Yellow vomit in cats: what is bilious vomiting syndrome?
Introduction
Lots of owners tend to think that yellow vomit in cats is due to liver disease. This is probably because certain liver diseases course with jaundice and so the colour yellow is commonly associated with liver problems. However, not all liver diseases cause yellow vomit, nor is yellow vomit in cats always caused by liver disease. In fact, the differential diagnosis for a cat presenting at consultation with yellow vomit can be quite extensive.
A further possibility to consider is the presence of bilious vomiting syndrome, which should still be viewed as a potential differential diagnosis even though it is considerably less common in cats than dogs.1
What is bilious vomiting syndrome (BVS)?
BVS is a clinical entity that mainly courses with intermittent bilious vomiting, generally in the morning and after prolonged periods of fasting, in animals that do not usually present any significant clinical abnormalities.1,2
It is believed that BVS is due to impaired digestive motility, so it is more likely to affect animals with disorders associated with impaired gastric emptying (obstructions, gastritis, gastric ulcers, neoplasms, inflammatory bowel disease or pancreatitis, for example) and those fed only once a day.
The pyloric valve allows bile reflux to pass from the duodenum to the gastric lumen, resulting in irritation of the stomach lining and vomiting. 1,2
Yellow vomit in cats: diagnostic assessment
The first step is to confirm that the animal is actually vomiting rather than regurgitating or coughing. Although the presence of bile generally rules out the possibility of regurgitation, it is still a good idea to confirm this point.3 So it helps to show the owners a video illustrating the difference between the two processes, or you could ask them to record an episode at home.
The next step is to take a thorough anamnesis and perform a physical examination for indications about the origin of the problem:
- It is important to try to establish how often vomiting occurs and whether there is a relationship between food intake and time until the cat vomits.
- Vomiting can have a broad range of aetiologies, including systemic disorders (sepsis or multiorgan failure), metabolic disorders (uraemia or liver failure), endocrinopathies (hyperthyroidism), gastrointestinal disorders (inflammatory bowel disease, neoplasms, obstructions), pancreatitis and hepatobiliary diseases.3,4
- Given this broad differential, the diagnostic approach should mainly focus on the acute or chronic nature of vomiting and the animal’s clinical condition:
- In most acute cases, especially if there are no significant clinical abnormalities, vomiting is usually self-limiting. Therefore, if the cat is in good clinical condition, conservative management is a feasible option, assessing the animal’s progress after 24 hours. However, given the slightest suspicion of foreign body ingestion, it is prudent to perform abdominal X-rays even on clinically stable patients.
- In cats with chronic vomiting or with more severe clinical signs, by contrast, the initial indication is to collect blood, urine and stool samples for haematology, blood chemistry (including electrolytes), urinalysis and stool analysis, as well as serology for feline leukaemia and immunodeficiency viruses and T4 testing (especially in cats over 5 years old).
- If these tests do not reveal the cause of the vomiting, an abdominal ultrasound and fPLI, dynamic bile acid and ACTH stimulation tests are indicated, leaving digestive endoscopy as the final method used to help determine the origin.3,4
BVS is diagnosed by exclusion. So, in most cases, the results of the above tests are normal.1 Therefore, if the initial assessment does not indicate a serious disease and the cat’s general condition is satisfactory, a therapeutic trial is an option before carrying out certain tests. BVS management using this approach is based on increasing the number of daily meals (3–6 meals) and minimising the time the cat spends without eating at night. Semi-liquid, low-fat and low-fibre diets are recommended to encourage gastric emptying. If dietary management is ineffective, consider adding prokinetics and/or omeprazole.1
Conclusions
There are multiple reasons why a cat may develop bilious vomiting. As such, it is important to explain to owners that while some cases of vomiting are associated with liver disease, in most cases it will have another cause. The diagnostic protocol must be adapted to the patient’s clinical condition and should assess the utility of conducting a therapeutic trial.
