When your female dog is receptive to mating, she is in a stage of her reproductive cycle known as being in “heat.” You can expect this to happen about twice a year beginning between six months to one year of age. Each time your dog goes into heat, the cycle will last about 21 to 28 days. However, each dog is different, so at what age her first heat cycle starts and how long she’s in heat can vary depending on the breed and size of the dog. Smaller dogs tend to have their first heat cycle earlier and large breed dogs later.
How Can I Tell If My Dog is in Heat?
In the event that you want to breed your dog or prevent a pregnancy, there are noticeable signs that can alert you that your dog is in heat:
First stage (proestrus). Your dog’s vulva will look swollen or larger than normal. This is usually accompanied by a bloody vaginal discharge and she may urinate more often. Your dog may display changes in behavior such as being jumpy or on edge. In this stage, she may hold her tail close to her body and shows no signs of wanting to breed. She may also become more clingy to you.
Second stage (estrus). This is the stage where she becomes ready to breed. The vaginal discharge may change from bloody to a clear or brownish discharge. You may also see your dog move her tail to the side, making herself available to a male dog. This is known as “flagging” and is a sign that she is fertile. These behaviors result from a fluctuation in her hormones. If you are interested in breeding your dog, your veterinarian can conduct a few tests during this stage that will determine if this is the best time to breed.
When your dog is in heat she gives off pheromones which a male dog can smell from miles away. Male dogs will become interested in her and may fight over her. Other female dogs may be aggressive toward her and she may be aggressive back. If you don’t want your dog mating with other dogs while she’s in heat, it’s important that you keep your dog away from male dogs during this time.
Note: There is a very serious complication that can occur after estrus called pyometra. This is an infection of the uterus so if your dog exhibits a pus-like discharge from her vulva, take her to your veterinarian immediately. This is an emergency situation and could even cause death.
Final stage (diestrus). During this stage your dog won’t be interested in mating anymore. The vaginal discharge will go away and her vulva will slowly shrink back to normal size. She might, however, behave as though she was pregnant but really isn’t. If you think your dog might be pregnant, it is important to visit your veterinarian at this time to confirm whether it is a true pregnancy versus a false pregnancy, which can signal a problem.
Should I Have my Dog Spayed?
Should you wish to avoid the situation of your dog going into heat altogether, spaying her before she has her first episode is the best course of action. There are many benefits of spaying your dog that you can discuss with your veterinarian.