KITCHENER — A swan that died in the Victoria Park pond in September was suffering from inflammation of the brain caused by a parasite and there was no preventing the mishap, says a Guelph-based animal pathologist.
Dr. Doug Campbell, of the Canadian Co-operative Wildlife Health Centre — part of the University of Guelph’s veterinary college — did an autopsy on the bird after it was pulled from the water on Sept. 14.
“This was an unfortunate accident that occurs just as a consequence of living in a natural or semi-natural environment,” Campbell said.
Campbell said the dead swan ingested a parasite called a schistosome, likely when it swallowed a snail.
“I have seen similar conditions in swans previously but never this severe,” Campbell said, “just in terms of the numbers of parasites and the number of areas in which there was inflammation.”
That parasite is common among gulls, ducks and geese and is harmless in those birds. Snails carry it as well and act as an intermediate host. Swans inadvertently eat snails sometimes when scooping material from the bottom of a pond.
After a swan swallows a snail with the parasite, the tiny organism emerges and burrows into surrounding tissue, typically ending up in blood vessels.
Circulating blood carries the parasites’ eggs to different parts of the swan’s body, typically the kidneys, spleen and liver, but also the brain.
“Once lodged in the brain the body responds with inflammation,” Campbell said. “What I saw with this bird, there was quite extensive inflammation of the brain in different parts of the brain.”
The autopsy report should counter two stories that circulated among park regulars following the bird’s death.
Days before the bird died, onlookers watched in horror as a homeless woman grabbed a swan by the neck with both hands and hauled the big bird from the water. Some thought she fatally injured the animal at the time.
The second story relates to water quality. After spending about $10 million on the dredging and shoreline restoration of the pond, some residents feared the bird’s death was related to poor water quality.
Campbell said nothing could be done to prevent death because the parasite is found wherever gulls, ducks and geese are found.
“So I don’t think that having schistosomes per se is indicative of water-quality problems,” Campbell said. “I guess it is a fact of life with different species of birds inhabiting the area.”
Campbell said the dead swan had likely been infected for some time because it was underweight and waterfowl are typically in peak physical shape in September.
“This bird was really quite thin and presumably had not been functionally normally for some time,” Campbell said.
People who saw the swan struggling and dying in the park were upset and complained that nobody at the city or humane society responded quickly to their repeated calls for help. But the autopsy shows nobody could have helped anyway.
“In the wild, death is rarely nice and quiet,” Campbell said. “Probably as quiet as it gets, and it’s not every nice, is when birds starve out in the winter time.
“Most wild birds, most wild life, they don’t get cared for and disease just runs its course in them,” Campbell said, “and quite honestly this was not a disease that was treatable.”
The same parasite causes “swimmer’s itch” in people. That is a minor-skin condition that almost always clears up on its own.
A city staff report based on the autopsy results is going to city councillors on Monday.
tpender@therecord.com
