104 



Imes (M.). Cattle Scab and Methods of Control and Eradication. — 



U.S. Deft. Agric, Washington, D.C., Farmers^ Bull. no. 1017, 

 December 1918, 29 p., 15 figs. [Received 10th April 1919.J 



The parasitic mites causing scabies in cattle belong to the genera 

 Psoroptes, Sarcoptes, Chorioptes and Demodex. 



Psoroptes communis bovis, the cause of common cattle scab has been 

 previously dealt with [see this Review, Ser. B, vi, p. 14]. 



Sarcoptic scabies due to Sarcoptes scabiei bovis seems to be increasing 

 east of the Missouri river as well as in the south-western States. It 

 sometimes develops in pure bred cattle and these may carry it without 

 any visible signs of infection at time of shipment. The effects of 

 this disease are more severe than those of common scabies, and it 

 is more difficult to eradicate ; if not properly treated the infection 

 may last for years, causing great losses. In dairy herds it may also 

 affect the milk. The parasite is described ; the life-cycle is spent 

 entirely on the body of the host. These mites penetrate the upper 

 layer of the skin and form galleries in which oviposition takes place. 

 The egg-laying period probably lasts 12-15 days, each female laying 

 10-25 eggs. The eggs hatch in 3-10 days, the nymphs after several 

 moults reaching maturity in about 10-12 days. Sarcoptic scabies is 

 transmitted by direct contact, and is contagious to man as well as 

 other animals. In moist protected places away from its host the 

 mite may live 3 weeks or longer, but when exposed to the sun, it dies 

 in a few days. Lime-sulphur or nicotine dip is useful as a treatment, 

 and if used should be repeated about 4 times at intervals of 6-10 

 days. Dipping in crude petroleum usually kills the eggs as well as 

 the mites, but is sometimes injurious to the animals. 



Symbiotic scabies (tail mange) is caused by Chorioptes bovis bovis ; 

 it is less serious than the two mentioned above, and although contagious 

 to all classes of cattle, it cannot be transmitted from o;ie species of 

 animal to another. Treatment is the same as for common scab. 



Demodex follicular um bovis is responsible for demodectic or follicular 

 mange which occurs in dogs, horses, man and other animals as well 

 as cattle. It is practically incurable, but its progress may be delayed 

 by regular dipping. Should it reach an advanced stage the affected 

 animals should be killed and the rest of the herd dipped as a 

 precautionary measure. 



This paper also gives full directions for dipping and spraying cases 

 of scabies. Lime-sulphur dip should be used at a temperature of 

 95°-105° F. ; to make it, 12 lb. of unslaked lime or 16 lb. of commercial 

 hydrated lime should be formed into a thin paste with water, and 24 lb. 

 of flowers of sulphur should be sifted into the paste and mixed well 

 to the consistency of mortar with the addition of water. The mixture 

 should then be added to 30 gallons of boiling water, taking care not 

 to interrupt the boil which should continue for l|-2 hours until a 

 dark amber colour is reached. The constituents must not be allowed 

 to settle to the bottom whilst boiling, but when cooling the liquid 

 should be allowed to stand until all solids have settled, leaving it clear. 

 For use this should be diluted with warm water to make a total of 100 

 gals, of dip. 



Nicotine dips, to be efficacious, should be used at a strength of 

 ^Q of 1 per cent, nicotine ; if used stronger they are injurious to 



