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Devon Rex and Sphynx “Spasticity”
Lead Contact: Leslie Lyons – firstname.lastname@example.org
‘Spasticity’ as it is known to breeders, refers to a congenital myopathy somewhat similar to some types of human muscular dystrophy. Affected cats usually show obvious signs of a locomotor problem when six to 20 weeks of age. Muscle weakness is the key feature, with prominent downward flexion of the head and neck, protrusion of the scapulae, head bobbing, and swallowing difficulties. These signs are often first noted when the cat is using the litter tray. Some cats compensate for the neck muscle weakness by adopting a Meer cat like posture, also known as periscoping.
Affected cats have a generally unsatisfactory quality of life and are at risk of sudden death due to obstruction of the throat with food. Studies have shown the underlying problem to be a primary muscle disorder (sarcoglycanopathy), although the molecular basis of the condition has not yet been determined.
‘Spasticity’ is so characteristic in its clinical manifestations that breeders have become adept at identifying affected individuals before kittens reach an age when they are sold and rehoused. The benefit of this is that it is most unlikely that an affected kitten will ever be sold as a pet. The disadvantage is that affected kittens may still be being produced, and subjected to euthanasia without the problem of eliminating the defective genes ever being addressed.
Note downward flexion of the head and neck
Periscoping is illustrated on the left, whereas ventral neck flexion and protrusion of the shouders is shown on the right
A recessive mutation that causes a congenital muscle weakness, “myopathy” in Devon rex and Sphynx cats has been discovered by a world-wide research team of geneticists and neurologists from the University of Missouri, the University of California – Davis, the University of California -San Diego, the University of Sydney and the University of Milan. The mutation affects a gene, COLQ, which causes a congenital myasthenic syndrome (CMS) that is similar to humans.
Affected cats present with passive ventroflexion of the head and neck, head bobbing, scapulae protrusion, megaesopahagus, generalized muscle weakness and fatigability. The disease likely started in Devon Rex and spread to Sphynx. Cats show prominent lordosis and generally succumb to the disease by asphyxiation due to choking on food or aspiration pneumonia by two years of age. Signs became evident at three to 23 weeks of age and then usually progressed slowly or remained static. Cats must have 2 copies of the mutation to have disease.
Moderately to severely affected cats show evidence of more generalized muscle weakness, particularly following exertion, stress or excitement. Typically they have a high-stepping forelimb gait, head bobbing and progressive dorsal protrusion of the scapulae. Affected cats tire easily with exercise, with progressive shortening of the stride and superimposed tremor. Eventually they collapse in sternal recumbency, typically with the head coming to rest on, or to one side of, their front paws. Affected cats frequently adopt a characteristic ‘dog-begging’ or “chipmunk” position, usually with their front legs resting on a convenient object.
The disease was first described in the UK in 1989 with detailed presentations from Australia in 1993. Cats have been identified in the USA and more recently across Europe.
We appreciate the assistance of Nicholas Gustafson, the strong and long-standing dedication of cat breeders Sybil Drummond and Pam Dowlings, Paolo Valiati, and the Italian Feline Biobank-Vetogene.
Funding was provided by the National Center for Research Resources R24 RR016094 and is currently supported by the Office of Research Infrastructure Programs/OD R24OD010928, the University of Missouri – Columbia Gilbreath-McLorn Endowment, the Winn Feline Foundation (W10 -014 , W11-041, MT13-010), the Phyllis and George Miller Trust (MT08-015), the University of California – Davis, Center for Companion Animal Health (2008-36-F, 2008-06-F) and the Cat Health Network (D12FE-510) (LAL). Richard Malik is supported by the Valentine Charlton Bequest.
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