bites the percentage is above 7o, and the proportion in both cases rises when the naked skin has been bitten.
The importance of cauterising the wound is obvious, and the success of this prophylactic measure will depend upon the promptness and thoroughness with which it is carried out. An extemporised tourniquet should be instantly applied upon the proximal side of the wounded site and the bite thoroughly cleansed; innumerable instances are on record where the infective process has been prevented by sucking the wound, though such a procedure cannot be regarded as free from danger where any abrasions of the mucous membrane are present.
The most effective agent for the destruction of the germs in the wound is the actual cautery, but as this is very painful caustics are more fre quently resorted to. Owing to its portability Nitrate of Silver is the one usually depended upon, being generally in the pocket-case of the veterinary surgeon and of the practitioner; it is, however, one of the least reliable and most painful of caustics. Pure Carbolic Acid thrust deeply into the wound on a piece of pointed wood is a very powerful steriliser; any caustic or corrosive substance which happens to be at hand may be employed. The thorough excision of the bitten area by the knife is recommended, but as even this heroic procedure should not justify the victim in refusing Pasteur treatment in case the suspected animal should be afterwards proved to have been suffering from true rabies, excision is unnecessary unless in such cases of extreme isolation as will prohibit a journey to the Paris or other Pasteur Institutes. Every
person bitten by an animal known to be rabitic should submit without any unnecessary delay to a course of Pasteur treatment, whether Negri bodies can or cannot be found in the cerebral nerve cells of the dog.
The rationale of treatment depends upon the long period of incubation of the disease, this being never shorter than two and often as long as Svc to ten weeks, during Nvhich period the patient can be effectually prevented from developing hydrophobia by a series of immunising injections of a modified or attenuated virus along with the toxins produced by it, pro tection being established before the symptoms of hydrophobia have time to show themselves. In a few cases the incubation has been much longer, and a period of two years in one authenticated case intervened between the reception of the wound and the invasion. The best results are obtained when the treatment is sought at the earliest stage, but in every case it should be sought, even should a month or more have inter vened. Pasteur informed the writer in 189r that on studying his atlas he found the mortality to rise with the distance which the patient had to travel from the country in which he was bitten to the Institute in Paris, being very high in those foreigners whose home was at a distance and in those whose railway facilities were very imperfect or absent.
The initial step in Pasteurism is to obtain a uniformly strong and un varying virus capable of producing death after a constant period of incubation. This " fixed " virus is stronger than that obtainable from a rabid wolf and many times more powerful than that from a rabid dog, and is procurable only after passing the latter through the bodies of too rabbits.
If the spinal cord of a rabbit killed by this virus is removed and ex posed in a sterilised jar to air deprived of moisture by the presence of caustic potash, and kept in a temperature of F., it is found that every day produces a diminution in the power of its contained virus.