1. Body Fluid Regulation

Increased Urination (polyuria)

The cat is an unusual animal in that it has the ability to concentrate its urine, a little like a camel; this is believed to be a legacy of its African heritage. However, in cats with CRF, this ability gradually disappears, and cats then produce a very dilute urine: the urine looks weaker in colour, has little odour, and the cat will often produce copious amounts. Some cats also lose protein in their urine (proteinuria), and foamy urine can be a sign of this. Treatment

The ins and outs of polyuria and polydipsia is an article by Dr Carl Osbourne of the College of Veterinary Medicine at the University of Minnesota.

Increased Drinking (polydipsia)

The increase in urination that occurs in CRF leads the cat to drink more and more in an attempt to remain hydrated. Some cats, like Tanya, develop new behaviours, such as drinking from showers and gutters and hanging around washbasins. Increased drinking can also be a symptom of diabetes. Treatment

Dehydration

As mentioned above, the ability to produce concentrated urine gradually deteriorates in a CRF cat as the kidneys fail. Although the cat will drink more in an attempt to compensate for the increased urination, eventually it becomes impossible to maintain a balance, and dehydration occurs.

Many people believe that dehydration means the loss of water from the body. However, it actually means the loss of both fluids and electrolytes - salts which the body needs in order to function properly.

It is not possible to diagnose clinical dehydration until the cat is already at least 5% dehydrated, so by the time you see signs, you already have a definite problem. Colorado State University gives information on the likely degree of dehydration based on physical signs (scroll down to section 7).

You should regularly check your cat's hydration levels: the most common method is to pinch the skin, usually at the scruff of the neck - the skin should fall back into place immediately. Most CRF cats experience some degree of dehydration so the skin may not fall back as quickly as in a healthy cat, but if it takes a few seconds you should look into improving your cat's hydration. Another way to check is to feel your cat's gums: they should feel slick. If they feel sticky, your cat is probably dehydrated. Sunken eyes may also indicate dehydration, as may vomiting. Cracked paw pads are also occasionally seen. Sometimes a cat with dehydration hangs his/her head over the waterbowl, though more commonly that is a sign of stomach acid. The cat may also grind his/her teeth, or lip his/her lips. Some people weigh their cats daily, finding this a good guide to their cat's degree of hydration.  

If you've ever been dehydrated, you know how awful it feels - like a bad hangover, with a dreadful headache and stomach ache. Dehydrated cats often stop eating, which then makes them even more dehydrated because they are not obtaining any fluid from their food. To make matters worse, cats who do not eat are at risk of developing a potentially life-threatening condition known as hepatic lipidosis. Therefore, it is important to detect and treat dehydration as quickly as possible. Treatment

Sneezing

This may be a sign of an upper respiratory tract infection (a cold or cat flu).

If your cat has no other signs of an upper respiratory tract infection, then the sneezing may be caused by dehydration - the nasal passages of a dehydrated cat will be drier and therefore more susceptible to irritation, such as dust.

Dental problems may sometimes cause sneezing.

Another possible cause is the long-term use of cyproheptadine, which may make the nasal tissues swell as the drug becomes less effective.

Sneezing and snorting - what should I do? (2001) is a presentation by Brendan McKiernan to the World Small Animal Veterinary Association World Congress 2001.

Constipation

In addition to concentrating urine, a cat's body also tries to conserve water by reabsorbing it from the stool through the intestinal wall. This mechanism is very efficient, and remains so even in CRF cats, and since CRF cats are largely on the edge of dehydration most of the time, the intestine will wring every drop of water out of the stool that it can, leaving it quite dry. The lack of moisture as a lubricant makes it more difficult for the cat to have bowel movements and can lead to constipation. Low potassium levels may also cause constipation, as may high calcium levels.

Symptoms of constipation include loss of appetite, pooping next to the litter tray, vomiting before, during or immediately after using the tray, dry stools or an ungainly walk. Occasionally a cat may urinate outside the litter tray when s/he is constipated - our Karma peed on the sofa so we took her to the vet for a suspected urinary tract infection, but in fact she did not have one, her problem was constipation. Once the constipation was under control, her inappropriate elimination ceased.

Sometimes a cat will appear to have diarrhoea but in fact has constipation, and the runny stool is simply what can squeeze around the solid dry stool.

Harpsie once had an episode of fast breathing and fast heart rate. He had severe constipation, and his problems resolved once he had been given an enema. If a cat is very severely constipated, toxins can back up in the cat's system causing such problems. Treatment

Meower Power has information on the different colours of cat poop.

Columbia Animal Hospital has a diagram of a cat with an impacted colon.

Urinary Tract Infections

The concentrated urine of a healthy cat has the correct levels of acidity and good bacteria, which inhibit the development of bad bacteria which multiply and cause infections. The dilute urine of a CRF cat does not offer this protection, and so urinary tract infections (UTIs) are relatively common in CRF cats: Antech Diagnostics states that up to 30% of CRF cats have them.

Urinary tract infections may manifest themselves in your cat visiting the litter tray more frequently and producing little or no urine; or there may be slight traces of blood in the urine (alternatively blood in urine is sometimes a sign of hypertension); but often there can be no obvious signs, or less obvious signs such as urinating in inappropriate places such as on rugs or beds (see below).

UTIs can be very painful so keep a close eye on your cat and seek your vet's advice if you have any doubts; it may also be worth having regular urine cultures performed. Antibiotics can usually treat UTIs effectively, though some types of antibiotic may cause inappetance and vomiting in some cats. Treatment

Reduced Urination (Oliguria) or No Urination (Anuria)

If your cat is struggling to urinate, i.e. visiting the litter tray more frequently but producing little or no urine, the most likely cause is a urinary tract infection.

Another possible cause of reduced or no urination is acute renal failure.

Certain antihistamines used as appetite stimulants such as periactin (Cyproheptadine) may cause reduced urination.

Alternatively, there is a very serious medical condition called a urinary tract blockage, which you can read about here. This is a medical emergency, but fortunately such blockages are relatively rare in CRF cats. Treatment

Incontinence

Incontinence means that your cat is unable to control when s/he urinates - s/he may urinate where s/he lies or walks, or perhaps urinate in his/her sleep. This may be caused by a urinary tract infection, or may be a symptom of uncontrolled diabetes. Occasionally, it may be your cat is simply getting "caught short", particularly if you are giving sub-cutaneous fluids, and the litter tray is a long way away. In some cases, it may indicate advanced renal damage.

Treatment

Kidney Infections (Pyelonephritis)

One of my cats gets regular kidney infections, and the main sign for him is that he becomes incontinent when the infection first appears. However, this is not inevitable with kidney infections - you may simply see more subtle signs, such as lethargy and inappetance. If you see these signs, particularly if your cat's bloodwork is worsening, ask the vet to consider that a kidney infection could be the cause.

Treatment

Inappropriate Elimination

This is a polite way of saying your cat urinates (and/or defecates) outside the litter tray. This can be a sign of a urinary tract infection or constipation, and it may also be a symptom of uncontrolled diabetes; but sometimes it is a behavioural problem. Treatment

Weight-Loss

This is a common symptom of CRF, and was the first sign with both Tanya and Thomas. Not only did they lose weight, but their spines became very bony (and their coats became dry with dandruff). This occurs because as the cat drinks and urinates more, s/he may lose protein and/or electrolytes. Weight-loss can also be associated with phosphorus imbalances or metabolic acidosis (particularly when accompanied by a bony spine), or may be a symptom of other diseases such as diabetes or hyperactive thyroid. Treatment

Swelling in the Legs (Oedema), Abdomen (Ascites) or Face

This may be a sign of proteinuria. Alternatively it may be a sign of fluid retention/build-up and/or heart problems.

Occasionally (rarely in cats), such swelling may be a sign of nephrotic syndrome. Nephrotic syndrome is not a disease in itself, but rather a collection of symptoms that may be seen as a result of glomerular disease. The primary symptoms of nephrotic syndrome include proteinuria, oedema and/or ascites, low albumin levels and high cholesterol levels. You may also see diarrhoea, reduced urine output, anaemia and occasionally saddle thrombus (a blood clot in the leg).

Treatment 

Health A to Z explains more about ascites. 

Fluid Retention/Build-Up

Sometimes a CRF cat may develop fluid retention or fluid build-up. This may be a sign of worsening kidney values  or of heart problems, or a sign of over-hydration either via IV or sub-Qs. In the worst cases, fluid may collect in the lungs (pulmonary oedema), or around the lungs (pleural effusion) or in the abdomen (ascites). 

Your cat may appear swollen in the legs, face or stomach. When Harpsie developed ascites, it felt like he had a hard little football in his stomach. However, it is normal for cats to have a soft, squishy "pouch" of fluid after sub-Qs, which may move down into the front legs; this should gradually disappear as the fluids are absorbed.

If your cat feels "squishy" when you stroke him or her, this may also indicate fluid retention caused by overhydration from excessive sub-Qs (although sometimes it merely means that air got into the line, in which case you need to work on your sub-Qs technique).

A cat with fluid retention may also show loss of appetite, because the fluid may be pressing on the stomach causing a feeling of fullness. S/he may also find it uncomfortable to lie down on his or her side. Other symptoms to watch for: if your cat appears to be gaining weight rapidly or suddenly (within the space of a few days), particularly if he/she also starts breathing from the flanks (as if pushing every breath out), coughing, purring with a rattly noise and/or develops a nasal discharge, you need to see a vet. Unfortunately, you may not always see symptoms until the problem is severe. If your cat starts breathing with the mouth open, or has a limp and the limping leg is cold to the touch, this is a medical emergency indicating heart problems and you need to get to a vet as quickly as possible. 

Do not give any sub-Q fluids if you see any of the symptoms above until you have had your cat checked by a vet. You should also never give a cat sub-Qs until the fluids from the previous session have been absorbed.

If you suspect your cat has fluid build-up, you and your vet do need to investigate this because your cat probably feels uncomfortable, and if the fluid is permitted to continue to build up, particularly in a cat with heart issues, your cat could develop congestive heart failure. However, in many cases, you may find that simply reducing the amount or frequency of sub-Qs solves the problem; so speak to your vet about this. The Intravenous Fluids and Sub-Cutaneous Fluids page has information on amount and frequency of fluids.

If your cat is prone to such problems, you may wish to monitor your cat's weight with baby scales.

Treatment 

Weight Gain

Sometimes a CRF cat will suddenly gain a lot of weight in a short period of time, a matter of days or a week. This may indicate fluid retention, and needs to be investigated urgently, particularly if accompanied by coughing, loss of appetite, breathing from the flank (as if pushing every breath out), limping, and particularly open-mouth breathing. If you see the last three symptoms, your cat's heart or lungs may be affected and you need to go to the vet immediately. Do not give any sub-Q fluids if you see these symptoms until you have had your cat checked by a vet. Treatments

Coughing

As with weight gain, coughing may be associated with fluid retention. Fluid retention may be a sign of worsening kidney values  or of heart problems, although it may alternatively be a sign of over-hydration. Fluid retention is covered in Treatments and heart problems are covered in Related Diseases.

Nasal Discharge and/or Runny Eyes

This may indicate fluid retention, particularly overhydration with Sub-Qs. See Treatments and Related Diseases. Other causes of runny eyes include an upper respiratory tract infection or dental problems.

Dull Coat/Dandruff/Spiky Fur

This reflects the general loss of condition of a CRF cat. The body is fighting a tough battle with CRF and concentrates its efforts on its more critical functions; a glossy coat is not one of them. It is also influenced by dehydration. Occasionally spiky fur may indicate a lack of essential fatty acids, or may be a symptom of hyperactive thyroid. Treatment

Feeling Hot

Sometimes cats seem to seek out cool places in which to lie, such as on tiles or in draughty places. This may be caused by hyperactive thyroid rather than the CRF, so ask your vet about getting your cat's thyroid levels checked, particularly if you are seeing other symptoms such as weight loss, howling etc.

Loss of Appetite

Loss of appetite is a very common symptom in CRF cats - because the cat feels ill, he/she feels disinterested in food. Stomach acid may also contribute to a lack of appetite. Human CRF patients have reported that their sense of smell and sometimes taste are impaired; this is thought to be caused by uraemic toxins, and probably occurs in cats too. Loss of appetite can naturally worsen weight-loss. There are several other possible causes of lack of appetite, including dehydration, high phosphorus levels, anaemia, fluid build-up, crashing, metabolic acidosis, mouth ulcers, the use of antibiotics, constipation or the use of medication for a hyperactive thyroid. 

Cats who do not eat are at risk of developing a potentially life-threatening condition known as hepatic lipidosis. Therefore, it is important to try to find the cause of the inappetance and treat it as quickly as possible. Treatment

Stomach Acid

Excess stomach acid is common in CRF cats, and in severe cases stomach ulcers may develop. Both of these are hard to detect but if your cat's stomach gurgles a lot, or if your cat has little appetite, then you should suspect that stomach acid is present, particularly in cats with creatinine levels over 265 (US:3). Sometimes the cat will appear to want to eat, but will sniff or lick the food, then walk away (this may also be a sign of mouth ulcers). Treatment 

Vomiting and Nausea

Vomiting may be seen alone or in conjunction with the other symptoms in this section. Cats who vomit a lot are more likely to become dehydrated. Vomiting is self-evident, but  it does not just include food - the classic symptom for a CRF cat is to vomit clear or white foam. Occasionally vomiting is caused by constipation, particularly if your cat vomits before, during or immediately after using the litter tray.  If you are giving your cat sub-Q fluids and s/he regularly vomits after fluids, this may because of the type of fluids used.

Sometimes there may be blood in the vomit - bright red blood is fresh blood, whilst older blood looks like ground coffee grains. This may be a sign of mouth ulcers or of gastro-intestinal bleeding, but you should contact your vet immediately if you see this symptom - our George, a non-CRF cat, vomited old blood as the first symptom of severe liver disease.

Nausea is often manifested in a lack of appetite. High phosphorus levels, dehydration or anaemia may also cause nausea. Treatment

More information about vomiting can be found at these links:

Washington State University has information on vomiting.

Coco's page has practical advice from a CRF parent.

Vet Info has information on vomiting.

Pet Place discusses the possible causes of vomiting blood.

Diagnosis and management of acute and chronic vomiting in dogs and cats (2007) is a paper by Dr TR Tams.

Newman Veterinary mentions that constipation may cause vomiting (scroll down a bit).

Hunched over Water Bowl

This can be a sign of nausea and stomach acid. Occasionally it is a sign of dehydration. Treatment

Lip Licking

This can be a sign of nausea and stomach acid. It may also be a sign of dehydration. Less commonly, it can be a sign of anaemia. Treatment

Yawning and Howling

These may sometimes be symptoms of nausea, which may be caused by stomach acid. Howling may have other causes (see howling below). Treatment

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 CRF called secondary hyperparathyroidism.

Treatment

Drooling

Drooling cats may have excess stomach acid. Dental problems  or mouth ulcers may also  cause drooling. Treatment

Bad Breath

The toxins produced by the body have an effect on the bacteria in the mouth, which can cause 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. Treatment

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.

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. Consequences of CRF has a photo of mouth ulcers in a CRF cat.  Starbrite Dental has a couple of photos of human mouth ulcers.

Treatment

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 testing. 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). Treatment

Diarrhoea

Diarrhoea is not overly common in cats as a rule, but it may sometimes be seen in CRF cats secondary to the CRF. However, there are a number of other different causes of diarrhoea, including inflammatory bowel disease (IBD), hyperthyroidism, 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, including potassium loss) and for a proper diagnosis.

Possible causes of diarrhoea in a CRF 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 CRF 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, perhaps given because of a urinary tract infection, may develop diarrhoea. The Pet Center 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, 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 mentions that potassium supplements may cause diarrhoea in humans, and presumably could have the same effect in cats.

• 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.

Diagnostic and therapeutic approach to cats with chronic diarrhoea (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.

Meower Power describes the various types of stool that may be seen when a cat has diarrheoa.

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

Newman Veterinary discusses causes of diarrheoa.

Treatments

Body Odour

Some CRF 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. Treatment 

Itching

If allergies are ruled out, this can be a uraemic itch, i.e. caused by the levels of toxins in the blood. 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 hyperactive thyroid. Treatment

Pruritus, an important symptom of internal diseases (2000) Peharda V, Gruber F, Kaštelan M, Brajac I & Čabrijan L Acta 9 (3). Scroll down to Uremic Pruritus.

Twitching

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), a hyperactive thyroid 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. Treatment

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, hyperactive thyroid, high blood pressure or occasionally just old age and possibly cognitive dysfunction (senility). 

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

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

Treatment

Hoarseness

CRF cats may occasionally become rather hoarse because of acid reflux caused by stomach acidity. In some cases, however, it may be a sign of low potassium levels. Hoarseness is also sometimes seen in cats with a hyperactive thyroid. If accompanied by coughing, consider the possibilities of fluid retention and/or heart problems.  Treatment

3. The Regulation of Electrolytes in the Body

There is a complex balance of electrolytes (salts), including potassium and sodium, in the cat's body. Electrolytes are essential to the functioning of the body at cellular level, but with increased urination, imbalances may arise in these areas, and these may have various effects as follows:

Weakness and Muscle Wasting

Weakness and muscle wasting may be commonly seen in the back legs, or your cat may have a bony spine. There are a variety of causes, including low potassium levels or high phosphorus levels leading to secondary hyperparathyroidism. Muscle wasting may also be caused by metabolic acidosis, while weakness in the back legs is occasionally caused by low magnesium or low calcium levels.

General weakness may be caused by anaemia, or because the cat is simply not eating enough. It is essential that cats eat, because if they do not eat, they are at risk of developing a potentially life-threatening condition called hepatic lipidosis. The Persuading Your Cat to Eat page has tips on persuading your cat to eat.

If your cat is diabetic, the weakness may be caused by diabetic neuropathy. The Mayo Clinic has information about peripheral neuropathy, including that caused by diabetes. You may also see a plantigrade posture, where the cat walks on his/her hocks instead of his/her feet: this is most common in diabetic cats, but may sometimes be seen in cats with neurological problems from other causes. Long Beach Animal Hospital has a photograph of a cat with diabetic neuropathy doing this (click on Symptoms). Newman Veterinary has a good before and after photo of a diabetic cat with this problem, scroll down a little to Other Common Consequences, then click on Plantigrade Stance (in red font).

If your cat no longer jumps, this may be thought to be weakness when in fact it is an unwillingness to jump because of blindness caused by hypertension. An inability to jump or climb may also be caused by arthritis. Treatment 

Stilted Gait in the Front Legs

This is usually a sign of low potassium levels. Treatment

Stiff Neck or Inability to Hold Up Head (Ventroflexion)

The cat may be unable to raise his or her head properly - in most CRF cats, this is a symptom of potassium deficiency. Very occasionally, this may be a sign of thiamine (Vitamin B1) deficiency, which is sometimes seen in cats fed too much fish. Treatment

Diagnosis and management of chronic renal failure in cats (2000) Sparkes A, has a photo on page 4 of a cat with this condition.

Long Beach Animal Hospital has a photograph of a cat with this problem - scroll down to find the photograph.

Consequences of CRF has a photo of a cat with this condition at the end of the page.

The feline patient: cervical ventroflexion (2007) Mitchell A Crystal discusses this problem and also has a photograph. If necessary, search for "ventroflexion cat" to find the relevant book and page - it should be the first one in the list.

Hoarseness

A hoarse cat may have low potassium levels, which are adversely affecting the cat's vocal chords. Alternatively, this is sometimes a sign of stomach acid. If accompanied by coughing, consider the possibilities of fluid retention and/or heart problems. Treatment

Increased Night-time Urination

One peculiarity which you may see is nocturia, or excessive urination during the night, which may be caused by low potassium levels. If you only give your cat sub-Qs late at night, this might also be the cause. Treatment

Constipation

This may be a sign of low potassium levels. It may also be caused by dehydration or high calcium levels.

Seizures

Potassium levels in CRF cats are often too low, but if they become elevated, which may happen as the CRF progresses, heart problems can arise, and short seizures may also occur, especially in end stage renal failure. 

Seizures can also be a sign of high blood pressure, high levels of toxins, metabolic acidosis or of calcium imbalances. The use of Reglan (metoclopramide) 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 CRF cat and should therefore be considered first. Treatment

Twitching

Twitching may be related to potassium levels in the body. In early CRF, it is likely to be due to potassium levels being too low, which can be treated with potassium supplements. However, in end stage CRF, potassium levels may rise and cause twitching as happened to Thomas on his last day.

Other causes of twitching include high phosphorus levels, a hyperactive thyroid, high blood pressure, calcium imbalances (especially head twitching) or Vitamin B deficiencies. Twitching may also be caused by toxin levels in the blood. 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. Treatment

Metabolic Acidosis

Bicarbonate ions (which are alkaline) in the kidneys help protect against acid build-up in the body until the kidneys can get rid of it; but the excessive urine flow of CRF washes the usual bicarbonate ions out of the kidneys. Acid levels then rise in the blood, which promotes muscle breakdown, and weight loss - particularly lean muscle loss - results.

Acidosis occurs in 65-75% of cats with kidney failure, so it is important to check for this and treat it if necessary. Symptoms include weight loss, lean muscle loss, a bony spine, weakness, vomiting, twitching, and sometimes mouth ulcers or breathlessness. Breathlessness caused by metabolic acidosis is known as Kussmaul breathing.

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

Other causes of seizures in CRF cats include high potassium levels, high blood pressure, high levels of toxins, or calcium imbalances. The use of Reglan (metoclopramide) 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 CRF cat and should therefore be considered first. Treatment

4.  Regulation of Minerals in the Body