Sunday, June 29, 2014



I was visiting Dr Aung of the Royal Asia Veterinary Surgery when I saw him treating a case relevant to my presentation for this Seminar.

The owner of this 4-year-old intact male cat in Yangon had her cat treated twice by Vet 1, but dysuria occurred a 2nd time. She consulted Dr Aung of Royal Asia Veterinary Surgery and the treatment process is as follows:
0:32 - 1:05  Cat sedated. Urethra catheterisation. No obtruction. Urine flows out.
1:23 - 1:32  Dipstick to check pH, blood, leucocytes and others
2:32 - 3:18  Fed dry food? I asked.
3:40 - 3:52  Microscopic exam for urine crystals? I asked.
4: 13 - 4:24 Suck out bladder sand and debri using the catheter and syringe
4:55 - 5:14  Treated by Vet 1 seven days ago for 2nd time, but still dysuria.
                    "Don't eat dry food." I commented.
7:05 - 8: 02  At the 2nd recurrence, did Vet 1 check for any bladder or kidney stones? X-ray done?
Vet 1 had prescribed Royal Canin S/O dry and some antibiotics.

8:19 - 9:05   Suture catheter to prepuce two sides laterally. So it would not fall off.
9:20 - 10:22  Did Vet 1 irrigate bladder after flushing?
10:45 - 11:48   Normal saline to irrigate bladder. Hospitalised 3 days. E-collar. 

Recurring urolithiasis is a complex  problem to resolve. The owner doctor-hops to find a solution and previous treatment by the other vet may be hard to obtain.

In this case, in retrospective review, I have the following questions:

1.  What was the composition of the uroliths in the urine or urethral plugs as seen by the Vet 1?
2.  Did the first vet do a survey radiograph and urinalysis? Ultrasonography? Blood test?
3. What was the urinary pH on the first visit?
4. Vet 1 had prescribed dry Royal Canine Urinary S/O for this cat and so the pH was acidic when tested by Dr Aung. Was the urethral plug or urolith confirmed struvites? Or oxalate or urate stones?  Just recommending the S/O diet without chemical analysis of the urethral plug or uroliths or urine crystals may lead to failure of treatment. Hence the cat or dog keeps having dysuria.
5. Were there stones in the kidneys?  

This is a "Be Kind To Pets" Veterinary Educational Video titled: 
 DIAGNOSIS & TREATMENT OF UROLITHIASIS IN DOGS AND CATS produced by Dr Sing Kong Yuen, BVMS (Glasgow), MRCVS. It is presented at the "Recent Advances in Veterinary Practice No.3. Myanmar Veterinary Association, July 5, 2014".

Urolithiasis is the formation of urinary stones (uroliths) within the urinary tract (kidneys, ureter, bladder and urethra). The outflow of urine is obstructed, leading to inflammation, septicaemia, shock and death. 

The 3 most common uroliths found in the canine cases in Toa Payoh Vets, Singapore are struvites (magnesium ammonium phosphate), calcium oxalate and urates. Cystine and silica urolithiasis are uncommon.  In feline cases, infection-induced struvites are the most common type seen but oxalate urolithiasis do occur in cats.


1. A correct diagnosis is important. History.  Dietary type, onset, recurrence. Clinical signs. Important ones are dysuria, haematuria and pollakuria.
2. Bladder palpation (large distended bladder, stones inside the bladder and crepitus). Abdominal pain or discomfort. Palpation of a likely “bladder” stone is not reliable and it is best to get radiography or ultrasonography performed to confirm its presence.

TIP. For some owners who want the cheapest medical costs, I had removed bladder stones after bladder palpation without X-rays. I do not recommend this method. The bladder “stone” palpated may not be present  during surgery.  In any case, write in your case record under AMA (Against Medical Advice), that the owner does not want radiography as advised, to defend yourself against allegations of negligence.

3. Vaginal discharge (mucopurulent) may be seen with chronic lower urinary tract infections in dogs.

4. Blood test. CBC/Biochemistry. Leucocytosis, neutrophilia and thrombocytopenia indicate septicaemia and a poor prognosis.  High serum BUN and creatinine will point to kidney damage. Inform the owner about the poor prognosis if relevant, before surgery to remove the bladder stones.   

Always advise a blood test to screen the health of the dog or cat and possible kidney damage to determine the anaesthetic risks and prognosis.  Leucocytosis, neutrophilia and thrombocytopenia indicate septicaemia and a poorer prognosis.    

5. Imaging
5.1 Survey radiography shows radio-dense stones such as struvites, calcium oxalate and silica.  Cystine and urate uroliths are radiolucent and the vet may need to perform contrast cystography or ultrasonography. 

5.2 Air-contrast radiography.  I prefer to inject 20 ml of air into the canine bladder via the urinary catheter, to show clearly the number of bladder stones.  In female dogs, the use of a vaginal speculum or finger to guide the urinary catheter into the bladder will require more patience, time and practice as compared to the male dog’s urethral catherisation. I note that many vets do not catheterise females.  


TIP. Some vets perform only the lateral view to reduce medical costs. Two views must be done as radio-dense objects in the lateral view may not be located within the bladder.

TIP. If no radio-dense uroliths are seen on survey radiography, many vets diagnose that there is no urolithiasis. They don’t do contrast cystography or ultrasonography.  Perform routinely urinalysis which may reveal the presence of cystine or urates, both of which are radio-lucent.

TIP. I encountered cases where some vets just X-ray the bladder and urethra area. They miss radiography of the kidney area where uroliths may also be present. It is important to X-ray the abdomen and pelvis as uroliths may be present in the kidneys, ureters, bladder and urethra.

Air-contrast survey radiography.  I inject 20-30 ml of air into the empty bladder before X-raying. Good outlines of the stones and the bladder wall and numbers of stones can be seen. 

5.2 Ultrasonography shows the thickened bladder wall (chronic cystitis), location, number and size of uroliths. It will show the presence of bladder wall tumours which may be the cause of haematuria. Normal bladder wall cannot be detected by ultrasonography.

6. Urinalysis. I have heard from one client that her vet consider urinalysis unnecessary if surgery is to be done. Urinary pH and SG, presence of blood, bacteria and crystals can be useful in the post-surgical management and prevention of recurrence of urolithiasis. .

TIP. Some vets state that the absence of urinary crystals in the urine mean that no uroliths are present. This is not true as stones can be present without crystals in the urine.

7. Bacterial urinary culture and antibiotic sensitivity test are rarely done to reduce medical costs.

8. Chemical analysis of the uroliths.  Chemical analysis of the stones removed by surgery or passed out in the urine is one procedure that all vets should not forget. Some clients do not want to pay the cost of analysis and this should be recorded in the case notes under AMA (Against Medical Advice).  An Australian vet at his talk in 2013 mentioned about an Australian vet who just removed the stones and not send them for analysis even though there was recurrence of urolithiasis. This vet lost a loyal client to him.

In Singapore, Hills’ Science Diet provides a free stone analysis to be done by the University of Minnesota. I send the stones to the local laboratory for analysis as results come back much earlier.

9. Client Education & Informed Consent Form.
9.1. Outflow obstruction caused by urolithiasis is a medical emergency. Prognosis depends on the health of the dog as shown in the blood test results of CBC/Biochemistry as well as physical examination.

9.2  Informed consent for anaesthesia and surgery explaining the high risks involved esp. for old dogs. This is important as there have been litigation against Singapore surgeons who have not fully explained the risks of anaesthesia and surgery.

9.3  An estimated amount of medical costs must be given to the owner before the surgery. A bladder stone removal surgery and anaesthesia in small breeds cost around $800 in Toa Payoh Vets in 2014, excluding supportive therapy and in-patient nursing.  

1. Immediate I/V fluid therapy, antibiotics and pain-killers for 1-2 days. I usually give Hartmann’s, dextrose and amino acids, baytril and spasmogesic IV. The dog or cat is an in-patient.

11.1   I use 25-50% of the calculated dosage I/V for sedation/induction depending on the health of the dog. Then I intubate and maintain with isoflurane + oxygen anaesthesia. If the dog is very weak and lethargic, I use entirely isoflurane + O2 anaesthesia and find this to be very effective and safe.

11.2 My calculated dosage is as follows: For a young 10-kg dog, Domitor + Ketamine IV = 0.4 ml + 0.5 ml respectively.

11.3 For very old (over 10 years) dogs and/or in poor health, I use only isoflurane + oxygen gas.

11.4  Clipping and cleaning to be done before sedation outside the operating room reduce anaesthetic time and risks.

11.5  For cats, I use xylazine + ketamine at 0.1 ml + 0.4 ml IM for a 2-kg cat sedation, topping up with isoflurane + oxygen gas when necessary.

Outflow obstruction due to stones obstructing the urethra is a common situation in male dogs. 

Briefly, the procedures after diagnosis of urolithiasis are as follows: Sedation, urethra catheterization, syringe normal saline to flush the stones into the bladder (use 30-ml syringe instead of 10-ml) and remove all stones from the bladder surgery. It may be very difficult to flush larger urethral stones into the bladder (voiding urohydropropulsion) when they are lodged at the bend of the urethra. I know of one case of recurring urolithiasis where the vet used a hard catheter and rupture the urethra, leaking urine into the skin  

Some vets prefer incising the urethra behind the os penis to remove the stones and open up the bladder to remove the bladder stones. I had one case of the owner wanting to euthanase the male dog that had a urethral opening performed by another vet, as the dogs keeps dribbling urine from this opening, soiling the apartment floor. Voiding urohydropropulsion (flushing uroliths back into the bladder) might have prevented euthanasia in this case.

MOST VETS WILL access the bladder from the lateral side of the penis. I have tried one surgical approach from the cranial part of the prepuce as shown in the following images.

This is a most common problem in male neutered cats seen at Toa Payoh Vets. Sedation, urethral catherisation to unblock the urethra followed by bladder irrigation several times normal saline till the bladder is cleared of blood and debri.

I stitch up the catheter to the prepuce, put the cat on an Elizabeth collar and ward the cat for 2-3 days. I removed the stitched catheter before sending the cat home.

Some vets send the cat home on the same day and in one case, the cat just bite out the urinary catheter despite the wearing of the Elizabeth collar. It is important that the vet do urinalysis and teach the client how to switch over to the canned Prescription Diet. Follow up by phone calls is necessary but sometimes not done by the busy vet. The owner must be warned about recurrence if he does not comply with medical (not able to give antibiotics)  and dietary instructions (feeding same dry food).

In recurrence, survey radiography and more detailed tests to check other types of uroliths such as calcium oxalate may be present, instead of struvites, may need to be done. 

3. FELINE LOWER URINARY TRACT DISEASEThe causes are varied. I had a case where the 5-year-old male cat was stressed leading to dysuria only when the owners shifted to a new house. This cat had recurring dysuria and died some months later during treatment for dysuria by Vet 3.  The wife was much distressed.  I advised getting a female cat and there is no dysuria problem so far as it seems that male cats get this FLUTD more frequently.

14.1 Empty the full bladder before surgery. In male dogs, I may inflate the bladder with 20 ml of normal saline to enable it to be easily accessed.  A case of bladder stone removal in a cat, similar to that in the dog, is shown below:


TIP. The full bladder may be just below the skin. If the vet is not careful, the bladder may be cut spilling urine into the peritoneum.
TIP. Be careful. Avoid contamination of the peritoneum with urine and small uroliths by packing the surgical area next to the bladder with many sterile swabs.  

  4.1 Sutures. For closure of the bladder wall, I usually use two layers of continuous inverting suture if the bladder wall is thickened by inflammation. I use 3/0 braided absorbable sutures (Polysorb) in all my bladder closures. My associate vet, Dr Daniel prefers the 3/0 monofilament absorbable sutures (Monosyn). 

4.2  I use Anti-sedan IM to reverse and abolish the effects of Domitor sedation in cases where the dog is still not conscious after the surgery. The dog is usually awake within 5 minutes of the injection.

4.3   Post-op Nursing. The dog is hospitalised around 3 days to lower the medical costs. She goes home with antibiotics for another 10 days and an Elizabeth collar. Tolfedine pain-killers are given for the first 4 days.

Nephrolithiasis is rarely seen at Toa Payoh Vets and I have no experience of the surgery to remove kidney stones. I had two cases in 2013/2014 (IMAGES). One involved a Miniature Schnauzer with recurring cystourolithiasis. Another was an old Poodle. Both owners did not want to spend money on further tests and the dogs died soon.  A senior vet had done the rare case and said that the dog felt great pain post-surgery. Also, he said that the kidney was swollen and infected (nephritis). An Australian vet who gave a talk in 2013 said that he would operate only if 70% of the kidney tissues are still functional.      

TIP. Shock wave lithotripsy to blast and break up kidney stones is too expensive for almost all  dogs and cats.


The surgical approach is similar as for cats 

Ureteroscopy and lithotripsy may be used to remove the ureteric stones in people. I have not encountered cases of ureteral stones in dogs and cats. 


1.  Presently, only struvite stones can be dissolved/prevented using prescription diet that acidifies the urine, e.g. Hills’ S/D and C/D or Royal Canin Urinary S/O (no pork ingredients important for certain religions).  Use acidifying tablets as an alternative.  

In my opinion, bigger struvite stones of over 1 cm diameter cannot be dissolved using dietary means although the Minnesota Urolith Center had mentioned this could be done in 2-3 months. Many clients don’t have the time to monitor the progress and do more survey radiographs. Surgery is usually the best way.  

2.  One of my clients did not want the bladder stones in her Miniature Schnauzer removed by surgery and the dog had one episode of urethral obstruction but is OK now without surgery. Another client had a male Pekinese keeps peeing out stones for many months as the owner did not want any radiography or urinalysis (IMAGE). He had to rush the dog as he developed urethral obstruction after midnight.  He died during attempts to unblock the bladder by the emergency vet who was “blamed” for the death.   

3.  Non-compliance by clients. Many Singapore clients do not know how to get the dog or cat to eat the prescription diet and so give up. The vet has to advise on how to do it. Mix 10% of the new diet and increase to 100% in 2-4 weeks. No other food or dog/cat treats.

4.  Feed canned food only.  No more dry food if possible. Feed home-cooked food. No more treats or sharing other pet’s dry food.

5.  Get the dog or cat to drink more water e.g. more exercise, add ice.

6. Urine monitoring every month for the first 3 months so as to confirm that the prescription diet is effective in acidifying the urine and to check for bacteria and crystals in the urine.

7. Survey radiography every 3-monthly so that small stones can be removed by retrograde urohydropropulsion (eliminate stones via the catheter). None of my clients in the past 30 years bother to adopt this advice!  

Air contrast survey radiography

8. Diet management to prevent stone formation. Some will just buy the Prescription Diet regularly and that is all they do. Only struvite stones can be dissolved by dietary management. The others cannot be done this way and stone formation are prevented by feeding the appropriate diet. 


1.  Practise evidence-based medicine as younger clients are better educated and have high expectations. Some 10 years ago, in one case, the dog kept vomiting and died despite being spayed. I did not do the blood test to check for kidney damage as the owner wanted the cheapest medical cost. Her family members sent mass e-mails to their friends who forwarded to friends reaching everyone in Singapore, advising them not to consult me. There were strangers and a doctor who phoned me to let me know. Nowadays, they use Facebook or pet forums to voice their grievances against the vet. 

2. AMA (Against Medical Advice). Nowadays, I give the client a written record that he does not want blood tests, X-rays or procedures as advised by me. I have the written evidence in case of litigation or complaint. In computerized records, there is the allegation of falsifying evidence by deleting the earlier record but vets using manual records need to keep proper records to protect their reputation.

3.  Update your knowledge by research and continuing education

 Much more detailed research and advices on the diagnosis, treatment and prevention can be obtained from the website of the Minnesota Urolith Center, University of Minnesota
e.g. urate urolithiasis in cats is at:

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