Assessing Risk of Injury from a Dog
Dangerousness does not necessarily equate with aggressiveness. A 50 kg enthusiastic excited dog running right into an owner and knocking down or injuring that person is dangerous. On the other hand, a growling dog that has never bitten is aggressive but not necessarily dangerous. Aggression has been defined as "behaviour that leads to the damage or destruction of a target entity." Some definitions of aggression also include the display of threats in the absence of injury. Thus aggression encompasses a wide variety of behaviours from subtle body postures and facial expressions to explosive attacks. Aggression can be an expression of normal or abnormal behaviour. Description of the behaviour sequence, context, frequency and severity of aggressive events as well as health status of the dog allows us to tease apart appropriate normal from inappropriate abnormal behaviours.
Behaviour is always a sequence. Observing the entire sequence is essential to determine if an animal is behaving normally or not. In the case of canine aggression, we could illustrate the sequence as initial warning, such as a growl (initiation), then a pause; then in some cases, a bite (action); and finally, immediate volitional release (end of sequence). Behaviour becomes "abnormal" or illness-related if some of the steps from the sequence are omitted or altered. A dog growling and biting simultaneously without any other form of warning has an altered sequence, because there is no clear initiation phase. Aggression can be the result of fear or anxiety. Anxiety is defined as anticipation of a future threat or danger (real or imaginary). Anxious dogs occasionally are unable to tell the difference between real threat and absence of threat. It is therefore important to realize that some aggressive dogs may in fact be ill and suffering from an anxiety disorder.
Appropriateness of the Aggressive Behaviour Given the Context
Context is also important to determine if behaviour is normal or illness-related. Behaviour can be inappropriate given the context. If I decide to randomly kick a person on the street given that this person did not even interact with me, kicking is inappropriate behaviour on my part in the described context. If, on the other hand, I am being mugged on the street and I am kicking my assailant, the same behaviour becomes appropriate. The context makes all the difference. A dog with an otitis bites the veterinarian (or owner). Context will be considered (painful condition, defensive aggression) when interpreting this aggressive event, and this dog will likely not be labelled as a high-risk dangerous dog. A dog will bark or growl briefly at the approach of a stranger and then he will wait and watch for the response. Based on the response of the receiver (the stranger in this example), the dog will decide on its subsequent action. The behaviours will depend on the receiver's response and the dog's interpretation of the response. If a dog growls, snarls and lunges systematically at everyone approaching without first warning (barking and/or growling) then pausing for a response, that aggressive behaviour becomes inappropriate and out of context. That dog is ill and is unable to make the distinction between threat and non-threat.
Severity and Frequency of the Aggression Given the Context
A dog can bark, growl, lift its lips, snarl, snap, bite, and then latch on or release. Bites can be single or multiple, inhibited or uninhibited. Clients are questioned on the severity and frequency of the aggressive events. Severity of bite can in some cases be exacerbated by fear or pain. The veterinarian must determine whether the severity and/or frequency of the aggressive behaviours are appropriate for that given context.
Predictability of the Aggressive Events
The context (triggers and specific situations) and the dog's body language are used in determining predictability of the aggressive events. If the dog exhibits only defensive aggression, the events are more predictable. Defensive aggression for the purpose of this presentation is defined as one individual "approaching or entering the animal's space" and interacting with the animal (touching, handling); the animal reacts aggressively to the approach or physical contact. Offensive aggression for the purpose of this presentation is defined as aggression occurring without interaction (touching, handling or even looking at the animal). The aggressive animal is the one approaching the individual (victim of aggression). The trigger for the aggressive behaviour is often difficult to identify.
Size of the Patient
A larger dog can potentially produce more damage.
Health Status of the Patient
A painful condition may exacerbate anxiety and aggression. Dogs that are behaving abnormally can be more unpredictable and therefore more dangerous.
Social Environment (Humans and Other Animals)
Relative risk for a young child unable to read and interpret canine body language can be increased, as the child will not understand a warning growl.
Any dog can be aggressive and bite. A zero-risk level of bite does not exist for a live animal. So the only way to guarantee that a dog will never bite again is to kill the dog. Assessing level of risk for a specific case requires a complete analysis: the animal, its behaviours and health status, and all interactions in its social environment. Clinical cases will be presented to illustrate various points.
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3. Overall KL. Clinical Behavioral Medicine for Small Animals. St. Louis, MO: Mosby; 2013.