Are Underweight Shelter Dogs More Likely to Display Food Aggression toward Humans?

SIMPLE SUMMARY: Canine aggression over resources such as food or edible chews is commonly termed food guarding or food aggression. Food aggression directed at humans is relatively common in dogs, including dogs that enter animal shelters. While food aggression is part of dogs’ normal behavior, little is known about why some dogs show food aggression, but others do not. Common animal shelter “lore” suggests that dogs that are underweight or were previously starved are more likely than normal-weight dogs to show aggression toward a human that approaches while the dog is eating. It is assumed that the value of food to the dog is increased by experience with food scarcity, and the value remains elevated even after food is no longer scarce. We tested this common belief by analyzing data from 900 dogs from criminal cruelty cases to look for a relationship between the dogs’ weight and human-directed food aggression. Contrary to common belief, we found that underweight dogs were not more likely than normal-weight dogs to be food aggressive. Based on these results, human-directed food aggression is not a reliable indicator of past food scarcity. This has implications for criminal proceedings, as dogs can have previously experienced starvation without obvious residual behavioral indications in the shelter. ABSTRACT: It is commonly believed that underweight or emaciated dogs are predisposed to food aggression toward humans. Each year, the American Society for the Prevention of Cruelty to Animals (ASPCA) receives hundreds of dogs from criminal cruelty cases. The dogs range from emaciated to overweight. We analyzed existing data from 900 such dogs to examine the relationship between body condition score and food and chew item aggression toward humans. Across all types of cruelty cases, 9.2% of dogs were aggressive over the food, chew, or both, which is a lower prevalence than that previously reported among shelter dogs. Dogs from cruelty cases originating in New York City were more likely to show aggression over food (z = 3.91, p < 0.001) and chew items (z = 2.61, p = 0.01) than dogs from large-scale cruelty cases, although it is unclear why. Female dogs were less likely to show food (z = −3.75, p < 0.001) and chew item (z = −2.25, p = 0.02) aggression compared to males. Underweight dogs were not more likely to display food aggression, but when they did, the aggression was no more severe than that of normal-weight dogs (Fisher’s exact tests = 0.41 and 0.15 for the Food Bowl and Chew Item scenarios, respectively). Breed type was not a significant predictor of aggression. Canine food aggression does not appear to be an aberrant behavior caused by a history of food scarcity but may be related to biological factors such as sex. These findings could prove useful for animal behavior subject matter experts testifying in court or consulting on cruelty cases, as they could speak with scientific validity to the question of whether there is a link between previous food scarcity and the likelihood of food aggression in dogs.