Annual Report for 1911 of Roijal Veterinary College. 349 



The foregoing figures attest the marked reduction in the 

 prevalence of glanders in this country during the last seven 

 years, and more particularly during the last four. Since the 

 actual eradication of pleuro-pneumonia and rabies this reduction 

 constitutes the most striking success which has been achieved 

 by means of the Diseases of Animals Acts, and it is therefore 

 interesting to examine how the improved state of things has 

 been brought about. 



During the thirty years preceding, 1904 the number of 

 outbreaks reported annually varied considerably, but in no year 

 did they fall so low as 500, and from 1887 to 1903 they averaged 

 over 1,100 and never fell below 700. Throughout the whole 

 of this period, and indeed down to the end of 1907, the only 

 method of diagnosing glanders which was taken into account 

 in dealing with the disease under the Glanders Order was what 

 is conveniently termed clinical diagnosis. By this is meant that 

 a case was not diagnosed as one of glanders unless the horse 

 exhibited the well-known external lesions of glanders or farcy. 

 The law, therefore, took no cognisance of the fact that in 

 glanders, as in other bacterial diseases, there is a period of 

 incubation, during which the animal shows no abnormal 

 symptoms whatever, although the germs of the disease are 

 multiplying in some part of the body. 



It ought to be said, however, that although the earlier 

 Glanders Orders made no provision for counteracting the 

 danger involved in the movement of horses affected with 

 glanders in its incubative stage, this was not so much 

 because the danger in question was not suspected, as because 

 at that time veterinary science knew no method by which 

 glanders could be recognised before the development of out- 

 ward symptoms. In the early nineties of last centiiry mallein 

 was discovered and brought into use, and the experience thus 

 gained in this and other countries almost revolutionised the 

 views which had previously been generally held regarding 

 what may be termed the normal course of glanders in the 

 horse. Formerly it had been generally believed that the latent 

 or incubative period of the disease was almost always short, that 

 when a horse became infected outward signs of the disease were 

 soon developed, and, furthermore, that in the great majority of 

 cases glanders soon terminated fatally if the disease was 

 allowed to run its natural course. In many outbreaks when 

 the mallein test was applied to all the inmates of the stable, 

 an alarming number of the apparently healthy animals reacted, 

 and growing experience derived from post-mortem examina- 

 tion of such reacting horses soon showed that the reaction to 

 mallein could be accepted as proof of the existence of disease, 

 the animal's healthy appearance notwithstanding. 



