You can use a BiteNot collar link below.

https://www.amazon.com/BiteNot-BN5-Collar-21/dp/B001VPCF60?source=ps-sl-shoppingads-lpcontext&ref_=fplfs&psc=1&smid=A3FBI0739Y5O1L

Or make one yourself:

Fold a large bath towel longways into thirds. Wrap it around your dogs neck, then secure it with three strips of duct tape, wrapped completely around the towel.