As part of a study of porcupine mortality in Maine, New Hampshire, and Massachusetts, pathologists at the lab examined 44 dead porcupines during a 7-year period and found 12 had died from a disease caused by a fungus known to cause ringworm in wild and domestic animals.
“The fungus usually causes localized, often minor skin infections in animals and people,” said
|Porcupine with fungal disease (NH Veterinary Diagnostic Lab) |
veterinary pathologist David Needle. “In porcupines, however, the skin lesion becomes severe and spreads to the whole body, resulting in debilitation and death if not treated. The pattern of disease caused by this fungus has never been reported in porcupines.”
The porcupine’s response to the fungus is to try to slough it off by growing a large quantity of keratin, which Needle describes as “a self-adhesive sheet of dried-out cells.” But because the fungus thrives in keratin, and because no inflammation blocks the fungus, the fungus eventually grows over the animal’s entire body, including its eyes and ears in some cases.
Because the disease has only been diagnosed in the three states – plus a new case in Connecticut – Needle believes that a regional subpopulation of porcupines may be susceptible to the pathogen. Additional cases have been identified by wildlife-rehabilitation clinics in the region, and a newly developed treatment protocol is having modest success at healing the animals.
The fungus is zoonotic, which means it can be transmitted from animals to humans, although there are no reported cases of humans becoming infected by porcupines. But it is emerging at the same time that several other fungal diseases are affecting other wildlife populations around the world, from bats and frogs to snakes and salamanders.
How the disease found its way into porcupines is unknown, but Needle speculates that it probably emerged in the last decade and may be spreading. Because porcupines are not commonly rehabilitated and not studied extensively, it is unknown how common the disease is at this time.
“Porcupines are quite populous in some areas and are sometimes viewed as a pest, so concern for their population numbers isn’t a high priority,” Needle said. “There isn’t a groundswell of financial backing to investigate the disease further. But in areas where fishers had been extirpated and have been recently reintroduced, there has been a plummet in porcupine populations. Added pressure from this fungus is not helping them. They are still common enough in New England that we are not aware of a significant population decline, but studies to assess this may be lacking.”
To get a better idea of how widespread the disease is, Needle is now assimilating data from 400 dead porcupines studied at diagnostic labs across the country during the last 20 years. “We just started, but this new disease might be the most common diagnosis,” he said.
This article first appeared in the autumn 2020 issue of Northern Woodlands.