next time you inject any kinds of medicine,vitamin,antibiotics,or any anti inflammatory,you need to read first the enclosed precription in every carton of medicine and also available on every sticker label of each bottle,mostly you must know if it is Intravenous,Intramuscular,Intra articular,or subcutaneous administration(site of injection),you are lucky the owner of the cat is not that kind of sensitive,firstly you are not a locum veterinary nurse,you are just a cashier.you must be aware that they can demand you in court,for short you dont have a license of locum veterinary medicine...