It’s normal for an unspayed female dog’s vulva to become swollen during certain points in her heat cycle. The heat cycle involves four stages, and swelling occurs as the dog’s body prepares for mating and pregnancy. While some swelling is expected, excessive or prolonged swelling can indicate an underlying health issue requiring veterinary attention. This article will overview the stages of the heat cycle, explain why swelling happens, discuss how long it typically lasts, and provide guidance on identifying abnormal swelling requiring medical care.
The Heat Cycle
The heat cycle, known as estrous cycle, is the period when unspayed female dogs go through hormonal and physiological changes that prepare their body for pregnancy. It consists of 4 stages that last 2-3 weeks on average:
Proestrus: This initial stage lasts around 9 days. The dog’s vulva begins to swell and she will have some bloody vaginal discharge. Her estrogen levels start to rise, signaling that her heat period is starting. Though males will be attracted to her, she will not be receptive to breeding yet. [1]
Estrus: The estrus phase lasts approximately 9 days as well. The discharge lightens in color and the female is now receptive to mating with males. Her estrogen levels peak and progesterone levels start to increase. This is generally referred to as the most fertile point in her cycle. [2]
Diestrus: During this stage, lasting 50-60 days, the female dog is no longer receptive to mating. Her progesterone levels remain elevated which helps maintain pregnancy if conception occurred. The vulva gradually returns to a normal size. [3]
Anestrus: This phase means “without estrus” and signifies the end of the heat cycle, typically lasting 4-5 months. Hormone levels are low and the female has no sexual interest in males. Her reproductive system is at rest during this time as it prepares for the next cycle. [3]
When Does Swelling Occur?
Swelling of the vulva occurs during the estrus phase of the heat cycle, when the female dog is receptive to mating. This is because the increased levels of estrogen during estrus cause the vulva tissue to become inflamed and swollen. The swelling begins around the start of the estrus phase, which can last anywhere from 5-10 days on average.
It’s important to note that swelling can persist for weeks or even months after estrus ends. This is because the vulva tissue remains somewhat engorged and irritated after the heightened estrogen levels subside. The swelling may gradually reduce over time, but some dogs continue to show vulvar enlargement for extended periods following heat. This is especially true if the dog was actively breeding during that cycle.
So in summary, the significant vulvar swelling begins at estrus and can linger for an extend duration afterwards. This is a natural effect of the hormonal changes and breeding activity that occurs during heat.
Why Swelling Happens
Swelling occurs during a female dog’s heat cycle due to the increased levels of estrogen and progesterone as well as the production of prostaglandins. These hormones cause the vulva to enlarge and become softer as the body prepares for potential pregnancy. The vulva also becomes engorged with blood in order to facilitate mating and childbirth.
The rise in estrogen facilitates follicle growth in the ovaries and triggers physical changes in the reproductive system like vaginal swelling. Meanwhile, progesterone levels also increase to thicken the uterine lining in preparation for pregnancy. The combination of estrogen and progesterone leads to ovulation. After ovulation, if the female does not become pregnant, hormone levels drop, the swollen vulva returns to normal size, and the heat cycle ends.
Prostaglandins play a key role as well. These hormones are responsible for ovulation, luteolysis (the ending of the progesterone production), and the uterine and vaginal changes that support pregnancy. The high levels of prostaglandins during estrus cause smooth muscle tissue in the vulva to relax and fill with blood, leading to significant swelling.
In summary, swelling is a natural part of the canine heat cycle, allowing the female’s body to facilitate mating and prepare for potential pregnancy through the actions of estrogen, progesterone, and prostaglandins.1
Duration of Swelling
Swelling of the vulva and vaginal area can last for 1 to 3 months after a female dog’s heat cycle ends. This is because the dog’s body needs time for the reproductive organs to return to their normal size after being enlarged during the heat cycle. The Increased blood flow and estrogen levels that occur during the heat cause the vulva to become swollen, and it takes weeks for these levels to decrease back to normal.
According to veterinary experts, the swelling does not immediately go away once the heat cycle is over. The vulva remains somewhat enlarged for up to 8 weeks post-heat. It can then take an additional 4-8 weeks for the vulva to shrink down completely to its normal size. This means the total duration of swelling is approximately 1-3 months from the end of the heat cycle until the dog’s genital region appears normal again.
It’s important not to mistake prolonged swelling for a sign of a problem. As long as the dog is not showing signs of illness, soreness, or abnormal discharge, extended post-heat swelling is normal and no cause for concern. The vulva will gradually decrease in size and return to its pre-heat appearance over the course of the next few months. If the swelling persists longer than 3 months post-heat, veterinary examination is recommended.
Signs of Persistent Swelling
While some swelling after a heat cycle is normal, if the swelling does not go down within a few weeks, it could be a sign of a more serious condition that requires veterinary attention. You should note any discharge, pain, or abnormal swelling in your dog’s vulvar area and monitor it closely.
Some signs of problematic swelling to watch for include (Source 1):
- Ongoing redness, irritation, or inflammation of the vulva
- Unusual vaginal discharge that is green, yellow, or foul-smelling
- Licking or biting at the vulva due to discomfort
- Difficulty urinating or defecating
- Swelling that persists for longer than a month after the heat cycle ends
If you notice any of these signs along with vulvar swelling, it’s important to have your dog evaluated by a veterinarian. Persistent swelling could indicate conditions like vaginitis, vaginal tumors, or vaginal hyperplasia, which requires treatment (Source 2). Don’t hesitate to contact your vet if the swelling seems abnormal or just doesn’t go away on its own within a reasonable timeframe after your dog’s heat. It’s better to be safe than sorry when it comes to your canine companion’s health.
When to See the Vet
In most cases, the swelling after a female dog’s heat cycle will resolve on its own within a few weeks. However, if the swelling persists for longer than 2-3 months after the heat cycle ends, it’s a good idea to have your dog examined by a veterinarian.
Persistent swelling can indicate an underlying medical issue such as vaginal hyperplasia or an infection. Vaginal hyperplasia is overgrowth of vaginal tissue that causes the vulva to remain enlarged. It often develops as a result of repeated heat cycles and may require treatment with medication or surgery in some cases. Infections of the vagina or uterus can also lead to prolonged swelling and discharge.
Other signs that warrant a vet visit include discharge, pain, or your dog frequently licking the vulva area. Your vet can perform tests to determine if there is an infection present and provide appropriate treatment with antibiotics if needed.
It’s recommended to have your dog examined by a vet if the swelling lasts longer than 2-3 months after the heat cycle ends. Persistent swelling could indicate an underlying medical issue requiring treatment.
Treatment
Treatment will depend on the underlying cause of the prolonged swelling. The vet will start by doing a full physical exam to look for signs of infection, trauma, or abnormalities. They may collect samples for cultures to identify any bacteria present and perform diagnostic tests like vaginoscopy or biopsy to inspect the vaginal tissue.
If an infection is present, the vet will likely prescribe antibiotics suited to the type of bacteria identified. Common antibiotics used include amoxicillin, cephalosporins like cephalexin, or fluoroquinolones like enrofloxacin. Anti-inflammatories like carprofen may be given alongside antibiotics to reduce swelling and discomfort.
For dogs with vaginal hyperplasia or prolapse, the vet may recommend hormone therapy with prostaglandins to accelerate the end of the heat cycle. Topical anti-inflammatory creams containing hydrocortisone may also be prescribed. In severe cases of prolapse or tissue overgrowth, surgery may be required to remove excess tissue and repair the area.
If there are no signs of infection, the vet will likely recommend watchful waiting while monitoring for changes. They may suggest soothing topical washes or cold compresses to provide relief from swelling. Limiting activity, preventing licking of the area, and using Elizabethan collars can also help resolve swelling.
With appropriate treatment guided by diagnostic testing, most dogs recover well and swelling is resolved within several weeks after the heat cycle ends. Close follow up with the vet is important, especially if swelling persists despite initial treatment.
Prevention
It’s important to note that some swelling is a normal part of the heat cycle in female dogs. However, there are some steps you can take to help minimize discomfort for your dog:
Keep the vulva clean – Gently wipe the area with a warm, damp cloth to keep it clean. Avoid using soaps or cleaning products, which can further irritate the skin.
Use cold compresses – Applying a cold compress to the swollen area can help reduce inflammation and discomfort. Wrap an ice pack or frozen bag of peas in a towel and hold it against her vulva for 5-10 minutes at a time.
Give NSAIDs – Your vet may recommend non-steroidal anti-inflammatory drugs (NSAIDs), like Rimadyl, to help relieve swelling and pain. Only give medication prescribed by your vet.
Limit licking – Licking and chewing can further inflame the area. Use an Elizabethan collar to prevent access if licking becomes excessive.
Keep her comfortable – Let your dog rest in a quiet, comfortable area away from other pets. Anxiety and stress can potentially worsen symptoms.
Time spaying carefully – Spaying your dog while she is in heat can increase swelling. Discuss timing with your vet. Waiting until after the cycle may be best.
While you cannot completely prevent a heat cycle, you can help ease your dog’s discomfort using these tips. Contact your vet if swelling persists more than 2 months post-heat.
Conclusion
In summary, it’s normal for a female dog to experience some swelling of the vulva after going through a heat cycle. The swelling is caused by increased blood flow to the area and enlargement of the vulva. It usually peaks around the time ovulation occurs and then gradually subsides over the next few weeks after the cycle ends.
While mild, temporary swelling is normal, contact your vet if the swelling persists, seems excessive, or is accompanied by other concerning symptoms like discharge or pain. To help prevent prolonged swelling, keep your dog comfortable by avoiding intensive exercise and having her sleep in a cooler area during her heat cycle.
The key takeaways are that post-heat swelling is expected but should resolve within a few weeks. Seek veterinary advice if swelling is severe or persists longer than normal. With proper care and monitoring, your female dog can go through her cycles comfortably until the swelling subsides.
