Chronic vomiting is a common clinical sign seen in cats, a lot of owners will report their cat vomits occasionally – which can be normal. However a cat vomiting often may warrant investigations. Depending on the age and breed of your cat, a number of diagnoses will be possible, including food allergies, inflammatory bowel disease and gastritis. Vomiting is a non- specific sign and can also be caused by non- gastrointestinal diseases such as kidney and liver disease. Because vomiting has such a wide range of causes, often further investigations such as blood work and imaging is often needed to come to a diagnosis. A condition called “pyloric stenosis” became a more popular diagnosis for chronic vomiting, with most literature describing this condition being published in the 1970s. 

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What is pyloric stenosis?

The stomach is made up of the cardia, where the oesophagus meets the stomach, the fundus, the body and the pylorus. The pylorus is the last part of the stomach before food exits into the first part of the small intestines, the duodenum. Pyloric stenosis describes both a congenital (a condition an animal is born with) and an acquired condition in cats; where the pylorus is too narrow to function effectively and allow food through as it should. This leads to delayed gastric emptying which is associated with clinical signs like chronic vomiting. Occasionally leading to secondary issues such as oesophagitis (Pyloric stenosis in cats (felis) 2023) as well as abdominal pain (Preibisz et al., 2022). Although this is a relatively rare condition, and is rarely described in veterinary literature, there is some evidence that Siamese cats are more predisposed to this condition (Twaddle, 1970 – yes, really! – Ed.)

How is it diagnosed?

Pyloric stenosis was previously diagnosed by demonstrating delayed gastric emptying; this was done through contrast radiography or ultrasonography, proving a full stomach several hours after feeding (Pearson et al., 1974). More recent studies however use more modern diagnostic tools to investigate this condition, endoscopy allowing visualisation of the stomach as well as investigating if the endoscope could be passed through the pylorus, if it couldn’t be the cat was considered to have pyloric stenosis (Freiche et al., 2021). This is assuming other more common causes of gastric emptying have been ruled out, such as a foreign body or a mass. 

How is it treated?

Pyloric stenosis has been treated previously with a surgical procedure to increase the size of the pylorus, called a pyloroplasty (Freiche et al., 2021) (Twaddle, 1970). Supportive treatment includes treatment of symptoms and supportive treatment, such as intravenous fluid therapy, anti- emetics and gastroprotectants such as lansoprazole (Preibisz et al., 2022)

So why do we see it less now?

A general reason diagnoses go in and out of favour is the ability to prove or disprove a diagnosis. First opinion veterinary clinics rarely had diagnostic tools such as contrast radiography, fluoroscopy and endoscopy two or three decades ago; this meant that definitively diagnosing complex conditions such as pyloric stenosis was rarely done. Without this option for contrast imaging or advanced imaging a presumptive diagnosis of pyloric stenosis may have been made, therefore it is likely that many cats diagnosed with this were suffering with different conditions causing gastric motility issues. 

With the wider availability of these diagnostic tools, as well as referral centres with advanced diagnostic imaging options such as CT, a definitive diagnosis and underlying predisposing factors are more likely to be discovered. Gastric emptying as a way of diagnosing pyloric stenosis was also often previously used, with further research suggesting that hospitalised patients have reduced gastric emptying in a hospital setting, compared to the same patient in their home environment. This may have also caused an excess of diagnoses of pyloric stenosis, as this is a disease of reduced gastric emptying. (Warrit et al., 2017)

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