There is a common misconception that once a dog bites a human, they get an irresistible “taste for blood.” While it’s true that dog with a bite history may be more likely to bite again in the future, it has nothing to do with enjoying the taste of blood or flesh.
In this article:
1. Why dogs bite
2. Biting works
3. Bite inhibition
4. Prognosis for dogs that bite
5. Dogs in rescue
6. Preventing bites
Why dogs bite
In most cases, dogs bite people as a distance increasing behavior. The dog feels scared, frustrated, or threatened, and they want whatever is making them uncomfortable to go away.
All dogs have the ability to bite. Whether or not they do so depends on a ton of variables (in no particular order):
- socialization history
- physical health, including chronic and acute pain
- mental health, including anxiety
- the dog's level of trust and communication with their human
- the environment
- familial genetics
- and so much more
Bites to humans are very rarely related to prey drive or ”having fun.” Behaviors such as barrier reactivity (for example, chasing someone as they walk along the other side of a fence), may be mistaken for prey drive, but are actually associated with resource guarding or fear.
Biting works
Most dogs bite as a last resort, presenting a series of behaviors prior to biting in an effort to increase distance. Some of these behaviors are subtle, such as lip licking, excessive yawning, or avoiding eye contact. Others are more obvious, such as moving away, cowering, or growling. If these behaviors are not successful in achieving distance, the dog may escalate to biting. If biting is successful in achieving distance while the other behaviors are not, the dog may escalate to biting much faster in similar situations in the future.
Bite inhibition
The strength at which a dog bites will vary between individual dogs, even of the same breed, because dogs often do not bite at their full physical potential. This is referred to as “bite inhibition.” While dogs can be taught bite inhibition in situations such as play or taking a treat, this has little to no impact on the strength of the dog’s bite when the dog is seeking distance.
The only accurate measure of a dog’s bite inhibition is past bites. A dog who presents bite inhibition in play or when taking food will not necessarily present that inhibition when scared, frustrated, or threatened. We can expect all future bites to be at the same or greater strength as past bites, even with management and behavior modification.
Ian Dunbar's Bite Scale
One of the most widely used resources by veterinary and behavior professionals for evaluating the severity of a dog bite is Ian Dunbar's Bite Scale. While it isn't perfect and should always be used in combination with other evaluation factors, it can be a good starting point for understanding a dog's prognosis.
- Level 1. Obnoxious or aggressive behavior but no skin-contact by teeth.
- Level 2. Skin-contact by teeth but no skin-puncture. However, may be skin nicks (less than one tenth of an inch deep) and slight bleeding caused by forward or lateral movement of teeth against skin, but no vertical punctures.
- Level 3. One to four punctures from a single bite with no puncture deeper than half the length of the dog’s canine teeth. Maybe lacerations in a single direction, caused by victim pulling hand away, owner pulling dog away, or gravity (little dog jumps, bites and drops to floor).
- Level 4. One to four punctures from a single bite with at least one puncture deeper than half the length of the dog’s canine teeth. May also have deep bruising around the wound (dog held on for N seconds and bore down) or lacerations in both directions (dog held on and shook its head from side to side).
- Level 5. Multiple-bite incident with at least two Level 4 bites or multiple-attack incident with at least one Level 4 bite in each.
- Level 6. Victim dead.
Prognosis for dogs that bite
Whether or not a dog can safely and reasonably live in a home is best determined by a qualified behaviorist. In general, consideration should be given to the following factors:
- the severity of the dog’s bite
- what warning behaviors, if any, the dog presented before biting
- how likely the dog is to be in a similar situation in the future
- the dog’s physical and mental health
- the ability and willingness of the humans in the dog’s life to adhere to management and behavior modification.
It is important to remember that management alone is not enough to prevent a severe bite incident, as management will almost always fail at some point.
Dogs in rescue
The evaluation, prognosis, and treatment of dogs that bite may be different for dogs that are in a rescue/shelter than for dogs who have a home.
In general, a dog who has a secure, long-term home with a family who is not only willing to implement management and behavior modification, but the resources to do so, will have a better prognosis than dogs who do not have a home.
When evaluating dogs in rescue, it is important to be realistic about the availability of resources (money, time, space, etc.) that will be required both before and after adoption - and whether these requirements are reasonable to ask of an adopter.
Placing dogs with bite histories
In a world in which healthy, behaviorally-sound dogs are regularly euthanized for space in shelters, the resources may simply not be available to ensure that a dog with a bite history is safe to place in a new home.
It's important to consider the type of home that a dog with a bite history will need to be safe and successful. Is finding that home realistic? Spending weeks, months, or years in a kennel environment is detrimental to a dog's physical and mental wellbeing, and it will negatively affect the dog's prognosis.
Will the management and behavior modification that the dog needs to safely live in a home be realistic for and reasonable to ask of an adopter? Putting an adopter in a situation in which they will spend thousands of dollars, make major adjustments to their lifestyle, and potentially need to make the decision to euthanize the dog for behavior down the road will almost certainly turn that adopter off from adopting again in the future.
In any case, it is absolutely vital that rescues and shelters fully disclose any dog's history of behavior, including bite incidents, to any foster or adopter considering the dog. Failing to do so is not only morally wrong, it's a legal liability that can result in the permanent termination of the organization's foster and/or adoption programs.
Preventing bites
It is extremely rare for a dog to “bite out of nowhere.” In most cases, the dog gave ample warning of their discomfort prior to biting, but those behaviors were ignored, misunderstood, or punished. Recognizing and respecting a dog’s warnings are vital to preventing dog bites.
Most dog bites that require medical treatment are to children and come from known dogs - their family dog, a neighbor or friend’s dog, etc. Teaching children how to safely interact with dogs and ensuring that children are always supervised around dogs, including family dogs, is one of the best strategies to prevent bites.