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                                                                           Back to Page Index



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.

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

Amazon sells the Health-o-Meter scale for US$47.39.

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).


Slippery elm bark appears to be able to help with both diarrhoea and constipation. It soothes the lining of the gut and gives the digestive system time to heal. Psyllium may also help.


If the diarrhoea is a result of changing food too suddenly, stop feeding the new food and go back to your cat's old food until the problem is under control. Then gradually re-introduce the new food as described in Which Foods to Feed.


If your vet agrees, you can try a medication containing pectin and kaolin for a few days. However, be sure you use a formulation suitable for cats; kaopectate used to be suitable, but as the American Medical Veterinary Association explains, the formulation has changed and is no longer safe for cats. Pet Pectillin is a brand of pectin and kaolin which is safe for cats. It is available from Arcata Pet Supplies.


If the diarrhoea is caused by antibiotics, you may need to re-balance the bacteria in the gut. A small amount of natural, unflavoured yoghurt may help, but since many cats are lactose intolerant, there is a risk that this might actually make the diarrhoea worse. You may therefore find it easier to buy a commercial product instead. See the Regulation of Waste Products page for more information.


Occasionally a cat may appear to have diarrhoea, but it is in fact constipation with a small amount of liquid squeezing around the hard stool. This requires treatment for constipation.


Although loperamide (Imodium) is available without a prescription, please do not use it without your vet's knowledge and approval. According to Pet Place, it is a controversial treatment for animals, and can cause side effects in some cats, particularly those suffering from certain conditions including kidney disease. It is also hard to work out a cat-sized dose. Other treatments outlined here are much safer.


East meets west: integrative veterinary medicine (2007) Silver RJ has some suggestions for a short-term rice water-based diet suitable for a cat with diarrhoea (it is about halfway down the page). Check with your vet before using this.

Urinary Tract Issues                                                                                                                   Back to Page Index



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.


There is some evidence that ACE inhibitors, such as benazepril (Fortekor or Lotensin) or enalapril (Enacard) may help with this problem. A new treatment, an angiotensin II receptor antagonist called telmisartan (Semintra) was launched in September 2013 for the treatment of proteinuria in CKD cats in Europe. Sometimes aspirin is used, but this should only be done under veterinary supervision since aspirin can be toxic to cats.


Feeding a low protein but high quality protein food may be of some use, as may omega 3 essential fatty acid supplements. However, there is as yet no definitive evidence that these treatments are of benefit to cats with proteinuria.


Pet Place has a non-technical explanation of proteinuria (no need to register, just click on Close at the bottom of the irritating pop-up).

Assessment and management of proteinuria in dogs and cats: 2004 ACVIM Consensus Statement (Small Animal) (2005) Lees GE, Brown SA, Elliott J, Grauer GF & Vaden SL Journal of Veterinary Internal Medicine 19 pp377-385 gives suggestions for the diagnosis and treatment of proteinuria.

Protein-losing nephropathy (2005) Brunker J Compendium Sept 2005 pp686-695 has a detailed overview of proteinuria.

Proteinuria and renal disease: a round table discussion (2005) is an interesting discussion by a number of veterinary specialists about proteinuria, and CKD generally.

Cornell University College of Veterinary Medicine provides some interesting, albeit technical, information on proteinuria in cats.

The importance of proteinuria and microalbuminuria (2006) Scott SA Presentation to the World Small Animal Veterinary Association World Congress, discusses diagnostic methods for proteinuria.

The National Kidney and Urologic Diseases Information Clearing House is a human site with information about proteinuria.


Urinary Tract Infections

These are relatively common in CKD cats because their dilute urine allows bacteria to thrive. One human study, Establishment of a persistent Escherichia coli reservoir during the acute phase of a bladder infection (2001) Mulvey MA, Schilling JD & Hultgren SJ Infection and Immunity 69(7) pp 4572-9 found that in some cases the bacteria that cause urinary tract infections can burrow so deep into the bladder lining that they cannot be detected in the usual tests. In a later (2004) study reported by Science Daily, researchers found that the bacteria commonly involved in UTIs pass through four distinct developmental stages, including a dormant stage in some cases which may help explain why UTIs often recur.


Humans with cystitis are sometimes advised to take cranberries. However, cranberries are not appropriate for CKD cats (see Holistic Treatments for more information on this). The active ingredient in cranberries is D-mannose, so you could consider giving this by itself, see below.


Mar Vista Vet has an overview of UTIs in cats.



UTIs are usually treated with antibiotics. In order to be sure that the bacteria are completely eradicated and the infection completely cured, CKD cats are often given a prolonged course of antibiotics, for four weeks or longer. This is even more important for a cat with a kidney infection, where a 4-6 week course of antibiotics should be given. Urinary tract infection: how to diagnose and treat correctly (2003) is a presentation by Claudio Brovida to the World Small Animal Veterinary Association World Congress, which explains why lengthy courses of treatment are sometimes necessary.


Some vets choose to put CKD cats on a low level dose of antibiotics on an ongoing basis, or recommend pulse dosing, where the cat is given antibiotics at regular intervals for several days at a time, e.g. for the first five days of every month. If your vet wishes to do this, discuss it and decide whether you think it is a reasonable treatment for your cat: infections can be hard for the weakened immune system of a CKD cat to cope with and to recover from, so in some cases this is not an unreasonable option.


The British Medical Journal has information about a human study which showed that lactulose (which is normally used for constipation) may help prevent urinary tract infections in humans.



If your CKD cat is prone to persistent, ongoing or repeated UTIs, speak to your vet about using D-mannose, a simple sugar treatment which is supposed to be very helpful when dealing with infections where the bacteria have burrowed into the bladder wall (see above). There is more information about it on the Holistic Treatments page. If your vet recommends antibiotics, you can use D-Mannose as well, but it should not take the place of antibiotics.


Kidney Infections (Pyelonephritis)

Pyelonephritis is a bacterial infection of the kidneys. The cat may also have a lower urinary tract infection -  in some cases, untreated lower urinary tract infections rise into the kidneys - but not always. Cats with PKD are particularly prone to pyelonephritis, since the bacteria can burrow into the cysts. Our PKD cat, Harpsie, used to get regular bouts of pyelonephritis.


Please see the diagnosis section for how to test for pyelonephritis.


In order to be sure that the bacteria are completely eradicated and the infection completely cured, Urinary tract infection (UTI): how to diagnose correctly and treat (2003), a presentation by Dr C Brovida to the 28th World Congress of the World Small Animal Veterinary Association  mentions that antibiotic treatment should continue for 4-8 weeks in the case of kidney infections. The longer period is necessary because blood flow to the site of most kidney infections is poor, so it can take a while for the antibiotics to reach and kill the bacteria. You should check the urine again 7-14 days after stopping the antibiotic to make sure the infection has completely gone.


If your cat has a kidney infection, the bloodwork may improve once the infection is under control.



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: 16 September 2013

Links on this page last checked: 18 April 2012