POULTRY DISliASES AND THEIR TREATMENT. I43 



feathers on different parts of the body. It usually begins at the 

 rump and spreads to the head and neck, back, thighs and breast. 

 The large wing and tail feathers are not usually lost. The ex- 

 posed skin is normal in appearance. Around the stumps of the 

 lost feathers and at the end of the quills of feathers near the 

 bare spots are masses of epidermal scales. On microscopic 

 examination these scales are found to be composed of numerous 

 mites and their debris. The irritation of the mites often causes 

 the birds to pull their own feathers. Birds affected often pull 

 each others' feathers. Some of the so-called feather eating is 

 due to the presence of this parasite, but fowls sometimes pull 

 each others' feathers when the parasite is not present. Salmon 

 says this disease does not affect the general health of the bird 

 and does not appear to disturb gain in flesh or egg production, 

 but Theobald says that the disease checks egg laying in hens 

 and affected cocks become emaciated and sometimes die. 



Etiology . — The mite Sar copies IcEvis which causes this disease 

 is smaller than the one which caiuses scaly leg. They live at the 

 base of the feathers in the epidermal debris referred to above. 

 A flock becomes infected by the introduction of one or more 

 birds carrying the mites. The mites are spread from bird to 

 bird by the male in copulation. The distribution is often very 

 rapid so that the whole flock is soon affected. 



Treatment. — The disease should be prevented by taking care 

 not to introduce infested birds. If it appears all affected birds 

 should at once be isolated. The mites yield easily to treatment. 

 The infested areas may be rubbed with some of the less irri- 

 tating ointments recommended for scaly legs (see p. 141)- 



The following list gives some ointments in the order of their 

 desirability for use on the body. 



Oil of caraway ointment ( i to 5 ) . 



Balsam of Peru. 



Creolin treatment (i to 10). 



Helmerich's ointment. 

 Salmon gives a modification of the latter ointment which he 

 considers an improvement for use in depluming scabies. 



Flowers of sulphur, i dram, 



Carbonate of potash, 20 grains. 



Lard of vaseline, ^ ounce. 

 Scabies may also be cured by liquid applications. The two 

 following preparations are recommended by Salmon : A solu- 



