Placement of an IV catheter is much more advanced/invasive than the typical vet assistant is trained to perform. Some hospitals do not even allow vet assistants to perform venipuncture, and IV catheter placement is several steps above this in terms of skill. I am not discrediting the importance of a vet assistant, but it takes more knowledge and training than just on the job training can cover to perform an invasive skill such as IV catheter placement. If a vet assistant would like to learn how to perform skills such as these, then they should take the next step to become a licensed tech.