A woman generally undergoes menopause during her late 40s or early 50s. After menopause, women are no longer fertile and egg production ceases. Dogs share many physiological similarities to humans, including a decline in fertility. While female dogs technically do not undergo menopause because their heat periods do not always stop completely, they reach a menopause-like state that shares signs and symptoms with human menopause.
Female dogs maintain regular heat periods during their younger years. As they age, however, dogs experience a significant decline in heat periods. Smaller dogs reach this senior phase of reproduction at around eight or nine years of age. Large dogs begin their sexual decline sooner, at around six years of age.
Irregular Heat Periods
The hallmark sign of a female dog entering her menopause-like phase is a sharp decline in number of heat periods per year. Most young dogs experience two heat periods per year. Older dogs that have reached a menopause-like state experience shorter heat periods or never go into heat at all. This irregularity of heat cycles signals a dog's entrance into a menopause-like stage.
As a female dog enters its adult years and heat periods become more irregular, its uterus changes. If a dog has had multiple heat cycles and not become pregnant, the lining of the uterus thickens and hardens. This may cause inflammation and bacterial infections, according to Purina.
Despite the tapering off or total cessation of heat cycles, female dogs may still be fertile. Fertility decreases significantly and the chance of a dog become pregnant is lower. However, heat periods may resume abruptly, causing the dog to potentially get pregnant.