Well that’s one wish that you can make come true! You can easily increase your dog’s life span by up to 2 years and it won’t cost you a thing. In fact, it will save you money! Too good to be true?
In 2019, a group of scientists published a study that looked at the lifespans of over 50,000 dogs of 12 different breeds living in North America (1). That’s a LOT of dogs! They asked a very simple question. What is the expected lifespan of dogs that are overweight when they visit a veterinary hospital in middle age (between 6 ½ and 8 ½ years) as compared to dogs that are of normal weight?
The authors defined overweight as being a 4 or 5 on a body condition scale of 1 to 5. Normal weight dogs were a 3 on that scale. The 5-point scale represented dogs that were described by veterinarians on visual examination and palpation as being very thin - 1, thin - 2, normal - 3, overweight – 4, or markedly obese - 5. Dogs in both the overweight and normal categories were then matched by breed, sex, visit age, visit year, latitude and longitude.
The authors selected dogs of a variety of sizes and from 12 of the most common breeds for this study. It is well documented that dogs that have had their ovaries or testicles removed have a lower metabolic rate and tend to gain weight unless their food intake is carefully monitored (2). Thus, it was important for the study to ensure that intact dogs were not compared with spayed or neutered dogs. After examining the data, sexually intact dogs were removed from the study given, in the authors’ words, “their relative paucity within the dataset.” This statement is certainly a concern for the future of pet dogs, but that is an entirely different topic. Nonetheless, this study only examined lifespans of spayed or neutered dogs.
For all 12 breeds of dogs, the median age at death for overweight dogs was significantly less than for dogs of normal body condition. These data are summarized in Table 1. The estimated reduction in median life span for the overweight group relative to the normal weight group ranged from 5 months for male German Shepherd Dogs, to 2 years and 6 months for male Yorkshire Terriers. Although the authors looked at only 12 breeds, the consistent finding that overweight dogs had shorter lives suggests that this effect is likely to be present in every breed.
Table 1. Mean Differences in Age at Death for Dogs of Different Breeds and Size
This study’s results are consistent with a previous study looking at lifespan in a colony of overweight vs. normal weight Labrador Retrievers (3). However, this is the first study to examine such a large number of dogs living in family environments from a large number of popular breeds (an average of >3800 dogs of each breed).
Interestingly, the difference in lifespan between overweight and normal weight dogs was greatest for the small and medium-sized dogs and less for dogs of the larger breeds. This might be explained by the demonstrated increased prevalence of fatal cancers in spayed and neutered large breed dogs (4-7; reviewed at https://www.caninesports.com/uploads/1/5/3/1/15319800/csp_-_gonadectomy_rethinking.pdf). Perhaps the increase in the prevalence of cancer in gonadectomized large breed dogs negates the effect of body condition in these breeds. Because intact large breed dogs don’t experience this increased cancer effect, their median lifespans might actually be longer than those of spayed or neutered dogs. That would have to be confirmed in another study.
Dogs that are overweight are more susceptible to a variety of chronic conditions including osteoarthritis and other orthopedic diseases, diabetes, cancer, respiratory, cardiovascular and renal disease as well as a reduced quality of life (8-15). In fact, in a recent review, the financial impact of having an obese dog was estimated to be approximately $2000 a year (16). That and the reduced annual cost of dog food for a normal-weight dog as compared to an overweight one provide significant financial incentives (in addition to the clear lifespan incentive) to keep our dogs at a normal weight.
One last point. Although it is tempting to do so, we cannot assume that the median survival ages noted in these studies are typical for these breeds. That’s because this study only included dogs that had not died before 9 ½ years of age and that continued to be cared for in the veterinary practices from which the data were obtained. That was the only way the authors could ensure accurate data. Since many dogs, unfortunately, die before 9 ½ years of age, these data show artificially extended life spans. Darn it! I sure would have loved to know that the median life span of a Golden Retriever was 13.3 to 13.5 years!
Still, the great news about this study is that we do have some control over how long our dogs live. By keeping your dog at a normal weight throughout its life, you can stack the longevity cards in your dog’s favor. If you do, when the day comes that you know it is time to say goodbye, the chances are that your dog is already much older than it would have been had it been overweight. And that’s great news!
1. Salt C, Morris PJ, Wilson D, Lund EM, German AJ. Association between life span and body condition in neutered client-owned dogs. J Vet Intern Med 2019;33:89–99. Read PDF
2. de Godoy MRC. Pancosma Comparative Gut Physiology Symposium: All About Appetite Regulation: Effects of diet and gonadal steroids on appetite regulation and food intake of companion animals. J Anim Sci 2018;96(8):3526–3536.
3. Kealy RD, Lawler DF, Ballam JM, et al. Effects of diet restriction on life span and age-related changes in dogs. J Am Vet Med Assoc 2002;220:1315-1320.
4. Torres de la Riva G, Hart BL, Farver TB, Oberbauer AM, Messam LL, McC, Willits N, Hart LA. Neutering dogs: Effects on joint disorders and cancers in Golden Retrievers. PLoS ONE 2013;8:e55937
5. Hart BL, Hart LA, Thigpen AP, Willits NH. Long-term health Effects of Neutering Dogs: Comparison of Labrador Retrievers with Golden Retrievers. PLoS ONE 2014:9:e102241
6. Zink MC, Farhoody P, Elser SE, Ruffini LD, Gibbons TA, Rieger RH. Evaluation of the risk and age of onset of cancer and behavioral disorders in gonadectomized Vizslas. J Am Vet Med Assoc 2014;244:309-319.
7. Hart BL, Hart LA, Thigpen AP, Willits NH. Neutering of German Shepherd Dogs: associated joint disorders, cancers and urinary incontinence. Vet Med Sci 2016;2(3):191–199.
8. German AJ, Ryan VH, German AC, Wood IS, Trayhurn P. Obesity, its associated disorders and the role of inflammatory adipokines in companion animals. Vet J 2010;185:4-9.
9. Lund EM, Armstrong PJ, Kirk CA, Klausner JS. Prevalence and risk factors for obesity in adult dogs from private US veterinary practices. Int J Appl Res Vet Med 2006;4:177-186.
10. German AJ, Hervera M, Hunter L, et al. Improvement in insulin resistance and reduction in plasma inflammatory adipokines after weight loss in obese dogs. Domest Anim Endocrinol 2009;37:214-226.
11. Tvarijonaviciute A, Ceron JJ, Holden SL, et al. Obesity-related metabolic dysfunction in dogs: a comparison with human metabolic syndrome. BMC Vet Res 2012;8:147.
12. Tvarijonaviciute A, Ceron JJ, Holden SL, et al. Effect of weight loss in obese dogs on indicators of renal function or disease. J Vet Intern Med 2013;27:31-38.
13. Mosing M, German AJ, Holden SL, et al. Oxygenation and ventilation characteristics in obese sedated dogs before and after weight loss: a clinical trial. Vet J 2013;198:367-371.
14. Tropf M, Nelson OL, Lee PM, Weng HY. Cardiac and metabolic variables in obese dogs. J Vet Intern Med 2017;31:1000-1007.
15. German AJ, Holden SL, Wiseman-Orr ML, et al. Quality of life is reduced in obese dogs but improves after successful weight loss. Vet J 2012;192:428-434.
16. Bomberg E, Birch L, Endenburg E, et al. The financial costs, behaviour and psychology of obesity: a one health analysis. J Comp Pathol 2017; 156:310-325.
CHRIS ZINK DVM PhD DACVP DACVSMR CCRT CVSMT CVA is one of the world’s top canine sports medicine and rehabilitation veterinarians.