Until recently, no medications appeared to remedy the condition, and there was no known effective treatment. However, in a study concluded in 2003, a group of affected Cavaliers was treated with Clonazepam, a drug used to treat humans for hereditary hyperekplexia ("startle disease"). With treatment, the episodes decreased in frequency from between 25 and 30 per week to as few as one every two to three months. After two years of treatment with Clonazepam, dogs in the study were described as clinically normal.
However, in a study currently being conducted by Dr Jacques Penderis, senior research neurologist at the Animal Health Trust in the UK, he has found that although some Cavaliers initially respond well to treatment with Clonazepam or Diazepam, the dogs tend to develop tolerance to the drugs after a while and the beneficial effect wears off. Dr. Penderis states that the current treatment options for CKCSs with episodic falling syndrome are extremely limited.
The Animal Health Trust is conducting research to try to establish the pattern of inheritance of episodic falling in the Cavalier. It is collecting pedigrees from affected dogs for pedigree analysis, particularly where the disease status of related dogs (e.g. parents and litter mates) are known.
In an attempt to develop a more effective treatment for dogs that are severely affected, Dr. Penderis is conducting a trial of some other drugs that have been shown to be beneficial in human patients and to which the Cavaliers' tolerance does not develop. He advises that the initial results for one drug have so far been promising. The current trials are restricted to those dogs that have very frequent collapse episodes and are arranged through the owners' veterinarians.
Dr. Penderis also is collecting blood samples for DNA extraction to conduct genetic linkage analysis in order to determine the offending gene. In order to perform genetic linkage analysis, Dr. Penderis requires blood samples from known affected dogs and from as many normal related dogs as possible (particularly litter mates, parents, grandparents and offspring). The study's goal is to develop a genetic test to allow identification of the affected dogs and asymptomatic carriers, so that the disease may be totally eradicated from all tested breeding lines.
In order to reduce the incidence of the disease and eventually develop a genetic test, Dr. Penderis is interested in information from as many affected dogs as possible from the Cavalier King Charles Spaniel breed. He states that what is essential to the research is that no dogs that do not have episodic falling syndrome are inadvertently included in the study (e.g. have similar appearing stiffness or collapse episodes that are not due to episodic falling) as this could severely hamper the genetic analysis. The disease will therefore need to be confirmed by video footage of an episode or examination of the dog at the Animal Health Trust. Please contact Dr Jacques Penderis at the Animal Health Trust if you wish to participate in the research project. He may be reached at Animal Health Trust, Lanwades Park, Kentford, Newmarket, CB8 7UU, UK. Telephone: (+44) (0)1638 552700; Fax: (+44) (0)1638 555600; email: Jacques.Penderis@aht.org.uk