Feline urolithiasis

Question 1

Feline Lower Urinary Tract Disease (FLUTD), causes

Answer 1

• urolithiasis (25%) struvite, calcium oxalate
• urethral plugs (20%)
• idiopathic (55%): noninfectious inflammatory LUTD, clinical signs subside in 5-7 days without treatment up to 92% of cases, diagnosis of exclusion

Question 2

FLUTD factors

Answer 2

• urine pH (acidifying foods)
• dietary mineral intake
• dry food intake/decreased water consumption
• BSC (obesity)
• sedentary lifestyle/indoor lifestyle
• bacterial/viral/fungal infection
• neuroendocrine response (cats are stressed, don’t release cortisol correctly)
• unknown

Question 3

FLUTD clinical signs

Answer 3

• stranguria/dysuria
• pollakiuria
• micturition in unusual places (periuria)
• hematuria +/- pyuria
• anuria, urethral obstruction
• +/- crystalluria

Question 4

Gender, age, breed, concurrent disease with FLUTD

Answer 4

• males most prevalent, also common in overweight females; urethral obstruction most commonly in males
• 1-10 yrs old; mineral type in immature cats is usually struvite
• burmese, persian, himalayan breeds (Ca oxalate)
• UTI less common compared to dogs

Question 5

What are the common types of stones in cats?

Answer 5

struvites and calcium oxalate

Question 6

Underlying etiologies of FLUTD

Answer 6

• infection, inflammation
• neoplasia, anatomic abnormalities (can be due to trauma)
• mucus (matrix) plugs
• crystals and/or uroliths
• crystalline (matrix) plugs

Question 7

Matrix mechanism

Answer 7

matrix remains after dissolution of crystalline component of plug (mucoprotein=’glue’)
- +/- oversaturated urine: mineral component of the plug

Question 8

Dietary components/management: struvites

Answer 8

• form in alkaline urine
• result of increased protein and minerals (Mg, P, Ca)
• diets to control struvite are urine acidifying and low in Mg, P
• sterile struvites are common

Question 9

Dietary components/management: calcium oxalate

Answer 9

• usually form in an acidic to neutral urine
• alterations in Ca and oxalate absorption/excretion
• acidifying diets low in Mg fed long term promote Ca oxalate formation
• chronic acidification

Question 10

Feeding method impact on urolith formation

Answer 10

• free choice: minimizes post-prandial alkaline tide (release of bicarbonate during gastric acid release)
• meal fed, there is an increase in the tide which increases the risk of struvite formation

Question 11

Dietary management goals for struvites

Answer 11

• dissolution
• promote diuresis
• prevention
• some diets are approved for life-long feeding while others are short term

Question 12

Dietary management goals for Ca oxalate

Answer 12

• prevention

- promote the production of urine that is metastable for Ca oxalate

Question 13

Dietary management of idiopathic cystitis

Answer 13

• feed canned formulation of diet
• often resolves within 7-10 days, regardless of feeding plan
• environmental enrichment important to prevent recurrence (food, water, litter box, scratching objects, resting areas, windows and climbing opportunities

Question 14

Dietary management: overzealous acidification

Answer 14

• increased incidence of Ca oxalates
• acidemia mobilizes Ca and P from bone, hypercalciuria
• Vit B deficiency (experimental in kittens) resulting in hyperoxaluria and oxalate nephrocalcinosis

Question 15

Compound uroliths

Answer 15

• mechanical removal

- minimize recurrence of minerals composing the nucleus

Question 16

Failure of dissolution/prevention

Answer 16

• owner non-compliant with recommended diet and/or antibiotic regimes
• antibiotic not effective in control of UTI
• urolith/urinary precipitates are different type than originally diagnosed
• outer shell of uroliths is different composition from the core
• uroliths and nephroliths both presesent