A geriatric female guinea pig was diagnosed with a rapidly growing abdominal tumor, weight loss, anorexia, diarrhea, and lethargy. The guinea pig responded well to TCVM therapy consisting of aqua-acupuncture and oral Nei Xiao Luo Li San (Max’s Formula). She gained weight and the tumor reduced in size by 40%. When the herbal formula was discontinued by the owner due to personal illness, the tumor rapidly enlarged again. After re-instituting TCVM therapy, the tumor once again decreased in size and remained stable, affording an already geriatric guinea pig with an additional year of a good quality life before dying without warning. This case clearly documents a positive cause and effect relationship between decreased tumor growth and TCVM therapy in a species where few cases of TCVM therapy have been reported.