Dr Holdstock graduated from the Cambridge Veterinary School in 1991. She then worked at Rossdale and Partners, Newmarket, obtaining her PhD in Equine Perinatal Medicine and a certificate in internal and stud medicine.
In 2000 she was awarded a clinical lectureship at Cambridge. Since 2004 she has been a recognised Specialist in both Equine Internal Medicine and Stud Medicine, and has performed Expert Witness work.
Dr Holdstock has also been chief examiner for the RCVS certificate and was on both RCVS and European Educational Boards. She has special interests in fetal/neonatal health and critical care, ultrasonography, and artificial insemination. She has also worked in exotic medicine involving several endangered species breeding programmes. She organises an annual course on Wildlife Game Capture held in South Africa.