In Horace's case they were probably not toys, as it is thought that toy theatres were first introduced as toys circa 1813,by Benjamin West.

Here is a link to a post(below) I made a couple of years ago, during the Special Topic on the L+T board, JAne Austen and the Theatre,about Toy Theatres.

Horace was very interested in the theatre of the day.There are copious mentions of attending the theatre in his letters, but I cant find any refernces to his designing stage sets in his letters or studies of his life. Sorry :-(

He did attend many private theatricals, that 18th century rage which swept the country and in which JA herself participated at Steventon ,and ridiculed in Mansfield Park.

Here he defends the Private Theatricals held at Richmond house ( the home of the Duke of Richmond, in Whitehall near the Thames in London),from ciritism:

"I am very far from tired Madam of enconmimus on the performance at Richmond House but I by no means agree with the criticism on it that you quote and which I conclude was written by some other player from envy.

Who should act genteel comedy perfectly but people of fashion that have sense? Actors and actresses can only guess at the tone of high life and cannot be inspired by it….

The Richmond theatre I imagine will take root. I
supped with the Duke at Mrs Damer's the night before I left
London and they were talking of improvements on the local as the French would say."

If you would like to see mroe examples of this type of toy theatres, which you can buy today, go here to Pollocks shop( link below), which has been saved from closure.

Hurruah and Huzzah!!!

http://www.pollocks-coventgarden.co.uk/

As to Horace and dogs, here is a quote from Tomothy Mowl's fabulous book on Horace's lifeHorace Walpole: The Great Outsider:

He was on gouty days being carried from room to room in Strawberry by his superior Swiss servants as early as 1770, when he still had 27 years to live. The power of pain to limit his ambitions and widen his sensibilitites in later life should never be underestimated. He appears, paradoxically , to have clung to youth and at the same time to have embraced old age eagerly and early....Horace inclined to cherish his own limitations and could express them freely through his pets."My poor Rosetee is dying" he wrote to Lady Ossery, who did not like dogs:

"She relaspsed into fits the last night of my stay at Nuneham ; and has suffered exquistiely ever since.You may believe I have too- I have been out of bed 20 times every night , have had no sleep and sat up with her till three this morning- but I am only making you laugh at me: I cannot help it,I think of nothing else.Without weaknesses I should not be I , and I may as well tell them, as have them tell themselves.
pp 242-3.

When Rosette eventually died he wrote a very sentimental epitaph for the dog: