Urolithiasis Flashcards
What urine type predisposes to urolith formation?
Supersaturated/concentrated urine
What is the order of formation of a urolith?
- Supersaturation
- Precipitation of a nucleus
- Crystal growth and aggregation
- Calculus retention
T/F: If the animal has crystals in its urine that means it has uroliths?
False- it means that the urine is supersaturated
T/F: Crystals may form in stored urine.
True- always check urine soon after sampling
T/F: Radiographs are always diagnostic or urolithiasis.
False- Only CaOx and Struvite show up
Is nutritional therapy always helpful for treating uroliths?
No
What is voiding urohydropropultion?
Filling the bladder and aggressively emptying it manually
What is required with voiding voiding urohydropropultion?
Small stone size- must be able to fit through the urethra
What kind of animal does voiding urohydropropultion work best on?
Female dogs- can take 5-15mm
What is the objective of retrograde urohydropropulsion?
Push uroliths obstructing the urethra back into the bladder where they can be dealt with easier with sx or dissolved
What are the different urolith types?
- Struvite
- Calcium oxalate
- Cystine
- Urate
- Silicate
- Mixed/compound
What is the composition of struvite crystals?
Magnesium ammonium phosphate hexahydrate
Where are struvite crystals usually found?
Mainly lower tract, occasionally upper
What are struvite crystals typically associated with in dogs?
Urinary tract infections with urease producing bacteria
May also be breed related- mini schnauzers, shitzu, mini poodle, cocker spaniels, lhasa apso
What are struvite crystals typically associated with in cats?
Diet
What do struvite uroliths look like?
Big, smooth, radiodense (less radiodense than CaOx)
What is the therapy of choice for struvite uroliths/crystalluria?
Dietary
Lower pH and dilute urine
What is a worry with dietary therapy in struvite cystals?
Predisposing to CaOx
Which hills diet treats and which prevents struvite crystals?
Treatment- s/d
Prevention- c/d
What animals are most prone of calcium oxalate crystals?
Male dogs
What kinds of things can predispose to calcium oxalate crystals?
Acidifying diets
Obesity
Hypercalciuria
Breeds
What do calcium oxalate crystals look like?
Small, very radiodense
Spiney and rarely cause obstruction
What are the treatments for calcium oxalate crystals?
Therapy for hypercalcemia
Surgery, lithotripsy, cystoscopy
How do you prevent calcium oxalate crystals?
High pater diet, potassium citrate, thazide diuretics, avoid vitamens C and D
What is potassium citrate?
Binding agent for dietary calcium
Why do most animals get ammonium urate and xanthine (purine) crystals?
Hepatic disease (PSS or cirrhosis) or genetic tubular defects
What breeds are predisposed to urate crystals?
Dalmatians, and black russian terrier
What predisposes certain breeds to urate crystals?
Decreased uptake of uric acid from hepatocytes to recycle properly to allantoin
What urine pH favors urate and xanthine crystal formation?
Low pH
T/F: Urate crystals can be diagnosed with radiography.
False- they are radiolucent
What therapy should be followed for urate stones?
Dietary dissolution- low protein, increase pH ( potassium citrate and sodium bicarb)
What breed are xanthine oxidase inhibitors used in?
Dalmatians- decreases uric acid production
Die effects- hyper sensitivity, toxic epidermal necrolysis
What disease process is supportive of a diagnosis of urate stones?
Hepatic dysfunction
What is the percentage of cystine calculi?
1-8%
What breeds are predisposed to cystine calculi?
Australian cattle dogs, dachshunds, newfoundlands, bulldogs
What is the pathopysiology of cystine calculi formation?
Defective tubular carrier proteins that are supposed to reabsorb cystine
T/F: Cystine calculi are radioopaque.
True- but are very hard to see on radiographs so not clinically useful if suspected
What drugs are used to treat cystine calculi?
Thiol drugs- big risks, must talk to owner first
What can be done to the diet to help manage cystine calculi?
Alkalinize the urine and low protein diet
What condition is usually implicated in calcium phosphate uroliths?
Primary hyperparathyroidism
What diets will result in silica uroliths?
Using plant as primary protein sources (rice and soybean), cheap diets with improper protein
