Manx Syndrome

Implications of the short tail mutation in Manx cats


  • Originates from Isle of Man (UK)
  • It's thought they tail-less trait originated here because of the island isolation
  • Believed to be caused by bad breeding techniques
  • Manx cats have been bred on the island or exported and bred with other Manx cats from the Isle of Man
  • Popular in the UK and the USA, with only a small amount in Australia

What is Manx Syndrome?

  • Manx Syndrome is a genetic disease in the Manx breed that causes deformation in the spinal cord that leads to a shortening of the tail
  • Mutation causes the trait that results in a variation of an absence of tail to a slightly shortened tail
  • This deformity is almost always considered spina bifida, which is a midline cleft in the vertebral arch in one or a few vertebra

Implications of Manx Syndrome

  • Some cats with Manx Syndrome have little or no symptoms but the vertebrae are always abnormal
  • It is common for the cat to have one or more complications including, neurological diseases, nervous system diseases, incontinence, lack of feeling in back legs, severe sensitivity of the spinal cord, and trouble walking.
  • Cats with these symptoms are usually fated for an early death or will have a hard time being placed with a family that can care for it
  • Some of the spinal defects seen are:
  • Spina bifida: Failure of the spinal vertebral arch(es) to close over the spinal cord
  • Meningocele (MC): Protrusion of meninges through open vertebral arch or cranial bones
  • Meningomyelocele (MMC): Protrusion of meninges and nervous tissue through open vertebral arch
Spina Bifida kitten Timmy

Inheritance of this disease

  • Manx syndrome is an autosomal dominant genetic disease
  • Gene responsible for Manx syndrome is dominant (M) but cats with Manx syndrome are heterozygous dominant (MML) because it is thought that the homozygous dominant gene (MM) is lethal.
  • Cats that are homozygous recessive (MLML) will have long tails

Genotype and Phenotype of Manx Syndrome

  • As shown in the punnett square below:
  • Two cats bred with Manx Syndrome (heterozygous MML) create a 1:2:1 genotypic ratio of 1/4 (25%) probability of homozygous dominant for the lethal Manx gene (MM) and 2/4 (50%) probability of heterozygous dominant for the Manx gene, and 1/4 (25%) probability for normal spine (homozygous recessive MLML)
  • A cat with Manx Syndrome (heterozygous dominant) bred with a normal cat (homozygous recessive) would result in a 50% probability of Manx Syndrome offspring (heterozygous dominant) and 50% probability of normal cat offspring.
  • The phenotype for Manx Syndrome is variable as shown in the pictures below
  • Even when the phenotype for Manx Syndrome is minimal (i.e. a longer tail) the spine is still abnormal. Stumpies and Longies have normal looking tails but they can still have spinal defects, such as spina bifida.
Big image


  • Manx Syndrome is not widely recognized as a disease by many veterinarians
  • There is currently no method for eradicating Manx Syndrome
  • The Manx cat can still be bred and bought as a cat breed for show or as a household pet
  • Breeders still select for the "Rumpy" style with no tail


  • Manx Syndrome is a genetic disease that has come about from bad breeding techniques. The implications of the disease can be devastating for the cat and even lethal. The quality of life is often very poor as it can cause pain and make natural abilities for the cat difficult. For example, cats rely on their tails for balance and in communicating with each other. Manx Syndrome also causes many health problems, which range from debilitating to causing health/mobility complications. This trait is only selected for because many people think the shorter tail is an attractive quality. The health implications of this disease are life threatening and actions should be taken by cat breed associations as well as veterinarians to learn more about this syndrome and to eradicate this disease.


1. Deforest, M. E., & Basrur, P. K. (1979). Malformations and the Manx Syndrome in Cats. The Canadian Veterinary Journal, 20(11), 304-314. Retrieved April 19, 2016, from

2. Manx Syndrome and Spina Bifida. (2015). Retrieved April 17, 2016, from

3. Martin, A. H. (1971). A Congenital Defect in the Spinal Cord of the Manx Cat. Veterinary Pathology, 8(3), 232-238. Retrieved April 19, 2016, from

4. Song, R. B., Glass, E. N., & Kent, M. (2016). Spina Bifida, Meningomyelocele, and Meningocele. Veterinary Clinics of North America: Small Animal Practice, 46(2), 327-345. doi:10.1016/j.cvsm.2015.10.007

5. What Is Manx Syndrome? (2015). Retrieved April 17, 2016, from