DemodectiG 

 MANGE 

 in Cattle 





Photomicrograph of Demodex folliculorum bovis. 



Demodectic mange in cattle is caused by a cigar- 

 shaped, sluggish mite 1 about one-fiftieth inch long. 

 It lives in the hair follicles of an animal's skin and 

 causes lesions, or nodules, that appear as deep pits or 

 holes in the tanned hide. Each year, this damage costs 

 U. S. cattle owners an estimated $5,000,000. 



Although demodectic mange is an old disease found 

 in every class of livestock and in man, we know little 

 about its transmission, treatment, control, or life his- 

 tory. The disease has not been transmitted by artificial 

 or experimental means. The possibility of prenatal in- 

 fection has been suggested but not proved. In dogs, 

 the organism has been found internally. 



Appearance of Lesions 



Demodectic mange in cattle causes nodules usually 

 in the neck, shoulders, and brisket. They range from 

 the size of a match head to that of a hazelnut. They 

 are caused by the formation of pus that accompanies 

 the mite. A single nodule may contain 20,000 or more 

 mites. All stages of development, from eggs to adults, 

 occur in one nodule. 



Except in advanced cases there are no marked 

 changes in the animal's hair coat, and ordinarily you 

 cannot see the lesions until you part the hair. You can 

 feel the nodules by passing your hand over the ani- 

 mal's body with your fingers pressed firmly against 

 the skin. 



Demodectic mange may spread quickly, and the 

 nodules may appear nearly everywhere in the animal's 

 skin. It may spread slowly, and the number and size 

 of the nodules may show little change for several years. 



Demodex folliculorum bovis. 



The nodules usually are firm. In advanced cases 

 several may unite to form a small abscess. If such an 

 abscess breaks and discharges its contents over the 

 surrounding hair and skin, the condition looks like 

 common scab. 



Diagnosis 



If you think one of your cows has demodectic 

 mange, have your veterinarian examine it. 



The nodules contain a creamy white material of 

 cheesy consistency. Usually the veterinarian will lance 

 the nodule to obtain this material for examination. 

 He can find the mite easily by pressing the contents of 

 one or more nodules between two glass slides and ex- 

 amining it under a low-power microscope. 



Control 



Although demodectic mange does not spread rapidly 

 to other members of the herd, you should isolate ani- 

 mals infested by the mites. 



Demodectic mange in cattle does not respond to any 

 treatment we know. The usual cattle scab dips and 

 sprays appear to slow progress of the disease. If the 

 nodules are small, they will cause no perceptible in- 

 jury and you may ignore them. 



Sometimes bacterial infection causes open demodex 

 nodules to abscess. You may treat such abscesses with 

 local antiseptics if they continue to discharge. Use 

 light pressure to squeeze out accumulated pus and 

 flush it away with warm, soapy water. Then, gently 

 swab the abscess as deeply as you can; apply tincture 

 of iodine with a small piece of sterile absorbent cotton 

 tightly wrapped around the end of a toothpick. 



