If you’re a first-time dog owner and have an unspayed female, the prospect of caring for them during their season can be intimidating. Understanding how long dogs are in heat and what to expect during that time doesn’t just help you avoid an unplanned pregnancy. It means you can keep your dog comfortable and your home clean and plan for age-appropriate spaying or responsible breeding.
The full human reproductive cycle lasts an average of 28 days. Dogs don’t experience a monthly period, like humans do. Their reproductive cycle—commonly referred to as the heat cycle— is much longer than ours and broken down into four distinct phases.
“The key stages include proestrus (average of 9 days), estrus (average of 9 days), diestrus (average of 60 days), and anestrus (about 4 to 6 months),” Dr. Meera Gatlin, DVM, an assistant teaching professor of public health at Cummings School of Veterinary Medicine at Tufts University, explains.
However, Dr. Fran Smith, DVM, a board-certified theriogenologist (a specialty dedicated to animal reproduction) and AKC Breeder of Merit, points out that the timescales for both the proestrus and estrus stages are highly variable— both can range from 3 to 21 days.
During the proestrus phase, your dog’s eggs prepare for ovulation. Vulvar swelling and bloody discharge can occur, and male dogs start showing an interest.
©Mikkel Bigandt - stock.adobe.com
Estrus, commonly known as “in season” or “on standing heat”, is when females are receptive to mating. “The fertile portion of the cycle occurs from a couple of days before ovulation to 5 days after,” Dr. Smith says. While vulvar swelling continues during estrus, the bloody discharge often decreases and becomes more watery and pinkish.
During the diestrus phase, your dog is no longer fertile, and their vulvar swelling and discharge should stop, even though progesterone (the pregnancy-supporting hormone) continues to rise during this stage. This rise in hormones is what causes some dogs to show signs of false pregnancies, such as nesting behaviors and swollen, sometimes lactating mammary glands.
During the long anestrus stage, reproduction hormone levels are low, and the body rests and repairs in readiness for the cycle to begin again.
“Dogs go into heat approximately every 6 months, and factors such as pregnancy, drug exposures, infectious diseases, and underlying health conditions can affect the duration,” Dr. Gatlin says. Age, size and breed type can also play a part.
“First-time cycles can have split heats,” adds Dr. Gatlin. This is because young dogs can’t produce sufficient hormones to ovulate. In these instances, the estrus stage is interrupted and typically resumes within a few weeks. She says small dogs can have silent heats (where the typical signs, such as vulvar swelling and discharge, are not seen), and larger dogs can have less frequent heat cycles.
While most female dogs cycle twice a year, Dr. Smith says the exception to this is some of the primitive breeds. “The Basenji is the trademark for this—they only cycle once a year,” she says.
When your female dog reaches sexual maturity and experiences their first heat cycle varies widely depending on their breed type and size. “For toy breed dogs, it might be as early as 4 or 5 months,” Dr. Smith says. “For the big sighthounds, like the [Scottish] Deerhound or [Irish] Wolfhound, or a Great Dane, it might not be until they are 2.”
Ekaterina Krivtsova/Shutterstock
Dogs don’t experience menopause like human females, meaning they continue to have heat cycles and the ability to get pregnant into their senior years. They don’t necessarily have longer gaps between cycles either, although Dr. Smith says dogs become less fertile, and their heat can become silent. “This means they don’t have vulvar swelling or bloody discharge, but they do still cycle and ovulate,” she says.
Vulvar swelling, vaginal discharge and attraction of male dogs are the most common signs of female dogs in heat. You might also notice hormonally-mediated behavior changes. “Some females become kind of spooky, others are over-friendly, and some are aggressive with other dogs,” Dr. Smith says.
“From personal experience, my own dog predictably was unwell during her heats,” says Dr. Laurence Sawyer, DVM, assistant teaching professor in the department of clinical sciences and medical director of the Lerner Spay/Neuter Clinic at Cummings School of Veterinary at Tufts University. “She would become inappetent, lose weight, and develop a urinary tract infection every time she cycled.”
When your female dog is ready to be mated during the estrus phase, you might see tail flagging if they come into contact with a male dog. This is when they hold their tail to the side to communicate they are ready for mating.
Dr. Smith says there is no evidence that dogs experience premenstrual cramps as humans do. However, maintaining a routine, providing comfort when your dog is looking for it, and respecting their space if they are more withdrawn can help to manage any behavioral anxieties they develop due to the hormone changes.
Doggy diapers protect your furniture and floors—just don’t rely on them as a form of contraception.
While rare, there is a risk of unspayed dogs, particularly seniors, developing a potentially life-threatening infection of the uterus known as pyometra. This typically occurs 4 weeks to 4 months after a heat cycle. Tracking how long your dog’s heat cycle lasts and watching for the early signs of this disease increases the chance of catching pyometra before it progresses too far.
Photoboyko/Getty Images Plus
“Things owners should watch for include increased thirst, increased urination, sometimes an increase in appetite and a decrease in energy,” Dr. Smith says. “From a cost standpoint, spaying a female with a pyometra is four to five times more expensive and much more dangerous than spaying a young, healthy female.”
While ‘mismate’ injectable hormone preparations designed to prevent a pregnancy from developing after accidental mating, Dr. Smith says they gave varying degrees of safety and success.
Instead, she says being vigilant and keeping your unspayed female dog on leash is the most effective way to prevent unwanted pregnancy when they are in heat.
Dr. Smith also cautions against tying your dog up in the yard. “When a female is in heat, if you walk her on a leash, the male dog can track her all the way home based on the hormones in her urine,” she says. Even if your yard is fenced, never underestimate the determination of an intact male dog once they have that scent.
Spaying your female dog means they won’t be able to get pregnant. This is typically done after they reach sexual maturity and experience at least one heat cycle. “Prepubertal spaying (or neutering) delays or interferes with the closure of the growth plates in dogs, making them more likely to experience orthopedic disease, and, depending upon the breed, also increases the risk of some cancers,” Dr. Smith says.
However, she explains it’s all about weighing up the risk versus the benefit. “In a shelter or rescue situation, if the benefit of the early spay or neuter means that the dog might get a home, it can be worth it.”
©Canadeez - stock.adobe.com
Dr. Smith says that progesterone testing is the most effective way for responsible breeders to establish ovulation timing. “It’s a misconception that if you breed a dog on day 10 to 12 of her cycle, you will succeed,” she says.
What we do know is that female dogs ovulate approximately two days after the ovary-stimulating luteinizing hormone (LH) peak. There isn’t a good, readily available test for LH. However, Dr. Smith says that most experts accept that the LHP is associated with a progesterone level of 2.0 nanograms per ml, and, theoretically, a dog should ovulate 2 days after reaching this level. “However, that range is individualized, and some bitches fail to ovulate,” she cautions.
Dr. Smith says dogs are most fertile between ages 2 and 4 “The female is born with all the eggs she will have, and as she ages with cycles, the number of eggs she has left in her ovaries drop off,” she says. As a dog ages and becomes less fertile, there is an increased risk that they won’t get pregnant, and if they do, they can have a more difficult time giving birth and typically lose more puppies.
The post How Long Are Dogs in Heat? appeared first on American Kennel Club.
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What Are the Stages of a Dog’s Heat Cycle?
The full human reproductive cycle lasts an average of 28 days. Dogs don’t experience a monthly period, like humans do. Their reproductive cycle—commonly referred to as the heat cycle— is much longer than ours and broken down into four distinct phases.
“The key stages include proestrus (average of 9 days), estrus (average of 9 days), diestrus (average of 60 days), and anestrus (about 4 to 6 months),” Dr. Meera Gatlin, DVM, an assistant teaching professor of public health at Cummings School of Veterinary Medicine at Tufts University, explains.
However, Dr. Fran Smith, DVM, a board-certified theriogenologist (a specialty dedicated to animal reproduction) and AKC Breeder of Merit, points out that the timescales for both the proestrus and estrus stages are highly variable— both can range from 3 to 21 days.
During the proestrus phase, your dog’s eggs prepare for ovulation. Vulvar swelling and bloody discharge can occur, and male dogs start showing an interest.
©Mikkel Bigandt - stock.adobe.com
Estrus, commonly known as “in season” or “on standing heat”, is when females are receptive to mating. “The fertile portion of the cycle occurs from a couple of days before ovulation to 5 days after,” Dr. Smith says. While vulvar swelling continues during estrus, the bloody discharge often decreases and becomes more watery and pinkish.
During the diestrus phase, your dog is no longer fertile, and their vulvar swelling and discharge should stop, even though progesterone (the pregnancy-supporting hormone) continues to rise during this stage. This rise in hormones is what causes some dogs to show signs of false pregnancies, such as nesting behaviors and swollen, sometimes lactating mammary glands.
During the long anestrus stage, reproduction hormone levels are low, and the body rests and repairs in readiness for the cycle to begin again.
What Factors Can Influence a Dog’s Heat Cycle?
“Dogs go into heat approximately every 6 months, and factors such as pregnancy, drug exposures, infectious diseases, and underlying health conditions can affect the duration,” Dr. Gatlin says. Age, size and breed type can also play a part.
“First-time cycles can have split heats,” adds Dr. Gatlin. This is because young dogs can’t produce sufficient hormones to ovulate. In these instances, the estrus stage is interrupted and typically resumes within a few weeks. She says small dogs can have silent heats (where the typical signs, such as vulvar swelling and discharge, are not seen), and larger dogs can have less frequent heat cycles.
While most female dogs cycle twice a year, Dr. Smith says the exception to this is some of the primitive breeds. “The Basenji is the trademark for this—they only cycle once a year,” she says.
When Do Dogs First Go Into Heat?
When your female dog reaches sexual maturity and experiences their first heat cycle varies widely depending on their breed type and size. “For toy breed dogs, it might be as early as 4 or 5 months,” Dr. Smith says. “For the big sighthounds, like the [Scottish] Deerhound or [Irish] Wolfhound, or a Great Dane, it might not be until they are 2.”
Ekaterina Krivtsova/Shutterstock
When Do Dogs Stop Going Into Heat?
Dogs don’t experience menopause like human females, meaning they continue to have heat cycles and the ability to get pregnant into their senior years. They don’t necessarily have longer gaps between cycles either, although Dr. Smith says dogs become less fertile, and their heat can become silent. “This means they don’t have vulvar swelling or bloody discharge, but they do still cycle and ovulate,” she says.
How to Tell if My Dog is In Heat
Vulvar swelling, vaginal discharge and attraction of male dogs are the most common signs of female dogs in heat. You might also notice hormonally-mediated behavior changes. “Some females become kind of spooky, others are over-friendly, and some are aggressive with other dogs,” Dr. Smith says.
“From personal experience, my own dog predictably was unwell during her heats,” says Dr. Laurence Sawyer, DVM, assistant teaching professor in the department of clinical sciences and medical director of the Lerner Spay/Neuter Clinic at Cummings School of Veterinary at Tufts University. “She would become inappetent, lose weight, and develop a urinary tract infection every time she cycled.”
When your female dog is ready to be mated during the estrus phase, you might see tail flagging if they come into contact with a male dog. This is when they hold their tail to the side to communicate they are ready for mating.
How to Care For a Dog In Heat
Dr. Smith says there is no evidence that dogs experience premenstrual cramps as humans do. However, maintaining a routine, providing comfort when your dog is looking for it, and respecting their space if they are more withdrawn can help to manage any behavioral anxieties they develop due to the hormone changes.
Doggy diapers protect your furniture and floors—just don’t rely on them as a form of contraception.
While rare, there is a risk of unspayed dogs, particularly seniors, developing a potentially life-threatening infection of the uterus known as pyometra. This typically occurs 4 weeks to 4 months after a heat cycle. Tracking how long your dog’s heat cycle lasts and watching for the early signs of this disease increases the chance of catching pyometra before it progresses too far.
Photoboyko/Getty Images Plus
“Things owners should watch for include increased thirst, increased urination, sometimes an increase in appetite and a decrease in energy,” Dr. Smith says. “From a cost standpoint, spaying a female with a pyometra is four to five times more expensive and much more dangerous than spaying a young, healthy female.”
How to Prevent Pregnancy When a Dog Is in Heat
While ‘mismate’ injectable hormone preparations designed to prevent a pregnancy from developing after accidental mating, Dr. Smith says they gave varying degrees of safety and success.
Instead, she says being vigilant and keeping your unspayed female dog on leash is the most effective way to prevent unwanted pregnancy when they are in heat.
Dr. Smith also cautions against tying your dog up in the yard. “When a female is in heat, if you walk her on a leash, the male dog can track her all the way home based on the hormones in her urine,” she says. Even if your yard is fenced, never underestimate the determination of an intact male dog once they have that scent.
Spaying your female dog means they won’t be able to get pregnant. This is typically done after they reach sexual maturity and experience at least one heat cycle. “Prepubertal spaying (or neutering) delays or interferes with the closure of the growth plates in dogs, making them more likely to experience orthopedic disease, and, depending upon the breed, also increases the risk of some cancers,” Dr. Smith says.
However, she explains it’s all about weighing up the risk versus the benefit. “In a shelter or rescue situation, if the benefit of the early spay or neuter means that the dog might get a home, it can be worth it.”
©Canadeez - stock.adobe.com
When Is the Best Time to Breed?
Dr. Smith says that progesterone testing is the most effective way for responsible breeders to establish ovulation timing. “It’s a misconception that if you breed a dog on day 10 to 12 of her cycle, you will succeed,” she says.
What we do know is that female dogs ovulate approximately two days after the ovary-stimulating luteinizing hormone (LH) peak. There isn’t a good, readily available test for LH. However, Dr. Smith says that most experts accept that the LHP is associated with a progesterone level of 2.0 nanograms per ml, and, theoretically, a dog should ovulate 2 days after reaching this level. “However, that range is individualized, and some bitches fail to ovulate,” she cautions.
Dr. Smith says dogs are most fertile between ages 2 and 4 “The female is born with all the eggs she will have, and as she ages with cycles, the number of eggs she has left in her ovaries drop off,” she says. As a dog ages and becomes less fertile, there is an increased risk that they won’t get pregnant, and if they do, they can have a more difficult time giving birth and typically lose more puppies.
The post How Long Are Dogs in Heat? appeared first on American Kennel Club.
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