By Dr. Marley, Bellbrae Animal Hospital
The reproductive system of dogs and cats are much different from humans, and are different from each other. By understanding these differences and how it affects the health and behaviour of our pets, we can gain a better understanding of why spaying and neutering helps avoid the distress, inconvenience and expense of several health concerns.
Puberty typically occurs in dogs at 9-10 months. Dogs, unlike humans, undergo estrus rather than menstruation. Estrus typically occurs every 6-8 months and lasts for an average of 9 days, but can range from 3-21 days. Females continue to cycle as they age – they do not undergo menopause – but the length and duration of the cycles become more irregular. During estrus (or “heat”), a female will be receptive to breeding, and will often go to great lengths to be bred. Dog owners will often state that a dog that has previously never tried to escape a fenced yard will suddenly do so once they have they the motivation! This applies to both intact females and males, and males can catch the scent of a female in heat from surprising distances. Because of the tendency of both males and females to travel to find mates, there is a much higher risk of injury from car accidents than their neutered friends. Because breeding of unspayed females is often accidental, this lead to the challenge of not knowing when and if a female was bred, and therefore when her pups are due. Furthermore if the paternity is unknown, we can have concerns about whelping if the female is a smaller breed. As a result, we are often faced with the decision of proper timing for performing a caesarean section.
As females ages, the risk of pyometra increases. Pyometra refers to an infection in the uterus and can be sub-classified into open or closed pyometra depending on the state of the cervix. In open pyometra, an abnormal vaginal discharge may be noticed by the owners. In closed pyometra there is no discharge; this condition is even more life-threatening and can lead to sepsis and death. Treatment in both cases is ovariohysterectomy (spay surgery), however the risk of surgery is greatly increased because of the compromised health of the pet. There is also a higher rate of mammary tumours in intact females as they age, which also require surgery. For male dogs, prostatic enlargement and infection have a higher rate of occurrence in intact males. This can lead to pain and difficulty urinating, and occasionally difficulty defecating.
Cats also undergo estrus, however estrus occurs in response to lengthening daylight hours. In addition, they are induced ovulators, meaning they will continuously come into heat until they are bred. Females (called queens) can be extremely vocal at this time and can be difficult to live with. Like dogs, a female in heat will attract intact males from some distance and owners will often find tom cats yowling and spraying urine outside their home (usually at night). Tom cat urine smells extremely strong and is even more unpleasant if the tom is kept indoors. Queens generally produce two or even three litters of kittens every season, which means one queen can produce over a hundred kittens in her lifetime. We continue to struggle with an overpopulation of cats for this reason.
Intact cats when outside also roam more widely than their neutered co-parts and are at increased risk of injury from fighting with other cats, which can cause cat bite abscesses and increase the risk of contracting viruses like Feline Immunodeficiency Virus (FIV) and Feline Leukemia Virus (FeLV).
Like dogs, cats are susceptible to both pyometra and mammary tumours as they age. In cats mammary tumours are metastatic approximately 90% of the time.
Our primary goal as responsible pet owners is to keep our animals healthy and safe through the course of their lives. We can easily avoid a number of health concerns by simply having our pets spayed and neutered when they are young and healthy. They are both routine procedures and the recovery time is short compared to the same in an older pet. We can increase the safety of the procedure by checking blood work prior to surgery and delivering intravenous fluids during the procdure. If you have any questions about spaying or neutering your pet, the best person to ask is your veterinarian!