Do Female Dogs Experience Menopause? By Jocelynn Jacobs, DVM Dr. Jacobs is a veterinarian, breeder, and exhibitor of Alaskan Malamutes. She has a breederreferral practice where she works with breeders and performance dogs owners. One question I get asked often as a breeder-veterinarian is what will happen to my bitch when she gets older – will she go into menopause like people do? It is an interesting question that deserves to be explored. The health of our bitches after their reproductive years are over is important. Should they be spayed? Will they eventually stop cycling? Do their chances of developing a pyometra increase as they age? The Aging Ovaries As your female dog enters her senior years and continues to have heat cycles, her ovaries may start to physically look abnormal. Normal ovaries are about the size and consistence of a soybean in small dogs and a lima bean in large dogs. Over the years, they can develop pitting along their surface or may develop small cysts filled with fluid. During spays on older females, I have seen some ovaries look like a small piece of cauliflower with cysts and thickened tissue covering them. They continue to regulate hormonal releases, but they lose the accuracy to do it as well as when they were young. The interval between heats may increase as your dog gets older, decreasing the number of times they go into heat each year. In one report, 18 month old dogs cycled an average of 1.65 times per year, while 7 year old bitches cycled an average of 1.4 times per year.1 As your bitch continues to age past 7, fewer and fewer heat cycles occur. Eventually, they may stop cycling all together. In this regard, it is similar to human menopause, but in dogs there are other considerations – mainly dealing with uterine health. The Aging Uterus The ovaries and uterus communicate back and forth so they know what is happening reproductively. The ovaries tell the uterine lining when to be ready for ovulation and go into estrus. The uterus tells the ovaries when it is pregnant. Hormones are their means of communication. The lining of the dog’s uterus is called the endometrium, and it remains proliferative (thickened) throughout its life. Many other species do not have proliferative uterine linings all their lives – this may be one reason dogs are unique when it comes to their reproductive tract as it ages. As your bitch gets older, communication between the ovaries and uterus may not be as efficient as when they were younger. The proliferative lining of the uterus may undergo degenerative changes or excessive thickening because the communication between the two organs begins to fail. As the condition progresses, inflammatory cells appear trying to rid the uterus of excessive mucous or thickened tissue. Then the uterus fills with high numbers of inflammatory cells and may even develop a secondary bacterial infection. This is pyometra, a pus filled uterus, which can be a deadly condition if not treated by your veterinarian immediately. So as your bitch ages, even though they may not cycle as often as they did in their younger years, the ovaries and uterus continue a not-so-effective form of communicate which eventually can cause pyometra. Therefore, to prevent this from happening, all female dogs should be spayed when they are no longer being used in a breeding program. Is There a Magical Age? Before a bitch of any age is bred, their overall health should be considered. In all instances, they should in perfect health, but this is especially important when considering breeding a bitch over 6 years old. These dogs should have a thorough examination by your veterinarian. Blood work and a urinalysis should be considered to screen for potential metabolic conditions or organ disease. The physically demanding needs of pregnancy or hard labor could exacerbate pre-existing disease conditions, threatening your bitch’s life. As bitches age, their fertility drops - their conception rates decrease and their litter size usually also decreases. In one study, bitches between 3 and 5 years of age had the best conception rates and largest number of surviving puppies.1 So, if your bitch is in excellent health, how old is too old for them to be bred? When a survey was taken of breeders of small, medium and large breeds of dogs, and they were ask what age they usually stop using their bitches in a breeding program, most said 7 or 8 years age.2 Some breeders mentioned considering the total number of litters the bitches has as well – the more litters, the early they should be taken out of a breeding program. I recommend to my clients bitches be spayed by 7 or 8 years of age (or younger if the bitch is no longer being bred), to eliminate the risk of pyometra. Bitches are the foundation of our breeding program, and their overall and reproductive health are critical to its success. Ensuring their health continues beyond their reproductive life and into their golden years should be just as important as when they were younger. Sidebar Reproductive Problems Seen As The Bitch Ages Increased time between heat cycles Increased puppy losses Decreased conception rates Decreased litter size Development of cystic endometrial hyperplasia (thickening) Development of ovarian cysts and cancer Development of uterine cancer Development of vaginal cancer References: 1. A. Anderson. Reproduction. In Anderson AC, ed. The Beagle as an Experimental Dog. Ames, IA, Iowa State University Press, 1970a, p. 31. 2. J. Cain and A. Davidson, “The Reproductive System and Prostate Gland.” In Goldston and Hoskins, eds. Geriatrics and Gerontology of the Dog and Cat. W.B. Saunders,1995, pgs 347-348.
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