Canine heart disease
Heart disease has long been one of the main causes of human illness and death in America and western countries worldwide. Sadly, it is usually not until a dog has been diagnosed with heart disease that their owner’s realize that this is a problem that regularly affects our canine companions as well. Canine heart disease comes in many shapes and forms; it can affect young puppies to geriatric dogs and are definitely more common in certain dog breeds, whilst other breeds seem to develop heart disease only very rarely.
The heart and its function
The heart is a complex muscular organ that houses four chambers with four valves that are all ultimately responsible for distributing the oxygenated blood from the lungs, to the entire body and then collecting the deoxygenated blood back from the body to send back to the lungs for re-oxygenation. For this to occur, the heart needs to beat at the correct rate and force. Heart disease can occur due to a vast majority of reasons, but in every case the net result is that blood is not distributed around the body effectively or adequately. There can be problems with the valves of the heart (eg. Mitral regurgitation – commonly affecting small breed dogs), there can be problems with the muscles of the heart (eg. DCM or Dilated Cardiomyopathy – commonly affecting large breed dogs), there can also be congenital problems (where the heart does not develop properly in young puppies) and everything in between including cancer and problems with the sack the heart is held in – termed the pericardium.
Heart disease can progress to heart failure in which there is an ineffective or inadequate flow of blood to certain organs and tissues. Usually one of two events can occur. In one case the heart cannot pump blood effectively to the body meaning there is not enough oxygen getting to the body’s tissues – including the brain and abdominal organs, as well as causing a backlog of blood in the lungs (this is known as left-sided heart failure). In the other case, the heart cannot effectively pump the blood coming from the body back to the lungs for re-oxygenation, which also causes a backlog of blood in the body’s tissues (this is known as right sided heart failure). Heart disease will slowly progress to either left or right sided heart failure, or sometimes in severe conditions, to both.
Signs & Symptoms
Signs of heart disease can be subtle to begin with however, the symptoms usually worsen with time. Many times owners will miss these first few signs completely to begin with. Any or all of the following can be a sign of heart disease ( in no particular order):
· Weight loss
· Exercise intolerance
· Pot Belly
· Difficulty breathing
When heart disease deteriorates in to heart failure we usually see the following:
Right sided heart failure:
· Pot belly (due to fluid accumulation in the abdomen),
· Weakness, lethargy & weight loss (due to decreased oxygen content via blood from the lungs)
· Difficulty breathing (due sometimes to the formation of fluid between the lungs and the chest wall)
Left sided heart failure
· Coughing & difficulty breathing(due to fluid accumulation in the lungs)
· Weakness, lethargy & weight loss (due to decreased amount of blood circulating to the body)
· Fainting (due to inadequate well-oxygenated blood getting to the brain).
Whether you have noticed some of the above signs and symptoms or not, whatever the case, a full Veterinary check up can usually help confirm or deny any suspicion as well as pick up any early clues if you haven’t noticed any signs. At every annual health check, your Veterinarian will be sure to have a good listen to your dog’s chest. In many cases of heart disease, a heart murmur, arrhythmia or pulse problem will be picked, however this is not always the case, and oftentimes further diagnostic testing needs to be done to confirm or deny a heart problem. Even if your Veterinarian notes an abnormality after listening to the heart, he or she will then usually recommend further workup to diagnose the exact cause of the problem.
As mentioned earlier there are many shapes and forms of heart disease ranging from congenital problems, to valve problems, to rhythm and rate problems, to heartworm and problems with the size of the heart muscle (to name but a few). These further diagnostic steps help confirm the exact cause of the problem in order to start an appropriate treatment. Further diagnostics can include any or all of the following (in no particular order):
· Chest xrays – to look for abnormalities with the heart size and shape and to look for congestion of the lungs
· Electrocardiogram (EKG) – for checking heart rhythm and rate and to follow up on any arrhythmias heard in the consultation room
· Echocardiogram – an ultrasound of the heart to find valve of muscular problems in order for your Vet to define the cause of the heart disease
· Blood pressure monitoring
· Referral to a cardiac specialist – in many cases, your Vet will choose to refer you on to someone who deals only with canine and feline cardiothoracic medicine and surgery. This will be particularly true with young puppies who have a congenital heart disease.
After carrying out several (or all) of these diagnostics, your Veterinarian will have a fair idea as to the cause of the problem in your dog, in order for a prognosis to be given and a treatment plan to be made.
The treatment your Veterinarian prescribes really will depend on the cause of heart disease that has been diagnosed. It can include any or several of the following (in no particular order):
· Diuretics – drugs that help remove a backlog of fluid from the body. These are particularly important to help get fluid off the chest (if your dog is coughing) or fluid from in the abdomen (if your dog has developed abdominal fluid - known as ascites). The drug usually given by Vets is called Furosemide, however there are several other diuretics that are better for certain conditions, including Spirinolactone among others. Your Veterinarian will prescribe the most appropriate one for your dog’s condition.
· Positive Inotropes – these drugs help the heart beat with more force in order to maintain blood pressure and oxygen supply for the body. A new drug called Pimobendan (tradename Vetmedin) is now available for dogs and is perfect for many causes of heart failure.
· ACE inhibitors – these are drugs that help lower blood pressure in certain cases as well as lowering salt retention. Drugs such as Enalapril (Fortekor) and Benazepril are such examples and these can be used instead of a positive inotrope or alongside it.
· Diet change – changes in a dog’s diet are usually necessary since heart disease, as well as the drugs involved, alter electrolyte balances. It is important the amount of sodium ingested in the dog’s diet is kept to a minimum to help prevent fluid accumulation.
· Intensive care – in cases where heart disease develops to heart failure, there are times when these dogs need supplementary oxygen, IV fluids and IV medications until they are more comfortable breathing and seem more relaxed to be able to go home.
· Surgery – this is usually only reserved for young puppies with congenital problems and requires referral to a specialist Veterinarian cardiothoracic surgeon.
Prognosis and ongoing care
The prognosis and long-term outcome of a dog’s heart disease really does depend on the root of the cause of each dog’s individual problem. After the routine diagnostics have been carried out by your Veterinarian they will take the dog’s condition and age into consideration and give you an idea of long term prognosis with effective treatment. It is also important to remember that once diagnosed with heart disease, your dog will need ongoing checkups, prescriptions and dosage changes throughout his or her lifetime.
It is of utmost importance to continue to medicate your dog strictly as directed by your Veterinarian, as well as to stick to your dog’s change in diet – no treats or tidbits, just the food prescribed. Always be sure to have plenty of water available for your dog, particularly if he or she is on diuretic medication.
There may be times when your dog is very short of breathing, coughing on an ongoing basis, is weak or has fainting episodes. All of these instances really do warrant a full Veterinary examination and in many cases intensive care for a few hours or overnight until stabalized.
If you have questions about a certain breed or a certain heart condition be sure to ask me and my colleagues online any time 24 hours a day, seven days a week using this feature:Sadly, if your dog develops heart disease, he or she was always going to and there really isn’t anything at this stage that can be done in Veterinary medicine to prevent heart disease from occurring. Do beware however, that certain breeds are definitely more prone to developing certain heart problems than others and be sure to investigate any breed thoroughly before you purchase it.
It is most important to remember that any heart condition is best treated early on – so always keep an eye out for the signs and symptoms mentioned and don’t skip your pet’s annual health checks. For more information on heart disease and signs to watch out for, purchase the Ultimate Guide to Canine Health.