Please note, excess stomach acid is not the same thing as metabolic acidosis .
Causes of Nausea, Vomiting and Loss of Appetite Back to Page Index
Unfortunately, there are a large number of possible causes of nausea, vomiting and loss of appetite in CKD cats. It can therefore be confusing trying to decide what might be the cause in your cat's case. To help you narrow it down, I would scan through the list of symptoms on the Index of Symptoms and Treatments page to see if any of them look familiar.Alternatively, the list below outlines some of the possible causes of nausea, vomiting and loss of appetite. If you already know that your cat has a particular problem, say, high phosphorus levels, you can click on the appropriate link where you will find more information on other symptoms associated with that condition, which may help you narrow down the cause:
pancreatitis commonly causes vomiting
Ask your vet to rule out any of these causes or to treat them if they are present. Treating any that are present should not only stop the vomiting and appetite loss and help your cat feel more comfortable, it may in some cases (e.g. controlling high phosphorus levels) also help slow the progression of the CKD.
Toxins, Including Excess Stomach Acid
Even if you rule out or treat the above causes, your cat may still continue to have problems with vomiting, nausea and appetite loss, so the chances are you need to read this page even if your cat has some of the above problems too. Take a look at the list of symptoms below and see if they sound familiar - most people find they do.
In such cases, the problem may be caused by toxins. As the kidneys gradually lose their ability to regulate and remove waste products effectively, these waste products build up in the blood. This is called uraemia and can make a cat feel very unwell. Y ou can read more about uraemia here.
Although BUN is not itself a toxin, there is a correlation between it and other toxins which are less easy to measure. Therefore,
the higher your cat's BUN or urea level, the higher the overall toxin load will be, and the more likely it is that s/he will feel sick and vomit.
CKD cats may also have problems with excess stomach acid. Gastrin is a gastrointestinal hormone which stimulates the secretion of gastric acid, which helps the stomach digest food. The kidneys are responsible for the excretion of gastrin, but in CKD this function may not work so well, resulting in the gastrin remaining in the stomach and potentially stimulating the production of too much gastric acid. Feline CKD: Current therapies - what is achievable? (2013) Korman R & White J Journal of Feline Medicine and Surgery 15(S1) pp29–44 says "Gastrin is excreted by the kidneys and the concentration increases with CKD progression, increasing gastric acidity and the risk of ulceration." Excess stomach acid can make a cat feel very unwell. In severe cases stomach ulcers may develop, which may cause gastrointestinal bleeding.
A more recent study, Relationship among serum creatinine, serum gastrin, calcium-phosphorus product, and uremic gastropathy in cats with chronic kidney disease (2014) McLeland SM, Lunn KF, Duncan CG, Refsal KR & Quimby JM Journal of Veterinary Internal Medicine 28(3) pp827-37 compared CKD cats with healthy cats. They found that 84% of the CKD cats exhibited loss of appetite and 45% exhibited vomiting, but although the CKD cats did have higher levels of gastrin compared to the healthy cats, there did not appear to be any correlation with the severity of the CKD. The study states "Gastrointestinal signs in these animals may not necessarily be the result of gastric lesions such as gastric ulceration and inflammation, but perhaps the consequence of circulating uremic toxins interacting with the chemoreceptor trigger zone in the brain."
Chronic use of maropitant for the management of vomiting and inappetance in cats with chronic kidney disease: a blinded placebo-controlled clinical trial (2014) Quimby JM, Brock WT, Moses K, Bolotin D, Patricelli K Journal of Feline Medicine & Surgery 21. pii: 1098612X14555441. [Epub ahead of print] says "Interestingly, the exact mechanism of why CKD cats suffer from decreased appetite and vomiting is not currently known. Gastrin hormone that is responsible for stomach acid production is elevated in CKD cats; however, increased stomach acidity and stomach ulceration have not been document [sic] in humans or cats with CKD. It is suspected that CKD cats have an increase in toxins referred to as uremic toxins that trigger the vomiting center (chemoreceptor trigger zone of the area postrema) in their brains."
Whatever the cause, a CKD cat who exhibits the symptoms listed below needs help. Generally speaking, these will be cats with creatinine over 3 mg/dl (US) or 265 mmol/L (international) (IRIS stages 3 or 4). Feline CKD: Current therapies - what is achievable? (2013) Korman R & White J Journal of Feline Medicine and Surgery 15(S1) pp29–44 says "Cats in CKD stages 3-4 often demonstrate gastrointestinal signs of uraemia (eg, inappetance, nausea, vomiting, stomatitis, gastrointestinal ulceration, diarrhoea, colitis) and addressing these may improve quality of life."
If your cat has relatively low kidney bloodwork values (creatinine of 2.5-3 mg/dl US, 200-300 mmol/L international) but nevertheless seems to vomit a lot, it might possibly be because of CKD-related toxins, but I would also ask your vet to rule out pancreatitis.
There is no test as such for toxins, but these are some of the symptoms you might see (though some of these may also be due to other causes, as mentioned under each category):