SYMPTOM
Fly-biting or snapping at the air
The dog suddenly snaps or bites at the air as though catching an invisible fly, sometimes with lip-licking, swallowing, or jumping, in brief repeated episodes that can occur singly or in clusters through the day.
Focal Seizure Activity
Abnormal electrical activity in the brain (a focal seizure) is one proposed cause of air-snapping, sometimes with lip-smacking, salivation, or a brief period of altered awareness. In a multicentre series of 24 dogs with fly-catching, EEG showed spike activity in 8 of the 21 dogs tested, 7 of them over the occipital lobes, which process vision, and about a third of the dogs given an anti-seizure drug responded. The cause remained unclear in most dogs in that series.
Gastrointestinal Disease
In a small prospective series of seven dogs presented for fly-biting, gastrointestinal disease was the commonest medical finding, mostly lymphoplasmacytic or eosinophilic inflammation of the stomach or small intestine, with gastro-oesophageal reflux or delayed stomach emptying in some dogs. Nausea or gut discomfort is thought to trigger the air-snapping and lip-licking, and the episodes stopped in several dogs once the gut disease was treated. Episodes may cluster around mealtimes or alongside other digestive signs.
Chiari-like Malformation and Syringomyelia
In the multicentre series of 24 dogs with fly-catching, MRI showed Chiari-like malformation in 6 of the 21 dogs scanned and syringomyelia in 1, and the malformation was also found in a Cavalier King Charles Spaniel in the seven-dog series. Abnormal nerve sensation is a proposed link, but a causal role has not been shown. Cavaliers with a large syrinx often show phantom scratching towards the neck or shoulder and dislike being touched around the head, neck or shoulders.
Compulsive Behaviour
In some dogs, air-snapping develops as a repetitive, stereotyped behaviour that intensifies with stress, frustration, or understimulation, becoming self-reinforcing over time in the way other compulsive behaviours can. This pattern is more likely when episodes correlate with periods of confinement, boredom, or heightened arousal.
Stress or Frustration-Related Behaviour
Situational stress, such as barrier frustration or an inability to access something the dog wants, can trigger episodic air-snapping in some dogs without an underlying medical driver. Distinguishing this from a compulsive or medical pattern usually depends on how consistently it correlates with an identifiable trigger.
Why timing matters
Early observation
Early episodes are often brief, infrequent, and easily interrupted by calling the dog's name or offering a distraction. At this stage the behaviour is easy to dismiss as an isolated quirk.
Later presentation
A more established pattern shows episodes becoming more frequent, longer, harder to interrupt, or occurring in clusters through the day, sometimes alongside other behavioural or digestive changes.
A pattern that escalates over weeks to months does not on its own separate the causes, since compulsive behaviour can also intensify over time, and a pattern that stays stable and tied to clear situations fits a stress-related origin but does not rule out a medical one.
Conditions commonly associated
Epilepsy in Dogs
Focal seizure activity, mostly over the occipital (visual) region of the brain, has been found on EEG in some dogs that snap at the air.
Inflammatory Bowel Disease in Dogs
Chronic inflammation of the stomach or small intestine, the pattern seen in inflammatory bowel disease, was the commonest finding in a small series of dogs presented for fly-biting.
Syringomyelia
Chiari-like malformation, sometimes with syringomyelia, has been found on MRI in some dogs that snap at the air, including a Cavalier King Charles Spaniel, although it has not been shown to cause the behaviour.
Compulsive Behaviour in Dogs
Air-snapping can develop into a self-reinforcing, repetitive behaviour pattern consistent with compulsive disorder in some dogs.
Generalised Anxiety in Dogs
Underlying anxiety or situational stress can trigger episodic air-snapping independent of a structural or gastrointestinal cause.
Gastroenteritis in Dogs
Nausea or discomfort from gut inflammation is one proposed driver of air-snapping, although the gut problems reported in dogs presented for fly-biting were long-standing (chronic inflammation, gastro-oesophageal reflux and delayed stomach emptying) rather than a short-lived gastroenteritis.
Lymphoplasmacytic Enteritis
Lymphoplasmacytic inflammation of the stomach or small intestine was among the findings in a small series of dogs presented for fly-biting, with nausea or abdominal discomfort the proposed link to repetitive snapping or swallowing.
When to explore further
Episodes that occur alongside other seizure-associated signs, such as a blank stare, disorientation, or a period of confusion afterwards, point towards a seizure-related process worth characterising in more detail. An increase in frequency or duration on its own does not separate a seizure-related cause from the others.
A small or toy breed, particularly a Cavalier King Charles Spaniel, showing this behaviour alongside neck scratching, apparent neck discomfort, or reluctance to be touched around the head or neck matches the signs seen with Chiari-like malformation and syringomyelia.
Episodes clustering around mealtimes, or accompanied by lip-licking, drooling, or vomiting, suggest a possible gastrointestinal association worth noting alongside the air-snapping itself.
Episodes that reliably follow a specific trigger, such as confinement, understimulation, or barrier frustration, point towards a stress or compulsive pattern, although a clear trigger does not rule out an underlying medical cause.
A dog that cannot be distracted or interrupted mid-episode, compared with one that responds readily to being called or offered a distraction, is a distinction worth noting when characterising the pattern.
Video of several episodes, capturing duration, what preceded them (mealtime, rest, excitement or confinement), and whether the dog can be distracted or interrupted, adds detail that's difficult to recall accurately afterwards. A simple log of frequency and time of day, alongside notes on any concurrent neck scratching, digestive signs, or disorientation following an episode, and awareness of breed-relevant risk factors, builds a more complete picture over time.
Last reviewed: 9 October 2026 · Dr Alastair Greenway MRCVS