What is Fly Snapping Syndrome in Dogs?

Does your dog seem fine one moment, and the next she is snapping at flies in a very determined way…except there are no flies? Many dogs may also lick their front paws, but the dogs seem neither upset or disorientated during the episodes. Some dogs will seek their owner afterward or during the occurrence. So, what exactly is going on?

This strange behavior is still not 100% explained by veterinarians. While they are currently working on what may be the cause, the main thought is that it is a type of complex partial seizure, according to Dr. Dennis O’Brien DVM, PhD, Diplomate ACVIM, at the University of Missouri, U.S.A. O’Brien is a specialist in neurology and is researching canine epilepsy.

Humans who have epilepsy often see hallucinations, and so it is thought by vets that fly-biter dogs (as they are sometimes called) may be hallucinating as part of a seizure. Unfortunately, it is very difficult to map out one of these episodes using an EEG, and so definitive proof is hard to come by.

Instead, most veterinarians will put the dog on an epilepsy drug, such as phenobarbital, and see if the episodes lessen. If they do, the dog most likely has epilepsy. However, if the dog was already having very infrequent episodes, it can be hard to tell if the medicine is helping or not. Some dogs exhibiting fly biting end up having grand-mal seizures, which of course makes the epilepsy diagnosis much more probable as well.

Other Possible Causes?

There are other causes for the behavior that veterinarians at the University of Missouri, U.S.A, say are much less likely, but could still be a possibility. One theory is that the dog has a chunk of debris in the fluid of the eye, which the dog sees as a fly and tries to snap at it. However, of all the dogs they have examined with fly-biter syndrome, not one of them has ended up having something in their eye, so this theory is probably not sound.

Another theory is that the dog is having a hallucination from migraines (just as some people with migraine headaches say they experience before getting one). However, since the dogs do not seem to be in pain during an episode, they think this is not likely either. Since our dogs cannot tell us if they are pain, this is a hard one to prove or disprove.

Should I worry if my dog exhibits fly biter behavior?

Dr. O’Brien recommends watching your dog. If the episodes are infrequent, their may not be anything to worry about. But, if the episodes become more frequent or are accompanied by a grand-mal seizure, it’s time to see a vet.

The group of vets at the University of Missouri and Minnesota are working with the American Kennel Club and the Canine Health Foundation to try and better understand and document canine epilepsy, especially if it’s hereditary or more common in certain breeds. They are asking everyone to participate in their research.

There is also the International Veterinary Epilepsy Task Force. They have a set of guidelines for epilepsy research that the Australian Veterinary Association is using to try and find out more information about seizures in dogs, which may help to unravel the mystery of fly snapping syndrome.

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  1. I had a small dog who was literally terrified of flies – real ones, not imaginary ones. She would shake and snap at them, generally become a quivering mess. It was a huge problem every summer because she never wanted to go outside. I could never work out why until I had a psychic reading done on her and my other dog. Yes, a bit weird I know but….. She told the lady she hated flies because ‘before’ she had swallowed one and it ’bit’ her throat and she died. The lady told her a fly couldn’t kill her and she was adamant it had – clearly a bee. She also told her she had a really sore back. I’d had her for X-rays, scans, blood tests, you name it because I knew something was wrong with her. After the reading I took her to a Chirovet, he confirmed her spine was indeed out of alignment, she had regular treatment and was a different girl. She loved going to him. My two girls told this lady so many things that she could never have guessed just by me emailing her two pictures of them. It was amazing and I’d highly recommend it for anyone struggling to determine what is wrong with their animal.

  2. My dog sometimes has the fly biting behaviour. He is a King Charles Cavalier and is thought to have early/ mild syringomyelia. He often does the fly biting around times when he also develops apparent headaches. Luckily this is very occasional.

    1. My dog Scotty has this behaviour and he is a cross King Charles Cavalier, I’ve never had it checked out as he seems ok and I had never heard of it till this article. It might be in the breed

  3. We have a small dog. I believe he was stung by a bee couple of years ago. So any time there is a blow fly or bee he starts snapping at them. Anything that makes a noise like a bee he goes crazy.

  4. My cavalier regularly does this behaviour. Very often it is after a meal, but can occur at other times as well. The vet is stumped. She often does it when we have visitors and she’s on my lap. She needs a cuddle afterwards which makes me wonder if it is a mild seizure.

  5. Robert I have a Chihuahua she is 8 years young but when on a walk and she sees another dog she goes nuts and attacks, She will not respond to Chloe No she completley ignors my calling and continues with her charge. I know I can put her on the lead, but I would like to know what to do to stop her attacking.
    Gerry Seefeld

  6. I have a 7 yr old rescue Lhasa Apso and he has displayed episodes of Fly Snapping Syndrome in the last year. We have taken him to see Vet Specialists who have suggested that it could be either a GI problem or epileptic attack. We have tried an elimination diet by feeding him a single source of protein and observe the frequency of the attacks. They seem to happen mostly after eating and have found that a strict grain free salmon kibble seem to lessen the frequency of the fly snapping. We are still trying to figure out the triggers to this by simply observing his behaviour and food intake. It is interesting to read about other dogs with similar symptoms.

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