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Arteriovenous Fistula in Dogs , Symptoms , Diagnosis and Treatment

Arteriovenous Fistula in Dogs , Symptoms , Diagnosis and Treatment - Dogs Health care Articles

Arteriovenous Fistula in Dogs , Symptoms , Diagnosis and Treatment : Dogs Health care Articles; Arteriovenous Fistulae are acquired vascular malformations that allow blood flow to bypass the capillary bed, and as such allow arterial blood to directly enter the venous system. " src="http://gallery2.vetarena.net/image-1013.m.jpg" /> If large enough types may cause a significant fraction of the total cardiac output to bypass the capillary bed, making ... Arteriovenous Fistula in Dogs , Symptoms , Diagnosis and Treatment


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Arteriovenous Fistula in Dogs , Symptoms , Diagnosis and Treatment

Arteriovenous Fistula in Dogs , Symptoms , Diagnosis and Treatment

Arteriovenous Fistulae are acquired vascular malformations that allow blood flow to bypass the capillary bed, and as such allow arterial blood to directly enter the venous system. Arteriovenous Fistula in Dogs , Symptoms , Diagnosis and Treatment
If large enough types may cause a significant fraction of the total cardiac output to bypass the capillary bed, making it so that the tissues receive little or no oxygen.
Chronically, decreased vascular resistance can lead to fluid retention and high-output heart failure. The heart, in turn, tries to compensate for the lack of oxygen by pumping blood out to the body at a faster rate, which may lead “high output” congestive heart failure.
AV fistulae must be discriminated from extracardiac arteriovenous shunts due to single or multiple congenital defects of the vasculature.

The location of arteriovenous fistulae varies; reported sites include the head, neck, ear, tongue, limbs, flank, spinal cord, cerebrum (part of the brain), lung, liver, vena cava (major vein leading back to the heart), and gastrointestinal tract.

Types and Symptoms of Arteriovenous Fistulae in Dogs

The symptoms associated with an arteriovenous fistula will ultimately depend on the size and location of the fistula.
Typically, there is a warm, non-painful lesion at the site of the fistula. If the lesion is on a limb, the dog may display:
  • Swelling where you can touch the limb and a fingertip impression is left in the skin (pitting edema)
  • Lameness
  • Ulceration
  • Scabbing
  • Gangrene (Tissue dies and turns green)

Signs of congestive heart failure, which is often associated with this type of fistula, include:
  • Coughing
  • Difficulty breathing (dyspnea)
  • Increased heart rate (tachypnea)
  • Exercise intolerance

If the arteriovenous fistula causes organ failure, your dog may display:
  • Distention of the abdomen (liver)
  • Seizures (brain)
  • Weakness or paralysis (spinal cord)

Diagnosis of Arteriovenous Fistulae in Dogs

You will need to give a thorough history of your dog’s health, including the onset and nature of the symptoms, to the veterinarian. He or she will then perform a complete physical examination as well as a biochemistry profile, urinalysis, complete blood count, and electrolyte panel to help identify complications associated with an arteriovenous fistula. Biochemical abnormalities, for example, may suggest liver, kidney or other organ dysfunction.

Because arteriovenous fistulae significantly affect the dog's blood flow, thoracic X-rays may show enlargement of the heart and signs of over-circulation to the lungs. In addition, a Doppler ultrasound may show high-velocity, turbulent flow within the lesion.

To locate the arteriovenous fistula, your veterinarian may employ an echocardiogram on the dog. And to outline the lesion, which may be necessary for definitive diagnosis and is highly desirable for presurgical evaluation, the veterinarian may use selective angiography.

Causes of Arteriovenous Fistulae in Dogs

Dogs are rarely born with arteriovenous fistulas. Typically, they acquire the fistula due to traumatic damage to blood vessels, surgery complications, tumor(s), or problems arising from drawing blood or injections around the blood vessels (e.g., barbiturates)

Treatment of Arteriovenous Fistulae in Dogs

Dogs with clinical signs must undergo surgery to divide and remove abnormal connections between blood vessels. However, surgery can be difficult and labor-intensive and may require blood transfusions. While often successful, the arteriovenous fistula may recur even after surgery. Some dogs may even require amputation of the affected appendage.

A newer treatment option called transcatheter embolization involves using a catheter to block blood vessels. This method is particularly advantageous because it is relatively noninvasive and provides access to remote lesions via the blood vessels.

Homecare and Management of Arteriovenous Fistulae in Dogs

Your veterinarian will want to schedule regular follow-up appointments to evaluate your dog, especially if it underwent surgery. This will also enable him or her to determine whether the arteriovenous fistula has recurred.


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Source :
- Some content are taken from PedMD.com
- Image from asnjournals.org

Arteriovenous Fistula in Dogs , Symptoms , Diagnosis and Treatment

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