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What is Fear Aggression?

Fear related aggression can be a difficult and dangerous problem and typically takes time and patience to reverse. Some dogs, such as toy breeds and shepherding breeds, are more likely to develop fear responses, and sometimes aggression.

Although many fear related problems may be eased through the application of proper exercise, diet, and training, some dogs may need additional help such as antianxiety or antidepressant medications to control their actions and reach their full potential. 

Aggression related to fear can be a difficult behavioral trait to change and should be handled carefully. This is an easier disorder to prevent than to treat.

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Symptoms of Fear Aggression in Dogs

Dogs that are experiencing fear around people may express it in several ways. Behaviors that may be exhibited when a dog is afraid may include:

  • Aggressive chewing
  • Biting
  • Cowering
  • Ears held back
  • Escape behaviors
  • Exaggerated yawning
  • Excessive vocalizations
  • Holding head lower than back
  • Licking nose or face (with no food present)
  • Lip tension
  • Nipping
  • Pacing
  • Panting
  • “Punching” with the muzzle
  • Showing the whites of the eye
  • Tail tucked under
  • Timidity
  • Trembling
  • Whites of the eye turning pink or red


In some cases, aggression issues due to fear can become unmanageable with behavior modification and training methods alone. Chronic fear and aggression may require psychiatric medications to assist in treatment. Most psychiatric medications require six to eight weeks before substantial improvement is seen, although a few are relatively fast acting. The most commonly used psychiatric medications for canines include: 

Benzodiazepine Derivatives

This category of drugs includes medications such as Valium and Xanax, which are frequently effective for the temporary relief of anxiety and fear as these medications have a relatively quick action. Unfortunately, dogs often build up an immunity to the  compounds used for these treatments making them less suitable for long term usage.

Selective Serotonin Reuptake Inhibitors

Often used in canines for generalized fears and obsessive-compulsive behaviors, this category of medication includes Fluoxetine, Prozac, and Zoloft. SSRIs are one of the most frequently prescribed medication for anxiety disorders, and Fluoxetine is one of the more successful treatment methods for aggression issues. 

Tricyclic Anti-anxiety Medications

Medications such as Clomicalm and Elavil fall into this category, and are commonly used to treat both anxious and obsessive behavior in canines but may cause troubling side-effects, particularly when weaning the patient off of the drug.

Causes of Fear Aggression in Dogs

Triggers that may cause fear and aggression in dogs are typically a combination of nature and nurture. Possible components to developing aggression due to fear could include: 

  • Developmental Factors - Circumstances such as abuse, traumatic events, or loss of a caretaker may have more of an effect when they occur during a puppy’s developmental phase and improper socialization early in life can cause a dog to be more fearful
  • Environmental Factors - Being in an environment of restriction and overcrowding such as a shelter or puppy mill may induce chronic fear in dogs that may lead to aggression; violent environments or incidents may trigger fear in canines, and in some situations may lead to the development of anxiety disorders or PTSD 
  • Genetic Predisposition - Certain dogs or breeds of dog may have a slight predisposition to develop aggression due to fear; some shepherding and toy breeds may have an inherited predisposition for fear 
  • Physical Disorders - Some physical disorders, particularly those that cause chronic pain, can elicit aggressive behavior in canines due to fear; other disorders with a physical basis that may lead to fear-based aggression may include bacterial or viral infections or the loss of senses such as hearing or sight

Diagnosis of Fear Aggression in Dogs

Your veterinarian will collect information for a behavioral history when you visit the clinic for a behavioral problem such as aggression. Data that is requested to complete a complete behavioral history would typically include the patient’s sex and age as well as anything else that may be known about the breed of the canine. Information about the circumstances prior to any episodes of aggression as well as how your dog’s behavior changed after the incident can also prove helpful in diagnosing any underlying disorders. 

Facts regarding any changes to diet or any new medications that have been introduced recently will also be needed as well as which corrective methods have already been tried and the result. If your veterinarian suspects a medical component to the behavior at all they will typically perform a complete physical examination as well, which will include standard diagnostic tests such as a complete blood count, biochemistry profile, and urinalysis.

Treatment of Fear Aggression in Dogs

Treatment for behavior issues will depend on both the severity and the underlying trigger for the behavior. Chronic aggression due to fear can be a potentially dangerous situation and should be addressed by a veterinary professional. Treatment for dogs who have shown fear related aggression should be a cooperative effort between the animal’s owners and a professional trainer or behaviorist. It is important not to scold or punish the fearful dog for its fear response. Scolding your dog for fearful behavior may actually enforce their feelings and increase the chances that fearful behavior will turn into aggressive behavior. 

One of the training methods that is commonly utilized to treat fear disorders is known as desensitization, a method in which treats and praise are used in conjunction with the presence of the object of fear to cause the feared object to become more a more positive and familiar presence and thereby reduce the fear of it. Regular obedience training may also be effective in mitigating fear and anxiety, reducing the likelihood of an aggressive response, and may be utilized to distract the dog from negative stimuli in a technique known as a counter-conditioning treatment. In some cases, behavioral therapy and training are not enough to calm the patient and anti-anxiety or anti-depressant medications, such as diazepam or Prozac, may be employed to calm your companion.

Recovery of Fear Aggression in Dogs

Medications given for psychological imbalances will take several weeks before their effectiveness is known, and it is essential that your veterinarian knows all of the other medications your dog is on. The way that canines metabolize this drug is very different from the way that a human metabolizes the drug and dosages will vary based on your dog’s specific response to the medication. 

Many anti-depressants and anti-anxiety medications have contraindications with certain pain medications, antihistamines, and even herbal treatments such as St. John’s Wort or Kava Kava. Medications alone are rarely effective in eliminating challenging problem behaviors, and changes to both your pet’s exercise levels and diet are often helpful in reducing problems. Continuing behavioral training will help your pet to become a happier and healthier individual.

Fear Aggression Questions and Advice from Veterinary Professionals

Mini Schnauzer Chin
10 Months
Moderate condition
0 found helpful
Moderate condition

Has Symptoms

Pulling and barking
Pulling and barking at approaching

We have a 10 month old minii schnauzer..had him since 8 weeks old. FRom the beginning has always been a puller on leash and always barks insistently at people and other dogs that pass by or he sees at a distance. But today he did something new..a child was going over to pet him and he lunged at her .didn't get 5 feet away..and then ran in the opposite direction. Like he was afraid of her. He was on a leash,,,up until this point ,once he'd go over to the dog or person and be friendly and get to know them. Loud noises do scare him..HELP!!! He is no fun to walk at all..

Dr. Michele King, DVM
Dr. Michele King, DVM
502 Recommendations
Thank you for your email. Schnauzers are terriers and, by nature, are curious, and protective. They can get a little bossy, and a little nippy at times. Thankfully, Kermie is very young, and very trainable. The best thing to do for her would be to enroll her in puppy classes, as they will be able to help teach her some manners. If you get through the basic puppy classes and the trainer feels that she needs further work, they can either help you with that, or refer you to a more advanced trainer. Your veterinarian can help you find a good puppy class near you. Schnauzers can be such fun dogs, I hope that you are able to curb these behaviors quickly!

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Staffordshire Bullerrier Cross.
Seven Years
Serious condition
0 found helpful
Serious condition

Has Symptoms


My seven and a half,male,unneutered Staffordshire Bull terrier cross has fear aggression I think,we had him since he was ten months old, all I know he was chained up outside and fed scraps, he doesn't like shouting as he bites,my stepson has been staying with me and his dad for two weeks, well Billy had 5 fits,which the dog doesn't like,when Billy came round he was disoriented and when Cole, the dog,jumped up him, Billy was get him off me,so of course Cole was trying to bite him,which he did before I put him in the back room,he goes mad barking and scratching for about maybe ten ,five teen minutes,then whines like a baby,this happened yesterday and then it happened again,he has already nipped me and bit my partner on the leg quite badly before.I have phoned my local pdsa up and they want me to muzzle Cole, I have tried, he moves his head away, so I'm not going to force him,I've tried leaving the muzzle on the floor,he doesn't go near it,they have told me because he is a biter the vet wont see him unless he is muzzled,I had a bahaviourist round and explained he said its not fear aggression, i know it is,by what i have read what others have said,all they tell me that the best thing is to pts,as this has been going on now for over two years off and on,and it will only get worse,which it is.afterwards its as though cole has done nothing wrong,he loves people when we are out,just not other dogs,I've got family with young children and older children that won't pop round because of the dog,I have a dog gate, he will jump over it,also if I use the vacuum he will actually bite it,he gets anxious if I go in my loft by using stepladders, he whines like a baby,I think as he has got older,he has had more problems and I think that if I do keep him till he is older,then I am going to have even more problems with him,he doesn't like the bath or being picked up,that's also a no no.I am seriously thinking of pts,but as I say it'should trying to muzzle him.

Dr. Callum Turner, DVM
Dr. Callum Turner, DVM
2001 Recommendations
These issues are never straightforward and the approach for one dog may for different for another, if the Behaviourist believes it is not fear aggression it may be just a lapse in training and allowing him to always get his own way. Cole should have been neutered at a young age which may have helped some aggression issues; if Cole is attacking people like your Stepson and you are unable to control him you should consider either residential training or euthanasia. Regards Dr Callum Turner DVM

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Jack Russell Terrier
6 Months
Serious condition
0 found helpful
Serious condition

I have just discovered that my puppy may have come from a puppy farm and is showing signs of fear aggression, She was 10/12 weeks old when i got her and was told that she had been bought as a family pet but had to re-sell her due to a family member having allergies, i have since found out that the same people have been selling other puppies and using the same con line. Once i had her jabs done i had her straight out meeting other dogs and she always acted very timid around them and i put this down to her size, she is a Jack Russell. She was fine with my 2 cats and also my Grandkids, but she has gradually has been showing signs of fear aggression which seems to get worse every time i take her out, i have tried the distraction method and it can work as long as she is not approached by another dog or person, she has a snarl at the family if any of us go to move her physically and has now went from puppy play with the cats to a sort of head butting, herding type of movement. I really believe that if i am right and she has come from a puppy farm that she has not had the socialisation most needed in puppies. Would getting her involved a training class correct this behavior or will it be too stressful on her. My biggest fear is that she will go into attack mode on my grandaughter who is 15 months old.

Dr. Callum Turner, DVM
Dr. Callum Turner, DVM
2001 Recommendations
I understand your concerns and the puppy trade is a disgusting one which I’ve witnessed first hand as a Government Veterinarian and there is an interesting BBC Panorama (like 60 Minutes or 20-20 but from the UK) about the underhanded tactics and deceit in this industry which is appalling. Aggression may occur for various reasons and this behaviour needs to be addressed quickly as the longer it is left, the more difficult it will be to correct; puppy training classes can be useful but risky, it would be best having a one on one with a Trainer and using their dogs to help correct this behaviour in Millie. There are general tips about punishing this behaviour and pinning a dog on the ground to show dominance but if you can speak with a trainer to get specific tips for Millie a quicker resolution can be found. Regards Dr Callum Turner DVM

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Cattle Collie Dog
2 1/2
Critical condition
0 found helpful
Critical condition

My dog definitely has an inherited predisposition to fear - she is a border collie/aussie cattle dog mix - I've had her since 8 weeks and she was socialized early - did puppy class, regular obedience training, agility etc- she is highly intelligent and well trained, but has aggression that seems fear based - she remains terrified of everything, regardless of many hours a week of counter conditioning/desensitization - I have consulted trainers, behaviorists, done 40 days of boot camp and daily training and nothing is alleviating her fear. Tried cannabis oil, prozac and anxiety vest - nothing works at all. Do you recommend trying valium, or can you advise me at all? I worry about her biting my 4 year old - she has bitten me, and recently had knee surgery that is only making her issues way worse. I'm the last person to even consider giving up on a rescue dog, but I have put countless hours a week into her training for 2 1/2 years with no resolution and spent $12, 000 on various attempts at solving this problem, and I am seriously considering rehoming her, as much as it breaks my heart.

Dr. Callum Turner, DVM
Dr. Callum Turner, DVM
2001 Recommendations
When I hear an owner ask about Valium (diazepam) or similar medications, it is usually because they don’t have the patience to train a dog properly which you obviously have dedicated time and resources to; the use of benzodiazepines is not a real solution for day to day life and should only really be considered for short term therapy. There are some medicines for noise aversion but general aggression is a bit more difficult to treat; I cannot recommend any particular medication in a dog I haven’t examined but would advise you speak with a Veterinary School to see if they can offer any assistance. Regards Dr Callum Turner DVM

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