The Milwaukee County Zoo Mourns the Death of Hippo Patti

Saturday, Nov. 9, began routinely for Patti, spending time in the indoor Hippo habitat and pool. However, at the end of the day, when it was time for Patti to “shift” or switch out of her pool, she was reluctant to move. Once she ultimately came out of the pool, she appeared lethargic and was not interested in eating her dinner.

The team, including MCZ’s senior staff veterinarian, continued to monitor her closely and later that night, they observed Patti quickly declining further. After assessing Patti, the decision was made to humanely euthanize her. Patti died surrounded by her animal care team, including the zookeepers who best knew and loved her, comforting her to the very end, including rubbing her ears and feet.

At 55 years old, Patti was considered a geriatric animal. According to the Association of Zoos and Aquariums (AZA), the median life expectancy of a female (or male) hippo living in human care is 36.7 years. Patti received multiple supplements regularly and was on medications for arthritis to keep her comfortable in her advanced age. A preliminary necropsy (animal autopsy) has already been conducted, and initial results indicate severe gastroenteritis.

Weighing in at 3,000 pounds, Patti was known as the more “petite” of MCZ’s two hippos. Due to Patti’s advancing age and male Happy’s much larger size, the two hippos never shared space but did spend time together through their underwater gate, and he liked to visually follow where Patti was. The animal care team will continue to monitor Happy, but they expect him to adjust well to her absence.

Patti will be fondly remembered as an opinionated and spirited animal. Her offspring, a daughter named Puddles, was born at MCZ and died in 2013 at 37 years old. In her later years, Patti became more engaged with her animal care team and even participated in voluntary blood draws last year. She participated frequently in behind-the-scenes tours, and many guests have video and photos of her opening her mouth, waiting for them to throw food in. Patti loved all kinds of fruit — especially cantaloupe and watermelon — and enjoyed having water sprayed in her mouth. Patti would hold her mouth open for as long as her care team would keep the hose going. When the Dohmen Family Foundation Hippo Haven opened in summer 2020, Patti was reluctant to fully explore her new outdoor habitat. But in the last two years, she finally began going out and enjoying the underwater viewing pool. Patti was very curious and engaged with the public, coming over to the viewing window to watch all the guests — especially little kids.

Patti contributed to a number of research projects over the years to help improve knowledge and care of her species. And Patti’s legacy will continue to live on: Biofacts from Patti will be donated to the U.S. Fish and Wildlife Service (USFWS) Forensics Laboratory. The Wildlife Forensics Lab helps build cases that prosecute crimes involving wildlife trafficking. This hippo species is listed by the IUCN (International Union for Conservation of Nature) as Vulnerable, in part due to threats from poachers and trophy hunters.

Hippo Haven is now closed for the season as expected, due to increasingly colder temps, and is anticipated to reopen in the spring, when viewing of hippo Happy will resume. Construction of Phase III of Adventure Africa, featuring a new indoor and outdoor home for rhinos and a new indoor space for hippos, is expected to complete in fall 2025. MCZ will determine the potential transfer in of another hippo at that time.

Patti was treasured by many members of the animal care team, past and present, over the years. She will be greatly missed by Zoo guests, volunteers, and all who had the pleasure to know her during her long life here at MCZ.