PSOROPTIC MANGE. 639 



not improbable that some or all of these were cases of this sarcoptic 

 mange, and in view of its very contagious character it is desirable 

 that care should be taken to exclude from shows animals exhibiting 

 any symptom of the disease. 



PSOROPTIC MANGE. 



This condition has also been termed dermatodectic mange. This 

 is very rare, and, like the former, of trifling clinical importance. 



Causation. It is due to infection with Psoroptes communis (r. hovis). 

 Poor condition, want of grooming, bad hygienic surroundings and 

 general neglect, facilitate its spread. 



Symptoms. It commences at the base of the neck, in rarer cases 

 at the sides of the neck, along the withers, and at the root of the 

 tail; thence it gradually attacks the croup, loins, back, shoulders, 

 sides of the chest, and finally all the body with the exception of the 

 limbs. 



It produces violent itching, the animal continually scratching itself, 

 even causing raw sores. At first the epidermis is elevated in little 

 miliary points, which may be isolated or confluent, and are filled 

 with serosity. This fluid discharges, gluing together the hairs ; it 

 then hardens and produces adherent crusts, which increase in num- 

 ber and size. The skin exhibits large numbers of bare, mangy points ; 

 these have irregular margins, and are covered with thick, grey, scal}^ 

 crusts. The psoroptes are found under these crusts. 



The skin becomes hard, dry, fissured and cracked, and sometimes 

 forms large folds on the sides of the neck, shoulders and chest. 



The influence of the seasons on the development of this disease 

 has been well shown by Gerlach and MuUer. The disease commences 

 about the end of autumn, when the animals are stabled. It continues 

 to extend until February, but diminishes as soon as the animals re- 

 turn to the fields in spring. The crusts fall, the hair again grows, 

 and the animal appears to be cured, but the disease again revives 

 during the autumn. The psoroptes lie hidden during the summer 

 round the poll and the horns. The disease seldom attacks animals 

 at grass and in good condition, or those over three years old. Calves, 

 yearlings, and two-year-olds in poor condition suffer most. 



When the disease is verj^ extensive, the animals lose condition 

 and may even die. 



Diagnosis. Psoroptic mange in the ox may be mistaken for several 

 cutaneous diseases, to which it has a certain resemblance, as for instance 

 phthiriasis and the first stage of ringworm. 



These different diseases, however, show their own distinctive symp- 

 toms on a careful examination. 



