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Propatagial tendon injuries are common in wild birds following entanglement or barbed wire injuries. The propatagial tendon runs along the leading edge of a bird’s propatagium, or wing web, and birds with a torn propatagial tendon have reduced lift and glide efficiency, loss of normal wing camber, and in owls it can impact their ability to fly silently and thus hunt effectively.
For a wild bird this means unless an injury to the propatagial tendon is repaired, the bird is unlikely to be considered releasable. These injuries are difficult to manage, particularly in small species where surgical approaches are impractical due to tendon size and limitations posed by the anatomy of the propatagium.
Conservative management of these injuries can be attempted and result in formation of a fibrous bridge that strengthens over time, similar to human Achilles tendon injuries.
Case description
A wild Australian boobook owl (Ninox boobook) presented following entanglement in barbed wire. The bird was an adult in good body condition (280g). It received a full veterinary examination under general anaesthesia including physical examination, ocular examination, radiographs, blood diagnostics of PCV, TP and estimated white cell count, and faecal examination.
During physical examination it was noted that the bird had an injury to the leading edge of the left propatagium with acute rupture of the propatagial tendon. Fresh tendon ends were visible. Soft tissue contusions to the propatagium were minimal and the remaining exam was without significant findings.
The bird was intubated using a size 2 uncuffed endotracheal tube and maintained on isoflurane. An intraosseous catheter was placed into the left tibiotarsus and Compound Sodium Lactate (Hartmann’s) provided at 10ml/kg/hr throughout the procedure. Feathers were removed on the affected propatagium to reveal the injury to the propatagial tendon, taking care not to cause further tearing. A dry crust over the exposed ends of the propatagial tendon was removed using Dumont forceps and flushed with sterile saline (Sodium Chloride 0.9%).
Following aseptic preparation, the propatagial skin was closed using 5-0 polydioxanone (PDS II, Ethicon) with single interrupted sutures placed 2mm apart. Sutures were placed at the leading edge, ventrally, and dorsally, ensuring the propatagial tendon was covered. A circular defect in the propatagium remaining caudal to the tendon was left to heal by secondary intention. A hydrocolloid dressing (Comfeel One) was cut to size and placed over the surgical site.
A padded cardboard spacer was placed on the ventral surface of the wing to maintain the propatagial tendon in relaxed extension during placement of a figure 8 bandage to encourage better alignment of the tendon ends and avoid contracture of the propatagium. Prior to recovery from the anaesthetic, the bird was administered Meloxicam 0.5mg/kg (Ilium Meloxicam) intramuscularly and Amoxicillin-Clavulanic Acid 150mg/kg (Noroclav) subcutaneously. The bird recovered uneventfully.
To restrict movement, the bird was housed inside an intensive care hospital box (0.7m x 0.6m x 0.5m) at ambient temperature with a 12-hour day/night cycle. It was provided an artificial turf covered block perch. The bird was calm throughout the hospitalisation process. The patient received Meloxicam 0.5mg/kg (Metacam Oral Suspension) orally twice daily for 7 days and Amoxicillin-Clavulanic Acid 50mg tablets (Noroclav) orally twice daily for 10 days following the procedure. The bandage was changed under general anaesthesia at 7 days following the procedure and then every 5 days.
Four weeks following the procedure there was a strong union of the propatagial tendon. However, it was poorly covered by skin. A conservative attempt was made at covering the area with a hydrocolloid dressing, but a week later the skin had further receded. A repeat general anaesthetic was performed and the dry tissue over the propatagial tendon removed using Dumont forceps, exposing the union.
The fibrous ring of the receding propatagial skin proximally and distally was opened using fine iris scissors and the skin aligned in a similar fashion to the initial procedure. A hydrocolloid dressing was placed over the surgery site. No figure 8 bandage was placed following the second surgery.
Three weeks following this second procedure the skin had healed over the propatagial tendon and feathers began emerging. A follow-up radiograph confirmed alignment of the propatagial tendon. The bird was moved into a facility allowing exercise. Four weeks following exercise, the feathers had almost fully covered the affected propatagium and the bird showed symmetric, even wing beat. Flight was silent. The bird was subsequently released back into the wild.
This case demonstrates a successful outcome in avian propatagial tendon repair using a technique to approximate fresh ruptured tendon ends combined with immobilisation and frequent controlled physiotherapy under general anaesthetic. Likely factors that contributed to the success in this case include the fresh nature of the tendon rupture and the lack of significant propatagial soft tissue contusions commonly encountered in barbed wire entanglement injuries.
It is likely conservative propatagial tendon repair attempts are currently underused in avian medicine, and this case suggests this approach can be successful.
Dr Jana Schader
BA DVM MANZCVS (Avian Medicine & Surgery)
Avifauna vet
Dr Jana Schader is a veterinarian based in New South Wales with experience working in companion animal, avian, exotics and zoological practice, as well as the wildlife sector. Her main passion is working with avian patients whether as pets, aviculture or wildlife.
Dr Schader is an active raptor rehabilitator with significant experience in rehabilitating complex injuries and has published the Practical Handbook of Australian Raptor Rehabilitation. She is currently completing a PhD with the University of Queensland and investigating naturally occurring neurotoxins as the cause of lorikeet paralysis syndrome.
In her free time, Dr Schader enjoys being outdoors, birding with friends and searching for terrestrial orchids.
