A dog is usually in heat for about two to three weeks, that is around 18-21 days from the first signs until it is all over. That is the average, however, and there is a big difference from dog to dog. Some female dogs are quickly through it in a couple of weeks, while others draw it out for almost a month. The actual period during which your dog can become pregnant is shorter and typically lies in the middle of the cycle. For the vast majority of female dogs, the heat repeats about twice a year, that is roughly six months apart, but both duration and frequency depend on breed, age and the individual dog's nature.
How long your dog is actually in heat is best gauged by keeping an eye on the physical signs and behavioural changes along the way. Below we go through the phases day by day, when your dog is fertile, what you can expect of her mood and appetite, and how you best support her with calm, routines and good meals during a period when her body is busy.
How long does the heat last, and what happens in each phase?
The heat is typically divided into phases, and it is the sum of them that adds up to the two to three weeks. It begins with the bleeding phase, which is called proestrus. Here the vaginal opening swells, and you see a bloody, quite heavy discharge. This phase often lasts about nine days, but can vary from a few days to a week and a half. During proestrus your dog attracts male dogs, but she still rejects them and is rarely willing to mate yet.
This is followed by the fertile phase, estrus, when your dog is receptive to mating. The discharge often changes colour from bright red to more pink or straw-coloured, and she stands still and moves her tail aside if a male dog approaches. Estrus too typically lasts about nine to ten days, and this is when she can become pregnant. So if you want to avoid puppies, it is throughout this entire period that you must keep her on a lead and under supervision, because the time window is often wider than many people expect.
Finally the signs subside, and the body enters the hormonal resting phase after the heat. The visible symptoms gradually disappear over the course of about a week, after which your dog is back in her usual rhythm until the next time. If you are unsure exactly when your dog is fertile, or you are planning a litter, your vet can follow the cycle more closely, for example by measuring hormones.
How often does the heat come, and when does it begin?
Most female dogs have their first heat somewhere between six and twelve months of age, but it varies greatly with the breed. Small dogs are often early and may start as early as around six months, while large and heavy breeds may wait until they are a year and a half or older before the first heat arrives. The first time is often a little irregular, both in length and in intensity, and that is completely normal.
After that the heat typically comes twice a year at roughly six-month intervals, but some breeds only have one heat a year, and a few have three. The rhythm usually becomes more predictable once your dog has grown up. A female dog does not stop coming into heat the way humans go through menopause. The intervals may become longer and the cycle milder over the years, but an older dog can still come into heat, and it is worth keeping an eye on this with your senior dog.
If you notice sudden changes in the rhythm, very heavy or prolonged bleeding, or discharge outside of the actual heat, it is a good idea to contact your vet so that together you can have it assessed whether everything is as it should be.
Which signs and behavioural changes should you look out for?
The most tangible signs are the physical ones. The vaginal opening becomes swollen, and there is a bloody discharge, which many people notice because the dog licks herself more down there or leaves small spots. Some female dogs clean themselves so thoroughly that the bleeding is almost invisible, so pay attention if she starts licking herself markedly more than usual. Many female dogs also urinate more frequently during the first few days, because they are, so to speak, leaving calling cards for the male dogs in the surroundings.
The behaviour often changes just as clearly as the body. Your dog may become more clingy and affectionate, or on the contrary more restless, distracted and hard to get to listen on the walk. Some dogs become more whiny or seek a lot of contact, while others seem restless. It is also common for the appetite to fluctuate. Some female dogs eat less for a few days, while others seem hungrier, and a couple of weeks after the heat some dogs show a false pregnancy with nest-building and tenderness. If you see strong signs of this, it is wise to discuss it with your vet.
Precisely because mood and appetite can fluctuate, it makes a difference to serve meals your dog is keen to tuck into. Fragrant and tasty dog meals with human-grade ingredients and fresh raw ingredients can tempt the appetite on the days when she is a little absent at the bowl. If you want to make the bowl extra inviting, a spoonful of an aromatic PÂTÉ prepared from exquisite ingredients can help entice even the fussy dog to clean the bowl.
How to create calm and good routines during the heat
The two to three weeks are best handled with predictability. Keep the walks on a lead and in places where you have an overview, because your dog can be scented from a long way off, and even a well-trained dog can become hard to call back when the hormones are raging. Preferably choose quiet times and routes where you will not run into a pack of loose male dogs. If you yourself have a male dog in the house, it may be necessary to keep the two separated during the days when your female dog is fertile.
Fixed routines around sleep, exercise and meals provide security when the body is otherwise in upheaval. Serve the meals at the usual times, and keep an eye on whether your dog is drinking and eating roughly as she usually does. A stable, well-balanced nutritional profile helps her keep her energy up throughout the period, and here it is an advantage to feed with well-considered, carefully composed meals, so you do not have to experiment with the diet in the middle of it all. If you are unsure about the feeding right now, you can always get in touch with ESSENTIAL FOODS' nutrition advisors, who are ready by phone, chat and email and are happy to help you find the right rhythm and the right meals for your dog.
Allow your dog to withdraw if she seeks more rest than usual, and meet her fluctuating mood with patience rather than reprimands. For most female dogs, the heat is a completely natural part of life, which passes on its own after a couple of weeks. With calm, fixed routines, supervision on the walk and meals she is keen to eat, you get through the period together most easily and most securely, until everything is back in its usual groove until the next time.