Published dose range
Published guidance for cats: 250 mcg per cat, every 24h.
Source: Veterinary Partner (VIN) →Same caveat: injections are standard for low-B12 cats.
If you think you overdosed
Call the Pet Poison Helpline: 855-764-7661 or ASPCA Poison Control: 888-426-4435. Both are staffed 24/7 by veterinary toxicologists.