An aggressive dog could be in pain

We all know it's important to take care when approaching an injured animal – but the results of a new study suggest that aggressive dog behavior that might seem to "come out of nowhere" could actually stem from physical pain humans aren't aware of.

Dogs can be, or become, aggressive for any number of other reasons: how a puppy is handled and socialized, diet and/or exercise, punishment used as a training technique, even the dog's mother's condition while she was pregnant. But a study undertaken between 2010 and 2011 at the Autonomous University of Barcelona's Animal and Food Science department investigated the symptoms of 12 dogs of varying sizes, and analyzed their aggression problems. A piece on the study in Science Daily listed the breeds included – a Giant Schnauzer, an Irish Setter, a Pit Bull, a Dalmatian, a Chow, a Shih-Tzu, and two German Shepherds, among others – and quoted Tomás Camps, who's the lead author of the study, about the diagnoses. "All (eleven males and one female) were diagnosed as having aggression caused by pain," Camps said, "[and] out of the 12 studied, eight had suffered a hip dysplasia."

The article has been published in the Journal of Veterinary Behavior; Camps is a researcher at the Animal Nutrition and Welfare Service of the UAB.

Hip dysplasia is a sadly common condition among certain larger breeds; the condition is hereditary and degenerative, and affects the joint that connects the hip and the head of the femur (the "thigh"). It's thought to affect well over a third of Golden Retrievers, Labs, and Rottweilers, and can present in any breed of large dog. It's less frequently seen in smaller breeds.

The study focused on situations that were the most likely to see dogs becoming aggressive, what became a target most frequently, and whether the dogs signaled "an imminent attack." One result the study found: dogs that hadn't been aggressive before tended to attack without growling or otherwise signaling first. In noting that the animals would "quickly act aggressively" when handled in a way that caused pain, the researchers noted the importance of diagnosing and treating dysplasia and other painful conditions in a timely fashion; an owner who's unaware that her dog is feeling "ouchy" could get bitten and not know why. The research seems to indicate, as Camps notes, that pain "can cause aggression or worsen aggression problems."

If your dog is one of the breeds listed above; is a senior dog; or has acted aggressively for any or no reason; or if you have questions about the study or the symptoms of hip dysplasia, please call your vet ASAP.

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