K) June, IS16.] Contaijious Abortion. 325 



same position. By contamination of pastures in the same way, the 

 organism may pass through the alimentary canal, and this method j» 

 probaVjly the chief one in the spread in a herd of pregnant cows. 



An abortion occurring on a farm is regarded by the farmer in far too 

 light a manner — not until a number have occurred does he realize the 

 gravity of the situation. I have previously said that until proved other- 

 wise every abortion should be regarded as of the contagious variety. 

 This applies more particularly to the first case which occurs in a herd. 

 As a rule, the farmer is content to say it is just a case of " slipping." 

 If it should happen to be the contagious form of the disease the evil 

 effects spread considerably, and when a number are affected the farmer 

 becomes worried. Tlie time to worry is at the first sign of trouble, nor 

 wait until the disease has gained a firm footing. Strict isolation of the 

 first case to occur on a farm, until it is proved to be' non-contagious, will 

 be a splendid insurance against the remainder becoming affected, or, at 

 any rate, it will assist considerably in keeping an outbreak within reason- 

 able limits. 



Symptoms. 



Cows are most likely to abort in the fifth or seventh month of preg- 

 nancy, though it may occur both earlier and later, there is a tendency 

 for a cow that lias once aborted to carry the calf for a longer period at 

 subsequent gestations, if she becomes pregnant. Abortion is usually 

 preceded by slight swelling of the genital passages, and an odourless 

 discharge of reddish grey or yellowish colour occurs. At times it mav 

 be blood stained. If the cow is milking, the secretion becomes dimin shed, 

 and the character of the milk changes to somewhat like colostrum or first 

 milk. Within a few days the abortion takes j^lace. If it is early in the 

 period of gestation the membranes come away with the foetus, if later 

 in the period, the membranes may remain attached for some time. 



Following the abortion there is a continuous vaginal discharge of 

 dirty brown or reddish material with sometimes fetid odour. This 

 gradually diminishes, and may cease completely, and tliere is nothiuf?: 

 to show the animal is affected except an inability to get her in calf again. 

 The earlier after abortion that pregnancy can be obtained, the more 

 certain is a subsequent abortion, whilst the longer interval that occurs 

 the more likely is normal birth to occur. 



D1AGX0.SIS. 

 Tiie infectious character of the abortion is indicated by the pre- 

 monitory signs which usually appear two or three days before aborting, 

 and by the continuous discharge after; in this discharge the organism 

 may he found on microscopical examination. Laboratory methods 01 

 diagnosis have been tried, but up to the ))resent no finality l>^s bet-n 

 reached . 



COURSK. 



The disease persists in a herd for years, after the fust ca.se there id 

 a period of calm followed by almrtions in rapid sucres-sioii mitil normal 

 ])irths are exceptional. This continues until two or tliree al)orti<Mis per 

 animal have occurre<l, when an immunity is apparfiilly estihiish-ft 

 and only newly introduced cows are affect<>d. The course of the disease in 

 Victoria appears to vary somewhat to that in CJreat Britain, for lure. 



