Study: Chihuahuas bite vets most; Lhaso Apsos inflict worst injuries


Lakewood, Colo. - Chihuahuas are most likely to bite veterinarians. Lhaso Apsos deliver one of the most severe bites.

Lakewood, Colo. — Chihuahuas are most likely to bite veterinarians, Lhaso Apsos deliver one of the most severe bites, and about 40 percent of all dog bites are delivered by mixed breeds.

These and other dog-bite truths are unveiled in a new study two years in the making that analyzes what kind of dogs bite and why.

The Coalition for Living Safely with Dogs and the Colorado Veterinary Medical Association released their study in May during National Dog Bite Prevention Week, and the results shed light on how likely a dog is to bite, a factor that may be pertinent to breed-specific legislation in some states and cities.

The study concludes that all dogs will bite, and that circumstances under which the bite occurred are more indicative than the breed.

Running at large was the leading circumstance under which dog bites occurred, but about half of bites happened while a dog was running at large during dog-to-dog aggression, aggression while protecting property and fear-based aggression.

Grooming and veterinarian care or kennel incidents only made up about 2 percent of reported bites.

Most happened at the dog's home, too, but dog-to-dog aggression also frequently occurred in public places.

The majority of home bites were attributed to aggression while protecting property, with owners and family members frequently bitten while the dog was protecting food or toys, compared to non-family members being bitten when a dog was protecting its property. This made up 31 percent of all non-relative bites in the home.

Breakdown by breed

Of the 188 different breeds in the survey, bites were reported from 129, including "gentle" breeds like Golden Retrievers. At least 38 percent came from mixed-breed dogs, the study notes.

The five top breeds involved in bite incidents in the study, which aims to challenge breed bans for dogs like Pit Bulls, were Labrador Retrievers (13 percent), Pit Bulls (8.4 percent), German Shepherds (7.8 percent), Rottweilers (3.9 percent) and Chow-Chows (3.5 percent).

Bites involving children brought similar results, with Labrador Retrievers responsible for 15.6 percent, Pit Bulls for 7.5 percent, German Shepherds for 6.8 percent, Smooth-Coated Chihuahuas for 4.2 percent and Rottweilers for 4.1 percent.

The severity of injuries by breed differs greatly, however, with American Bulldogs, Dalmatians, Standard Dachshunds, English Bulldogs and Lhasa Apsos delivering the most severe injuries.

The reasons for attacks also varied by breeds, with Labrador Retrievers most likely to bite when running at large or during possessive aggression. Pit Bulls were most likely to bite while running at large or during dog-on-dog aggression, and German Shepherds bit most often while running at large or protecting their property.

Other breeds, like Golden Retrievers and Border Collies, were more likely to bite while protecting property, play biting or being left unsupervised with the victim. But Smooth-Coated Chihuahuas were by far the most likely to bite during a grooming, kennel or veterinary visit, followed by Australian Shepherds and Siberian Huskies.

Whether the dogs were spayed or neutered had little effect on the study findings, except that intact dogs at large are more likely to bite, and play biting also is more frequent. But younger dogs and male dogs are more likely to bite overall, and their bites are usually more severe than a female's bite.

Other age-specific revelations were that puppies bite most when playing, adolescent dogs while running at large and older dogs while protecting property.

On the human end, dogs are more likely to bite human males than females, and bites in children usually are less severe than adult bites.

Children are most often bitten while left unsupervised with a dog, provoking a dog or as a result of play bites, while adults are more often bitten by an at-large dog, a dog protecting its property, dog-to-dog aggression or dominance-based aggression.

The study compiled the results of more than 2,000 surveys from 17 of Colorado's 134 animal-control organizations from June 2007 to June 2008.

Of the estimated 226,152 dogs in the jurisdictions, about 2,000, or 0.28 percent, of the dogs were reported to have bitten someone. Assuming data from a 1997 study of dog bites in Pittsburgh that found only 6.2 percent of bites were reported to animal control, and considering the Colorado human population of nearly 5 million, the study estimates that there are about 74,000 overall bites in Colorado during the study year.

Informed speculation

The coalition notes that, without a statewide census of the number and breed types of dogs in Colorado, as well as participation from every animal-control group in the state, some of the results don't offer true data but only enough information for informed speculation.

For instance, there may be some disparity in reports regarding breed types in the study since it indicates it's very likely that bites from large dogs are more often reported than bites from small dogs, according to the coalition.

"Because of this, the percentages of bites from large breeds will be overestimated and the percentages of bites from small breeds will be underestimated," according to the study.

Along with the study, the coalition offers advice for preventing dog bites, saying that dog owners need to be responsible for their pets and that children should be taught to interact with dogs and not be left unattended with them.

The study showed that certain breeds are more likely to bite under certain circumstances, but emphasized that any dog will bite in certain situations, though most often because of factors determined or caused by the victim.

The full study can be viewed online at

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