The Royal Veterinary College has carried out the first ever open-heart surgery to treat a stenotic tricuspid valve in a dog.

The three-year-old Labrador, Mabel, suffered from congenital tricuspid dysplasia. She was referred to cardiology specialists at RVC Small Animal Referrals where her tricuspid valve was found to be completely fused in the middle, with just two very small openings for her blood to flow through. 

In a procedure that took a little over an hour, the RVC team examined and worked on the valve. The College reports that Mabel’s surgery was a success and her stenosis was relieved.

Mabel was subsequently found to have a moderate amount of regurgitation into the right atrial chamber, but after a few more days of additional monitoring at the RVC she was able to return home. 

The surgery was carried out by Professor of Small Animal Surgery Dan Brockman at the Queen Mother Hospital for Animals. He was assisted by a team of RVC specialists to provide pre and post-operative care, including a perfusionist, a team of three anaesthetists, two surgery nurses, three surgeons and a cardiology veterinary specialist-in-training. In addition, Professor of Veterinary Cardiology Virginia Luis Fuentes and veterinary specialist-in-training Dr Rosie Payne were members of the Cardiology Service’s investigation into Mabel’s condition.

RVC students were also involved in the Mabel’s initial examinations at the hospital, providing them with an insight into the procedure. The examinations included cardiac ultrasound using the newest generation of cardiac ultrasound equipment, which is able to capture 3D and 4D images. The new ultrasound scanner was funded in part by the RVC’s charity, the Animal Care Trust. 

After the surgery, the emergency and critical care (ECC) team and the Cardiology Service took over Mabel’s care, with Professor Brockman remaining involved. This saw up to four senior ECC clinicians, a number of veterinary specialists-in-training and half a dozen highly trained ECC technicians working in shifts around the clock to care for Mabel and ensure a good recovery.  

According to the RVC, there have been previous attempts by veterinary surgeons to open stenotic valves with balloon valvuloplasty. However, because it is very difficult to tear the stenotic valve, this approach has not proved very successful. There is also a high risk when putting canines onto bypass. Canines have fragile blood vessels, and cannulae need to be inserted into several of these vessels, creating a danger that a major vessel tears. 

Commenting on why the RVC team decided to perform this procedure at this point, and on Mabel, Dan said: "Lots of things fed into this decision. First and foremost, we had a patient whose pathology made surgery the best solution. I explained to the owner and was very honest that this procedure would be really breaking new ground. Based on what the human paediatric cardiac surgeons will do, and our limited experience of balloon-valvuloplasty suggests this is the best approach for these dogs

"The operation itself is risky, much worse than most other operations. In our hands, for this type of disease, we have about an 80% chance of getting them through the procedure. The owner has to gamble what life the dog has left against the promise of a more normal quality of life and life-span following the operation."

In relation to Mabel’s prognosis if the surgery had not been undertaken, Professor Luis Fuentes said: "It is likely that the signs of right-sided heart failure would have been more difficult to control. Her ability to exercise would have become less and less, and she would have also been at risk of having abnormal heart rhythms associated with the enlargement of the right atrium. Generally we expect them to develop more and more signs as the disease progresses. These are difficult cases to manage on a long-term basis with drugs. Her life expectancy would have been substantially reduced.

"I thought Mabel was almost a perfect candidate to have the procedure here as Dan has a lot of experience replacing tricuspid valves in dogs with tricuspid dysplasia. In those cases there is usually leaking, but Mabel’s case was unusual in that she has minimal leaking and she was most affected by the stenosis. That means you may not have to implant any additional valve structure."

Speaking two weeks after the operation, owner Annabelle Meek, from Melton Mowbray, said: "Mabel has just come back in from wandering around the perimeter of my garden for the first time since before the operation. It’s more than half an acre and she has been ambling around happily following a scent.

"I would like to thank absolutely everybody. It’s been an enormous team effort on all sides. Every single person I met at the RVC, from the man on the gate to all the hospital staff, was so friendly. After she came home Dan Brockman phoned me every day to see how she was doing. The RVC should be very proud of what they have done for Mabel."

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