Pet tarantulas can pose a hairy threat

Even allegedly "safe" tarantulas can cause significant harm.

A new medical case report reaffirms why even largely non-venomous tarantulas can make questionable pets. Some respond to stress by expelling a cloud of barbed hairs that can lodge in especially vulnerable tissues. Like your eyeball.

Eye doctors at St. James’s University Hospital in Leeds, England, were puzzling over why a 29-year-old man’s apparent conjunctivitis was not responding to standard antibiotic therapy. So they peered closely into his red and swollen right eye. And found reason to doubt their initial suspicion that a microbe was to blame. Poking out of the guy’s eye were “fine hair-like projections . . . at various depths within the cornea.” Some appeared to have migrated into the eye’s interior, provoking mild inflammation there.

When they mentioned the protrusions to their patient, the proverbial light bulb went off: This guy suddenly recalled an incident that had occurred shortly before his eye began bothering him. He was attempting to clean a stubborn stain inside the terrarium in which he kept a pet tarantula when he sensed movement. As he turned to see what it was, the irritated spider “released ‘a mist of hairs’ which hit his eyes and face.”

Uh, would you have forgotten that?

When the medical team couldn’t remove the irritating hairs with a micro-forceps, they prescribed topical steroids. And after eight months, the man still suffered mild inflammation that required once-daily eye drops laced with steroids, according to Jonathan Norris, Zia Carrim and Andrew Morrell in the Jan. 2 Lancet. The good news: The patient now regularly dons “eye protection” before interacting with his Chilean Rose tarantula.

Spiderman should have known better. A British Medical Journal report published a dozen years earlier described three patients with “itchy, gritty, red eyes.” They too had run-ins with pet tarantulas, whose dartlike hairs had triggered intracorneal inflammation. One victim’s eye took three years to recover. The others were still experiencing inflammation within their eyeballs that remained “clinically active” at the time the report was written — 2 to 6 years after their spider attacks.

Andrew Blaikie of Ninewells Hospital in Dundee, Scotland, and his coauthors of that BMJ paper noted that even back in 1997, “Chilean Rose tarantulas are the most popular and widely available spiders on the market because of their hardiness, docility, and apparently harmless, non-venomous nature. They are often bought for children.”

Yet they can cause harm — what Blaikie’s team described as “devastating ocular inflammation” that can provoke serious side effects, including cataracts. Bottom line: They recommended wearing gloves if you have to handle these animals to avoid transferring any of their hairs to your skin or eyes.

Another Chilean Rose case report, this one in a 2003 issue of the journal Eye, described a four-month history of intermittent eye irritation in a 14-year-old. The boy loved his spider, despite its having “bitten him (‘just like a wasp sting’) and sprayed hairs  . . . on occasions during handling.” The boy was treated with steroids and his family informed the treating physicians that the pet was still welcome in their home.

The docs seemed a bit nonplussed, noting that the species of tarantulas that don’t rely on venom to fend off threats tend to have a nasty bite and an ability to spew a shower of barbed hairs when panicked. Not, it would seem, an ideal pet for kids — or anybody without goggles. Luckily for me, my child brought home a more conventional (if noisier) companion: a miniature long-haired dachshund.

Janet Raloff is the Editor, Digital of Science News Explores, a daily online magazine for middle school students. She started at Science News in 1977 as the environment and policy writer, specializing in toxicology. To her never-ending surprise, her daughter became a toxicologist.

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