One of the key points of attempting to deal with coronavirus is social distancing, and this affects all of us, including vets. With this in mind vets are trying to reduce seeing people to an absolute minimum. In other words, emergencies only. So what constitutes an emergency? That's always difficult, and a lot is about experience. A person with many years in dogs would have seen much and would probably not turn a hair at things which could cause almost panic in a person on their first ever dog! Try to think along the lines of, "If this had happened to me, rather than to my dog, would I be rushing to A&E, waiting to see what it's like tomorrow, or sticking a plaster on it and continuing with cooking dinner?" This line of reasoning will normally stand you in good stead.