Kellam graduated in 2006 from Massey University in New Zealand. After several years in general practice, he traveled to the UK to complete the RCVS Certificate in Veterinary Ophthalmology in 2011. He completed his Masters in Veterinary Science in 2017 at Massey University. In 2018 Kellam completed his alternative track residency at the Veterinary Ophthalmic Referrals clinic in Adelaide, Australia. In 2019 he obtained the title of Diplomate of the ECVO. Kellam is based in clinical practice in Wellington, New Zealand. He also does some clinical work in Adelaide, Australia.