Urinary tract diseases in cats
Urinary problems are a very common cause of veterinary visits for cats. As desert animals, cats drink very little, because in the wild they get the fluid they need from their prey, and feline water metabolism is adapted to produce very concentrated urine. Cats that eat only dry food are especially susceptible to dehydration. Insufficient intake of fluids exposes the cat to urinary saturation and various urinary problems, which affect both males and females. The most common urinary problem in cats is stress-related inflammation of the lower urinary tract. Feline Lower Urinary Tract Disease (FeLUTD) and Feline Idiopathic Cystitis (FIC) commonly occur in neutered and overweight cats. Urinary tract infections in cats are not very common compared with dogs.
The owner often notices that urinary problems are changing the cat’s urination behaviour. The cat may urinate with traces of blood and urinate elsewhere than in its own litter box. Urinating may also be painful. The cat normally urinates with its back straight and its hind legs close to the ground. In urinary problems, the position of urination often changes so that the cat curls its back and raises its rear end higher. Crying when trying to urinate is a clear signal of pain. Pain signals can also be unclear, such as aggression, withdrawal, and hiding. Sometimes a urinary tract infection and pain become evident when the cat licks its stomach or urethra constantly. In some cases, the only sign is abdominal alopecia. Haematuria indicates inflammation of the urinary bladder. If the cat is unable to urinate at all, it should be taken to see the vet immediately to rule out a blockage in the urinary tract, which can be fatal.
You can try to prevent urinary tract problems by providing your cat with high-quality meaty food, making sure it has plenty of drinking water, and avoiding stressful situations. The water should be clean and fresh, served in a clean bowl, and changed regularly. A cat should have several litter boxes, with litter chosen according to the cat’s preferences. Litter boxes need to be cleaned often, because cats are tidy animals and do not want to visit a stinky toilet. It is good to observe the weight of the cat, and it is also advisable to play with the cat so that it can act out its natural predatory behaviour.
FLUTD is a generic term for feline lower urinary tract diseases. The lower urinary tract includes the urethra and bladder. FLUTDs include feline idiopathic cystitis FIC, bacterial infection (rare), cancer cells or tumours in the urinary tract (neoplasia), anatomical abnormalities, blockages, and uroliths (urinary crystals or urinary stones). FLUTD symptoms are the most common cause of feline veterinary visits (1), of which 60% are caused by FIC, 20% by uroliths, 15% by blockages, and the rest by other causes. The different symptoms of FLUTD are:
- Dysuria: urination causes pain
- Pollakiuria: the cat urinates frequently in small volumes
- Haematuria: traces of blood in the urine
- Periuria: the cat urinates elsewhere than in its own litter box
- Stanguria: the cat cannot urinate properly, there may be a blockage in the urethra
- Anuria: the cat does not urinate at all
FLUTD symptoms are common in cats. Certain factors increase the risk of lower urinary tract diseases:
- Sterilization or castration
- Overweight and obesity
- Limited exercise and limited opportunities to play or ‘prey’
- Lack of outdoor opportunities
- Stress in the cat’s environment
- Restrictions in territory
- Eating only dry food and insufficient fluid intake
Idiopathic cystitis, FIC
Feline idiopathic cystitis is an infection of the bladder for which there is no clear external cause. It is a so-called sterile infection, meaning it is not caused by a bacterium or virus. The cause of feline idiopathic cystitis may be unclear, but in most cases stress is the most important factor. The urinary bladder in cats is referred to as ‘stress target organ’, because the cat’s brain has a direct connection to it through the nervous system. Stress accelerates the functioning of the sympathetic nervous system (SNS), which is responsible for activating the so-called ‘fight or flight’ response. This, in turn, causes an increase in the quantity of certain hormones in the cat’s body, resulting in stimulation of peripheral nerves through the central nervous system (2). Nervous system stimulation and abnormal levels of adrenaline and noradrenaline in the body can cause changes in bladder epithelial permeability, the secretion of inflammatory mediators into the bladder epithelium, and pain in the bladder. The pain continues to cause additional stress, with idiopathic cystitis forming a self-feeding spiral.
When FIC is suspected, the cat is usually examined for a bacterial or precipitated urine sample, and the urinary tract is examined by either X-ray or ultrasound. This can rule out tumours, urinary crystals, or stones and other causes of urinary problems. A urine sample from a cat with FIC may contain blood or inflammatory cells, but not, for example, bacteria that would explain the infection. A cat’s urine sample may contain precipitate or crystals (so-called crystalluria); however, this is not the cause of FIC but rather a result of over-saturated urine. Because FIC is not caused by bacteria, antibiotics are not a useful treatment. A cat with idiopathic cystitis may be aggressive or withdrawn and have frequent and painful urination. The cat may also lick its stomach or urethra.
Overweight and sterilization/castration increase the risk of FIC. These factors reduce the cat’s desire to play and move. Adipose tissue produces inflammatory factors throughout the body, including the bladder, which is why efforts should be made to help an overweight cat achieve and maintain its ideal weight. An analgesic is usually effective in relieving FIC symptoms. A special diet designed for urinary tract wellbeing should also be started. Added to food, the amino acid tryptophan can help reduce stress levels. Dietary omega-3 fatty acids can also help reduce bladder inflammation. In stress-derived FIC, the cause of stress should be identified and minimized, and the cat should regularly be given the opportunity for controlled outdoor activities in order to act out its instinctive predatory habits through play. Adequate hydration must be maintained to keep the urine dilute and encourage the cat to urinate frequently and flush the bladder. The litter boxes used by the cat should also be kept clean, and there should be enough of them to comfortably accommodate all the cats in the household.
Bacterial urinary tract and bladder infections are most common in older cats, but unlike dogs, bacterial inflammation is generally quite rare in cats. If a cat has developed FLUTD at a young age, there is an increased susceptibility to bacterial infections in the cat over 10 years of age. Idiopathic cystitis is most common in young cats and very rare in older cats.
Uroliths – urinary crystals and urinary stones
Urine crystals and urinary stones are the second most common cause of FLUTD symptoms in cats. The most common urinary formations in cats are either struvite stones or calcium oxalate stones, but mixed types are also found. Urine pH influences what type of stone forms in the urinary tract. Struvite crystals begin to form when the urine pH is above 7, and calcium oxalate stones occur when pH falls below 6. The ideal urine pH is 6.2 to 6.4, because at this pH, neither type of stone can form. Crystalluria refers to small crystals in the urine that can lead to the formation of urinary stones.
Several factors contribute to the occurrence of urinary stones. There must be material in the urine around which the stones can begin to crystallize. The material may be, for example, epithelial cells in the urine. When urine is rich in precipitating material, it is referred to as supersaturated urine. Bladder stones are also associated with inflammation of the bladder.
The risk of urinary stones is increased by the cat’s age, sex, diet, genetic susceptibility, urine composition, and other health factors. Incomplete bladder emptying increases the risk of stones, as does insufficient or infrequent urination, which prevents small crystals from being flushed out of the bladder. Drinking too little water also concentrates the urine.
Struvite stones are the most common type of urinary stone observed in cats. They consist of phosphate, ammonium, and magnesium. They are smooth stones that may dissolve with the correct diet. Struvite stones begin to dissolve as the pH of the urine drops to between 6.2 and 6.4. However, dissolution is not always effective, and surgical treatment may be necessary. A special diet from a veterinarian is used to dissolve the stones. If a cat is prone to struvite stones, a special diet can also be used prophylactically to maintain optimal urine pH and urinary tract wellbeing.
Calcium oxalate stones are prickly and sharp-edged and cannot be dissolved through diet. It may be possible to flush calcium oxalate stones from the bladder, but they may need to be removed surgically. Surgery can increase the risk of new stones forming, as the scar area provides crystallization substrates for new stones. Some Oriental cat breeds are more susceptible to calcium oxalate stones. Certain diseases, such as hyperthyroidism, can alter a cat’s metabolism so that oxalate stones begin to form more sensitively. However, this is a secondary symptom of another disease.
Diet is essential especially for struvite crystals. The predisposing factor for the formation of struvite stones is, for example, the wrong kind of nutrition. High levels of phosphorus and magnesium in food increase the risk of struvite crystals. Grains are especially rich in magnesium. Urinary stones are more common in males, because the male cat’s urethra is longer than the female’s and tapers towards the end. For this reason, urethral obstructions are more common in male cats. Blockages are almost always caused by struvite stones, and very rarely by calcium oxalate stones.
Brit VD Struvite
Brit VD Struvite is a supportive diet for feline idiopathic cystitis formulated to prevent crystalluria and prevent and dissolve struvite crystals and struvite stones in the urinary tract. In order to prevent urinary mineral over-saturation, Brit VD Struvite is low in magnesium, calcium, and phosphorus. Methionine, a urine acidifier, and buffers are added to Brit VD Struvite to help maintain a balanced urine pH of 6.2 to 6.4. This promotes the dissolution of struvite crystals and prevents the formation of oxalate crystals.
Brit VD Struvite is rich in the amino acid L-tryptophan, the precursor to the hormones serotonin and melatonin. Tryptophan may help relieve stress reactions in cats, which are considered to be the major cause of idiopathic cystitis.
Added sodium improves fluid intake and promotes urinary excretion. Brit VD Struvite has also been enriched with cranberries, which not only acidify urine but also prevent E. coli from attaching to the urinary tract epithelium, thus helping to reduce the risk of bacterial urinary tract infections. Omega-3 DHA and EPA help prevent inflammation in the bladder.
Brit VD Struvite is grain free and gluten free and contains the live probiotic E. faecium to stimulate the immune system. The added amino acid L-carnitine plays an important role in fat metabolism and helps maintain muscle condition. Brit VD Struvite should not be used with other urinary acidifying agents and is not suitable for cats with chronic kidney or heart disease.
Once the veterinarian has diagnosed struvite stones or crystals, the food should be fed to the cat for 5 to 12 weeks to dissolve the stones. The cat’s urine should be analysed, and the urine pH checked regularly. The food should not be changed without a veterinarian’s assessment.
1) Veterinary pet insurance data, US, 2005
2) Buffington CAT, Chew DJ, Woodworth BE. Feline Interstitial Cystitis. JAVMA 1999; 215 (5)9