Mare. Vulvar swelling eight or nine days after service, with ejection of urine in jets, contraction of the vulva, redness, swelling and erection of the clitoris, and a muco-purulent discharge are marked symptoms. European observers note nodules, vesicles and ulcers on the mucosa and adjacent skin, but these were not observed in the American cases (Williams). Yet later they showed the characteristic white spots. Switching of the tail, stamping of the hind feet and painful straining to urinate are followed in certain cases by ejection of the urine forcibly in jets or in small dribblets. The catarrhal discharge is at first watery, but later becomes viscid, sticky and white, yellow or grayish, or even red. It mats together the hair of the tail and thighs, and putrefies, exhaling a repulsive odor. The swelling involves the space between the thighs and often implicates the mammary glands and even the floor of the abdomen. The inguinal glands are often involved, and hyperplasias with degenerations and even abscesses may appear in this region. As in the stallions the local lesions may have periods of advance and subsidence, and in favorable cases, that are not again served, there may seem to be a temporary recovery. The mare, however, remains infecting, and if served the local disease is at once roused into activity. The button-like skin eruptions appears on the quarter as already noticed of the horse and in grave cases may caseate or suppurate and burst, forming an indolent and intractable sore. The dark skin of the vulva and perineum becomes marked by white spots or by irregular patches caused by the confluence of several such spots, which for ordinary breeds of horses are highly characteristic of this disease. Many Arabian horses naturally acquire such white spots on the dark skin, and in pure Arabs and grades this appearance need not be held as evidence of dourine.
Infected mares rarely conceive, and any that do so are likely to abort before the sixth month.
The systemic symptoms, nervous, paralytic, tremulous, dyspeptic, atrophic, cerebral and cachectic follow a similar course as in the stallion.
In grave and progressive cases the lesions of the generative organs become very marked. The lips of the vulva become rigid and distorted so that it remains constantly open and the erect clitoris continually exposed. The skin of the vulva is tense, dry and shining. Lameness is shown in one or both hind limbs, knuckling over at the fetlock, shortening of the step, planting the toe first and the heel later with a jerk, lack of balance, paresis and even inability to rise.
A disposition to trembling is common to both sexes, as is also an intolerable itching of the skin which may make the animals tear the lower parts of the limbs with the teeth. In either there may be a local paralysis of a lip, an ear, an eyelid, or some other part of the body. In both sexes the disease tends to extreme anæmia, debility and emaciation, and to infective internal inflammations (lungs, bronchia) or septic or purulent infections.
Diagnosis. From urticaria this disease is to be distinguished by the absence of lesions of the generative organs in the former, by its association with change of food and digestive disorder and by the absence of all evidence of contagion.
From glanders it is to be distinguished in the same way by its casual transmission by sexual connection only, by its restriction to breeding animals, and by the irresponsiveness of the victim to the mallein test. The progressive paresis and hebetude are valuable diagnostic phenomena.
From chronic paraplegia it is distinguished by the same prevalence in breeding solipeds only, and by its mode of transmission.
The greatest difficulty is experienced with the slight and comparatively occult cases, and in some of these the history of the infection of a number of breeding animals, which have been served by the same horse may be the one guiding point for a number of the cases. For sanitary purposes it is well to treat as suspicious animals all mares that have been served by a stallion which is in the line of infection. This suspicion would attach also to any stallion that had served a mare which had been to a diseased or suspected stallion, and to all mares that have been served by the suspected stallion after he had been to the suspected mare.
From simple vesicular exanthema dourine is to be distinguished by its comparatively slow progress, and by the uniformity of the lesions of the generative organs and nervous system, which are lacking in the vesicular affection.