It has been reported 55.8 percent of dogs in the United States are overweight,1 and this statistic has not changed in a meaningful way in years. Even more problematic is according to the Association of Pet Obesity Prevention (APOP), 18.9 percent of dogs were found to be obese.
Veterinarians can flag dogs that are overweight at routine exams by performing Body Condition Scoring (BCS). Identifying these dogs is of vital importance as they are at an increased risk for heart disease, Type 2 diabetes, inflammatory diseases, and osteoarthritis. Counseling pet owners on the nutritional management of obesity can go a long way in terms of increasing the lifespan and quality of life of our four-legged friends.
Identifying obese dogs based on BCS
During the clinical exam, veterinarians can identify overweight or obese dogs by performing BCS using a 9-point scale, as described by the World Small Animal Veterinary Association (WSAVA).2
Under ideal circumstances, the ribs are easily palpable, with minimal fat covering (4/9) or without excess fat covering (5/9). In severely underweight dogs, the ribs, lumbar vertebrae, and pelvic bones are evident from a distance (1/9) or easily visible (2/9). When examining underweight dogs, there may be an obvious loss of muscle mass (1/9) or some muscle mass loss albeit to a lesser extent (2/9).
Dogs scoring 3/9 display ribs that can be palpated, which may be visible and without palpable fat in contrast to dogs with a BCS of 4/9. The waist and abdominal tuck on these dogs would be obvious (3/9). In overweight dogs, the ribs may be palpable with slight excess fat covering (6/9) or with difficulty, due to heavy fat cover (7/9). The waist can be discernible when observed from above (6/9) or, in some cases, the waist maybe absent or hardly visible (7/9).
In dogs scoring a BCS of 8/9, palpation of the ribs may not be possible or only possible when significant pressure is applied. Further, the abdominal tuck and waist will be absent (8/9). In severely obese dogs (9/9), one can observe massive deposits of fat over the thorax, spine, and base of tail. The presence of fat deposits on the neck and limbs would be expected, along with obvious abdominal distention.
APOP has established ideal weight ranges for common dog breeds in the United States, such as Labrador retrievers (65-80 lbs), German shepherds (75-95 lbs), golden retrievers (65-75 lbs), beagles (18-30 lbs), and bulldogs (40-50 lbs).3 The percentage of body fat in dogs has also been measured using dual-energy X-ray absorptiometry (DEXA)4 and bioimpedance monitoring,4,5 although these techniques are typically used in research settings as opposed to a routine clinical setting.
Medical risks associated with obesity in dogs
Identifying dogs that are overweight or obese during routine veterinary wellness exams is of great importance, as there is significant evidence overweight dogs have reduced life expectancies. In common breeds, such as golden retrievers, beagles, chihuahuas, and Yorkshire terriers, the average lifespan reduction was found to be -0.8, -2.0, -2.1, and -2.3 years, respectively.5
Thengchaisri et al.,7studied the association between intra-abdominal fat (IAF) and heart disease in dogs. IAF was significantly higher in dogs with heart disease (23.5 + 1.5 percent) relative to healthy dogs (19.4 + 1.2 percent).
Obesity is a major risk factor for the development of Type 2 diabetes in dogs. In a clinical study involving 26 overweight dogs, German et al.,8 reported weight loss resulted in statistically significant decreases in insulin (P=0.0037) and glucose (P=0.0063).
Weight loss in dogs also led to statistically significant decreases in inflammatory markers, such as plasma tumor necrosis factor-α, haptoglobin, and C-reactive protein concentrations (P<0.05 for all).8 According to Marshall and colleagues, the prevention of obesity in dogs leads to a reduction in the prevalence of hip dysplasia and osteoarthritis of the hip, and other joints.9
One explanation for this observation is excess body weight places additional strain on the joints leading to cartilage damage. Further, obesity is associated with an elevated inflammatory state8. It is widely accepted that inflammatory mediators contribute to osteoarthritis-related pain and cartilage degradation.10
Causes of obesity in dogs
Researchers at the University of Melbourne conducted a study to investigate the opinions of veterinarians on the principle causes of obesity in dogs.11 Questionnaires were distributed to 153 veterinary practices in Victoria, Australia, and completed by 419 veterinarians.
Human-related causes of canine obesity that were given included categories such as human obesity, human-dog relationship, sedentary owner, busy owner lifestyle, owner perception of ideal weight, lack of owner education about the dog, over-pampering, affluent society, and owner ignorance. Typically, veterinarians advise dog owners to reduce the amount of food they feed their dogs, scale back on treats, and consider a change in diet.
Dietary strategies to assist with weight loss in dogs
Murphy et al.,12studied the synergistic impact of leucine and pyridoxine to promote weight loss and retain muscle mass in a 29-week randomized, positively and negatively controlled study in beagles.
Eighteen beagles were selected to undergo obesification, while six dogs were assigned to maintain their ideal weight. After the 18 beagles underwent obesification, six received leucine and pyridoxine supplementation with a canned adult diet (CAD), six dogs received placebo supplementation along with a CAD, and six dogs received a canned therapeutic weight loss diet (WLD).
Beagles receiving leucine and pyridoxine supplementation experienced decreases in weight (3.6 ± 0.9 kg) and fat loss (3.1 ± 0.6 kg) that was slightly lower than the weight (4.4 ± 1.1 kg) and fat loss (3.9 ± 0.8 kg) observed in dogs that received a WLD. However, the weight (1.1 ± 1.2 kg weight) and fat loss (0.9 ± 1.0 kg) observed in the placebo group was considerably lower relative to beagles that received a WLD and beagles that were supplemented with leucine and pyridoxine ( p < 0.0001).
Weber and colleagues13 evaluated the role dietary fiber plays in dogs undergoing weight loss. They evaluated three diets outlined below:
1) High protein [103 g/1,000 kcal], high fiber [60 g/1,000 kcal] [HPHF]
2) High protein [104 g/1,000 kcal], moderate fiber [35 g/1,000 kcal] [HP]
3) Moderate protein [86 g/1,000 kcal], high fiber [87 g/1,000 kcal] [HF]
In one study evaluating spontaneous food consumption during the first meal of the day, dogs receiving a HPHF diet consumed the fewest calories (44 kCal/kg BW) compared to HF (49 kCal/kg BW) and HP (69 kCal/kg BW). Three hours after the dogs were fed, those that received the HPHF diet consumed fewer calories (27 kCal/kg BW) than dogs that received HP (57 kCal/kg BW) and HF (41 kCal/kg BW) diets.
After dogs successfully complete a weight loss program, they are at significant risk of regaining weight. German et al.,14 studied the role of diet in preventing weight regain in 33 dogs after the successful completion of a weight loss program. The findings revealed 17out of 33 dogs continued to consume a WLD for maintenance following weight loss, while 16 of the 33 dogs were switched to a commercial maintenance diet (CMD) after the completion of a weight loss program.
In the WLD group, only three dogs (18 percent) had gained weight when they appeared for a follow-up veterinary examination, while 13 (81 percent) in the CMD group were found to have gained weight at the time of their follow-up. This underscores the importance of diet in the long-term management of obesity in dogs.
Reducing treats, avoiding overfeeding, increasing dietary fiber content, and switching from a standard commercial adult maintenance diet to a weight management diet can be very effective weight loss strategies. One key challenge is to avoid weight regain, which can happen quite easily as old habits can be very hard to break, particularly as it relates to diet.
Veterinarians must be aware of the risks for nutritional deficiencies and muscle loss associated with weight loss programs, particularly those based on commercial weight management diets. Nutritional supplementation during weight loss can help mitigate some of these aforementioned risks.
WATCH OUT FOR FRAILTY AND ATROPHY
|When placing dogs on a weight loss program, veterinarians must be aware of the risks of both nutritional deficiencies and muscle atrophy.
To examine the risk of nutritional deficiencies, Gaylord and colleagues15 did a detailed analysis of 16 adult maintenance diets (AMDs) and 15 weight management diets (WMDs). They found a large proportion of these diets contain deficiencies in vital nutrients, such as methionine, cysteine, eicosapentaenoic acid (EPA), docosahexaenoic acid (DHA), selenium, riboflavin, pantothenic acid, cobalamin, and choline.
Dogs on WMDs are also at risk for muscle loss. The risk of muscle atrophy in dogs participating in a weight loss program was highlighted by the work of Murphy et al.12 Murphy and colleagues12 reported that after 12 weeks on a WMD, obese dogs lost 4.4 + 1.1 kg. Although this weight loss was primarily due to fat loss (3.9 + 0.8 kg), 0.4 + 0.5 kg of this weight loss was due to muscle loss. Muscle loss is a major cause of frailty.16
According to Hua et al.,17 the frailty-related phenotype (FRP) in dogs is defined by five key components:
1) Chronic undernutrition
3) Low physical activity level
4) Poor mobility
Frail dogs (≥ 2 FRP components) were found to have a significantly reduced life span relative to dogs that were not frail (0 or 1 FRP components).17 Supplementation with the egg yolk-derived nutrition product, Fortetropin was shown to significantly reduce muscle loss in dogs recovering from TPLO surgery,18 and could have potential to reduce muscle atrophy in dogs undergoing weight loss.
Neerav Dilip Padliya, PhD, serves as the vice president of research and development at MYOS Corporation. Dr. Padliya manages human and veterinary clinical programs in addition to preclinical studies with leading universities and CROs to study the impact of nutrition products on sarcopenia, muscle disuse atrophy and cancer cachexia in humans and animals.
- Pitofsky, Marina. “Have you tried to help your pet lose weight? You aren’t alone as most cats and dogs in the U.S. are overweight.” USA Today. March 12, 2019. https://www.usatoday.com/story/news/nation/2019/03/12/pet-obesity-majority-us-cats-and-dogs-obese-overweight/3129342002/
- World Small Animal Veterinary Association (WSAVA), Global Nutrition Committee. Body Condition Score. https://wsava.org/wp-content/uploads/2020/01/Body-Condition-Score-Dog.pdf
- Ideal Dog and Cat Weight Ranges. Association for Pet Obesity Prevention. https://petobesityprevention.org/ideal-weight-ranges
- German, Alexander J., et al. “Comparison of a bioimpedance monitor with dual-energy X-ray absorptiometry for noninvasive estimation of percentage body fat in dogs.” American journal of veterinary research 71.4 (2010): 393-398.
- Ward, L. C., et al. “Prediction of body composition in dogs by bioimpedance spectroscopy.” Australasian Medical Journal (Online) 5.12 (2012): 708.
- Salt, Carina, et al. “Association between life span and body condition in neutered client-owned dogs.” Journal of Veterinary Internal Medicine 33.1 (2019): 89-99.
- Thengchaisri, Naris, et al. “Abdominal obesity is associated with heart disease in dogs.” BMC Veterinary Research 10.1 (2014): 1-7.
- German, A. J., et al. “Improvement in insulin resistance and reduction in plasma inflammatory adipokines after weight loss in obese dogs.” Domestic animal endocrinology 37.4 (2009): 214-226.
- Marshall, W. G., et al. “A review of osteoarthritis and obesity: current understanding of the relationship and benefit of obesity treatment and prevention in the dog.” Veterinary and Comparative Orthopaedics and Traumatology 22.05 (2009): 339-345.
- Berenbaum, F. “Osteoarthritis as an inflammatory disease (osteoarthritis is not osteoarthrosis!).” Osteoarthritis and cartilage 21.1 (2013): 16-21.
- Bland, I. M., et al. “Dog obesity: veterinary practices’ and owners’ opinions on cause and management.” Preventive veterinary medicine 94.3-4 (2010): 310-315.
- Murphy, Maryanne, et al. “Effect of a leucine/pyridoxine nutraceutical on caloric intake and body composition of obese dogs losing weight.” Frontiers in Veterinary Science 7 (2020): 555.
- Weber, Mickaël, et al. “A high‐protein, high‐fiber diet designed for weight loss improves satiety in dogs.” Journal of veterinary internal medicine 21.6 (2007): 1203-1208.
- German, A. J., et al. “Long-term follow-up after weight management in obese dogs: the role of diet in preventing regain.” The veterinary journal 192.1 (2012): 65-70.
- Gaylord, L., R. Remillard, and K. Saker. “Risk of nutritional deficiencies for dogs on a weight loss plan.” Journal of Small Animal Practice 59.11 (2018): 695-703.
- Roubenoff, R. “Sarcopenia: a major modifiable cause of frailty in the elderly.” The journal of nutrition, health & aging 4.3 (2000): 140-142.
- Hua, Julie, et al. “Assessment of frailty in aged dogs.” American journal of veterinary research 77.12 (2016): 1357-1365.
- White, Dana A., et al. “Fortetropin inhibits disuse muscle atrophy in dogs after tibial plateau leveling osteotomy.” Plos one 15.4 (2020): e0231306.