Remain calm. Use essential oils that are safe for dogs to help keep them calm if they are terrified of their nails being clipped.
Peace & Calming and Valor are two oils that are safe to use. Simply rub them into the tips of their ears Before, During and After trimming their nails. This will help release tension and slowly make them relaxed every time they get their nails clipped - gradually making the need for the oils less and less as they learn to trust the process.
The use of NuVet Plus will also work for anxiety to help maintain a calmer dog. Give 1-2 wafers before trimming your dog's nails. This will gradually help with continued daily use of the NuVet.
Never panic if you get the quick. Even well trained professionals do this. We try not to, but it happens. Yes you can feel bad, but the way you react will play a LARGE roll on how your dog will handle the rest of his/her nails in the future. Act as if it did not happen, apply the corn starch or Kwik Stop and continue to trim. After you are done trimming their nails, this is when you can show them empathy.
If your dog is a biter, protect yourself and use someone’s help. (Spouse, Friend etc..) Never put anyone in danger, if this is the case, PLEASE use a safe restraint that will not harm your pet. Muzzles are not abuse if used correctly and with a positive reward. If you are OK with the little nips, let them do this (however use some common sense here as well.) If the nips are small and painless, do not discipline... The best thing you can do is to completely ignore the dogs reaction. This will gradually teach them over time that you are not scared and it has no effect on you. If your dog starts to become more aggressive, follow the proper restraining method mentioned above. (the one that suits you and your dog best)