Dr Sing Kong Yuen, BVMS (Glasgow), MRCVS
RECURRENT UROLITHIASIS - CALCIUM PHOSPHATE URINARY STONES
When a dog has urinary stones again, the following will be the Standard Operating Procedures (SOP) at Toa Payoh Vets to provide the highest standard of care. This SOP defends the vet during allegations of negligence litigation or complaint if the dog has another episode of recurrent urolithiasis.
1. HISTORY. Record all vaccinations done and dates and by whom. Do not forget to do so. Record your analysis of why the dog had recurrent urolithiasisa. In this case study of the Shih Tzu with 13 calcium phosphate urinary stones, the dog came to Toa Payoh Vets for recurrent urolithiasis and I took charge of this case which was operated by Vet 1.
Vet 1 had not done stone analysis, did not advise (in writing) on post-operation prevention and follow-through tests which would permit non-surgical treatment (e.g. voiding urohydropropulsion and urinary catheterisation when small stones are detected via X-rays 3-monthly). Could it also be some metabolic disorders of the parathyroid glands as calcium phosphate is quite rare in dogs?
2. GENERAL EXAMINATION. Demeanour. Weight, rectal temperature, pulse and respiratory rate. Abdominal pain, gas in the GIT and other observations.
3. DETAILED EXAMINATION. Urine test, blood test, radiography (calcium phosphate isradio-dense, check kidneys for calcium phosphate), ultrasonography (possible in calcium phosphate) and calculi analysis. There may be a case for veterinary negligence if the tests has not been advised or done. The advices must be recorded in the case sheets clearly.
4. TREATMENT. According to symptoms. IV, SC or oral fluid therapy depending on dehydration situation. Antibiotics to treat UTI. Urinary catheterisation to relieve urethral obstruction.
The vet in charge of the case is responsible for details of time, amount and other information will be recorded in the hospitalisation sheet.
5. COMMUNICATIONS WITH THE OWNER IN WRITING. A veterinary report explaining the significance of the tests and case must be given to the owner on discharge/death of the puppy. It is best to keep the owner informed daily of the health of the dog. Such phone calls must be recorded in the medical case files.
6. RECORD AMA (Against Medical Advice) the owner's rejection of advices of the test in your medical record. Failure to do so implies that the vet has not advised at all in cases of litigation/complaint. As Singapore is becoming a litigious society, I advise that the highest standard of care to be given at all times. An example of a case done by me is down shown in the images.
TOA PAYOH VETS CASE STUDY BY DR SING
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.
TOA PAYOH VETS webpage will be written later:
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