Your dog can cough for any number of reasons, and the occasional cough isn’t anything to be all that concerned about. However, if your dog is coughing persistently, he could be ill.
Kennel cough is one of the most common causes of a honking, hacking cough, and it’s easily passed from one dog to another. In fact, a while back, we had a bit of a kennel cough epidemic going on down at the dog park. Janice and Leroy are inoculated against it, though, so we ended up unscathed.
Other causes of coughing could include fungal infections, distemper, bronchitis, an infected airway, heartworm or (rarely) lung cancer. If your dog has been coughing for more than a week and seems tired or loses his appetite, a trip to the vet would be in order. The vet will ask you a number of questions, and may also run tests in order to determine the cause of the problem.
In addition to the conditions already mentioned, with heart problems in dogs, coughing can be an indication that something is not right. There will be other symptoms, as well, and we’ll talk about them later. Sadly, heart problems will usually lead to congestive heart failure. Before we get into that, though, let’s take a look at how your dog’s heart works.
The Canine Heart
The heart in all mammals works in essentially the same way. It’s basically a pumping system that moves blood through the body. Although it’s common to refer to the heart in the singular, as “a pump,” it’s really two, located side by side. You could think of the right side of the heart as a low-pressure pump. Its job is to take blood from the body and send it to the lungs, where the carbon dioxide is filtered out and the blood is re-oxygenated. On the left side is a more robust, high-pressure pump that has the job of sending the re-oxygenated blood back through the body. If this cycle stops, the body dies.
Within each pump, there are two chambers. The first is the atrium, which sends blood through a valve to the second chamber, the ventricle. The valve also prevents the blood from flowing back when the ventricle contracts to deliver blood. There are also other valves in the blood vessels that take the blood from the ventricle, and work to prevent backflow.
How well the heart works depends on a number of factors, including physical condition, whether the mammal is exercising vigorously, and even on the mammal’s mental state. It can also, of course, be affected by disease.
Congestive Heart Failure
When congestive heart failure occurs, it’s because the heart can no longer pump blood the way it should. The blood output decreases while the blood entering the heart increases. This also causes excessive fluid pressures in the blood vessels and the tissues surrounding them. In dogs, congestive heart failure is most commonly caused by DVD (degenerative valvular disease) or DCM (dilated cardiomyopathy).
DVD occurs when the heart valves are not able to prevent blood from flowing back through the ventricle. It frequently occurs in the valve that is located between the left atrium and the left ventricle: the mitral valve. When it originates in the mitral valve, the condition is referred to as MVD (mitral valve disease). It’s more common in small, elderly dogs than in large ones. While your veterinarian can make a diagnosis of DVD or MVD, he or she might not be able to tell you exactly what caused the condition.
DCM is an enlargement of the ventricle. It’s a progressive condition, and as the ventricle enlarges, it no longer contracts as strongly as it should. You might not notice any symptoms if your dog has DCM, at least not in the early stages. As it progresses, though, this is one of the heart problems in dogs that coughing could tip you off to. DCM is more common in large dogs. As with DVD and MVD, the cause might not be identifiable.
In the early stages of the disease, your dog’s body will attempt to compensate for the decreased blood flow from the heart by constricting the blood vessels. This will lead to an elevated heart rate, as well as water and sodium retention. Taken together, these three things cause the dog’s blood pressure to rise, so the blood circulates more or less normally. However, this same compensatory measure eventually leads to fluid accumulation or congestion. If it occurs on the right side of the heart, there will be abdominal congestion. If it occurs on the left, the result will be pulmonary edema – an accumulation of fluid in the lungs.
Symptoms of Congestive Heart Failure
The symptoms of heart problems in dogs are several; coughing is just one. Other common symptoms that might indicate congestive heart failure are:
- Loss of appetite
- Inability to exercise for any length of time
- Trouble sleeping (particularly on one side or the other)
- Fluid buildup in the abdomen
Your veterinarian will make his or her diagnosis based on the foregoing symptoms and after listening to your dog’s heart. If MVD is present, it’s pretty much a given that there will be a heart murmur. Pulmonary edema sounds like “crackling.”
Other diagnostic tools could include electrocardiogram, echocardiogram, chest radiographs and bloodwork.
Treatment for Congestive Heart Failure
There is no real cure for congestive heart disease in dogs. This is because it is pretty much always due to a physical change, like a weakened ventricle or a badly working valve, and also because the condition is progressive. Your veterinarian can offer treatments that will ease the symptoms somewhat, though.
One course of action might be to prescribe a diuretic. This is medication that increases urine output, and thus reduces the fluid load. Furosemide is one common diuretic.
Vasodilators can be prescribed in order to open up the blood vessels. This eases the load on the heart.
Medications are also available that can work to strengthen the heartbeat.
If these heart problems in dogs are such that coughing is problematic, your veterinarian can also prescribe a cough suppressant, provided that the coughing is due to compressed airways caused by an enlarged heart. If the cause is pulmonary edema, a cough suppressant will do more harm than good.
Restricting the dog’s sodium intake might also be recommended, since the amount of water stored in the blood vessels and in the surrounding tissues increases in proportion to the amount of sodium in the body.
It’s also very important to closely monitor the amount of exercise your dog gets. He shouldn’t be allowed to over-exert himself, as doing so could make the condition worse. It might even result in death.
The Prognosis for Congestive Heart Failure
Unfortunately, there are no surgical methods for treating congestive heart failure in dogs, and as previously mentioned, the condition can only be managed; it cannot be cured. With DVD or MVD, the survival rate following discovery of the symptoms is better than one year. With DCM, the prognosis may not be quite so good.
Congenital Heart Disease
Congenital heart disease is different from congestive heart failure in that a dog is born with the disorder. Usually, it’s passed down genetically from one or both of the parents. Sometimes, a puppy can be born with more than one defect. Congenital heart disease presents as malformation in the chamber, valves, or great vessels. It can also be due to abnormal connections between the chambers of the dog’s heart. Because congenital heart disease is hereditary, dogs that are affected should not be bred.
Now, let’s take a look at three of the most common types of congenital heart disease.
PDA (patent ductus arteriosus) occurs when the ductus arteriosus, which is the blood vessel that connects the pulmonary artery and the aorta, does not close properly. When a puppy is in utero, this vessel stays open so that blood doesn’t get into the lungs. The lungs are non-functioning until the puppy is born, and as soon as the puppy begins to breathe, the ductus arteriosus is supposed to close so that the blood will flow normally. When it remains open, an overload of blood volume is created in the veins and the pulmonary arteries on the left of the heart. This overload causes the left chambers of the heart to dilate, and leads to fluid buildup in the lungs.
PDA can be corrected surgically, provided that it is identified. If it is not identified and corrected, though, the prognosis is grim; the puppy is not likely to live for much more than a year.
PS (pulmonic stenosis) is a condition that occurs when the pulmonic valve is abnormally formed in such a way that it is too narrow to allow blood to flow properly. With this condition, the heart’s right ventricle has to work very hard, and at high pressure to pump blood through the valve. Then, enlargement of the right ventricle occurs, and in some cases, fluid can build up in the abdomen and the liver can become enlarged.
Depending on how narrow the pulmonic valve actually is, it can be possible for a dog to live a full life provided that the condition is treated with medication. If the condition is severe and not treated, the prognosis is not good. Most dogs will die within the first few months.
PS affects small breeds more often than it does larger dogs.
SAS (subaortic stenosis) is another condition where narrowing is the problem. It occurs below the aortic valve, and is most often due to fibrous tissue or nodules that develop in the left ventricle outflow during the first month or two of the puppy’s life. This causes the blood flow through the left ventricle via the aorta to become obstructed. Again, as with PS, this means that the heart has to work a lot harder to pump blood. The difference, though, is that this is a condition of the left ventricle, not the right.
This condition is often identified initially as a heart murmur, and as it progresses, more serious arrhythmias can develop. Ultimately, heart failure can occur. Large breeds are the most likely to be affected by SAS. It’s worth noting, though, that if a dog is only mildly affected, chances are good for a full, normal life.
Diagnosing Congenital Heart Disease in Dogs
Often, puppies with congenital heart disease will show no symptoms. Most often, though, it’s discovered during one of the first routine visits to the veterinarian. On that first visit, of course, the puppy gets his shots, is wormed, checked over for any problems with the hips and joints, and has his heart listened to. If the vet hears a murmur, then he may suspect a congenital heart defect.
What exactly is a murmur? It’s turbulence in the blood flow that creates an abnormal vibration. You don’t need to panic just because your vet has identified a murmur, though; they’re actually quite common in puppies. In fact, my Janice had one. It resolved on its own, as most of them do by the time the puppy reaches the age of about four months.
The kind of murmur that causes concern is louder than an “innocent” murmur, and sounds quite different. With PDA, for instance, the blood flow sounds a lot like the churning noise your washing machine makes. SAS and PS create what’s called an “ejection” murmur, which is a sort of thump that occurs when blood is pumped from the heart to the lungs and body.
If your vet hears one of these troublesome murmurs, he or she may refer you to a veterinary cardiologist, who will do an echocardiogram. This is a type of ultrasound that uses Doppler combined with color flow to get a picture of the heart and its great vessels. Usually, this is all that is needed to identify congenital heart disease. However, if the condition appears to be complex, the cardiologist may also want to do an angiogram to determine the full extent of the damage. Other diagnostic tools include blood work, blood pressure readings and thoracic radiographs.
Complications of Congenital Heart Disease
With PDA, congestive heart failure can result during the first year of the dog’s life due to volume overload in the left heart and the lungs. Symptoms of these heart problems in dogs are coughing, weakness, exercise intolerance, lethargy, trouble breathing, and possibly collapse. The heart can also beat rapidly and irregularly. This is when the condition manifests as left-to-right shunting when the blood flows from the aorta to the pulmonary artery. Rarely, the flow can go in the opposite direction (right-to-left shunting). When this happens, cyanosis can also occur, because the dog simply never gets enough blood to his lungs. Dogs that are afflicted with right-to-left shunting will seldom live for more than a few years, and surgery is seldom an option.
Dogs that have severe PS will have much the same symptoms, and in rare instances, may experience right-sided heart failure as identified by an enlarged liver and a buildup of abdominal fluid. Sometimes, little or no medication is needed to manage the condition, and it is very rare for sudden death to occur in a dog that has PS.
The symptoms of severe SAS are also essentially the same, although there is a higher risk of sudden death due to a correspondingly high risk of developing ventricular arrhythmias. SAS also carries with it a particularly nasty complication: a high risk of developing infected heart valves. This can lead to sudden death. However, if the dog has only mild SAS, there is a good chance or a normal life provided the condition is treated.
Treatment for Congenital Heart Disease
There are two options for treating PDA: surgical ligation and transcatheter occlusion, both of which are simply ways of closing the open vessel. Transcatheter occlusion is less invasive and will result in a faster recovery. It involves placing an occlusion (closing) device into the PDA by means of a catheter, which is introduced into the femoral artery. This procedure does some risks, like bleeding from the artery or puncturing the PDA with the catheter (which could cause fatal bleeding) but is less risky than the surgical ligation (thoracotomy). With either approach, if the dog is in heart failure, he will need to be stabilized before either approach can be sued, and will also require consistent monitoring and stabilization for some time following treatment.
With severe PS, balloon valvuloplasty is the preferred treatment. This is a very effective procedure, with a success rate of about 80%. Sometimes, it’s not an option, though. If the coronary artery is abnormal, or the valve annulus is severely narrowed, treatment may not be possible. Assuming that it is a practical approach, though, the dog can live a full life. The procedure involves accessing the right heart by way of the right jugular vein. A catheter with a balloon on the end is inserted, and then the balloon is inflated. This causes the valve to open. There are few significant risks. Rarely, fatal arrhythmias can develop. Equally rarely, the right ventricle could collapse, again causing death. More often, though, the side effects of the procedure are limited to swelling or bruising at the point where the catheter is inserted into the dog’s neck.
SAS, sadly, is the congenital heart defect that is the least responsive to therapy. Most of the time, the veterinarian will have few options other than to try to manage the condition using beta blockers and anti-arrhythmic drugs. Usually, the dosage will also have to be increased as the dog ages and gains weight. If left-sided heart failure occurs, other medications can be employed to give the dog a better quality of life. The condition is not considered to be curable, though.
Prognosis for Congenital Heart Disease
Severe PDA, if not corrected, will usually result in the dog living for no more than a year. If the condition is mild or moderate, the dog may not even show symptoms, and can lead a normal life without treatment.
Dogs with PS will also usually enjoy a symptom-free life and no reduction in life span. If the condition is severe, though, and not treated by means of balloon valvuloplasty, heart failure will usually occur by age two or three.
SAS generally worsens up to the point where the dog achieves his full bodyweight, and then will not progress much beyond that point. A serious problem with SAS, though, as previously noted, is the possibility of aortic valve infections. Severe SAS will usually result in heart disease by the age of two or three, and the condition has to be managed if the dog is to survive beyond that point. The dog is unlikely to enjoy a full life span, though. And finally, mild SAS is easily managed and will not usually affect either the dog’s lifespan or his quality of life.
The Final Word
With heart problems in dogs, coughing is frequently the first symptom you’ll notice. A persistent cough, or one that sounds out of the ordinary, should never be ignored. If your dog seems to be hacking a bit more than usual, a trip to the vet would be a good idea; you might find out that there’s nothing to worry about, but it’s always best to err on the side of caution.
Keep in mind that coughing, and even heart murmurs, do not necessarily mean that your dog is seriously ill. It’s important to get a diagnosis, though, so that you know what your options are and what you need to do to ensure the best possible outcome for your dog.