Topic of the Month
Every month we discuss a topical issue - this month Feline Idiopathic Cystitis:
Feline Idiopathic Cystitis
(including information taken from an article by Anne Seawright BVScMRCVS)
Feline Idiopathic Cystitis or FIC describes cat cystitis, or inappropriate urination where there appears to be no physical cause or medical problem. These are cases where the typical urinalysis, internal imaging and blood screens show no illness or abnormality.
On further investigations, cats with FIC are seen to have relatively normal epithelium and muscularis layers on hystopathology, but may show submucosal oedema and an increase in bladder wall and vascular permeability. There tends to be minimal inflammatory infiltrate although mast cells are often present. Biopsies often show an increase in the number of pain fibres (C-fibres) and pain receptors. The C-fibres can be stimulated through either stress or low urine PH resulting in the hystopathological changes seen.
This inflammation may result in significant urethral spasm, which will contribute to the clinical signs and may be severe enough to cause urethral blockage or scarring. The spasm may be exacerbated by use of an indwelling catheter and may be a cause of dysuria after an obstruction has been relieved. Some cats with FIC have been shown to have a decrease in excretion of urinary glycosaminoglycans (GAG's). It is thought that the decrease in the normal GAG layer that lines the urothelium helping to protect the bladder wall from the noxious components of urine may predispose to urothelial damage and inflammation.
These findings have shown a number of similarities between FIC and interstitial cystitis in humans.
FIC reveals abnormalities in the normal stress response systems, with stress exacerbating the symptoms.
Cats with FIC have significant increases in plasma noradrenalin and dihydroxyphenylacetic acid as well as a trend towards increased adrenaline levels, suggesting an increase in sympathetic activity. ACTH stim. tests revealed a blunting of the adrenal cortex response and cases studies have revealed cats with FIC have small adrenal gland size. These results suggest a dissociation of the body's two major stress response systems, typical in animals suffering from chronic stress.
Several studies show that environmental factors that cause stress to cats are important "flare factors" in cases of FIC. Cats living in conflict with other cats within the same household was the most influential. Conflict with another cat was a factor in 72% of cases in a recent study at Bristol University. Other flare factors were moving house in the previous 3 months, changes in owner routine, changes in interaction with the cat, and increase in days of rainfall. The environmental factors will differ with the specific learning experiences of each individual cat. For example, a busy household at Christmas may precipitate a bout of FIC disease in a cat that is poorly socialised.
FIC is complex and likely to have genetic predisposing factors. However this predisposition is compounded by exposure to prolonged, inescapable or unpredictable stressful events to precipitate the disease.
Treatment
Urinary modification by altering the PH and mineral level of the urine through diet. The most important factor is urinary concentration. Water turnover should be increased to dilute the urine as much as possible. This can be done by leaving dripping taps, making fresh clean drinking water available through several locations within the house,using a water drinking fountain, flavouring the water and diluting food with water. Cats should be removed from a dry food diet that does not have an S/O factor. Cats should also have access to a clean litter tray in a safe secluded area, away from their food source. Additional litter trays help provide the cat with constantly available clean litter. In multi-cat households it is advisable to offer access to a litter tray for sole use.
Replacing glycosinoglycans can be beneficial however there appears to be a variable clinical response.Clinical trials have shown no overall significant improvement in recurrence rates of FIC. Despite this some individuals do respond well with glycosaminoglycan replacements, with signs of FIC recurring when replacement therapy is stopped.
Behavioural therapy to identify the "flare factors" involved and then utilising the cats perception of stressors through desensitisation and counter-conditioning is useful. Client compliance with behavioural advice changes, removing "flare factors" where possible and understanding of the cat's condition is essential for any useful outcome in behavioural therapy. In some cases drug therapy is indicated in addition to behaviour therapy. The tricyclic antidepressant, amitriptyline has been found to be beneficial. It has anxiolytic effects and direct anti-inflammatory and analgesic action in the bladder. Clinical trials have shown variable results suggesting that short-term use is not efficacious in reducing clinical signs. A study in long-term used showed a benefit in some individual cats. Potential side effects include somnolence, urinary retention and an increase in liver enzymes. It is suggested that drug anxiolytic therapy should be reserved for cats where their threshold to stress response is low and it is particularly difficult to remove or reduce the environmental stressors.
Feliway diffusers can be used as de-stressing agents within the house. This synthetic analogue of the F3 fraction of faecal pheromone can aid the behavioural therapy by making the cat feel less stressed.
FIC is painful and distressing to the cat. It can lead to excessive grooming and even self trauma. Analgesia (e.g. NSAIDS) can reduce the clinical signs in some cases.
Where urethral spasm is suspected both smooth and striated muscle relaxants should be used to act on both the internal and external sphincter muscles.
They are commonly used at the time of presentation and for 5-7 days after.
Corticosteroids have shown to have no effect on the resolution of clinical signs. Cats with Lower urinary tract signs may be given antibiotics but bacterial involvement is only seen in a minority of cases. Bacterial culture and sensitivity should be performed to identify and appropriate antibiotic where bacterial involvement is suspected.
The conclusion is that there are still more scientific studies to perform to understand the full nature of FIC. Removing stress "flare factors"/behavioural therapy/drug therapy/changing the diet is the current treatment option.