And now….a story from our Vet, Shannon Riggs, DVM
Great horned owl #13-757 arrived at Pacific Wildlife Care on May 28 after being found entangled in a barbed wire fence. The bird’s rescuer was able to cut the small section of fence around which the bird’s right wing was wrapped and bring the bird to the clinic.
GHOW 757 sustained a significant injury to the underside of the patagium (or “wing web”) of the right wing. A single barb had become embedded in the skin and, while struggling to free himself, the owl wrapped the skin tightly around the barb, tearing the skin. The result was a large open wound approximately three inches in diameter. Luckily, there was not significant damage to muscle or tendons and the bird was in good condition otherwise so, despite this severe injury, we decided to try working with this bird.
Barbed wire entanglement is relatively common injury for birds of prey, especially great horned owls. The birds apparently don’t see the wire, or that there are barbs on the wire, and become caught, usually by a wing, as they are trying to fly through. In struggling to free themselves, the birds often become more tightly trapped, wrapping themselves repeatedly around the wire. The tightening acts like a tourniquet, compromising blood supply to the entangled wing. Often, so much damage is done, both from the initial injury and from later loss of tissue due to the constriction, that these cases are not salvageable.
Because the skin that had been covering the wound site was so damaged on this owl, it was no longer viable and could not be used to repair the defect. Because the skin of the patagium is stretched taut in flight, there is very little extra skin around the injured area that can be moved over such a large defect. We were therefore left with having to manage the injury as an open wound. Potential complications that are of concern are the potential for infection and loss of viability of exposed muscle, tendons, blood vessels, and nerves.
The owl was started on medications to prevent infection and to manage pain. Luckily, the owl ate well on his own from the beginning, so his handling could be decreased by placing his medications into food items. Daily dressing changes were performed, applying wound care products that keep tissue hydrated and promote healing. Two weeks after admission, when the wound was looking clean and healthy, we decided to try a type of tissue graft. Specially treated porcine tissue, a commercially available product used as a tissue patch, was affixed over the wound under anesthesia. We continued to manage the wound 2-3 times per week, cleaning the tissue graft site and applying gel to keep the graft hydrated. Unfortunately, after approximately 2 weeks, the graft was no longer viable and had to be removed. We then found another product, a biological glass substance, which stimulates growth of new blood vessels and therefore healing.
The owl has shown a good response to this treatment. Over the past month, the wound has been checked, cleaned, and a new dressing applied twice weekly. The wound has contracted significantly without the formation of scar tissue, which would have impaired the ability of the wing to extend fully. At this point, it seems that the owl is making significant strides toward release. While it is always impossible to make predictions about wildlife cases, as any number of things can happen that could change the course of a patient’s rehabilitation, if things continue as they have been, the prospects for this owl’s release are good. It will likely still be several weeks before we will know for certain, but we are hopeful that this owl will be able to return to his wild life.