An arteriovenous Fistula is a condition where the connection between an artery and a vein is abnormally fragile. When a fistula is large not enough oxygen gets to tissue and in some cases, no oxygen at all is received. Because of the defect a dog’s heart tries to compensate by pumping blood at a much faster rate and this can lead to dog's experiencing congestive heart failure. An arteriovenous fistula is a serious condition and one that needs diagnosing and treating as soon as possible.
Where a fistula develops varies and they can form in various places around the body which includes the following:
The condition can affect any dog, but some breeds are more predisposed to developing arteriovenous fistulae than others, with the English Bulldogbeing high on the list.
Because an arteriovenous fistula can appear anywhere on a dog's body, symptoms tend to be quite different depending on their location. However, a lesion will form on the site of a fistula and these lesions are warm to the touch, but they do not cause a dog any discomfort or pain. With this said, if the lesion forms on a dog's leg, the signs of there being something wrong may well include the following:
When the fistula affects a dog's heart it could lead to them suffering congestive heart failure, the symptoms of there being something wrong could include the following:
When an arteriovenous fistula negatively impacts a dog’s internal organ, the symptoms could include the following:
It is very rare for a dog to be born with the condition because they generally form due to traumatic damage to blood vessels or because a tumour has developed at a certain site on a dog’s body. It could be due to a complication that occurred during or after surgery. A fistula can form if a dog has been given an injection close or around a blood vessel.
A vet would need to have a dog's full medical history and be told how the onset of their symptoms occurred and they would then typically recommend doing the following tests:
Because an arteriovenous fistula can seriously impact blood flow, a vet might recommend taking thoracic X-rays which would establish if a dog's heart is larger than it should be. This could also permit them to see if there are any signs of a dog’s heart having to work overtime to compensate for the defect. A vet may also recommend doing a Doppler ultrasound which could show up abnormalities in blood flow in a lesion. When it comes to locating where an arteriovenous fistula has formed, a vet might recommend doing an echcardiogram and if they want to determine its outline, they may well suggest doing a selective angiograph.
When a dog is diagnosed with the condition, the problem would need to be corrected which means undergoing surgery. The downside is that there is always a risk of a fistula recurring and in some instances a vet might recommend removing an affected appendage altogether to prevent this from happening. There is another less invasive procedure called “transcatheter embolisation” of blood vessels which allows vets to reach more remote lesions through a dog's blood vessels.
When a dog is diagnosed and subsequently treated for an arteriovenous fistula, a vet would need to see them on a regular basis to evaluate their condition, more especially if they had to undergo any sort of surgery to correct the problem. Regular visits allows the vet to see if the problem has recurred in which case things can be caught and put right earlier rather than later.