Abnormal and unusual heat cycles in female dogs

As a general rule, a fertile unsprayed bitch will come into heat around twice a year, but not every bitch will have normal heat cycles, or come into heat just when you expect them to! There are a range of different heat cycles and abnormal patterns of coming into heat that bitches can experience, and it is a good idea to learn about them so that you can tell if there is anything unusual about your own bitch’s heat cycle.

If you own a good quality pedigree bitch that you wish to breed from, you will have to get to know her heat cycles fairly well in order to know when she is fertile, so that you can mate her with a dog when she will receptive to this and also, be sure to keep her away from male dogs when you don’t want her to breed!

Additionally, if you have a puppy or adult female dog that you are planning to neuter, you will generally have to wait for the first heat cycle and so, the onset of sexual maturity to do this. For older dogs that have not been neutered when younger, you will also need to know when she is likely to come into heat so that she is not spayed at this time.

Spaying a dog in heat is more challenging and risky and so, best avoided, and so your vet will likely ask you to ensure that you schedule neutering between heat cycles, and not when the bitch is in heat or about to come into heat.

In this article, we will look at some of the different abnormal and unusual heat cycles that may present in bitches, and how they affect their ability to breed, and your own ability to monitor their cycles. Read on to learn more.

Silent heat

A so-called “silent heat” is what happens when your bitch does come into heat within the expected or regular timeframe, but with few or no symptoms of heat, meaning that dog owners may often miss the fact that the bitch is in heat at all and think that they have missed a heat cycle.

This can cause problems because you will not know when the bitch is fertile for breeding, and so you might miss the window of opportunity if you have planned to breed and have a stud dog on standby, but also because the bitch may mate and conceive during this time because you won’t be vigilant about contact with male dogs, leading to potentially unwanted litters.

In some cases, signs of heat will be present but very subtle, and if you know your bitch is due for a heat cycle, you may be able to spot the signs if you are vigilant. However, the only way to know for sure if your bitch has had a silent heat or missed going in to heat altogether is to ask your vet to monitor their hormone levels.

Absent heat

An absent heat is of course what happens when your bitch skips going into heat when they are due to in their normal heat cycle. In young bitches under the age of two or even older for some large and giant breeds that are slow to mature, like the mastiff, absent heats are not unusual, and it can take a couple of years for a bitch’s heat cycles to stabilise and become regular.

However, in adult bitches who are fully mature, absent heat can be caused by a huge range of factors including poor nutrition or physical condition, stress, and certain health conditions that affect the glands and hormones such as hypothyroidism.

You might never know for sure why a bitch misses a heat cycle-these things do happen from time to time. However, if a bitch over the age of two misses a heat cycle, it is not generally a big deal, but you might want to ask your vet to examine them and check for any potential health problems that can cause the problem.

Split heat

Split heat is one of the more confusing variants of abnormal heat cycles in dogs, and a bitch is said to be suffering from split heat if she appears to come into heat as normal at the normal time, showing all of the usual indications such as receptiveness to breeding, bleeding, and a swollen vulva-but she does not actually reach the fertile stage and come into oestrus, and so goes back out of heat.

She will then come into heat again-anywhere between ten days to ten weeks later-and again, display all of the markers of being in heat but this time, usually with the accompanying oestrus and ability to conceive that she missed during the first stage of the split heat.

Split heat is most common in young bitches, and occurs because they are not yet mature enough to support the full hormone production that causes a full and fertile heat cycle. Most bitches will only have one or maybe two split heats-if they have any at all-and after that, will have matured enough to have a normal heat cycle.

However, if your dog is older or has had more than one split heat cycle, you might want to talk to your vet about running some tests.

Abnormal heat cycle intervals

Sexually mature adult bitches come into heat around twice a year or so, but this can be very variable. Some bitches may come into heat as often as every four months and others as long as eight or nine (or even longer), but once a bitch is mature, however long her heat cycles are, they should fall into a fairly predictable pattern.

Smaller dogs tend to have shorter heat cycle intervals, whilst larger dogs usually have longer ones-but as long as the intervals are not highly erratic, this is not a problem. However, intervals of more than 12-18 months between heat cycles should be checked out by your vet, as should very erratic heat cycle intervals with a lot of variance.

Overly short or long heat cycles

How long a bitch remains in heat for can be fairly variable too, but the average is around three weeks or 21 days. If your bitch’s heat cycle only lasts for a few days or goes on for over a month, assuming that they are sexually mature, this may be indicative of a problem that again, your vet should check out.