What cluster does your dog reactive dog (DRD) fall into?

This is an owner-friendly screening tool, developed by clinical animal behaviourists, Dr Himara Van Haevermaet and Prof Daniel Mills at the University of Lincoln, which should help you appreciate your dog's likely reactive dog cluster type based on the frequency of nine key reactive behaviours, which have been shown in our research to represent different forms of the issue. It also provides some basic guiding principles on what this means for risk and where to focus training. Always prioritise risk management, then containment of the issue before attempting long term resolution.

Please note this tool does not replace professional behaviour assessment or advice, and we recommend consulting a veterinary behaviourist or clinical animal behaviourist before making management or training-related decisions.

The research

For the purposes of this app, a DRD is defined as ‘A dog showing one or more of the following behaviours towards another dog: barking, growling, snarling, lunging, snapping, nipping, biting, whining, or stiff posture with raised hackles and staring’.

Frustration behaviours include barking, lunging, and whining.
Posturing behaviours include snarling, growling, and adopting a stiff posture with raised hackles.
Oral attack behaviours include snapping, nipping, and biting.

DRDs have been found to group into 4 clusters reflecting different styles of responding, shaped by rearing environment, motivation, learning history, and thresholds for reactivity.
Knowing your dog's cluster can help you appreciate better the risk they might pose and their risk of escalation, as well as where to focus training to reduce the associated risk of harm.
Professional behavioural support is strongly recommended for dog reactive dogs, and especially those that fall into Clusters 3 or 4.

Understanding Your Dog's Cluster

All dog-reactive dogs, irrespective of cluster type should have risk management measures implemented. These include the following:

Maximise distance to prevent your dog from being able to make contact with other dogs. This may involve walking during quieter times of day or night, travelling to low-traffic areas, or hiring secure fields.
Block visual access to other dogs when necessary to reduce arousal.
Prepare clear emergency strategies for unexpected encounters on your planned walk (e.g., identifying space to move off paths). It may help to walk the route alone first to assess potential exit points.
Use a well-fitted harness and collar to maintain good control of your dog.
Avoid extendable leads; use fixed length leads for better handling and safety.
Use a double-ended lead with two attachment points so your dog remains secure if one point fails.
Fit a muzzle when walking in public if there is any risk of contact with other dogs. The muzzle should be introduced positively and allow panting, drinking, eating, and vomiting. Welfare-friendly muzzles and fitting advice can be found on The Muzzle Movement website
Walk only one dog at a time to ensure full control.
Ensure all handlers are familiar with and consistently follow these risk management measures.

General Guidance: In addition to standard risk management measures

Minimise opportunities for your dog to practice reactive behaviour, as repeated exposure can strengthen unwanted responses.
Avoid inadvertently reinforcing reactive behaviour through attention (positive or negative) immediately after a reaction. Instead, wait until the reaction has ended. If/when it is safe to do so, then ask your dog to perform a series of well-known behaviours that can be reinforced. Please note that if there is a risk of redirection then seek professional advice first.
While maximising distance should reduce the chance of reactions, if they do occur, vary the behaviours you ask for so your dog does not learn a predictable sequence (e.g., “I bark and lunge, then sit, give paw, look at handler, and get a treat”). This reduces the chance of the reactive behaviour from becoming part of a reinforced sequence.

Cluster 1: Low risk signallers

Profile: Moderate frustration and posturing, low risk of oral attack. These dogs tend to avoid escalation and may prefer avoidance.

Focus: Give them time to process the situation, without making it more intense. Teach and reinforce turning away and looking back towards owner in order to disengage. Reward avoidance behaviours to build confidence in safer responses. Ensure your dog has a secure attachment to you.

Cluster 2: Frustrated escalators

Profile: High frustration, moderate-to-high posturing, moderate risk of oral attack. Dogs in this group are more likely to escalate when arousal levels are high, this may be more likely if they are restrained e.g., on a lead.

Focus:Increase frustration tolerance; by ensuring they have an effective coping strategy. Work may include counterconditioning i.e. teaching an alternative response to other dogs and desensitisation i.e. gradual exposure to reduce arousal.

Cluster 3: Impulsive escalators

Profile: Moderate frustration, but high posturing and risk of oral attack. These dogs are more willing to make physical contact, even without high frustration. This may relate to traits such as impulsivity, poor risk assessment, or reinforcement history.

Focus: Reduce impulsivity and encourage healthy decision making to reduce the risk of putting themselves in a dangerous situation. Long-term work may include consistent reinforcement of self-control (appropriate uncued responses) and ultimately appropriate behaviours when seeing other dogs at a distance.

Cluster 4: Risky rapid escalators

Profile: Very high frustration, posturing, and risk of oral attack. These dogs escalate rapidly and represent the highest risk group.