Behavioral problems

Why Are Chihuahuas So Aggressive?

Eduarda Piamore
By Eduarda Piamore, Expert in canine and feline psychology, education and training.. November 27, 2023
Why Are Chihuahuas So Aggressive?

Animal file: Chihuahua

Various studies have suggested that Chihuahuas show more aggressive traits that other dogs more commonly associated with aggression, such as the Pitbull. Despite these apparent aggressive tendencies, they are not considered potentially dangerous dogs, a categorization which can have legal repercussions in many countries. This is likely due to their small size. Being the smallest dog breed, they have much less potential for physical harm than a muscular dog such as the Pitbull. Unfortunately, it is likely their size which leads to many guardians ignoring their aggressive tendencies and neglecting their responsibility of care for doing so.

At AnimalWised, we know that breed is not the most important factor in dog aggression. While it can be of importance in learning how to care for a dog, we explain the real reasons why are Chihuahuas so aggressive?

You may also be interested in: Are Dobermans Aggressive Dogs?
  1. Reasons why Chihuahuas are aggressive
  2. Reasons why Chihuahuas are aggressive
  3. How to calm an aggressive Chihuahua
  4. How to treat an aggressive Chihuahua
  5. How to prevent a Chihuahua from becoming aggressive?

Reasons why Chihuahuas are aggressive

Aggression in dogs is a complex behavioral problem that occurs for various underlying reasons. This has led there to being different types of aggression recognized in dogs. Sometimes this aggression can be generalized, but there are different types because there are so many interrelated factors which would lead any dog to express themselves aggressively.

We are asking in this article why Chihuahuas are aggressive, but it is important to know these reasons can apply to any breed. Although we explain the specifics of Chihuahua aggression, every dog needs to be looked at as an individual. If we simply blame breed for a dog's behavior, we will never understand why aggression manifests in dogs, nor how to prevent aggressive behaviors.

With this context in mind, we can look at the reasons why Chihuahua are often aggressive.

Genetic heritage

It is impossible to deny that there is a genetic component that can favor the manifestation of aggressive behaviors in our dogs. A company called Dognition uses apps and training to investigate dog intelligence. They created a study which suggests that Chihuahuas have much higher aggression levels than other dogs such as the American Pit Bull Terrier[1].

While this study has been criticized for being based exclusively on the self-reporting of guardians who care for each breed, other studies have presented similar claims. This is the case with conclusions published by the American Society for Temperament Testing[2].

Through a series of behavioral tests, this organization observed that the American Pit Bull Terrier was positioned among the most tolerant breeds. They reached the astonishing figure of 87.6% in the positive temperament test, with the related the American Staffordshire Terrier following very closely with 85.7%. Meanwhile, Chihuahua dogs recorded a tolerance score of only 68.8% , according to the same parameters.

It is very important to note that these statistics do not exist in a vacuum. They present helpful data, but they are not conclusive about the reasons why certain dogs are seen as more or less tolerant. Factors such as education, experience and care received are much stronger determinents in how a dog will behave. This leads us to the following reasons why Chihuahuas are aggressive.


This point is directly related to the previous. Aggression is a resource that a dog resorts to when it needs to feel safe in difficult contexts. When a dog is afraid, it is because they perceive certain stimuli as threatening, even if this is far from the case in actuality. This threat pertains to their physical or emotional integrity, as well as for the well-being of the individuals they consider family.

The relationship between fear and genetic inheritance is a complicated one. It has been observed that some dog breeds are also naturally more fearful than others. This predisposition towards fear usually varies due to the different factors of non-social fear in dogs, such as heights, loud noises and fear of strangers or the unknown. In this sense, size and body composition seem to play a key role in the dog's response to fear, since types of small dog breeds usually show a greater predisposition towards fear than large dogs.

It is no coincidence that Chihuahuas are both among the most fearful dogs and among the dog breeds with the greatest predisposition to aggression. They are known for a high predisposition to fear of heights and surfaces, something that is probably related to their small size and low muscle density. On the contrary, they are brave when it comes to defending what they consider valuable resources for them, as we will see below.

Reasons why Chihuahuas are aggressive

Resource protection

All dogs have a natural need to protect the resources they consider key to their survival and well-being. When they feel the need to resort to aggression to protect their resources, many guardians see the dog as being possessive of resources.

When we discuss ‘resources’, we are not only referring to material goods such as food, toys or even their territory, but also to immaterial resources. The attention, care and well-being of their guardians are common examples of such immaterial resources. This can be manifested in a dog barking or even attacking anyone who approaches their owner because they think they will take away this resource, regardless of actual intention.

Likewise, the protection of resources can also manifest itself towards the guardians themselves. For example, if your Chihuahua won't let you near them while they are eating or if they growl at you when you try to take a toy out of his mouth. We look at some specific reasons for the former with our article on causes of food aggression in dogs.

Problems in socialization

This is probably the main cause that explains why Chihuahuas are aggressive. It is also closely related to the previous reasons. Socialization of adults dogs and puppies is a process that allows dogs to assimilate a variety of stimuli in their environment. They learn boundaries and healthy interactions with others, diffusing fear and building confidence as they do so. With successful socialization, they should learn that aggression is an extreme resource only to be used as a last resort.

A dog that has not been properly socialized becomes more prone to fear. They have more difficulty communicating with other dogs and interacting peacefully with other individuals. All these reasons reaffirm the importance of socializing your Chihuahua from an early age. The most vital socialization period in dogs is between the ages of three weeks and three months of life since this impressionable time will help set the standard of behavior.

Another key factor for the stability of a dog's behavior is living with their mother and siblings during the first weeks of its life. During this period, the puppies' first and most fundamental learning occurs. The mother is responsible for teaching her pups the fundamental codes of their communication and social behavior. For this reason, puppies that are separated prematurely from their mothers and siblings tend to have more learning and interaction difficulties in adult life, as well as a greater predisposition to complex behavioral problems, such as aggression.

Stress and redirected aggression

When a dog is under a significant amount of stress, tension accumulates over time and can be released in aggressive behaviors. This aggressive response can manifest itself towards a person or other animal, even if they are not the source of the stress. It is for this reason we can describe it as redirected aggression, one of the many symptoms of stress in dogs.

Fear can also act as a driver for redirected aggression. This usually occurs in any dog that has been systematically exposed to situations that cause great fear. Practically any individual or stimulus that can cause a disturbance in their environment can activate an aggressive reaction to protect themselves, even if this individual has nothing to do with previous situations the dog has experienced.

It should be remembered that systematic exposure to fear has harmful repercussions on the behavior and mental health of dogs. One of them is to reduce their confidence until it makes the dog insecure. In more acute cases, it can lead to general panic when faced with other individuals.

Health problems

Beyond stress, there are many diseases and metabolic disorders that can alter a dog's behavior. They can increase their sensitivity and, consequently, the tendency to resort to aggression to protect themselves in a context where they feel particularly vulnerable. A significant factor is the dog not understanding why they are feeling unwell and their well-being is under threat.

Something similar usually happens with elderly dogs. They are often more prone to numerous health and behavioral problems, both because their senses are progressively deteriorated and because their immune system is increasingly weaker. This is why there are often health problems which are particularly common in older dogs.

Why Are Chihuahuas So Aggressive? - Reasons why Chihuahuas are aggressive

Maternal aggression

If you share your home with a pregnant or recently given birth Chihuahua, it is very possible that this aggressive behavior is associated with the need to protect herself and her puppies. Remember that dogs need specific types of care to have a healthy pregnancy and a safe birth. An essential part of this care is to respect their space and be very careful when handling her puppies.

Aggression associated with sexual behaviors

If you have two or more Chihuahua dogs, they will manifest a serious of behaviors once they reach the age of sexual maturity. This is because their hormone production will lead to a natural desire to copulate and reproduce. This can occur even with sibling dogs if you have two Chihuahuas of different sex. If you have two males, we will often see them become aggressive since they see each other as reproductive rivals. This intensifies when there are females in heat present.

These sexual behaviors include mounting, escapism and marking. We can even see male dogs try to mount other males. It is also common to observe aggressive behaviors related to competition for resources present in the environment, including sexually receptive partners. Furthermore, intersexual aggression is strongly related to dominance towards members of the same sex, although it can also be directed towards the opposite sex less frequently.

It is important not to confuse dominance with aggression in dogs. While the former manifests itself naturally in interactions between dogs and has to do with the hierarchical order of their species, the latter is a behavioral problem.

How to calm an aggressive Chihuahua

Treating Chihuahua aggression is a complex process which depends on the individual and their specific reasons for aggressive behaviors. Before we look at the various ways this problem is addressed in dogs, we can take a look at some practical ways to help calm a Chihuahua when they are experiencing an aggressive episode.

In order to create a protocol for dealing with Chihuahua aggression, we are going to look at two circumstances in which a guardian's actions can be decisive. The first is when the dog is aggressive to other people or animals outside of the family. The second is when this aggression is directed towards people outside of their family.

What to do if my Chihuahua is aggressive towards other dogs and/or people?

If you perceive that your Chihuahua is showing signs of discomfort, stress or outright aggression towards another dog or person, the best thing you can do is move away from the individual or stimulus that produces this negative reaction. You can attract their attention to something they enjoy as a form of positive redirection. This can be a treat, a toy or an activity, the latter including going for a walk, playing with a ball or tracking games.

Unfortunately, a Chihuahua's aggression can become physical. It is possible your dog will try to bite another dog or otherwise try to attack them. While the Chihuahua is a small dog, they can cause damage and even a small bite can become infected. If your dog is not yet responding to training and is a bite risk, you should muzzle them when taking them for a walk. Get them used to the muzzle with positive reinforcement.

What do I do if my Chihuahua is aggressive towards me?

If your Chihuahua is aggressive towards you, it is best to walk away and leave them alone. Leave them in a space where they feel safe until they can calm down. It is normal to wonder why a dog is suddenly aggressive towards you, but it is important to first respond to the situation at hand. Reduce their stress levels and help engender a calm environment.

Once you have given the Chihuahua space and they are able to calm down, you can try further interaction. At this point, you will be able to provide the education and training which can helps to avoid aggression in Chihuahuas. We explain this training in the section below.

How to treat an aggressive Chihuahua

Once the critical moment has passed and having managed to calm an aggressive Chihuahua, it will be important to understand why these aggressive responses occur. Understanding the reasons why a Chihuahua is aggressive is imperative in stopping this behavior. If we do not do this, we will not treat the underlying problem and the aggression will return.

It is important to know that any dog may reasonably become aggressive in certain situations. If the dog is genuinely under threat or they have a good reason to offer protection for their guardian, then we do not need to treat it as problematic aggression.

When we talk about how to treat aggression in Chihuahuas, we are specifically referring to a dog that shows a pattern of aggressive behavior, or that resorts to aggression to deal with a series of daily situations that make them feel uncomfortable when they should not do so. We do not treat specific reactions compatible with their context, but a behavioral problem that manifests itself through recurrent or permanent aggression.

If your Chihuahua has become aggressive, whether towards you, other people or other animals, the first thing you should do is seek the guidance of a veterinarian. Since a health problem can be a potential reason for your dog's aggressive behavior, this first needs to be ruled out. If a health problem is the underlying cause, treatment or symptom management should alleviate the aggressive behaviors.

When physical illness is not the source of the aggression, we will need to look to behavioral treatment. This is best carried out with a dog trainer or someone with expertise in canine ethology. They will help to interpret your dog's symptoms, look at their individual context and determine the root of their aggression. Based on this information, we can set up a series of guidelines according to their specific needs and characteristics.

One of the greatest reasons why we see aggression in Chihuahuas is that many guardians do not recognize the importance of training this animal. Since they are toy-sized dogs, too many people treat them as a toy and do not establish the training, education and boundaries that all dogs need for a harmonious life with humans. We show you some of the practical implications of this in the section below.

Learn more with our article on training and education of a Chihuahua.

How to prevent a Chihuahua from becoming aggressive?

If your Chihuahua has already started to display aggressive behavior, you will need to address the reasons explained in this article. For those who have recently adopted a Chihuahua or are thinking of doing so, we must stress the importance of training and education. Without these aspects of their care, fear, aggression and other unwanted traits are most likely to develop.

We can best prevent aggressive behavior in Chihuahuas with the following safeguards:

  • Wait until the weaning period is complete before separating the puppies from their mother. This means a minimum of 8 weeks of life, although it can be as much as 12 before the mother will reject her puppies naturally.

  • Socialize the puppies correctly with other dogs and people. If you have adopted an adult dog, then socialization can be more difficult, but it is no less important.

  • Provide adequate preventive medicine throughout their life, which must include a vaccination schedule, internal and external deworming, a complete diet compatible with the nutritional requirements of each stage of life and preventive consultations with the veterinarian. The latter should be carried out at least once a year, increasing to two years of age once they become senior dogs. Due to the low muscle density of Chihuahuas, it is also key to protect them from the cold, since they are very sensitive to low temperatures and can shiver very frequently. Learn more with our article on the most common Chihuahua health issues.

  • Respect the basic freedoms of animal welfare and allow our dog to express their nature free of fear.

  • Teach our dog which behaviors are appropriate and which are not, using the most appropriate and safe methods for this purpose. Avoid punishments and misuse of scolding, since they tend to produce fear and stress. This favors the manifestation of aggressive behaviors and other problems, rather than avoids them. We always encourage the use of positive reinforcement in dog education to help in the assimilation of good behaviors and stimulate their learning capacity.

Last but not least, don't forget to spend time building a positive bond with your Chihuahua. This is one that is based on trust and mutual appreciation. Doing so will help to ensure training and education can be carried out smoothly and they avoid insecurity which leads to aggression.

If you want to read similar articles to Why Are Chihuahuas So Aggressive?, we recommend you visit our Behavioral problems category.


1. Hare, B., & Woods, V. (2016). Pit Bulls Are Chiller Than Chihuahuas. The Atlantic. Retrieved from:

2. American Temperament Test Society. (2023). ATTS Breeds Statistics. Retrieved from:

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Why Are Chihuahuas So Aggressive?