FELINE lower urinary tract disease (FLUTD) is the term used to describe conditions that affect the bladder and/or urethra of cats. The feline lower urinary tract can only respond to insults in a limited number of ways so differentiating between different causes of FLUTD can be challenging. Typical clinical signs encountered in FLUTD include:
- dysuria – difficulty urinating;
- pollakiuria – increased frequency of urination;
- stranguria – pain on urination;
- haematuria – blood in the urine;
- periuria – inappropriate urination;
- behavioural changes – increased aggression, becoming withdrawn, etc.;
- overgrooming of perineum, ventrum or medial thighs.
The most common cause of FLUTD in cats under 10 years of age with non-obstructive disease is feline idiopathic cystitis (FIC) which accounts for nearly twothirds of cases (Figure 1). Less commonly, clinical signs may be due to urolithiasis (15%), anatomical abnormalities (10%), behavioural disorders (7%), bacterial infection (2%) and neoplasia (1%).1 Feline idiopathic cystitis
Feline idiopathic cystitis
(FIC) is seen most commonly in young to middleaged cats with males and females being equally at risk. Several risk factors have been identified for cats to develop FIC: being overweight or neutered, leading a sedentary lifestyle, eating a dry diet, living in a multi-cat household, using an indoor litter tray and having restricted access to outdoors have all been shown to predispose a cat to developing FIC.2 The underlying aetiology in FIC remains unknown but many hypotheses have been put forward. The most widely accepted of these is that FIC is the result of complex interactions between several body systems including the neuronal supply to and from the bladder, the protective glycosaminoglycan (GAG) layer and compounds within the urine (Figure 2). Biopsies taken from affected cats have shown increased numbers of pain fibres (C-fibres) and pain receptors (substance P receptors). The C-fibres can be stimulated, either by the brain (in response to stress) or by local triggers within the bladder (e.g. protons, potassium ions or concentrated urine). This stimulation of C-fibres results in release of neuropeptides, such as substance P, which in turn results in pain, vasodilation, oedema, smooth muscle contraction and increased permeability of the bladder wall.3 The GAG layer provides a protective barrier for the sensitive bladder urothelium which acts to prevent the adherence of bacteria and crystals. Damage to the urothelium and the overlying GAG layer can allow the contents of the urine to activate the C-fibres, which may be perceived as painful by the rain. Compared to normal cats, some cats with FIC have decreased urine concentrations of GAG, decreased surface GAG expression and increased bladder wall permeability.4 The response to stress in cats with FIC is different to normal cats: affected cats have abnormalities in the hypothalamic-pituitary-adrenal axis (HPAA) with significantly decreased plasma cortisol responses to exogenous ACTH and reduction in the size of the adrenal glands when compared to normal cats.5 In addition to this, cats with FIC have increased activity of the enzyme, Tyrosine hydroxylase, in the pontine locus coeruleus.6 This enzyme catalyses the synthesis of noradrenaline, with resultant increases in plasma noradrenaline concentrations and therefore increased sympathetic drive in affected cats.
Stress
Stress is an important trigger or exacerbation factor for FIC. Stress can be defined as “any physical, chemical, or emotional force that disturbs or threatens homeostasis, and the accompanying adaptive responses that attempt to restore homeostasis”.7 This stress can be environmental, physiological, psychological or due to co-morbid/concurrent disease. Stressful events such as earthquakes, seasonal weather changes, moves to a new home, major holidays and diet changes have all been associated with lower urinary tract signs in cats.8,9,10 Potentially, stressors will vary from cat to cat and be dependent on many factors, such as: individual responses to stress, experiences during the socialisation period, specific learning of the cat during its life and the severity and chronicity of the stressor.11 The most significant trigger of stressful episodes seems to be inter-cat conflict, either between cats within the same household or between cats in different households.
Management options
The approach to managing cats with FIC is a multi-modal approach. This can include:
- Analgesia and anti-inflammatory drugs – FIC is a very painful condition and cats should be made as comfortable as possible, which in turn will reduce stress levels.
- Manage stress – ideally the stressor should be identified and addressed where possible.
In the case of multi-cat households it is important to appreciate the social groups and the provision of adequate resources for these groups. Each social group needs access to sufficient litter trays, food, water and resting places. While addressing the environment is vital, some cases may require additional therapies to control stress levels. This can include the use of prescriptiononly medications, such as tricyclic antidepressants (TCAs) and selective serotonin reuptake inhibitors (SSRIs), or nutraceutical options. Products that have shown to be useful at reducing stress-related behaviour in cats include L-tryptophan, alpha-casozepine and synthetic F3 facial pheromones.
- Create dilute urine – the aim is to produce urine with a specific gravity around 1.035. This will encourage frequent urination and dilutes any noxious compounds within the urine.
- GAG supplements – examples include N-acetyl D-glucosamine and hyaluronic acid. The aim is for these exogenous GAGs to attach to the defective urothelium and decrease bladder wall permeability. They may also have analgesic and antiinflammatory effects.
Summary
Stress provides an important flarefactor in the pathogenesis of FIC. Clinicians should address possible stressors as part of a multimodal approach to the management of this debilitating disease.
- Buffington, C. A. and Chew, D. J. (2001) Management of non-obstructive idiopathic/interstitial cystitis in cats. In: BSAVA Manual of Canine and Feline Nephrology and Urology. Eds: Elliot, J. and Grauer, G. F. BSAVA, Gloucester.
- Willeberg, P. (1984) Epidemiology of naturally-occurring feline urologic syndrome. Veterinary Clinics of North America Small Animal Practice 14: 455-469.
- Gunn-Moore, D. A. (2001) Pathophysiology of Feline Lower Urinary Tract Disease. UK Vet 6 (5): 20-32.
- Buffington, C. A. et al. (1996) Decreased
