The armadillo is a strange-looking mammal with a shell, that rolls up in a ball to protect itself. They are native to the Americas, and they share an odd trait in common with humans. They can contract and carry the ancient skin disease that affects humans, called leprosy. The strain of leprosy found in humans is Hansen's Disease, caused by Mycobacterium leprae. The disease attacks the skin and nerves of sufferers and has devastating effects on those afflicted with it, including skin disfiguration, loss of limbs, and eventually death. In ancient times, when no cure was available, and due to fear of the disease’s contagious nature, sufferers of leprosy were also kept isolated from the rest of the population, adding to their misery.
Modern drugs can successfully treat leprosy, and it is no longer common or feared in most of the modern world, although those in developing countries that cannot afford the medication still suffer from the disease. Recently, there has been a spike in cases in the United States, especially in Florida. It turns out that armadillos can carry M. leprae and can, and have, transmitted it to humans. While this is very rare, since leprosy is not highly contagious and requires close contact, and armadillos are not aggressive creatures, the development of these cases has caused alarm in the area where they occurred. So if humans can catch leprosy from armadillos, can dogs?
Can Dogs Get Leprosy from Armadillos?
Dogs do contract leprosy, but it is from their own species-specific form of leprosy, Mycobacterium simiae, not the same bacterium that causes leprosy in armadillos and humans. M. simiae is not transmissible to humans, and no known cases of the leprosy transmissible to humans carried by armadillos have been found in dogs to date. So if your dog shows signs of skin lesions, there's no need to send your dog to a leper colony just yet! The canine version of leprosy is treatable with medication, but can be serious if left untreated, causing many of the same skin disfigurements as the disease does in humans.
Does My Dog Have Leprosy?
The leprosy contracted and carried by dogs is not the same as the one that affects humans, and is not known to be transmissible to or acquired from people or armadillos. Canine leprosy, known as canine leproid granuloma syndrome (CLGS), is common in Australia, and is found most often in short-haired breeds, especially Boxers, Staffordshire Terriers, and Doberman Pinschers.
Subcutaneous skin nodules, often around the neck, head, and ears, 2 mm to 5 cm in diameter
Nodules are hard and painless
Sometimes there is hair loss on nodules
Large nodules may ulcerate
Secondary bacterial infections from scratching may occur
The disease in dogs is thought to be transmitted by biting insects, carrying the canine species-specific mycobacterium, M. Simiae, not armadillos!
Your veterinarian can make a diagnosis of canine leproid granuloma syndrome using biopsied skin samples examined under a microscope. Other conditions such as cysts, abscesses, tumors, and insect bites will also need to be ruled out.
You can learn more about canine leprosy at Canine Leproid Granuloma Syndrome in Dogs.
How Do I Treat My Dog’s Leprosy?
Usually, the disease resolves on its own, within one to three months. Monitoring by pet owners, to ensure secondary infections do not occur or that lesions do not increase in size to the point where they become ulcerated, is all that is required. If the disease does not resolve on its own, antimicrobial drugs can be administered and will generally resolve the condition successfully. If nodules become large and interfere, surgical excision can be conducted by your veterinarian to remove them. If secondary bacterial infections develop with the lesions, antibiotics will be prescribed for the infection. The prognosis for dogs affected by canine leproid granuloma syndrome is good and recovery is usually uneventful. If complications occur, medications and surgical options are available to successfully treat the condition.
How is Leprosy Similar in Dogs, Humans, and Other Animals?
Humans, dogs and cats, and apparently armadillos, can all get leprosy. Although the kind that dogs and cats get is different, some similarities exist.
Skin lesions occur
Antimicrobial drugs can be used to treat the conditions
They are not as contagious as once thought
How is Leprosy Different in Dogs, Humans, and Other Animals?
Leprosy tends to be species-specific and is not a vigorous bacteria, making testing for it difficult outside of its species-specific host. Differences in the leprosy that affects us versus the kind that affects your pets are:
The mycobacterium that affects humans is M. Leprae, while cats are affected by M. lepraemurium, and dogs are affected by M. simiae
In pets, the disease is much less serious, does not affect nerves and internal organs
In pets, the disease usually resolves on its own
Canine leprosy is thought to be transmitted by bug bites while human leprosy is transmitted through close contact with droplets of saliva and body fluids
Humans can contract leprosy from armadillos-- we probably gave it to them; but there are no known cases of pets contracting leprosy from armadillos
An Australian Boxer mix develops nodules under her skin around her head and neck. Her concerned owner takes her to the veterinarian to determine the cause. At the veterinarian’s, the pet owner reveals that her dog has spent a lot of time outside lately and the bugs have been bad this season. After examining the dog, the veterinarian takes a biopsy of one of the nodules and sends it for analysis. The sample comes back positive for M. simiae, the mycobacterium that causes canine leproid granuloma syndrome. The pet owner is instructed to watch her dog to see if the nodules disappear and discourage her dog from scratching or interfering with the nodules. Several weeks later, the nodules have disappeared and there is no need for further veterinary treatment.