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How to Tell If Your Dog’s In Heat

ASPCA logoEstrus, or heat, is the stage in a female dog's reproductive cycle during which she becomes receptive to mating with males. At this time, estrogen levels first increase and then sharply decrease, and mature eggs are released from the ovaries. Ideally, your dog should be spayed before she enters her first heat cycle. 

 

When Does A Dog Experience Her First Estrus?

First estrus generally occurs when an unspayed female dog is between six and 24 months old. It tends to occur earlier for small-breed dogs and later for large-breed dogs.

How Often Do Dogs Go Into Heat?

Although it varies with different breeds and individual dogs, an unspayed female usually goes into heat twice yearly, about every six months.

How Long Does a Dog Stay in Heat?

The time during which male dogs are attracted to a female dog is variable, approximately 18 days. However, females are receptive to males for only about half of this time.

How Can I Tell if My Dog Is In Heat?

During estrus, your female dog may appear nervous, easily distracted and more alert than usual. She may also urinate more often than she normally does. You’ll most probably notice changes in her behavior; this is caused by a shift in her hormone balance. When a female dog is ready to be bred, she may initiate sexual interactions with other dogs, elevate her hind quarters toward males when they approach, deflect her tail to one side and tense her rear legs.
 
At first, vaginal discharge is blood-tinged and the vulva is swollen. When the female is receptive to males, vaginal discharge decreases in amount and is straw-colored.

How Can I Prevent My Dog From Going Into Heat?

It is highly recommended that you get your female dog spayed, not only to prevent estrus and accidental pregnancy, but to protect her against breast cancer and diseases of the reproductive system.

At What Age Can I Have My Dog Spayed?

Generally, a veterinarian can spay a dog when she is as young as two months old. However, it is best to consult with your veterinarian for specific recommendations regarding the best time to spay your dog.

Why Should I Spay My Dog?

Aside from the toll it takes on your dog to give birth to a litter and raise pups, the number of homeless animals who are euthanized each year makes it an irresponsible decision to allow your dog to mate. (This does not apply to those who are active in canine sporting events, and are knowledgeable about the care of pregnant dogs and nursing puppies.) Though many people have heard that there are health benefits in allowing a dog to have a litter before she is spayed, this belief is unsubstantiated. In fact, the rigors of giving birth and raising pups can lead to premature aging and, in some cases, death. It has also been shown that dogs who are spayed prior to their first heat cycle have a much reduced risk for mammary gland tumors.

 

WebMD Veterinary Reference from ASPCA Virtual Pet Behaviorist

The ASPCA Virtual Pet Behaviorist specializes in the resolution and management of pet behavior problems only. Please do not submit questions about medical problems here. Only licensed veterinarians can diagnose medical conditions. If you think that your pet is sick, injured or experiencing any kind of physical distress, please contact his veterinarian immediately. A delay in seeking proper veterinary care may worsen your pet's condition and put his life at risk. If you are concerned about the cost of veterinary care, please read our resources on finding financial help.

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