Spaying a Female Dog or Cat: The Basic Facts Pet Owners Need to Know

Is your female dog or cat spayed?

Spaying is one of the routinely recommended procedures for female dogs and cats. However, many pet owners are confused about the terminology that is used as well as why the procedure is considered important for female pets.

Spaying – Definitions and Terminology

Spaying, in today’s common vernacular, refers to altering a female pet. Spaying involves removing all or part of the reproductive tract of the dog or cat. When a cat or dog is spayed, she is no longer able to become pregnant.

The reproductive tract of both the dog and cat is located inside of the abdominal cavity. A pair of ovaries are located near the kidneys, one on the right side and one on the left side of the abdomen. Each ovary is surrounded by oviduct which carries the eggs produced in the ovary to the uterus. The uterus is connected to the ovaries via the oviduct and consists of two horns, one on the right and one on the left, that come together in a V shape and become the cervix of uterus. The cervix separates the uterus from the vagina, which passes through the pelvic canal to an external genital opening called the vulva.

The term ovariohysterectomy (OHE) refers to the removal of both ovaries and the majority of the uterine tract. The term ovariectomy (OE) refers to the removal of both ovaries while the uterine tract is left in place. Pet owners should consult with their veterinarian prior to the surgery to find out which procedure will be performed for their pet. Traditionally, in the United States, OHE was routinely performed. However, recently, there has been a trend toward performing OE instead.

Both the ovariohysterectomy and the ovariectomy can be performed via traditional surgical techniques involving a surgical incision, either on the lower abdomen or in the flank area and removal of the appropriate organs. However, endoscopic surgical techniques are becoming more widely available and may offer advantages over traditional surgical approaches in the form of smaller surgical incisions, shorter recovery times and less pain. Both procedures require general anesthesia for the pet.

Benefits of Spaying A Cat or Dog

Spaying your dog or cat has numerous benefits.

• Dogs and cats that have been spayed do not come into heat. Female dogs experiencing their estrous period (their heat cycle) bleed from the vulva and attract male dogs. Female cats in heat vocalize loudly and frequently and are quite annoying to have in your home. They also will attract male cats.
• Spayed female dogs and cats cannot become pregnant, so there is no danger of unwanted puppies or kittens and no danger of whelping or queening complications which could endanger your pet’s life.
• The reproductive tract is no longer present in the spayed female so uterine infections (also known as pyometritis or pyometra) cannot occur in spayed female dogs and cats. This is one of the arguments for performing an ovariohysterectomy which removes most of the uterus as opposed to the uterus remaining in the dog with an ovariectomy.
• Dogs and cats that are spayed before their first heat or estrous cycle have a very low rate of mammary cancer development later in life. After the first heat cycle, the incidence of mammary cancer increases a bit and continues to increase with each heat cycle experienced by the pet. After roughly the fourth or fifth heat cycle the benefit of spaying in regards to a decreased incidence of mammary tumors is no longer present. However, the other health benefits remain.

Risks of Spaying Your Female Dog or Cat

The risks of spaying are primarily those involved with the surgery and anesthetic. Much like when a person is anesthetized, there is always a minimal amount of risk. Check with your veterinarian prior to surgery to find out what precautions are taken to prevent anesthetic complications. Your dog or cat should be monitored closely before, during and after the surgery. Blood pressure, heart rate, respiratory rate, temperature, EKG, pulse oximetry (a measure of the oxygen saturation of the blood) and end-tidal CO2 (a measure of the amount of carbon dioxide being exhaled) should all be monitored routinely by your veterinarian and his/her staff while your pet is anesthetized.

Potential surgical complications include infection and excessive hemorrhage during or after the surgical procedure. Surgery should take place under sterile conditions. Pain medication should be provided during the surgical procedure itself and afterward. Administering pain medications prior to surgery can help eliminate wind-up pain (an increase in the susceptibility to pain that makes existing pain harder to manage). In other words, preventing pain from occurring generally is more effective than trying to treat existing pain. Pain medications should be continued at home as well and may be needed for several days post-operatively. Make sure you follow your veterinarian’s advice in administering these medications.

A study released in December, 2009 by Dr. David Waters and his colleagues at Perdue Research Park cites a correlation between longevity and the presence of ovaries in Rottweiler dogs. This study would seem to indicate that spaying a female dog may shorten her lifespan. However, though the results of the study are interesting, the study design has some faults that make accurate interpretation of the data obtained from the study difficult. Hopefully, this is an area where further research will take place. However, at the current time, it is my opinion that this one study does not provide enough concrete evidence to override the known health benefits of spaying. In fact, at this point, I think the study has raised more questions than it has answered.

There is also a paper which was published in March, 2007 by Laura Sanborn entitled The Long Term Health Effects of Spay/Neuter in Dogs. In this paper, the author reviews much of the published research literature pertaining to the spaying of female dogs. The paper is her interpretation of the data presented in the literature. Unfortunately, her conclusions are not shared by all. There is not space here to review each individual piece of literature. Suffice it to say that the paper raises some interesting points and certainly indicates that further research is needed. However, I, like many of my colleagues, do not consider the paper to be strong support that spaying should not be performed on dogs or that the procedure is unhealthy for most dogs. I would encourage pet owners interested in this article to obtain copies of the research literature that is presented in this paper and read the literature themselves before accepting the claims made in the paper. In my opinion, this paper ignores or seriously downplays many of the problems which are associated with intact animals, especially female dogs. For instance, the incidence of mammary tumors in intact females is far higher than the incidence of osteosarcomas in my experience. Spaying at an early age can almost completely remove the chance of mammary tumor development.

When Should A Dog or Cat Be Spayed

Ideally, the spaying of your dog or cat should occur prior to the first heat cycle. Consult your veterinarian to determine the most appropriate age for your pet. At my hospital, we routinely spay dogs and cats at 4 months of age or older. However, some hospitals spay at a much earlier age, sometimes as young as 8-10 weeks or younger, particularly in shelter or pound situations where the animals are often placed in homes shortly after 8-10 weeks of age. Other veterinarians prefer to wait until the pet is closer to 6 months of age.

Some hospitals prefer not to spay dogs or cats while they are in heat. When an animal is in heat, the blood vessels that support the uterus and ovaries are enlarged and are more likely to bleed if not ligated securely. It is for this reason that there is a bit more risk involved with spaying a dog or cat which is heat. At my hospital, we try to postpone the surgery for animals which are in heat until the heat cycle has been completed. However, when cats are involved the heat cycle is erratic and it is often necessary to spay female cats that are in heat. Other hospitals routinely spay both cats and dogs that are in heat. Check with your veterinarian to find out what he/she recommends for your pet.

Animals can be spayed while they are pregnant and often this is the best way to eliminate a litter of unwanted puppies or kittens. However, the risks involved with spaying a pregnant animals are higher than with an animal which is not pregnant. If an accidental mating has occurred and spaying is to be performed, it is best to perform the surgery early in the pregnancy rather than later. It is worth mentioning also that some pet owners have strong feelings about spaying a pregnant dog or cat. If there is a possibility that your dog or cat has become pregnant and you do not want any puppies or kittens aborted during the course of the spay procedure, you should discuss your options with your veterinarian prior to surgery.

Spaying a Female Dog or Cat

Spaying is recommended for all dogs and cats which are not being used for breeding purposes. It is advisable to have your cat or dog spayed prior to her first heat cycle as there are health benefits to doing so. Discuss with your veterinarian the proper age for spaying and any other questions you have regarding your pet’s spay procedure.

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