The animal care staff at the El Paso Zoo have received a biopsy report indicating a mass in 49-year-old Asian elephant Juno’s right mammary gland appears malignant, meaning the cells in the mass are exhibiting cancerous characteristics.
These results come after several months of close observation and multiple diagnostic procedures. Since receiving the biopsy results, zoo veterinarians have been actively researching safe treatment options and consulting with national elephant health experts to determine the best course of action.
“Cancer of any kind is extremely rare in elephants,” said Zoo Veterinarian Dr. Victoria Milne. “There is no record of a malignant mammary gland tumor ever reported in all of the veterinary literature or in the collective veterinary knowledge.”
Since there is not any veterinary literature or research on mammary gland cancer in elephants, there is no way to predict if or how Juno’s mass will progress. Using existing techniques for determining the possible spread of cancer, such as ultrasounds and X-rays, is not an option because of Juno’s size.
“When a human is diagnosed with cancer, treatment decisions are based on the results gathered from very specific test results and a long history of thousands of cases and outcomes,” said Milne. “For elephants, none of that information exists. So, while the mass looks malignant on a microscopic level, there is no way to be sure what will happen next and there is no previous treatment experience to guide us.”
As the El Paso Zoo veterinary staff continues investigating viable treatment options, some known factors they are continually taking into consideration are the high risks of anesthesia and surgery in geriatric elephants, and elephants’ frequent difficulty in healing from surgical procedures.
“Currently, there are no verified safe treatment options, and only one team has previously performed an elephant mammary gland removal,” said Milne. “No one knows how harmful this mass may or may not be to Juno’s health, but we do know that all of the traditional cancer treatment options could be highly damaging. Healing from this kind of invasive surgical procedure could take up to two years because elephant surgical wounds very frequently become infected and have delayed healing – and it could be incredibly difficult for Juno.”
The El Paso Zoo is taking a conservative approach while continuing to gather additional information. Because of the extreme rarity of cancer in elephants, national elephant experts, including Dr. Michele Miller, Association of Zoos & Aquariums Species Survival Program veterinary advisor, are being consulted. At this time, there are not any elephant health experts who are recommending surgical removal of the mass.
“Surgery in elephants is a serious decision. Healing is often slow and can result in other problems such as infection,” said Miller. “In Juno’s case, it seems prudent to take a more conservative approach to minimize any discomfort and complications associated with surgery.”
Zoo veterinarians and keeper staff are continuing to carefully monitor Juno’s overall health and wellbeing.
The Zoo’s veterinarians will be consulting further with veterinary cancer treatment specialists and the veterinarians who performed the one known previous elephant mastectomy procedure. These additional insights and recommendations will assist staff in creating the best care plan for Juno.
“Our main concern is Juno’s welfare, wellbeing and stress levels,” said El Paso Zoo Director Steve Marshall. “Each of these factors will be constantly taken into consideration when exploring potential treatment options.”
Asian elephants are endangered according to the International Union for the Conservation of Nature (IUCN) Red List, the classifying authority for species worldwide. Both of the Asian elephants at the El Paso Zoo are elderly, with ages beyond the average life expectancy for Asian elephants.
The El Paso Zoo contributed to this article.