Dr. Nelson is the Hospital Director of the VCA Animal Medical Center of N.E. Alabama in Anniston, AL and has been in private practice for 45 years. He was first elected to the board of American Heartworm Society in 2001 and has served as the Society president (2004-2007), Symposium Co-chair (2010-2013) and currently is chair of the AHS research committee. In 1997-1998, after doubting the validity of the incidence of heartworm in cats, he conducted his own study by performing necropsies on 259 cats to determine true incidence. This study determined there was a higher prevalence of heartworm than feline leukemia or AIDS on the upper Texas Gulf Coast and that there was no correlation between heartworm and AIDS.

Dr. Nelson continues to be involved in heartworm research and was a principal investigator in an AHS funded study which resulted in peer reviewed article published in Parasites & Vectors titled Effects of doxycycline dose rate and pre‑adulticide wait period on heartworm‑associated pathology and adult worm mass. Dr. Nelson had another paper published in 2024 titled Evaluation of feline heartworm disease based on gross necropsy, serology, pulmonary histopathology, and radiographic evidence in adult shelter cats in Northeastern Alabama that sheds light on the pit falls of diagnosing heartworm disease in our feline patients. He is the lead author of the Heartworm Society Guidelines, has authored or coauthored over 30 papers and contributed four chapters to textbooks on the subject of heartworm disease.