Fluid-Related Issues:


Overhydration and Sudden Weight Gain




Urinary Tract Related Issues:


Urinary Tract Infections (including D-Mannose)

Kidney Infections (Pyelonephritis)


Inappropriate Elimination




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Home > Treatments > Fluid and Urinary-Related Issues



  • Since one of the kidneys' functions is to regulate fluid levels in the body, problems in this area are common in CKD cats.

Regulation of Fluid Levels in the Body



Dehydration is a common problem in CKD cats. If CKD cats "crash" and are in crisis they are usually severely dehydrated and intravenous fluids (IV) at the vet's may be required for several days - Thomas had these twice and they were very effective.


Of course, ideally you do not want things ever to progress to this stage, so to avoid dehydration in the first place, fluids may be given under the skin at home (sub-cutaneous fluids). Fluid Therapy is so essential in the treatment of CKD that it has its own page. 


Dry Coat

This can be a sign of dehydration, so should improve once your cat's hydration is under control. Slippery elm bark is often used to control excess stomach acid and to help with mouth ulcers, but as a side effect it often improves the cat's coat.


Overhydration: Fluid Retention/Build-Up

Some CKD cats may develop problems with fluid retention. This is not uncommon in cats who are receiving too much fluid, either via IV or sub-Qs. Some vets say it is not possible to overhydrate a cat using sub-Qs, but believe me, I've heard of plenty. If your cat feels "squishy" when you stroke him or her, this may indicate fluid retention, in many cases caused by overhydration from excessive sub-Qs. The cat may also show loss of appetite, because the fluid may be pressing on the stomach causing a feeling of fullness. Overhydration may also cause hypertension. In such cases, you may find that reducing the amount or frequency of sub-Qs solves the problem; so speak to your vet about this. The Subcutaneous Fluids page has information on amounts and frequency of fluids. 


Sometimes fluid retention may become more serious, and in the worst cases may lead to or be caused by congestive heart failure. Fluid may collect:

  • in the lungs (pulmonary oedema)

  • around the lungs (pleural effusion)

  • in the abdomen (ascites).

If your cat has loss of appetite, appears to be gaining weight rapidly or suddenly, particularly if he/she also starts coughing and/or develops a nasal discharge, you need to see a vet quickly. If s/he starts breathing with the mouth open or has a limp, this is a medical emergency and you need to get to a vet as quickly as possible. Your vet will probably arrange an x-ray which will show clearly whether there is fluid in or around the lungs or abdomen. If there is a lot of fluid, they will arrange to remove it either manually via thoracentesis (if the fluid is pleural effusion, around the lungs) or by using a type of drug called diuretics.


Do not give sub-Qs to a cat exhibiting any of the above symptoms until you have spoken to your vet. You should also never give a cat sub-Qs until the fluids from the previous session have been absorbed. 


If your cat does exhibit these problems and you can afford it, I would recommend a visit to a feline cardiologist to discuss future treatment options for your cat. It may still be possible to give sub-Qs in the future if your cat needs them, but it is a careful balancing act between the needs of the kidneys and the needs of the heart.


If your cat is prone to overhydration, I would recommend weighing him or her daily, so you can be alert to possible problems. Remember, your cat will weigh more after being given fluids - 100ml is a little under 4 ounces.


Weight Gain

Most people are delighted when their CKD cat gains weight, and certainly if weight gain is slow and steady, this is good news. However, if your cat gains weight very quickly - I have heard of people who are delighted because their cat has gained 2 lbs in a week, a phenomenal rate of weight gain as a percentage of the average cat's size -  you need to investigate the cause. A sudden increase in weight, particularly if your cat is receiving sub-Q fluid therapy, can indicate fluid retention and possibly heart problems. If your cat feels "squishy" when you stroke him or her, this may also indicate overhydration. If your cat appears to be gaining weight rapidly or suddenly, particularly if he/she also starts coughing and/or develops a nasal discharge, starts breathing with the mouth open or has a limp, you should contact your vet as soon as possible. Further information on fluid retention and heart problems can be found on the Heart Problems page. If your cat is prone to such problems, you may wish to monitor your cat's weight with baby scales.


Weighing Scales

Tanita Digital Baby Scales 1584, which weigh in one ounce (20g) increments, are popular on Tanya's Support Group. They are available for around US$140. You might also be able to buy a set of scales secondhand from eBay or similar.


I have a Redmon baby scale which I like (it can be stored on its side when not in use, saving space), but it no longer seems to be available.


Comfort for Less sells another Redmon model for US$49.88


Amazon sells Redmon scales for US$77.95.

Salter 914


Amazon sells Salter scales for US$47.60.

Drs Foster & Smith sell Redmon scales for US$99.99.

Amazon sells the Health-o-Meter scale for US$51.97.

Digital Scales Canada sells scales in Canada starting from CAN$49.30.



Dehydration can lead to problems with constipation in CKD cats. There is a separate page about constipation here.



In many cases, diarrhoea will only last for a day. However, if it goes on any longer, or stops and then starts again, I'd recommend a trip to the vet because the cat may quickly become dehydrated (which does not only mean water loss, the cat may also be losing potassium).


Please see Waste Product Treatments for more information on how to treat diarrhoea.


Urinary Tract Issues


Blood in Urine (Haematuria)

If you can find the cause, you may be able to treat this effectively. Common causes include a urinary tract infection, bladder or kidney stones or high blood pressure.


If your vet obtains a urine sample from your cat via cystocentesis (a needle into the bladder), this may sometimes cause blood in the urine, which should resolve fairly quickly.



Proteinuria is the leaking of excessive amounts of protein into the urine. It may cause foamy urine, weight loss and swollen legs, face and abdomen. Its presence may make the CKD progress faster.


Please see the new Proteinuria page for more information.


Urinary Tract Infections and Kidney Infections (Pyelonephritis)

Please see the new Pyelonephritis and Urinary Tract Infections page for more information.



This means that the cat has limited control of where s/he urinates. This may sometimes be caused by either a urinary tract infection or occasionally by a kidney infection (pyelonephritis). A urine culture and sensitivity test should show the presence of a urinary tract infection, but will not detect kidney infections. One of our cats, Harpsie, was prone to kidney infections, partly because he had PKD (in PKD cats, the bacteria can enter the cysts in the kidneys and cause a deep-rooted infection). We always knew when Harpsie had a kidney infection because he became incontinent, but the incontinence would go away within a couple of days of starting treatment with antibiotics (although the treatment would continue for 4-6 weeks to ensure the infection was completely eradicated).


If there is no infection present, you might want to try using Vitamin B12 in the form of methylcobalamin in case that helps - some Tanya's CKD Support Group members have found it helpful.


Please also read the Inappropriate Elimination section below in case some  of it applies to your cat's situation, and for tips on dealing with the problem from a practical perspective.


While you are trying to resolve the problem, using incontinence supplies can help keep your home clean and make this stressful experience a little less stressful for you.


Incontinence Supplies


Boots the Chemist sells incontinence supplies, including protective covers for beds and chairs. You might wish to place these where your cat spends time, with a blanket on top which can be easily washed.

Pets at Home sells puppy pads - I use these ones to protect my sofas from cat vomit.


DIY stores sometimes sell plastic sheeting to protect your furnishings when decorating. It is really thin, like those bags used for fresh fruit and vegetables in supermarkets. It comes on a roll about 18ft long and 6 ft wide, and costs about £3 ($5). I used this stuff to cover the bed for Ollie, it was wide enough for my king size bed and I just cut it to the right length. It's so fine that you can't feel it on the bed, but it helps protect the bed, although urine can pool in it to a degree, plus it is so fine that it might slip off the bed, so I used mine in conjunction with a washable throw on top. I got mine from Wilkinsons.



Joybies sells piddle pants for cats in several sizes.

Pet Diapers sells pet diapers in a number of sizes.

Pet Edge sells Clean Go Pet puppy pads.

Direct Medical sells human underpads and bedpads, which usually work out cheaper, although you do have to buy a lot.

Amazon sells rubber-backed waterproof sheeting.

Amazon sells another type of waterproof sheeting.

Amazon also sells waterproof picnic blankets.

Bed Wetting Store sells a variety of products which might be helpful.


Inappropriate Elimination

This means that the cat is urinating (and sometimes defecating) in the wrong place. There can be a number of possible reasons for this, but it is definitely not done out of spite. Your cat is trying to tell you something and you need to try to work out what it is.


Sometimes this is a behavioural problem, but there may be some other reason for it in a CKD cat. Firstly and most importantly, it can be as a result of a urinary tract infection (UTI) or constipation, whereby the cat associates the litter box with the pain of the UTI or constipation, so starts urinating and/or defecating elsewhere. You should also consider the possibility of a kidney infection - our cat was prone to them and used to leak urine uncontrollably when he had one (incontinence), which could have been mistaken for inappropriate elimination. Infections and constipation can be very painful, and UTIs and kidney infections may also damage your cat's kidneys further, so if your cat urinates or defecates in the wrong place more than once, you should go to the vet as soon as possible in order to have tests done and treatment begun if necessary. 


Secondly, inappropriate elimination can be associated with the general weakness and weight loss of a CKD cat. If your litter box has a high edge, it might simply be too hard for your cat to clamber into. Try to provide a lower litter box and see if this makes a difference. 


Thirdly, the weight loss of CKD can make your cat's paw pads rather tender, which makes standing on litter uncomfortable. This can be remedied by providing softer litter, or by placing a few layers of newspaper on top of the litter which can easily be thrown away with the litter.


Fourthly, in view of their increased need to urinate, many cats simply get "caught short" and cannot make it to the litter box in time. This is easily remedied by placing several litter boxes in various locations, including on every level if your home has more than one floor, and/or by using larger litter trays.  You may also need to clean the litter boxes more often or provide more to offset the increased urination, so the cat always has a clean place in which to go.


If you have recently had new carpets laid, it is possible that the carpet actually has a urine-type aroma to the cat, which leads the cat to associate the carpets with the litter tray and urinate on them. New carpet smells like smelly urine? has more information on this intriguing possibility.


If none of these approaches helps, you need to consider the possibility of a behavioural problem not necessarily related to the CKD. As a rule of thumb, in a multi-cat household you need one litter tray per cat, plus one. Some cats prefer one litter tray to urinate in and a separate one to defecate in, and some cats like a covered litter tray, while others prefer uncovered; almost all cats prefer a tray out of the way of household traffic which offers some degree of privacy. For most cats, the bigger the litter tray, the better. Some people have had good results with a particular type of litter which is supposed to appeal to cats called Cat Attract. Try to keep the trays as clean as possible (although be careful not to clean them too much; they need to retain toileting associations for the cat), and experiment with the type of litter you use.


If your cat has been urinating in one particular spot, you need to clean it very thoroughly to remove all traces of the smell - even if you can no longer smell it, your cat, with his/her better sense of smell, probably can. Ideally you need an enzymatic cleaner which really remove the smell, though of course you must make sure you do not use a product which is harmful to cats. A product called Anti-Icky-Poo, available to purchase online in the USA here (has a link for purchasing it in the UK), or at Amazon, has an excellent reputation. After the area is completely dry, try putting a litter box in the cat's chosen spot, or if that is not possible try a food bowl (cats usually do not urinate where they eat), a pot plant or aluminium foil (cats do not like the texture).


Unfortunately, for some CKD cats, urinating and/or defecating inappropriately continues regardless of any measures you might take, and you may have to grit your teeth, minimise access to favoured zones and try to focus on the fact that this is related to the illness in some way and your cat probably can't help his or her behaviour.  We had to do this with Tanya, who seemed to get caught short, but we figured twelve years of her love more than compensated us for her behaviour. You may derive some comfort from knowing that, since CKD cats have dilute urine, most of their accidents only have a mild smell, if any. For cats who urinate on beds or sofas, try limiting their access to such areas by closing doors, or if you are reluctant to do this, cover the bed or sofa with incontinence pads or a plastic sheet (see incontinence supplies), and put a machine-washable blanket on top for the cat to lie on: this will protect the bed and so reduce your stress levels, whilst allowing the cat to lie on a comfortable but easily washed blanket. Please, do NOT rub your cat's nose in the accident, it is extremely cruel and achieves nothing, cats do not associate the punishment with their behaviour. 


Pet Place has some information about incontinence.

Hilltop Animal Hospital has excellent information from Dr Karen Overall, a well known US animal behaviourist. 

Hilltop Animal Hospital also has a series of four other articles with advice on dealing with such problems.

International Cat Care covers spraying and soiling indoors.

Common mistakes people make when trying to solve a cat's litter box problem (2012) is a blog entry by Pam Johnson-Bennett which aims to help you deal with litter box problems.



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This page last updated: 26 September 2016

Links on this page last checked: 18 April 2012






I have tried very hard to ensure that the information provided in this website is accurate, but I am NOT a vet, just an ordinary person who has lived through CKD with three cats. This website is for educational purposes only, and is not intended to be used to diagnose or treat any cat. Before trying any of the treatments described herein, you MUST consult a qualified veterinarian and obtain professional advice on the correct regimen for your cat and his or her particular requirements; and you should only use any treatments described here with the full knowledge and approval of your vet. No responsibility can be accepted.


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