Erythema. Erythematous Dermatitis. 465 



Counter-irritation over the vaso-motor centres, is often of 

 value, when the distribution of the eruption coincides with that 

 of particular nerves, and indicates a nervous element in the 

 causation. 



Bandages of various kinds may be demanded to afford sup- 

 port in threatened dropsical effusion or excessive granulation or 

 In^perplasia, to protect the surface against outside infection, to 

 confine volatile applications to the affected part, and to prevent 

 injury from biting, licking, scratching, or rubbing. 



For the same reason it may be desirable to employ a muzzle, 

 beads on the neck, tying to two opposite rings by short halters, 

 hobbles, or other means of restraint. 



ERYTHEMA. ERYTHEMATOUS DERMATITIS. 



Definition, congestion, heat, redness, tenderness withont eruption. Sheep : 

 swine : dogs : white horses and cattle. Causes : sHght irritants. Symp- 

 toms : congestion momentarily effaced by pressure, may go on to a distinct 

 irruption. 



Definition. Congestion of the papillary and adjacent layers of 

 the skin with heat, redness, and tenderness, or a diffuse super- 

 ficial inflammation with some superadded swelling. 



Genera stisceptible. The affection is seen in sheep, swine, 

 dogs, and in wliite horses and cattle or on white parts of the 

 skin. It is not readily recognized on pigmented parts. 



Causes. The action of any slight irritant : pressure, friction, 

 bru.shing, currying, blows, vesicants, rubefacients, stings, para- 

 sitism, radiant heat, intense sunshine, cold (reaction), storm, 

 plunging in cold streams when heated, feeding on stimulating 

 agents, notably buckwheat. 



Sympto7?is. On white skins there is a uniformly diffused red- 

 ness, without papule or other eruption, and the color may be 

 momentarily effaced leaving a perfectly white spot, made by the 

 pressure of the finger. The affected part is warm, tender, and 

 it may be, itchy. It may be but the first .step of a distinct erup- 

 tion of another kind, such as variola, vesicles, papules, pustules, 

 but then the affection takes a different name. It has been 

 named according to its seat, cause and nature as follows : 



30 



