A dog's constant, repetitive licking of objects or surfaces is a problem whose frequency is difficult to determine. This licking may occur often, but because it seems harmless and may only be somewhat annoying, many owners accept this unusual behavior or simply ignore it. However, some owners will inquire about it during a routine checkup and ask for advice.
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Such owners often describe a dog that licks floors, carpets, walls, furniture, its own lips, and even the owner's legs, hands, or arms constantly. When not a result of an underlying medical problem, the behavior is unlikely to cause harm. However, if hair and fibers are ingested, constant licking can potentially result in life-threatening intestinal blockage that requires surgical intervention.
This article will help you identify the reason a dog licks surfaces excessively and treat this condition. I only focus on the licking of surfaces in the environment and do not cover excessive self-licking, such as that resulting in acral lick dermatitis.
DEFINING THE PROBLEM
The first and most important step when presented with a dog that licks excessively is to define the behavior as accurately as possible. Excessive licking must be differentiated from pica. An observant owner can usually describe exactly what behavior the dog is performing. Some dogs may exhibit the behavior in the veterinary clinic, but their tendency to do so or not is unlikely to be diagnostic. If there is any doubt about what behavior the dog is performing, videotaping the dog in its home can be useful. Instruct clients to collect 10 to 15 minutes of their dogs performing the behavior, both with and without the owners interrupting the behavior.
Although some dogs may only lick objects excessively, others may exhibit pica and excessive licking as part of the same set of behaviors. The potential medical causes and treatment of pica have been well-covered elsewhere, so they are not included here.1
Once you have determined that the problem is limited to excessive licking, collect a thorough history, including the age of onset, the length and frequency of licking episodes, any changes in the frequency or intensity of the behavior, and any stimuli that appear to lead to the behavior (see "Ask owners to keep a record of behavior problems"). If no external stimuli appear to provoke the behavior and it is a relatively new behavior, then a medical cause may be likely.
Ask owners to keep a record of behavior problems
Ask clients if the behavior can be interrupted, and if so, how do they interrupt it (yelling, physically stopping the behavior, chasing the animal away). A behavior that is difficult to interrupt may be more likely to be caused by a medical condition that causes distress than is a behavior that is easily interrupted. However, a true compulsive disorder that has been present for months or years may also be difficult to interrupt. Once interrupted, how long before the dog begins licking again? A dog that immediately returns to licking after a brief interruption may be in physiologic distress or demonstrating a compulsive disorder.
Collect information pertaining to the dog's general behavior and temperament to help determine if the dog has a history of anxiety or other repetitive behaviors and under what circumstances they have occurred. If possible, the owner should also try to determine if any related animals exhibit similar repetitive behaviors. Stereotypies and many medical conditions may have a genetic basis (e.g. seizures), so identifying related animals with similar behaviors may help narrow the differential diagnoses list.
Ask owners how their dogs spend a typical day, including how much and what type of interactions the pets have with individuals and other pets living in the household. A lack of exercise or unpredictable or frightening interactions with people or animals are situations that could lead to anxiety, conflict, or frustration, resulting in a behavior problem. In addition, note any changes in the environment or owners' schedules since such changes can also contribute to behavior problems.
Finally, nausea is a common cause of excessive licking of surfaces, so a detailed history should include questions about the dog's diet (type, amount, and frequency fed), treats, and table scraps and any medications or supplements the dog is receiving. Do not assume that since you have not prescribed any medications lately, the dog is not receiving anything that would make it nauseated. It is increasingly common for owners to give their pets supplements, table scraps, raw meat, or bones and not think it is important enough to mention to you.
If medications have been prescribed recently, be aware of which ones are likely to cause nausea, especially when given on an empty stomach. Many oral medications, such as nonsteroidal anti-inflammatory drugs, metronidazole, and griseofulvin, can lead to nausea. In addition, many oral antibiotics, such as cephalosporins, penicillins, tetracycline, and erythromycin, can cause gastrointestinal upset, especially if given on an empty stomach. Always ask clients whether they are giving these medications with food.