Fly Biting in Dogs: Explaining the Top 3 Causes

Kingsdale Quick Takes

• Fly biting: sudden “air snapping” episodes.
• It often signals seizures, reflux pain, or anxiety.
• We treat the cause with anticonvulsants, antacids, or behavior therapy.
• Most dogs improve within weeks once therapy starts.
• See your vet promptly if episodes cluster or worsen.

If you’ve noticed your dog suddenly snapping at the air, as if they’re trying to catch imaginary flies, you’re witnessing what’s known as “fly biting behavior” or “fly snapping,” a common issue in fly-biting dogs. As a veterinarian, I frequently encounter pet owners who are worried about this unusual behavior. In this article, I hope to help you understand why your dog may appear to be fly biting.

What exactly is fly biting in dogs?

Fly biting, also known as fly snapping or fly catching syndrome, involves repetitive jaw snapping movements as though dogs are catching invisible insects. Studies have aimed to characterize fly biting by evaluating affected dogs and assessing how this behavior is linked to abnormal movements.

During these episodes, dogs often present abnormal movements such as head raising, neck extension, or air-licking

Common causes of fly biting behavior in dogs

Fly biting behavior can stem from various underlying medical or behavioral conditions. Here are the top 3 causes of flying biting in dogs:

Understanding the seizure activity associated with fly biting can help in diagnosing and managing the condition effectively.

1. Focal seizures

Focal seizures are a common cause of fly biting behavior! When there is abnormal electrical activity in a limited area of the brain, focal seizures can result in involuntary body movements.

When we say focal seizures, we are specifically referring to abnormal electrical activity in the brain causing these abnormal movements. Dogs with focal seizures often exhibit jaw snapping, abnormal posturing, and other changes in behavior.

This can manifest as fly biting or as if the dog is licking the air. Because these abnormal movements can be subtle and short-lived, they are not always noticed by pet owners.

What's the difference between focal seizures and generalized, "grand-mal" seizures in dogs?

Focal seizures and generalized seizures differ primarily in the extent of the brain affected by abnormal electrical activity. Focal seizures, also known as partial seizures, involve abnormal activity in a specific area of the brain, leading to localized symptoms such as fly biting behavior, jaw snapping, or other abnormal movements. Seizures caused by identifiable abnormalities within the brain, such as tumors or head trauma, are called structural seizures.

In comparison, generalized seizures affect both sides of the brain from the onset, leading to more widespread symptoms such as convulsions, loss of consciousness, and uncontrollable muscle movements.

2. Gastrointestinal (GI) disorders

Dogs are complex creatures, and it may surprise you to learn that gastrointestinal (GI) diseases like gastroesophageal reflux (GERD) or delayed gastric emptying may be the cause of that fly biting you think you see in your dog!

Acid reflux or stomach pain caused by a flaccid and distended stomach can cause these jaw snapping episodes in dogs. In most cases, you will see your dog licking their lips and swallowing hard in conjunction with the fly biting behavior. The combination of these symptoms is a strong indicator of a GI problem.

An abdominal ultrasound, physical examination, and full medical evaluation will help your vet get to the bottom of these underlying gastrointestinal issues that might be affecting your dog.

A study published in the CVJ (Frank et al., 2012) identified seven dogs that continued to exhibit fly biting behavior associated with gastrointestinal disease. Clearly, this isn’t a coincidence!

Another study published in the Journal of the American Veterinary Medical Association (Galli et al., 2024) investigated a French Bulldog whose history of fly-crazed episodes was directly linked to gastrointestinal disease secondary to gluten sensitivity, further supporting the association between GI disease and fly biting.

3. Behavioral disorders

Some fly biting behaviors can be caused by a compulsive disorder or other behaviors that can be triggered by stress, boredom, anxiety, or neuropathic pain syndromes. Dogs raised in stressful situations or lacking mental stimulation may exhibit learned behaviors in response to their situation.

How is dog fly biting diagnosed?

Determining why your dog is exhibiting fly biting behavior involves starting with a visit to your vet. They will then likely consider the following:

• A physical examination of your dog to assess their overall health and to identify any signs of pain or distress. Part of the physical exam should include a detailed neurological examination. Prior to your appointment, it would be helpful if you could capture a video of the behavior so that your vet can review it.
• An abdominal ultrasound is great for ruling out gastrointestinal disorders that might be causing the problem. Abdominal X-rays with a barium series can also be helpful.
• Your veterinarian may also recommend blood testing. These can be very helpful in determining underlying medical or metabolic disorders that might be causing the undesirable behavior. Seizures that occur due to metabolic disorders, toxins, or drug interactions are called reactive seizures and can be resolved by addressing the underlying issue.

Once we have a complete picture of what is going on, we can tell you exactly what the underlying cause is and recommend appropriate treatments for your dog.

How is fly biting treated?

Getting the right treatment means correctly identifying what’s really going on with your dog:

• Neurological conditions: These are usually treated with medications such as phenobarbital or levetiracetam. Your veterinarian will be able to tell you what the best option is for your dog. Effective seizure control often requires a combination of medications such as phenobarbital. Even with medication, some dogs may experience breakthrough seizures, which are occasional seizures that occur despite ongoing treatment.
• Treatments for gastrointestinal reflux: This involves changing your dog’s diet, taking medications to reduce acid reflux like omeprazole, and delayed gastric emptying or abdominal pain, which may be causing the behavior.
• Behavioral modification: A behavioral consultation might recommend increasing mental stimulation and trying anxiety-relieving medications. In addition, a structured training routine can help with any compulsive disorders.

When to see your veterinarian

If you notice your dog exhibiting more fly biting episodes or other abnormal behaviors, such as jaw snapping or unusual posturing, please schedule a visit with your veterinarian.

Fly biting in dogs might look amusing or harmless at first glance, but it can actually signal some serious underlying health issues. These can range from neurological disorders, like focal seizures, to gastrointestinal problems or even behavioral challenges. It's important to catch these signs early and consult your veterinarian for a proper diagnosis. With the right treatment plan—be it medication, dietary adjustments, or behavioral therapy—most dogs show significant improvement.