A healthy cat should never throw up. Throwing up is the forceful expulsion of stomach contents, and can be due to a multitude of causes. Usually, this mechanism is intended to remove the contents of the stomach when they don’t agree with the cat or prevent further digestion. There are a lot of myths that claim when a cat throws up, it’s "purging", or that "cats throw up from time to time to stay healthy". However, the truth is that even if it’s a mild and isolated event, it’s always because something has gone wrong. We can divide vomiting into two groups: acute and chronic.
This type of vomiting happens suddenly, in a short period of time, and is generally more frequent and produces more sick. The cat often loses its appetite, is apathetic, and can become dehydrated if it’s not drinking and holding down water. This may turn into a medical emergency. The most common causes of acute vomiting are usually acute gastritis due to the ingestion of bad food, toxic or irritating substances, pancreatitis, or foreign bodies that produce damage to the stomach's mucous membrane or that produce partial or complete gastric or intestinal obstruction. Among these foreign bodies, it's common to find hairballs, also known as bezoars, that are produced when cats groom themselves. Also, if cats aren’t regularly supplemented with laxative products to prevent the formation of hairballs (e.g. with a malt gel ), they can accumulate in the stomach and intestines, leading to bowel obstruction. When a cat shows symptoms of acute vomiting, you should never "wait and see", as it’s in danger of dehydration or liver failure, which can be very serious. Additionally, we’d be ignoring what is ultimately causing the vomiting, which also needs to be treated. Before waiting or applying home remedies, it’s best to go to the vet as soon as possible.
This is when cats vomit regularly and may lose weight, although they appear to be healthy and have a good appetite. To many owners, this seems normal, and it’s often these owners who relate the vomiting to "purging". However, this vomiting can be due to chronic pancreatitis, chronic intestinal or gastric diseases, chronic kidney disease, hyperthyroidism, viral diseases, liver diseases, or even tumours. Therefore, cases of chronic vomiting should also always be assessed by a vet.
When a cat is throwing up, before going to the vet, it’s always good to gather some information about your cat’s behaviour. For example, how often it’s vomiting, if its sick is made up of food or just saliva, and how much it’s vomiting each time. You should also carefully inspect the cat’s litter box to check if it’s urinating a normal amount or less frequently (which could be a sign of dehydration), in which case clumping sand can help you to quantify this.
Finally, it’s important to check if your cat’s stool is normal or if it’s suffering form diarrhoea. All this information will be useful for the vet.