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The Beat Goes On - Report on Research Studying Heart Disturbances In Horses

posted by Horse Owner Today    |   January 11, 2012 14:08

Normal heart rhythm and sounds in a horse are difficult to define because of the fascinating array of strange sounds and rhythms which can be found in apparently healthy animals and which change with exercise.  Also, even when sounds or rhythms do reflect heart problems, most horse owners will not notice signs, until there is an inability to perform work at a level previously achieved successfully, when the horse shows an unusual tendency to tire.

 

Owners of performance horses understand the economic impact of a horse that can no longer work, or in the worst-case scenario, where sudden loss becomes a serious issue.  University of Guelph researcher Dr Physick-Sheard states, “After safety issues and welfare issues are discussed there is still a need to put an economic value on the horse, which is decided by the client”.  One aspect of research Dr. Physick-Sheard and Dr. Kim McGurrin look at is atrial fibrillation, the most common clinically significant rhythm disturbance horses can have.   An arrhythmia is technically defined as an abnormal heart rhythm, however, irregular heart rhythm is commonplace in horses and the endeavor to define normal, continues to be a complex and fascinating journey.  A completely steady rhythm can be considered abnormal.

 

Before a diagnosis of heart problems can be made, Dr. Physick-Sheard explains, a logical process where the client is asked the history of the horse (breed, use, how long it has been in training) is followed before conducting a general physical examination.  Future use would also be discussed before deciding on diagnostics.  An Electrocardiogram may be the next step to determine the heart’s rhythm and possibly an ultrasound to look at how efficiently the muscle and valves work.  They look for enlargement or abnormal structure in the heart and check for normal blood flow around the valves. 

 

Dr. Physick-Sheard describes two types of rhythm disturbance that can be found:   

 

1.  Benign variations on normal (mostly involving the top part of the heart).

 

2. Ventricular rhythm disturbances, which can be serious and even life threatening.

 When found, they look first for problems outside the heart, disturbances in homoeostasis, which involves keeping the environment around cells constant:  dehydration, electrolyte and acid base imbalance.  Under these circumstances secondary arrhythmias are often detected.  Situations where the cardiac problem is primary are rare but sometimes serious.

 

McGurrin and Physick-Sheard have had enormous success treating arrhythmia with transvenous electrical cardioversion. The response rate has been 100%!  Electrodes are placed into the heart to deliver an electric shock, while the horse is under anesthesia, to convert the rhythm to normal. 

 

Dr. McGurrin and Dr. Physick-Sheard developed this technique before their first Standardbred track study, where they collected heart rhythm data during racing using an electrocardiogram.  Dr. Physick-Sheard explains how the technology works, “The heart is a bag of muscle, a slave pump which does what the system tells it, contracting at a rate that reflects the body’s needs. The heart gives off an electrical signal when it contracts which reaches the skin and can be detected by the electrocardiogram (ECG).  This is then used to monitor heart rhythm.”

 

Dr. Physick-Sheard has developed specialized equipment and software for the current intensive Thoroughbred study, which he is hoping will give more insights into causes of sudden death.

 

Research funding has been provided by Equine Guelph, Grayson Jockey Club Foundation and OMAFRA.

 

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Story by:  Jackie Bellamy

 

Web Link: http://www.equineguelph.ca/news/index.php?content=315

 

Links to the Utube Videos:

Report on Research: http://www.youtube.com/watch?v=fXI3Q0pMl34&lr=1&feature=mhee

Help for Horse Owners:

http://www.youtube.com/equineguelphuofg#p/c/595FECA446307F6A/0/BQSdkSsbmE8

Marathon Surgery Saves Mare's Life

posted by Horse Owner Today    |   January 6, 2012 10:37

An 11-year-old Arab mare defies the odds and survives more than 12 hours in surgery to remove one side of her jaw along with a grapefruit-sized, cancerous tumour.

 When Dr. James Carmalt examined the grey Arabian mare named Noor for the first time at the WCVM’s Veterinary Medical Centre last fall, the first thing that surprised him about the horse was her body condition.

“You could tell that Mr. Abidi (her caregiver) had been working hard to ensure that she had the right type of feed available and had managed to keep her weight on,” explains Carmalt, an equine surgeon at the WCVM. “She looked like a relatively normal horse — other than having this huge growth on the side of her face.”  

The grapefruit-sized growth, about 26 centimetres (cm) in width and 20 cm in height, had been developing on the back curve of the horse’s right jaw ever since an accident occurred when she was two or three years old. Earlier in 2010, Syed Abidi found the disfigured mare on a farm in B.C. while searching for a specialized bloodline of Arab breeding stock.

He knew time was running out for the tough little horse that had managed to adapt and survive for so many years: “I saw a horse that needed help and I went for it,” says Abidi.

With the owners’ consent, Abidi brought the horse to Dr. Ryan Shoemaker of Delaney Veterinary Services in Sherwood Park, Alta. But after the cancer diagnosis was confirmed, Shoemaker referred the case to Carmalt.

“I think Dr. Shoemaker knows that if I could concentrate on equine head and teeth cases for the rest of my career, I would be a very happy man,” jokes Carmalt. “But he also knows that we’ve got many willing hands to help with post-operative care — something that’s very difficult to manage in private practice.”
“She wanted to go for it”

After several phone and email discussions, Abidi and Noor met Carmalt for the first time in November 2010. For two days, Noor underwent a battery of tests at the WCVM: a physical examination, a full mouth oral examination, an endoscopy of her upper airway and both of her guttural pouches, and radiographs of her skull and chest.

“Everything culminated with the CT scans. That allowed us to do a 3-D reconstruction of the tumour and that’s when we found out how large and invasive it really was,” explains Carmalt, adding that the tests showed no metastasis in the horse’s lungs.

Then Noor went home for three weeks — giving Abidi time to consider the risks and expense of the experimental procedure. “We talked at length about the risks. We also made a lot of effort to discuss the potential endpoints beforehand because we all wanted to consider the horse’s welfare,” says Carmalt.

“If she reached endpoint X or she suddenly decided that she had enough, we agreed that I would be the ultimate decision maker about euthanasia.”

 “Dr. Carmalt and I — we think alike. We’re cautiously optimistic. We understand the risks involved but we’re willing to continue moving forward,” adds Abidi. “More than a dozen times, I was told to just put her down because it was too risky and too much money. But Noor is a smart horse — she let me know that she wanted to go for it.”

In the meantime, Carmalt prepared for a surgery that, based on veterinary literature, had never been done before. Besides experimenting on equine cadavers, Carmalt consulted with colleagues in the U.S. “Almost universally, the answer was, ‘Good luck with that,’” says Carmalt, who found invaluable advice closer to home.

Dr. Kathleen Linn is one of the WCVM’s small animal surgical specialists and routinely removes parts of the jaw in dogs diagnosed with cancer. But the surgeons had to plan for a different scenario with Noor. Instead of performing most of the surgery inside the mouth (the practice used for canine patients), the surgical team — consisting of Carmalt, Linn and Drs. Imma Roquet and Holly Sparks — would need to do most of the procedure from the outside because of the tight space inside the horse’s mouth.
“Like digging out a fossil”

 Once Noor was prepped for surgery, the team inserted a tube through a tracheotomy in her neck. As well, they isolated her carotid artery in case a large bleed occurred and they needed to block the artery — an emergency procedure that slows down blood loss and buys time for surgeons.

The team used that emergency option four times during Noor’s marathon surgery that lasted for more than 12 hours. The procedure began with a 30 cm incision just below the tempomandibular joint (TMJ), curving around the bottom of the jaw to the front. The surgeons dissected their way down to the bone, lifting the tenuous tissues and facial nerves up like a flap until they could see the bone.

“Then we made a horizontal cut just below the TMJ at the top and a vertical cut between the second and third cheek tooth and lifted out the jaw,” describes Carmalt. “And that left us with a massive hole.”

The actual removal of the jaw bone took less than 15 minutes. What took time was cutting through the complex web of blood vessels — a process that Carmalt compares to digging out a fossil with painstaking care. “With a tumour, there’s a massive amount of new blood vessels. We knew where the major blood vessels were but there were so many vessels involved in the tumour — it was a whole entity on its own.”

After removing Noor’s swollen lymph nodes and any cancerous tissue, the surgical team began the laborious process of closing the hole with five layers of tissue and skin. Two catheters were left in the hole: one suctioned fluid out of the closed area while the other was a “soaker” catheter that allowed clinicians to put painkilling drugs directly into the wound.

As expected, Noor was wobbly in the recovery room but showed no ill effects of being under general anesthesia for so long. Within six hours, her post-surgery care team was offering her a variety of feed to choose from.
Horizontal to vertical chewing

When surgeons remove one side of a dog’s jaw, the animal can still chew its food up and down on the opposite side of its mouth. “But horses chew their feed horizontally so they need both sides to chew,” explains Carmalt. “We had no idea what Noor was going to do, but in retrospect, I should have held more stock in my physical exam and the CT findings.”

What the CT scan had shown was that Noor’s cheek tooth angles were flat as opposed to 15 degrees — the normal angle found in horses. Carmalt and his team eventually realized that Noor had already adapted to her disability before the surgery, learning how to chew vertically.

Three days after the procedure, Noor was eating enough to maintain her body weight. The rest of her three-week stay went relatively smoothly — thanks to the hard work of veterinary students who cared for Noor around the clock.

Noor returned home to Alberta just before Christmas. Since then, her recovery has had its challenges especially because of the harsh winter conditions on the Prairies. Noor also had some trouble eating because of dental issues, requiring Abidi to try different feeding options for her.

But the fact that Noor is alive and now has the chance to live a relatively normal life is still a miracle to Abidi who credits Carmalt for taking the chance on Noor. While he acknowledges that it was costly to save Noor, Abidi points out that he also spent the money to give the WCVM surgical team a chance.

“Dr. Carmalt told me it was a great learning experience for everyone involved. And by talking about this surgery, maybe others will read about it and be more confident about taking on these kinds of challenging cases in the future.”

For veterinary students, Carmalt says Noor’s case emphasizes the importance of referring cases to teaching centres like the WCVM once they’re in practice. It has also led to some intensive discussions about medical ethics at the veterinary college.

“From an ethical standpoint, I think we were very close to the edge with this horse. And if she hadn’t recovered as quickly as she did, we may have wished we hadn’t done it,” admits Carmalt. “I think as long as you have the welfare of the horse absolutely paramount and you aren’t swayed by the financial and emotional investments of the client, then I think you can try. You just need to know when to stop.”  

Besides Noor’s strong will to survive and adapt, the other factor in the mare’s favour was Abidi: “He had already put in a massive amount of work to care for Noor plus he was willing to invest thousands of dollars in her surgery. After all that, I knew he wasn’t going to back off on his care,” says Carmalt. “He was in it for the long haul.”

 

Reprinted with permission from Horse Health Lines, publication for the Western College of Veterinary Medicine’s Equine Health Research Fund. Visit www.ehrf.usask.ca to sign up for our e-newsletter.