Arteriovenous Fistula in Dogs: Is This as Scary as It Sounds?

So, your vet has told you that your dog has an arteriovenous fistula and that they may have been born with this rare condition. Just the name of this condition can be scary enough, but is it really that scary or is this just a big name for a small problem? The answer to this is that it depends on how advanced your pet's condition has become.

In simple terms, an arteriovenous fistula is a condition in which a fistula (an opening or passage) causes abnormal blood flow between a vein and an artery that often occurs after a traumatic injury. In the event the fistula is allowed to continue growing unabated, it can cause the flow of blood coming from the heart to bypass the capillary bed in the affected area.

When this happens, the lack of blood will make your pup's heart have to work that much harder as it tries to push more blood into the area to keep it properly oxygenated.  Although this might help in the short term, if the problem persists, your dog could suffer from what is known as "high-output" congestive heart failure as a result of the heart working harder than it is designed to for a long period of time.

Where Can an Arteriovenous Fistula Occur?

Unlike certain conditions that tend to occur in a very specific area of the body, an arteriovenous fistula can occur in many areas of your dog’s body, ranging from the limbs to the brain or any one of several vital organs. While it is quite possible for your dog to have been born with this condition, it is far more likely that they were subjected to some form of injury to the blood vessels in the area where your vet found the fistula.

The cause of the injury could be anything from falling from a high spot to being hit by a ball during play (dogs are very susceptible to this type of injury).  It is also possible that the fistula was caused by a secondary problem such as a tumor, surgery, or blood draw. This means that it is quite possible the same vet you take your dog to might have accidentally caused the problem. The most important thing to remember is that no matter what the cause of the fistula, you need to take your dog to the vet for treatment because it will only continue to worsen.

Diagnosis and Treatment of Arteriovenous Fistula

The best way for your vet to diagnose an arteriovenous fistula is to give your pup a complete and thorough examination, including an ultrasound and an echocardiogram (ECG). This will help him to determine the exact location of the fistula as well as its size. Once this is done, your vet can decide the best way to correct the problem.

Your vet has a couple of options when it comes to treating your pup's arteriovenous fistula. The first is surgery, during which he may be able to repair the fistula. While surgery is often quite effective, it does come with its own set of risks, including excessive blood loss, recurrence of the condition, and the loss of the affected limb.

In recent years, a new form of treatment has become available that involves inserting a catheter into the fistula itself. Known as a transcatheter embolization, the catheter blocks the flow of blood into the fistula and in doing so, reroutes it back to where it should be. The good news is that this procedure is less invasive and has a much higher rate of success.

When All Is Said and Done

After your pet has been successfully treated for the arteriovenous fistula, they will need to be seen by your vet for a number of follow-up examinations to make sure the fistula does not come back. Although there are limited things you can do to prevent the formation of an arteriovenous fistula, the best thing you can do is take steps to make sure your pet is not subjected to any type of traumatic injury. If you have any questions or think your dog might have an arteriovenous fistula, be sure to contact your vet immediately.