Vet Blog
06/17/09
A recent article in The Economist caught my eye.
Medical technology: A new, low-cost design for an artificial heart takes its inspiration from an unusual source—the cockroach
EVOLUTION has favoured cockroaches above human beings, at least when it comes to the functioning of the heart. A cockroach’s heart will continue to beat even when one of its chambers has failed; in similar circumstances, a man will die. Now a team led by Sujoy Guha of the Indian Institute of Technology, Kharagpur, has created an artificial human heart based on a cockroach’s, which they believe will be unusually robust and affordable.
A cockroach’s heart is a tube that runs the length of its body. It has 13 chambers, linked like a string of sausages. As each chamber contracts, the blood within is pumped to a higher pressure. Each successive chamber increases the pressure. A human
or feline or canine
heart, by contrast, has four chambers. Two of these pump blood to the lungs, where it picks up oxygen, then the other two pump this oxygenated blood throughout the body. One of these four chambers—the left ventricle—contracts most strongly to pressurise the blood.
The artificial hearts developed so far have mostly mimicked human ones. The first devices, developed in the 1950s and 1960s, were large machines placed on trolleys next to the patient and attached by tubes. Modern artificial hearts are less cumbersome, but they are still rather unwieldy because they use compressed air to pump the blood and are powered by heavy batteries. They are used temporarily, usually for a few days or weeks, until a real heart is available for transplant.
Instead of trying to mimic the action of the left ventricle, Dr Guha’s design uses a multi-step approach borrowed from the cockroach. His device, made from plastic and titanium, is the same size as a human heart but with five chambers arranged like the layers of an onion. Each chamber acts in succession to increase the pressure of the blood. The contraction of each chamber is controlled by a motor driven by bulky batteries. The artificial heart is being tested on goats, with human trials scheduled for next year. If these are successful, the device could be on the market in three to five years.
The multi-step approach makes this artificial heart much cheaper to build than those that use compressed air to pump the blood. Dr Guha says it would cost $2,000-2,500.
Add in the costs of protection from liability lawsuits, and I’ll bet the new artificial heart will come in for $50,000 or so.
This article nearly inspired me to make another 30 year prediction for the record: that artificial hearts will be available for cats and dogs by 2039. But, although I am excited by advances in artificial heart technology, I am not going to make that prediction.
Instead, I predict that within 30 years stem cell technology will allow veterinarians to grow new hearts for cats and dogs from their own tissues.
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05/18/09
 Heart disease in young cats seem to be increasing, at least based on anecdotal reports I’m receiving. I’ve heard of several instances of seemingly healthy cats between the ages of 2 and 5 dying suddenly, or requiring euthanasia, from heart attacks or related conditions. Is this a recognized trend, and do we know what causes heart disease in cats, especially in cats so young? How can we protect our cats from heart disease?
Melanie
North CA
Heart disease in cats generally is caused by a syndrome called cardiomyopathy. The muscle of the heart does not function properly in cats with the syndrome. This can lead to heart failure or other serious complications including sudden death.
Feline heart disease is much less common now than several decades ago. That is because one of the causes of heart disease in cats was discovered to be a dietary insufficiency of an amino acid called taurine. Taurine is now routinely added to most feline diets.
Hereditary causes are involved in most cases of feline heart disease in current times. Breeds such as Maine Coons and Persians have known predispositions to cardiomyopathy. However, the syndrome can strike any breed of cat. It also affects non-purebred individuals.
Modern genetics hopefully will dramatically reduce the incidence of feline cardiomyopathy in the near future. I, for one, would be very happy never to see another case of it. The disease is not highly treatable and it frequently strikes young cats who otherwise would have most of their lives ahead of them.
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03/18/09
 Why does my Yorkie sometimes make this goose like
sound, like he can’t catch his breath or has something
stuck up his nose?
Charmaine
Mendocino, CA
Dogs generally make goose-like noises when they cough. Since foreign objects lodged in the nose usually cause sneezing, it isn’t likely that your Yorkie has something stuck up his nose.
In young dogs, kennel cough (also known as infectious tracheobronchitis) is a common cause of goose-like honking. Kennel cough is a contagious disease that almost never is life-threatening. Most cases are self-limiting (which means that they resolve on their own without treatment).
In older small dogs such as Yorkshire Terriers, a syndrome called collapsing trachea frequently leads to a honking cough. Collapsing trachea occurs when the firm rings supporting the wind pipe begin to weaken. It leads to a chronic tickle in the throat.
Heart disease is another common cause of coughing in older small dogs. Yorkies sometimes develop leaky heart valves as they age. This causes fluid to build up in the lungs which leads to coughing.
Several less common causes of coughing also are possible. These include, among others, pneumonia, bronchitis and heartworm. Visit my website for more information, or, better yet, go to the vet for a proper diagnosis.
Photo: Minnie at the beach. No sign of coughing.
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08/14/08
 The evidence keeps rolling in. Pets are good for people.
I was quite excited when Discovery CME, an organization that offers online continuing education for physicians, confused me for an MD and sent me their schedule. Among their offerings is a program that seemed right up my alley. The program is entitled “Pets and People: The Power of the Health Connection.” You can watch it online if you have a high speed connection.
The program is intended to be educational material for human physicians. I found this surprising (and, on some levels, disturbing) because the narration and theme of the program make it seem much more like an after-school special than a serious scientific work.
However, it makes solid points.
Animal companionship leads to decreased stress in humans. This can help to prevent heart disease.
Dogs and cats can provide exceptional support for humans with disabilities ranging from blindness to quadriplegia to autism and beyond.
Dog walking promotes weight loss, muscle strength, and cardiovascular health.
Therapy dogs help with the emotional and physical recovery of patients in hospitals, assisted care facilities, and other institutions.
Pets provide valuable (and often critical) emotional support for humans with serious diseases such as cancer.
The above list does not even come close to being complete. If you want to read more about the ways in which having a pet benefits human health, check out the humanhealth tag on this blog. As well, you can find more information The Power of Paws, a website dedicated to spreading the word.
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07/24/08
 Heart disease is very common in dogs. Most cases of heart disease in dogs are hereditary, rather than acquired. This means that, unlike in humans, obesity and a sedentary lifestyle are not major causes of heart disease in dogs (although obesity exacerbates heart disease in all species).
There are two major forms of heart disease in dogs. Small breeds are prone to valve disease. Valve disease causes the blood to flow incorrectly through the heart and lungs. Large breeds are prone to cardiomyopathy, a syndrome in which the muscles of the heart lose the ability to function normally. Either condition can lead to heart failure and death.
The mainstays of diagnosing canine heart disease have been physical exam, evaluation for irregular heart sounds known as murmurs, X-rays and echocardiography (ultrasound of the heart). Echocardiography is especially effective at diagnosing heart problems. However, in many cases the problem is not detected until it has been present for a very long time. And, as with all medical conditions, treatment for canine heart disease is most effective if the problem is detected early.
Fortunately, a paper in the May 15, 2008 Journal of the American Veterinary Medical Association describes a new test that may soon become available to identify dogs with heart disease. The test would be a blood test that could be performed routinely on at-risk breeds.
The test would involve measuring the level of a peptide (a very small protein) in the blood. A recent study demonstrated that blood levels of the peptide reliably predict the presence and severity of heart disease in dogs.
It may be several years before any test involving the peptide is available for veterinarians. However, it is encouraging to know that in the future it may be possible to diagnose heart disease earlier and more easily in our canine friends.
The paper discussed in this post is Oyama, et al J Am Vet Med Assoc 2008;232:1496-1503
Image credit: Heikenwaelder Hugo. Image licensing information: CC
Image confession: it is a human heart. But the canine heart is anatomically similar.
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