Flycatcher's Syndrome in
Cavalier King Charles Spaniels
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Cavalier King Charles spaniels are pre-disposed to a disorder called flycatcher's syndrome*. It is believed to be caused by a mutation in a specific gene which the dogs have inherited from their parents. There are two apparently conflicting theories as to its classification: it either is a complex partial epileptic seizure, due to hallucinations, or it is a compulsive disorder. See Epilepsy for a discussion of epileptic seizures in CKCSs.
* See Neurological diseases of the Cavalier King Charles spaniel. It is also referred to as fly biting.
The flycatcher's-affected cavalier appears to be watching imaginary flies buzzing in front of its face and then trying to bite the flies. Some affected dogs may compulsively chase their tails or act as if their ears or paws are irritated. Episodes may last for several hours, and in severe cases, constantly. Click here or on the YouTube logo (right) to see videos of cavaliers with watching and biting imaginary flies.
One study has indicated that gastrointestinal (GI) diseases may underlie the cause of some cases of flycatcher's syndrome, so digestive disorder symptoms may be related.
Fly biting behavior also has been identified as a symptom of syringomyelia, a serious neurological disorder more common in the cavalier King Charles spaniel than in any other breed. See Syringomyelia for information about this disease.
Diagnosing begins by ruling out other causes for the behavior. A video recording of an episode is helpful to the veterinarian. If epilepsy is the suspected disorder, advanced imaging, such as magnetic resonance imaging (MRI) or computed tomography (CT) scans, is necessary to image the brain and enable the veterinarians to diagnose diseases such as brain tumors or hydrocephalus (water on the brain) which can cause seizures. Apart from the electroencephalogram (EEG) or MRI or CT scans, there is no health test for epilepsy.
Some researchers have suggested that fly catching in cavaliers may be associated with another disorder unique to the breed, called "idiopathic asymptomatic thrombocytopenia", an abnormally low number of blood platelets. Drs. Jens Häggström and Clarence Kvart of Sweden have noted in a 1997 article that thromboembolic events in the cerebral circulation of blood may be involved in fly catching. See Blood Platelets for more information.
In a November 2012 study, a team of Canadian researchers studied seven fly-biting dogs -- including two cavalier King Charles spaniels -- and found that they were suffering from gastrointestinal disorders, including eosinophilic and lymphoplasmacytic infiltration of the stomach and small bowel, delayed gastric emptying, and gastroeosophageal reflux. In this study, the researchers treated the gastrointestinal (GI) diseases and observed complete resolution of the fly-biting in five of six of the seven dogs, including a cavalier. The seventh dog, the other CKCS, was diagnosed with Chiari-like malformation and responded temporarily to pain management. The researchers concluded that:
"Fly biting behaviour may be caused by an underlying medical disorder, GI disease being the most common. Resolution of this behaviour is possible following specific treatment of the underlying medical condition."
In a July 2015 article, Japanese researchers report finding that a fly-biting cavalier had a case of porencephaly, a congenital cerebral cavity, filled with cerebrospinal fluid (CSF), which is considered very rare in dogs. The dog exhibited symptoms of chewing and excitement before secondary generalized seizures and fly-biting after the seizures for 5–6 min.
Initially, treatment for epilepsy, such as administering an anti-convulsant (usually oral phenobarbital and/or bromide) usually is conducted. See Epilepsy for a discussion of the treatment of epileptic seizures in CKCSs.
However, it reportedly often has been found that CKCSs with flycatcher's syndrome will show no response to the anticonvulsant treatment, which would indicate the cause may be a compulsive disorder. In such cases, selective serotonin reuptake inhibitors (SSRIs), such as fluoxetine (Prozac, Sarafem), may be prescribed.
Clomipramine (Anafranil), a tricyclic antidepressant (TCA), inhibits both norepinephrine and serotonin reuptake. In a November 2010 Belgium study, it successfully treated a shadow-chasing cavalier. It has been suggested to have been associated with the onset of pancreatitis in one instance. See this February 2009 report.
CAUTION: Fluoxetine and other SSRIs, as well as clomipramine and other TCAs, can lead to serotonin accumulation and serotonin syndrome (symptomatically, twitching, tremor, tachycardia, myoclonic movements, and hyperthermia) in humans when used in combination with monoamine oxidase inhibitors (MAOIs, which decrease the breakdown of serotonin) or serotonin reuptake inhibitors, which increase synaptic serotonin concentrations. Deaths have been reported in humans given clomipramine plus MAOIs—a well-established interaction. See this June 2013 report. Also, high levels of serotonin in cavaliers' blood platelets and mitral valve tissues have been associated with mitral valve disease. For more information, see this discussion on our MVD webpage.
If phenobarbital and clomipramine are combined, phenobarbital accelerates the metabolism of clomipramine. See this June 2013 report.
Zonisamide (Zonegram) is an anticonvulsant which in clinical trials appears to be effective for generalized seizures in dogs. It’s anti-seizure effect is believed to work through sodium and calcium channels. Dr. Curtis Dewey has conducted studies of this drug.
Reconcile (fluoxetine hydrochloride) is FDA-approved for canine separation anxiety and also may be prescribed. However, Reconcile should not be given to dogs with epilepsy or a history of seizures, or with drugs that lower the seizure threshold, or with a monoamine oxidase inhibitor (MAOI), or within a minimum of 14 days of discontinuing therapy with an MAOI.
Daily doses of drugs may take three weeks or longer before a favorable effect is reached. The examining specialist may recommend that the dog be treated by a veterinary behaviorist to manage the compulsive disorder by behavior modification, such as counter-conditioning and positive reinforcement. Also, it is reported that high protein diets tend to worsen compulsive disorders, although the reduction of meat or other protein content may result in only temporary improvement.
Natural supplements may be prescribed as alternatives to anticonvulsants.
In a November 2012 study, a team of Canadian researchers studied seven fly-biting dogs, including two cavaliers, and found that they were suffering from gastrointestinal disorders, including eosinophilic and lymphoplasmacytic infiltration of the stomach and small bowel, delayed gastric emptying, and gastroeosophageal reflux. In this study, the researchers treated the gastrointestinal (GI) diseases and observed complete resolution of the fly-biting in five (including a cavalier) of six of the seven dogs. The seventh dog (the other cavalier) was diagnosed with Chiari-like malformation and responded temporarily to pain management. The researchers concluded that:
"Fly biting behaviour may be caused by an underlying medical disorder, GI disease being the most common. Resolution of this behaviour is possible following specific treatment of the underlying medical condition."
The Canine Inherited Disorders Database recommends that cavaliers which have had seizures should not be bred, nor should their parents and siblings.
August 2015: Japanese researchers find porencephaly in a fly-biting cavalier King Charles spaniel. In a July 2015 article, a team of Japanese veterinary researchers (Ai Hori, Kiwamu Hanazono, Kenjirou Miyoshi, Tetsuya Nakade) report discovering porencephaly -- a congenital cerebral cavity, filled with cerebrospinal fluid (CSF) -- in a 9 month old female cavalier King Charles spaniel. The dog exhibited symptoms of chewing and excitement before secondary generalized seizures and fly-biting after the seizures for 5–6 min. They examined a total of two affected dogs and one affected cat. Their aim of the study was to find if there was any hippocampal atrophy in cases of porencephaly, and they found in all three cases, less hippocampal volume or hippocampal loss at the lesion side or the larger defect side. They also noted that the severity of seizure symptoms was attributed to cyst ratio and asymmetric ratio. Both the cyst ratio and asymmetric ratio had correlation with the seizure symptoms. They concluded that porencephaly may coexist with hippocampal atrophy, and that clinicians should evaluate carefully the hippocampal volume and asymmetry in MRI, because the atrophy may have relationships with porencephaly-related seizures.
"Many gastrointestinal disorders were found in FB [fly-biting] dogs which included eosinophilic and lymphoplasmacytic infiltration of the stomach and small bowel, delayed gastric emptying and gastroeosophageal reflux. Complete resolution of the FB was observed in 5/6 dogs diagnosed and specifically treated for the underlying gastrointestinal (GI) disease. One dog was diagnosed with Chiari malformation and responded temporarily to pain management. In conclusion, this prospective case series indicates that fly biting behaviour may be caused by an underlying medical disorder, GI disease being the most common. Resolution of this behaviour is possible following specific treatment of the underlying medical condition."
Two of the studied dogs were cavaliers, including the dog diagnosed with Chiari-like malformation and one of the five dogs diagnosed and successfully treated for GI disease.
September 2009: Management of Compulsive Disorders. Dr. Clare Rusbridge and veterinary behaviorists Jon Bowen and Sarah Heath are conducting a study of fly catching, tail chasing, shadow watching, and other compulsive disorders to determine better management strategies. If you have a dog with a repetitive behavior disorder and able to fill out a questionnaire or provide urine or saliva samples, please contact Dr. Rusbridge at email CRusbridge@goddardvetgroup.co.uk
“Seizure-convulsions” (DeLahunta A.) in: Veterinary Neuroanatomy and Clinical Neurology, 2d ed., Editor DeLahunta A.;. W. B. Saunders (1983); pp 327.
Fly catching in the cavalier King Charles spaniel. Brown, P.R.. Vet. Rec. 1987, 120: 95.
Update on Mitral Valve Disease. Jens Häggström and Clarence Kvart. Proc. 15th ACVIM Forum; 1997. Quote: "An interesting observation that may be of comparative interest is that Cavalier King Charles Spaniels have been shown to have a high prevalence (30%) of thrombocytopenia and macrothrombocytosis. Humans with MVP [mitral valve prolapse] tend to have shortened platelet survival times and thromboembolic episodes primarily in the retinal and cerebral circulation. Thromboembolic events in the retinal ore cerebral circulation may be involved in the disturbances described in the breed as 'episodic falling' and 'fly catching'."
Control of Canine Genetic Diseases. Padgett, G.A., Howell Book House 1998, pp. 198-199, 235.
“Compulsive behaviour” (Luescher A. U.) in: BSAVA Manual of Canine and Feline Behavioural Medicine. Editors D. F. Horwitz D. F., Mills D. S., Heath S. Brit. Small Animal Vet. Assn., (2002); pp 229-236.
Neurological diseases of the Cavalier King Charles spaniel. Rusbridge, C. J Small Animal Practice, June 2005, 46(6): 265-272(8). "Fly catching has previously been classified as a complex partial seizure on the presumption that the dog was having an hallucination (DeLahunta 1983). However, it is more likely that this is a compulsive disorder (Luescher 2002). Classically, the dog acts as if watching, and then catching, a fly. Some may behave as if their ears or feet are irritated, and some may also chase their tail. In the author’s experience, the episodes can last hours and are more common, at least initially, when the owner’s focus is directed away from the dog; for example, when the family is watching television in the evening. In severe cases, the dog is occupied in the behaviour almost full time. Compulsive disorders are compared with obsessivecompulsive disorders in humans and are poorly understood; it is presumed that there is a neurochemical imbalance (Luescher 2002). Diagnosis is typically made on the basis of clinical history and elimination of other behavioural, medical and neurological disorders. Ideally the owner should make a video of the behaviour. If there is doubt as to whether it is epilepsy then a two- to four-week trial of 3 mg/kg phenobarbital every 12 hours is recommended, adjusting the dose to achieve a serum concentration of 25 mg/l (120 μmol/l). CKCSs with fly catching typically show no response (DeLahunta 1983). Referral to a veterinary behaviourist is recommended as there is often a learned component and treatment must involve behaviour modification in addition to drugs such as selective serotonin reuptake inhibitors; for example, 2 to 3 mg/kg clomipramine twice daily or 1 to 2 mg/kg fluoxetine twice daily. Management of compulsive disorders has been reviewed by Luescher (2002). In principle the behavioural therapy is to train the dog with positive reinforcement, rewarding it with attention or a small treat, to perform a desirable behaviour that is incompatible with the compulsive behaviour, such as lying with its head on the floor between the paws. As soon as the compulsive behaviour is seen then the dog is immediately distracted and instructed to perform the desirable behaviour. The reward can be progressively delayed so that the dog has to remain in the chosen position for increasingly longer times before the reward is given. If drugs are given then it can take four weeks before an effect is seen and they must be continued for at least three weeks after achieving the desired effect before attempting to withdraw them over a minimum of three weeks. High protein diets, such as those with high meat content, tend to make compulsive behaviours worse and conversion to a low protein diet can result in improvement in signs (Brown 1987), although in some dogs this may be only temporary."
Pancreatitis associated with clomipramine administration in a dog. P H Kook, A Kranjc, M Dennler, T M Glaus. J. Sm. Anim. Prac. Feb. 2009;50(2):95-98. Quote: "A three-year-old, male, entire, Yorkshire terrier was presented with peracute onset of abdominal pain and vomitus. Clinicopathological abnormalities included severely increased serum lipase activity, immeasurably high serum trypsin-like immunoreactivity and mild hypocalcaemia. Canine pancreatic lipase immunoreactivity (cPLI) was intended to be measured, however, the sample got lost. Ultrasonography revealed a hypoechoic pancreas with small amounts of peripancreatic fluid and hyperechogenic mesentery. Acute pancreatitis (AP) was diagnosed and the dog recovered with appropriate therapy within 48 hours. Clomipramine, a selective serotonin reuptake inhibitor (SSRI) for alleviating signs of separation anxiety had been given for seven weeks. Two similar, albeit less severe, episodes associated with previous courses of clomipramine had occurred eight months earlier that responded to discontinuing clomipramine and supportive care. As SSRIs are associated with AP in human beings and no other trigger could be identified, we conclude that clomipramine should be considered as a potential cause when investigating causes for AP in susceptible breeds or other dogs presenting with compatible clinical signs."
A Cavalier King Charles dog with shadow chasing: Clinical recovery and normalization of the dopamine transporter binding after clomipramine treatment. Simon Vermeire, Kurt Audenaert, Andre Dobbeleir, Eva Vandermeulen, Tim Waelbers, Kathelijne Peremans. J.Vet.Behavior: Clinical Applications & Research. Nov. 2010;5(6):345-349. Quote: "A 30-month-old female Cavalier King Charles dog was presented with a history of worsening compulsive behavior (shadow chasing). In vivo brain imaging using single-photon emission computed tomography and the dopamine transporter (DAT)-specific radiopharmaceutical 123I-FP-CIT revealed a significantly higher DAT striatal-to-brain ratio. Treatment was started with the tricyclic antidepressant clomipramine 2.5 mg/kg PO, q. 12 hours. After 2 months of medication that resulted in clinical improvement, the DAT binding regained normal values."
Breed Predispositions to Disease in Dogs & Cats (2d Ed.). Alex Gough, Alison Thomas. 2010; Blackwell Publ. 52.
Serotonin 2A receptor, serotonin transporter and dopamine transporter alterations in dogs with compulsive behaviour as a promising model for human obsessive-compulsive disorder. Simon Vermeire, Kurt Audenaert, Rudy De Meester, Eva Vandermeulen, Tim Waelbers, Bart De Spiegeleer, Jos Eersels, André Dobbeleir, Kathelijne Peremans. Psychiatry Research: Neuroimaging, online 27 Jan 2012. Quote: "Neuro-imaging studies have shown altered, yet often inconsistent, serotonergic and dopaminergic neurotransmission in patients with obsessive–compulsive disorder (OCD). We investigated both serotonergic and dopaminergic neurotransmission in 9 drug-naïve dogs with compulsive behaviour, as a potential model for human OCD. Single photon emission computed tomography was used with 123I-R91150 and 123I-FP-CIT, in combination with 99mTc-ECD brain perfusion co-registration, to measure the serotonin (5-HT) 2A receptor, dopamine transporter (DAT) and serotonin transporter (SERT) availability. Fifteen normally behaving dogs were used as reference group. Significantly lower 5-HT2A receptor radioligand availability in frontal and temporal cortices (bilateral) was observed. Further, in 78% of the compulsive dogs abnormal DAT ratios in left and right striatum were demonstrated. Interestingly, both increased and decreased DAT ratios were observed. Finally, significantly lower subcortical perfusion and (hypo)thalamic SERT availability were observed in the compulsive dogs. This study provides evidence for imbalanced serotonergic and dopaminergic pathways in the pathophysiology of compulsions in dogs. The similarities with the altered neurotransmission in human OCD provide construct validity for this non-induced, natural canine model, suggesting its usefulness for future investigations of the pathophysiology of human OCD as well as the effectiveness of psychopharmacological interventions."
Gastrointestinal disorders in dogs with excessive licking of surfaces. Becuwe-Bonnet V, Belanger M-C, Frank D, Parent J, Helie P. J.Vet.Behavior. July 2012;7(4):194-204. Quote: "Excessive licking of surfaces (ELS) refers to licking of objects and surfaces in excess of duration, frequency, or intensity as compared with that required for exploration. This behavior is a nonspecific sign and may be the consequence of several conditions. The objectives of our prospective clinical study were to characterize ELS behavior in dogs and to examine the extent to which it may be a sign of an underlying gastrointestinal (GI) pathology as opposed to a primarily behavioral concern. Nineteen dogs presented with ELS were included in the licking group and 10 healthy dogs were assigned to a control group. Behavioral, physical, and neurological examinations were performed before a complete evaluation of the GI system. Treatment was recommended on the basis of diagnostic findings. Following initialization of treatment, dogs were then monitored for 90 days during which their licking behavior was recorded. GI abnormalities were identified in 14 of 19 dogs in the licking group. These abnormalities included eosinophilic and/or lymphoplasmacytic infiltration of the GI tract, delayed gastric emptying, irritable bowel syndrome, chronic pancreatitis, gastric foreign body, and giardiasis. Significant improvement in both frequency and duration of the basal ELS behavior was observed in 10 of 17 dogs (59%). Resolution of ELS occurred in 9 of 17 dogs (53%). Based on video analysis, it was found that ELS dogs were not significantly more anxious than the dogs in control group in the veterinary context. In conclusion, GI disorders should be considered in the differential diagnosis of canine ELS."
Prospective Medical Evaluation of 7 Dogs Presented with Fly Biting. D. Frank, MC Bélanger, V. Bécuwe-Bonnet, J. Parent. 22nd ECVIM-CA Congress. Can Vet J. 2012 December;53(12):1279–1284. (See, also, J.Vet.Intern.Med. Nov. 2012; 26(6):1505–1538.) Quote: "Fly snapping, fly-biting or jaw snapping are names given to a syndrome in which dogs appear to be watching something then suddenly leaping and snapping at it. Fly-biting dogs are generally referred to neurologists or behaviourists because the abnormalities are often interpreted as focal seizures or as obsessive compulsive disorder (OCD). There is one published case report of fly biting presumably caused by dietary intolerance in a Cavalier King Charles Spaniel. The aims of this case series were 1) to characterize fly biting, 2) perform a complete medical evaluation of dogs presented with fly biting, and 3) evaluate the outcome of this behaviour following appropriate treatment of the underlying medical condition.Seven dogs presented for fly-biting behaviour (FB) were assessed. ... Our study group included 4 neutered males and 3 females (2 intact, 1 spayed). Four breeds (2 cavalier King Charles spaniels; 1 miniature schnauzer; 1 Boston terrier; 1 Bernese mountain dog), and 2 mixed breeds, both listed as crosses of Bernese mountain dogs were presented. ... All dogs underwent a complete medical and behavioural history as well as physical and neurological examinations. Further investigation was performed if an abnormality was found on examination or if the history was suggestive of an underlying problem. Based on clinical presentation, physical examination, neurologic examination, and laboratory test results, a diagnosis was made and a specific treatment recommended. Response to treatment was monitored and evaluated following phone conversations with owners at day 30, 60 and 90 from onset of treatment. Many gastrointestinal disorders were found in FB dogs which included eosinophilic and lymphoplasmacytic infiltration of the stomach and small bowel, delayed gastric emptying and gastroeosophageal reflux. Complete resolution of the FB was observed in 5/6 dogs diagnosed and specifically treated for the underlying gastrointestinal (GI) disease [including one cavalier King Charles spaniel]. One dog [cavalier King Charles spaniel] was diagnosed with Chiari malformation and responded temporarily to pain management. In conclusion, this prospective case series indicates that fly biting behaviour may be caused by an underlying medical disorder, GI disease being the most common. Resolution of this behaviour is possible following specific treatment of the underlying medical condition."
Drug Interactions in Polypharmacy. Lauren A. Trepanier. Clinician's Brief. June 2013:23-26.
Porencephaly in dogs and cats: relationships between magnetic resonance imaging (MRI) features and hippocampal atrophy. Ai Hori, Kiwamu Hanazono, Kenjirou Miyoshi, Tetsuya Nakade. J. Vet. Med. Sci. July 2015;77(7):889–892. Quote: "Porencephaly is the congenital cerebral defect and a rare malformation and described few MRI reports in veterinary medicine. MRI features of porencephaly are recognized the coexistence with the unilateral/bilateral hippocampal atrophy, caused by the seizure symptoms in human medicine. ... [T]he purpose of this study was to characterize the clinical signs and MRI features of porencephaly in dogs and cats, and to discuss the associated MRI with hippocampal atrophy. ... We studied 2 dogs [including one cavalier King Charles spaniel -- 9 month old female] and 1 cat with congenital porencephaly to characterize the clinical signs and MRI, and to discuss the associated MRI with hippocampal atrophy. The main clinical sign was the seizure symptoms, and all had hippocampal atrophy at the lesion side or the larger defect side. ... [CKCS] seizure symptoms: Secondary generalized seizures; neurological findings: Chewing, excitement, fly-biting. ... [CKCS] had abnormal behavior, such as chewing and excitement, before generalized seizures, and the dog showed 'fly-biting' after the seizures for 5–6 min. ... All cases had the less hippocampal volume or hippocampal loss at the lesion side or the larger defect side. Furthermore, the severity of seizure symptoms was attributed to cyst ratio and asymmetric ratio. ... [B]oth cyst ratio and asymmetric ratio had correlation with the seizure symptoms in this study. ... In conclusion, it is suggest that porencephaly coexists with the hippocampal atrophy as well as humans. We should evaluate carefully the hippocampal volume and asymmetry in MRI, because the atrophy may have relationships with porencephaly-related seizures."