Inflammation of the bladder (cystitis) is a relatively common problem in the cat. The symptoms include frequent urination, or repeated attempts at urination with passage of only small amounts, plus difficulty and pain on urination, and blood in the urine. Other signs include urination in places other than the litter box (often the bath or shower), or behavioural changes such as depression, aggression or urine spraying.

Cystitis can sometimes result in a blockage of the urethra (the tube connecting the bladder to the outside), particularly in male cats. The bladder then fills, becoming painful, and potentially producing damage to the kidneys. This can be rapidly fatal, within 24 hours. It is vital that any cat that appears unable to urinate is seen urgently by a vet.

What causes it?
The precise cause is unclear, but factors that contribute include stress, a low water intake and the production of urine containing mineral crystals. Unlike in people, cystitis is not usually just an infection, although this occasionally occurs in older cats, especially those with kidney problems. Overweight cats and indoor cats appear to be more prone, possibly because they are less active

My cat stressed?
Cats today live very differently from their natural ancestors. Although wild and feral cats do sometimes meet and have cat friends, they are solitary hunters who prefer (unlike people and dogs) to eat alone. Indeed they enjoy their own company and wild cats will often hide away and conceal themselves from human (and other) eyes, often making them difficult to find.

Urine and faeces may be used for territory marking and when this happens are left clearly visible. Usually when cats are going to the toilet they choose to relieve themselves in private and will bury the evidence in order to reduce the risk of infection and decrease the chances of being located by potential predators or adversaries.

Cats are adaptable but in many domestic situations they find the pressure of living with people and other cats quite stressful. This is especially true if there is more than one cat in the household and if these cats are not related to one another in any way. The problem is exacerbated if the cats are forced to share important resources such as food and litter trays. The pressure of coming together into one room in order to have set meals provided for them can be particularly stressful. It's a bit like having to sit down daily to a family dinner whilst you have a particularly annoying relative staying. You don't like them any more as a result.

How does all this affect the bladder?
The exact effect of stress on the bladder is not fully understood, but changes seem to occur in the nerve supply to the bladder wall, which sensitise it to pain and inflammation. There are also alterations in the bladder's protective lining so it loses its waterproofing which means that urine, which is irritant, penetrates the wall, worsening the inflammation.

Drs I de Best, MRCV