Hi G.,
My advice will probably not settle well with most people but this is one area in which I have alot of experience (of a sort) and feel strongly about. First I will tell you what I learned during my months of researching and developing a pet loss/grief kit for two vet clinics that I worked for for years. One was an emergency clinic, where pets often died unexpectedly and the other was a large day practice where we did many euthansias. Second, my experience in this area as a parent has yet to come but it will soon as one of our ferrets has cancer and will not live that much longer. But I will happily share my ideas and fears about the whole process with you.
The decision to make these kits came from the observations of the entire staff of both clinics. We saw so many people trying to hide or deny their grief not only from the children but from themselves as well. It was devastating to see people in such torment with no way to help them and to have children years later come back angry at us for not telling them the truth about their beloved pet's death (after their parents had lied to them about and then they discovered the truth). The two biggest things that I discovered after my research and talking with grief counselors are to not hide the death from the child(ren) and to allow and help them express their grief, as that is the only way that they will heal. Your daughter needs to be there if you euthanize or at the very least have the chance to be with the body, experience what death means (none responsive to her and lying very still and at peace) and say goodbye if she can. I do realize that she is only 18 months old but that is another reason that she needs to experience it for herself, words alone will not make sense to her. Death is a part and fact of life. Hiding the dogs death by telling her that he/she ran away or what have you just leaves the hope of return and does not truly allow your daughter the chance to understand and grieve. It will not be easy for any of you but it will less confusing. (May I add that if you choose to euthanize and have your daughter in the room while the injection is being given than please make sure that the veterinarian understands your desires before you go in. Also, it is probably wise to have the vet sedate the dog first before the euthansia solution is given. Most vets do this automatically but not all. The sedative reduces or eliminates the post euthansia jerks and such which can be very distrubing to see but are natural.) To help your daughter with her grief you can go get a book like "Dog Heaven" by Cynthia Rylant or "For Every Dog an Angel" by Christine Davis or both. That way you have something to read to your daughter when she is feeling sad. Also, talk with your daughter about how you are feeling so that she can feel that she is not alone in her grief. There are also books out to help children understand death in gentle ways like "The Fall of Freddy the Leaf" by Leo Buscaglia. If you search for these books on Amazon.com others that are similar in content will come up so you can have some choices. Their are also resources on the web. You can try www.aplb.org or just do a search on pet loss and grief/bereavement. Alot of sites have some info but also products for sale, like urns, plaques, angel pins, etc. Also their are counselors (or support groups)who specialize in grief (some even specifically with pet bereavement) whom you may be able to get some other ideas for your daughter from.
Now, as a mom of a 2 and 1/2 year old, I have to say I am not looking forward to the day that I have to read these books to my son but it will come over and over as we have 6 pets. One thing that I am hoping to be able to do for him is to have a book of pictures of him and Loki - the ferret. That way he has a tangible way to remember himself with Loki as they played and such. There really aren't any books for ferrets like dogs and cats that I have found so I was hoping to kind of make one myself using pictures we already have of the two of them. The other thing I thought we might do if we decide to euthanize would be to make the appointment later in the day and do all the things that they love to do together and let my son feed him all his favorite treats. Make it Loki's special day and take plenty of pictures for the book. Maybe those would help your daughter as well, I don't know.
My fears are that I won't be able to convince my husband that our son should be present. He worked in a vet clinic for years as well but still seems to want to try to protect me in any way he can, even though I am an adult, when we have lost pets. I fear that that drive in him will only be increased with our son. I also worry that I won't be able to help my son deal with his grief effectively. Mostly, I am concerned that I might not pick up his need for support before he starts acting out. I know that is it pointless to worry so I try to just let that go and think of ways that I might help him. That way if I try something and it doesn't seem to work than I will have other things to try.
My Best Wishes for you and your family and Good Luck!
S.