Because the estrous cycle shows a large amount of individual variation and since the onset of heat and breeding can be easily overlooked if your cat has free outdoor access, you must keep an unspayed female indoors and isolated from unneutered male cats to prevent pregnancy. Although several companies are working on products to prevent pregnancy in cats and dogs, there are no reliably safe and effective nonsurgical methods available now to prevent pregnancy in cats.
This means that if you choose to live with an unneutered female cat, you must effectively deal with the recurrent behavioral changes that occur during the breeding season if pregnancy is to be prevented. This can be difficult to do, especially if your cat is one of the more vocal and affectionate breeds (e.g., Siamese). Your veterinarian can help you by providing tranquilizers, which may quiet the behavior to some extent, or he or she may be able to artifically induce ovulation, thereby reducing the length of the heat period.
ARTIFICIALLY INDUCED OVULATION
Artifical induction of ovulation is achieved by allowing mating with a vasectomized (sterile) male cat or by stimulation of the vagina with a smooth glass or metal rod or moistened cottontipped swab. A technique using acupressure over the lower spinal area may also work. Such sterile matings produce a state of false pregnancy and can result in a delay of a month or longer before signs of heat occur again.
If you desire, your veterinarian can show you the best way to use a rod, cotton swab, or the acupressure technique for sterile mating or may be able to put you in touch with an owner of a male cat that has had the vasectomy surgery. Unless your cat is a female valuable for breeding purposes, however, these methods are usually more trouble than they are worth. The best way currently available for preventing pregnancy and eliminating heat behavior is the ovariohysterectomy or spaying operation.
OVARIOHYSTERECTOMY OR SPAY
Many misconceptions surround the spaying surgery. One of the most prevalent is that the spay will cause a female to become fat and lazy. Not so. As mentioned earlier, this surgery induces a permanent condition comparable to the anestrous state. Cats become fat only if they are using fewer calories than they are eating. Inactivity (laziness) usually accompanies excess weight. Fatness can be caused by metabolic abnormalities (e.g., low thyroid activity), but this is rare. It is most often caused by overfeeding and is not caused by the ovariohysterectomy.
Another common misconception is that it is important for a cat to have a litter before being altered (spayed), that having a litter is important to “personality development,” or that it “calms a cat down.” In fact, the heat cycle or process of having a litter has no persistent beneficial effect.
Although a female cat often has marked changes of personality during estrus, while pregnant, and when nursing, once the kittens are gone most females return to their usual anestrous personalities.
The best time to perform the ovariohysterectomy is before the first heat.
Most veterinarians recommend not earlier than about four to six months of age. The surgery is easiest to perform while the cat is still young (therefore, easier on the cat) and it is usually least expensive for you at this time. It is uncommon for a cat to come into estrus before six months, but it does occur so be aware of your unneutered female’s behavior in case an earlier heat cycle calls for surgery sooner. Some veterinarians and humane organizations have experimented by performing ovariohysterectomies on kittens less than ten weeks of age. Although this practice has not yet been proven harmful, it does subject incompletely vaccinated and physiologically less mature cats to the stress of a major surgical operation. Pet owners should consider these facts when selecting the age at which to spay their females. If you fail to have the surgery performed before heat or breeding occurs, however, don’t worry that you will have to have an unwanted litter.
Spaying can be easily performed during heat and can also be done during pregnancy, although it will probably be more expensive than if performed earlier. Although there are individual variations, the procedure for an ovariohysterectomy in most good veterinary hospitals is similar to the following: Your veterinarian requests that you withhold food from your cat at least eight to twelve hours preceding surgery.
This allows time for the stomach to empty, preventing vomiting and aspiration of the vomitus into the trachea and lungs during general anesthesia. Preanesthetic drugs are given to reduce apprehension before surgery and to prepare the body for general anesthesia. Anesthesia is usually induced with a short-acting drug given intravenously. Its effects last just long enough to allow the veterinary surgeon to place an endotracheal tube into the cat’s windpipe (trachea).
This airway is the path via which gas anesthetic agents and oxygen are administered to maintain sleep during surgery; it also provides a ready means for resuscitation if any emergency arises.
After the cat is sleeping, the abdomen is clipped free of hair, washed with surgical soap, and disinfected. The cat is then transferred to the surgery area and placed on the operating table belly up. An assistant stands by to monitor anesthesia, breathing, and heart function. The veterinarian, who has been scrubbing his or her hands and donning sterile clothing—cap, mask, and gloves—while the cat is prepared for surgery, steps in and places a sterile drape over the patient before surgery begins.
An incision into the abdomen is made at the midline. The length of the incision varies with the size of the cat and the difficulty of the surgery but is usually not more than an inch long. Most veterinarians use a special hooklike instrument to reach into the abdomen and pick up one horn of the uterus where it lies along the body wall. The uterine horn is brought out through the incision and followed to the ovary. Clamps are applied, and the blood supply to the ovary is interrupted by ligatures (ties placed around blood vessels) or metal vascular clips. The ovary is cut away from its blood supply, which is allowed to return to the abdomen. The other uterine horn and ovary are brought to the incision and treated in the same manner.
Then the uterine horns are followed to their point of attachment to the body of the uterus. Its blood supply is interrupted by ties or clips and the uterine body itself is ligated. An incision is made through the uterus to free it, and the horns and ovaries are removed. (Turn to Anatomy, if you need to review the structure of the uterus and ovaries.) The inner part of the incision is closed with layers of absorbable suture material or stainless steel; then the skin is sutured (stitched) closed. With modern anesthesia, the cat begins to wake up shortly following the last stitches and is ready to go back to an enclosure for final recovery. Most healthy cats are acting and eating normally one or two days following surgery. In fact, most feel so good that it is often a chore to try to restrict their exercise.
When you take your female home following surgery, it’s a good idea to take her temperature and examine the incision daily even if you are not given specific instructions to do so by your veterinarian. (These are good things to do following any surgery.) Fever and/or swelling, redness, or discharge at the incision site should alert you to call your veterinarian for advice. Normal feeding should resume within forty-eight hours following surgery. Many veterinarians allow you to take your cat home before this time; so if you do, provide meals and water frequently, but in small amounts to avoid stomach upset. Vomiting that occurs more than once or twice, especially if accompanied by inactivity, should again prompt you to call the hospital where the surgery was performed for advice.
TUBAL LIGATION, HYSTERECTOMY
Rarely veterinarians and spay clinics perform tubal ligations (tying of the fallopian tubes so the ova cannot pass into the uterus). This involves the same type of abdominal entry as an ovariohysterectomy and, although it is effective in preventing pregnancy, it has definite disadvantages compared to an ovariohysterectomy. It does not prevent pyometra, and it does not prevent signs of heat.
If you are sure you won’t mind living with repeated signs of heat, then you may choose a tubal ligation or, better in terms of health, a hysterectomy (removing the uterus but leaving one or both ovaries). Remember, however, that neither prevents the signs of heat or has a benefial effect against breast cancer. People who choose a hysterectomy or tubal ligation often change their minds a year or two later and request additional surgery to remove the ovaries. Tubal ligation and hysterectomy are not considered standard practice for female neutering in veterinary medicine.