The ovaries are not unfrequently the seat of structural or functional diseases which, although not seriously affecting the general health of the mare, may, and sometimes do, render her vicious and useless. When these morbid states exist, the temperament and habits of the animal undergo a marked change, and what was before a quiet unaggressive mare now becomes a restless, unseemly, and dangerous creature.
During the period of oestrum, or what is commonly spoken of as "horsing", there is at all times a certain degree of exceptional irritability, and this is evident in some mares more than in others. But in the cases referred to above, it sometimes becomes so pronounced as to require the greatest care in their handling and general management. As the aestral period expires the danger may pass away, but in some mares it continues throughout the summer, while in others aestrum becomes a chronic condition. These animals are more or less constantly "horsing", and receive service after service without any result. The morbid sensibility they display renders them dangerous not only to drive, but likewise to attend upon in the stable.
When they are touched or even approached they squeal, straddle, let themselves down behind and throw out a quantity of urine, and the labia are spasmodically opened and closed for a number of times. Sometimes they will strike out with their fore-limbs, and the danger of such an animal is her tendency to kick and injure those about her. Mares so affected are difficult to put in and take out of harness, and they frequently lean towards one side or the other and refuse to be straightened. Sometimes they may be driven without fear, and at other's they become vicious and kick furiously at the vehicle to which they are yoked.
Habits of this kind are not unlikely to be attended with serious consequences, and the owner naturally seeks for something to be done to correct them. Here the operation of ovariotomy, or removal of the ovaries, is the only remedy by which the animal can be rendered quiet and useful. Sometimes, especially in the case of old mares in whom the vice of kicking has become indelibly established, the operation does not seem to overcome it altogether, but as a rule the contrary is the case, and the mare is rendered quite quiet and useful for all kinds of work.
It is seldom that animals of this kind will breed, and nothing is lost therefore by removing the organs of reproduction.
It is advisable that some attention should be given to the condition of the mare before the operation is commenced, and especially in respect to her diet. For three or four days previously she should be fed on sloppy bran, and during the last twenty-four hours before the operation, all food should be withheld and very little water allowed; this should be given early on the morning of the operation.
Inasmuch as the rectum is immediately above the part to be operated upon and the bladder below it, it is necessary that both these organs should be emptied of their contents. By so doing, additional room is acquired for the operator, and if an enema or two be thrown up the former before the operation, the liability of soiling the hands is thereby guarded against.
All the outlying parts of the mare, as the under surface of the tail, the rectum, the perineum, and the labia, should be thoroughly washed with warm water and soap, and after being sponged with clean water should then be freely dressed with a 5 - per-cent solution of carbolic acid. This should be done in the morning, and again immediately before operating.
As the vagina is the part to be operated upon, it becomes of the first importance to ensure that it, as well as the part leading to it, should be rendered as thoroughly aseptic as possible. For two or three days before the operation an antiseptic solution of chinosol, or perchloride of mercury, or carbolic acid should be injected into it morning and evening; and when the mare is cast, and while under the influence of chloroform, this can be repeated, and in addition the walls of the vagina should be thoroughly sponged with antiseptic solution.
The instruments required for the operation are an ecraseur (fig. 523), a knife whose blade is guarded (fig. 526), and an enema syringe. These must be thoroughly cleansed and boiled, or placed in a 5-per-cent solution of carbolic acid for two or three days before being used. The sponges or wool, or whatever is used for mopping up the blood, must be similarly dealt with.
Having sterilized the instruments, the operator must give strict attention to his own person. Dirty hands or a dirty garment may make the difference between success and failure. He should wear a gown which has been washed and rinsed in a solution of carbolic acid or perchloride of mercury. His hands and arms should be washed and brushed in soap and carbolized water, and afterwards rinsed in a fresh solution of the same.
The nails must be cut short and be thoroughly cleansed. These preliminaries having been completed, the operation may be proceeded with.
In casting a mare for the purpose in question, the ordinary hobbles (Plate LI) will suffice, after which she may be brought under the influence of chloroform in the ordinary way.
There are two positions in which an animal may be placed for being operated upon: - (1) Standing. (2) Recumbent.
In the former the parts to be dealt with are in their natural position, and are in this respect more readily seized and removed; but to restrain these animals for such an ordeal requires the administration of large doses of morphia or chloral, and even then a good deal of unnecessary pain and struggling invariably results.
The most convenient and humane method is no doubt to place the animal in the recumbent posture, and, as we have suggested, to put her under the influence of chloroform.
In this condition all sense of feeling is obliterated or put to rest. There is no pain nor suffering, and the mare may be put in any position the operator may require.
When this has been done, the operation may be proceeded with. This consists in making a hole in the walls of the vagina, through which the hand may be passed into the belly.
The operator, placing himself in a recumbent position behind the mare, takes the guarded knife (fig. 526) in the left hand and carries it into the vagina. At the anterior extremity of this cavity will be felt a short, fleshy projection, the neck of the uterus. This may be used as a guide for the incision which must be made in order to reach the ovary. The knife is carried to the inferior part of this body (as the animal lies), and being then unsheathed, is carefully plunged through the walls of the vagina. Having done this, the fingers one after another are then passed into the opening, which they enlarge by tearing the structures until the hand can be introduced. The tearing is done in order to avoid haemorrhage, which would follow incision of the vessels of the part.
Fig. 526. - Guarded Knife. The dotted line shows the blade pressed forward for cutting.
On entering the abdomen the hand is passed in an upward and forward direction, following the line of the horn of the uterus, and the ovary will be found suspended from the spine behind the kidney. In a natural condition the ovary is somewhat soft, but in these nymphomaniacs it usually becomes more or less hard, and may be either enlarged or contracted.
Fig. 527. - Cystic Ovary.
A, The ovary entire. AA, Cysts distended with fluid. B, Ovary in section, aa, Cysts or Cavities from which fluid has been removed.
The next stage in the operation is the removal of the gland, and for this purpose the ecraseur is passed through the wound made in the vagina. The chain of the instrument is then placed round the parts which suspend it, and tightened up by turning the screw slowly until the ovary drops into the hand. Care must be taken to secure it, and not allow it to fall into the belly. The other ovary is then removed in a similar manner.
This having been done, the operation is completed and the mare is allowed to rise. Usually these cases make a good recovery, and, excepting slight temporary uneasiness and colicky pains occasionally for the first few hours, no unfavourable symptoms are presented.
The mare should be kept on scalded food for a day or two, and gradually returned to her normal rations.
If after removal the ovaries be examined, they will be found to be in one of two conditions. Either they are much smaller than is natural, or they are irregularly enlarged. In the former case they are hard and contracted in consequence of having undergone a process of fibroid degeneration, or in other words they have been converted into fibrous tissue. In the latter, when divided with the knife, a number of cavities of different sizes are found, filled with watery fluid. In this case the ovary is in a cystic condition (fig. 527). Many of these cysts are Graafian follicles which have become inordinately large, and in some instances by mutual pressure have broken into each other.