356 ACUTE EXANTHEMATOUS INFECTIOUS DISEASES 



Cattle seem to be more susceptible than horses; the disease 

 is less commonly seen in sheep, goats, and swine. One attack 

 produces a transient immunity, although cases are recorded 

 where one and the same animal has been attacked repeatedly. 



Symptoms. — The period of incubation is usually from two to 

 five days. A minimum period of twenty-four hours and a 

 maximum period of nearly two weeks have been recorded. 

 The first symptoms in females are inflammation of the 

 mucous membrane of the vulva and vagina in which appear 

 small red papules which in two or three days form red, pea- 

 sized vesicles containing a clear yellow fluid. The lesions 

 are commonly found in the upper commissure of the vulva 

 and in the neighborhood of the clitoris and the mucous surface 

 of the lips of the vulva. 



Similar eruptions may invade the skin around the vulva, 

 anus, and the perineum. In a short time, from secondary 

 infection, the vesicles become pustules, which erupt, leaving 

 behind shallow ulcers which heal readily by granulation. In 

 some cases, however, the ulcers are deeper, and when they 

 heal there is left behind a white or yellow scar which in time 

 tends to disappear. In some instances after the eruption of 

 the pustule tough, yellow crusts nearly a quarter of an inch 

 thick remain. When these crusts are removed or drop off, 

 white areas remain which are usually small and circular, but 

 by confluence larger and irregular in form. 



The lips of the vulva are edematously swollen as may be 

 the surrounding parts. In mares repeated blinking of the 

 vulva is noted. There is a vaginal discharge of a mucopuru- 

 lent character which soils the tail and buttocks. 



In male animals a similar eruption appears upon the penis, 

 prepuce, and sheath. The penis itself is swollen, and from 

 the urethra flows a mucopurulent discharge. The above- 

 described depigmented areas noted in female animals are also 

 seen on the penis in males. Urination is frequent and accom- 

 panied by considerable straining, the patient often switching 

 its tail, arching the back and kicking against its abdomen. 

 In males, especially stallions, the penis is often erected and a 

 yellowish mucopurulent discharge flows from the urethra. 



Ordinarily the general condition of the animal is not im- 



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