Baylisascariasis (Raccoon Disease) in Dogs

The raccoon is a primary host for the baylisascaris procyonis parasite though their health is not affected by being a carrier. The danger to dogs is very real, however. Exposure to the feces of raccoons infected with the roundworm sets the stage for infection. By ingesting the eggs found in the feces, or eating prey (like rabbits or birds) that have the infection, your dog can contract the raccoon roundworm. Consequences can be severe; for example, baylisascaris can lead to intestinal obstruction or blindness.

Raccoon disease refers to the raccoon roundworm, baylisascaris procyonis, a parasitic worm that lives in the intestines of this mammal. Infection from this intestinal nematode can cause severe neurological, visceral, and ocular complications in dogs, humans, other mammals, and birds.

Studies show that contracting the raccoon disease is rare. Despite this fact, care should be taken to not expose your family pet to the risk of ingesting baylisascaris procyonis eggs. Symptoms in dogs are listed below.

• Abnormal increase in muscle tension (hypertonia)
• Difficulty swallowing (dysphagia)
• Lethargy
• Circling
• Rolling
• Holding the head to one side, with muscle spasms (torticollis)
• Loss of balance (ataxia)
• A need to lie down (recumbency)
• Loss of coordination
• Tremors
• Fatigue
• Blindness
• Rigidity (opisthotonos)

Raccoon disease can cause intestinal obstruction, so be aware of symptoms pertaining to that, such as vomiting, abdominal pain, and loss of appetite.

Types

The eggs of the raccoon roundworm will develop in the environment (after being passed in the raccoon feces) for a period of two to four weeks before becoming infectious. They can remain so for months or even years. There are three types of raccoon disease caused by the parasite.

• Neural larva migrans
• The larvae travel to the brain and spinal cord, causing conditions like swelling of the brain (encephalitis)
• Ocular larva migrans
• Blindness can result when the larvae migrate to the eyes
• Visceral larva migrans
• Organ damage (such as enlargement of the liver), can occur as a consequence of migration to the organs

Because of the seriousness of the raccoon disease infection in dogs (and humans, since it is transmissible), the threat of contamination should be taken seriously.

• California and Georgia are very well documented States for the infection
• In the deep south and the southern Atlantic coast, the prevalence is lower but still there
• Canada has areas of infection
• The higher the prevalence, the more likely infection will be seen in canines
• Birds and rodents are also susceptible to the parasite
• In the raccoon, the worms develop into maturity in the intestine, followed by millions of eggs being passed in the feces
• The eggs finish their development in two to four weeks after being in the environment
• Canines and other mammals can ingest the eggs in contaminated soil, water or prey
• Puppies can suffer from more serious consequences than older dogs, though the danger of any type of raccoon disease whether it be neural, visceral or ocular, is possible in any age of dog
• Raccoons use “latrine” like areas to defecate, which can be in close proximity to human property and homes (decks, around the bottom of trees, park soil)
• Because dogs pass their feces indiscriminately, they can easily infect your yard with the eggs passed in their stool, and the parasite can remain viable for years
• Humans (children in particular as they may not wash hands properly after playing out of doors) can ingest the eggs by touching contaminated items, soil, raccoon feces, or dog feces

When you arrive at the clinic with your canine companion, be as informative as you can about your suspicions regarding the baylisascaris procyonis infection. If your pet frequents areas known to be populated with raccoons, let your veterinary team know.

If your dog may have eaten a bird or rodent that could possibly be infected with the parasite, be sure to mention this as well. If you have friends or family with canine family members that have been exposed in recent weeks or months to raccoons or their environment, tell your veterinarian. The more information you can provide, the better the diagnostic process will be.

The symptoms that your dog may exhibit will vary in severity depending upon the number of eggs that have been consumed, or in the case of prey, the extent of illness and contamination of the rodent, rabbit or bird. Your veterinarian will base her diagnosis partly on the symptoms and the information you can provide.

A stool sample will provide further clues to the diagnosis. With fecal flotation, eggs may be identifiable under the microscope, or perhaps visible worms will be seen in the feces or vomitus of your pet. If you feel that your pet may have raccoon disease, bring a fresh stool sample to the clinic with you. A fresh specimen will provide a conclusive means of analysis better than feces from your yard because the eggs will be more easily seen.

A biopsy is sometimes done, but the parasites can be difficult to identify in tissue.

The prognosis for dogs with a neural larvae migration is guarded. Corticosteroids will be administered to control the acute effects and the inflammation that accompanies a neural diagnosis.

In general, treatment is successful when canines are treated with broad-spectrum anthelmintics. The same type of drug that covers the dog roundworm infection will eliminate the raccoon roundworm. Heartworm medication that is normally given on a monthly basis as a preventative will kill the parasite though one treatment is not always enough to eradicate the infection. Studies show that three treatments of the anthelmintics on a two-week schedule has been shown to be effective. Be sure to bring your dog back to see the veterinarian for follow-up fecal examinations in order to be certain that the raccoon roundworm has been entirely removed from your pet’s body.

If your pet was fortunate to not suffer from a neural larvae migration, recovery could be relatively simple. It should be noted that the neural effects are most often seen in puppies. Roundworm Infection that travels to the eyes can result in blindness. If organ damage is severe, your pet will need therapy and follow up accordingly.

Ideally, prevention should be a part of the recovery protocol. Monthly heartworm protection is strongly recommended. Avoid allowing your furry family member to visit areas that raccoons may frequent. Prevent your dog from hunting wildlife. Destroy raccoon feces that might be in close proximity to your home with care, wearing gloves and washing your hands thoroughly. Also important is the careful removal of dog feces (they are likely contaminated), disposing of them in the garbage.

As for the raccoon population, prevent access to food in your yard. Keep sandboxes covered because these make a perfect latrine. Eliminate any water sources that may be attractive to raccoons and be sure to keep garbage inaccessible.