Flycatcher's Syndrome in
Cavalier King Charles Spaniels
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. Symptoms
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. 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.
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.
Diagnosis
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.
Treatment
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 anti-convulsant treatment, which would indicate the cause may be a compulsive disorder. In such cases, selective serotonin reuptake inhibitors, such as clomipramine or fluxetine, may be prescribed.
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 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.
Breeders' Responsibilities
The Canine Inherited Disorders Database (www.upei.ca/~cidd/intro.htm) recommends that Cavaliers which have had seizures should not be bred, nor should their parents and siblings.
Current Research
4September 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
Related Link
Veterinary Resources
“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).
