How to know if Your Dog Is In Heat

Understanding your dog’s reproductive cycle is essential for responsible pet ownership, especially if you haven’t spayed your female dog. One of the most important phases in a female dog’s reproductive life is “heat,” also known as estrus. This is the time when she is fertile and can become pregnant. Recognizing the signs of heat can help you manage her health, prevent unwanted pregnancies, and avoid behavior issues. Here’s how to know if your dog is in heat:

1. Swollen Vulva

One of the earliest and most noticeable signs is a swollen vulva. This swelling typically appears a few days before any discharge begins and can last through most of the heat cycle. It may not be painful but is clearly visible and different from her usual appearance.

2. Bloody Vaginal Discharge

Another clear indicator is vaginal bleeding or discharge. The color can range from light pink to a darker red. This typically starts around the beginning of the heat cycle and may change in color and amount as the days go on. Some dogs clean themselves frequently, so you might not always notice the discharge unless you’re paying close attention.

3. Increased Urination

When in heat, dogs tend to urinate more often. This is partly because they are marking their territory to signal their fertility to male dogs. If your dog starts asking to go out more frequently or is having more accidents indoors, heat could be the cause.

4. Changes in Behavior

You may notice your dog becoming more affectionate, clingy, or, in some cases, more irritable. Behavioral changes vary between dogs—some become more playful and attention-seeking, while others may seem anxious or unsettled.

5. Attraction to Male Dogs

When in heat, female dogs become more appealing to males. You might notice male dogs hanging around your yard or trying to get close to her. She may also show increased interest in male dogs during walks or at the park.

6. Tail Positioning

As ovulation approaches, a female dog might move her tail to the side—this behavior, known as “flagging,” is a signal to male dogs that she’s ready to mate. If your dog starts lifting or shifting her tail when touched near the back, she might be in the fertile phase of her cycle.

The Heat Cycle Phases

To fully understand the signs, it’s helpful to know the phases of the heat cycle:

1. Proestrus (7–10 days): Swollen vulva, bloody discharge, attraction to males but won’t allow mating.

2. Estrus (5–10 days): Fertile period, lighter discharge, tail flagging, receptive to males.

3. Diestrus (10–140 days): Ends the fertile period; if pregnant, this is the gestation phase.

4. Anestrus (2–4 months): Resting phase before the next heat.

What You Should Do

• Prevent Unwanted Pregnancy: Keep her indoors or closely supervised.

• Hygiene: Use doggie diapers or cover furniture if there’s a lot of discharge.

• Track the Cycle: Note the start and end dates to predict future cycles (usually every 6–8 months).

• Consult Your Vet: If it’s her first heat or you notice unusual symptoms (e.g., excessive bleeding, lethargy), consult a veterinarian.

Final Thoughts

Recognizing when your dog is in heat helps you care for her more effectively and avoid complications. Whether you’re planning to breed or considering spaying, knowing the signs of estrus is an essential part of dog ownership. Always talk to your vet if you have concerns or questions about your dog’s reproductive health.