Livestock Ailments.

Putaruru Press, Volume VI, Issue 251, 23 August 1928, Page 6

Livestock Ailments.

THEIR TREATMENT. (J. Lyons, M.R.C.V.S., Director of the Live Stock Division, in the Journal of Agriculture). (Continued). No. 111. Contagious Abortion. This is a specific disease caused by a bacillus which sets up a catarrhal condition of the lining of the uterus recognised by the expulsion of the foetus at any time during the period of gestation. The principal source oi infection is through the alimentary tract and blood-stream, or the organism may gain entrance through the vagina per medium of the ' bull or through the female’s hindquarters coming in contact with infectious material. When the infection reaches the uterus slow catarrhal inflammation is set up, which gradually separates the placenta or cleansing from its attachments. As the process proceeds the foetus is gradually deprived of nourishment and is ultimately expelled as a foreign body. This may occur at almost any period during gestation, but most commonly takes place between the fifth and seventh months. The disease can be spread to certain other animals by inoculation, but is seen to the greatest extent among dairy cows. The ravages of the disease are felt throughout New Zealand, and in this respect we do not

stand alone, as its effects are widespread in every other civilised country where dairying is carried on. A feature of the disease is the extreme virulence shown when it first appears in a clean herd—any number up to 50 per cent may abort. In each succeeding season the number of cases diminishes, until ultimately few are experienced, provided the farmer has been breeding his own stock and no fresh animals have been introduced. This is due to the fact that owing to the presence of the infection jn the system a certain amount of immunity has been conferred. This is the stage at which the majority of our herds in New Zealand have arrived, as proved by the fact that the number of cases seen in any given herd is nothing like so great as was the case fifteen to twenty years ago. There are still exceptions, and the disease is still liable to be seen in a virulent form where the germ gains a footing in a clean herd.

In a pastoral country such as ours, where the herds range on pasture all the year round, the risk of infection and difficulty of control are greater than where the animals are housed for a considerable part of the year. In the latter case the cows are for the most part calved indoors, and the discharge after calving can be controlled and dealt with, thereby saving the pastures from contamination. It must be remembered that once a cow has aborted she remains a carrier of the disease more or less for the re- I mainder of her existence, and, al- ' though she may carry her calf for the full time at each succeeding calv-

ing, being still a carrier she is spreading infection during each calving period. It will thus be seen that the matter of preventing the spread of fresh infection is a somewhat difficult one —in fact, it is almost impossible unless the owner is prepared to subject a‘ll animals in the herd to the agglution test, separate the infected animals from the non-infected, and run the herd in two different sections. Even then it would be necessary to see that the non-infected cows were placed on paddocks free from infection, and that hay or ensilage from land on which affected cows had been grazed before the material had been cut was not fed to the clean herd. Owing to the difficulties of segregation most owners prefer to take the risk of a few cows slipping each year. At the same time every effort should he made to lessen the risk of infection and as far as possible keep it within bounds.

Symptoms.—There are no . general constitutional symptoms in abortion | disease, the general health of the i animal remaining unimpaired | throughout. If the animal is under ■ observation preparatory symptoms I will be seen, in some cases a few j weeks but more frequently only for a few days, before the act takes place. Those seen in approaching parturition consist of swelling of the vulva, slackening of the pelvic ligaments on each side of the tail, and tension of the udder and teats. If the animal is in milk, curds and even blood may be noticed in the secretion, giving it the appearance of colostrum or beastings. In cases where the udder is not in active secretion milk can be observed in the gland. There is also a discharge of yellow gelantinous maI terial from the vulva, and later uneasiness or slight straining may occur. If abortion takes place in the - early period of gestation these symp-

toms are absent, the foetus being expelled in its membranes; and the first indication of what has taken place consists in the animal showing signs of returning to the bull.

When an animal aborts the afterbirth is retained usually for a few days, but in a few instances it may remain for weeks until it comes away in shreds. If the afterbirth is seen, at those parts where it has been attached to the womb a thick gelatinous, purulent material will be observed, and the same material is also attached to the womb. This exudes as a yellow purulent material which later turns to a brownish watery discharge. This discharge is highly infectious, and every effort should be made to see that it is not spread all over the farm by infected animals and thus become a source of further infection. Prevention and treatment consist l in isolation. As soon as an animal shows signs, of abortion she should be placed in a paddock reserved for this purpose and kept by herself. After the act the foetus should be burned or buried, and any membranes which come away should be treated similarly and not allowed to lie for dogs to carry about the premises. For the first few days the womb should be irrigated daily with a mild antiseptic solution, or pessaries may be used, after which, and before the animal is allowed to run with the rest of the herd, irrigation should be done at intervals until the discharge disappears. Such an animal should not be put to the bull for at least two and a-half to three months after the date of abortion. All aborted cows in the herd should be treated similarly, and the paddocks should afterwards be grazed with sheep or with dry cattle intended for fattening. If these measures are strictly observed it will go a long way toward preventing the spread of further infection.

It must also be remembered that when the womb is inactive the abortion bacilli migrate to the udder and are secreted with the milk. This when fed to calves, although it does not affect them permanently, passes through their digestive tract and may be a source of infection to other pregnant animals.

As a means of controlling the disease vaccines—both live and dead cultures—have been tried, but so far without affording relief. Experience in this respect shows that dead cultures are incapable of promoting either preventive or curative action, while although living cultures may confer some immunity their use is prohibited by the fact that they are absolutely dangerous, inasmuch as they may be an active agent in introducing the disease. Investigation and research into abortion disease has so far not given us a practical means of control, and in the light of our present experience we have still to depend on preventive measures. (To be Continued).