Diagnosis. Veterinary Police. 937 



such variations the disease may last for years in horses, dogs 

 and swine. 



Diagnosis. While scab simulates eczema in regard to the 

 tissue changes which occur, its recognition is possible by its 

 localization on certain parts of the body, by the obstinate itch- 

 ing wdiicli increases wdth warmth, and especially if its occur- 

 rence and spread point to an infectious origin. Nevertheless 

 the diagnosis is completely assured only by demonstration of 

 scab mites in the diseased parts of the skin. Examination for 

 mites should not be neglected in doubtful cases, for instance if 

 the complaint is only beginning to develop or has spread over 

 a great portion of the body, so that its starting point can hardlj- 

 be determined; the exact determination of the variety of mite 

 is generally possible only by this procedure. 



The simplest way of demonstrating the mites consists in detaching crusts 

 from the diseased skin, especially their deeper parts or still better scrape away the 

 debris of the part of the skin which is covered with crusts and spread it out on a 

 glass plate, watchglass or piece of paper, and afterwards warm it; this may most 

 suitably be done by exposing it to the sun's rays. The warmth causes the mites to 

 move about, and they may be seen on a dark background as small moving points. 

 With the point of a needle they may be put on a glass slide and examined under 

 the microscope. This procedure is suitable for the investigation of dermatocoptes 

 and dermatophagus mites. It is more advantageous to take off the crusts from the 

 skin and put the scrapings in 10% potassium hydrate for 1 to 2 hours, afterwards ex- 

 amining them between glass slide and cover glass, when in the softened and partly 

 dissolved material the uninjured remaining mites or parts of their bodies will be 

 easily recognized under the microscope (characteristics of scab mites see pages 932 

 to 934). Sarcoptic scab may be diagnosed also by placing the scabs on a man's 

 arm (in 6 to 12 hours itching occurs and pustules form containing minute mites). 



Veterinary Police. The frequent enzootic occurrence of 

 scab and the considerable losses entailed thereby justify its in- 

 clusion in the notifiable diseases. The rules and regulations 

 generally affect solipeds only (horse, ass, mule) and sheep. 

 In solipeds, veterinary police regulations are necessary only 

 with regard to sarcoptic and dermatodectic scab, while they do 

 not appear to be needed against the rather harmless dermato- 

 pliagic scab. A similar view ought to be taken with regard to 

 dermatocoptic and sarcoptic scab of sheep, although sarcoptic 

 scab is not included under the animal orders of the German 

 Empire. The scab of goats ought also to be included in the 

 veterinary police regulations. On the contrary on account of 

 the very slight transmissibility of sarcoptic scab and the non- 

 transmissibility of other forms of scab to other species of ani- 

 mals the extension of the orders for restriction of trade in re- 

 gard to other species of animals does not seem warranted. The 

 regulations concern themselves on the one hand with the com- 

 pulsory veterinary treatment of scabs and on the other with 

 the isolation of affected animals. In the treatment of the horse 

 where the disease is widespread it must not be forgotten that 

 the cost of treatment may exceed the value of the horse, in which 

 case slaughter of the animal will be justified. The skins of 



