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Often Overlooked yet Common Causes of Frequent Vomiting

Chronic vomiting in cats has become so common that many owners and even some veterinarians don't consider it to be a problem. However, it's stressful and physically taxing for kitty, and cleaning up is never fun. These two often-ignored factors may be at the top of the list of causes for vomiting.

why do cats throw up so much

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  • Many cats today vomit so often it isn’t considered abnormal; however, regular vomiting is a sign something’s wrong
  • A common cause of frequent vomiting in cats is a poor-quality diet and food intolerances, both of which must be addressed to resolve the issue
  • Eating too fast and too much time between meals can cause vomiting, as can hairballs and constipation
  • Enzyme deficiencies, toxin ingestion, and an underlying medical condition can also play a role
  • Helping a chronically vomiting cat requires identifying the cause(s), addressing any underlying medical issues, and making appropriate dietary/lifestyle changes

Editor's Note: This article is a reprint. It was originally published November 09, 2021.

Chronic vomiting in cats is unfortunately so common these days that many pet parents and even some veterinarians don’t consider it a big deal. However, the reality is that regular vomiting is a sign something’s wrong, since your kitty’s cousins in the wild don't routinely vomit. It’s also important to realize that frequent vomiting is stressful and physically taxing.

You can be sure your poor cat doesn’t enjoy doing it any more than you enjoy the clean-up chore. Common causes of chronic vomiting in kitties include:

  1. Poor diet and food intolerances
  2. Eating too fast
  3. Too much time in between meals
  4. Hairballs (wild cats don’t get these routinely, either), constipation
  5. Enzyme deficiencies
  6. An underlying medical condition
  7. Toxin ingestion

Cause No. 1: A Poor-Quality Diet and Food Intolerances

Cats fed ultraprocessed diets may vomit due to poor quality, biologically inappropriate ingredients. Rendered ingredients that wind up in pet food are leftovers from the human food industry and can include animal pieces and parts like bird feathers, snouts, beaks, eyes, hooves and nails. Some of these pieces and parts can be highly nutritious, but some can be condemned tissues, including abscesses and tumors; with feed grade ingredients, you just don’t know.

Some of these can be very low-quality ingredients with poor bioavailability that are difficult for cats to digest, causing gastrointestinal (GI) upset. Whereas dogs typically have lower GI issues (colitis) and are more apt to develop diarrhea, kitties tend to have upper GI issues (enteritis — inflammation of the small intestine), so they vomit.

Since the introduction of ultraprocessed pet food, many cats have been fed diets that are not species-specific, which has led to a chronically disrupted microbiome, dysbiosis, and in turn, the development of a myriad of chronic reactions, including food intolerances and allergies — a very common reason for intermittent vomiting over a period of months or years.

If your kitty is at a healthy weight with a normal energy level, but just throws up occasionally, food sensitivity could be the culprit. Food sensitivities develop when the same foods are fed over and over to an animal with a leaky gut, which happens a lot with cats because they get addicted to certain foods and refuse to eat anything else.

Feeding the same type of protein, even if it's excellent human-grade quality, can over time create GI inflammation and food sensitivities. So, it's not just about feeding good quality protein, but also nutritional diversity and switching proteins frequently, which is important for developing and maintaining a diverse microbiome.

I recommend transitioning cats with GI upset to human-grade cat food (which unfortunately can be very difficult to find), and ultimately to a fresh food diet.

I prefer a raw diet for cats who will eat it, but even gently cooked fresh food is a huge improvement over ultraprocessed, feed grade junk food. I also recommend transitioning to a different protein every three to four months to avoid hypersensitivity reactions (click here to watch my Facebook Live about how to transition even the finickiest cat to fresh food).

If you believe your cat may have a food hypersensitivity or allergy, I recommend the NutriScan saliva test, which can provide help in choosing a diet to which your cat is less reactive.

The good news is I've found that correcting food sensitivities, removing noxious or unnecessary ingredients from the diet, as well as transition­ing to a species-specific, fresh, clean diet eliminates most of the common causes of vomiting in cats. Analyzing and correcting your cat’s microbiome imbalances can resolve many chronic gut issues, as well.

If you feed treats, be sure they’re high-quality. Better yet, make homemade cat treats. You don't want to spend money upgrading your cat’s diet and then feed junky treats. In store-bought treats, look carefully at the label and avoid anything containing propylene glycol, dyes or colors, ethoxyquin, chemical dyes, emulsifiers, surfactants, and other questionable ingredients (be suspicious of ingredients you can’t pronounce).

All those additives, preservatives and other chemicals can cause GI inflammation and vomiting. I recommend buying organic, GMO-free foods and treats to eliminate glyphosate pesticide residues, as well.

It’s also important to note that contrary to what many people think, cats don’t need milk. Animals are best suited to digest and process milk from their own species. Drinking the milk of a different species past weaning can cause or exacerbate GI inflammation, especially if there’s underlying dysbiosis. If your cat can't tolerate cow's milk, it can cause vomiting.

Cause No. 2: Eating Too Fast

Another very common reason cats throw up is from eating too fast. Your cat's esophagus is horizontal and flat. Everything he swallows must travel horizontally before it moves into the stomach. If he’s in the habit of speed eating, food can back up in the esophagus and push against the lower esophageal sphincter.

This can result in regurgitation of part or all of the meal, undigested, within moments of swallowing. This behavior is seen most often in multi-cat households in which everyone’s fed in the same area at the same time, which can spark competition.

There's usually at least one speed eater in the group, and when the food bowls hit the floor, he scarfs his own meal in seconds and then races to everyone else's bowl to see about leftovers. He's such a little glutton that he often ends up returning all that hastily eaten food to the floor.

You can reduce digestive and social stress in multi-cat homes by feeding your cats in separate areas so they can't see or hear the others eat. It's best if you can close the door behind each cat, because it won't take long for your overeater to figure out where the rest of the bowls are if he can still get to them.

Give everyone about 20 minutes of solitude to eat their food slowly and uninterrupted, then remove the bowls. This may slow down your gobbler, reduce or eliminate the vomiting and keep him from getting fat. It also allows your slower-eating kitties to relax while they dine.

If you have just one cat but she's a speed eater, you may need to split her meals into smaller portions and feed her more often, so the food doesn't come right back up. You can also use a mini-muffin tin to slow her down. Just put a bit of food in each individual muffin cup. Moving from cup to cup will naturally slow her down.

You can also try spreading the food out over a large cookie or baking sheet. If you prefer something more high-tech, there are slow-feed bowls you can purchase that provide essentially the same benefit.

My favorite way to feed cats is with food dispensing “mice” that are hidden around the house. This mimics their natural hunting instincts because it’s more mentally and physically engaging, requiring cats to move their bodies a little more to find their food.

Cause No. 3: Too Much Time Between Meals

Cats fed on a regular schedule, for example, at 7:00 AM and 5:00 PM each day, tend to start looking for their meal an hour or so earlier because their bodies know it's getting to be that time. Around the same time, your cat's stomach begins releasing digestive substances like hydrochloric acid, gastric juices, and bile in anticipation of the upcoming meal.

If you're late with her meal, she may throw up a white foamy liquid mixed with a bit of yellow bile. This is because the digestive substances irritate the lining of the stomach when there's nothing in there for them to work on, so your cat's body gets rid of some of the acid to prevent further irritation.

If this is the situation with your cat, give her a little something to snack on before you feed her, like a treat or a small bite of her meal. Using food-dispensing toys with tiny morsels of food in between meals can also be beneficial; this will give her stomach juices something to digest and should alleviate the vomiting.

Cause No. 4: Hairballs and Constipation

If your cat is vomiting hairballs, instead of “balls,” you'll see cylindrical wads of hair and debris, probably some undigested bits of food, and usually a little phlegm to hold the revolting mess together. Long-haired cats and kitties who are over groomers typically have more hairball issues than normal.

Cats fed kibble don't get enough moisture in their diet, so their organs tend not to function as efficiently as they should. And unlike dogs, kitties don't make up the deficiency by drinking lots of water, so they often end up chronically mildly dehydrated.

A GI tract that is moisture-depleted is less able to transport a hairball than the digestive tract of a well-hydrated cat eating a species-specific diet. Kibble is also deficient in omega-3 fatty acids, which results in excessive shedding.

It’s important to note that cats in the wild pass hair in their feces on a regular basis. Felines have tiny bristles on their tongues and are designed to process swallowed hair. Recurrent hairballs are abnormal.

To help prevent your cat from swallowing so much hair that it forms hairballs in his GI tract, you'll need to brush him regularly, especially if he’s over grooming. If he’s grooming everyone in a multi-cat household, you'll also need to brush the other kitties.

If your cat is eating exclusively dry food and you can't or aren't willing to switch to a different diet, I recommend rehydrating his dry food with bone broth, which can help with constipation and hairballs. Kibble fed cats may need additional GI lubrication to help ingested hair pass through the digestive tract. I find a pinch of fiber and coconut oil together is a good combination for recurrent hairballs, or a petroleum-free hairball remedy.

If hair passes through the stomach and into the intestines it can cause constipation. There are a multitude of other reasons cats get constipated, but many, regardless of the reason, begin vomiting because their elimination system is clogged up.

Cause No. 5: Enzyme Deficiencies

Sometimes a kitty’s pancreas doesn't produce enough digestive enzymes, such as lipase, protease, and amylase, which can result in acute or chronic pancreatitis. Pancreatitis (inflammation of the pancreas) is very common in cats, and even if there are no other obvious symptoms, can be an underlying cause of intermittent vomiting.

Cats evolved to eat an entirely fresh food diet, primarily mice and other small prey, which is a very rich source of digestive enzymes that is entirely missing from ultraprocessed cat food. That's why I recommend adding a digestive enzyme to your cat's diet.

If your kitty's pancreas is producing adequate enzymes, adding additional enzymes to her food won't cause any problems. However, if her pancreas is not secreting sufficient enzymes, supplementing ensures she'll have what her body needs to process her food. Providing a high-quality digestive enzyme can help reduce vomiting as well as the potential for pancreatitis.

Cause No. 6: A Serious Underlying Medical Condition

A 2013 study published in the Journal of the American Veterinary Medical Association took a critical look at chronic vomiting (defined as vomiting two or more times per month, including hairballs) in cats and revealed some important findings, including:1

  • Chronic vomiting is usually due to disease of the small intestine (small bowel) instead of the stomach.
  • Chronic small bowel disease (CSBD) not only involves frequent vomiting but also weight loss and/or chronic diarrhea. It causes thickening of the small intestinal wall that can be documented with a noninvasive ultrasound study.
  • Thickening of the small bowel wall results in a decreased ability of the muscles in the small bowel wall to contract properly. This results in slow passage of food and hair downstream.
  • When the cat eats, the small bowel is often still full of food from the prior meal, so vomiting results.
  • As the wall thickens further, the cat loses her ability to absorb nutrients. This leads to weight loss and a compensatory increase in appetite she tries to make up for the weight loss.
  • Undigested or unassimilated food that remains in the small intestine can result in chronic diarrhea. As veterinarian Dr. Gary Norsworthy, lead study author wrote in a 2016 article:

    “There are two diseases that account for more than 95% of the cases of CSBD. One is inflammatory bowel disease (IBD), resulting in the small bowel walls being packed with inflammatory cells. This disease is much like IBS (irritable bowel syndrome) in people. The other disease is lymphoma, a form of cancer. The walls of the small bowel are packed with lymphoma (cancer) cells.

    The cause of the inflammation of either disease is unknown. Both of these diseases are progressive, meaning they get worse over time. In fact, mounting evidence shows there is a transition in some cats from IBD to lymphoma. This is one of the main reasons that an aggressive approach to getting a diagnosis is important.”2

In addition to lymphoma, other types of GI cancers can also cause vomiting, as can metabolic disorders like hyperthyroidism, which is a very common disease diagnosed in older cats. Organ disease or a malfunction of the organs of detoxification, including the liver and the kidneys, will also cause vomiting.

Your veterinarian should first rule out all potential medical reasons for vomiting, for example kidney failure, liver failure, hyperthyroidism, or GI cancer. If all those problems are ruled out and your vet is concerned about potential IBD or IBS, I recommend submitting a blood sample to the GI lab at Texas A&M University for a functional GI test. This test can help determine if your cat is dealing with malabsorption and maldigestion, or a disease of the small intestine or pancreas.

Cause No. 7: Toxin Ingestion

Poisoning can also be the cause of acute vomiting in kitties. It's rare, but it happens. If you have a cat who is otherwise healthy, especially an indoor-outdoor kitty, and he suddenly starts vomiting, you should be concerned he has ingested something toxic.

Even if your cat is indoors only, unfortunately, many types of houseplants are poisonous for cats — and many cats like to sample houseplants. It's important to make sure you're not bringing anything into your home that could potentially poison your feline family member.

It's important to note that since cats are designed to eat fresh food, they'll nibble on anything fresh in your house if they're not provided a fresh food diet. Since felines don't have a biological requirement for plants, it's a good bet most house-plant sampling cats are trying to supplement a processed diet with living foods.

If you have kitties who like to snack on your houseplants, I recommend providing them roughage that is more palatable and safer. You can do this in the form of cat grass, which is wheatgrass, or by offering fresh sunflower sprouts.

In addition, any pesticides, herbicides, or household cleaners that are stamped "call poison control" need to be safely stored out of the way. You should assume any cleaner you're using in your house will ultimately be ingested by your cat, because kitties lay on surfaces, and they're fastidious groomers.

All your household cleaners should be cat friendly. I can't emphasize enough that if you are still using traditional toxic household cleaners, if you have cats, one of the best gifts you can give them is to switch to nontoxic household cleaners.

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