How I treat food-related aggression in dogs

2007-04-01
Jacqueline C. Neilson, DVM, DACVB

Diagnosing food-related aggression in dogs is fairly straightforward--the history reveals that a dog in possession or proximity of a food item directs a threat or harmful action toward another with the intent of backing that individual away from the food item.

Diagnosing food-related aggression in dogs is fairly straightforward—the history reveals that a dog in possession or proximity of a food item directs a threat or harmful action toward another with the intent of backing that individual away from the food item.1 Some dogs aggress over only certain types of food or treats (e.g. palatable human food, rawhide), while others aggress around any food item or even an empty food bowl. The specific actions of a dog during a food-aggressive event can vary from low-level threats such as body stiffening to high-intensity aggression such as biting.

SIGNS OF FOOD-RELATED AGGRESSION

Typically, the dog initially stiffens its body, particularly its shoulders and neck, and holds its head downward, hovering over and guarding its food item (Figure 1). The dog's pupils will dilate, and the eyes may widen so that the whites are visible. The dog's eyes may dart about if there are multiple threats or be fixed in a stare on a single threat. The tail position may vary based on breed, but it is often stiff and either down or tucked. The ears are usually pulled slightly back. Piloerection may occur as the threat intensifies. The dog may freeze in this hunched position until the threat intensifies (person gets closer, maintains eye contact).

1. A dog with a treat exhibits signs of aggression as a person approaches. The dog is tense and hunched down over the food item, with dilated pupils and a slightly lifted lip. A few moments later the dog lunged, growled, and snapped at the person.

It is important for owners to recognize the initial signs of their dogs' tension or aggression, such as body stiffening, eye changes, and hunching over the food. If these body postures are noted, the dog is feeling threatened, and if the issue isn't addressed appropriately, the aggression may escalate into growling, snarling, snapping, or biting. Often the dog engages in just enough of an aggressive display to get the person to back away and then returns to the food item it was guarding. If the dog has had the problem for a long time or the owner has tried inappropriate interventions, the aggressive response may become more intense and dangerous.

ARE OTHER AGGRESSIVE BEHAVIORS PRESENT?

While the scope of this article is limited to food-related aggression, you should also ask clients about other circumstances in which the dog shows aggressive behavior. If such circumstances are identified, the dog's behavior in those situations must also be addressed. In many cases, you will identify a common thread in the triggers for aggression, such as the dog perceiving a threat to a variety of valuable resources. Those resources may include resting spots, personal space, or toys. It is critical to remember that while an owner's intent is not to threaten the resource, the dog's perspective regarding the owner's action is what is important. Questions relating to the dog's overall confidence and behavior in various situations will also help discern a potential underlying motivation for the aggression. A dog that is nervous or anxious in other situations may be more anxious about activity around its valued food resource.

IS FOOD AGGRESSION A QUESTION OF DOMINANCE?

Based on a dog's history of food-related aggression, some owners will immediately characterize the dog as a dominant, or alpha, dog, implying that the dog is the leader of the household; however, this characterization is too simplistic.2 While some of these dogs may be confident dogs that compete for the food resource by using aggression since neither party involved will defer, many food-aggressive dogs show some ambivalence or fearful or uncertain behaviors either during the event or in other contexts. This behavior suggests that many food-aggressive dogs are motivated by fear and anxiety and are not confident leaders.

IS FOOD AGGRESSION ABNORMAL?

When dealing with aggression, it can help to consider just how pathologic the behavior actually is. Although food aggression is undesirable in a pet, it may not be aberrant for a dog to protect a food resource from a perceived threat. Food is necessary for survival, and when a primary resource is threatened, aggression may be a viable way to remove the threat. When the aggressive behavior is successful, the dog experiences negative reinforcement (aggression drives away the threatening stimulus), and the behavior is more likely to be repeated.3 Instead of debating whether food aggression is truly deviant behavior, the more pertinent issue is how owners may aggravate their dogs' inherent drive to protect food and therefore escalate the problem.

DO OWNERS CREATE FOOD AGGRESSION?

Owners may inadvertently exacerbate their dogs' protective or aggressive behavior around food items in several ways.

Feeding palatable food

Giving dogs highly palatable food may elevate their desire to protect it.

Allowing free-choice feeding

Providing free-choice food or long-lasting food items (e.g. rawhide) may cause a pet to constantly protect the food resource. Free-choice feeding also creates more potential threats to the food item—if food is present all the time, then people in the home are more likely to inadvertently or intentionally violate the item.

A competing argument is that by making food available at all times, it reduces its value and, thus, a dog's need to protect it. Given ad libitum access to food, dogs will generally eat a few meals during daylight hours,4 so dogs on too infrequent of a feeding schedule (e.g. one meal a day) may get hungry between meals, thus making the food more valuable.

A dog's underlying temperament and the palatability of the food item may dictate how free-choice feeding affects food aggression.

Feeding in a busy location

Pet feeding locations are often in highly trafficked household zones (e.g. in the kitchen), which may inadvertently create a scenario in which the dog feels constant threats as family members walk near its food.

Using inappropriate prevention techniques

Some of the standard recommendations to prevent food aggression in puppies may actually create the problem in dogs with a high food drive or a nervous temperament. One common recommendation is to take the food bowl away periodically as the pup eats. However, in my experience, the only thing that this action teaches the pup is that something undesirable is likely to happen when people approach as it is eating—they may snatch the food. Even if the removal of food is paired with a reward, the dog may still consider the abrupt removal of its food more threatening than any benefits from the reward.

Another common suggestion is to sit with a hand in the pup's bowl as it eats, thus getting it habituated to the close presence of people during meal times. Once again, a dog with a nervous temperament or a high food drive may consider this action too threatening and become sensitized (more reactive) instead of habituated (less reactive) to the situation.

Some clients may appreciate that these situations are analogous to dining out with an overeager waiter who hovers around the table and attempts to remove your plate when you take a brief respite from eating. If the waiter does this with each course, you may become tense every time the waiter approaches your table, even if it is only to refill your water or breadbasket. In fact, you may alter your body posture to guard your plate, especially the dessert! While it is unlikely that most people would lash out at the waiter, it is not improbable for the diner to complain to the maitre d' or leave a minimal tip. The dog's communication tools are limited and less inhibited by social etiquette, so aggression may be the equivalent response from the dog toward the owner who is threatening its meal.

APPROPRIATE INTERVENTIONS

Avoidance

The best treatment for food-related aggression is avoidance (i.e. avoid placing the dog in situations in which it is likely to aggress). Often by the time an owner reports the problem to a veterinarian, the dog is so stressed around the food item that any intervention at that point will fail. For some dogs, avoidance can be a lifelong program. For others, the situation will dictate behavioral modification, but that should not be instituted until the owner has used avoidance for a period sufficient to reduce the dog's anxiety, usually a minimum of four weeks.

For a dog that aggresses around its own food bowl, avoidance is relatively simple to implement. The dog is fed its meals behind a secure, closed door. Once the dog has finished eating, it is let out of the room, and the owner can retrieve the bowl and any remaining food when the dog is not in the vicinity.

If a dog aggresses with long-lasting food treats (e.g. rawhide), then these treats should no longer be given. If the dog needs an outlet for appropriate oral activity, other lower-value items can be tried. If these fail to interest the dog or they evoke aggression, then either the dog should not receive long-lasting food treats at all or the dog should only receive them when secured behind a closed door. Giving the dog nonfood-related outlets for play and exploration such as toys and leashed walks may reduce its need for oral activity.

For dogs that aggress only around dropped human food, avoidance and a "drop-it" command can be used. Situations likely to generate triggers should be avoided. Household food rules for people may be required such as only eating at a table or segregating the dog from all food preparation and eating areas. If a food item does come into the dog's possession, removal should not even be attempted, since in many instances the risk associated with the dog consuming the food item is lower than the risk associated with attempted removal.

The "drop-it" or "leave-it" command gives owners a constructive option to recover items from their dogs. For this command to work in situations involving food, it must first be mastered in less-challenging situations. Most dogs can learn these commands with a reward-based training approach. Most obedience programs and basic obedience books outline steps to accomplish this task. Once well-established, the command can be an effective way to handle potentially aggressive situations.

Another removal option is bribery, which may be prudent in situations in which the dog is at risk of injury from ingesting the item and does not have a reliable "drop-it" command established. In this case, the dog is shown a more palatable item and then is lured away from the dangerous food item. Once a barrier separates the dog from the dangerous item, the dog is given the bribe, and another person can retrieve the dangerous item. Using bribery on a routine basis is not advised since it ultimately rewards the aggressive behavior.

Desensitization and counterconditioning

For many dogs, desensitization and counterconditioning is not necessary; avoidance is a superior long-term treatment option. Some risk is involved with desensitization and counterconditioning since a misstep could result in aggression and injury to the owners. It is best not to attempt this treatment until avoidance strategies have been implemented successfully and at least a month has passed without confrontations over food items.

To start, identify a training gradient, which may include such things as the value of the food item (start with low-value items) or owner distance from the dog or food item (start far away). The basic premise is to keep the dog below its aggression threshold by using gradients and rewarding the dog for nonaggressive behavior. With success, the gradients can be gradually adjusted to increase the relative threat to the dog but always keeping the threat below the aggression threshold. With continued rewards for owner approach and nonaggressive behavior, the dog learns that owner proximity to the food item is not a threat and is actually rewarding.

For example, if a dog exhibits aggression when the owner comes within a 5-ft radius of its food bowl, the owner should start by placing the bowl on the floor with a small amount of food. The owner then approaches but stops 6 ft from the dog or bowl. With the dog calm and relaxed, the owner tosses it a fabulous small treat. The owner then retreats and repeats the sequence. Over multiple sessions, the owner should be able to gradually get closer to the dog and its food bowl without evoking a negative response.

If the dog's aggression threshold is inadvertently triggered during training, the owner should calmly retreat and, at the next training session, adjust the distance to keep the threat below the dog's threshold.

Ancillary treatments

Households with minimal structure may benefit from providing clear direction to the dog by using command-and-reward-based interactions. Make sure owners know that adequate exercise is important for every dog's health. In addition, dogs with anxiety may benefit from synthetic pheromones (Dog Appeasing Pheromone [D.A.P.]—Ceva Santé Animale) and serotoninergic drugs, although neither of these treatments has been systematically studied in the context of food-related aggression. Since avoidance can be such a successful tool in managing this condition, drug intervention may not be warranted. Also, it is important to note that any drug that causes an increase in appetite may aggravate food aggression and should be avoided if feasible.

INAPPROPRIATE INTERVENTIONS

Owners should avoid direct confrontational intervention (hitting, yelling, physical restraint) when the dog exhibits aggression. While this action may interrupt the aggressive behavior at that moment, it is unlikely to resolve the problem in the long run, especially if the dog is anxious. In fact, direct confrontation may lead to intensification of the aggressive display both at the moment of confrontation and in the future. If people approaching a dog's food item becomes a predictor of confrontation, the dog may become more anxious and dangerous, so direct confrontation must be avoided.

CONCLUSION

Food-related aggression is a common problem that owners may inadvertently aggravate. Thus, veterinary staff members should provide owners with information during puppy visits about how to avoid exacerbating this condition. If a dog presents with food aggression, simple avoidance can be a successful tool in managing the problem behavior.

Jacqueline C. Neilson, DVM, DACVB

Animal Behavior Clinic

809 S.E. Powell Blvd.

Portland, OR 97202

REFERENCES

1. Beaver B. The veterinarian's encyclopedia of animal behavior. Ames: Iowa State University Press, 1994;6-7.

2. Resiner I. An overview of aggression. In: Horwitz D, Mills D, Heath S, eds. BSAVA manual of canine and feline behavioural medicine. Gloucester, England: BSAVA, 2002;181-194.

3. Landsberg G, Hunthausen W, Ackerman L. Handbook of behavior problems of the dog and cat. 2nd ed. Philadelphia, Pa: WB Saunders Co, 2003;110-111.

4. Mugford RA. External influences on the feeding of carnivores. In: Kare MR, Maller O, eds. The chemical senses and nutrition. New York, NY: Academic Press, 1977;25-50.