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EPISODIC FALLING IN CAVALIER KING CHARLES SPANIELS
CURRENT AND PAST RESEARCH
On this page you will find information about:
Falling ('Hypertonicity') in the Cavalier
 King Charles Spaniel
Dr Jacques Penderis BVSc MVM PhD
CertVR DipE CVN MRCVS ©
RCVS and European Specialist in Veterinary Neurology
Animal Health Trust, Lanwades Park, Kentford,
Newmarket, CB8 7UU, UK
Research into Episodic Falling has been done at The Animal Health Trust in the UK, led by Dr. Jacques Penderis, a leading neurologist.
This research is being continued by Dr. Penderis at the University of Glasgow.
A brief summary of Dr. Penderis' work on Episodic Falling and a reference list is available at the link below:
http://www.aht.org.uk/sci_randd_neurologymov.html
Test Breeding Program for Episodic Falling, 1995 to present
Christa Krey
(note: a simple paper on recessive genetics is available from Dorothie Hellman. Please see the contact page)
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Spicy, Christa Krey's Episodic Falling affected Cavalier
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Introduction
The problem of Episodic Falling in the King Charles Spaniel has been spreading. There are many reasons for the increase in the incidence of this disorder, including a lack of awareness of Episodic Falling itself, and a lack of understanding of how the disorder is spread.
Episodic Falling is a heartbreaking syndrome and it is not a benign disorder. We are unsure of the level of pain, but it appears that chronic pain can be exsisting even when the dog is not having epidodes. EF can be as devastating as Syringomyelia or mitral valve disorder to the people who own severely affected Cavaliers. People who purchase puppies with episodic falling are often scared and always disappointed.
Episodic Falling is a syndrome of paroxysmal hypertonicity. During an EF episode the dog's muscles become rigid (hypertonicity) although he retains consciousness. In severe cases, the front legs curl up over the head, rear legs become rigid through the toes. The jaws are clenched. If not stopped, it is likely that the affected dog will try to rise and fall. The dog's quality of life can be significantly affected since, in severe cases, episodes can last for hours and can happen many times a day. Episodic Falling has been known to be fatal in the event that the episode cannot be stopped.
In my experience, symptoms almost always arise before 5 months although signs may be missed. Veterinarians very often are not aware of the disorder and sometimes owners end up spending thousands of dollars to discover what is affecting their puppies without an outcome that is meaningful. However, Episodic Falling can be diagnosed by a videotape or the description of symptoms with a knowledgeable veterinarian.
Research is underway at the University of Glasgow by Dr. Jacques Penderis to find the gene responsible for Episodic Falling. Until the gene is identified, test breeding is the only way to determine the mode of inheritance for EF.
If episodic falling can be traced to a recessive gene, then responsible breeders can contribute to the eradication of the disorder by ceasing to breed their Cavaliers who are carriers. Unfortunately, until people understand that episodic falling is a recessive gene, they erroneously believe that they can continue to breed a dog or bitch that has produced even one puppy with episodic falling. Because of the nature of recessive genes, until we find a way to test for the responsible gene, there is no way of knowing whether the grandsire or granddam was the carrier if one of their offspring's breedings results in a puppy with episodic falling.
The Mendelian Mode of Inheritance
A recessive gene can easily hide for generations. If one parent is a carrier, we would expect to find half of the puppies to be carriers, but not affected by episodic falling (table 1). If both parents were carriers, we would expect to find 25% affected, 25% clear of the disorder, and 50% carriers (Table 2). If one affected parent is bread to one carrier, we would find 50% affected and 50% carriers(Table 3). In litters from carriers, while there will be some clear puppies there is no way at the present time to determine which puppies are clear and which are carriers as no symptoms are present.
TABLE 1: Carrier to non-carrier- 50% pups carriers
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Sire
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Clear
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Clear
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| Dam |
Carrier
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Carrier
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Carrier
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Clear
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Clear
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Clear
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TABLE 2: Carrier to carrier - 25% affected, 50% carriers
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Sire
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Carrier
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Clear
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| Dam |
Carrier
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Affected
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Carrier
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Clear
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Carrier
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Clear
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TABLE 3: Carrier to EF- 50% affected, 50% carriers
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Sire
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Carrier
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Carrier
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| Dam |
Carrier
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Affected
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Affected
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Clear
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Carrier
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Carrier
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Method
Thirty litters were bred from Cavaliers where one or both parents was known to be a carrier. No litters were bred from two affected cavaliers, as there is much evidence that the disorder is carried recessively, and I did not wish to produce litters where 100% of the pups have EF. Also 10 affected puppies were reported to the researcher, and pedigrees were traced to determine carrier dams and sires.
If the Mendelian principle of single recessive inheritance is applied to Episodic Falling Syndrome, then both parents of an affected pup must be carriers. In turn, one of each of the grandparents must be a carrier. Initially these two out of the four grandparents cannot be identified, however if many pedigrees of affected pups are compared, those dogs that show up repeatedly can then be assumed to be the carriers, and a line can be drawn backwards through the pedigrees.
For more information on mendelian genetics, please refer to either:
http://www.beaconforhealth.org/Genes-Bell.htm
http://www.phschool.com/science/biology_place/biocoach/inheritance/intro.html
In order to ameliorate the prevalence of EF in Cavaliers, except for those pups which were retained for test breeding, unaffected pups from these test litters were sold to good homes and were spayed or neutered. Affected puppies were placed in good homes, spayed or neutered and followed closely by myself, except for three puppies which were so severely affected that they were humanely euthanized.
Results
Thirty litters resulted in 123 Pups, 97 of which were followed up.
Twelve matings included litters where only one parent was known to be a carrier. Of the 54 pups produced by these litters, 16 or 30% turned out to be carriers. Only 16 pups were bred, so the exact percentage of carriers is unknown.
12 litters resulted from matings where both parents were known to be carriers. Of the 42 pups produced, 12 or 28.5% had EF.
Six litters were produced from matings where one parent was affected and one was a known carrier. Of the 27 pups, 20 were followed and ten are known to have EF or 50%.
The above results are all consistent with rates what would be expected given the Mendelian mode of inheritance.
Conclusion
Until pups are identified with EF, it is impossible to know whether or not either of the parents is a carrier. If both parents are carriers, the expectancy of a pup with the recessive gene is one in four.
My results support the Mendelian mode of inheritance for Episodic Falling in Cavalier King Charles Spaniels. Episodic Falling is easily identifiable and easily avoided if breeders cease to breed Cavaliers who produce EF pups, pups from litters where an EF pup is identified, and grandparents of EF pups. While it is tempting to breed a champion or a Cavalier with a good heart, I would argue that the breed can be greatly improved in a short time if we are willing to make some sacrifices in the short-term.
As EF affected or EF carriers are bred, the incidence of both carriers and affected puppies will grow until less than 25% of Cavaliers will be non-carriers given the Mendelian mode. However, since the use of stud dogs and dams is not random, if a popular sire or dam who is a carrier is used extensively, far fewer than 25% can remain non-carriers. In Scottish Terriers, some researchers believe that 90% of the population are carriers of another recessive disorder, "Scottie Cramp". The Cavalier breed must not come to this.
Only when a genetic test is available will it be safe to breed carriers with other desirable traits such as good hearts and eyes.
One of Christa Krey's Cavaliers got it's first diagnosis of EF in 1995. Since then she has tirelessly carried out a test breeding program in an attempt to determine the genetic nature of this disorder. Christa lives in Levin, New Zeland. For more information she can be reached at cavalier@paradise.net.nz.
LINKS
Web sites can change or close without warning. If you have difficulty with any of these links, please contact Dorothie Hellman so that she can update this site.
Amber's Story and research paper by M. E. Herrtage, A. C. Palmer
Amber is a six year old ruby bitch, owned by Mrs. Tina Whittaker of Tilalee Cavaliers in the UK. Amber is quite badly affected by EF but medication helps her to have a good quality of life. Tina has been trying to raise awareness of EF for the past six years. The paper by Dr A. C. Palmer and Dr. M.E. Herrtage was written nearly 30 years ago. A very eminent man, Dr Palmer was the first person to bring Episodic Falling to light at a veterinary congress in 1981.
http://website.lineone.net/~tilalee/health_act.htm
 Comparative Neuromuscular laboratory
Neuromuscular Case of the Month - JUNE 2001
Hypertonicity in Cavalier King Charles Spaniels
Contributed by G. Diane Shelton, DVM, Ph.D. Department of Pathology University of California, San Diego This web site has specific information related to the research of Dr. Diane Shelton. It contains a video of an affected puppy with less severe symptoms of falling and tumbling than the video included on this site. Dr. Shelton is still interested in hearing about dogs affected with EF but this must be done through your veterinarian. This restriction is only so that she can effectively continue her research. We appreciate your cooperation so that we can continue to link to her site.
http://medicine.ucsd.edu/vet_neuromuscular/cases/2001/jun01.html
Paroxysmal Disorders (6-feb-2003)
by K. G. Braund
In: Clinical Neurology in Small Animals -
Localization, Diagnosis and Treatment, K. G. Braund (Ed.)
Publisher: International Veterinary Information Service (www.ivis.org), Ithaca, New York, USA
This is a comprehensive review of all Paroxysmal Disorders including Episodic Falling. The section relevant to EF is on the first page.
http://www.ivis.org/special_books/Braund/braund29/ivis.pdf | 
