Professor Balthazar: Doctor Don't Litt(1972)

One morning, Tom’s dad the vet has had enough of it and goes fishing. Little Tom decides to replace him in his job at the zoo. When a lion is in urgent need of an ice-cream, Tom sets out to buy it, but he leaves his things in the cage. The guards think he was eaten by the lion and overall panic follows. Luckily, Professor Balthazar is here.