Vets explain 6 odd cat behaviors, from eating grass to sitting in the litter box

• Most cats have unique personalities and quirks — like eating grass or being picky about their food. 
• Sudden behavior changes, like hiding in the litter box or refusing to use it, could suggest stress. 
• Call a vet if your cat won't eat, strains to urinate, seems very lethargic, or has patchy hair.

Cats sometimes behave in puzzling ways — like running outside to chow down on grass and promptly throwing up. Or maybe they love to roll around with your shoes, or chill in their litter box instead of on the fancy cat furniture you got them. 

Of course, cats are curious, intelligent creatures, with individual personalities that make them unique. So, you might not always know for certain which odd behaviors fall into the category of "cat quirks" and which might suggest a health issue or other cause for concern. 

Most of the time, you don't have any reason to worry, since your feline pal is probably just doing cat things. When it comes to eating grass, for instance, experts have yet to link this behavior to any health issue. 

Read on to learn more about six common — but potentially confusing — cat behaviors and when you'll want to reach out to a veterinarian. 

1. Eating grass

There's no one accepted theory as to why cats like to eat grass, says Dr. Georgina Ushi, a veterinarian at Fuzzy, an online platform that connects pet parents remotely with vets. Research remains limited, but current theories suggest: 

• They may be trying to settle their tummies: "In small amounts, grass can act as a natural laxative, aid digestion, and prevent constipation," Ushi says.
• They may have a nutrient deficiency: Ushi says some experts theorize that cats may crave grass, which contains folic acid, to supplement a deficiency. But no hard evidence supports this.
• They like the taste: Some cats might nibble on grass because they just like the flavor, Ushi says.
• They may be trying to vomit: "Cats do not have the proper enzymes to digest grass," Ushi says. They may eat grass to help expel indigestible things like hairballs, though no current studies confirm this. 

If you're concerned about digestive issues or signs of a potential nutrient deficiency, like lethargy, appetite loss, or weight loss, your vet can offer more guidance and recommend tests for your pet. 

In short, cats eating grass is a fairly common behavior and probably not a big deal — unless they're munching on treated grass. 

If you treat your lawn with chemicals to kill weeds or insects, you'll want to keep your cat inside and off the grass. Eating treated grass — or walking on treated grass and then licking and grooming their paws — can make your cat very sick and may even be fatal. 

A few chemicals commonly in lawn care that pose a risk to cats include: 

• Glyphosate, a common weed killer
• Insecticides containing pyrethrins and pyrethroids, organophosphates, and carbamates 
• Ferrous sulphate, a moss killer 

A cat grass kit offers a safe alternative to chemically-treated lawns. These kits, which contain edible grasses like rye, wheat, or oat grass, make a great indoor option for cats that love nibbling on grass, according to Ushi. You can buy these kits online or in your local pet shop. 

2. Sneezing

Achoo! Yes, cats sneeze just like humans do — and often for many of the same reasons, Ushi says, such as:

• Airborne irritants like dust or chemicals: Irritants like dust or smoke, perfume, pollen, and cleaning products may all cause random sneezing. Foreign objects lodged in your cat's nose, like small pieces of kibble, can also make your cat sneeze, Ushi says.
• Upper respiratory infections: Symptoms of respiratory infections, including sneezing, nasal discharge and congestion, fever, and watery eyes, are similar to the human common cold, Ushi says. It's a good idea to reach out to a vet if you notice these symptoms in your cat.
• Sinus infection: According to Ushi, other signs of sinus infection include nasal congestion, green or yellow nasal discharge, and snorting or throat-clearing sounds. But this is less likely to cause sneezing, compared to upper respiratory infections. 
• Allergic rhinitis: This condition — called hay fever in humans —  happens when allergens like pollen or mold irritate the nasal passages. It's uncommon in cats, but it can cause sneezing, Ushi says. 

While sneezing due to airborne irritants doesn't typically require intervention, other causes of sneezing, such as infection, may require treatment from a vet. 

Ushi says your vet may recommend the following medications for chronic respiratory conditions, depending on whether the cause is bacterial or viral:

• Antibiotics 
• Antihistamines
• Saline drops
• Steroids
• Nebulization, or the delivery of medication, saline, or water in mist form to the lungs

3. Scratching or grooming constantly

All cats groom and scratch themselves to some degree. But overgrooming or excessive scratching can suggest an underlying medical issue or stress, says Molly DeVoss, certified feline training and behavior specialist. 

Signs of overgrooming may include:

• Bald spots or missing patches of hair
• Skin trauma due to overgrooming or scratching 
• Constant licking, biting, or chewing

DeVoss says scratching due to allergies typically ebbs and flows with exposure to allergens and the change of seasons. 

Other medical reasons for excessive scratching or grooming include: 

• Fleas or mites
• Atopic dermatitis
• Chronic urinary tract infections (UTIs) 

Cats might also overgroom due to anxiety, boredom, or obsessive-compulsive disorder (OCD), Ushi says. If your cat's overgrooming relates to stress, they'll likely have other behavioral symptoms. For instance, they might: 

• Have less interest in eating or drinking
• Meow more frequently
• Seem more withdrawn than usual 

Treatment for overgrooming involves addressing the underlying issue. For example, a cat with allergies that cause itchy skin may benefit from taking antihistamines. 

For behavioral overgrooming, DeVoss says identifying the trigger is crucial. Many cats have trouble with natural cat behaviors — grooming excessively or not at all, for instance — due to stress, DeVoss says. 

As a start, it may help to consider any changes in your cat's environment or daily life. For example, maybe you've recently spent more time away from home, changed their feeding time, or donated their favorite piece of furniture. 

4. Not eating

Sometimes, a lack of appetite can mean your cat is sick — but cats may also ignore their food because: 

• They don't like it: Cats have taste preferences, too, and they might refuse to eat if they don't like a certain flavor, Ushi says. She suggests offering a different diet to pique your cat's interest. "Most cats love wet food and will eat it with gusto," Ushi says.
• It's expired: If your cat suddenly seems uninterested in its usual meal, Ushi recommends checking the food's expiry date. Expired food may taste bad to your cat.
• They're saving it for later: "When most cat parents see their cat pawing to 'cover' their food, they think the cat doesn't like it," DeVoss says. But your cat may simply want to prevent other cats from sniffing it out so they can eat it later. 
• They have an underlying medical condition: If you've tried offering wet food or switching their kibble and your cat continues to turn the other way, Ushi recommends making a trip to the vet. She adds that it's crucial not to let your cat skip meals for more than two days. Ideally, contact a vet even sooner for guidance since a cat that's not eating can quickly become very ill.

5. Sitting in their litter box

Your cat sitting in their litter box may seem a little gross, but it's probably not a reason to worry. 

"Cats love to be in small cozy places. Some litter boxes provide that space for them, so they can rest, hide, and take a short break from play," Ushi says.

Additionally, DeVoss says cats gravitate toward familiar scents and that shelter cats often show a preference for a litter box filled with familiar smells. 

"In a home environment, a cat hiding or lying in the litter box could indicate a medical issue, feelings of stress, or territorial insecurity," she says. 

If your cat is sitting in a litter box for lengthy periods — over 12 hours at a time, for instance — something might be wrong, Ushi says. 

If you don't want your cat to hang out in their literal bathroom all day, you might try creating new, appealing hiding spots around your home. Aiming for variety can give your cat options. 

For instance, you might try a mix of: 

• Boxes
• A cushioned cat cave
• A window perch or cat hammock
• Cat trees with hiding cubbies

6. Urinating and defecating outside the litter box

One of the most common reasons cats do their business outside the litter box is a urinary issue. These include urinary cystitis, or an inflammation of the bladder wall, and urinary tract infections (UTIs). 

Signs your cat may have a urinary issue include:

• They strain while urinating and produce only small drops of urine. 
• They frequently try to urinate throughout the day.
• They cry while urinating.
• They won't stop licking their genital area.
• You can see blood in their urine.

Other potential medical reasons for this behavior include:

• Kidney disease
• Diabetes mellitus
• Thyroid disease
• Mobility or cognitive issues

Addressing underlying medical issues with the help of a veterinarian may prevent defecation and urination outside the litter box. 

Reasons for soiling outside the litter box aren't always medical, though. A cat may avoid the litter box because:

• They don't like it: Some cats may prefer a hooded box to an open one, or vice versa. A too-small box can also make it uncomfortable for them to do their business 
• They don't like its location: If the box is hard to access or doesn't offer enough privacy, your cat may find another place they prefer — like your closet or a dark corner.
• They don't like the litter material you chose: Cats tend to prefer unscented, clumping litter with a sand-like consistency. And while most manufacturers recommend using 2 to 3 inches of litter, you may need to experiment to find out what level best suits your cat.
• They're trying to mark their territory: Your cat may do this because they're in heat or threatened by something in their environment, like new cats in the home or nearby stray cats. 

Identifying non-medical reasons for skipping the litter box can take some time and experimentation. As a start, you might try changing the box, moving it, or opting for a different litter material to see how your cat responds. 

If your cat has a habit of marking its territory, your vet may recommend anti-anxiety drugs in addition to environmental changes. But medications don't offer a permanent solution, and they may not work for all cats.

When to contact your vet

Any major changes in your cat's behavior may suggest an underlying health concern. If you notice any of the following red flags, you'll want to make an appointment with your vet right away: 

• Your cat hasn't eaten in a day or longer.
• They seem unusually lethargic. 
• They haven't moved from the same spot in at least 12 hours.

Insider's takeaway

Weird behaviors like eating grass and ignoring food can be signs of underlying health issues, but your cat may also just be acting like a cat. 

Knowing their usual quirks can make it easier to spot signs of potential health problems. Keeping track of how much they usually eat and drink, for instance, can make it easier to recognize when they suddenly want more or less than usual. 

You can help your cat live a full, healthy life by making sure to keep tabs on their routine and habits, Ushi says. And it's always a good idea to schedule yearly vet visits and provide plenty of enrichment in the form of activities and toys.