Golden Retriever study examining cancer, neuter status, obesity

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Preliminary results relating to cancer, neuter status, obesity, and other research areas are just starting to come in for the Morris Animal Foundation’s Golden Retriever Lifetime Study of cancer and other conditions over the lifetime of Golden Retrievers.

Dr. Missy Simpson, epidemiologist for the study, presented the session “Overview & Analysis: Updates from the Golden Retriever Lifetime Study” at the yearly conference of the American Animal Hospital Association, March 31 through April 3 in Austin, Texas.

Strive is one of about 3,000 dogs in the Golden Retriever Lifetime Study. (Photo by Nicole Wiebusch)

The goal of the prospective study is to determine the risk factors for four primary outcomes—osteosarcoma, mast cell tumor, hemangiosarcoma, and lymphoma—and certain secondary health outcomes over the life course of Golden Retrievers. Dr. Simpson said, “One of the big advantages of this type of study design is that we’re collecting data in real time, so we know that our exposures preceded disease.”

Morris Animal Foundation launched the study in 2012 and completed enrollment in March 2015 of 3,044 Golden Retrievers age 2 or younger. As of Dr. Simpson’s talk, 2,998 dogs remained. Twenty-three died, and 23 were withdrawn from the study by owners.

The current primary outcomes are 20 cases of three of the types of cancer—lymphoma, hemangiosarcoma, and mast cell tumor—with six deaths in these cases.

Dr. Simpson is presenting a research abstract on “Overweight/Obesity in Golden Retrievers as a Function of Neuter, Age, Activity Level, and US Region” at the June forum of the American College of Internal Veterinary Medicine.

At the AAHA session, Dr. Simpson said the study dogs’ mean body condition score is 5.4 on a scale of 1 to 9. Considering a score of 5.5 or above as overweight, 29 percent of the dogs are overweight. About 2 percent are already obese, at a score of 8 or 9. About 21 percent of sexually intact females and 22 percent of sexually intact males are overweight, while 37 percent of spayed females and 44 percent of neutered males are overweight.

“Older age at spay-neuter is protective against being overweight,” Dr. Simpson said. Overweight dogs were spayed or neutered at a mean age of 9.4 months, in comparison with 10.3 months for dogs that are not overweight.

More active dogs are less likely to be overweight, but there are no regional differences in dogs being overweight.

The generalizability of the Golden Retriever Lifetime Study is uncertain. Dr. Simpson noted that the population of dogs is a highly selected set of purebred Golden Retrievers with highly motivated owners and veterinarians.

Among the future directions for the study are examining the association of nutrition and obesity with the primary outcomes of the four types of cancer and the association of reproductive hormones with the primary outcomes. Dr. Simpson was taught that neutering is a panacea, but she asked, “Should we spay and neuter as much as we are, and if so, when?”

Morris Animal Foundation is conducting the Golden Retriever Lifetime Study as the first initiative in the Canine Lifetime Health Project. Information about the project and the study is here.

Related JAVMA content:

Taking on cancer (Jan. 15, 2014)

Study shines spotlight on neutering (Nov. 1, 2013)

Study finds neutering-disease link in Golden Retrievers (April 1, 2013)