Silly moose behaviour usually an indication of fatal illness
Community Editorial Board
DON CAMERON
The Truro Daily News
Lately there have been a variety of feature stories circulating about moose being spotted near humans and highways. There have also sadly been moose hit on our highways recently as well as reports of illegal shooting of moose.
Moose have been on the Nova Scotia endangered species list for several years with an estimated mainland population of only 1,000 animals.
We usually think of moose as being a large majestic animal that lives far away from people, deep in the wilderness. Sometimes, moose live and move surprisingly close to people. Their natural instincts are to avoid us two-legged creatures whenever possible. However, sometimes, due to an illness, moose may approach people, communities and roads and make a nuisance or hazard of themselves.
One possible reason for the sudden appearance of moose in many populated locations at this time of year is that it is rutting season and the bulls are on the prowl, looking for their “Mrs. Moose” mate. However, if the moose is acting strangely, it is usually an indication of “moose sickness.” This is a relatively common disease that is often debilitating and fatal. The disease was identified more than 100 years ago.
Signs of moose sickness include: loss of fear of man, emaciated, aimless walking in circles and refusal to leave an area, holding head and ears in abnormal positions, frequent stumbling, poor co-ordination or balance and apparent weakness or paralysis of a leg.
Animals showing such severe signs of disease will eventually die.
Conservation officers and wildlife biologists are often called on to end the animal’s suffering. Sick moose can be a safety hazard along roadways.
People sometimes see a sick moose but do not report the sighting because they do not realize the animal is ill. Some sick moose have been photographed by people who have assumed the animal was especially tolerant of people.
‘People have reported leg or hip injuries in moose that, in fact, were suffering leg paralysis from the disease.
Moose brainworm
The cause of this disease eluded detection until 1964, when Canadian biologist Roy Anderson discovered it was caused by a parasitic nematode, or roundworm, commonly referred to as brainworm. The adult brainworm is about 0.01 inch in diameter, two to three inches long and is found in or near the brain.
The white-tailed deer is the normal host and is unaffected by the parasite.
Severe neurological damage occurs in several species, including moose, caribou, elk, mule deer, llamas, domestic sheep, and goats. Brainworm is found only in central and eastern North America. It has not spread to the western part of the continent, even though whitetail deer occur in much of the West.
Brainworm evolved with the white-tailed deer, which gradually expanded their range to the West but the parasite apparently did not survive the prairie conditions.
The brainworm life cycle includes the female worms in the deer’s head depositing eggs into the blood vessels of the brain. The eggs hatch into first-stage larvae while being carried to the lungs, where they leave the bloodstream and enter the air passages. Then the deer cough up the larvae, swallow them, pass them through the digestive tract unharmed and excrete them on droppings.
The first-stage larvae then infect various species of land snails and slugs that crawl over the deer droppings or soil that contains larvae.
Some species of snails and slugs are more readily infected than others, even if exposed to similar numbers of larvae.
In snails and slugs, the larvae go through second and third stages.
When a whitetail deer, moose, or other susceptible ungulate feeds on vegetation and inadvertently eats an infected snail or slug, the third-stage larvae migrate through its stomach wall, up to the spinal column, then up to the brain.
Don Cameron is a registered professional forester and a member of the Truro Daily News Community Editorial Board