Menzies is a professor emerita in ruminant health management and has focused her research broadly on control of disease in sheep and goats.
Her research activities include gastrointestinal nematode parasitism, Q fever, Cache Valley virus abortion, mastitis, maedi visna, caseous lymphadenitis and other "iceberg" diseases as well as some nutritionally related diseases.
She is active in the WOAH UN-FAO Peste des Petits Ruminants global eradication programme.
Menzies is currently the president of the International Sheep Veterinary Association, secretary of the European College of Small Ruminant Health Management and board member of the International Goat Association.