Obesity has become a shared health crisis across humans and many domestic animals, horses, dogs, and cats, in recent decades. Obesity is one of the biggest health threats today across humans, dogs, cats, and horses. It ranks among the leading modifiable risk factors for disease, reduced quality of life, and premature death in these species, driven by shared modern environmental factors. It was far less prevalent 50 years ago and represents a major shift with serious consequences. It is unhealthy, widely recognised as a chronic disease, and has reached epidemic proportions. Addressing it requires understanding the drivers and implementing practical, evidence-based strategies [1].
According to WHO data…
- Over 1 billion people live with obesity worldwide.
- It has more than doubled since 1990 and contributes to more than 200 health conditions, including cardiovascular disease, type 2 diabetes, cancers, and others.
- High BMI caused an estimated 3.7 million deaths from noncommunicable diseases in 2021 and is a top driver of disability-adjusted life years (DALYs)
Historical Shift: Why Wasn’t It Common 50 Years Ago?
Fifty years ago (mid-1970s), obesity rates were much lower. In the US, adult obesity was around 13-15% in the early 1960s–1970s and began rising sharply around 1976–1980, more than tripling over subsequent decades to over 40% today [2,3]. Similar upward trends are documented in pets and horses [4,5,6].
Core reasons for the rise (shared across species):
- Abundance of calorie-dense food: Global food supply increased, with more processed foods, larger portions, cheap grains/sugars, and high-fat items. For pets and horses: Commercial pet foods, treats, table scraps, and lush pastures or grain supplements replaced limited natural foraging [7].
- Reduced physical activity: Humans shifted to sedentary jobs, cars, screens, and less manual labour. Animals experienced less working roles (horses), indoor lifestyles or smaller spaces (dogs/cats), and owner-provided convenience over natural movement [8].
- Other factors: Spaying/neutering (alters metabolism), genetics, overfeeding due to misperception of ideal weight, and modern “obesogenic” environments promoting constant food access [9].
This reflects an obesogenic environment of easy calories in and low expenditure out that emerged post-WWII and accelerated in the late 20th century.
Prevalence Today: An Epidemic Across Species
- Humans: ~40.3% of US adults are obese (2021–2023), with global rates more than doubling since 1990. Over 1 billion people are affected worldwide.
- Dogs and Cats: In 2022 US surveys, 59% of dogs and 61% of cats were overweight or obese, with rates rising steadily over prior decades (e.g., increases noted in multiple studies over 10–20 years).
- Horses: 19–50%+ of leisure/pleasure horses are overweight or obese in various studies, particularly ponies and certain breeds; often under-recognised by owners. Linked to rising equine metabolic syndrome.
It qualifies as an epidemic due to rapid, widespread increases across populations and species, driven by environmental changes.
Is Obesity a Disease? Yes.
Major medical bodies classify obesity as a chronic, relapsing, multifactorial disease. The American Medical Association recognised it as such in 2013, involving genetics, neurobiology, environment, behaviour, and adipose tissue dysfunction. It is not simply a lack of willpower. In veterinary medicine, it is viewed similarly as a clinical condition and welfare issue promoting secondary diseases.
Health Consequences: Why It’s Unhealthy
Excess fat drives systemic issues. Risks compound with duration and degree of excess weight.
Shared risks: Arthritis/joint problems, diabetes (type 2 in humans/cats; linked in dogs), heart disease, certain cancers, reduced lifespan and quality of life.
Species-specific: Horses—laminitis (painful, potentially fatal hoof disease) and equine metabolic syndrome (insulin dysregulation). Pets—higher injury risk, skin issues, respiratory problems.
Bottom Line
Obesity’s rise mirrors the rise of modern conveniences but is reversible with awareness and effort. We must offer compassion because it is a disease shaped by environment, not moral failing. Success stories show improved mobility, energy, and longevity across species.
References
- Temple NJ. The Origins of the Obesity Epidemic in the USA-Lessons for Today. Nutrients. 2022 Oct 12;14(20):4253. doi:10.3390/nu14204253. PMID: 36296935; PMCID: PMC9611578.
- Giles, S.L., Rands, S.A., Nicol, C.J., & Harris, P.A. (2014). Obesity prevalence and associated risk factors in outdoor living domestic horses and ponies. Equine Veterinary Journal, 46(3), 329–334. https://doi.org/10.1111/evj.12131 (PMC3970797).
- Robin, C.A., Ireland, J.L., Wylie, C.E., Collins, S.N., Verheyen, K.L.P., & Newton, J.R. (2015). Prevalence of and risk factors for equine obesity in Great Britain based on owner-reported body condition scores. Equine Veterinary Journal, 47(2), 196–201. https://doi.org/10.1111/evj.12276.
- Montoya, M., et al. (2025). Overweight and obese body condition in ∼4.9 million dogs and ∼1.3 million cats in primary veterinary care in the USA (2020–2022). Preventive Veterinary Medicine. https://doi.org/10.1016/j.prevetmed.2024.106284.
- Lee A, Cardel M, Donahoo WT. Social and Environmental Factors Influencing Obesity. [Updated 2019 Oct 12]. In: Feingold KR, Adler RA, Ahmed SF, et al., editors. Endotext [Internet]. South Dartmouth (MA): MDText.com, Inc.; 2000. Available from: https://www.ncbi.nlm.nih.gov/books/NBK278977/
- Powell, P., Spears, K., and Rebori, M. 2010, What is Obesogenic Environment?, Extension | University of Nevada, Reno, FS-10-11 https://extension.unr.edu/publication.aspx?PubID=2810
- Pet Obesity: Why It’s Rising and How to Help Your Dog, Cat or Horse Lose Weight (2025) Morris Animal Foundation https://www.morrisanimalfoundation.org/article/weight-loss-in-cats-and-dogs
