Cimarrón Uruguayo

Pippa Elliott
Dr Pippa Elliott (BVMS MRCVS, University of Glasgow)
Photo of adult Cimarrón Uruguayo
Leonardo Botião Fonseca /

From the 2kg Chihuahua to the 90kg Great Dane, there is a huge variety of canine sizes, shapes, and temperaments. Each of these different dog breeds was created with a different purpose in mind. For the Cimarrón Uruguayo that purpose was to hunt and guard.

As a guard dog, the Cimarrón Uruguayo is about as far from a lap dog as it’s possible to get, whilst still remaining canine. They originated from fierce dogs of the Molosser type, imported into Uruguay by Portuguese colonisers.

In the modern day, the Cimarrón Uruguayo is an impressively strong dog with a tendency towards aggression. They are consummate guard dogs, so much so that the breed is the mascot of the National Army of Uruguay. Given the dogs’ strength and unpredictable character, they should be considered a working dog and are unsuited to life as a family pet.

About & History

Although the origins of the Cimarrón Uruguayo date back the 17th century, we know a surprising amount about the breed’s development. The Cimarrón’s ancestors where huge, battle hounds of the Molosser type. They accompanied Portuguese colonisers and European traders when they arrived in Uruguay, but were later abandoned or escaped. These dogs lived wild, inter-breeding at will, and became consummate hunters in order to survive.

In the 18th century, the fore-runners of the Cimarrón dog attacked livestock and sometimes people. This led to the government placing a bounty on their head, paying out for each dog killed.

However, the Cimarrón adapted to their new role as outlaw, and despite the odds, continued to survive. At which point it occurred to people that they’d make great guard dogs, and an effort was made to rehabilitate them. Thus began a period of partnership where the dogs’ skills were harnessed for constructive purposes, and their persecution stopped.


Cimarrón Uruguayo Large Photo
Andres de Montbard /

The Cimarrón Urguayo is the prize-fighter of the canine world. He’s large, muscular, and compact; all the better to throw his weight around in a fight. The Cimarrón has the general appearance of the large mastiff-type dogs (Molossers) dating back to ancient times, when they were used as fighting dogs by the Greeks.

However, their face is slightly narrower and more Labrador-like than heavy mastiff. They also have small drop ears, which are sometimes cropped in their native Uruguay, to make them look even more imposing.

This breed has a short, no nonsense coat with a dense undercoat, which is overlain by short, smooth guard hairs. The usual colour is brindle or pale yellow with a black mask.

Character & Temperament

When the breed standard requires the dog to have “great courage”, this hints at their character. Indeed, think back to the roots of the Cimarrón Uruguayo and this puts their temperament in context.

This is a breed that was abandoned by man and had to survive in the wilderness by hunting wildlife. Thus, those dogs that had a strong prey drive survived. With successive generations, this led to a dog that will predate on larger animals, and they are fully capable of bringing down deer-sized prey.

Thus, the Cimarrón Uruguayo regards family pets as potential prey. Even when socialised with other animals as a puppy, their instinct to hunt and kill is so strong that they are not to be trusted. Indeed, characteristic of the breed is a poor tolerance of other dogs, which sadly means dog-on-dog aggression is the rule rather than the exception.

On the plus side, remember the Cimarrón Uruguayo is a working dog. When used for their intended purpose of guarding they come into their own. They are superb guard dogs and woe betides anyone who intrudes as the breed is aggressive to strangers.

However, the Cimarrón Uruguayo does have a softer side. When raised by an experienced handler who is knowledgeable about the breed, they are extremely loyal and even considered calm and gentle by those people the dog knows and trusts.


The Cimarrón Uruguayo is a self-determined breed that likes to make their own decision and do their own thing. This, combined with a tendency to aggression, makes them a challenge to train. A fearful Cimarrón Uruguayo puppy will attack rather than withdraw, which means adequate socialisation as a youngster is essential. This creates a good foundation on which to train the adult dog.

This is not a breed for novice owners, and the handler needs to be experienced with demanding dogs. The breed responds best to firm but fair leadership, but will quickly exploit an inconsistent or weak handler. Given the breeds fearsome reputation, a handler not in control is a scenario to avoid. This does not mean the breed can’t be trained; just that it takes a special skill set to achieve it.


There are no studies of health problems specifically relating to the Cimarrón Urguayo. However, given their similar lineage and appearance to other closely-related breeds, it’s not unreasonable to compare their health. Known problems might include:


Hypothyroidism or underactive thyroid glands refer to an inadequate production of thyroid hormone. The latter drives the dog’s metabolism, and insufficient thyroid hormone makes the dog sluggish, lethargic, and lack lustre.

Symptoms include lack of energy, unexplained weight gain, thinning coat, and recurrent skin infections. The condition is easily diagnosed by a blood test. The treatment is simply a life-long oral supplement of thyroid hormone to bring levels back up to normal.

Gastric Torsion

In common with many large dogs with deep-chests, the Cimarrón Uruguayo is at risk of bloat (also known as gastric torsion and gastric dilation and volvulus or GDV). This is a life-threatening condition that requires immediate corrective surgery if the dog is to survive.

Gastric torsion occurs when the stomach flips over on itself, sealing gas within it. As the stomach contents continue to ferment, the trapped gas expands causing extreme stretching of the stomach. This causes a range of serious complications, such as shock, toxicity, organ failure, and cell death, which ultimately can lead to collapse and death.

Prevention is key. This includes simple things, such as not exercising the dog for at least 90-minutes after a meal, feeding a high quality food that is low in fermentable ingredients and using strategies that prevent the dog eating too quickly.


A normal male dog has two testicles, both of which are descended into the scrotum outside the body cavity. Cryptorchidism is a condition whereby one or both testicles do not follow the expected path and are retained in the body or groin.

Retained testicles carry a greater risk of becoming cancerous and also of twisting on their blood supply. The latter causes strangulation of the testicle, with the dog becoming quite ill, very quickly.

If the testicles have not descended by the time the dog is a young adult, then desexing is advisable in order to prevent complications.


As a working dog, the Cimarrón Uruguayo has a metabolism that is geared to being active all day. However, if the dog doesn’t get enough exercise or is overfed, they are prone to gain weight.

An obese dog has a shortened life expectancy and is at greater risk of health problems, such as diabetes mellitus, arthritis, and heart and lung disease.

Hip / Elbow Dysplasia

Dysplasia refers to the malformation or poor anatomy of the hip and elbow joints. Since these joints are constantly in motion, when they are a poor fit this causes inflammation and pain. Depending on the severity of the problem, this may make the dog prone to early arthritis.

This condition is managed using a combination of pain relief, physiotherapy, weight management, and surgery.

Exercise and Activity Levels

The Cimmaron Uruguayo is a working dog and needs the physical activity and mental stimulation of having a job of work to do. This breed needs one hour of active exercise twice a day as a basic requirement.

Be aware that if left out in a yard as his primary means of exercise, the Cimmaron will set about guarding that yard. This could be place people, such as the mailman or visitors, at risk.


The Cimmaron Uruguayo has an easy coat to care for, but not necessarily a compliant character to go along with. So, whilst weekly brushing is sufficient to keep the coat in good order, it’s essential to get the puppy used to being groomed from a young age. A non-compliant adult dog is not something the owner wants to wrestle with.

In addition, it’s best to train the dog from an early age, to accept having their nails clipped and ears checked. Thus, if they have a health problem, they aren’t so much of a hazard to veterinary staff.

Famous Cimarrón Uruguayos

Enthusiasts of the breed should check out Pinterest and Instagram for photos of the breed.


The Cimarrón Uruguayo was originally a type of cross-breed, albeit one with roots going back centuries. Although a physically attractive dog, their temperament is not suited to that of a domestic pet, and therefore, deliberate hybrid mating are rare or non-existent.

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