Corneal dystrophy (r)
An unusual and rarecorneal dystrophy has been described in the Manx breed, characterised by bilateral corneal oedema (cloudiness of the usually clear front of the eye) developing from around 4 months of age. The condition is progressive, leading to bullae formation within the corneal stroma.
Bistner SI, Aguirre G, Shively JN (1976). Hereditary corneal dystrophym in the Manx cat: A preliminary Report. Investigative Ophthalmology and Visual Sciences 15: 15-26
Manx Syndrome: sacrocaudal dysgenesis, megacolon and constipation, rectal prolapse, congenital urinary tract defects, and spina bifida (*)
The Manx breed has a naturally occurring mutation of the spine. This mutation shortens the tail, resulting in a range of tail lengths from normal to tailless:
- Dimple rumpy or rumpy - no tail whatsoever
- Riser or rumpy riser - stub of cartilage or several vertebrae under the fur, most noticeable when kitten is happy and raising its 'tail'
- Stumpy - partial tail, more than a 'riser' but less than 'tailed' (in rare cases kittens are born with kinked tails because of incomplete growth of the tail during development)
- Tailed or longy - complete or near complete tail
Breeders have reported all tail lengths even within the same litter. The taillessness arises from a genetic mutation that is autosomal dominant and highly penetrant. Having two copies of the gene is lethal and kittens are usually spontaneously aborted before birth. This means that tailless cats can carry only one copy of the gene. Because of the danger of having two copies of the tailess gene, breeders have to be careful about breeding two tailess Manxes together. Problems can be avoided by breeding tailess cats with tailed ones and this breeding practice is responsible for the decreasing occurrence of spinal problems in recent years.
Manx Syndrome is the name given to the condition which results when the mutant tailless gene shortens the spine too much. It can seriously damage the spinal cord and the nerves causing spina bifida as well as problems with the bowels, bladder, and digestion. (In addition, cats with partial tails are prone to arthritis of the tail and this can cause severe pain). In one study Manx syndrome was shown to affect about 20% of Manx cats, and almost all of those cases were rumpies. Thankfully, occurrence is now less common due to more informed breeding practices. In addition, most pedigree cats are not allowed to leave the breeder until 3-4 months of age (to make sure that they are properly socialised and vaccinated) and this gives adequate time for any health problems to be identified.
Robinson R (1993) Expressivity of the Manx Gene in Cats. Journal of Heredity 84,170-172,
Todd N B (1964) The inheritance of taillessness of Manx cats. Journal of Cat Genetics 1, 2-7
Howell J M & Siegel P B (1963) Phenotypic variability of taillessness in Manx cats. Journal of Heredity 54,167-169
Deforest M E & Basrur P C (1979) Malformations and the Manx syndrome in cats. Canadian Veterinary Journal 20, 304 – 314
Liepold H W et al (1974) Congenital defects of the caudal vertebral column and spinal cord in Manx cats. Journal of the American Veterinary Medical Association 164, 520 – 523