Sudden Onset Aggression/ Rage Syndrome by Jim Gillies BSc A.Dip CBM

Rage syndrome is known by several names. Due to that lack of specificity about its origin it can be classified alongside idiopathic aggression as there seems to be a lack of apparent cause for the aggression. It is a syndrome that is inadequately understood, with many concluding a significant genetic component to the disorder. Others have attributed neurological disorders to account for the sudden onset of aggression of this type.  Symptoms include sudden, unprovoked, unpredictable and uncontrollable violent aggression towards another animal, person or object.

The behaviour is often attributed to Cocker Spaniels, with approximately 8% suffering from the condition. Although there are numerous examples of other breeds developing sudden onset of aggression for apparent reason. From a functional analysis perspective this is extremely difficult to diagnose. We ultimately cannot see the world through the eyes of a dog, therefore making it impossible to know for certain. Diagnosis to date has been predicated on purely behavioural signs, this of course has a margin for error and can be misinterpreted.

In an attempt to provide a diagnosis to any owner where rage syndrome is the suspected condition, a full medical, behavioural and neurological examination is required. Other illness may also cause aggressive outburst including brain tumours, head trauma and metabolic disorders such as low blood sugar. There are links between epilepsy and schizophrenia with the sudden onset of aggression. Partial complex seizures result from abnormal electrical activity in the temporal lobe of the brain, an area which oversees memory, sensation, and emotions. Seizures in this area can affect behaviour, specifically defensive and predatory responses, causing aggressive and threatening behaviour.

Some of the signs a dog may have rage syndrome include:

·         Behavioural changes

·         Depression Violent and uncontrolled aggression

·         Lunging toward targets

·         Growling

·         Snarling

·         Barking

·         Biting and snapping

·         Baring teeth

·         Curling lips

Providing a diagnosis for Rage Syndrome is particularly challenging. There may not be specific triggers for the aggression making it difficult to treat through standard counter conditioning and/or systemic desensitisation protocols. For some cases using pharmacology may be the best solution anticonvulsant medication, such as phenobarbital has been shown to have positive effects Dodman et al (1992).

Any diagnosis should be predicated by a full medical examination by a veterinary professional. It is more likely of medical origin rather than behavioural. Similar to idiopathic aggression there is likely some underlying cause exists, therefore establishing that cause will be essential to any treatment program (Doglistener, 2018).

The term rage syndrome is attributed to Dr. Roger A. Mugford. Dr Mudford is an Animal Behaviourist who found that rage syndrome can be seen in dogs around 7.5 months. Recent research discovered that it can present itself at around 3 months and as late as 2 years. Dogs were shown to exhibit the syndrome in one of the five critical learning periods identified in dogs. These critical learning periods occur at six weeks old, 12 weeks old, 24 weeks or six months, one year old and two years old.

In an attempt  to treat Rage Syndrome there are a variety of approaches. Antiepileptic drugs have been reported to be effective Dodman et al (1992). Behaviour modification can be ineffective as the aggression presents itself without apparent environmental triggers. Euthanasia for dogs that do not respond may be the only solution due to the risk the animal poses.


Dodman; Miczek, K. A.; Knowles, K.; Thalhammer, J. G.; Shuster, L. (1992). "Phenobarbital-responsive episodic dyscontrol (rage) in dogs". Journal of the American Veterinary Medical Association 201 (10): 1580–1583.