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My dog, a 4-year-old whippet called Merlin, occasionally seems to select and eat goosegrass (Galium aparine) from a hedgerow, carefully pulling out stalks and ignoring the other plants surrounding it. Is he self-medicating, and if so, how does he know which plant to eat?

“Is my 4-year-old whippet self-medicating, and if so, how does he know which plant to eat?”

Andy Maslen, Salisbury, Wiltshire, UK

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This article appeared in print under the headline “Merlin’s magic”