Vomiting and Diarrhoea

It is very common to see cats or dogs brought in with vomiting, diarrhoea, or both. We can look at some of the common causes and how to treat and also how to prevent them from recurring.


Food starts off in the MOUTH and is swallowed, passing down the OESOPHAGUS into the STOMACH. In here, it is mixed with the stomach acids which assist in the digestive process. It passed out into the SMALL INTESTINE, where secretions from the PANCREAS and LIVER help digestion and nutrients are absorbed. The food passes on into the LARGE INTESTINE, where further nutrients and water are absorbed, before the undigested food passes out as faeces.


The stomach produces a wave of muscle contraction, which carries food back up from the stomach to the mouth. It is important to distinguish this from regurgitation, which is where the food is brought back up immediately after swallowing, without reaching the stomach.


Faeces are passed out frequently, in a liquid form, due to inadequate water reabsorption, altered intestinal motility etc. If diarrhoea is of small intestine origin, there may be fairly frequent attempts to ‘go’, large volume passed, dark, tarry consistency etc. If it is of large intestine factors, there may be very frequent attempts to ‘go’, fresh red blood, jelly visible etc.



There are many potential causes, the most common being:

  • Gastroenteritis/colitis – inflammation of the stomach and intestines
  • Gastrointestinal infection
  • ‘Food poisoning’
  • Food allergies
  • Worms/parasites
  • Inflammatory/irritable bowel type syndromes

Less common causes include:

  • Foreign body
  • Growth/tumour
  • Intussusception (intestines ‘telescoping’ into each other)
  • Poisoning
  • Systemic disease e.g. liver/kidney, thyroid, pancreas problems 
  • A good history is very important



  • Is it vomiting only? Diarrhoea only? Both?
  • How long has it been happening?
  • What does the vomit or motion look like? Any blood, ‘jelly’, bile in it etc.?
  • How soon after eating?
  • Any pattern to it?
  • Are any in contact animals affected?
  • Any diet change, scavenging food etc.?
  • Are they vaccinated and wormed?

In many cases, we will try symptomatic treatment before any major investigations, as most cases will settle down very quickly.

Tests we may need to do include:

  • Faeces test – for worms, parasites, bacteria and to see which antibiotics are effective against them
  • Blood test – to check for liver, kidney, pancreatic function.
  • Radiographs (x-rays) – to check for foreign bodies, abnormal shape or size to any organs
  • Endoscope – a camera to look at the inside of the digestive tract (we do not have this facility here and this would need referral to a specialist)
  • Biopsy – to take samples from the digestive tract for analysis. This may be done by surgery or sometimes by endoscopy
  • Diet trial – feed a bland, low allergy diet to see if this is effective at stopping the vomiting and diarrhoea



Mild cases may sometimes be dealt with by ‘first aid’ treatment at home – however, if you are at all concerned, we strongly advise you to come for a check-up.

  • Withhold food for 24 hours, to give the digestive tract a chance to recover. Provide small amounts of fresh water little and often
  • Start feeding a small amount e.g. teaspoon of a bland diet – we can provide a specially designed (chicken and rice based) tinned food for this purpose, alternatively, home cooked chicken, white fish, pasta, rice, potatoes etc. can be used
  • Increase the amount and size of the portions over the next day or two and if all is OK, then gradually wean your pet back onto their normal diet

More serious cases can need additional treatment, which might include:

  • Drugs to alter motility – depending on the case, we may give a drug to speed up the intestines and stop vomiting, or we may give one to slow them down and allow more time to absorb nutrients and water
  • Drugs to ‘bind up’ and solidify the faeces, usually given as a syrup or suspension
  • Antibiotics – if there are signs of infection. However, there are normal bacteria in the intestines which help digestion and antibiotics can sometimes get rid of these too
  • Antacid drugs (H2 blockers) – due to their diet, cats and dogs rarely get acid/stomach ulcers, but antacids may be of use. There is also a paste to bind to and protect the stomach lining
  • Fluid therapy – mild cases can sometimes benefit from specially made up oral solutions, containing salts, sugars etc. More serious cases may need hospitalising and fluids given intravenously via a ‘drip’
  • Diet modification – feeding a low allergy food, possibly little and often, and possibly from a height may help. There is no one ideal food and it may be a case of ‘trial and error’
  • Anti-inflammatory drugs to reduce inflammation in the digestive tract.
  • Surgery – can be needed in such cases as foreign bodies, twisting of the intestines, intussusception, tumours etc.


Healthy dogs and cats can occasionally have an ‘upset tummy’ for a day or two and this then settles down; if your pet either has an on going case of vomiting /diarrhoea or is unwell please call the clinic for an appointment.