Female pitbull dog

Most female dogs will go into heat twice a year.

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How long does a female dog’s season last?

By Dr Holly Graham BVMedSci BVMBVS MRCVS Veterinarian

Updated on the

How long does a season last? Many first time dog owners may be concerned by their dog’s heat cycle, as this isn’t something that only lasts for a couple of days!

Seasons begin once a bitch reaches sexual maturity, often at around 6 months - but some dogs may start later than this. If a female dog isn’t neutered, these seasons will continue for the majority of her life; but these seasons can become irregular and cause health problems.

Most female dogs will go into heat, or oestrus every 6 months, averaging twice a year. The age at which this begins depends on the breed - and on the individual. Unless you are planning on breeding your dog, neutering (or spaying in females) is a good idea to prevent health problems and stop unwanted pregnancies.

When does the oestrus cycle begin?

Most dogs begin having seasons at around 6 months of age, but this can happen as early as 4 months! Larger or giant breeds may take longer to mature, and can start as late as 12-18 months of age. First seasons can be a stressful time for both dogs and owners, but are a normal part of sexual maturity.

Breeding early in a dog’s life, either on the first or second season, isn’t advised. Dogs at this age haven’t matured fully and breeding a young dog could be dangerous for her and her puppies. If you aren’t planning on breeding your dog, most vets strongly recommend neutering. This prevents messy seasons, unwanted pregnancies and associated health problems. Your vet will be happy to advise on the best time to neuter your dog, based on their size and health.

When can a dog get pregnant?

How long is a dog in season?

The length of a dog's season is usually between 2-4 weeks. Early in the cycle, female dogs are not receptive to male dogs. Ovulation generally occurs in the middle of the cycle, but dogs don’t read the rulebook and this can be earlier or later. Some dogs may throw the book out completely and can be receptive throughout the whole cycle. During her season, you may notice male dogs are significantly more interested in greeting your dog - but take care if you aren’t interested in mating her!

Bleeding can be very mild, or more noticeable. Lots of dogs clean themselves well and owners may not notice any blood spots, whereas others may need a nappy!

Stages of the heat cycle

There are four stages of the heat cycle observed in dogs:

Proestrus: in this stage, the vulva begins to swell and there is bloody discharge. Males are attracted to females, but females shouldn’t allow them to mate. You may notice behavioural changes, like increased clinginess or neediness. This stage lasts anything from 4-20 days.

Oestrus: when ovulation occurs and when mating can take place. You may notice a swelling of your dogs vulva, or a change in vaginal discharge from bloody to watery or yellow. Females will willingly accept a male during this phase, in fact, they may even seek them out! A way to reliably know whether a female is ready to mate is to run your hand down her back and over her rump. Dogs who are in heat move their tail to one side when you do this (an instinctual behaviour known as ‘flagging’, done so that the tail doesn’t impede entry by a male). Mating occurs during this phase. Length of 5-13 days.

Diestrus: this is the name given to the period of time that passes after mating. It is during this stage that pregnancy occurs, if the mating was successful. Unsuccessful or no matings may result in false pregnancies or uterine infections during this period. This period lasts for much longer, around 60-90 days.

Anoestrus: this last stage is mainly a period of inactivity between oestrus phases and lasts 2-3 months.

Does this process occur for the rest of a dog’s life?

Once oestrus cycles have begun, they continue for most of your dog’s life. These cycles can be regular, and happen every 6 months or they can be irregular and unpredictable. Some unfortunate dogs may have seasons more frequently, and can become distressed by this - or there can be a longer period between seasons. Owners should be aware of when their dog’s last season was, to help identify problems, or choose the correct time for neutering.

Unspayed females can get pregnant at any age, although the chances of this reduce as your dog reaches a more senior state. Unwanted health problems such as pyometras become more common as your pet ages, and conditions like mammary tumours can be associated with not neutering your dog.

Many dog owners choose to spay their dog before their first heat, and there is evidence to suggest this reduces the chances of developing mammary cancer later in life. Studies suggest earlier neutering greatly reduces mammary cancer risks. Modern medicine has given us lots of information regarding the best time to spay. The best time for your dog will depend on size, breed and maturity. Your vet will be able to offer advice on what is best for you and your pet. Most vets recommend neutering 3 months after a dog’s season, when the tissues are inactive to make the procedure as safe as possible. As well as the traditional spay method, some clinics now offer laparoscopic spays, which may suit your pet better!

Precautions when dealing with a dog in heat

Dogs should not be bred on their first heat. Dogs at this young age are physically and emotionally immature, and there are risks for both the mother and the pups. Heat can be a stressful time for your dog, and you may notice behavioural changes. Female dogs can be more challenging to take for relaxing walks during this time - lots of unneutered males will be showing interest, and it can be difficult to fend them off! Some females may attempt to find themselves a mate, so care must be taken to prevent them from escaping and coming to harm.

It’s important to keep an eye on your dog’s health if she isn’t neutered. Complications like uterine infections, or pyometras are common and can be fatal. Problems tend to occur 1-2 months following a season, so it’s necessary to keep checks on when your dog was last on heat.

Final considerations

Preparing for your dog’s season and considering neutering can be a daunting prospect. Fortunately seasons usually only happen a couple of times a year, and neutering is an easy process if you aren’t planning on breeding your dog. If you choose not to neuter your female, you must be aware of complications that can be fatal - such as uterine infections like pyometra. Speak to your vet to help make an educated decision about what is best for you and your dog.

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