How Often Do Dogs Come in Heat

Kelly Roper
Two Collies

How often do dogs come in heat? That's a question with more than one answer.

About the Heat Cycle

The onset of heat cycles usually begins when most bitches reach the age of six months, although larger breed dogs may not have that first cycle until closer to a year old. Even so, veterinarians aren't concerned when those cycles begin unless a bitch reaches beyond two years old without ever having had an obvious cycle. At that point, it may be worth letting a vet examine her to determine why she doesn't cycle and whether that might be detrimental to her health depending on the cause.

During the cycle, the bitch goes through physical changes that result in vulvular swelling, blood-tinged discharge and the release of eggs for fertilization, otherwise known as ovulation. This cycle runs approximately three weeks on average, although this can vary quite a bit.

So, How Often Do Dogs Come in Heat?

The following info represents the most typical cycling patterns of most bitches, with the exception of incomplete cycles.

Every Six Months

Typically commencing between six and ten months of age, many bitches will continue to cycle every six months for the majority of their lives. Cycles might be delayed a bit following a pregnancy, but most bitches will resume cycling about four to six months after delivery once the they are fully recovered from raising their litters.

Once a Year

A good number of bitches will only cycle once a year, and this can happen regardless of whether they began cycling at six months or one year old. As a general rule of thumb though, many bitches that begin cycling at one year of age will continue to cycle once a year thereafter.

Every Four Months

It's more rare, but some bitches fall into a pattern of cycling every four months or roughly four times a year. However, at least one of these cycles is usually infertile. This means that ovulation does not occur even if the bitch gives signs of being willing to breed.

Incomplete Cycles

In even rarer cases, some bitches will begin a cycle only to have it end prematurely. They often resume cycling within a month or two. This irregular heat cycle pattern is sometimes referred to as a "split cycle," and it's not completely unusual for a young bitch to experience this irregularity during her first cycle or two until she establishes a regular pattern.

Heat Cycles in Senior Dogs

It's a fact that bitches do not go through menopause like women do, so they have the potential to have heat cycles throughout their entire lives. However, the cycles may grow farther apart as factors like aging and health problems come into play.

When It's Time to Worry about Irregular Cycles

If a bitch that has previously had a well-established pattern of heat cycles suddenly misses a cycle or two, it's a good precaution to make your vet aware of the situation. Sometimes a physical malady can affect how often a bitch comes into heat, and it's always better to consult your vet sooner rather than later. Sometimes simple stress or a nutritional deficiency can delay the heat cycle, and that situation is often easily resolved. In other cases, it may even become necessary to spay the bitch in order to ensure her health. Let your vet be your guide.


As you can see, the answer really varies when it comes to the question of how often do dogs come in heat. One way to get an idea of how often you can expect your dog to cycle is to find out how often her own mother cycled. This trait often runs the same within family lines, although there are always exceptions.

How Often Do Dogs Come in Heat