Kadie, a female German shepherd mix, presented at 113 lb. with multiple ligament tears and needing a hip replacement. At the end of her weight-loss program, she weighed 80 lb. and could walk unassisted. Photos courtesy Dr. Angela Rollins The rate of obesity in the United States has reached alarming levels and continues to climb, reports the Centers for Disease Control and Prevention (CDC).1 An estimated 100 million American adults have obesity, defined as a Body Mass Index of 30.0 or higher, the agency notes, and 22 million adults have severe obesity, defined as a BMI of 40.0 or higher. Pets, too, are at risk of obesity, and their rates are rising, as well, say researchers.2 The Association for Pet Obesity Prevention (APOP), for example, estimates 60 percent of dogs and cats in the U.S. are either overweight or obese.3 Educating clients on proper pet nutrition and the importance of regular exercise are essential steps in managing pet obesity, but researchers are hoping to make the process even easier with the development of glucagon-like peptide 1 (GLP-1) drugs similar in function to human weight-loss medications. “Obesity in cats and dogs is quite prevalent in the United States and has tracked the human rate of obesity. As people get fatter, our pets seem to get fatter, too,” says Dottie Laflamme, DVM, PhD, ACVIM (Nutrition), who spent 30 years in research and development at Purina, studying pet nutrition, including the issue of canine and feline obesity. The first prescription weight-loss drug for dogs was Slentrol (dirlotapide). Released by Pfizer Animal Health in 2007, it worked by reducing fat absorption and increasing a sensation of satiety. Slentrol was withdrawn from the European market by the European Medicines Agency as a result of difficulties4 with administration and potential side effects, including diarrhea, vomiting, and lethargy. The drug was eventually discontinued in the United States due to lack of interest among pet owners and other issues. “We found that pet owners didn’t like Slentrol because their dogs weren’t as excited about their food,” says Angela Rollins, DVM, PhD, DACVIM (Nutrition), a clinical professor at the University of Tennessee College of Veterinary Medicine (UTCVM) in Knoxville and a member of the UTCVM’s Veterinary Obesity Center. “Since seeing your pet with a good appetite is such an emotional bonding part of pet ownership, it was difficult for pet owners to wrap their heads around the fact they didn’t eat as much.” Promising research Today, San Francisco-based OKAVA Pharmaceuticals, Inc. is among the players to develop a new weight-loss medication for pets. In 2021, the company reported5 the results of a proof-of-concept validation study for OKV-119, a miniature, long-term exenatide drug delivery system developed under a partnership with Vivani Medical, Inc. The validation study, published in Frontiers in Veterinary Research, demonstrated long-term drug delivery can be achieved in cats with Vivani’s proprietary drug delivery system.5 It also demonstrated OKV-119 is safe and can easily be inserted subcutaneously during a routine clinical visit. A second study,6 reported in May in BMC Veterinary Research, found the technology worked effectively over even longer periods of time. “One of the greatest challenges across feline medicine for any disease is administration,” OKAVA CEO Michael Klotsman, PhD, tells Veterinary Practice News. “Cats are notoriously difficult patients that aren’t very compliant in taking daily pills. So, the clinical benefit and the patient benefit of OKV-119 technology is it’s a one-and-done solution. A single implant lasts six months. We are also planning to embark on additional studies in the near term looking at diabetes and the ability to maintain a state of diabetic remission.” The focus now is on cats, with dogs to follow, Klotsman says. “The medical need and market demand [for weight-loss medications] is much greater in cats,” he says. “With dogs, you have the ability to include more exercise, which is not necessarily available to indoor cats. But we believe the weight-loss mechanisms will also carry over into dogs.” GLP-1 drugs were originally developed as a treatment for type-2 diabetes in humans and were later found to enable weight loss by curbing hunger and slowing the movement of food from the stomach into the small intestine, making the patient feel full more quickly and for a longer period. This mechanism is not clearly understood, though it appears to work similarly in pets. OKAVA Pharmaceuticals, Inc. is not the only player in the quest to find a safe weight-loss drug for pets. Better Choice leapt into the fray in February, with the acquisition of Aimai Pet Healthco Inc., a company specializing in research and development. Better Choice intends to invest up to $1.5 million to develop a GLP-1 pet treat.7 Lucifer, a domestic shorthair, lived in a household with several other cats. He weighed 16.5 lb. at the beginning of his weight-loss program and was 10 lb. after one year of treatment. Photos courtesy Dr. Angela Rollins Diagnosing pet obesity Veterinarians diagnose obesity in animals via a qualitative nine-point body condition score, which Laflamme helped develop. A score of 4 or 5 indicates a healthy ratio of muscle and body fat, while a score of 7, 8, or 9 suggests obesity or the onset of obesity. According to APOP,8 in animals with a healthy weight, “ribs, spine, and hip bones are easily felt and may be visible (coat length, density, and texture may interfere with visibility). A waist and abdominal tuck are seen when viewed from above and on the side. Fat can be felt around ribs, spine, and hip bones.” The most common cause of obesity among U.S. pets, says Laflamme, is a combination of too many daily calories and too little exercise—the same lifestyle that causes weight gain in humans. “Exercise is a very important piece of the equation,” Laflamme says. “Most pets are indoors most of the time, and a walk twice a day really isn’t enough.” Though uncommon, hypothyroidism may also result in obesity in pets because it slows the metabolism, resulting in fewer burned calories, Laflamme adds. Issues with the microbiota in the gut, as well as genetics, may also play a role. The health risks associated with obesity are significant in both humans and animals and include heart disease, stroke, diabetes, joint issues, and even cancer. “Obesity is a huge issue for quality of life in pets,” says Rollins. “One study involving Labrador retrievers showed being even a little overweight reduced lifespan by a couple of years.” Obesity-related diabetes is probably the most significant health issue, Laflamme says. Obesity also puts a strain on the joints, so overweight pets—especially dogs—are likely to be more arthritic or risk lameness from hip dysplasia, cruciate ligament rupture, or general body soreness. “Obesity is also a risk factor for cardiopulmonary problems and even kidney disease,” says LaFlamme. “Obese pets may also experience more skin problems because they cannot groom themselves well.” Extreme obesity can also influence physical examinations in that excess body fat makes it harder for veterinarians to check internal organs or draw blood, which in turn can make diagnoses more difficult, says Rollins. Most research into obesity has focused on dogs and cats, but according to LaFlamme, obesity can afflict any species. “Animals that are cared for and over-loved by people experience the same risk factors as people. Most commonly, this includes an abundance of food and inadequate exercise.” Mabel’s story Dr. Angela Rollins has much more than years of professional experience addressing pet obesity– she has personal experience as well. Around 12 years ago, a female beagle named Goldie was brought to the UTCVM from a local shelter. At 65 lbs, Goldie was morbidly obese, but Rollins fell in love with her and adopted her on the spot, changing her name to Mabel. “When Mabel came in, she couldn’t walk,” Rollins recalls. “We did a couple of ligament repairs, but she was just pitiful.” Photos courtesy Dr. Angela Rollins Over the course of a year, Rollins worked with Mabel to lose weight, with a goal of dropping 45 lbs. “What really helped was she was in a brand new environment, so all of her old habits were suddenly gone,” she says. “I wasn’t going to sit at the table and feed her hotdogs while I’m eating my dinner and things like that. So, she learned pretty quickly what I would and wouldn’t do.” Rollins also put Mabel on a therapeutic weight-loss diet because she needed severe calorie restrictions. “I didn’t feed her for a 65-lb dog, I fed her for a 20-lb dog, and over time she lost the weight,” Rollins says. “We also got some help from an underwater treadmill, so she exercised a couple of days a week at the vet school. That helped get her mobility back.” Mabel was around four years old when Rollins adopted her; the dog passed last year at age 16. ● ‘Gold standard’ for treatment Addressing these basic lifestyle issues remains the gold standard for the treatment of overweight dogs and cats. “How that is done varies by practice and pet parent,” says LaFlamme. “If the practice is doing a good job, they’re performing body condition scores on all patients, which allows them to address weight gain before a pet becomes severely overweight. If not, then they have to deal with obesity in the later stages.” Many owners are unaware the treats and dental chews they feed their pets are high in calories, and allowing cats to “graze” on dry food throughout the day may also be setting them up for obesity, Rollins adds. She encourages veterinarians to promote enrichment activities that can help keep indoor cats more active, such as increasing vertical space and giving them controlled outdoor time. “I’m also a fan of putting dry kibble in a toy and making them hunt for their food with the toy,” says Rollins. “They have to move more if they’re trying to work the food out of the toy as opposed to a bowl. If you have a single cat, you can put little pockets of food in different places around the house and let them hunt for it during the day.” The Indoor Pet Initiative at The Ohio State University College of Veterinary Medicine in Columbus has additional resources on its website to keep housebound animals active: indoorpet.osu.edu. Addressing obesity in pets poses inherent challenges. The greatest challenge may be the lack of recognition of obesity as a disease. “I believe most people recognize obesity can be a problem, but that doesn’t mean they are going to recognize their own pet as being fat,” says LaFlamme. Ultimately, prevention should be the goal. “I’m a big fan of Waltham’s growth charts for puppies and kittens,” Rollins says. “If veterinarians and pet owners tracked their pets’ weight using those charts, and adjusted their feeding accordingly, it would ensure they stay on their curve and not go over. By the time a puppy or kitten is a year old, they should be at their ideal weight. If we could get every pet owner to do that, we could cure pet obesity.” Don Vaughan is an award-winning writer who frequently writes about veterinary-related topics. References https://www.cdc.gov/obesity/php/data-research/adult-obesity-facts.html https://www.petobesityprevention.org/2022 https://www.petobesityprevention.org/ https://www.ema.europa.eu/en/medicines/veterinary/EPAR/slentrol https://pubmed.ncbi.nlm.nih.gov/34046446/ https://investors.vivani.com/investors/news-events/press-releases/detail/173/vivani-medical-announces-publication-of-positive-weight https://www.bloomberg.com/news/newsletters/2024-06-12/dreaming-of-ozempic-style-drugs-for-fat-cats-and-dogs-prognosis https://www.petobesityprevention.org/pet-weight-check
