ANIMAL DISEASES. I37 



for foals that had developed the disease. Altogether about 600 

 foals were thus treated, but full details of the results have not 

 yet been collected from the veterinary surgeons and owners. 

 it may be said, howev^er, that many of those who have used the 

 vaccine for mares before foaling and for healthy foals at birth 

 have expressed themselves as highly satisfied owing to the small 

 number of cases of joint-ill that subsequently occurred, or to 

 complete freedom from the disease after the vaccination. 



Unfortunately, from the outset of the investigation it has 

 been found very difficult to assess the value of any method of 

 treatment, because there has not been discoverable anywhere 

 information to show what is the average incidence of joint-ill 

 among foals in this or in other countries, and until the previous 

 reports of the Institute were published there was also very httle 

 information to indicate what is the average mortality among 

 foals attacked with the disease and left untreated or treated by 

 different methods. The figures which the Institute have collected 

 suggest that the mortality among foals affected with the disease 

 is somewhere about 50%, and it is feared that the vaccine treat- 

 ment practised this year has not lowered that figure. This year 

 an attempt has been made to ascertain both from veterinary 

 surgeons and owners actual figures showing for a number of suc- 

 cessive seasons : (i) the number of foals bom, (2) the number of 

 those that developed joint trouble, and (3) the number of the 

 latter that died from the disease. 



Contagious Abortion in Mares. — This disease has been under 

 investigation at the Institute since igi6. In the spring of that 

 year, the occurrence of a number of cases of abortion in a stud 

 was reported to the Institute, and an investigation, which was 

 made immediately, led to the isolation of an organism which 

 appeared to be the cause of the trouble, and which was subse- 

 quently identified with a bacillus isolated in cases of abortion of 

 mares in Holland and the United States. Later work proved 

 that this bacillus was actually responsible for the disease, and a 

 serum was accordingly prepared for the treatment of pregnant 

 mares known to have been recently exposed to infection. The 

 Institute is now in a position to decide immediately by bacterio- 

 logical examinaton of the aborted foetus, or by testing the 

 blood of the mare, whether any case of abortion is caused by 

 this bacillus or not, and by applying the latter test to the other 

 mares it is also possible to ascertain to what extent the disease 

 has spread in the stud. With this knowledge it is often possible 

 to effect an immediate separation between the diseased and the 

 healthy, and thus cut short the outbreak. 



