Thomas, 77, called emergency services and grabbed a pole to try and help her friend. She said: “I thought well, I’ll put that out in the water and hook her or hit him, and... she was not there any more.
“I couldn’t do anything. I couldn’t get in the water. I never woke up this Monday morning and thought I would be watching someone die.”
The dog survived the attack, but Serge succumbed to her injuries, the Florida Fish and Wildlife Conservation Commission said.
A police helicopter helped locate the alligator in the lake and trappers later dragged it out. They estimated that it weighed between 600 and 700 pounds.
Fatal alligator attacks are rare, but there have been two deaths in the last year in Florida.
In May, authorities found the body of a 47-year-old man who had been retrieving Frisbees from a lake in Largo, and in July an 80-year-old woman was killed by two alligators after she fell into a pond near her house in Englewood.
According to the Florida Fish and Wildlife Conservation Commission, there have been 442 unprovoked alligator bites on humans, including 26 fatalities, between 1948 and 2021.
The chance of a person in Florida being injured in an unprovoked alligator attack is about one in 3.1 million, according to the commission.
Once on the endangered species list, the alligator has recovered to a point at which wildlife officials estimate the Florida population at more than 1.3 million.