In short, no, male dogs do not have periods while female dogs do have periods but not in the same way that human females do. Most mammals, dogs and humans alike, share the same basic reproductive organs but the ways those organs function is not similar. Women go through a menstrual cycle, a process of preparation for egg fertilization that lasts an average of 28 days. Female dogs go through an estrous cycle which lasts an average of 180 days.
In humans, the uterus builds up nutrients for the anticipated growth of a foetus. When an egg goes unfertilized, that substance is secreted from the body. In dogs, when an egg is unfertilized, that nutrient-rich material is absorbed by the body over an extended period of time. The bloody discharge that emerges from female dogs originates in the vagina, not the uterus, and serves a different function. Rather than marking the conclusion of a cycle, in dogs, it signals the onset of fertility.
While dogs technically do not menstruate, going through the estrous cycle primes them for mating and signals that they are ready.
It basically comprises of four phases:
1. Proestrus
Dog’s vagina discharges blood and other fluids during the first two of these phases, most heavily during proestrus. When we say a female dog is in heat, this constitutes the first two phases, proestrus and estrus. During proestrus, which can last from three to 17 days, a female dog’s body produces large amounts of estrogen. In dogs, this is accompanied by the start of bloody vaginal discharge, which is dark red to begin with, and caused in part by excessive hormone and pheromone production. Dogs also urinate much more frequently during proestrus. The hormones and pheromones in the blood and urine attract potential mates over large distances.
2. Estrus
Estrus is the shortest part of the estrous cycle, lasting from four to seven days. This is typically when a dog is primed for mating and fertilization. During estrus, bleeding tends to continue, though it may slow and take on a lighter tint. Discharge in estrus can range from a lighter shade of red to pink to coloured. In this phase, a dog may sleep more, be less inclined to play, and begin building a nest in anticipation of pregnancy.
3. Diestrus
At the start of the third phase, diestrus, the bloody discharge ceases, whether the dog’s egg has been fertilized or not. Diestrus lasts approximately 65 days, about the same span of time that marks a dog’s pregnancy. If the egg is not fertilized, diestrus is the phase during which the nutrients that have accumulated to nourish the anticipated litter of puppies are reabsorbed by the body.
4. Anestrus
The final phase of a dog’s estrous cycle is anestrus, and for this two-to-three month span, the dog is sexually and hormonally inactive.
Just like humans, the period where dogs get their period varies. On average, female dogs will go on heat at 6 months. This varies based on size and breed.
The appearance of your dog’s “period” changes as the cycle progresses. It starts of bloody and thick and gradually changes to a more watery, with slight tinges of blood. At the same time, the vulva may become red and swollen.
The number of times that your dog will “bleed” in a year varies in different breeds. Smaller dogs tend to have more cycles will larger dogs may only have one cycle a year. An interesting fact – dogs do not get menopause and are able to breed even in their senior years.
Research has shown that dogs do not show pain or discomfort when on heat but there may be some emotional changes that you may notice during this period. Some may become needier while others may become more aggressive. Remember to always be there for your dog regardless and provide them with love and support based on her needs!