According to “Lov om dyrlægegerning”/Danish Law on Veterinary Practice, the words “diagnosis” and “treatment” is reserved for vets.
Therefore anyone working with Animal Osteopathy in Denmark, who aren’t vets, are not allowed to use those specific terms about their work – however, they are allowed to practice, but need to use a different terminology. Words as “evaluation” and “therapy” are usually used about the osteopathic work.
There is no law or any regulations telling what non-vets are allowed to do in Denmark, only the above mentioned law says something about what is reserved for vets. The law is supplemented with verdicts and official interpretations stating that is not allowed for non-vets to practice acupuncture (anything the penetrates the animal’s skin) or manipulate (HVLTs and toggles).
The Danish Law on Veterinary Practice can be found here: https://www.retsinformation.dk/eli/lta/2020/40
The Danish Veterinary Association is: https://www.ddd.dk/