Chapter 66

The nodules, which are first red and hard and consist of new connective tissue, soon soften and become yellow; the yellow spots break and we have a small ulcer the size of the preceding nodule, which has a gray, dirty bottom and ragged edges and is known as a chancre. This ulcer pours from its surface a viscous, oily discharge similar to that which we have seen in the farcy ulcer. The irritation of the discharge may ulcerate the lining mucous membrane of the nose, causing serpentine gutters with bottoms resembling those of the chancres themselves. If the nodules have formed in large numbers, we may have them causing an acute inflammation of the Schneiderian membrane, with a catarrhal discharge which may mark the specific discharge, or that which comes from the ulcers and resembles the discharge of strangles or simple inflammatory diseases.

The eruption of the ulcers and discharge soon cause an irritation of the neighboring lymphatics; and in the intermaxillary space, deep inside of the jaws, we find an enlargement of the glands, which for the first few days may seem soft and edematous, but which rapidly becomes confined to the glands, these being from the size of an almond to that of a small bunch of berries, exceedingly hard and nodulated. This enlargement of the glands is found high on the inside of the jaws, firmly adherent to the base of the tongue. It is not to be confounded with the puffy, edematous swelling, which is not separated from the skin and subcutaneous connective tissues found in strangles, in laryngitis, and in other simple inflammatory troubles.

These glands bear a great resemblance to the indurated glands which we find in connection with the collection of pus in the sinuses; but in the latter disease the glands have not the extreme nodulated feel which they have in glanders. With the glands we find indurated cords, feeling like balls of tangled wire or twine, fastening the glands together.

The essential symptoms of glanders are the nodule, the chancre, the glands, and the discharge. With the development of the nodules in the respiratory tract, according to their number and the amount of eruption which they cause, we may find a cough which resembles that of a coryza, a laryngitis, a bronchitis, or a broncho-pneumonia, according to the location of the lesions. In chronic glanders we find the same accessory symptoms that occur in chronic farcy, the hemorrhage of the nose, the swelling of the legs, the chronic cough, and, in the entire horse, the swelling of the testicles.

On healing, the chancres on the mucous membranes leave small, whitish, star-shaped scars, hard and indurated to the touch, and which remain for almost an indefinite time. The chancres heal and the other local symptoms disappear, with the exception of the enlargement of the glands, and we find these so diminished in size that they are scarcely perceptible on examination. During the subacute attacks, with a minimum quantity of local troubles, in chronic glanders and in chronic farcy the animal rarely shows any degree of fever, but does have a generally depraved appearance; it loses flesh and becomes hidebound; the skin becomes dry and the hairs stand on end. There is a cachexia, however, which resembles greatly that of any chronic, organic trouble, but is not diagnostic, although it has in it certain appearances and conditions which often render the animal suspicious to the eye of the expert veterinarian, while, without the presence of local lesions he would be unable to state on what he has based his opinion.

ACUTE GLANDERS.

_Symptoms._--In the acute form of glanders we find the symptoms which we have just studied in chronic farcy and in chronic glanders in a more acute and aggravated form. There is a rapid outbreak of nodules in the respiratory tract which rapidly degenerate into chancres and pour out a considerable discharge from the nostrils. There is a cough of more or less severity according to the amount and site of the local eruption. Over the surface of the body swellings occur which are rapidly followed by farcy buttons, which break into ulcers; we find the indurated cords and enlargement of the lymphatics.

Bleeding from the nose, sudden swelling of one of the hind legs, and the swelling of the testicles are liable to precede an acute eruption of glanders. As the symptoms become more marked the animal has difficulty of respiration, the flanks heave, the respiration becomes rapid, the pulse becomes quickened, and the temperature becomes elevated to 103°, 104°, or 105° F.

With the other symptoms of an acute fever the general appearance and station of the animal is that of one suffering from an acute pneumonia, but upon examination, while we may find sibilant and mucous râles over the side of the chest, and may possibly hear tubular murmurs at the base of the neck over the trachea, we fail to find the tubular murmur or the large area of dullness on percussion over the sides of the chest which belongs to simple pneumonia.

_Diagnosis._--When there is doubt as to the diagnosis, the mallein test, the inoculation test, or the complement-fixation test may be employed. The mallein test is made by injecting mallein (a sterilized extract from a culture of glanders bacilli) beneath the skin. If the horse has glanders there results a febrile reaction and a swelling at the point of injection. If the horse does not have glanders the mallein has no effect or, at most, it produces a slight swelling only at the point of injection. The inoculation test consists in the inoculation of a susceptible animal (usually a guinea pig) with some of the suspected discharge from the nose or a farcy ulcer. If the material is properly used, and if it contains bacilli of glanders, the experimental animal will develop the disease.

The eye test is now universally accepted as a very satisfactory means of diagnosing glanders. This consists in dropping into an eye of a suspected animal a specially prepared solution of mallein, as a result of which in an infected animal the inflammation develops in the eye, resulting in a discharge which varies in intensity from a mucopurulent character to a thick, sticky pus. The eyelids may also swell and many times become glued together. The reaction usually appears in from 8 to 20 hours after the introduction of the mallein.

Neither of these tests should be put into use except by a competent veterinarian. The complement-fixation test is a highly specialized laboratory test and can be carried out only by one versed in laboratory technique. (See Bureau of Animal Industry Bulletin 136.)

The post-mortem examination of the lungs shows that the pneumonia of glanders is a lobular, V-shaped pneumonia scattered throughout the lungs and caused by the specific inflammatory process taking place at the divergence of the smaller air tubes of the lungs. In some cases of acute glanders the formation of nodules may so irritate the mucous membrane of the respiratory tract and cause such a profuse discharge of mucopurulent or purulent matter that the specific character of the original discharge is entirely masked. In this case, too, for a few days the submaxillary space may so swell as to resemble the edematous, inflamed glands of strangles, equine variola, or laryngitis. This condition is especially liable to be marked in an acute outbreak of glanders in a drove of mules.

Cases of chronic farcy and glanders, if not destroyed, may live in a depraved condition until the animal dies from general emaciation and anemia, but in the majority of cases, from some sudden exposure to cold, it develops an acute pneumonia or other simple inflammatory trouble which starts the latent disease and the animal has acute glanders.

In the ass, mule, and plethoric horses acute glanders usually terminates by lobular pneumonia. In other cases the general symptoms may subside. The symptoms of pneumonia gradually disappear, the temperature lowers, the pulse becomes slower, the ulcers heal, leaving small, indurated cicatrices, and the animal may return to apparent health, or may at least be able to do a small amount of work with but a few symptoms of the disease remaining in a chronic form. During the attack of acute glanders the inflammation of the nasal cavities frequently spreads into the sinuses or air cells, which are found in the forehead and in front of the eyes on either side of the face, and causes abscesses of these cavities, which may remain as the only visible symptom of the disease. An animal which has recovered from a case of acute glanders, like the animals which are affected by chronic glanders and chronic farcy, is liable to be affected with emphysema of the lungs (heaves), and to have a chronic cough. In this condition it may continue for a long period, serving as a dangerous source of contagion, the more so because the slight quantity of discharge does not serve as a warning to the owner or driver as profuse discharge does in the more acute cases.

At the post-mortem examination of an animal which has been destroyed or has died of glanders we find evidences of the various lesions which we have studied in the symptoms. In addition to this, we find nodules similar to those which we have seen on the exterior throughout the various organs of the body. Nodules may be found in the liver, in the spleen, and in the kidneys. We may find inflammation of the periosteum of the bones, and we have excessive alterations in the marrow in the interior of the bones themselves. Both these conditions during the life of the animal may have been the cause of the lamenesses which were difficult to diagnose.

In one case which came under the observation of the writer, a lame horse was destroyed and found to have a large abscess of the bone of the arm, with old nodules of the lungs. When an animal has died immediately after an attack of a primary, acute case of glanders, we find small V-shaped spots of acute pneumonia in the lungs. If the animal has made an apparent recovery from acute glanders, and in cases of chronic farcy and chronic glanders, no matter how few the external and visible symptoms may have been, there is a deposit of nodules--small, hard, indurated nodes--of new connective tissue to be found in the lungs. When these have existed for some time we may find a deposit of lime salts in them. These indurated nodules retain the virus and their power to give out contagion for almost an indefinite time, and predispose to the causes which we have studied as the common factors in developing a chronic case into an acute case; that is, an inflammatory process wakens their vitality and produces a reinfection of the entire animal. The blood of an animal suffering from chronic glanders and farcy is not virulent and is unaltered, but during the attack of acute glanders, while the animal has fever, the blood becomes virulent and remains so for a few days.

_Treatment._--Almost the entire list of drugs in the pharmacopoeia has been tested in the treatment of glanders. Good hygienic surroundings, good feed, with alteratives and tonics, frequently ameliorate the symptoms, and often do so to such an extent that the animal would pass the examination of any expert as a perfectly sound animal. While in this case the number of nodules of the lungs, which are invariably there, may be so few as not to cause sufficient disturbance in the respiration as to attract the attention of the examiner, yet they exist, and will remain there almost indefinitely, with the constant possibility of a return of acute symptoms.

It is probable that some horses may recover from glanders if the infection is slight, but it will not do to depend upon this except under the most stringent veterinary supervision. With good care, good feed, good surroundings and little work, an animal affected with glanders may live for months or even years in a state of apparently perfect health, but with the first deprivation of feed, with a few days of severe hard work, with exposure to cold or with the attack of a simple fever or inflammatory trouble from other causes, the latent seeds of the disease break out and develop the trouble again in an acute form.

In several celebrated cases horses which have been affected with glanders have been known to work for years and die from other causes without ever having had the return of symptoms; but allowing that these cases may occur, they are so few and far between, and the danger of infection of glanders to other horses and to the stable attendants is so great, that no animal which has once been affected with the disease should be allowed to live unless repeated mallein tests have shown him to have become free from taint of glanders.

In all civilized countries, with the exception of some of the States in the United States, the laws are most stringent regarding the prompt declaration on the part of the owner and attending veterinarian at the first suspicion of a case of glanders, and they allow indemnity for the animal. When this is done, in all cases the animal is destroyed and the articles with which it has been in contact are thoroughly disinfected. When the attendants have attempted to hide the presence of the disease in a community, punishment is meted out to the owner, attending veterinarian, or other responsible parties. Several States have passed excellent laws in regard to glanders, but these laws are not always carried out with the rigidity with which they should be.

SPOROTRICHOSIS (MYCOTIC LYMPHANGITIS).

By JOHN R. MOHLER, V. M. D., _Assistant Chief, Bureau of Animal Industry_.

This disease has previously been known in this country as epizootic lymphangitis, or pseudo-farcy. It is a chronic, contagious disease, particularly of equines, caused by a specific organism, the _Sporotrichum schenckii_, and characterized by a suppurative inflammation of the subcutaneous lymph vessels and the neighboring lymph glands. Owing to the fact that this affection does not spread as an epizootic and that its causal factor is a fungus, the name sporotrichosis has been suggested.

The disease in man was first described by Schenck and by Beurmann and Gougerot. Carougeau observed its occurrence among horses and mules in Madagascar, while in the United States it was first observed by Pearson in Pennsylvania in 1907, although it is probable that it had existed for many years in various parts of this country. Page and Frothingham were first to recognize its mycotic nature in the United States. More recently Meyer has also made valuable contributions with regard to the existence of this affection. Its presence has been definitely established in Ohio, Iowa, California, and North Dakota, and there is a probability of its existence in Indiana and several Western States.

_Bacteriology._--The sporotrichum is 2 microns thick, cylindrical and segmented, having more or less branching threads, which bear spores at the end. In the pus they occur as slightly ovoid bodies 3 to 5 microns long, which are somewhat pointed toward the poles, have a sharp double contour, and only on artificial cultivation at a temperature of over 18° do they develop into the characteristic spore-carrying threads.

The period of incubation varies greatly, extending from three days to four months, or even longer. In artificial inoculations with pus through wounds in the skin, inflammation and swelling of the lymph vessels may be noticed in ten to sixty days; these vessels show in their course a development of hard nodules, from which abscesses form.

The natural infection without doubt is caused through superficial wounds, such as galls, barbed-wire cuts, or through various stable utensils, harness, bandages, insects, etc. Solipeds are mostly susceptible, but cattle may also be infected.

_Symptoms._--The inflammation of the lymph vessels is usually first observed on the extremities, especially on one or both hind legs; it may also appear on the forelegs, shoulder, or neck, and more rarely on the rump, udder, and scrotum. The lesions, as a rule, develop in the tissue adjacent to the place of inoculation. In the early stages of the disease the lymph vessels appear very hard and thickened, and along their course hard nodules develop, ranging in size from a pea to a hen's egg. Later these nodules soften, burst spontaneously, and discharge a thick, yellowish pus. The surface of the resulting ulcers or abscess cavities soon fills up with exuberant granulations which protrude beyond the surface of the skin, giving it a fungoid appearance. The affected extremities are considerably enlarged, similar to cases of simple lymphangitis. In rare cases the mucous membrane of the nostrils may also become affected, showing yellowish flat elevations and ulcerations, and these may extend by metastasis to internal organs. In cases in which the mucous membrane is affected, the submaxillary lymph gland may also become enlarged and suppurate.

The constitutional symptoms accompanying this disease are not very marked and may be altogether absent. There is usually only a very slight fever, which seldom runs over 102° F. The appetite is not impaired except in the advanced cases.

_Lesions._--The anatomical changes are most marked in the skin and the subcutaneous tissues. They may become 2 to 3 inches thick and indurated as the result of fibrous-tissue formation, owing to the inflammation present. On the baconlike cut surface suppurative areas and granulating sores may be noticed of various sizes, also enlarged lymph vessels filled with clotted lymph mixed with pus. The neighboring lymph glands are usually enlarged and frequently contain suppurating foci. Rarely the internal organs may show metastatic abscesses.

_Diagnosis._--The diagnosis is based on the characteristic appearance of the ulcerations, which show exuberant granulation of a bright red color, inverted edges, and a thick, creamy, glutinous discharge. These manifestations differentiate the disease from glanders, in which the ulcers are craterlike, do contain exuberant granulations, and the discharge is of a viscous, oily character. The submaxillary and other nodes as well as the corded lymphatics in glanders are more firmly attached to the adjacent tissues, and are therefore less movable. In some chronic cases of sporotrichosis, however, the lesions may closely resemble those of farcy, and in these cases the microscopical examination of the pus will disclose the nature of the affection. In the pus the causative organism can be easily seen in the unstained specimen, and is recognized by its size, shape, and highly refractory double outline. Furthermore, the injection of mallein in cases of sporotrichosis will be attended with negative results.

_Treatment._--At the onset of the disease treatment consists in entire extirpation of the nodules, in case the lesions are localized. In cases in which the nodules have formed abscesses, their opening is recommended, followed by the application of the actual cautery or a 1 to 250 solution of bichlorid of mercury. It must be borne in mind that the organism is quite resistant to antiseptics, and the best results will be obtained from the application of a solution of a strong antiseptic following the opening of the lesions. Internally, potassium iodid is recommended in 2-dram doses, dissolved in drinking water, twice a day.

In the most favorable cases recovery results in from five to seven weeks; as a rule, however, it requires several months.

In order to prevent the spreading of the disease the affected animals should be isolated, the products of the disease should be destroyed, and the stable should be disinfected with very strong liquid disinfectants in consideration of the resistance of the causative organism.

RABIES, HYDROPHOBIA, OR MADNESS.

Rabies is a contagious disease, which is usually transmitted by a bite and by the introduction of a virus contained in the saliva of an affected animal. It may, however, be transmitted in other ways. It is characterized by symptoms of aberration of the nervous system and invariably terminates fatally. It is accompanied with lesions, inflammation, and degeneration in the central nervous system. It is a disease that is most common in the dog, but is transmitted to the horse, either from dogs or from any other animal affected with it. (See also remarks on page 244.) As a disease of the horse it is invariably the result of the bite of a rabid animal, usually a dog.

Perhaps no disease in medicine has been the object of more controversy than rabies. Certain medical men of prominence have even doubted its existence, and many others have claimed for it a spontaneous origin. The experience of ages, however, has shown that contagion can be proved in the great majority of cases, and, by analogy with other contagious diseases, we may only believe that the development of one case requires the preexistence of a case from which the virus has been transmitted. Pasteur has further added to our knowledge of the disease by showing that a virus capable of cultivation exists in the nervous system, especially in the lower part of the brain (medulla oblongata) and in the anterior part of the spinal column. He has further shown that that portion of the nervous system which contains the virus, the exact nature of which has not yet been demonstrated, will retain it for a very long time if kept at a very low temperature or if left surrounded by carbolic acid; but if the nerve matter, which is virulent at first, is exposed to the air and is kept from putrefaction by substances which will absorb the surrounding moisture, it will gradually lose its virulence and become inoffensive in about fifteen days. He has also further shown that the action of a weak virus on an animal will prevent the development of a stronger virus, and from this he has formulated his method of prophylactic treatment. This treatment consists in the successive inoculation of portions of the nerve matter containing the virus from a rabid animal which has been exposed to the atmosphere for thirteen days, ten days, seven days, and four days, until the virulent matter which will produce rabies in any unprotected animal can be inoculated with impunity. A curious result of the experiments of Pasteur is that an animal which has first been inoculated with a virus of full strength can be protected by subsequent inoculations of attenuated virus repeated in doses of increasing strength.

Innumerable attempts have been made to discover the causative agent, and investigators have announced the finding of many of the lower forms of animal and vegetable life as the pathogenic factor. Among the recently described causes, certain protozoanlike bodies found in the ganglionic cells in 1903 by Negri, and termed Negri bodies, are of a very suggestive nature. Negri claims that these bodies are not only specific for rabies, but that they are protozoa and the cause of the disease. His work has been corroborated by investigators in all parts of the scientific world. An examination of the vitality of these bodies will show a striking resemblance to the vitality of an emulsion of the virulent tissue. Thus, they have been found to be quite resistant to external agencies, such as putrefaction, drying, etc., and are about the last portion of the nerve cell to survive the advance of decomposition. They are also found in more than 96 per cent of the cases of rabies examined, but have not been proved to exist in other diseases.