We have a 7 year old Jack Russell and I bought him a supposedly indestructible squeaky snake toy yesterday which he loves.
We've noticed him trying to hump it a few times though, which he rarely does any more (was neutered as a pup) and every so often he will stop playing with it and sit looking at it and whining.
He's not like this with any of his other toys so I can't quite figure out what's wrong. He does usually destroy any squeaky toy within minutes though and hasn't been able to with this one, so I'm wondering if that's why he's crying?
Any ideas? I don't want him being upset by a toy 
Thanks!