Six dogs are thought to have died in Helensburgh in Argyll and Bute and one in Largs, Ayrshire, this year after consuming Hemlock water dropwort, a weed that is said to be the most poisonous in the UK which grows on marshy ground or on the banks of waterways.
Dog owner James Mac-Donald's Cairn Terrier Taggart became the latest victim of the plant when it died after chewing on some at the popular beauty spot of Tarbet on the banks of Loch Lomond last month.
Mr MacDonald said his dog passed away within an hour of eating the shrub, which is also known as poi-son parsnip, after a walk on the shoreline of the loch.
The weed's roots are par-ticularly deadly and grow into thick tubers which appear wholesome, making them attractive to dogs.
Mr MacDonald, 32, of Glasgow, said his eight-month-old pet dog was being taken for its first walk in the countryside with his partner Claire.
He said: "He was fine and was playing at the water edge and then in the undergrowth.
"We went to eat lunch on the picnic tables and I noticed he really didn't look well. It was almost as though he was inebriated and his head was listing to one side.
"It took us maybe 40 minutes to drive to the vet and he was on my lap the whole way, but when we got there I knew he had died.We're heartbroken."
Ariel Brunn, veterinary surgeon at the Dogs Trust, said the best course of action to keep pets away from harmful plants was to stick to paths and avoid letting them loose in the undergrowth.