These are pretty simple slip - on shoes known for the big pieces of elastic on the sides and a slip on the back to easily pull them on and off. (redreidinghood.com)
There are collars made especially for cats with a short piece of elastic sewn in. (nevadahumanesociety.org)
For cats, use a specially made safety collar that has a short piece of elastic sewn in it. (americanhumane.org)