23 Sept 2013
STEPHANIE JAYSON, MAYANK SETH explain the process of diagnosing this common cat ailment, before then identifying the various methods of short and long-term treatment
Feline idiopathic cystitis (FIC) is a common condition that is diagnosed by exclusion of other known causes of FLUTD. Urinalysis and abdominal radiographs are recommended at least once for all cases. The pathogenesis of FIC is incompletely understood and an improved understanding could help guide future therapy. The goals of management are to control acute episodes and reduce the severity and frequency of clinical signs in the long term. Acute obstructive episodes present as a medical emergency, requiring intensive stabilisation prior to relief of obstruction by catheterisation. Long-term management is based on environmental modification and conversion to a wet diet. Feline facial pheromones and glycosaminoglycans may be used as adjunctive therapy, but there is insufficient evidence to support their use as sole therapeutic agents. There is some evidence to suggest amitriptyline may be useful for long-term management; however, its use as a short treatment course is not recommended.
FELINE lower urinary tract disease (FLUTD) or feline urological syndrome (FUS) is considered to be one of the most common diagnoses in feline patients, affecting one per cent of cats annually in the UK1.
The term FLUTD is used to describe a combination of clinical signs associated with irritation to the feline bladder and/or urethra, including:
• dysuria (difficult urination);
• haematuria (presence of red blood cells in urine);
• periuria (urination in inappropriate places);
• pollakiuria (increased frequency of urination); and
• stranguria (straining during urination)2.
These signs are non-specific and may result from a variety of disorders affecting the lower urinary tract.
Despite its common occurrence, the aetiology of FLUTD is poorly understood. Causes include urinary tract infections (UTIs), uroliths, urethral plugs, neoplasia, congenital and acquired anatomical abnormalities, neurogenic disorders and traumatic and iatrogenic damage3.
However, in most cases no cause is identified and these cats are classified as having feline idiopathic or interstitial cystitis (FIC)4,5,6. FIC is more common in cats aged between one to 10 years (55 per cent to 64 per cent of cases) than cats more than 10 years old (less than five per cent of cases) and typically resolves within five to seven days, with or without treatment4,5,6,7.
As clinical signs of FLUTD are non-specific, diagnosis of the underlying cause requires evaluation of signalment, history, physical examination, urinalysis with sediment examination, urine culture and sensitivity testing and imaging of the urinary tract2.
FIC is a diagnosis of exclusion, therefore, a complete diagnostic work-up is required. However, if there is a high index of suspicion of FIC – for example, a young cat presenting with FLUTD that resolves within five to seven days – the clinician may choose not to pursue costly diagnostic tests, unless there is an increase in frequency or severity of clinical signs.
Urinalysis with sediment examination is recommended at least once, for all cats with FLUTD, however, findings are non-specific2. Typical findings in FIC cases are absence of white blood cells and variable haematuria, proteinuria and crystalluria7. Urine culture and sensitivity testing may not be necessary in cats less than 10 years old presenting for the first time with FLUTD, as UTIs are rare in this age group (one to eight per cent of cases)4,5,6.
UTIs are much more likely in cats that are more than 10 years old (approximately 50 per cent of cases), have undergone urinary tract procedures – for example, repeated catheterisations or perineal urethrostomy – or have concurrent chronic renal disease, diabetes mellitus or hyperthyroidism2,8. Culture and sensitivity testing is therefore recommended in these cases and in all recurrent (two or more two episodes) FLUTD cases2.
Plain abdominal radiographs are useful to detect radiodense uroliths – for example, magnesium ammonium phosphate (struvite) or calcium oxalate – greater than 3mm in diameter (Figure 1a)7. The entire urinary tract should be included, to allow for assessment of concurrent upper urinary tract disease, as distal ureteral obstruction can cause FLUTD signs in the absence of bladder or urethral involvement (Figure 1b).
Contrast radiography and abdominal ultrasound may be indicated if clinical signs are recurrent or persistent. These imaging modalities permit detection of some of the less common causes of FLUTD, including small or radiolucent calculi – for example, urates or cystine – neoplasia, urachal diverticula and polyps7.
Uroendoscopy allows visualisation and biopsy sampling of the bladder and urethra; however, it is rarely used in practice, due to its limited availability.
Although an initial acute episode of FIC lasts only five to seven days – with or without treatment in 92 per cent of cases – recurrence of clinical signs occurs in 39 to 65 per cent of acute FIC cases within the first year of the initial episode3.
Recurrence may represent a true recurrence of the initial disease; however, clinical signs could also be due to a delayed effect of the original disease or another cause of FLUTD – for example, urolithiasis. Rarely, FIC cases are classified as chronic, in which FLUTD persists for weeks to months or is frequently recurrent3.
The pathogenesis of FIC is poorly understood and the reason why it recurs is unknown. Hypothesised aetiologies include bacterial or viral pathogens, defective urothelial proliferation, dysfunction of the urothelial barrier, mast cell secretion, neurogenic inflammation, psychoneuroendocrine disease, struvite crystalluria and vesicourachal diverticula3
Without a robust understanding of its aetiology, there is considerable debate about treatment of FIC. It is important to inform owners that with no known cure, the goals of therapy are to achieve clinical recovery in the short term and increase the interval between episodes and reduce the severity of clinical signs in the long term.
• Non-obstructive FIC
FIC may be obstructive or nonobstructive, depending on the patency of the urethra. An initial episode of non-obstructive FIC may be managed with analgesic therapy for three to five days, with the aim to break the paininflammation cycle2. If there is no clinical improvement after this time, further diagnostic tests are warranted to rule out other causes of FLUTD.
• Obstructive FIC
An episode of obstructive FIC should be treated as a medical emergency. The affected cat may have life-threatening acidosis, dehydration, hyperkalaemia or hypocalcaemia and may be anaemic due to blood loss in the urinary tract7. Stabilisation is required prior to further diagnostic work-up or procedures (Panel 1).
Once the patient is stabilised, abdominal radiographs can be performed to assess the cause of obstruction and urethral patency restored by catheterisation under sedation or general anaesthesia. Opioids and benzodiazepines are the sedative agents of choice (Figure 3).
Buprenorphine (20µg/kg IV) is a safe, effective opioid and provides mild sedation, analgesia and anaesthetic-sparing effects. Benzodiazepines – for example, midazolam 0.1mg/ kg to 0.2mg/kg IV – cause muscle relaxation, with little effect on the cardiovascular system and can be combined with an opioid to provide sedation or co-administered at induction, to reduce the amount of induction agent required12. Benzodiazepines are most effective in very young, old or sick patients, as otherwise they may cause excitation12.
Propofol is a useful induction agent, as small amounts can be administered slowly IV to effect. Alpha-2-agonists are contraindicated, due to their cardiovascular effects and suppression of endogenous insulin production (therefore permitting hyperglycaemia)12. Once sedated or anaesthetised, catheterisation can be performed to relieve urethral obstruction (Panel 2).
Considerable debate exists over whether to suture the urinary catheter in place for 24 to 48 hours after relieving obstruction. Although this aids urine drainage, some argue it may perpetuate urethral spasm and inflammation13.
Following removal of the obstruction, monitoring of fluid input and output is important as postobstructive diuresis may be marked (resulting in hypovolaemia/dehydration) and urethral spasm may result in dysuria14. Fluid therapy, with a balanced electrolyte solution, is usually adequate for rehydration.
Analgesia – for example, buprenorphine 20µg/kg IV every six to eight hours – and antispasmodics, such as the alpha-1-antagonists prazosin (0.2mg/cat to 1.0mg/cat orally, every 12 hours) or phenoxybenzamine (0.5mg/kg to 1.0mg/ kg orally, every 12 hours) may be used, in an attempt to relieve urethral spasm14. In rare cases, significant post-obstructive blood loss can occur in the urinary tract, resulting in profound anaemia, which may require a blood transfusion (Figure 4)14.
Although urethral catheterisation is typically required to relieve obstruction, a recent small-scale study described a protocol without catheterisation. It consisted of sedation and analgesia (acepromazine 0.25mg IM or 2.5mg orally every eight hours, buprenorphine 0.075mg orally every eight hours and medetomidine 0.1mg IM every 24 hours) and decompressive cystocentesis and SC administration of fluids as needed15. Cats were also placed in a quiet, dark environment to minimise stress15.
This protocol may be an option for cases with a functional blockage only (no evidence of urolithiasis or urethral plugs) and financial constraints that preclude catheterisation. However, acepromazine and medetomidine should only be used once the patient is stable (neither hypovolaemic nor dehydrated) and the complication rate in a larger cohort of patients is yet to be determined.
• Environmental management
Environmental modification to reduce stress is recommended for cats with FIC. A thorough environmental history should be taken at initial presentation and all resources – for example, food, water and litter trays – for all cats in the household addressed and multimodal environmental modifications (MEMO) suggested (Table 1)2,16.
Modifications may be more successfully achieved if changes are made gradually in a stepwise fashion and progress is regularly reviewed at follow-up appointments with the same veterinarian or nurse2.
• Nutritional management
Increasing dietary water intake as nutritional management may decrease the concentration of substances in the urine that act as an irritant to the bladder mucosa8. Water intake can be increased by feeding wet rather than dry food, multiple meals per day rather than a single meal and by adding fluid – for example, stock – to food17.
Additional dietary factors hypothesised to play a role in FIC management include protein concentration and digest- ibility, mineral concentrations (sodium, chlorine, calcium, phosphorus and magnesium), acidifiers and alkalinising agents, vitamin B6 and omega-3 fatty acids18.
• Pheromones
Synthetic feline facial pheromone may reduce stress in cats by affecting the limbic system and hypothalamus8. It is commercially available as a spray or diffuser and its use in a study of 12 cats with FIC demonstrated a trend for cats in the pheromone-treated group to have fewer episodes of cystitis and fewer days with clinical signs of cystitis19.
This suggests pheromone therapy may be useful if there is inadequate response to MEMO and dietary modification alone.
• Neuropharmacological agents
Amitriptyline is a tricyclic antidepressant that has been recommended for use in feline patients with FIC, as it is used in human patients for management of interstitial cystitis8.
Short-term (seven day) treatment with amitriptyline is not recommended as, in one study, it led to an increase in the speed of recurrence and frequency of episodes of lower urinary tract signs20. However, there is some evidence that long term treatment may be useful if there has been no positive response to MEMO and dietary change21.
• Nutraceuticals
In FIC patients, defects in the glycosaminoglycan layer lining the bladder may allow irritants – for example, calcium or potassium ions – to come into contact with the bladder mucosa2. Therefore, glycosaminoglycans (GAGs) such as glucosamine, pentosan sulphate and chondroitin sulphate are often used to treat FIC.
Studies to date, using oral glucosamine, suggest GAGs may be useful as an adjunctive agent to MEMO and dietary modification, but there is insufficient evidence to support their use as a sole therapeutic agent22.
• Antimicrobials
Antibiotics have historically been recommended for FIC management, but are only indicated if bacteria are present on urine culture.
• Surgery: a salvage procedure
Perineal urethrostomy is a surgical procedure involving creation of a shorter urethra with a wide stoma less likely to obstruct. It is a salvage procedure indicated for FIC cases, characterised by recurrent obstruction, despite medical management23. It is important to recognise this procedure does not correct underlying FIC and clinical signs will continue postoperatively if FIC is not treated13.
FIC is a common, but incompletely understood, condition, diagnosed by exclusion of other causes of FLUTD. The goals of management are to control acute episodes and reduce the severity and frequency of clinical signs in the long term. Acute obstructive episodes require intensive stabilisation, prior to relief of obstruction.
Long-term management involves environmental modification and conversion to a wet diet. Feline facial pheromones, glycosaminoglycans and amitriptyline may be used as an adjunct for longterm management.
• Please note some of the drugs ment ioned wi thin this article are used under the cascade.
1. Record baseline vital parameters
Demeanour, heart rate, peripheral pulse quality.
2. Take baseline blood work
Urea, creatinine, PCV, total solids, electrolytes, blood gases if available.
3. Place IV catheter and start fluid therapy
Neither balanced electrolyte solutions containing potassium, for example, Hartmann’s solution (5mmol/L K+), nor acidic solutions, for example, 0.9 per cent saline (pH 5.0), are ideal for hyperkalaemic and acidotic patients. However, recent evidence suggests both types of crystalloid solution are safe and effective11.
4. Treat hyperkalaemia if severely elevated (more than 8mmol/L)
To promote intracellular transport of potassium, administer either:
• Soluble insulin (0.5 units/kg IV) and dextrose (2g per unit of insulin; half given as an IV bolus following insulin and the remainder administered IV over four to six hours).
• Sodium bicarbonate (0.3 × base deficit (mEq) × bodyweight (kg); one third to half given as an IV bolus over 15 minutes and the remainder administered IV over four to six hours).
To provide short-term protection against hyperkalaemic cardiotoxicity, administer:
• Calcium gluconate (50mg/kg to 100mg/kg slowly IV over five to 10 minutes, while monitoring the patient’s electrocardiagram (ECG).
5. Treat acidosis if blood pH is less than 7.2, with evidence of cardiovascular compromise and adequate respiratory function
Administer sodium bicarbonate IV, as above.
6. Provide analgesia
For example, buprenorphine 20ìg/kg IV, and perform decompressive cystocentesis to reduce pressure across the bladder wall7.
7. Regularly recheck
Vital parameters, electrolytes and blood gases, to assess response to therapy.
1. Gently massage the urethral tip between a thumb and forefinger, to encourage dislodgement of urethral plugs from the distal urethral lumen.
2. Connect a well-lubricated urinary catheter (preferably openended) to an intravenous extension set and 10ml syringe filled with sterile saline.
3. Flush through the extension set and urinary catheter with sterile saline, to evacuate air.
4. Exteriorise the penis caudally and dorsally, to eliminate the distal urethral flexure.
5. Carefully introduce the tip of the urinary catheter into the urethral opening.
6. Slowly and gently advance the urinary catheter along the urethra, while flushing with sterile saline. Walpole’s solution should never be used for this purpose, as it is highly irritant to the urethra and bladder and causes severe inflammation.
7. As the urethral plug is disrupted, the catheter should be advanced until its tip is in the bladder.
8. The syringe can then be used to remove urine from the bladder.
Figure 1a. Plain lateral radiograph of the caudal abdomen of a cat with two radiodense uroliths in the urethra – caudal to the ischium – and three smaller radiodense bladder calculi. A urinary catheter is in place.
Photo: AHT.
Figure 1b. Plain lateral radiograph of the caudal abdomen of a cat with ureteral obstruction, which presented with mixed clinical signs of upper and lower urinary tract disease.
Photo: AHT.
Figure 2. Contrast urethrocystogram showing bladder wall thickening in a cat with FIC.
Photo: AHT.
Figure 3. Sedation with buprenorphine and co-induction with propofol and midazolam is a suggested anaesthetic protocol for blocked cats.
Photo: AHT.
Mayank Seth
Job TitleStephanie Jayson
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