PREVENTIVE MEDICINE 361 



colonies, if found, are usually in close proximity to the original 

 site. This particular mange is only of importance with horses, 

 and is the cause of the itchy legs so commonly seen among heavy 

 draught animals. The itching is sometimes productive of serious 

 injury from the constant stamping and kicking it causes. Usually 

 confined to the lower extremities, and especially the hind legs, it 

 sometimes spreads upwards and along the body, and cases occur, 

 with greater frequency than is generally realised, where the initial 

 lesion is in the mane, tail or part of the body. The author has seen 

 a farm horse, neglected at grass for several months, with two-thirds 

 of his body infested. The disease is said to be more prevalent in 

 winter than in summer. 



Psoroptic and sarcoptic mange of the horse, mule and ass and 

 psoroptic mange of sheep are the only forms of the disease that are 

 scheduled as notifiable. 



Methods of Transmission. Mange of the horse, ass and mule 

 is spread by direct contact between diseased and non-affected 

 animals and by numerous indirect media, among the most important 

 of which are the harness, clothing, bedding, grooming tools, stalls 

 and their fittings, and the door-posts against which animals are 

 liable to rub in passing to and from the stable. The under face 

 of mangers and hay-racks are especially liable to hold the parasites 

 owing to these being favourite places for horses to rub their necks 

 and manes on. The shafts of carts must also be considered as pos- 

 sible receivers of the parasites, though probably retaining them only 

 for a short period. The shoeing forge must always be regarded as 

 a centre from which the disease is disseminated, and probably the 

 shoeing-smith's apron is the most common indirect medium for 

 transmitting symbiotic mange. Mange is commonly introduced 

 into a clean stable by the purchase of an affected animal, and its 

 presence may not be detected until several of the horses have 

 become obviously itchy. A mangy horse put up at a livery stable, if 

 only for an hour or so, may be the cause of a lot of trouble, 

 especially if it is groomed. 



PREVENTIVE MEASURES. Despite all precautionary measures, 

 mange sometimes finds its way into a stable but, as a rule, its appear- 

 ance among a clean stud of horses is due to carelessness. Most 

 commonly its introduction is due to the purchase of a slightly 

 infected animal, therefore care should be taken to examine in- 

 tended purchases for any suspicious symptoms of the disease. 

 Itchiness of the skin may of course be due to other causes than 

 mange, such as lice, dirt, or to the presence of certain of the forage 

 acari. If no mange acari are found and there is no other obvious 



