Owner Jo Higgs, from Bournemouth, Dorset, returned home to find Zeena had eaten all of the biscuits, leaving only a chewed up empty packet.
She sought help from the PDSA Pet Hospital in Bournemouth after Zeena became unwell and her stomach bloated.
Miss Higgs, 44, said: "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.
"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 gave Zeena emergency medication to make her sick and prevent further absorption of theobromine, the chemical in chocolate that can be fatally toxic to pets.
Zeena was also put on a drip to flush any remaining toxins out of her body and transferred to out-of-hours provider, Vets Now, for close monitoring overnight.
Mr Cossey said: "Chocolate can be extremely poisonous to dogs.
"Even small amounts can be dangerous - just a small bar of dark chocolate contains enough 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.
"Thankfully, we were able to provide life-saving treatment before it was too late."
Miss Higgs said: "I was terrified she wasn't going to make it, so I'm incredibly grateful to all the team at PDSA, they were absolutely fantastic. I can't thank them enough for saving Zeena."
Mr Cossey added: "Lots of food that we consider a tasty treat can be deadly for our pets. These include chocolate, grapes, currents and raisins and some nuts.
"Onions, garlic and chives can also be poisonous, so it's important to be clued up on what your pets can or can't eat. If you think your dog has eaten something they shouldn't, speak with your vet immediately."
For further information including signs and symptoms to look out for, visit: www.pdsa.org.uk/taking-care-of-your-pet/pet-health-hub.