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Date:   28 May, 2009
Focus: Small animals - dogs, cats, hamsters & rabbits.
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Toa Payoh Vets Clinical Research
Making veterinary surgery alive
to a veterinary student studying in Australia
using real case studies and pictures

What is Canine Retrograde Urohydropropulsion? An incredible story?
Dr Sing Kong Yuen, BVMS (Glasgow), MRCVS
Case written: May 26, 2009
Case updated: May 28, 2009

It was such a fine evening as the sun rays cast a golden glow onto the trees. I had completed my day's work and looked forward to relaxation. I thought I would just drop into a Veterinary Surgery of my old friend to see what type of spay hook my peer had bought from Australia. His Veterinary Technician had said they were excellent hooks.

There are many makes of spay hooks and I am always on the look out for the best type which is well designed and easy to use. As if there are such instruments but one never knows.

Canine uroliths, Chihuahua, Male, 10 years. Toa Payoh Vets "Do you want to see a bladder stone surgery?" the Vet Technician whom I knew for more than 10 years asked me as I was leafing through the various pages of skin diseases in dogs in the several text books at this Surgery. A veterinarian on duty was performing this surgery. I really wanted to enjoy this beautiful sunset and the fresh air. "Well, I could just see a while and go off," I thought this was a run-of-the-mill urolith case.

However, this case was an exceptionally challenging case due to the fact that there were 3 places where uroliths had formed or got stuck.

From my view of the X-ray, the main problem was the urolith (Y) stuck at the bend of the urethra, between the bladder and the penis. The stones at X and Z could be removed by cystostomy (cutting open the bladder) and urethrostomy (cutting open the urethra behind the os penis). But God had placed one large stone which cannot be removed by cutting as the stone was inside the urethral lumen inaccessible to surgical blades.

How to get this stone at Y out?  There would be 2 ways:
1. Use a rigid catheter to push the stone into the bladder. The stone (Y) would then be removed via the bladder incision. However there would be traumatic damage to the urethra tissues as the rigid catheter forces its way trying to dislodge the large stone (Y). This result in profuse of bleeding and that will not be good for the dog. The success, in my opinion, is not be guaranteed. This large stone was the cause of urinary obstruction. The bladder had distended to over 30X its normal size and was going to rupture in this case.

2. Retrograde urohydropropulsion. What this method means is to flush normal saline via the penile orifice into the urethra to flush out the stone at Y into the bladder. In theory, this sounded easy. In practice, this could be hellish.

1. General Anaesthesia.
The 10-year-old male Chihuahua was put on an IV drip. It weighed 2.5 kg. Injectable anaesthesia was used. 0.2 ml of 20% xylazine and 0.05 ml of ketamine IV was given. The dog went into general anaesthesia. Topping up with small amounts of Zoletil 50 IV given via the IV drip at 0.1 ml was used when necessary.

2. Surgery. 
2.1 Ventral recumbency. The bladder had distended to near the umbilical area. A 4-cm midline incision cranial to the penile orifice was made. The bladder was exposed.

2.2  Cystocentesis. A 21-G needle with a 10-ml syringe was inserted midway between the vortex and neck of the bladder, on the ventral side. Over 100 ml urine was extracted. The bladder was now half full.

2.3. The assistant used his two hands to press inwards on the lower abdomen, ventrally and from laterally. The bladder popped out of the skin incision.

2.4 Cystotomy. The bladder was incised 1.5 cm where the needle was inserted. The stones were removed from the bladder using forceps and flushing. This was the easy part of surgery.

2.5 Retrograde urohydropropulsion. A 10-ml syringe with normal saline would not be effective as the pressure would be too low. A 30-ml syringe was used. The rigid catheter (not flexible one) was used. It got stuck around 10 cm after passage as there were stones behind the os penis.

Canine Retrograde Uropropulsion. Chihuhua. 10 years. Male. Toa Payoh VetsThe penile orifice was closed by the thumb and forefinger of the assistant while the saline was forced in. This was repeated a few times. Still there was no stone or saline coming out from the bladder. There were 4 stones behind the os penis and these were big stones.

"Remove the stones behind the os penis by cutting open the urethra (urethrostomy) behind the os penis" the assistant recommended. There seemed to be no headway. I was the observer and therefore needed not sweat this out. So, should urethrostomy behind the os penis to remove the 4 stones easily be done?

As an observer, it was easy for me to comment: "Even if you remove the 4 stones by cutting the urethra behind the os penis, you still cannot remove the large stone (Y) as it is deep inside the urethra. You can use the rigid catheter to push it out but there will be a lot of bleeding. Try flushing again. How about rectal pressure?"

Rectal pressure meant putting a finger inside the rectum and then onto the urethra. This would help to increase the pressure of the saline to flush out the stone (Y) when the finger is released after another 30 ml of saline was injected via the catheter. Now, this method was not practical as the dog was a small breed and in any case, it was on ventral recumbency.

Retrograde urohydropropulsion was tried several times again. The saline came out via the penile orifice each time the assistant tried. He used a bigger diameter catheter to push the 4 stones. There seemed to be some progress.

"How about massaging the urethra behind the os penis?" I suggested. As an observer, I was not so much stressed out as this was not my case. So I could make such a suggestion. The Vet Technician massaged the urethra with his fingers. Up and down. Then he resumed flushing.

I don't know whether my suggestion really worked or not. One stone got flushed out of the urethra into the bladder and was picked out. More urohydropropulsion. 3 more stones came out. There were of similar sizes. "These are from behind the os penis," the Vet stated as their sizes were similar to those seen on the X-ray. "There is now the big stone still stuck."

By this time, the smaller rigid catheter was used and it went further into the urethra and appeared out in the bladder incision. The team was elated but silently happy. We still had this one last "diamond" inside. If only it was a real diamond. What should be done now?

As an observer, I could advise: "Push the catheter in and out of the bladder to roll the large stone loose and out of the bend of the urethra."  The Vet did that a few times. Then he commenced urohydropropulsion. The smaller rigid catheter could move in and out of the bladder but not stone was seen. 

Was there any hope? The Vet flushed normal saline from the opening at the bladder neck into the urethra. "Will this method be pushing the large stone into the urethra?" I asked him. He did once only. He continued flushing saline via the penile orifice and clamping the orifice shut with his thumb and forefinger to increase the pressure.

In what seemed like an eternity, the large stone rolled out into the bladder. The stress was over for the team. And for me too. An observer could also be stressed when things do not move on smoothly. I was happy for the team and for the dog.

I described this case in great detail to share my observations with veterinary students who must study urohydropropulsion - a big word reading the procedure from dull veterinary surgery text books. I hope this real life case may be of use to the 4th and 5th year veterinary students who need to pass examinations.

This case was great team work. The dog went home to a very happy owner. Instead of dying from bladder rupture and kidney failure. I missed a fine evening but this was a most interesting case if one was not the operating veterinary surgeon. 

NOTE TO DOG OWNERS. Get your dog treated early and promptly when he had difficulty in passing urine and not wait till it is too late. Not every surgery has such a successful outcome as this case. The large stone is stuck at the bend of the urethra was due to a long time in seeking veterinary treatment.

It was an extremely difficult case to remove such a large stone as this part of the urethra is not accessible by surgery.

In retrospective review of the case in May 28, 2009, I wonder how the 4 stones stuck behind the os penis could be flushed out past the large stone (Y) one by one. The large stone (Y) was the last to be flushed out.  The urethra lumen would need to be at least the combined diameter of the smaller and large stone at the bend of the urethra. In theory, this was NOT possible. This seem to be an incredible story. If I had not been present, I would have said that this is a tall tale. Out of this world. Did God give a hand to the mere mortals and the old dog?

In real life, many things cannot be explained. Fact is stranger than fiction? Seeing is believing and therefore I will not expect the reader to believe this story.      

Rectal pressure is applied for dogs standing. The bladder is not incised yet. Stones are flushed into the bladder using retrograde urohydropropulsion. In such cases, the bladder must not be fully distended. The use of rectal pressure is to increase the pressure, using 30-ml syringe and normal saline to flush the stones behind the os penis into the bladder. Obviously, the stones must be smaller than in this case. As the stones get into the bladder, a cystostomy is then done. Alternatively, the small stones are dissolved using dietary methods and other medication without the need for surgery.  

Injectable anaesthesia.  0.2 ml of 20% xylazine and 0.05 ml of ketamine 100mg/ml IV, separate syringes, were given to the 2.5 kg dog. It provided excellent general anaesthesia in this case for some 15 minutes but topping up with 0.1 ml Zoletil 50 IV  was easy. Topping up was to effect. See other information at: Animal Shelter Medicine.

I use isoflurane gas anaesthesia but injectable anaesthesia is nowadays excellent and safe for dogs too. Topping up is necessary.  Each vet has his own preferences.  I hope the vet students understand what is the meaning of retrograde urohydropropulsion now.

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