You’ll see a lot of speculation on why adult cats can flop over when they are first placed in a harness. The Catster website claims that it is a reaction to being ‘grabbed by a predator’. I disagree. It does not make sense as cats, if possible, very strongly defend themselves with their formidable weapons when grabbed by a predator.
My considered theory is stated in the infographic below. It is based on the great similarity between the ‘harness flop’ and the ‘kitten reflex response‘ when a mother picks up and carries her kitten by the scruff. The harness triggers a version of this response in my view and there may be an added physiological response as stated.
An adult cat will be confused when first placed in a harness, which will also have an impact. And there is a similarity with the ‘Thundershirt‘. A device which calms dogs and cats through pressure on the flanks. I believe that there is an overlap her in the physiological chain of events that occur.
