I think one of the most difficult things for a vet to do is treat their own pet. When we're treating other people's pets we can maintain a clinical detachment and concentrate on mentally piecing together the problem. Diagnosing and treating a disease requires clear thinking and a rational mindset. When you're emotionally involved it can be difficult to think that way.
A few days ago one of my dogs, Guinevere, started vomiting and acting lethargic. She was still eating so I watched her for a few days. She didn't get better but wasn't really worse. Then yesterday my wife called me and described what may have been a seizure, so I had her bring Guinevere into the office. I ran a test for pancreatitis and took some abdominal radiographs, but didn't find anything significant. She was acting a lot better, so my wife took her back home. When I got home last night she was acting very strange again. I didn't think it was bad enough to take her to an emergency clinic (I can't easily get into my practice after hours), but I was pretty worried with how weak and lethargic she acted. This morning I took her back to work with me, planning to run more tests. However, all day she acted normal, took treats from my staff and didn't seem like there were any problems. So I ended up not running further tests and brought her home. She's still a little quite, but much better than she was yesterday.
But the point of this isn't to diagnose my dog. This was one of my hardest cases, but because of the emotional investment. Guinevere is a sweetheart and an integral part of our family. She's also my wife's baby and the two share a close bond. Not only was it hard to see my own dog sick, but my wife was worried and crying which made it even worse. There were so many emotions running around that it was hard for me to maintain that clinical detachment. And since I couldn't make a specific diagnosis and she wasn't reacting or responding like I expected, I was worried that I wouldn't be able to make her better.
Thankfully she seems much better so something must be working its way through her system. And my wife is much better since Guinevere is on the road to recovery. All of which makes me feel better. Vets can have emotional dilemmas with their own pets, as we're only human too.