Distemper is a fever originating through infection of the system with a certain peculiar poisonous matter, the nature of which is unknown. By some it is denominated the specific, catarrhal fever of the dog; the name being suggested by the inflammation of the mucous structure which characterizes the affection.

Causation

When contagion plays so important a part, the existence of a specific germ must be admitted for a disease so clearly defined and so well characterized. Accepting this theory we reach the natural conclusion that distemper never originates spontaneously, but is dependent upon a transmission, a continued propagation of the disease poison. Some writers found sufficient explanation for the origin of the affection in exposure to damp and cold, ill ventilated kennels, poor food, improper feeding and the like, but as ideas have gradually developed and important advances have been made in tracing to fixed conditions of truth the origins of certain diseases, once believed to have originated by equivocal generation, we can scarcely doubt the doctrine of continuous propagation, and can no longer realize how every considerable deviation from a proper observance of the laws of health should be followed by the production of a particular disease.

That influences which tend to debilitate are potent factors in the extension of the disease is not questioned, but that it originates only when the specific germ of the disease exists by itself, or has been introduced, must be believed.

The poison of distemper can be conveyed from one dog to another by. contact; but it is true that direct contact is not a necessary condition for transmission; it can be conveyed by the air and in many other ways.

Hunting in his admirable treatise on this disease states: - " There are certain circumstances favorable to its origin - the congregation together of large numbers of dogs, the transit of dogs through the same places and in the same vehicles, contact with strange dogs - all of which are simply facilities for the conveyance and transmission of the specific poison of the disease. In kennels of hounds the most common time for outbreaks of distemper to appear is when the young entries arrive, i, e., when the young hounds which have been farmed out at various places, return home. Any of these may hare been in contact with a dog suffering from distemper, and if one be infected all in contact with it suffer. The possibilities of the introduction of disease are in exact proportion to the number of places from which the animals are collected. Dog shows are a fruitful cause of the spread of distemper. No matter how well managed they may be, the mere fact of collecting from various places a vast number of dogs, renders a large show almost certainly a focus from which the disease is disseminated widely. In some cases a large show has been the means of infecting nearly every puppy sent to it. The malady is not at once made evident, but shows itself a few days after the return of the animals. This cannot altogether be prevented. Dogs just convalescent and free from any apparent disease are sent to shows, and are capable of communicating distemper to others. Even healthy dogs having an immunity from the disorder, because of a previous attack, may carry the disease in their coats if they have been in recent contact with a diseased dog, and so spread the malady without ever being suspected. Some of these risks might be obviated by requiring all exhibiters to state that for one month previously their kennels have been free from contagious disease, and that their dogs have not been in contact with diseased dogs for a week anterior to the show. Railway boxes, hampers and portable kennels are sources of possible contagion which might be lessened were disinfection and washing mora methodically carried out. Distemper can be easily transmitted from a diseased to a healthy dog by a nasal discharge. It is often spread by means of the food which a diseased dog has left. Its contagiousness probably no one disputes, but most men believe that there are cases which rise independently of any contagion. The basis of such a theory is the faot that in some cases the exact method of communication is not traceable. Until a case can be found under circumstances which render the conveyance of the specific poison an impossibility, this theory has absolutely no facts to support it. The method of communication of diseaces is often difficult to trace; we can satisfactorily account for ninety case out of a hundred by contagion, and it can hardly be called begging the question to any that the odd ten, presenting the same sign, running the name course, and being equally contagious, are due to the same cause that actuated the ninety,"

In accepthing theory of the existence of a specific poison, and that Hatemper can only be communicated by contagion, the alleged causative conditions, such as exposure, debility, improper feeding, in ventilated kennels etc., are to be regarded no longer as exciting causes, and are to be considered only in so far as they may increase susceptibility, favor extension, and possibly determine the severity of the disease.

It is reasonable to suppose that inasmuch as the general system becomes weakened by anti-hygienic infinences, the power to resist contagion is lessened, the severity of disease is in a measure intensified, reaction and repair are retarded, and mortality is thereby increased.

The poison of distemper, as in other contagious diseases, can reproduce itself under favorable conditions to an endless degree; it retains its vitality and power of infection for a long time outside of the organism which produced it; it has no special stage of development to pass through on the way from, the affected organism to the one to be affected; but at the time of infection it is essentially in the same condition as when given up by the organism yielding it. That a simple attack of distemper success-roily overcome, imparts an immunity from it for the remainder of life, is a rule with only occasional exceptions. In explanation of the theory of immunity bestowed on man by certain contagious diseases, it has been suggested that something analagous to the ferment process takes place. If yeast is placed in a fluid containing sugar, fermentation follows; when all the sugar has been destroyed, and fermentation is complete, it cannot be produced again by a further addition of sugar; the fluid responds no longer to the action of the yeast. It is conjectural that during certain contagious diseases there is a destruction or change in the body of some chemical or constituent, the presence of which is a necessary condition for the retention or development of the disease. It is not unreasonable to suppose that in distemper something analogous takes place.

The disease under consideration has been compared by some to the typhoid fever of man; that it differs in its important symptoms, and appearances as observed after death is true, but it seems that the greatest disparity of all has been overlooked; typhoid fever belongs to the class of miasmatic contagious diseases and is propagated in an essentially different manner.

Distemper can be conveyed by contact from a diseased animal to a healthy one and produce the disease in him, while typhoid fever is not contagious in the proper sense of the word, for it is never transmitted by direct contact. On the profound difference in the mode of propagation depends the essential difference in the two diseases. A far greater analogy exists between typhus fever of man and distemper; it belongs to the same class of contagious diseases; the specific germ is evidently transmitted and propagated in much the same manner. The incubation period, the febrile stage, the duration, the self limitation, and many essential symptoms are alike peculiar to both. Although distemper attacks dogs of all ages it is more common in early life, the disease in old dogs being rarely observed, for the reason that nearly all have experienced an attack and are absolutely, or in a great measure insusceptible to the poison.