Mouth Problems

Gastro-Intestinal Problems, Including Gastro-Intestinal Bleeding and Diarrhoea

Other Uraemic Problems

Vomiting, Nausea and Stomach Acid



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What Happens in CKD?

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Nausea, Vomiting, Appetite Loss and Excess Stomach Acid

Maintaining Hydration

The Importance of Phosphorus Control

All About Hypertension

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Alphabetical List of Symptoms and Treatments

Fluid and Urinary  Imbalances (Dehydration, Overhydration and Urinary Issues)

Waste Product Regulation Imbalances (Vomiting, Appetite Loss, Excess Stomach Acid, Gastro-intestinal Problems, Mouth Ulcers Etc.)

Phosphorus and Calcium Imbalances

Miscellaneous Symptoms (Pain, Hiding Etc.)



Blood Chemistry: Kidney Function, Potassium, Other Tests (ALT, Amylase, (Cholesterol, Etc.)

Calcium, Phosphorus, Parathyroid Hormone (PTH) and Secondary Hyperparathyroidism

Complete Blood Count (CBC): Red and White Blood Cells: Anaemia and Infection

Urinalysis (Urine Tests)

Other Tests: Ultrasound, Biopsy, X-rays etc.

Renomegaly (Enlarged Kidneys)

Which Tests to Have and Frequency of Testing

Factors that Affect Test Results

Normal Ranges

International and US Measuring Systems



Which Treatments are Essential

Fluid and Urinary Issues (Fluid Retention, Infections, Incontinence, Proteinuria)

Waste Product Regulation (Mouth Ulcers, GI Bleeding, Antioxidants, Adsorbents, Azodyl, Astro's CRF Oil)

Phosphorus, Calcium and Secondary Hyperparathyroidism (Calcitriol)

Miscellaneous Treatments: Stem Cell Transplants, ACE Inhibitors - Fortekor, Steroids, Kidney Transplants)

Antibiotics and Painkillers

Holistic Treatments (Including Slippery Elm Bark)

ESAs (Aranesp, Epogen etc.) for Severe Anaemia

General Health Issues in a CKD Cat: Fleas, Arthritis, Dementia, Vaccinations

Tips on Medicating Your Cat

Obtaining Supplies Cheaply in the UK, USA and Canada

Working with Your Vet and Recordkeeping



Nutritional Requirements of CKD Cats

The B Vitamins (Including Methylcobalamin)

What to Feed (and What to Avoid)

Persuading Your Cat to Eat

Food Data Tables

USA Canned Food Data

USA Dry Food Data

USA Cat Food Manufacturers

UK Canned Food Data

UK Dry Food Data

UK Cat Food Manufacturers

2007 Food Recall USA



Intravenous Fluids

Subcutaneous Fluids

Tips on Giving Subcutaneous Fluids

How to Give Subcutaneous Fluids with a Giving Set

How to Give Subcutaneous Fluids with a Syringe

Subcutaneous Fluids - Winning Your Vet's Support




Heart Problems



Polycystic Kidney Disease (PKD)


Dental Problems









The Final Hours

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Coping with Your Loss



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Canine Kidney Disease

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Home > Symptoms > Waste Products Regulation



  • 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.

  • In addition, CKD cats may have problems with excess stomach acid. Gastrin is a gastro-intestinal 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 stimulating the production of too much gastric acid.

  • This excess stomach acid can also make a cat feel very unwell. Generally speaking, cats with creatinine over 265 (US: 3) will need help controlling stomach acid.

Pet Place has some information about gastric motility problems in cats (you don't need to register to read the article, just click on the Close This Window link at the bottom of the registration pop-up).


Mouth Problems                                                                                                   Back to Page Index

Bad Breath

The high levels of urea seen in CKD cats are released into saliva. An enzyme in the bacteria in the mouth called urease interacts with the urea and produces a very strong and distinctive odour. It is hard to describe the aroma, though once smelled, never forgotten. It is sometimes described as being an ammonia smell (like bleach) but it may smell more like urine (ammonia is a constituent of urine), though neither description really captures the smell. This smell will be particularly noticeable if the cat crashes. If your cat's breath smells more like nail polish remover, this may indicate diabetes.


Mouth Ulcers

If the cat is very poorly or in a more advanced stage of renal failure, the toxins produced by the body can cause ulceration of the gums, which occurs when the uraemic waste is converted by the bacteria in the mouth into ammonia (hence the smell of the cat's breath being described as ammonia-like above). You may see ulcers in the cat's mouth if you look inside, or in severe cases your cat may vomit blood (which may also be a sign of bleeding from further down the gastro-intestinal tract). You may also see drooling. Some cats paw at the mouth (which can also be a sign of dental problems).


Mouth ulcers are painful for the cat and often lead to a lack of appetite, or, even more distressingly, a desire to eat coupled with an inability to do so - the cat may approach the food bowl and sniff the food, then walk away. Mouth ulcers may also be a sign of metabolic acidosis.


Check inside your cat's mouth regularly for inflamed gums or ulceration or ask your vet to do so. I am sometimes asked what mouth ulcers look like. They are usually a small area of white or yellow, sore-looking skin with a thin red ring around it. Long Beach Animal Hospital has a photo of mouth ulcers in a CKD cat. Starbrite Dental has a couple of photos of human mouth ulcers.


Teeth Grinding

Cats who grind their teeth may have excess stomach acid. Dental problems are another possible cause. It may also be a sign of dehydration. Very occasionally, this might be a sign of "rubber jaw", caused by a condition related to the CKD called secondary hyperparathyroidism.


Animal Dental Center of Milwaukee and Oshkosh discusses the various causes of teeth grinding in cats.

Youtube has a video of a cat grinding his/her teeth.



Drooling cats may have excess stomach acid. Dental problems or mouth ulcers may also  cause drooling. Manhattan Cat Specialists have more information about drooling.


Pawing at the Mouth

The most common reason for this is dental problems. Occasionally it is a sign of mouth ulcers.


Gastro-Intestinal Problems                                                                                Back to Page Index

Gastro-Intestinal Bleeding (Dark Stools)

If the uraemia is particularly bad, the cat may develop gastro-intestinal bleeding. This is not easily detectable, but dark stools are one possible sign, as is vomiting blood. Occasionally, however, dark stools are caused by iron supplements.


If gastro-intestinal bleeding remains untreated, anaemia may result. If you suspect gastro-intestinal bleeding, you should take a stool sample to your vet for occult blood testing (when I did this for Ollie, I was the first client who had ever requested this test; but it was positive). You can also buy the EZ Detect test from pharmacies, which tests for blood in the stool or urine (this is a human test but can also be used for cats). CKD cats with this problem do not normally need to be treated in hospital.


Pet Place has some information about blood in stool (melena). You don't need to register to read the article, just click on the Close This Window link at the bottom of the registration pop-up.



Diarrhoea may sometimes be seen in CKD cats secondary to the CKD. There are a number of other different causes of diarrhoea, including hyperthyroidism, inflammatory bowel disease (IBD), malabsorption problems, and parasites, so if the diarrhoea lasts longer than a day or so, you must see your vet, both to ensure your cat is OK (diarrhoea may cause or worsen dehydration) and for a proper diagnosis.


Possible causes of diarrhoea in a CKD cat include:

  • a sudden change of food, perhaps to a prescription diet. It is better for a cat's digestive system if a new food is introduced gradually - mix some of the new food with the old and gradually increase the amount of the new food in the mix over a period of several days.

  • food intolerance. Because the goal is to reduce protein levels, some CKD prescription foods in particular may have relatively high levels of carbohydrates, and some cats who are used to a higher protein diet may find these harder to process. Introducing the new food gradually may help, but some cats are simply grain-intolerant.

  • cats taking antibiotics may develop diarrhoea. Pet MD discusses this. If you think this might be the cause, contact your vet and ask if you can switch to a different antibiotic. Please do not just stop the antibiotic, however, or the infection may return with a vengeance.

  • too much lactulose or MiraLAX, given to treat constipation, may cause the opposite problem of diarrhoea. It is better to start lactulose at a low level and increase as necessary.

  • sometimes people think their cat has really runny diarrhoea, but in actual fact, the cat is constipated and the runny liquid is all that can squeeze out round the solid stool. This is known as "overflow incontinence". So do be aware of this possibility, particularly if there is only a small amount of liquid faeces.

  • Pet Education and Drs Foster and Smith both mention that potassium supplements may cause diarrhoea.

  • nephrotic syndrome, though this is actually relatively rare in cats.

  • another disease called Inflammatory Bowel Disease (IBD) may cause diarrhoea. This is covered in Harpsie's website.

  • hyperthyroidism may also cause diarrhoea in some cats.

Idexx Laboratories offer new tests for cases of diarrhoea where a pathogen is thought to be involved.

Diagnostic and therapeutic approach to cats with chronic diarrhea (2001), Marks S is a paper presented to the World Small Animal Veterinary Association 2001 World Congress.

Washington State University College of Veterinary Medicine discusses the causes of diarrhoea in dogs and cats.

Vet Info discusses the problems of ascertaining the cause of chronic diarrhoea.

Pets Canada describes the various types of stool that may be seen when a cat has diarrhoea.

Vet 4 Petz describes the different types of diarrhoea in cats.

Newman Veterinary discusses causes of diarrhoea.


Other Uraemic (Toxin Build Up) Problems                                                      Back to Page Index

Body Odour

Some CKD cats have a distinctive aroma, which is caused by the levels of toxins in the body. It is similar to the bad breath aroma. You may notice an increase in this aroma or it may develop for the first time if your cat's bloodwork is worsening. In some cases, you may first notice this smell when your cat crashes. Thomas developed this smell seemingly overnight when he crashed, but after treatment it gradually disappeared. 



If allergies are ruled out, this can be a uraemic itch, i.e. caused by the levels of toxins in the blood. Pruritus in certain internal diseases (2007) Yonnova D Hippokratia 11(2) pp67-71 mentions that itching occurs in about 15% of uraemic human patients, so if your cat is scratching a lot or grooming excessively, consider this possibility. Itching is fairly common in cats with high phosphorus levels, particularly if the high phosphorus levels go untreated, resulting in secondary hyperparathyroidism. Alternatively itching may indicate a Vitamin B deficiency or be a sign of an essential fatty acids deficiency. Occasionally itching can be a sign of liver problems; if this is the case, your cat's bloodwork should show elevated liver values.


If your cat actually pulls out fur rather than merely scratching, this may indicate hyperthyroidism. Itching, particularly on the face, may also be a side effect of the medication used to treat hyperthyroidism.


Twitching, Trembling or Shaking

This can be caused by the toxin levels, and if so, it should improve as toxins are controlled. It may also be related to potassium levels, or caused by high phosphorus levels, high blood pressure, calcium imbalances (especially head twitching), hyperthyroidism or Vitamin B deficiency. If your cat only twitches while you are giving fluids, it is probably caused by either the type of fluid used or by giving cold (room temperature) fluids.


Pharaoh's Shakes is a video showing a CKD cat twitching.

Pet MD mentions that twitching may be caused by kidney disease.



Occasionally, if toxin levels are really high (and particularly if a cat is in The Final Hours), a CKD cat may have seizures. In such cases, reducing toxin levels is essential in order to avoid permanent damage to the brain; but this may not be possible if the cat is in his/her final hours.


Seizures may take a number of different forms. There may be the classic jerking and loss of consciousness, but being "spaced out" or mentally absent or staring into space may also be a type of seizure. Harpsie's website has more information on what seizures may look like.


Seizures may also be caused by high potassium levels, calcium imbalances, metabolic acidosis or by high blood pressure. The use of Metoclopramide (Reglan) for stomach problems or Advantage for fleas may lower the seizure threshold. Other possible causes of seizures include epilepsy or a brain tumour, but the causes mentioned above are far more likely in a CKD cat and should therefore be considered first.


Howling (Particularly at Night)

This is sometimes the result of toxin levels in the blood. However, it may also have other causes such as deafness, hyperthyroidism, high blood pressure or occasionally just old age and possibly cognitive dysfunction (senility). 


Certain medications such as periactin (Cyproheptadine), an appetite stimulant, or steroids can make a cat become vocal. Metoclopramide (Reglan), used for stomach problems, may also have this effect.


I would recommend always having blood pressure checked in a howling cat.


Vomiting, Nausea and Excess Stomach Acid                                                Back to Page Index

These problems are so common in CKD cats that there is a page devoted to them. Symptoms covered there include:

Treatment Options                                                                                                  Back to Page Index


It is possible to treat all of the above symptoms, in many cases effectively, and details can be found in the Treatments section.




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This page last updated: 18 September 2013

Links on this page last checked: 27 March 2012