A quick check and I found we got linked to from this article on 21 Times “Harry Potter” Was The Cleverest Book Series Ever.
It seems that one of the foreshadowing plot clues buried inside Harry Potter is the fact Ron Weasley's "patronus" is a Jack Russell terrier:
Jack Russell terriers were bred as hunting dogs to chase vermin, such as rats, badgers, foxes, and otters. The name “terrier” means “earth dog”, as these dogs would chase badgers and foxes into their burrows, and otters across water.
And what was Hermione Granger's "patronus"? None other than... an Otter!
I am not sure that a Jack Russell terrier and an otter are destined to have a happy marriage together, but what do I know? I'm a stupid Muggle!