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Do cats get diarrhea when in heat?

Diarrhea is a common problem for cats. Heat causes changes in your cat physically and behaviorally, so it’s natural to wonder if there’s a link between the two. In most cases, diarrhea isn’t associated with your cat being in heat. 

Do cats get diarrhea when in heat?

Cats can get diarrhea when in heat. However, whether the diarrhea is caused by heat is another matter. 

What is Diarrhea?

Diarrhea is not a disease itself. Instead, it’s a symptom, or the result of another problem with your cat’s body. Once food is broken down by the stomach, it moves into the small intestine. The small intestine extracts nutrients from the food, and completes breaking it down. It then moves into the large intestine, before coming out as poop. 

Diarrhea causes the food to move through the digestive system quickly. The body doesn’t have a chance to break the food down properly. The moisture that would normally be extracted along with nutrients remains with the waste. This causes the poop to be thin and watery. 

What are the Signs of Diarrhea? 

The most well known sign of diarrhea is frequent pooping. If your cat poops more than 3 times a day, they likely have diarrhea. Diarrhea will also have a high water content. 

Normal poop will be well formed. With diarrhea, the consistency can be like soft serve ice cream or liquid. It will not be semi-solid like regular poop. This is due to the water present in the poop. 

In addition to frequency and loose stools, diarrhea can be hard to control. If you notice your cat pooping outside their letterbox, they may have diarrhea. 

It can be difficult to control the bowels long enough to reach the litterbox. Humans have the same problem with diarrhea, which can cause accidents. 

Cat Heat Cycle

Cats are polyestrus, which means they have several heat cycles each year. They begin their heat cycles between 4-12 months of age. Cats have heat cycles in the warmer months with longer days, typically January to October in the Northern Hemisphere. Cats near the equator or indoors can have heat cycles all year round. 

A cat will have a heat cycle every few weeks if they aren’t pregnant. The heat cycle can last for up to two weeks. If the cat didn’t breed, they will go into heat again about two weeks after the cycle ends. 

If they breed but don’t get pregnant, they will have another cycle about 4 weeks after their cycle stops. If they are pregnant, they will have a cycle about 8 weeks after giving birth. 

Changes When in Heat

When your cat enters her heat cycle, their body experiences changes. These are similar to the changes women experience with menstruation and pregnancy. Essentially, hormone levels change to create an ideal environment for pregnancy. 

The cat is receptive to males, and is able to ovulate during this time. Unlike humans, who ovulate monthly before their period, cats only ovulate when they have sex. 

When the cat has sex, usually a few times over hours to one day, it causes their body to release an egg. They can then get pregnant. Unlike dogs and humans, it’s impossible for them to get pregnant the first time they have sex. However, cats only take a few minutes to breed, so it’s easy for them to get several breeding sessions completed within a few hours. 

The fluctuations in hormones can cause stomach issues, but it’s unlikely. Women experience morning sickness during pregnancy due to hormone changes. Dogs can also experience vomiting and diarrhea during heat. However, cats don’t seem to have this issue. 

Stress and Anxiety

Heat itself is unlikely to give your kitty diarrhea. However, it can be an indirect cause. Heat is a stressful time for cats and their owners. Their hormones cause them to focus on the desire to breed. They will be restless and more easily stressed. 

Stress can cause stomach upset in your cat, just as it can in humans. The gut and brain are very closely connected. When the brain is stressed, it causes hormonal changes. These changes can overly stimulate the digestive system, causing food to pass through too quickly, causing diarrhea. 

Why might my cat have diarrhea?

There are several potential causes of diarrhea in cats. If your cat experiences diarrhea for more than two days, it’s best to seek your vet’s advice on the cause and treatment. 

Dietary Changes

A common cause of cat diarrhea is simply a change in diet or eating the wrong foods. Cats are unable to digest large amounts of grain, vegetables, and fruits, because they are naturally carnivorous. 

Switching your cat’s food can also cause diarrhea. When changing their food, it’s best to do so slowly. Begin feeding a small amount of the new food along with their current food. Gradually increase the amount of the new food and decrease the old, until they are completely on the new food. 

Milk is another dietary culprit. We all know cats love milk. However, their digestive system isn’t designed to digest it. Cow’s milk may seem like a treat for your cat, but it can give them diarrhea. If you want to give your cat milk, opt for goat’s milk. It’s easier to digest. You can also mix a little milk into some water. This is helpful if your cat doesn’t drink enough water. 

Bacterial or Viral Infection

You’ve probably experienced diarrhea from a virus or bacteria. It’s commonly called a stomach bug or a stomach flu. Cats are also susceptible to gastrointestinal diseases. 

In many cases, it will need to run its course. However, your vet may prescribe medication to manage the symptoms. If it’s a bacterial infection, antibiotics may be needed. 


Dogs and cats are susceptible to parasites. They are usually ingested in food or feces. Once they are inside your cat, they multiply rapidly. Other signs of parasites include dull coat, weight loss, and lethargy. You may also notice white spots or small worms in your kitty’s poop. These are dead worms being passed through the digestive system. 

Parasites can be treated with antiparasite medications. Preventatives can also be given to prevent your cat from getting parasites in the future.

Allergies and Food Intolerances

Just like humans, cats can have allergies or intolerances. The most common food allergens for cats are beef, fish, chicken, and dairy products. If you suspect food allergies are causing your kitty’s diarrhea, your vet may perform tests or an elimination diet to determine which foods they are allergic to. 


IBD stands for Inflammatory Bowel Disease. It is actually a cluster of diseases with multiple causes. However, the symptoms are the same regardless of the cause. 

Diarrhea is the most common symptom. Abdominal pain and vomiting are also common. A loss of appetite can occur. Sometimes the cat loses their appetite completely, which is understandably alarming. Blood in the stool and weight loss can also occur. 

If you suspect your cat has IBD, you’ll need to work with your vet to get a diagnosis and treatment plan. Severe cases of IBD can result in hospitalization and even death if not treated. 

Chronic Diseases 

Chronic diseases can also cause diarrhea. This type of diarrhea usually occurs on a regular basis. Your cat may have light diarrhea constantly, or experience bouts of diarrhea. Symptoms resolve, but come back a few days or weeks later. 

Liver disease, cancer, pancreatitis, and hyperthyroidism are common reasons for chronic diarrhea. What to do if my in season cat has diarrhea?

If your cat has diarrhea, you’ll need to pinpoint the cause if possible. Some causes must be treated. Other causes, like a virus, are treated by controlling the symptoms. 

When to Call the Vet

You’ll need to call your vet if your kitty has had diarrhea for two or more days. If your cat is exhibiting other symptoms, you may need emergency vet care. 

If your cat has a loss of appetite, fever, vomiting, or lethargy, call your vet immediately. If you notice blood in the stool or vomit, your cat needs immediate veterinary care. 

Home Treatment

There’s controversy about whether to withhold food when a cat has diarrhea. Some believe that it’s best to avoid feeding your cat, so their digestive system isn’t working too hard. Others point out that going more than 12 hours without food can cause stomach acid to build up. This can cause stomach pain and upset. 

Cats also need to eat frequent meals because of their body and metabolism. They don’t have the protein and fat stores most animals do. If they go too long without eating, they will begin to break down their muscle. 

It’s suggested to give a cat with diarrhea a bland diet. You can purchase specially formulated cat foods that are easier to digest. You can also feed them small amounts of boiled chicken, rice, and cooked oats.  

Always give a cat with diarrhea plenty of water. 

Your vet can prescribe antidiarrheal or anti-parasite medications if needed. Probiotics can also be beneficial, because they increase the good bacteria in the digestive system. 

Do cats show signs of illness when in heat?

Cats in heat shouldn’t have signs of illness. However, it can cause some changes that make them seem like they are sick. 

The most common reason owners think their cat is sick when in heat is their vocalizations. They will meow or yowl, sometimes incessantly. This is their way of calling for a mate, but it can sound as if they are in pain or not feeling well. 

Induced Ovulators

Cats are induced ovulators. This means that they don’t automatically ovulate when in heat. When they breed, typically several times over a 24 hour period, their body releases an egg. 

Humans, on the other hand, ovulate every month. They also shed their uterine lining with the unfertilized egg. This is what causes the symptoms of a period, including cramping and fatigue. Since a cat doesn’t shed their uterine lining during their cycle, they don’t experience these symptoms. 

Do cats behave differently when in heat?

Yes, cats have some natural behavioral changes when they are in heat. In fact, their changes in behavior is what will let you know when your cat is in season. 


As mentioned earlier, your cat will use their voice to call to potential mates. They can sound very distressed. It’s important to know that this isn’t because they are in pain. It’s simply their desire to mate. 


The desire to breed and hormonal changes also causes restlessness. Your cat may be anxious, or pace around the house. It’s natural for them to feel this way. You can help by giving them regular play sessions. Give them a new toy to help keep them entertained. 


Most cats become more affectionate during their heat cycle. You may notice that they want more attention. They may  be clingy, and want to be near you all the time. 

This scent lets males know that they are in heat. In addition to rubbing their head against you, they will rub it on objects as well. 

Desire to Go Outside

When your cat is in heat, she will have a strong desire to go outside. It’s normal for a cat in heat to roam, seeking mates. Cats are prolific breeders, and will breed with many males when given the opportunity. 

She may meow at the door or even attempt to sneak outside. This desire will also contribute to her restlessness. However, if she goes outside, she is likely to mate. 

Why does my indoor cat have diarrhea?

Your indoor cat can have diarrhea for any of the reasons listed earlier. However, they can also be exposed to toxic or poisonous substances within the home. 

House Plants

There are over 700 house plants that are toxic to cats. About 30 of these are very common houseplants. These include lilies and aloe vera. If your curious kitty takes a bite of a poisonous plant,it can give them diarrhea. 

Human Foods

Some human foods are safe for your cat in moderation, while others are harmful. Chocolate and garlic are a few of the foods you should never feed your cat. It can make them sick. When a cat ingests garlic or onions, it causes their body to attack their red blood cells. 

This can lead to anemia, and even death if the dose is high. In addition to diarrhea, the cat can experience vomitting, and red colored urine. 

Medications and Chemicals

Medications and chemicals, like those found in household chemicals, can also harm your cat. These things can cause diarrhea and vomiting because their body is attempting to expel the toxic substance.