831. The Shih Tzu has reccurent urolithiasis. 13 calcium phosphate stones

Chinese New Year Eve 4.56pm
Jan 22, 2012

PATIENT: Shih Tzu, Male, 8 years, not neutered
Around 12 months ago, Vet 1 removed many "urinary stones" but no stone analysis or other tests or follow throughs were advised. I don't know the reasons and will not speculate.

It is important to confirm the nature of the stones and a stone or calculi analysis should have been done and must be done to confirm the diagnosis. This must be recorded in the case sheet and advices of prevention of recurrence be given and recorded.

The dog recently had urethral obstruction. 13 urinary stones on X-ray were removed. Stone analysis done showed pure calcium phosphate crystals and urine tests showed bacterial infection UTI.

DIAGNOSIS: Calcium phosphate urolithiasis

CASE MANAGEMENT AT TOA PAYOH VETS

14.1.12 Calculi analysis by the NUH Dept of Lab Medicine.
Calcium stone positive, phosphate stones positive. Negative for stones of oxalate, urate, magnesium, cystine, ammonia and bicarbonate.

8.2.11 Blood test. SGPT/ALT increased, SGOT/AST increased, Urea increased 8.9 (4.2-6.3). Platelet 522 (200-500)/ Blood calcium 1.99 (1.5-3.60) is normal.

13.12.12 Urine test. ph=7, SG 1.012, Protein ++, Blood ++++, WBC 468, RBC 25, Bacteria +++. There is UTI and possibly kidney involvement. X-rays - any stones in the kidneys? Not seen. No crystals seen in the urine but this does NOT mean that the dog does not have stones when urine test is negative as in this case.

Radiography at 3-monthly intervals post-op would have picked up the stones when they were small but very rarely do Singaporean owners bother to do this. When stones are small, they can be "sucked" out using the urinary catheter and voiding urohydropropulsion. That is the reason for radiography.

X-ray in this case showed 13 radiodense uroliths. Calcium phosphate stones are radiodense.

TREATMENT
1. Medical dissolution using prescription diets. This is not possible for calcium phosphate stones.

2. Surgical removal. Done.
3. Non-surgical methods like voiding urohydropropulsion and aspiration into a urinary catheter not possible. 13 big stones with 2/13 stuck in the penile urethra.

4. Non-surgical method. Lithotripsy is not available in Singapore.
5. Metabolic disorder. Correction of hyperparathyroidism or other causes of hypercalcemia should minimise further urolith formation.

HOW TO PREVENT RECURRENCE?
1. Post-op radiography every 3 monthly is the best advice.
2. Urine test monthly to check for bacterial infection (UTI).

REFERENCE: The 5-min veterinary consult - Tiley Smith

1. PURE calcium phosphate uroliths are usually associated with metabolic disorders such as primary hyperparathyroidsim, rental tubular acidosis and excessive dietary calcium and phosphorus. This dog was fed on dry dog food.

2. A higher % of calcium phosphate uroliths are found in the kidneys than in the urinary bladder

OTHER LAB TESTS
1. Calculi analysis is necessary and was done.
2. Serum concentrations of parathyroid hormone,parathyroid hormone-related peptide
and hydroxycholecalciferol may be useful.

PREVENTION/AVOIDANCE
1. Hill's Prescription Diet U/D is formulated to reduce calcium extretion, is phosphorus-restricted and reduces formation of concentrated urine.
2. Canned diets are more effective than dry diets in preventing recurrence due to high moisture content
3. Avoid excessive acidfication or alkanisation of urine.

INTERESTING INFO
Hill's book recommends treatment of bacterial UTI and then give C/D

FOLLOW UP
1. X-ray after surgery to verify complete urolith removal is essential. This was not done as surgical removal of 13 stones were presented.
2. Abdominal radiography or ultrasonography every 3 months to detect early recurrence and prevent repeat surgery (e.g. using non-surgical methods to remove easily by voiding urohydropropulsion or catheter retrieval.

TP 16915
Op Date: Jan 12, 2012
Surgeon: Associate vet

A. Sedation injection 3.11 pm
Skin prep, Isoflurane gas
B. Skin incision 3.38pm
C. Skin stitched up 4.11 pm

B-A = 27 minutes. Dog was ferocious and therefore prep had to be done after sedation
C-B = 33 minutes. This is acceptable time taken for cystotomy for an experienced vet. All 13 stones were inside the bladder and accounted for. Therefore there was no need to do urethrostomy. The stones must have been flushed back into the bladder under anaesthesia by Vet 1 during the after midnight visit.

Blood test by Vet 1 - Significant findings, 12.40am Jan 12, 2012
MCV high 79 (60-77)
WBC high 26 (5.5 -17)
NEU high 21 (2-12)
MONO high 3 (0.3-2)
BASO high 0.16 (0-1)
PLT high 660 (175-500)

BUN high 31 (7-27)
ALKP high 233 (23-212)
K high 6.5 (3.5-5.8)

Jan 23, 2012. Chinese New Year.
I am keeping an eye on the follow through of this case. So far, the owner said she is busy and had not come down to get the CD canned diet.