Vomiting in cats: what's normal and what's not
Vomiting – every cat does it. But how much is normal and when is it serious?
You've probably seen or heard your cat having a spew... or you've stepped in a little pile of second-hand cat food/furball. If this happens occasionally and your cat is otherwise fine, it's probably 'normal'. Frequent vomiting isn't normal, but it's not necessarily serious either. When we're presented with a vomiting cat, the first thing we need to work out is if the problem is acute and self-limiting or needs more thorough investigation and treatment.
So, let's get to know vomiting... which sounds gross but is actually pretty interesting.
What is vomiting?
Okay, this sounds like a silly question. But can you tell the difference between vomiting, regurgitation or productive coughing? There are very different causes and treatments for each of these processes.
Vomiting is an active process that is triggered by something stimulating part of the brain called the vomiting centre. The vomiting centre can be triggered by:
- nerves – for example, if part of the gut is stretched (say due to an obstruction) messages travel from the gut wall via various nerves to the brain and stimulate the vomiting centre to induce vomiting and relieve the stretching. Not all the nerves that stimulate the vomiting centre come from the gut
- things in the bloodstream – such as drugs and toxins, which can have come from the outside (eg eaten or through the skin/lungs) or from the inside (eg kidney or liver failure causing build up of toxins)
Once the vomiting centre is stimulated, the vomiting reflex is triggered. This involves a sequence of events including dilation/relaxation of upper parts of the gastrointestinal tract (GIT) and forceful contractions of the lower parts and abdominal muscles. The process often starts with retching (rhythmic inspiratory movements against a closed throat), which prevents stuff coming out until enough pressure has built up. The majority of what is expelled comes from the stomach.
If you're really interested in how it all works, there is a YouTube video I really like. It talks about vomiting in people, but the mechanism is exactly same in cats and dogs.
And just so you can tell the difference...
Regurgitation is a passive process where food or liquid comes up from the pharynx or oesophagus. The vomiting centre is not involved and there are no forceful contractions.
Productive coughing is usually bringing up material from the airways. In some cases, food particles can have got into the airways triggering the coughing. And in some other cases, the coughing can trigger retching and vomiting.
What causes vomiting?
Oh, where to start?! There are so many potential causes of vomiting that it might be easier to make some broad categories (see the very long list below). Fortunately, in most cases, we are able to narrow this list down based on history and physical examination. But further testing is often needed to get to an actual diagnosis. That said, for acute vomiting in an otherwise well cat, we will often use simple symptomatic therapy because the cause is unlikely to be serious and will resolve on it's own.
Here are (some) of the causes of vomiting, listed in categories.
Gastric vomiting may be due to:
- gastritis (inflammation of the stomach wall), which can be due to infection, irritation, immune-mediated disease, medications
- foreign bodies
- outflow obstruction
- motility disorders
Intestinal causes of vomiting include:
- inflammatory bowel disease
- foreign bodies
- intussusception (where the bowel telescopes in on itself)
- enteritis (inflammation of the intestinal wall), which can be due to infection, irritation, medications
- enteropathy (non-specific disease of the intestinal wall)
- functional disorders
- constipation (which has it's own huge list of causes!)
Pancreatic causes of vomiting include:
- pancreatic cancer
Liver and gallbladder
Liver and gallbladder (hepatobiliary) causes of vomiting include:
- hepatatitis, cholangitis (gallbladder inflammation), which can be due to infection, immune-mediated disease, toxins
- biliary obstruction
The main sort of splenic disease that causes vomiting in cats is a mast cell tumour (note these aren't always only in the spleen).
The conditions of the urinary and genital tracts that can cause vomiting include:
- nephritis (kidney inflammation)
- pyelonephritis (kidney infection)
- nephrolithiasis (kidney stones)
- urinary obstruction
- pyometra (uterine infection)
- prostatitic disease
People often look at me quizzically when I mention the peritoneum. So here's a quick explanation. First, the peritoneum is not the perineum (the area between the anus and the genitals). The peritoneum is a membrane that covers the inner wall of the abdomen and most of the abdominal organs – it acts to prevent friction and hold things in their proper location. The peritoneum consists of two main parts: the omentum, which hangs in front of the stomach and intestine; and the mesentery, which attaches the small intestine and most the large intestine to the abdominal wall under the backbone. Both contain blood vessels, nerves, lymph nodes, fat, elastic fibres for stretching and collagen fibres for strength.
Conditions of the peritoneum that can cause vomiting include:
- peritonitis (inflammation of the peritoneum), which may be caused by things like a bowel perforation, a penetrating abdominal wound, a leaking gallbladder, a leaking urinary tract
- torsion or twisting of the mesentery
Metabolic and hormonal
Metabolic and hormonal causes of vomiting include:
- uraemia (an excess of urea and creatinine in blood stream due to kidney failure)
- diabetic ketoacidosis (an excess of ketones/acid in the blood stream due to uncontrolled diabetes)
- hyperthryroidism (too much thyroid hormone)
- hepatic encephalopathy (a brain condition that occurs when the liver isn't able to detoxify the blood properly)
- hypercalcaemia (too much calcium in the blood stream due to cancer or toxicity)
- septicaemia (bacteria in the blood stream)
Some of the more common infectious causes of vomiting include:
- feline panleukopaenia (cat parvo)
- virulent calicivirus (one of the components of cat flu)
Drugs and toxins
Almost all drugs and toxins have the potential to cause vomiting. Ones that we quickly rule out include:
- non-steroidal anti-inflammatories
- human medications
Dietary causes of vomiting include:
- eating rotten foods
- sudden change in diet
- food intolerance or allergy
Neurological causes of vomiting include:
- vestibular disease (causes 'motion sickness')
- encephalitis (brain inflammation)
- head trauma
- strong smells
Phew, that's over! Sorry about such a long list of stuff but lots of people ask 'Why is my cat vomiting?' expecting a simple answer... and as you can now see, that isn't always so easy to give.
How do we approach vomiting?
As mentioned earlier, the first thing we need to do is decide if your cat has acute (ie present less than 2–3 days) vomiting that is likely to settle down on its own, or if your cat has more severe or chronic vomiting.
If your cat has acute vomiting and is not systemically unwell, then simple treatment such as small bland feeds and/or symptomatic treatment (such as an anti-vomiting injection) is usually all that's needed.
If your cat has been vomiting regularly for over a week or if the vomiting is associated with lethargy, weakness, abdominal pain or there is blood in the vomit and/or bloody diarrhoea then we'll recommend looking for an underlying cause so that we can provide specific treatment.
A detailed history and a thorough physical examination can usually narrow down that long list of potential causes. Making a definitive diagnosis usually requires some form of investigation. For example, if we feel a lump in the abdomen, we can narrow the list down to a foreign body, tumour, intussusception or maybe constipation (depending on where the lump is). But to determine what the lump is we would need to perform further procedures such as X-ray, ultrasound, endoscope or surgical exploration. If the abdomen feels normal, we usually start with blood tests looking for metabolic or hormonal causes such as kidney failure and hyperthyroidism (both very common in older cats).
In some cases, we may perform multiple tests such as bloods, ultrasound, endoscope and X-ray and still not have a definitive diagnosis. Sometimes the only way to get that is with surgical biopsy. For example, some cancers can invade the intestines (eg lymphoma) and show up only as diffuse thickening of the bowel wall. This can appear the same as inflammatory bowel disease. The way to tell the difference is by sending a piece of intestine to a pathologist who can look at the cells and make a diagnosis.
For a range of reasons, people may choose not to pursue diagnostics, particularly when it comes to invasive options. That's okay too – we're life trained as well as textbook trained, so we can do other things like use response to treatment as a way of getting to a diagnosis.
How is vomiting treated?
Obviously, treatment will largely depend on cause: foreign bodies are usually treated surgically; cancers might be surgically removed or treated with chemotherapy; inflammatory bowel disease may need steroids. Common therapies for vomiting cats include the following.
Lots of cats with chronic vomiting respond well to a change of diet, so it's often well worth trying if your cat is otherwise well.
Some cats do better switching from dry to wet (or occasionally the other way) or by changing the food to a sensitivity or hypoallergenic type.
These are called antiemetics. There are several different types and they work on different receptors in the vomiting centre (and another related bit of the brain called the chemoreceptor trigger zone). The most common one we use is maropitant (Cerenia®).
We usually only use antiemetics for acute vomiting and for symptom control in severe vomiting while we're looking for or treating the underlying cause. We don't usually use anti-vomiting medications where we suspect toxin ingestion (we don't want to keep the toxin in), foreign bodies or if we have severe liver disease (because the liver may not be able to metabolise the medication).
Vomiting can cause dehydration, electrolyte and acid-base disturbances. Intravenous (IV) fluids is used to correct these problems, especially for cats that can't or won't take in oral fluids. Most of the time, IV fluids are used short-term to support cats with acute, severe vomiting.
These are useful for cases of gastritis and gastric ulceration. Medications considered to 'protect' the stomach include:
- sucralfate (Carafate®), which adheres to damaged areas of the oesophagus and stomach creating a physical barrier against gastric acid, and also binds to toxins and carries them through the gut
- antacid medications (eg ranitidine, famotidine, omeprazole, pantoprazole), which make the gastric acid less acidic and therefore less irritant to eroded or ulcerated areas of the stomach and oesophagus
Giving analgesics to cats with painful abdomens due to conditions such as pancreatitis or peritonitis can help with vomiting.
Antibiotics are used to treat infections that might be causing vomiting such as kidney infections (pyelonephritis), Helicobacter gastritis or bacterial cholangiohepatitis. These conditions require diagnostic testing to diagnose.