28o CLINICAL VETERINARY MEDICINE AND SURGERY. 



frequent in both sexes, but is particularly common during the second 

 half of life. Apart from the eruption of distemper, young dogs seldom 

 show more than ephemeral vesicular outbreaks quite different from the 

 ec2ema of aged animals. The disease does not attack all regions with 

 equal frequence, appearing to have a preference for the upper parts of 

 the body like the head, neck, back, loins, and croup, and for the point 

 of the elbow, groin, scrotum, tail, and interdigital spaces. When 

 chronic and of old standing it may be more or less generalised. Then 

 it is usually exceedingly rebellious about the back, elbows, hocks, in 

 the ear, and at the extremity of the tail. 



At the beginning of any summary of the conditions favourable to 

 the outbreak of eczema must be mentioned that important idea that 

 eczematous eruptions are often subordinate to a constitutional condi- 

 tion or diathesis ; in the case of young dogs to a lymphatic tempera- 

 ment, in adults and the aged to a gouty diathesis, to obesity, and 

 sometimes to diabetes. This general condition largely determines the 

 occurrence of the disease, and demands special treatment : in certain 

 subjects it produces disturbance in the functions of the stomach, 

 intestine, and liver, mal-assimilation accompanied by auto-intoxica- 

 tion ; conditions which favour the development of eczema, render it 

 liable to appear under the influence of trifling causes, and may even 

 constitute the primary factor. Many animals with rebellious eczema 

 are also affected with chronic bronchitis, emphysema, or asthma ; and 

 eczematous attacks not infrequently alternate with certain affections of 

 the digestive or respiratory apparatus. Feeding also plays a part in 

 the development of eczema : depending on the conditions under which 

 the animal lives, attacks may be produced either by an exclusively 

 vegetable or exclusively meat diet. 



Eczematous eruptions are generally preceded by cutaneous irrita- 

 tion of variable character and intensity. They may be caused by 

 clipping, repeated rubbing, pressure of the collar, the action of alka- 

 line or acid solutions, or by external parasites affecting the parts which 

 most commonly become diseased. Want of cleanliness and accumula- 

 tion of dust or sebaceous secretions on the surface may readily bring 

 about outbreaks. In certain cases, on the other hand, they may result 

 from excessive use of soap and warm or cold water. During the 

 summer they are not infrequently produced by the action of the sun's 

 rays on the skin. 



The part played by the circulatory and nervous apparatus in the 

 genesis of eczema is still obscure. In dogs the symmetrical, slowly 

 developing eruptions, apparently of nervous origin, are rare. 



