Influenza is an epidemic disease, which is characterized by catarrh of the respiratory, and often also of the digestive organs. Its attack is sudden, great and rapid weakness is developed, and fever of greater or less intensity is associated. The disease may occur among dogs, uninfluenced by the age of the animal or the season of the year.

Causation

Of the exciting causes of influenza little is known. It has not been established that there is any connection with atmospheric conditions. An essential difference is noted between this and the non-epidemic catarrh, since the latter affection is traceable to "catching cold," and follows exposure. Influenza on the other hand, prevails when catarrhal affections are rare, and it may appear in any season of the year, hot and dry, or cold and damp. Some authors assume it to be contagious, others refute the theory, and the question has remained a mooted one.

In 1872 an influenza prevailed widely among horses, and in New York alone attacked about sixteen thousand; no special causes for it were ascertained.

Symptoms

The frequent location of the disease is upon the mucous membrane of the respiratory organs, it being more rarely affected than that of the stomach and intestines.

The onset of the disease is generally sudden, marked by lassitude and shiverings, indicative of a chill. In severe cases fever soon manifests itself assuming a remittent type. The pulse varies in character being full and frequently irregular. The affection of the mucous membrane of the respiratory organs is indicated by symptoms essentially of a catarrhal nature. Most frequently is observed at first sneezing, the eyes reddened and watery, the nasal membrane swollen and reddened.

In some cases the throat becomes sore, and the catarrhal inflammation extends to the larynx and bronchi, the invasion of these parts being evinced by hoarseness and a tendency to cough. Not unfrequently in the very beginning, a cough sets in dry and disturbing, occurring in paroxysms frequently inducing vomiting. The expectoration is usually scanty but sometimes becomes more abundant later in the disease. While the physical examination of the chest is negative, the breathing frequently becomes hurried and at times the restlessness of the animal will indicate pain, probably of a pleuritic character. The digestive organs are very often affected. Loss of appetite, a coated tongue, thirst, and not infrequently vomiting and diarrhoea accompany the disease. At times however, constipation exists.

Prostration is often very marked, the animal is dull, heavy, and sleepy. It will be frequently noted that in walking about he will act stiff and lame and sometimes his movements will appear painful.

The expression of the eyes is changed in a marked degree, wearing a depressed anxious look. Late in the disease there is a tendency to dropsy of the limbs, and sometimes an effusion into the chest.

Diagnosis

To distinguish between other affections resembling influ-enza should not be difficult; the existence of an epidemic, other dogs being attacked at the same time; the great prostration from the first; the fever of a remittent type; the peculiar cough and absence of signs indicative of disease of the lungs. A consideration of these facts should make a differential and positive diagnosis easy.

Prognosis

If uncomplicated, the disease commonly ends in recovery. In old dogs and in very young puppies it runs a more severe course. The existence of other diseases, and a weakened and impoverished system would render a prognosis more unfavorable.

Treatment

The animal should be placed in a room of even temperature and well ventilated, but free from draughts. In mild cases the medicinal treatment need not be especially active. The congestion of the head can be relieved by gentle laxatives, but purgatives are contra-indicated. If the fever runs very high, quinine in three grain doses should be given every four or five hours. When the temperature has become normal the quinine may be continued in two grain doses, twice or three times daily for a time. If the laryngeal inflammation is severe, hot applications should be made to the neck, or the same rubbed well with the ammonia and camphor liniments in equal parts, and afterwards swathed in cotton or flannel.

In extremely severe cases where the breathing becomes difficult, the animal may be made to inhale steam; the water from which it is generated should be tinctured with carbolic acid, two drachms to the pint. An admirable method of keeping the air the animal breathes constantly disinfected, is to use some form of lime and carbolic acid mixed together.

An important consideration in treatment is to guard against possible failure of the vital powers, especially in old dogs and others weakened by diseases. Quinine or iron should be persisted in, and the following mixture be given. -

℞ Ammoniae Mur. ℥ ij.

Ext. Glycyrrhizae Pulv. ℥ ij Aquae ℥ iij.

Ft. Mist. Sig. Dose one teaspoonful in water every three hours.

The diet should be easily digestible; milk, broths, and if needed, eggs added to the former.

During the convalescent stage, the animal should be Judiciously exercised in the open air, but guarded against exposure.