The staff at the PDSA store in Boscombe, Bournemouth, are now selling the dresses for a fraction of their usual price, with some gowns available for just £150.
Store Manager Karen Pennington said: "We were amazed by the size and generosity of this donation.
"The dresses are absolutely stunning and there is a fabulous range – something for everyone!"
Would-be brides are now travelling from far and wide to view the collection, with styles ranging from vintage lace to full-skirted princess gowns.
A range of bridesmaid and prom dresses are also on sale at a reduced price of £50.
Karen added: "These dresses will raise vital funds to help our vets and nurses save the lives of more poorly pets." The charity hopes to raise £10,000 in funds from sales.