The educational side of the Doctor's post office was a very important one and it grew all the time. As he had said to the Skimmer at the beginning, as soon as the birds and animals realized the helpfulness of having a post office of their own they used it more and more.  
And, of course, as Speedy had , they wrote most of their letters to the Doctor. Soon the poor man was swamped with mail, asking for medical advice. The Esquimaux sleigh dogs wrote all the way from the Arctic Continent to know what they should do about their hair falling out. Hair—which was all the poor creatures had to keep them warm against the Polar winds—was, of course, very important to them. And John Dolittle spent a whole Saturday and Sunday experimenting with hair on Jip to find a way to cure their trouble. Jip was very patient about it, knowing that the Doctor was doing it for the good of his fellow dogs. And he did not grumble—although he did mention to Dab-Dab that he felt like a chemist's shop from all the different hair oils the Doctor had used on him. He said they ruined his keen nose for two weeks, so he couldn't smell straight.
 
And besides the letters asking for medical advice, the Doctor got all sorts of requests from animals all over the world for information about food for their babies, nesting materials and a thousand other things. In their new thirst for education the animals asked all manner of questions, some of which neither the Doctor nor anybody else could answer: What were the stars made of? Why did the tide rise and fall—and could it be stopped?
 
Then, in order to deal with this wide demand for information which had been brought about by his post office, John Dolittle started, for the first time in history, courses by correspondence for animals.
 
And he had printed forms made, called "Things a Young Rabbit Should Know," "The Care of Feet in Frosty Weather," etc., etc. These ............