News and Research

Cats: Health, Disease and Physiology: Digestive problems, kidney disease and poisoning


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Risk factors for development of chronic kidney disease in cats

Source: N.C. Finch, H.M. Syme, J Elliott
Journal of Veterinary Internal Medicine  vol 30 no2,  March-April 2016, pp 602-10 

It is worth assessing risk factors linked to cats developing chronic kidney disease (CKD), because this can help achieve an earlier diagnosis, so early treatment to prevent more damage to the kidneys. This study combined data from questionnaires and clinical evaluations on 148 cats over nine years’ old. Twenty seven cats, or 18% of the total, developed CKD. There appears to be a link between dental disease and CKD, with the risk rising with the severity of dental disease. There also appears to be a link between frequent vaccinations and cats developing CKD. Cats with a possible genetic predisposition to CKD may suffer a decline in kidney function if they have a cumulative exposure to some risk factors.  More research is needed to assess how these factors may affect cats’ kidneys.


Clinical evaluation of dietary modification for treatment of spontaneous chronic kidney disease in cats

Diet changes can help cats with chronic renal failure, or kidney disease

source: Ross SJ, Osborne CA, Kirk CA, Lowry SR, Koehler LA, Polzin DJ.
Journal of the American Veterinary Medical Association vol 229 no 6, September 15 2006
starts p949, 9 pages long

Researchers from the Department of Veterinary Clinical Sciences at University of Minnesota's College of Veterinary Medicine, have verified that altering diet in terms of protein, sodium, phosphorus, and lipids can help cats with chronic renal failure, or kidney disease (CKD). The cats on the modified diet were likely to have fewer uraemic episodes and were less likely to die of kidney disease than were cats on a normal adult maintenance diet. The study involved 45 cats with either stage 2 or stage 3 chronic kidney disease (CKD). Twenty three of the cats were fed an adult maintenance diet, and 22 were fed a special diet designed for cats with kidney problems. The cats were tested three times a month for up to two years. Cats on the special diet had significantly lower urea nitrogen concentrations, while their concentrations of blood bicarbonate were significantly higher. There were no significant differences found in the body weights of the two groups. None of the cats on the special renal diet suffered uraemic episodes, while 26% of the cats on the maintenance diet suffered uraemic crises. The cats on the special renal diet were much less likely to die from kidney-related problems, though this was not true for all causes of death.


Chronic renal failure long term management

Caring for cats with chronic renal failure

Source: Feline Advisory Bureau, Volume 39 (4) 2001
starts page 115, 2 pages long

Chronic renal failure (CRF) occurs when there is decreased blood filtration or glomerular filtration rate (GFR), which results in increased nitrogenous waste products in the blood. Treatments are aimed at maintaining the cat in stable CRF whilst preventing progression of the disease, although many treatment recommendations have been extrapolated from other species. There are many causes of CRF, including lymphoma, amyloidosis, polycystic kidney disease, glomerulonephritis and urinary tract infections. Some of these can be reversed but others are progressive. Reducing protein in the diet is useful in animals in renal failure, although there is no conclusive evidence that restricted protein diet can slow the rate of progression in early CRF. ACE inhibitors such as benazepril and enalapril reduce systemic blood pressure and studies have shown that they have a renal protective effect. Renal secondary hyperparathyroidism (RHPTH) is a complication of CRF. It is implicated in progression and uraemia, and treatment involves reducing dietary phosphate.


Constipation in the cat

Feline constipation

source: Feline Advisory Bureau Volume 39 (2) 2001, p45

Cats with constipation will have difficulty passing faeces and severe chronic constipation can lead to paralysis of the colon (megacolon). Dehydration is a common cause although other causes include obstructions due to strictures, tumours and foreign bodies. Diagnosis is based on physical examination and blood/urine tests can determine any underlying metabolic reason. X-rays may be taken to determine if a foreign body is causing an obstruction. Treatment includes giving fluids and an enema if the constipation is severe. Most cases can be managed by changing the diet to tinned rather than dry and the addition of fibre, although any underlying cause may require surgical correction.


Diarrhoea in the cat

Feline diarrhoea

source: Feline Advisory Bureau Volume 39 (2) 2001
starts page 61, 2 pages long

Diarrhoea in the cat can be due to disease, diet and infections, and the type of diarrhoea depends on which part of the intestine is involved. Diagnostic tests include blood and urine samples, faecal samples, x-rays and ultrasound, as well as biopsies. Treatment will depend on the underlying cause, but may include rehydration fluids, fasting, a bland diet and drugs to address infections or parasites. In the case of inflammatory bowel disease diet is an important part of treatment and may involve the use of novel proteins. Some cases of diarrhoea can be easily managed, but others can cause irreversible damage to the gut.


Managing the diabetic cat

Caring for diabetic cats

source: Feline Advisory Bureau Volume 39 (3) 2001
starts page 73, 4 pages long

Signs of diabetes in cats include, increased thirst, voracious appetite and weight loss, blood in urine, liver enlargement and poor coat condition, although not all signs will be present. Ketoacidosis is a complication of uncontrolled diabetes, which can result in collapse and coma. A cause of absolute insulin deficiency is the inability of the pancreas to produce insulin; a relative deficiency of insulin means that the pancreas still produces insulin, but the body cells do not respond to it properly. This may be due to obesity, the use of certain drugs such as corticosteroids or hormonal conditions. Diagnosis requires blood and urine tests and treatment involves addressing the underlying cause, dietary management, oral medication and insulin therapy. The condition may need to be stabilised and monitored within the veterinary hospital initially, and homecare requires a strict routine of insulin injections and the monitoring of glucose and ketone levels. Hypoglycaemia (low blood glucose) is a life threatening complication and requires rapid treatment in the form of food if the cat is able to eat, or the application of glucose powder/syrup to the gums if the cat is collapsed. Diabetic cats will need regular monitoring and long-term prognosis depends on the age of the cat and how easy the diabetes is to stabilise.


Feline liver disease

Liver disease in cats

source: Feline Advisory Bureau Volume 39 (3) 2001 p 89

The liver is involved in digestion, immune regulation, waste elimination, biosynthesis and energy metabolism and is particularly vulnerable to injury and disease such as cholangiohepatitis, toxoplasmosis, tumours, lipidosis, vascular disease and damage from drugs or toxins. The liver has large reserve capacity so when signs of disease become obvious, large parts of the liver are already affected. Some signs include weight loss, lack of appetite, increased drinking, vomiting and jaundice. Diagnosis is based on blood testing, x-rays and ultrasound, but a biopsy may be needed to ascertain the underlying cause. Treatment includes fluid therapy, nutritional support, antibiotics and anti-inflammatory drugs. In some cases where the disease is advanced, the liver may be severely damaged and unable to regenerate, so early diagnosis is important for treatment to be effective.


Diagnosis and management of chronic renal failure in the cat

Diagnosing and treating kidney failure in cats

source: Penney Barber
In Practice vol 25 no 6, June 2003
starts p306, 6 pages long

Kidney failure is common in cats, especially as they get older. Chronic renal failure (CRF) is three times more likely in aged cats than in aged dogs. Measurement of the cat's glomerular filtration rate is a more sensitive test for kidney dysfunction than assessing creatinine and urea plasma concentrations. A persistent low specific gravity for urine also supports a CRF diagnosis. Cats also need to be monitored after a diagnosis, and their treatment tailored according to findings.

The aim of treatment is to keep the cat's condition stable, since CRF is not seen as reversible. Cats may suffer from anorexia and dehydration, and need to be rehydrated , with electrolyte abnormalities corrected. Specific treatment may be needed for some renal diseases, such as those linked to bacterial infection of the upper urinary tract.
Commercial diets designed for cats with kidney problems can help their survival rates. These diets tend to have lower phosphorous, sodium and protein levels, and higher B vitamins, and potassium levels, as well as greater caloric density than average diets. It is easier to change a cat's diet in the early stages of the disease, since cats may lose their appetites as they become sicker, and low protein diets are less palatable for cats.

Malnutrition can cause serious problems for cats with kidney failure. Angiotensisn converting enzyme (ACE) inhibitors may help cats with CRF, but can have side effects, so the cats need to be monitored.

CRF can cause complications, such as high plasma parathyroid hormone levels, which can lead to bones being demineralised, and soft tissue calcification. This condition is tackled using phosphate restriction. Cats may also suffer from systemic hypertension, anaemia, potassium deficiencies, and infections of the urinary tract. The article examines diagnosis and treatment of CRF in cats in further detail.


Kidney disease in Persian cats

Persian cats at risk from kidney disease

source: Feline Advisory Bureau vol 38 no 1 2000
starts p29, 3 pages long

PKD affects from 35% to 40% of Persian cats, according to large-scale studies in Norway, Sweden and the US, and the UK figure could be some 25%. This disease is caused by a genetic defect, which is passed on to kittens of both sexes, and they can be affected even if just one parent has the faulty gene. Kittens inheriting the gene from both parents are not likely to survive to birth.

It is very important to assess whether cats are affected, before they breed, but the condition does not show up on tests such as palpation, and urine and blood analyses, until it is advanced. Ultrasound scanning can, however, detect the kidney cysts characteristic of PKD. There is a 98% accuracy level for ultrasound tests on cats of 10 months and older. Gene-marker tests may also become available. Affected cats go on to develop the disease, and no way has been found to prevent this, but the resulting kidney failure can then be treated by diet, though it cannot be cured. Cats can be fed low protein diets, and problems
arising from kidney failure, such as anaemia, can be treated. Prevention is important, and involves identifying affected cats. There may be a case for breeding from an affected cat, if its line is especially valuable. Some half the kittens will be affected from a mating with a cat that does not have PKD. There is concern that Persians will be affected by increased in-breeding if only PKD-negative cats are used for breeding.


Dietary news for cats

Diet for cats with kidney disease

source: Kit Sturgess
Feline Advisory Bureau vol 38, 1 p18

There is still too little knowledge about what cats with kidney problems should eat, and many recommendations come from work on species other than cats. Some changes, such as protein restrictions are needed, but the required protein level is unclear. Not all kidney diseases are the same, and cats are also genetically diverse. Cats may lack appetite when they are first ill, and low-protein diets may not appeal to them They should eat something, since this is better than their breaking down body protein. Appetite stimulators can bring benefits.

Hill's have launched a food for cats that have renal insufficiency but do not have raised urea and creatinine. The idea is that 'at risk' cases should have this diet, since it is not easy to measure renal insufficiency in cats, for practical reasons. 'At risk' cats include those that have suffered contact with renal toxins. Some breeds, such as Burmese, Siamese, and
Russian Blue are also seen as 'at risk, though it is unclear why this should be the case in Britain. Features of the new product include moderate protein restriction and slightly higher energy levels. Older cats may do better on a 'geriatric' diet that is less specific and which is geared to declining intestinal function, shown to be a characteristic of older cats.


Rational selection of gastrointestinal drugs for cats and dogs

Choosing the right drugs for cats and dogs with gastrointestinal problems

source Edward Hall
In Practice vol 24 no 5, May 2002
starts p 242, 6 pages long

An accurate diagnosis of gastrointestinal disease in cats and dogs is needed in order to choose the most appropriate drugs. Sometimes tackling the symptoms of a disease can cause more problems than it solves, by delaying treatment of the cause of the problem. Diets should be good quality and highly digestible. Antibiotics should be used only when clearly needed, due to the risks of antibiotic resistance, though risks of inducing abnormal flora through usage of antibiotics have probably been exaggerated. Antibiotics can be used where there are specific, culture-proven infections with systemic signs, in the case of haemorrhagic diahorrea, and in the case of bacterial overgrowth in the small intestine.
Other drugs used to treat gastrointestinal disease include mucosal (cyto)protectants. Sucralfate is one such drug, and, though not licensed to be used in cats and dogs, the only side effect reported is constipation. There is concern that it could interact with other drugs, such as acid blockers and tetracycline, so it is safer to time doses of the different drugs with an hour at least between them.

Acid blockers are used to help healing of gastric and oesophageal ulcers. They include antacids, H2-antagonists, and proton pump inhibitors. Antiemetics can be helpful, though they may have side-effects, such as drowsiness. Prokinetics and antidiarrhoeals are other drug types that may be indicated.

Another class of drugs used to tackle gastrointestinal problems are immunosuppressive drugs, which should be used with caution. They should only be used where a biopsy has confirmed that there is significant inflammation, and where known reasons for the inflammation have been excluded. The article examines the selection of gastrointestinal drugs in further detail.


Enteral nutrition: options and feeding protocols

Different methods of enteral feeding for cats and dogs

source: Philippa Yam and Clare Cave
In Practice vol 25 no 3, March 2003
starts p118, 9 pages long

Cats and dogs can be helped to survive ailments better if they have nutritional support. Malnutrition can affect healing by impeding tissue repair, and affecting the pet's immune system. Generally, pets that have not eaten for 48 hours, or which have eaten under half their normal intake of food for over three days can be classed as suffering from anorexia. The pet's condition and bodyweight are important. Pets that have lost over 10% in weight for reasons other than dehydration may need nutritional support.

There are a number of different ways in which food can be given, and which is the best choice depends on a number of factors, such as how long the pet is likely to need support, and whether or not the pet is in hospital. One short-term solution is to use oral/syringe feeding, which can be messy, and may not provide all the calories that the pet needs, especially in the case of large dogs. It can also lead to food aversions, and a serious possible complication is aspiration pneumonia.

Another short-term measure is feeding through a nasoesophageal tube, generally used for between three to seven days. The pet does not have to undergo a general anaesthetic to have such a tube inserted. This method is unsuitable for some pets, for example if they are unconscious, vomiting, or have respiratory problems. There is a risk that the tube could accidentally be placed in the trachea, which could be fatal, so a test for position is needed prior to each feed, for example, using sterile water. This will make the pet cough if the tube is in the wrong place. Pets should be in hospital if this method is used. The tube may also become blocked if it is not flushed after feeds. Cats, especially, may become depressed when fed by this method. Too much food at once, or chilled food, can also lead to vomiting.

Oesophaostomy tubes are used in the short and medium term. Again, they are unsuitable for some pets, for example if they are vomiting. Again, the tube can become dislodged, and this is especially true when cats are fed by this method. Tube blockage may also be a problem, but is less likely than with nasoesphageal tubes since the diameter is larger. This larger diameter also means that the pet is not restricted to a liquid diet, which is the case with nasoesophageal tubes. The insertion site needs to be kept clean to prevent infections, and should be checked every day.

Gastronomy tubes are used for the medium and long term, and are wide, so pets can be fed non-specialist diets. A general anaesthetic is needed to insert them. Pets should not be fed for 24 hours following the insertion of the tube, because of the risk of peritonitis. Pets should be checked for signs of pain, pyrexia or depression, and feeding should be halted straight away if there is any suspicion of peritonitis. The article examines enteral feeding in further detail, including how to calculate the amount of food that a pet may need.


Assisted feeding for cats

Nutritional support to help cats feed

source: Martha Cannon
Veterinary Practice Nurse vol 13 no 4, Winter 2001
starts p4, 4 pages long

Nutritional support helps cats to recover from illnesses and operations, and some cats may not survive at all without such support, which is usually easy and cheap to provide. Cats may benefit from nutritional support if they are eating less or losing weight. Cats can be tempted to eat by warming food, and they may prefer home-cooked food. They should be given just a little food, which is taken away if the cat does not want to eat, with fresh food given later. Cats should preferably have peace and quiet for their meals, with no barking dogs nearby.

Some drugs may help promote appetite, and they include diazepam injections, and cyproheptadine. Diazepam given by mouth has little or no effect on cats' appetites. Syringe feeding is another short-term option, but it can be stressful for the cat, and cats can suffer from inhalation pneumonia if they resist force feeding. Enteral nutrition involves feeding through a tube, with a liquid food appropriate for cats. This can initially lead to diarrhoea, and diluting the feed at first is a way of preventing this problem. Parenteral nutrition involves feeding through a vein, and is only used when pets cannot eat normally, since it can lead to infections, and is very expensive.

There are different types of feeding tubes using different routes. The most common are naso-oesophagal tubes, which are used for short-term feeding, and gastronomy tubes, used over the longer term. All tube feeding can have complications, such as obstructions in the tube, infections and discharges from the site where the tube enters the cat, and diarrhoea. The article discusses enteral feeding in greater detail.


Essentials of nutrition in dogs and cats with gastrointestinal disease

Dietary therapy for cats and dogs with gastrointestinal problems

source: Marge Chandler
In Practice vol 24 no 9, October 2002
starts p528, 5 pages long

Diet is important for cats and dogs with gastrointestinal problems, and sometimes dietary therapy is enough to solve the problem.

Protein deficiencies can be caused by protein not being absorbed properly, and poor quality protein fed to pets. Effects of protein deficiency include weight loss, weakness, and decreased immune function, as well as lower levels of nutrient absorption, and a higher risk of overgrowth of bacteria in the small intestine. Protein sources should be highly digestible if pets suffer from intestinal problems. The average protein digestibility for commercial pets foods is from 78% to 81%, while pets with gastric disease should have a diet with protein digestibility of 87% minimum.

Proteins account for almost all food allergens, and the common allergens vary according to which protein sources are most commonly used in a particular country. Pets with food sensitivity may have gastrointestinal problems, or skin disease, or both. The pet can be fed a protein source not previously eaten. Pets with inflammatory bowel disease may benefit from being fed one novel protein just after treatment has been started, then a
different novel protein once the intestinal inflammation has eased, since the pet may develop sensitivity to the initial protein.

White rice and cottage cheese is very digestible and unlikely to trigger allergic responses. The pet should be given twice as much rice as cottage cheese. Cats may refuse to eat cottage cheese, so boiled minced chicken could be used, so long as the cat has not previously eaten much chicken. Fish, rabbit, lamb or tofu can also be used, so long as the pet has not eaten the particular protein for at least six months. There are also special
commercial pet foods which use hydrolysed protein sources for pets with allergies. Glutamine is an amino acid that pets may need if stressed, and it seems to be more effective if fed as an intact protein, rather than hydrolysed.

Cats and dogs are less likely to be sensitive to carbohydrates, though they should be fed gluten-free, highly digestible carbohydrate sources if they suffer from small intestine and stomach problems. Gluten sensitivity has been noted in Irish setters as well as in some other dog breeds, and in cats. Affected pets may suffer from gas, diarrhoea, and overgrowth of intestinal bacteria. Boiled rice is commonly used, and barley and corn may
be tried. Tapioca and potatoes tend not to be digested as well, especially if not cooked properly. Cats with intestinal disease may have trouble digesting carbohydrates. Extruded dry food for dogs tends to be very digestible. Milk and yoghurt can trigger diarrhoea, since they contain more lactose than cottage cheese, and older dogs in particular may have trouble digesting lactose. Tapioca, bananas and raw potato contain resistant
starches that may cause problems since they are not fully digested. Elimination diets using easily digestible novel proteins and carbohydrates can be used to test for food sensitivities. The pet is started on one novel protein and one carbohydrate source, with small amounts of previously fed foods added to see if any of these trigger problems. Skin problems caused by food sensitivity tend to take longer to clear up than gastrointestinal
problems. Elimination diets should be used with care, since they are not complete, so they are unsuitable for immature pets, and should not be fed for long periods without supplements. Ingredients in commercial foods other than proteins and carbohydrates, such as preservatives, may cause problems for some cats and dogs.

Fibre may provide some benefits such as maintaining colonic motility, but is not recommended for pets with small intestine problems since it may damage small intestines that are inflamed. Diets with more fibre are also less digestible, and pancreatic enzyme activity is impaired by fibre. Fats have a high calorie content, so slow gastric emptying. Pets with gastrointestinal problems may not digest fats well, and this can cause diarrhoea. Dogs with gastrointestinal disease should have between 12% and 15% dry matter basis fat levels, while cats should have between 15% and 22%. Omega-3 fatty acids, found in fish oil and some plant oils like canola and flaxseed oil, may benefit some cats and dogs with intestinal problems. Vitamin loss may result from diarrhoea, which leads to water-soluble
vitamins being excreted at a higher rate, while pets that have problems absorbing fats may suffer from deficiencies in fat-soluble vitamins. Cats need high levels of B vitamins, so are especially at risk. Vomiting and anorexia are among signs of thiamine deficiency in cats. Supplements can be given in intravenous fluids. Vitamin E may help pets with gastrointestinal problems, given at between 10 and 100 iu/kg per day, though prothrombin activity may be impaired if doses of vitamin E are too high. Cats may also suffer from potassium deficiency.

Most pets with gastrointestinal problems should have highly digestible, frequent, small meals with novel or hydrolysed proteins, gluten free carbohydrates, moderate fat restriction, and increased levels of water-soluble vitamins. Pets with colonic disease may also benefit from fibre increases.


Advances in dietary management of obesity in dogs and cats

Different effects of diet changes in cats and dogs

source: Richard F Butterwick and Amanda J Hawthorne
Journal of Nutrition vol 128 no 12, December 1998
starts p2771S, 5 pages long

The reasons why animals are obese are not always clear, and there may be breed dispositions in dogs, but the direct cause is a higher intake of energy than is being spent. Activity levels are also important, and activity levels for dogs can vary greatly. A survey of border collies has found that most pet collies exercise for less than three hours a day. Recommendations for the calorie intake of dogs may be excessive, given the evidence of this survey on the food intake and exercise levels of collies. If these recommendations are too high, they will contribute to obesity.

Cats subjected to rapid weight loss may lose too much lean tissue. They lose weight faster if they are only allowed to eat 45% of their maintenance diet at the desired body weight, but loss of lean tissue is faster than if they are only restricted to 60% of the diet they should have at their desired weight. Dogs appear to lose less lean tissue on high fibre diets, according to one study, but not enough is known about how dogs use fibre, and how far it may contribute to energy intake. A high fibre diet does not appear to cause dogs to eat less due to feeling full. It may be better to assess whether diets for companion animals
undergoing slimming programmes are nutritionally adequate, rather than focus on fibre as a slimming aid, since evidence for high fibre diets being effective slimming aids is doubtful, and more research is needed.


Hazards at home

Poisoning risks to cats from household products

source: Alexander Campbell, from Veterinary Poisons Information Service
Feline Advisory Bureau Journal vol 38(3), July 2000 p73

Cats are at risk from household products, which can be divided into three categories: disinfectants, petroleum distillate products, and low-toxicity household products. Disinfectants can cause inflamed skin, hair loss, and severe damage to the eyes. They can be absorbed if the skin is broken. Cats may groom themselves and suffer from mouth ulcers, vomiting, diarrhoea, salivation, and appetite loss. Severe cases of poisoning can lead to respiratory problems, coughing, depression, and pyrexia. Affected cats need
prompt treatment, and should be washed, with a collar fitted so they are unable to groom themselves. Vomiting should not be encouraged, since foam can enter the lungs. Water or saline should be used to irrigate the cat's eyes, if they have been affected, and the eyes should be checked for damage to the cornea.

Petroleum distillate products include turpentine substitute. They are irritants, and can lead to depression of the central nervous system (CNS), as well as pneumonia. Cats may suffer similar symptoms to those caused by disinfectant poisoning, and in addition may suffer from tremors, tachycardia, weakness, and abdominal tenderness. Cats that inhale these
products may suffer respiratory problems, cyanosis, fever, and CNS depression. Hand degreasers or non-solvent detergents may be needed to wash the cat, which should again wear a collar. They should also be under observation at a vet's in case of serious exposure, due to respiratory risks. Cats that eat some other products, such as putty, nappy rash creams, and wax candles, may simply suffer from mild gastrointestinal problems.