Please help me understand my cats' behaviour last night, oh wise cat-servants. Sorry this is long...
I have two male rescue cats, litter-mates, age a year and a bit. They get on well. They were neutered as soon as they were heavy enough, so never developed noticeable tom-cat traits. (This may be relevant.)
Yesterday they had their annual vaccinations, and they did seem slightly cranky with each other in the evening but were otherwise OK.
At night, one or both of them sleep on my bed. There was a bit of tussling for the best spot on the bed last night, which doesn't usually happen.
They woke up at 5am this morning for their daily wrestling match, with its usual squeals and squeaks. As far as I can tell, this is playfighting rather than any attempt to hurt each other. But something seemed a bit different this time, so I put the light on...
...One cat was on top of and astride his brother's back, and gripping him by the scruff with his teeth. There was a bit of movement from cat-on-top that made me wonder if he was getting his rocks off on his brother. Or was he just holding him there to assert dominance? There was just something really disturbing about it and I really hope he wasn't raping his brother.
They both seem OK this morning, and are currently sitting next to each other on the windowsill, spying on the neighbours.
Was this normal cat behaviour? What did it mean? Any thoughts, please?