PHOTOS 1-5: Porcupines attack when threatened by facing away from the aggressor with erect quills. The quills detach on contact. Problems caused by porcupine attacks include pain, local tissue irritation and trauma, infection of tissues deep to the skin, quill migration into joints or vital organs and complications associated with penetration of thorax or abdomen. Dogs that have been attacked by porcupines usually have multiple quills embedded in the mouth and other areas of the head. The quills may also enter the eye and orbit. Porcupine quills may harbour bacteria that could evoke a septic or sterile foreign body reaction. The point of the quill is sharp and there are multiple barbs arranged around the point, promoting migration of the quill. The retrograde barbs on porcupine quills allow them to migrate up to 10 inches under the skin. Quills have been known to migrate to the eye and orbit, brain and vertebral column of dogs. Quill migration is associated with cutaneous draining tracts and sudden death. Infections with Staphylococcus spp. often occurs as these bacteria are present on the porcupine quills. These infections may lead to septic arthritis. The veterinarian may be unable to remove quills due to widespread distribution, depth of penetration, complete or partial removal prior to presentation, breakage, thick hair coat or obesity. To avoid injury and migration due to missed quills it is essential to do a complete physical examination with thorough oral examination. Dogs that have been attacked by porcupines need to be treated as soon as possible because the longer the quills remain in a dog, the more time they have to migrate deeper into tissues. Quills also become less rigid and more friable the longer they remain in tissue and this makes them more likely to break during removal.
REFERENCES: PHOTOS 1-5: 1. Johnson, MD, Magnusson, KD, Shmon, CL & Waldner, C 2006, ‘Porcupine quill injuries in dogs : a retrospective of 296 cases (1998–2002)’, Canadian Veterinary Journal, vol. 47, no. 7, pp. 677–682. 2. Grahn, BH, Szentimrey, D, Pharr, JW, Farrow, CS & Fowler, D 1995, ‘Ocular and orbital porcupine quills in the dog : a review and case series’, Canadian Veterinary Journal, vol. 36, no. 8, pp. 488-493. 3. Brisson, BA, Bersenas, A & Etue, SM 2004, ‘Ultrasonographic diagnosis of septic arthritis secondary to porcupine quill migration in a dog’, Journal of the American Veterinary Medical Association, vol. 224, no. 9, pp. 1467-1470.
Metadata assigned by Dr. M. van Schoor, Senior Lecturer, Dept. of Companion Animal Clinical Studies