New to veterinarians, what to expect?

I had a flock of three Black Australorp hens previously – Mary, Bertha, and Percy. They are all about 3-4 years old. Two died. Mary died of, I suspect, reproductive issues. Bertha died of respiratory illness last Tuesday. I have only one hen left now - Percy. I suspect she is sick because her behavior was changing before Bertha died;  Percy’s behavior is like Mary’s before she died. About a week to two weeks before Mary died, she had begun to sit down more often. We did notice this, but we were so worried about Bertha that we did not think about it enough. About a week or so before Bertha died, Percy has started to sit down slightly more often than before, and also, she stopped laying eggs a few weeks ago. She is also very quiet now. She has been eating and drinking normally. She eats primarily a complete feed (Purina Layena layer pellets) and water. I hardly ever give my birds treats. When I do give treats, I feed them apple, or yogurt with garlic and ginger. Her poop is normal – it is not bloody or runny. In the past, Percy had bumblefoot and dry fowl pox on her comb and wattles. These two conditions resolved themselves without issues, so they never got very bad. I will try taking her to the veterinarian soon to see if anything is wrong with her. I have never taken my hens to a veterinarian before, so I was wondering what can I expect? What kind of documentation/papers/ information do I need to provide the veterinarian? Will my chicken be kept longer so they can run tests? What kinds of questions will the vet ask? I would also like to ask about euthanasia. Is it possible that they can put her down without my consent? Or do they only put chickens down after test results show that they have a really bad disease?

Hello and I'm so sorry that you found yourself in this situation.  In general, the answers to these questions probably very with the area / country / state that you are in, but I can help a little.  The vet may well want to know about husbandry;  about how the hens live when they are at home; in what housing, with how many animals and how they are mixed.  They will want to know their age, why they are kept e.g. are they in lay, and when signs were first noticed.  In the UK, vets generally wouldn't euthanase a chicken without your consent; however, I quote form the RCVS:    If, in the opinion of the veterinary surgeon, the animal's condition is such that it should, in its own interests, be destroyed without delay, the veterinary surgeon may need to act without the owner's consent and should make a full record of all the circumstances supporting the decision in case of subsequent challenge ...  However, such cases are relatively rare and tend to be extreme.

My apologies, I will repet some of that with typos corrected and add a little more: Hello and I'm so sorry that you found yourself in this situation.  In general, the answers to these questions probably vary with the area / country / state that you are in, but I can help a little.  The vet may well want to know about husbandry;  about how the hens live when they are at home; in what housing, with how many others (roughly) and how they are mixed.  They will often want to know their age, why they are kept e.g. are they in lay, and when signs were first noticed and more.  If you can't answer all the questions however, they will often do their best with the information that they have.  In the UK, vets generally wouldn't euthanase a chicken without your consent; however, I quote the RCVS (UK vets' regulatory body):    If, in the opinion of the veterinary surgeon, the animal's condition is such that it should, in its own interests, be destroyed without delay, the veterinary surgeon may need to act without the owner's consent and should make a full record of all the circumstances supporting the decision in case of subsequent challenge ... such cases are relatively rare and tend to be extreme.  Furthermore, some diseases are "notifiable" and special regulations are attached to their treatment; if this is ever the case, your vet ought to fully inform you.  Again, the rules about this will vary between countries and states. The best person to ask is therefore your vet, preferably before you set off.  Remember that there is no such thing as a stupid question; vets will tend to want to help you.  If euthanasia appears to be appropriate, vets will usually tell you on what grounds and if no extraneous circumstances are involved (I'm thinking suffering, notifible coditions or welfare issues), they should always talk a possible euthanasia through with you and take clear consent.

Wishing the best of luck to you in this difficult case and I would be interested to hear how you got on.