She graduated from Glasgow Vet School in 1992, then began her veterinary career as a mixed practitioner in Biggar, Lanarkshire.
This was followed by a spell at the Royal (Dick) Veterinary School, then a return to mixed practice for several years in Northern England She joined the Animal Health Agency in 2008.
Middlemiss was awarded a visiting professorship[3] by Harper Adams University in 2019.
She was appointed Companion of the Order of the Bath (CB) in the 2023 New Year Honours for services to the veterinary and farming sectors.
[5] She also endorsed the contentious decision to seize and kill Geronimo the alpaca after he had tested positive for bovine tuberculosis, to protect commercial cattle herds.