Abnormal heat cycles in female dogs

We all love to plan ahead and trust that everything is predictable. Mother Nature likes that too; however, she’s not always able to deliver. While most dogs go into heat twice a year and stay in heat for 21 days, abnormalities do occur.

This article gives a brief summary about possible abnormalities in the heat cycle of female dogs. Sometimes a cause can be innocent, such as a dog coming into heat due to immaturity.

However, the heat cycle can often be disrupted by serious health issues. Therefore, veterinary attention should be sought if one of the following occur.

Silhouette of woman and a female dog

Absent heat

As the name implies, absent heat is when a dog does not come into heat, even though it should. It can occur in young dogs who have not yet come into their first heat after the age of two or in mature dogs who had cycled regularly before but suddenly stopped cycling.

Reproductive system diseases are the most common cause of absent heat, and the dog should be examined by a veterinarian. 

Absent heat can also be caused by medicine used for treating other conditions, especially if the medicine involves hormonal therapy. Talk to your veterinarian, but in most cases, the heat cycle should eventually return to normal if the treatment is applied properly.

Poor general health in a dog can also trigger a skipped heat cycle in order to conserve energy.

Absent heat is often confused with the dog not being fully mature yet and so-called silent heat, which is described next.

Silent heat

Silent heat happens when the dog is in heat, is receptive, can get pregnant, but does not show heat signs. Sometimes males are not attracted to dogs in silent heat, but they often are.

In most cases, signs are actually present but are so weak that dog owners miss them. These are the lucky ones because many people struggle with their dog’s behavior changes during heat.

It’s not uncommon for smaller dog breeds to have one or two silent heats before clear symptoms appear.

Silent heat should not be confused with the owner’s inexperience at noticing symptoms, as bloody discharge and the swelling of the vulva may easily go unnoticed or get mistaken for something else.

If a dog is in silent heat, the only way to confirm the heat cycle  is to take the dog to the vet who will perform vaginal secretion and blood tests.

Split heat

Split heat is when the heat cycle begins, but then stops before the second phase, standing heat, begins. It commonly occurs in young dogs during their first heat because the hormonal systems are unable to induce ovulation. In the case of young dogs, there should be no worries, and normal heat cycle is likely to reoccur within two to ten weeks.

On the other hand, split heat in a mature dog should be examined by a veterinarian.

Prolonged heat

Dogs are normally in heat for 21 days. Anything longer than that is considered to be a prolonged heat.

This is a relatively frequent occurrence, and there is nothing to be concerned about in younger bitches. However, if prolonged heat occurs when the dog has reached maturity (2-3 years), a veterinary examination is necessary.

Most often mature dogs stay in heat for too long because of an ovarian cyst or tumor. While it sounds unfortunate, when diagnosed early, the reproductive organs usually can be surgically removed with no fiurther health hazard.

Too frequent cycling

Most dogs come into heat twice a year, but it is common for dogs to cycle three or four times per year.

There should be no worries if this happens in young dogs; their cycling frequency must stabilize as they mature. However, if your dog cycled regularly before, but suddenly started coming into heat more often, she must be seen by a veterinarian.

Note that if you are into breeding, some of those “extra” heats may be infertile since the dog’s body needs proper time to recover from the previous cycle.

Too rare cycling

While dogs normally come into heat twice a year (except some specific breeds who go into heat once a year), it is still normal if a dog does not come into heat up to a year or a year and a half, especially for young or old dogs.

Everything longer than a year requires medical examination, especially if your dog has had a regular heat cycle before. Unfortunately, there are too many possible causes to make speculations on a website, and you must visit a veterinarian.

This article is a part of series about female dogs in heat.