198 THE HORSE 



on the back, at the set-on of the tail and on the quarters, 

 in which places the hair is long and the skin very often 

 dirty. All mange parasites are of microscopic size and 

 require the skilled use of the microscope for their detection. 

 They are"" closely allied to forage acari and very often 

 confused with these organisms. Forage acari would 

 appear to be capable of inducing a certain amount of 

 skin irritation. They exist in the dust of forage, hay, etc. 

 The commonest form of mange is the psoroptic, and it is 

 more communicable from horse to horse than the sar- 

 coptic. The three different forms of mange may co- 

 exist in the same animal at the same time, and, in addi- 

 tion, Hce may be present, materially aggravating the skin 

 irritation. 



The earhest indication of mange is irritation of the 

 skin as shown by the animal rubbing or biting the part, if 

 accessible for the latter purpose. This leads to the loss of 

 hair in patches, and as the disease extends the patches 

 become confluent, so that in course of time, more especially 

 if the trouble is neglected, the body becomes more or 

 less denuded of hair. In advanced cases of mange the 

 pruritis, or irritation, is intense, and, as this leads to 

 exhaustion, loss of flesh follows, and the animal may 

 succumb in consequence. 



Mange is, as previously stated, one of those troubles 

 which are favoured by uncleanliness, and its progress is 

 more rapid amongst horses which are over-crowded, 

 badly groomed, and neglected in various other ways. 

 Dirt evidently favours the perpetuation of the parasites. 

 It is important to know that the adult female sarcopt 

 lays her eggs at the end of a tunnel or gallery formed 

 beneath the superficial layers of the skin, and that these 

 eggs hatch out and produce larvae in from four to six 

 days. Further, that the larva form takes from eight to 

 ten days to develop into the adult, wliich is then ready to 

 perpetuate the parasites in its turn. The ova are much 

 more tenacious of vitality than the actual parasites, and 



