The Misunderstood Carriage Horses of Mérida. Part I

This text corresponds to the first of two parts analyzing, based on scientific evidence, the work of the carriage horses in Mérida.

Dr. Pedro González, DVM Marcela Navarrete

Social License to Operate and the Use of Animals

 

How do people perceive the use of animals? The way a society perceives how valid it is to use animals for different purposes is known as the social license to operate (1). Important: this is not about laws or regulations. It refers to how people perceive an activity—even if they are not well informed, do not fully understand the topic, or regardless of whether it is scientifically good or bad for the animal. That is what social license to operate means.

There are animals and uses that people perceive as positive. For example, keeping dogs as pets is widely accepted, even though dogs, being highly social animals, are prone to hyper-attachment or separation anxiety when improperly handled by their owners. Keeping dogs as pets is well regarded even though some breeds have been physically altered (brachycephalic or flat-faced breeds) due to human preferences, despite the health problems this can cause.

Society rarely criticizes the use of dogs as pets, and no law fines an owner or “guardian” if their dog develops hyper-attachment or separation anxiety; only one or two countries have banned flat-faced breeds such as the pug. Of course, animal abuse is punishable by law (2), but society will not take to the streets in protest if a dog accidentally falls while getting in or out of a car, runs away and gets lost, or drools after running and playing under the sun.

However, if horses were involved, society would treat the situation differently. In other words, for certain animals and certain uses, society perceives them as negative even without scientific evidence to justify that view. For these animals, even when studies indicate that such use does not pose a risk to their welfare, public perception may suggest the opposite.

Animal Work and the Case of Carriage Horses

Such is the case of carriage horses. The word “work” seems taboo when it comes to animals, as if it were inherently wrong for an animal to perform a job. In working animals, innate characteristics of the species are utilized to obtain a benefit for humans. In other words, we make use of the animal’s natural capacities to perform a given activity (3).

This does not mean that the animal would naturally perform that behavior on its own. No dog would naturally enter a collapsed building to search for a person who is not its owner—yet rescue dogs do exactly that. What is utilized are the animal’s physical, social, and emotional capacities, which can be directed toward an activity without causing overexertion.

For example, due to their body structure and musculature, horses can pull carriages without this representing a threat to their welfare (4).

Working Dogs and Social Perception

Another example is the number of olfactory cells that all dogs possess (except flat-faced breeds such as the pug, which struggle to breathe), a capacity that is used in tracking dogs. They can also detect diseases such as COVID-19 and support children with diabetes by alerting them when they need insulin. In all these activities, dogs are working.

The innate behavior of stalking and herding prey in groups—as seen in breeds such as the border collie or the Australian shepherd—is also utilized: these are herding dogs, and they are working animals as well. Emotional support dogs also perform work.

When it comes to dogs, society does not perceive using them for work as negative. Almost no one looks down on someone whose job is to rescue missing persons under rubble with the help of a dog. Nor are people criticized for making a living training dogs to remain calm under conditions that might be stressful for their future guardians—that is, preparing emotional support dogs. All these jobs are seen as legitimate ways to earn income.

The Perception of Carriage Horses’ Work

However, the work of carriage drivers—conducting tourist rides using horses to pull a carriage—has been demonized. This activity is perceived differently from tracking dogs.

In both cases, tracking dogs and carriage horses, animals are used to earn money (dog trainers must also charge for their services in order to make a living). In both cases, the animals are cared for, fed, provided with veterinary checkups, comfortable housing, and everything necessary to perform their tasks without compromising their welfare. Even so, society seems to judge working dogs and working horses by different standards.

Scientific Studies on Mérida’s Carriage Horses

In this article, we explain in simple terms the results of our published scientific studies on Mérida’s carriage horses. It took us more than five years of research, and we do not intend to tell people what is right or wrong—only to provide solid information so that each person can form their own informed opinion.

Key Differences Between Horses and Dogs

The first thing to understand is that a horse is not a dog (5). In the case of dogs and cats, most of us have a clear idea of what they can eat, when to give them water, how much exercise they need, and even how they will behave if they do not expend their energy. But when it comes to horses, some people think it is enough to treat them like a larger dog. The reality is very different.

In our first study, we compared the physical strengths and capacities of both species (5). In terms of strength, anyone who has seen a large dog knows it can pull with considerable force, even several times its own weight—but this is minor compared to what a horse can do.

Studies have calculated that horses weighing 300 kilograms can pull between 4,000 and 5,000 kilograms on smooth surfaces. In the case of criollo horses, which weigh approximately 450 kilograms, they can easily pull 900 kilograms, and larger breeds are capable of moving far more.

In the case of Mérida’s carriage horses, they weigh around 450 kilograms, and the carriage they pull weighs about 700 kilograms including passengers. Therefore, it can be inferred that the physical effort is minimal for an animal with such capabilities.

Physical Endurance

Endurance is another important difference. A well-trained dog may cover about 8 kilometers per day, and if it does not, it will likely release its energy by breaking things at home or barking excessively. In contrast, horses evolved to travel enormous distances—up to 80 kilometers per day in natural conditions.

Even when kept in enclosed pastures, measurements show they walk around 17 kilometers daily. Compared to this, 5-kilometer tourist routes through the streets of Mérida are relatively short.

Feeding and Water Management

Where the differences become truly critical is in feeding and water management. While a dog can drink or eat shortly after exercising, horses do not tolerate this kind of handling. Their digestive system functions very differently and is extremely sensitive.

Excess water, inappropriate temperature, or simply offering water too soon after work can trigger colic—one of the leading causes of death in horses. For this reason, the safest approach is to provide water in small amounts at intervals or to wait some time before feeding.

Final Reflections

In short, horses are not the same as pets like dogs. They are larger, stronger, with different endurance capacities and a much more sensitive digestive system. Pulling a carriage should not automatically be considered mistreatment, but rather evaluated based on the actual capabilities of horses.

Only with clear information about their capacities and needs can we make responsible decisions about how to treat them.

Read the second part here: The Misunderstood Carriage Horses of Mérida. Part II.

Editorial note: Image generated for illustrative purposes to provide context. It does not represent a specific horse or carriage evaluated in the cited studies.

 

References

Stronge et al. 2024. Resources Policy. https://doi.org/10.1016/j.resourpol.2023.104586

Decree No. 402. Official Gazette of the State Government. Latest amendment: July 5, 2021.

Mills et al. 2025. In Handbook on Animal-Assisted Therapy. https://doi.org/10.1016/B978-0-443-22346-4.15001-2

de Albuquerque et al. 2018. Journal of Equine Veterinary Science. https://doi.org/10.1016/j.jevs.2018.06.014

Tello Pasos et al. 2020a. Bioagrociencias. http://dx.doi.org/10.56369/BAC.3154