Can Dogs Make You Gain Weight? New Research on Adenovirus 36

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For years, obesity has been framed as a condition shaped largely by diet, exercise, and genetics. However, emerging research suggests an unexpected factor may also play a role: viral infection. A recent study from Chwirot et al. (2025) at Wrocław University of Environmental and Life Sciences has investigated whether dogs might be carriers of adenovirus 36 (HAdV-D36); this virus has been previously linked to obesity in humans and animals. Could adenovirus 36 influence weight gain in dogs and their guardians? Should we be concerned about viral transmission? And could this new evidence open new avenues for obesity treatments?

The study and its findings

Adenovirus 36 has been studied for decades, with some research indicating that people carrying antibodies to the virus tend to have a higher Body Mass Index (BMI) than those not exposed (Arroyo-Xochihua et al., 2025). In animals, infection with HAdV-D36 has been shown to increase fat accumulation, even without an increase in food intake (Liaci et al., 2025). Yet, research on whether companion animals like dogs could carry this virus has been scarce until now.

Chwirot et al. (2025) conducted this study in Poland with 118 dogs of different breeds, ages, and sexes, having recruited the participants from veterinary clinics. Using advanced laboratory techniques, including transmission electron microscopy (an analytical technique that utilises a beam of electrons transmitted through a very thin specimen to create high-resolution images) and immunofluorescence (a light microscopy-based technique used to detect and localise specific biomolecules within cells or tissues), the scientists tested blood samples for signs of previous exposure to adenovirus 36.

Their findings were unexpected: 67.7% of the dogs tested had antibodies against adenovirus 36, indicating past exposure to the virus. This infection rate is higher than that reported in many human studies, which raises the question of whether our pet dogs act as reservoirs for the virus…

The short answer? There’s no definitive evidence yet.

Adenovirus 36 spreads primarily through respiratory droplets, like the common cold or flu. Some studies have suggested that humans can transmit the virus to one another, but there has been little research on the possibility of cross-species transmission. This new study confirms that dogs can harbour the virus but does not prove they can spread it to humans. However, it does highlight that adenovirus 36 has a broader host range (multi-species) than previously thought. So, while there is currently no direct evidence of transmission from dogs to humans, the study shows the need for further research to explore this.

What does this new research mean for you?

Although the Wrocław University research has raised questions, you need not worry. The presence of adenovirus 36 in dogs does not mean they will become overweight, nor will they necessarily spread it to their humans.

The best way to help support your dog’s health is to focus on:

• Providing regular exercise appropiate to their age, breed, and health status, along with balanced nutrition. Check out my book Playing With Your Dog which helps support both body movement and brain games.
• Keep up to date with your dog’s veterinary check-ups to monitor your pet’s weight and overall health.
• Stay informed about the best ways to promote overall wellness, such as positive reinforcement-based training, quality rest, and uninterrupted sleep.

The link between adenovirus 36 and obesity is still debated in scientific circles.

Some studies suggest that infection with HAdV-D36 alters metabolism, increasing fat accumulation even without changes in food intake (Manríquez et al., 2024). Others indicate that the virus alone is not a decisive factor; genetics, lifestyle, and other environmental influences (e.g., gut microbiome, exposure to certain chemicals, sleeping patterns, etc.) remain the primary drivers of obesity.

Interestingly, some research suggests there are potential benefits of adenovirus 36. A study in Viruses found that the virus may improve insulin sensitivity and reduce blood sugar levels, potentially offering metabolic advantages in some individuals (Matia-Garcia et al., 2024). Hence, this complexity underscores why more research is needed before drawing firm conclusions!

What next?

This new study helps us understand how viruses may contribute to obesity in humans and animals. If adenovirus 36 plays a role in weight gain, perhaps it could pave the way for new obesity treatments, such as antiviral therapies or vaccines targeting the virus. Also, the discovery that dogs can carry adenovirus 36 prompts questions such as how long the virus can remain active in the body. Could it have long-term metabolic effects? And, are some individuals more genetically predisposed to experiencing weight gain after infection?

While we don’t have all the answers yet, research like this is helping to reshape our understanding of obesity. So scientists are now focusing on whether adenovirus 36 truly acts as a zoonotic virus or if its presence in dogs simply reflects environmental exposure.

Key takeaways

The idea that a virus could contribute to weight gain challenges traditional thinking about obesity being simply about genetics, diet and lifestyle. While adenovirus 36 may not be the primary driver of weight issues, it appears to be a factor worth further investigation. For dog lovers, focusing on practical, evidence-based steps like regular physical and mental exercise and enrichment, healthy eating, and keeping up with veterinary check-ups remain the best strategies for maintaining dog wellbeing and weight. Meanwhile, scientists will continue to explore just how significant adenovirus 36 may be in the global obesity epidemic. So, watch this space!

References

• Arroyo-Xochihua, O., Arbez-Evangelista, C., Miranda-Contreras, E., De León-Ramírez, Y. M., Díaz-Edgar, M., Sampieri, C. L., Arroyo-Helguera, O., & Álvarez-Bañuelos, M. T. (2025) Adenovirus 36 Seropositivity Is Related to Inflammation and Imbalance Between Oxidative Stress and Antioxidant Status Regardless of Body Mass Index in Mexican Population. Current Issues in Molecular Biology. 47(3), 166. https://doi.org/10.3390/cimb47030166
• Chwirot, A., Migdał, P., Magdalena, F., Stygar, D., Kublicka, A., Michalczyk, K., Napierkowska, Uchańska, O., Matczuk, A., Rączkowski, W., Bażanów, B. (2025) Dogs are a susceptible species to human adenovirus 36 infection: New insights into the host range of the virus causing infectious obesity. Veterinary Microbiology. 302, 110369. https://doi.org/10.1016/j.vetmic.2025.110369.
• Liaci, A.M., Chandra, N., Vodnala, S.M., Strebl, M., Kumar, P., Pfenning, V., Bachmann, P., Caraballo, R., Chai, W., Johansson, E., Elofsson, M., Feizi, T., Liu, Y., Stehle, T.,  Arnberg, N. (2025) Extended receptor repertoire of an adenovirus associated with human obesity. PLoS Pathogens. 21(1): e1012892. https://doi.org/10.1371/journal.ppat.1012892
• Manríquez, V., Brito, R., Pavez, M., Sapunar, J., Fonseca, L., Molina, V., Ortiz, E., Baeza, R., Reimer, C., Charles, M., Schneider, C., Hiroyuki Hirata, M., Dominguez Crespo Hirata, R., Cerda, A. (2024) Adenovirus 36 seropositivity is related to the expression of anti-adipogenic lncRNAs GAS5 and MEG3 in adipose tissue obtained from subjects with obesity. International Journal of Obesity. 48, 1414–1420. https://doi.org/10.1038/s41366-024-01555-x
• Matia-Garcia, I., Ocampo-Galeana, J. A., Muñoz-Valle, J. F., Soñanez-Organis, J. G., González, R. A., Guzmán-Guzmán, I. P., Marino-Ortega, L. A., Parra-Rojas, I. (2024) An Observational Study Suggests That Natural HAdV-36 Infection Decreases Blood Glucose Levels without Affecting Insulin Levels in Obese Young Subjects. Viruses. 16(6), 922. https://doi.org/10.3390/v16060922