Vacations in Prostokvashino (Каникулы в Простоквашино / Kanikuly v Prostokvashino) is a Soviet cartoon from 1980. In British English, it is generally known as Holidays in Vacations in Prostokvashino. The cartoon forms the second of three parts of the much beloved Prostokvashino series.
You can watch all three episodes here. Each of the episodes runs a little under 20 minutes.
Uncle Fyodor’s mother is in serious need of a vacation. She is exhausted. And, besides, she has nowhere to wear her four lovely evening dresses.
Fyodor and his dad plead with her to go to Prostokvashino, but she wants to go to a seaside resort. And so, when Fyodor’s parents get on the train to go down to Sochi, he runs away back to Prostokvashino. He spends the holidays there again with his friends Matroskin the cat and Sharik the dog.