Urolithiasis In SA

Question 1

What is the difference between uroliths and crystals?

Answer 1

One is macroscopic, one is microscopic

Question 2

What type of crystals are found in normal young cats with concentrated urine?

Answer 2

STRUVITE

Question 3

When do crystals form?

Answer 3

When urine is supersaturated

Question 4

How does increasing concentration affect the stability of urine?

Answer 4

Stable -> meta stable -> unstable

Question 5

What occurs when urine is unstable?

Answer 5

Nucleation - formation of a new crystal

Question 6

Compare the concentration of solute required for Nucleation to growth when a nidus is present

Answer 6

Concentration of solute required is higher for nucleation

Question 7

Is it possible to dissolve crystals?

Answer 7

Yes, for some if the concentration of solute can be reduced sufficiently

Question 8

What clinical signs may be associated with cystoliths ?

Answer 8

Dysuria, pollakiuria, haematuria

Inappropriate urination

Generally not palpable

Question 9

What clinical signs may be associated with urethroliths?

Answer 9

Abdominal discomfort 
Poor to no urine stream 
Licking of genital area
Obstruction and post renal azotaemia 
Enlarged painful bladder
May be palpable per rectum or at base of os penis

Question 10

What clinical signs may be associated with nephroliths and ureteroliths ?

Answer 10

Asymptomatic if non obstructive
Pyelonephritis - can be nidus for infection
Renal failure - if bilateral obstruction or infection
Renal colic

Question 11

What can cause kidney abnormalities on palpation?

Answer 11

Hydronephrosis or irregularity

Question 12

What type of stone are UTIs associated with?

Answer 12

Struvite

Question 13

What is the only reliable way of assessing uroliths?

Answer 13

Quantitative analysis with lab

X-ray diffraction provides detailed analysis of mineral composition

Question 14

What type of stone is not usually amenable to dissolution?

Answer 14

Calcium oxalate

Question 15

What treatments should you consider for renal and ureteral stones?

Answer 15

Surgical removal 
Urinary bypass
Dietary dissolution IF non obstructed 
Benign neglect 
Extra-corporal shock wave lithotripsy

Question 16

Why should surgical removal be carefully considered in renal and ureteral stones ?

Answer 16

Will damage nephrons and decrease GFR

Question 17

What species should you not perform extra-corporal shock wave lithotripsy on?

What can you? When?

Answer 17

CATS

Dogs - referral procedure, rare

Question 18

How should you attempt to treat urethroliths?

Answer 18

Retrograde flush into bladder and perform cystotomy if surgery is required

Question 19

What uroliths are amenable to medical dissolution

Answer 19

Struvite
Urate
Cystine

Question 20

When would you consider medical management ?

Answer 20

No obstruction
No contraindications to diet therapy
Urolith composition amenable

Question 21

How do you medically manage uroliths?

Answer 21

Decrease concentration of urine by INCREASING water intake

Decrease quantity of CALCULOGENIC crystalloids with diet or drug therapy

Increase solubility of salts by changing the pH

Treat any predisposing cause

Question 22

What is urohydropropulsion?

Answer 22

SEDATED - cats + sm dog
Fill bladder with saline 
Position so urethra vertical 
Agitate 
Allow stones to settle 
Initiate voiding 
Continue pressure to keep brisk flow
Peri-procedural antibiotics