Scab of Cattle. 945 



ness. At the same time the skin ])ecomes bald, like parchment 

 or leather, stiff and wrinkled, but its surface is dry even under 

 the crusts, and in the neighborhood it is covered with bran-like 

 epidermal detritus. The severe rubbing may modify the clini- 

 cal picture to such an extent that the accompanying dermatitis 

 may cause the skin to be raw and even ulcerous. Left to itself, 

 the process spreads gradually and not by leaps and bounds as 

 is the case with sarcoptic scab ; meanwhile the animals fall away 

 in condition, they move stiffly, cows fall off in their milk supply, 

 and finally the increasing cachexia sometimes leads to the death 

 of the animal. At times the disease improves spontaneously 

 with the passage of winter, the crusts fall off, the hair grows 

 again partially, but the following w^inter the affection recurs 

 if the animals are kept in warm, damp barns, and then it as- 

 sumes a severe form; thereafter alternating improvement and 

 aggravation dependent on the time of the year may repeat 

 themselves several times (C. Miiller). The disease also occurs 

 in buffaloes and produces similar symptoms (Eoll). 



3. Dermatophagic Scab. This develops most frequently 

 in the grooves at both sides of the root of the tail where, with 

 symptoms of moderate itching, fine, dry, bran-like scales accu- 

 mulate. Sometimes the skin looks at first as if dressed with 

 varnish (Kaiser). Mange may also be observed in the fold of 

 the fetlock (foot scab) where it resembles eczematous "greasy 

 heels," but on the whole it is then a benign disease (Rabe). 

 Only in badly neglected cases it spreads from these spots of 

 predilection to the croup, loins and back, on the perineum, the 

 inner surface of the thighs, sometimes also to the scrotum or 

 udder. 



Apart from these rare cases in which also the condition 

 of the affected animals suffers, the disease is generally benign 

 and may even remain stationary for a year without injurious 

 results. Its infectiousness is also slight. In the cold season 

 the disease generally gets worse. 



Diagnosis. All three forms of scab, especially in their in- 

 cipient stages, may easily be recognized; the demonstration of 

 the mites also presents no difficulties, for they are generally 

 present in great number between the crusts and scales, while 

 the dermatocoptes mites are generally present at the periphery 

 of the diseased surfaces where the disease products are fresh. 



The Trichodectes scalaris or the Haematopinus eurj^sternus 

 also causes itching and superficial eczema, but their presence 

 may be easily recognized with the naked eye (it is to be remem- 

 bered that these parasites may also occur in mangy animals). 

 Idiopathic itching of the skin is differentiated from mange by 

 the acute onset and by its extension over considerable portions 

 of the body, and also by the negative result of microscopic 

 examination, while for eczema the more acute symptoms of in- 



