A 15-week-old puppy had to undergo life-saving treatment after guzzling down a double pack of chocolate biscuits.
Owner Jo Higgs returned home to find her female Rottweiler, Zeena, and the empty, chewed-up wrapper from the Bourbon biscuits.
After its stomach started to bloat she took it to PDSA Pet Hospital in Bournemouth where it was treated.
Theobromine - a chemical found in chocolate - can be fatal to pets.
Zeena had to have emergency medication after consuming 3g (0.1oz) of chocolate
Zeena has since made a full recovery.
"I'd been out on the school run and returned home to find the chewed-up, empty packet of Bourbon biscuits on the kitchen floor," Miss Higgs, from Bournemouth, said.
"I think my daughter had taken them out of the cupboard and accidentally left them on the side.
"I didn't realise Bourbon biscuits could be so dangerous for dogs, but when she started acting strangely and her tummy appeared bloated, I knew something was horribly wrong."
PDSA vet Paul Cossey said: "Just a small bar of dark chocolate contains enough [theobromine] to be fatal to a small dog, such as a Yorkshire terrier.
"Zeena had eaten 3g of chocolate, which could have killed her without treatment, as she's a puppy."
He said other foods such as grapes, currants, raisins, nuts, onions, garlic and chives could also be poisonous to pets.