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Bubbles under skin are damaged air sacs

In the last few months my 16-year-old severe macaw, Skooby, has developed what appear to be bubbles of air under the skin on his neck and back. The vet used a syringe to deflate one of the bubbles and there was no fluid in it, only air. He gave me some antibiotics, which I used for several days. The bubble never fully disappeared. Now several months later they are still here and a large tightly stretched area has developed on the front of the neck and a smaller one on the back. What could be the cause of this?

--David Ewing, Pinson, Ala.

THE AIR BUBBLES you see are a sign that an air sac somewhere in your bird's body has been damaged. The bubbles are either pockets of air - called subcutaneous emphysema - that has escaped from a leaking air sac, or they are air sacs located just beneath the skin that are distended due to an inflammation called air saculitis. An explanation of bird anatomy might help you picture what's going on. Instead of a diaphragm to separate the chest (thorax) from the abdominal cavity, birds have one body cavity filled with extensions of the lungs called air sacs. These thin-walled structures also sit just under the skin along the back of the neck and top of the head and even extend into some of the bones. Air sacs help birds fly and help keep waterfowl afloat. (In pelicans, air sacs under the skin on the front of their bodies allow them to dive from 30 feet without injuring themselves and then pop back up to the surface.) If the wall of an air sac tears, air will migrate up and form a pocket under the skin. When air sacs that sit just beneath the skin become infected or damaged and their connection to the rest of the respiratory system is blocked, they also can distend and form what look like bubbles. In my experience, these pockets of air, although unsightly, are rarely infected or life threatening. They're usually the result of a leaking sac somewhere in the bird's body that eventually heals, especially if your veterinarian can speed the process along with antibiotics. (Leaking air sacs cannot be surgically repaired.) However, bubbles can interfere with movement and make your bird uncomfortable. Drawing off air with a needle is a very temporary fix; the leaking air will only rapidly reform the pocket. An excellent way to take care of large bubbles is a Teflon stent, a small valvelike unit that is surgically implanted. The stent protrudes through the skin, allowing trapped air to escape. Depending on the location of the air bubble, the stent might be placed high up on the back of the neck where the bird can't reach it. Or it might have to go on the cheek, under the wing or along the back; however, in my experience, most birds leave stents alone. Stents can be left in place for long periods of time, even permanently. If the damaged air sac heals and the stent is no longer needed, it can be removed.

Dr. James Harris James Harris, DVM is owner and medical director of the Mayfair Veterinary Clinic in Sandy Bay, Tasmania, Australia. He founded Montclair Veterinary Hospital in Oakland, Calif., and has served as medical director and chairman of the board for the International Bird Rescue Research Center in Berkeley. Dr. Harris' numerous professional honors include California and National Bustad Companion Animal DVM Awards. Copyright 2010. All rights reserved.

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