Do dogs have periods? Understanding your dog's seasons

Have you ever wondered whether dogs have periods?

While unspayed female dogs do pass blood from their vulva at times, they don’t menstruate like humans. This bleeding is part of their reproductive cycle – commonly known as being ‘in season’ – which is often misunderstood. 

Understanding seasons in dogs will help you to give your pet the care and comfort they need during this time.

Whether you’re a first-time dog owner or just want to better understand your female dog’s behaviour, this guide covers everything you need to know about dogs in season and how to support your pet through their heat cycles.

The amount of time your dog is in heat can vary, but most cycles will last between two and four weeks. Your dog will usually bleed for between seven and 10 days during this time, though this can vary.

While heat cycles last roughly the same amount of time from breed to breed, every dog is different. One dog’s cycle might be a week longer than another’s, even if they’re a similar breed and size.

Age is another factor. As dogs get older, you might find that their seasons are further apart and each season can last longer. While older dogs are unlikely to become pregnant, they don’t go through a menopause like humans.

The oestrus cycle is a natural reproductive process that unspayed female dogs experience throughout their lives. Unlike human menstruation, dogs in heat don’t shed their uterine lining monthly.

Instead, oestrus in dogs involves several distinct phases that prepare the body for potential pregnancy. However, bear in mind that unspayed female dogs are more at risk from health conditions such as pyometra.

Proestrus is the stage when bleeding is observed and lasts approximately nine days. During this phase, your dog’s body prepares for potential mating.

You’ll initially notice bloody discharge from the vulva, which becomes swollen, with the discharge becoming clearer or straw-coloured as proestrus progresses. Female dogs aren’t typically receptive to mating during proestrus.

This is the fertile phase of your dog’s heat cycle, when the egg is released, and they are receptive to mating. Oestrus typically lasts between four and nine days, but it can range anywhere from three to 21 days. 

You might notice that the bloody discharge becomes lighter in colour, and the vulva stays swollen.

Dioestrus is the period following oestrus and the release of the egg, if the dog isn’t pregnant. This stage lasts for approximately 60 days.

Although there are few external symptoms, sometimes unpregnant female dogs show signs of a false or pseudopregnancy whereby they can build nests, carry toys around as if they are puppies, and even produce milk.

False pregnancies exist so unpregnant dogs in the pack could wet-nurse another dog’s puppies. False pregnancies typically last for around two weeks and usually pass without treatment. They will likely recur the next season and they are another common reason why it is important to consider spaying your female dog.

Anoestrus occurs after dioestrus and lasts three to four months. During this time, your dog’s reproductive system rests, and hormone levels return to normal. Typically, there are no visible signs during this portion of the cycle.

Most dogs will come into heat about twice a year, or once every six and eight months, but this can vary due to several factors.

Smaller breeds can cycle three or four times a year, while some larger breeds might only go into heat once a year – or less frequently.

Similarly, as dogs age, their cycles can become more irregular or occur less frequently.

If you’re concerned that your dog’s seasons are irregular, it’s a good idea to speak to your vet.

A dog’s first season typically happens between 6 and 12 months of age, but this can vary by size and breed of dog. Smaller breeds tend to mature faster, while large breeds might start later. Some may wait until they’re over 12 months old to have their first season.

Spaying your puppy is recommended to avoid unwanted seasons and potential pregnancy. If you’re considering getting your dog spayed, speak to your vet to figure out the best time for them to have the procedure.

Dogs in season don’t typically experience too much pain, though some may feel mild discomfort similar to menstrual cramps in humans. Most discomfort comes from hormonal changes, causing restlessness or behavioural changes, rather than actual physical pain.

Recognising dog in heat symptoms helps you prepare for this natural process and ensure your pet stays comfortable and safe.

• A swollen vulva that appears larger than normal
• Bloody discharge that may range from bright red to dark brown
• Increased urination, often used to mark territory and attract males

• Restlessness or a change in sleeping habits
• Nesting (digging, circling, gathering blankets)
• Increased affection
• Mounting behaviour, presenting to other dogs and increased interest in mating
• Increased roaming
• Loss of appetite
• Increased attention from male dogs in the area
• Licking their back end more frequently
  
  

If your dog is in heat, you can help them by prioritising their comfort and safety. Spend time with them and keep them entertained to help manage any discomfort or anxiety they may be experiencing. Sticking to a usual routine can help, too.

Keep them away from unneutered males, especially when out on a walk, ensuring they’re always kept on a lead. Be aware that your dog will be motivated to seek males while in oestrus and therefore normally well-behaved dogs can ‘ disappear’ on walks.

It’s also worth keeping an eye on their behaviour and taking notes to help you recognise patterns and prepare for heat cycles in the future. 

Exercise and socialisation tips for safetyMost dogs will lick themselves clean while in heat, but some owners purchase washable dog diapers or specially designed pants to protect furniture and carpets when their dog is in heat. 

Place washable blankets on favourite resting spots and consider encouraging your dog to stay in easily cleaned areas. 

Regular bathing with gentle dog shampoo can help manage odour and discharge, too.

You can still walk your dog while they’re in heat – but be vigilant. Always keep them on a lead and watch out for unneutered male dogs who will likely show an interest in them.

To be safe, you might want to skip busy dog parks and opt for shorter, more frequent walks instead.

The only way to permanently stop heat cycles is through spaying, or neutering, a surgical procedure that removes the ovaries and usually the uterus. This prevents future heat cycles and eliminates unwanted pregnancy risk.

Spaying can also provide some important health benefits, including a possible reduced risk of mammary cancer. 

Your vet can give you guidance on when to get your dog spayed. Most vets avoid spaying dogs when they’re in heat, so it’s best to spay them between cycles, as this can make surgery easier and safer.

If you have dog insurance with Petplan, you can also access our Pet Expert Chat by logging into your My Petplan account and speaking with someone about your dog’s heat cycle or reproductive health.