Dog Bite | Animal Behavior Expert Witness For Attorneys

Richard H. Polsky, Ph.D. CDBC
Los Angeles, California

“Bringing the science of animal behavior to attorneys”

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Dog expert testimony in CA dog bite lawsuit | A Case Study

dog expert testimony
Dog expert testimony can be pivotal in determining outcome in dog bite lawsuits, particularly when the versions of events differ between the defendant and plaintiff.

Retaining the services of an animal behaviorist to render dog expert testimony often is a value  in lawsuits involving personal injury caused by canines.  However, attorneys handling the dog bite cases may not fully understand the need or the role of the animal behavior expert.  In this post I will describe testimony and opinions that can be rendered by an individual with expertise in canine behavior.

In particular, the opinions and testimony of an animal behavior expert are particularly relevant in California and other states which have strict liability laws for dog bites. There are several reasons for this:

Example of a dog bite lawsuit in which the versions of events differed between the plaintiff and defendant

The incident under review involved a 4-year-old, a 75 lb. male Labrador retriever dog, named Bentley, owned by defendants and the dog named Trudy, a 3-year-old, 64 lb. female Siberian husky mix dog owned by the plaintiff.

The plaintiff testified that the incident happened in the early morning when Bentley charged towards her, and attacked both her and Trudy while she was in her garage just prior to taking Trudy on leash for a walk. The plaintiff testified that both she and Trudy were bitten.

In contrast,  the defendant testified that the incident happened in the early afternoon, and that Bentley did not physically contact either the plaintiff or Trudy. According to the defendant, only a brief, nonphysical aggressive interaction happened between Bentley and Trudy in the driveway of the plaintiff, and not in the plaintiff’s garage. He testified that the plaintiff fell in her driveway shortly after the interaction between the dogs ended.

Both the plaintiff and defendant agree that the incident happened shortly after the plaintiff’s garage door opened. When the garage door opened, the defendant testify that he was positioned on the driveway of  the plaintiff approximately 20 feet from the garage, with Bentley was off-leash in close proximity  to the defendant.  According to the defendant, after the garage door opened, the dogs engaged in an aggressive standoff, less than 10 seconds in duration and approximately a foot from each other on the driveway of  the plaintiff. The dogs did not make physical contact with each other, however. Rather, the dogs only growled at each other. Shortly after the growling started, according to the defendant, he and the plaintiff separated the dogs.  Shortly after that, the defendant noticed the plaintiff laying on the ground near her garage.

The version of  the plaintiff differed markedly from that of  the defendant.  The plaintiff testified that the incident happened in the early morning, at approximately 7:30 am. She testified that immediately after the garage door opened, Bentley charged towards her and Trudy while they were in the garage. Trudy was on a leash.  The plaintiff testified that the defendant’s dog,  unleashed, rushed towards her, knocked her to the ground and then started biting her feet.

When this happened, the plaintiff testified that she tried to protect Trudy by repeatedly pulling Trudy away from Bentley with the leash that was attached to Trudy’s collar. Throughout the entire encounter, Trudy remained positioned on the right side of  the plaintiff. The plaintiff testified that the defendant’s dog bit her on both feet, and on her wrists. The plaintiff’s dog also sustained bite injuries.

The plaintiff testified that the incident ended when  the defendant entered the garage and pulled Bentley away from the plaintiff and Trudy.  The plaintiff testified that after the incident ended she picked herself up off up from the garage floor and re-entered her home with her dog.

Dog expert testimony & opinions

In cases like this where the testimony is so markedly different, dog expert testimony can be of benefit to reconstruct how the incident likely happened.  Based on the totality of the evidence, the following conclusions were reached:

  1. After the garage door opened, Trudy was restrained by the leash  the plaintiff was holding, and therefore did not have the opportunity to leave the garage and aggressively confront Bentley. She was in the process of taking Trudy for a walk. On the other hand, Bentley was off leash, and the attention of  the defendant was not on his dog but rather primarily focused on the lemon tree that he was trimming. Bentley, who was unrestrained, had the opportunity to initiated contact with  the plaintiff and her dog, and this contact therefore must have happened in the garage and not on the driveway.
  2. The plaintiff’s dog was utilized by her as a companion/service dog. Hence, it is improbable that this dog possessed the motivation to viciously charge defendant’s dog to start a fight.
  3. Bentley, in contrast, more likely than not possessed the motivational tendencies to charge an unfamiliar dog or person he suddenly noticed. After the garage door opened, he noticed  the plaintiff and Trudy, and when this happened he was impulsively driven to charge  the plaintiff and Trudy due to factors consistent with his temperament.
  4. The fact that Bentley could not be adequately controlled by the defendants, and was impulsive in nature, is further supported by the observations of  the plaintiff on the day after the incident.  She testified that she saw the defendants chasing Bentley who was running off leash. Moreover, on the day the incident happened, according to the testimony of the plaintiff,  the defendant asked the plaintiff if she wanted Bentley tied up so that she could walk Trudy. This remark indicates that the defendant knew that she could not adequately control Bentley when he was off leash.
  5. The defendant testified that there was no physical altercation between the dogs, but this testimony must be seriously questioned. For example, this testimony is inconsistent with the behavioral changes that occurred in Trudy post incident. Namely, the temperament of Trudy changed in that she started to become aggressive towards other dogs. The etiology of this kind of post-traumatic stress in dogs only happens as a result of a negative experience a dog has had because it was attacked by another dog. The defendant paid $5000 for behavior rehabilitation services for Trudy to correct this problem. Hence, the testimony of the defendant that there was only an aggressive standoff between the dogs in the driveway is not tenable.
  6. Moreover, the credibility of  the defendant’s testimony must be questioned because Trudy was treated for dog bite injury approximately one week after the incident happened. Hence, rather than an aggressive standoff between the dogs, as the defendant asserts, there must have been physical contact between Bentley and Trudy, and this physical contact, as stated above, must have happened in the garage.
  7. The plaintiff testified that she tried to protect Trudy from Bentley by repeatedly pulling Trudy away from Bentley with the leash that was attached to Trudy’s collar.  The plaintiff testified that she tried to pull as hard as she she could, and this forceful pulling on the collar is the only conceivable reason why the collar broke. The fact that the collar broke adds further support to the belief that the plaintiff and Trudy were attacked by Bentley in the garage.
  8. The plaintiff testified that the incident happened in the early morning. However, this testimony this conflicts with the testimony of a defendant. The defendant testified that the incident happened in the early afternoon. Nonetheless, the testimony of the plaintiff seems more credible since dog owners often walk their dogs first thing in the morning.
  9. Photographs of the injury sustained by  the plaintiff clearly indicates that some of injuries were the result of a dog bite.
  10. The fact that  the plaintiff sustained dog bite injury is further supported by the fact that she received a tetanus shot following the incident. Moreover, documentation from  an Urgent Care Facility, as well as from other medical providers, indicate that  the plaintiff sustained a dog bite injury.
  11. The behavior of Bentley suggests that he must have inflicted dog bite injury to  the plaintiff.  First, Bentley was in the motivational state conducive to inflict dog bite injury. For example, according to  the plaintiff, he came running towards her and Trudy, and he snarled and growled at them before attacking. Second, Trudy sustained dog bite injury, and Trudy lunged and bit Bentley during the incident. The biting behavior of Trudy towards Bentley makes it likely that Bentley also engaged in reciprocal biting behavior towards  the plaintiff and her dog.
  12. The dog bite injuries inflicted to the plaintiff must have been caused by the defendant’s dog.  Since the plaintiff’s dog was supposedly was leashed on the right side of the plaintiff during the incident, she was not in a position to inflict a dog bite to the plaintiff’s feet.
  13. The rules and regulations set forth by the  condo association in which the dogs were living clearly state that dogs must be leashed at all times when on the grounds of the Association.  The defendant violated this regulation on the day the incident in question. Leash laws are used to protect the public from unruly and aggressive dogs. the failure of the defendant to comply with this regulation allow this incident to happen.


  •  The incident must have happened in the garage of the plaintiff and not in her driveway;
  •  The plaintiff sustained dog bite injury inflicted by the defendant’s dog;
  •  The incident could have been prevented had the defendant complied with the rules and regulations set forth by the Condo association.
  • The plaintiff’s version is fully believable, given the temperament of the dogs involved and the circumstances present at the time of the incident.


 The above is taken from an expert report produced by Richard Polsky, Ph.D.  Dr. Polsky is available for assignments to proffer dog expert testimony in California and throughout the USA.


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