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Date:   22 February, 2013  
Focus: Small animals - dogs, cats, hamsters, guinea pigs & rabbits
Prevention of recurring oxalate or urate stones  
Dr Sing Kong Yuen, BVMS (Glasgow), MRCVS
Date:   22 February, 2013 
Be Kind To Pets
Veterinary Education
Project 2010-0129
Wed Feb 20, 2013

A review of the case operated by Dr Vanessa twice for oxalate bladder stones in May 2011 and September 2012. I audited the case and on Sep 26, 2012, I asked Dr Vanessa as to what follow up she had done to prevent a 3rd recurrence. She said she had advised U/D and had sms the calcium oxalate stone analysis results. Many owners will just ignore the advices till another recurrence and another operation or euthanasia of the poor old dog. I took the trouble to write to the owners to let them know the preventive measures as I don't want a recurrence too, although recurrence is in the interest of the practice. An extra effort had to be made to follow up and vets usually don't have the time to do the hard sell of prescription diets in the interest of the canine patient.

The father came to buy 12 cans of U/D again for the cocker spaniel, male, 11 years old today. "How's the dog?" I asked him as he had been feeding this U/D since Oct 5, 2012 when he bought 3 cans and came whenever he ran out of the stock. Seldom do I encounter such a disciplined owner as many Singaporean owners tend to forget about feeding the relevant diet to prevent bladder stone recurrence.

"His body condition is much better compared to previous times when he sheds hair all the time and has dry skin flakes," the father surprised me with this feedback. "I thought it was normal for dogs to shed hairs."

"How do you know this dog sheds hairs previously?" I asked. "Does he drink lots of water?"

"Hairs scatter all over the floor of the apartment and so this shows he has been losing hair. He drinks water too."

This was good news but it is too early to tell whether the dog will have recurrence of bladder stones. The 2nd episode occurred 16 months after the first cystotomy operation to remove the stones. It is only 5 months after the 2nd cystotomy.

From my case records, on Nov 1, 2012, the father told me that after the first operation, he had fed the dog dry food. After the 2nd operation, he fed cheap canned food and meat and yet the stones recurred. Now, he is satisfied with the U/D.


Many owners don't know that urine tests and X-rays are still necessary as part of the prevention of recurring urolithiasis as typical in this case. Feeding of prescription diet is just one aspect.

Monitoring includes urine tests and X-rays of the bladder. This should be 1-2 months for the first 6 months and thereafter, if negative results, 2-4 monthly. Very rarely do any Singaporean dog owner comply with this advice and there is not much the vet can do.

Monitoring and urine tests which show small stones can easily be treated with a process called urohydropropulsion in which the catheter is inserted into the bladder and the small stones are sucked out easily. These stones are analysed in case they are of different composition.

This case shows that the education of the dog owner with recurring urolithiasis is an uphill task and there are so many family members involved. Who in the family will have time to do the 1-2 monthly monitoring? The young ones are busy with their work and personalised life. The older members may not have the motivation to spare the time to get the dog tested.

Today, I reminded the father that he has to send the urine for analysis of crystals. He said: "Yes, you have given me the bottle to collect the urine." There is not much I can do. Urine test will monitor the urine pH, bacteria and other results as well as urine crystals and monthly urine tests will be more economical than another surgery. But Singaporeans seem to be time-pressed and so that is the culture. I don't expect any urine sample from this father as that is his personal matter.

P.S Monitoring of Urine to prevent or treat recurring urolithiasis: Absence of oxalate crystals in the urine does not mean no oxalate stones as can be seen in the 2 urine tests taken prior to bladder stone removal surgery as follows:

May 24, 2011 Urine pH 7.0, SG 1.028, Blood 4+, WBC 10, RBC >2250, Bacteria 3+, Crystals Calcium oxalate occasional

Aug 28, 2012 Urine pH 7.0, SG 1.029, Blood 4+, WBC >2250, RBC >2250, Bacteria 3+, Crystals Nil

From my case records, on Nov 1, 2012, the father told me that after the first operation, he had fed the dog dry food. After the 2nd operation, he fed cheap canned food and meat and yet the stones recurred.

Updates will be on this webpage:

Calcium oxalate urinary stones are radiodense. Take X-rays. Toa Payoh VetsA case of oxalate stones:

More info at: Dogs or Cats
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