it depends on how do you do it and how your partner does it. If the rectum is empty, and you use lube and relax - no mess for you.
Well being quite an expert on both areas myself I strongly suggest oral. The reason for this being that anal can get quite messy and it is harder if you are old or slow.
Sounds like she needs her anal glands expressed. While you can learn to do this at home, it's beyond my capabilities to teach this in writing (it's also not a job for the weak of heart). Go to your vet and have your lab's glands expressed -- it's painful for her (and messy sometimes too).
messy, messy, messy
Messy
mesyy like an Ausie in a bar at 3 am:p
A messy hair gel.
You're a messy pig.
The word "messy" is an adjective.
It's not really messy after you clean it out. But in middle of the week, it'll get messy and you have to clean it again.
The anal canal has a ring of muscle, called the anal sphincter
An anal sac expression is an emptying of an animal's anal glands.
The anal pore