How often dogs are coming in heat, is varying from dog to dog. In most cases, dogs will come in heat every four to nine months. That is, approximately three, two or a bit fewer times a year.
Of course, there are exceptions possible, like dogs cycling more frequent, or sometimes skipping every now and then. Besides that, there are several dog breeds, like Basenji, who come in heat only once a year.
Most common cycling frequency for female dogs is every six months or twice a year. Many dogs have this like a clock set up and are cycling at exactly predictable rate. Just like some humans do.
Average dog cycling frequency is not written in stone
However, some dogs who do not have so regular cycle (just like some humans do, again). They may come in heat more or less than average. And every time the interestrous period (period between two heats) may be different from previous.
While, there should be no worries having some irregularities in heat cycle, they may also point to health problems underlying. Consider mentioning it to a vet during next regular check up visit. Especially if your dog had regular cycles, and suddenly something happened differently.
Besides most common, twice a year, frequency, it’s not unusual when dogs come in heat three times, or sometimes even four times a year. However, this is already considered abnormality.
In most cases, if the dog comes in heat so frequent, some of the cycles may be infertile. That is, all the symptoms of the heat did occur, but lining of the uterus was not able to become receptive to implantation in such a short time after previous heat.
Also, there are several more abnormalities, like split heat, when female dog starts cycling, but suddenly stops, and begins in several weeks again. There may also be a heat with unapparent symptoms, making owner believe, that dog has not come in heat, yet. In most cases, it is observed with younger dogs. We will take a closes look at abnormal heat cycles later on in our ongoing series about dogs in heat.