582 THE DISEASES OF THE llOKSE 



CHAPTER XXXI 



SKIN DISEASES 



MANGE— MCE— POULTRY LOUSINESS— RINGWORM— ECZEMA— ITCHY TAH.— MALLENDERS 

 AND SALLENDERS— UARNESS GALLS AND SITFASTS— CUAITED OR CRACKED UEELS — 

 SWELLED LEGS— WARTS. 



Many of these are troublesome and annoying both to the horse and his 

 rider, and the causes of some of them are still obscure. As they usually yield 

 to treatment, and it is not necessary for us to enter minutely into their 

 pathology, we will briefly consider those likely to be met with by the horse- 

 man 



MANGE 



Tins SCOURGE OF THE STABLE and of armies on the march, is caused by a 

 parasite similar to that Avhich causes itch in man, scab in sheep, and mange 

 in dogs. It is extremely contagious, and is communicable by stall-posts and 

 mangers as well as by actual contact of one animal with another. The 

 irritation which they set up is caused in their quest for food, as they first 

 bite the skin, and then introduce a poisonous principle which causes the 

 serum of the blood to come up in little vesicles, and upon these they feed. 

 There are three varieties of this insect with somewhat diflerent habits. 



1. The Dermatodectes or Psoroptes is the most common in Britain. 

 These prick the skin only and revel in the scabs that result, the mane and 

 tail having a special attraction for them. A large proportion remaining on 

 the surface, their presence is easily determined by scraping and examining 

 with a lens of moderate power. The irritation set up is intolerablo, and the 

 host is to be found constantly rubbing against every available object until 

 the skin is hairless, raw and wrinkled. In some countries it is known as 

 " sweet itch," and its contagious nature not properly appreciated because the 

 habits of the parasite are such that he remains in a locality only so long as 

 there is plentiful food. In this respect he differs greatly from the second 

 variety, which is full of tcanderlust, and known as 



2. Sarcoptes. — This is essential!}^ a burrower, not living on the surface, 

 but tunnelling in every direction, and the subject of his ravages may be 

 covered with mange in a week or two. The skin lias the appearance of 

 innumerable pimples, which, if carefull}' examined, will be foand to consist 

 of a tiny scab, to which a few hairs are adherent ; when scratched oflF a 

 small red sore is left. With constant rubbing the hairs come out, the skin 

 becomes wrinkled, dry, and shrivelled, and there is loss of condition and 

 spirits, as the victim gets little rest or sleep if badly attacked. As with all 

 parasites, whether of animals or plants, there are seasons in which they are 

 particularly active and aggressive, causing even the death of their hosts. 

 Among Shetland ponies, sarcoptic mange takes on such a severe form as from 

 time to time to destroy considerable numbers, and among the horses of a 

 great London distributing company a few years ago, a number died or had 



