Getting a new puppy comes with a lot of responsibilities, and if you choose a female puppy, those responsibilities include being prepared for her first estrus, or "heat" cycle. Depending on her breed and size, your dog can reach sexual maturity and go into heat as early as 4 months of age. This means she will be receptive to mating and can become pregnant even if she is not fully grown. You will often see spellings as both "estrous" and "estrus." Veterinarians refer to the entire reproductive cycle as "estrous" and the "receptive to being bred" part of that cycle is "estrus" or "in heat."
If you are not a breeder, consider leaving it to the professionals and talk to your veterinarian about having your female dog spayed. Spaying, or ovariohysterectomy, can have many benefits beyond preventing heat cycles and unwanted pregnancy, including eliminating or reducing the likelihood of health issues, such as pyometra (a uterine infection that can be fatal) and mammary cancer.
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For pet owners who do decide to leave their female dog intact (unspayed), it is important to be knowledgeable about your dog's reproductive cycle, including the timing of estrus, how to prevent accidental pregnancies, and ways to comfort and protect your dog when she's in heat.
When do dogs go into heat?
Some small female dogs will experience their first estrous cycle as early as 4 months of age. Giant dog breeds might not go into heat until they are 1 year or older, and most medium and large breeds will have their first heat at about 6 months old. The entire cycle will last about 14 to 24 days (although it can be shorter or longer), and a dog will most likely have two cycles per year. The rest of the year, she will be in what is called anestrus, and she will not be receptive to mating.
It is never advisable to breed a young puppy, as her body is still developing, and serious complications can occur. Ask your veterinarian for advice on the appropriate age for your dog to have her first litter.
Take special precautions while your puppy is in heat, such as not allowing her to come into contact with intact males (dogs who have not been neutered), even for short periods of time. Avoid dog parks and walks or off-leash time in public areas. Keep the gate to your yard closed, go outside with her while she relieves herself, and do not leave her unattended. Male dogs will be attracted to the female's scent and will seek her out at all costs, even jumping fences or chewing through screen doors to get to her.
Signs of a dog in heat
Watch for signs that your female puppy is about to experience her first heat cycle. Keep in mind that the first estrus can be "silent," meaning you might not notice any signs at all the first time. If your dog does display signs, you might observe the following:
- Swollen vulva/genital area
- Bloody discharge from the vulva
- Changes in your dog's behavior (acting unusually nervous or aggressive; mounting or "humping" other pets, people, or items)
- Excessive licking of the genitals
- Frequent urination
Be aware that if your dog is licking her genitals and urinating more often, this could also be a sign of a urinary tract infection, so make an appointment with your veterinarian if you are not sure.
How to prepare for a dog in heat
If you suspect your puppy will soon have her first estrous cycle, there are a few things you can do to get ready:
- Learn about how the heat cycle works. Get educated on the different phases of canine estrus, including proestrus, estrus, and diestrus, so you'll know what to expect.
- Have your supplies prepared ahead of time. Your list should include wee wee pads for your dog's crate or living area, unscented baby wipes for cleaning your puppy, and canine diapers to absorb blood and discharge and protect your floors and furniture.
- Plan ahead. Decide who will clean and change your dog every few hours and who will look after her to ensure that intact males don't have access to her.
How to comfort a dog in heat
A puppy in heat, especially during her first estrus, might be anxious or confused. It can also be a nerve-wracking time for you as the owner, but it is important to stay calm in order to soothe your puppy. Here are some more things you can do to comfort your dog:
- Speak softly and give her extra attention and cuddles.
- Give her tummy rubs and gentle massages behind the ears.
- Brush her coat to relax her (if she enjoys being groomed).
- Make sure she has a space of her own. Some dogs do not like being around other pets while they are in heat.
- Try a calming aid specifically for canines, such as a pheromone diffuser, calming collar, or anti-anxiety supplement. Ask your veterinarian about what might be best, especially before starting any calming medications or supplements.
Cleaning tips for dogs in heat
Your puppy has an instinct to clean herself, and this will not go away while she is in heat. It is a good idea to remove your dog's diaper for at least a few minutes a day to allow her to clean herself. You should also check your dog's fur daily, especially around the genitals, for any dried, crusted blood or discharge. Use unscented baby wipes or dog grooming wipes to gently remove debris. For your home, keep a pet-safe cleaning solution on hand, such as Nature's Miracle, to take care of any unexpected messes.
The bottom line
If you have an unspayed female puppy, expect her to have her first estrous cycle between 4 and 6 months old. If you are not planning to breed your dog, it is a good idea to consult your veterinarian about the right time to have her spayed. Otherwise, be prepared for your pet to have a cycle, which can include vaginal discharge and bleeding, about twice a year. To make this time easier for both you and your puppy, it is helpful to learn about the different phases of a dog's estrous cycle; stock up on supplies, such as doggy diapers, wipes, and cleaning products; and talk to your veterinarian about ways to keep your pet calm when she is in heat. It is also important to prevent unneutered male dogs from having access to your puppy during her estrous cycle.