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Abnormal Behaviors Aren't Always Psychological

Compulsive behaviors can be caused by medical issues.

Two studies have identified gastrointestinal problems in dogs that licked surfaces excessively or engaged in fly biting behavior. Once the underlying problems were treated, the compulsive behavior in these dogs decreased or stopped altogether. These findings highlight the need to always check for medical conditions before concluding behavior problems are strictly psychological.

Ilana Reisner, DVM, PhD, DACVB
Source: Ilana Reisner, DVM, Ph.D., DACVB

As veterinary behaviorists we commonly see dogs exhibiting bizarre repetitive behaviors. Examples of repetitive behaviors seen in dogs include flank sucking, fly biting, light chasing, spinning, tail chasing, hind end checking, self-licking, and licking of objects or surfaces. These behaviors may be caused by compulsive disorders, which are described as repetitive, ritualistic behaviors that are performed excessively and interfere with normal daily activities.1 Compulsive behaviors are often initially associated with situations that cause conflict or frustration and are later displayed in other situations when the dog is agitated or excited.2 They can occupy a large percentage of a dog’s day and negatively impact the quality of life.

Treatment for compulsive disorders has mostly focused on the use of antidepressant medications as well as behavior modification strategies to interrupt and redirect the behavior to a more appropriate activity. However, a thorough history and medical evaluation are essential before diagnosis and treatment. It is especially important to investigate for and treat any medical disorders that may be causing or contributing to the behavior. For example, two recent studies have shown that in the case of some oral compulsive disorders, there may be an underlying gastrointestinal (GI) problem.

The studies, by a group of researchers at the University of Montréal Veterinary Teaching Hospital, investigated medical causes for the excessive licking of surfaces and fly biting in dogs.3,4 This research suggests that at least some of these cases are related to medical issues causing nausea or discomfort, thus triggering the odd oral behaviors.

Excessive licking study

In this study, 19 dogs that displayed excessive licking of surfaces were compared with a control group of 10 healthy dogs.3 Complete medical and behavioral histories were collected for all dogs, and they all underwent physical and neurologic examinations. Each dog then underwent a series of tests that included an abdominal ultrasound, endoscopy, and biopsies of the stomach and upper intestine. Dogs in the licking group had been licking on average for 32 months, and 16 of the 19 dogs licked daily. The medical evaluation revealed that 14 of the 19 licking dogs had GI abnormalities, which included inflammatory bowel disease, pancreatitis, and, in one dog, a foreign object in its stomach. Treatment of the underlying GI disorder resulted in significant improvements in a majority of dogs. While no disorder was identified in five dogs in the licking group, four out of these five improved with the use of a hypoallergenic diet plus antacid or anti-nausea medication.

Fly biting study

This study evaluated seven dogs that had a history of daily "fly biting" behavior.4 Fly biting is defined as a syndrome in which a dog appears to be staring at something and suddenly snaps at it. This condition can be a form of a focal seizure but was otherwise assumed to be a compulsive disorder. Each dog in this study had complete medical and behavioral histories collected in addition to undergoing physical and neurologic examinations. All of the dogs were filmed during the behavioral assessment and for two hours after a meal to evaluate the fly biting behavior. Blood and urine testing were performed in all dogs, and if there was a history of GI signs, a complete GI evaluation was performed. The behavioral histories of these dogs revealed that the fly biting had been present from six days to four years prior to the study and that the behavior occurred from once daily to once every hour. The videos revealed that all dogs raised their heads and extended their necks prior to fly biting, which may suggest esophageal discomfort. All dogs in this study were diagnosed with a GI abnormality, and one dog was also diagnosed with Chiari malformation (a condition in which brain tissue extends into the spinal canal5). Six of the seven dogs responded to medical treatment alone, and the fly biting behavior stopped completely in four dogs. No anti-anxiety medications were administered with treatment for the GI issues.

Both studies reveal that GI disease can cause excessive licking or fly biting and that these behaviors were significantly reduced with appropriate treatment of the GI issues. However, the take-home message here is not that compulsive disorders with a primary behavioral cause do not exist. Rather, not all compulsive behaviors are strictly behavioral. If your dog or cat exhibits an abnormal repetitive behavior, bring him or her to your veterinarian for a medical evaluation. If possible, bring a video of the behavior to the appointment. The medical evaluation should include a physical and neurologic examination as well as bloodwork and urinalysis to investigate for several conditions that can be responsible for repetitive behaviors. Based on the findings of two studies above, if your dog licks excessively or fly bites, a thorough GI workup is also indicated. Depending on the diagnosis, treatment may include a hypoallergenic diet, antibiotics, anti-inflammatory drugs, or antacids.

Kelly Ballantyne, DVM, DACVB, University of Illinois College of Veterinary Medicine;

John Ciribassi, DVM, DACVB, Chicagoland Veterinary Behavior Consultants;

Kelly Ballantyne, DVM, DACVB
Source: Kelly Ballantyne, DVM, DACVB
John Ciribassi, DVM, DACVB
Source: John Ciribassi, DVM, DACVB


1. Overall KL, Dunham AE. Clinical features and outcome in dogs and cats with obsessive-compulsive disorder: 126 Cases (1989-2000). J Am Vet Med Assoc 2002;221(110):1445-1452.

2. Mason G, Rushen J. Veterinary and Pharmacological Approaches to Abnormal Repetitive Behaviour. Stereotypic animal behaviour. 2nd ed. Oxfordshire, UK: CABI; 2006: 286-384.

3. Bécuwe-Bonnet V, Bélanger MC, Frank D, et al. Gastrointestinal disorders in dogs with excessive licking of surfaces. J Vet Behav 2012;7(4):194-204.

4. Frank D, Bélanger MC, Bécuwe-Bonnet V, et al. Prospective medical evaluation of 7 dogs presented with fly biting. Can Vet J 2012;53:1279-1284.

5. Plessas IN, Rusbridge C, Driver CJ, et al. Long-term outcome of Cavalier King Charles spaniel dogs with clinical signs associated with Chiari-like malformation and syringomyelia. Vet Rec 2012;171(20):501.

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