Abortion and premature birth are the most serious accidents that can happen to pregnant mares. Though both terms are often applied indiscriminately, "slipping the foal" is the term generally employed when the young creature is expelled at any time before it is fully developed and the usual time of pregnancy has expired; yet it is recognized by those who make this subject their study that the term "abortion" should imply expulsion of the foetus from the mother when it has not attained sufficient development to live outside its mother's body, while "premature birth" signifies that the young creature has been born before its time, yet with all its organs sufficiently formed to enable it to live for at least some time in the external world. In the first instance it is either dead when expelled from the uterus or it dies immediately afterwards; and in the second it may be weakly and immature and succumb after a variable period, or it may continue to live and eventually thrive. In practice, however, there is no accurately defined limit between abortion and premature birth, and especially when the latter has been brought about by any one of the causes that produce the former.
Abortion is said to take place in mares when the foetus is expelled forty days before the usual period of pregnancy has terminated, and though it may occur at any time during pregnancy, especially before the 300th day, yet it is much more frequent during the first than the second half of pregnancy. When the accident takes place at a very early period it may not produce any appreciable disturbance in the mare's health, and the developing ovum usually escapes intact and often unperceived; but when it occurs at a later stage it is serious, as it not only entails the loss of the foal, but may also compromise the health, or even the life, of the parent.
Many causes operate in bringing about abortion, and some of these have been mentioned; they act more or less in a mechanical manner, and usually only one mare in a number will abort. But when several cases follow each other quickly in a breeding establishment, and no sufficient reason can be assigned for their occurrence, then the question of infection arises, and there can be no doubt now that to this cause must be ascribed the serious outbreaks of abortion among mares in recent years in various parts of Europe, but more especially in the United States of America, where heavy losses have been sustained.
When, therefore, two or three abortions happen in a stud, it is well to adopt precautions at once; indeed, where a number of pregnant mares are kept, such precautions ought to be resorted to when only one accident of this kind transpires, as no one can foretell whether it may not be the starting-point for others.
If it could be arranged for every mare advanced in pregnancy to be kept by herself in a loose-box and paddock, it is very probable that this serious risk might be obviated; at any rate, isolation and other measures could be more readily and effectually applied.
As a preventive of this form of abortion, the surroundings of the pregnant mare should be as clean as possible, and all decaying or putrid animal or vegetable matter ought to be kept away from her. Cleanliness, good food, and pure air and water are the only efficient protectives that can be recommended against abortion, beyond those already mentioned.
When a mare shows signs of impending abortion, if she is not already housed and by herself, the first thing to be done is to remove her to a spacious loose-box, which ought to be kept rather dark, and free from noise. These signs, however, are not very obvious in all cases. Sometimes it happens that the mare appears to be as lively and well as usual up to the moment when the foetus is expelled, while the expulsive act itself is so sudden and quick, and accomplished with so little visible effort or disturbance, that the accident excites very little if any notice. It frequently happens during the night, and surprise is expressed at finding in the morning the aborted foetus, usually contained in its intact envelopes, lying behind an animal which on the previous evening looked perfectly well, and even now is so cheerful and unaltered, and its functions so little impaired, that it can scarcely be believed she has been the subject of such a grave mishap. Even the sentiment of maternity, which is so strongly developed in animals after carrying the young full time, is not awakened in her, and she shows the utmost indifference to the foetus, even treading upon it.
When abortion takes place during the day, the flanks have been observed to fall in a little, the abdomen descends, the vulva and vagina slightly dilate, and there escapes from them a glutinous, reddish-tinged fluid, followed by the foetus. If abortion occurs at an early period in pregnancy, the membranes in which the young creature is enclosed are not ruptured; but when the period is more advanced - it may be towards the seventh or eighth month - these envelopes rupture before expulsion of the foetus, and may be retained in the uterus or ejected soon afterwards.
In other instances, however, especially when pregnancy is well advanced, and particularly if the mare has sustained external injury, there are precursory signs of abortion which the attentive observer may note, but which vary to some extent, according as the foetus is dead or alive. The mare suddenly appears dull and dejected, or is restless, uneasy, and constantly moving about. If the foetus is alive and strong its movements are - by one watching the mare's abdomen - perceived to be frequent, violent, and disordered, but they soon become feeble and infrequent, and cease altogether when it has died. The mare shows symptoms of illness, and these are soon succeeded by those that characterize ordinary parturition, and spontaneous birth of the dead progeny takes place, or, in rare instances, it may be necessary to remove it manually.
SHIRE MARE AND FOAL, WYKEHAM MABEL.
By English Oak 2771; dam. Wykcham Whitefoot by Samson II. The Property of the late .Sir J. B. Maple. Bart.
In other instances, when the foetus is not removed from the mare spontaneously or artificially after it has ceased to move in the uterus, the mare regains her ordinary tranquillity, appetite, and liveliness, and all the symptoms disappear for one or more days, when they are again manifested, and the foetus may be expelled without any apparent effort, or after much straining.
When it is observed that abortion is likely to occur, it is advisable to obtain professional advice as soon as possible. If the accident has already occurred, however, then, if other pregnant mares arc near, they must be at once removed to a safe distance from the place, which should be cleaned and disinfected as soon as possible. Everything in the way of litter and remains of fodder, together with the foetus and its envelopes, ought to be burned, and the ground well scraped and disinfected. The hind-quarters of the mare should also be washed with carbolic water, Condy's fluid, or solution of corrosive sublimate (1 per 1000); one of these fluids, warm, should also be injected into the uterus if this is emptied of its contents. Until all this has been done, and some days have elapsed, the mare must not be allowed to associate with in-foal mares. It is also advisable to prohibit persons who have attended on the mare approaching these until they have at least been disinfected.
It is a wise measure to keep pregnant mares away from horses affected with infectious or contagious diseases, such as influenza and strangles, as, if they become affected, they may abort, or the maladies may be transmitted to the progeny.