Dog meets porcupine— and loses (again)

Although porcupines have 15,000 to 30,000 sharp quills that inflict pain, they are gentle creatures that want to be left alone. 

It's the veterinarian's (and dog's) worse nightmare — a Labrador retriever comes into the hospital at midnight with a face full of quills. He paws gently at his nose and shakes his head, but nothing helps. His muzzle is swollen and his eyes water with the pain, but he won't let his owner come near him because he knows that what comes next is even worse — the inevitable yanking of those darned spines from his sensitive skin. The Labrador has just met his match — Erethizon dorsatum, a.k.a. the North American porcupine.

Porcupines are members of the rodent family and are found throughout much of North America. They are nocturnal vegetarians, lumbering along the ground or climbing in trees in search of tasty leaves, twigs, bark, fruit, and nuts to eat. They are solitary by nature, except in the mating season, and prefer to live in wooded areas, although they are also found in deserts and grasslands. They nest in hollow logs, tree cavities, or earthen dens. Because porcupines move slowly and don't see well, their quills offer them an excellent measure of protection against predators.

Porcupines have 15,000 to 30,000 quills. These quills are modified hairs with hollow centers that are loosely secured within the skin. Like other hairs, these quills can be shed and regrown throughout life. Muscles attached to the quill base will pull the quills upright when the animal is frightened. The quills must be touched to be released; they cannot be "thrown" by the animal. When threatened, porcupines may use their tails to slap the attacker, releasing the quills into the assailant's muzzle, legs, and other regions of the body. The quills' needle-sharp tips easily penetrate animal skin, and microscopic barb-like projections on their tips prevent easy removal and encourage migration deeper into the tissues.

Although porcupine quills have some antimicrobial properties, they have been associated with infection, particularly if any pieces are left under the skin. Therefore, it is important to make sure the entire quill is removed; also, affected animals are often placed on antibiotics for about a week after quill removal since the quill can carry skin bacteria deep into the wounds.

Anesthesia or heavy sedation and pain relievers are usually administered when dogs have large numbers of quills since quill removal is painful. Additionally, thorough examination of the inside of the mouth should be performed to make sure there are no quills in the tongue or back of the throat.

To remove the quill, grasp it firmly with a pair of pliers near to its point of penetration into the skin. Pull quickly and firmly to free the quill, and then examine the end to make sure it comes to a sharp point and is not broken off. Some dogs will tolerate the removal of several quills without anesthesia, but most get wise to the process and will begin to avoid the person with the pliers.

Occasionally quills that have inadvertently been left in the dog will migrate to other sites. In one Rottweiler, 60-70 quills had been removed from the dog's head and neck area after a porcupine encounter. Several other quills migrated out of the chest skin thereafter. When a quill was found protruding out of the chest wall, the dog was presented to a board certified veterinary surgeon. Using a special scope to examine the inside of the dog's chest, the surgeon removed 45 quills from the heart, lungs, and surrounding tissue. Five days later, the dog required a second scoping procedure to remove an additional nine quills from the lungs and chest cavity. Fortunately the dog is doing well two years after the procedure.

Quills have also caused eye and joint infections from penetration into and around those areas. They have been found migrating along the spine and into the brain. In dogs with chronic draining wounds that do not clear up after antibiotic treatment, veterinarians may use ultrasound or special x-ray studies to find the quills. Occasionally surgical exploration is required to search for quill remnants and remove them.

One would think that a dog would learn its lesson after the first painful encounter. Unfortunately some dogs are slow learners, or they let their natural curiosity get the best of them. Don't be surprised if your Labrador goes back for a second look at this gentle but prickly creature.