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Sacrocaudal dysgenesis

Sacrocaudal dysgenesis is a common neurological disease of Manx cats. This is a malformation involving the caudal part of the neural tube and associated sacrocaudal somites. As a rule there is agenesis of the caudal vertebrae and the caudal sacral vertebrae. Spina bifida often occurs in the remaining sacral vertebrae and occasionally the 7th lumbar vertebra. This vertebral column malformation is associated with various neural tube malformations that include a meningocele, meningomyelocele, sacrocaudal segmental agenesis, hypoplasia or dysplasia and syringohydromyelia[1].

Cause

This is an unfortunate genetic disorder developed by the breeders of Manx cats in order to obtain a breed lacking a tail. What is not known is how many kittens are born with such a severe agenesis of the lumbosacral spinal cord segments that they are unable to walk and are discarded shortly after birth. Tailless Manx cats is a malformation that is transmitted as an autosomal dominant trait[2]. This disease is also known as ‘caudal dysgenesis’ and exemplifies a malformation brought about by breeders selecting for tailless cats. The variable expression of Manx taillessness is a salient and consistent feature of the Manx syndrome[3].It is our obligation as veterinarians to inform these Man cat breeders that they are breeding for an abnormality that can be lethal to this breed and such action is inhumane and should cease. They should be advised to put the tail back on their Manx cats.

Clinical signs

Clinical signs of this syndrome in those kittens that can ambulate include taillessness, a “bunny hopping” gait in which both pelvic limbs are protracted simultaneously and urinary and fecal incontinence with megacolon. The meningocele or meningomyelocele may be large enough to cause a visible soft swelling over the remaining sacrum.

Treatment

Mildly affected animals may attain longevity if fecal and urinary incontinence are managed.[4]

Nutritional osteodystrophy and osteoporosis were suggested as the cause of acquired thoracic vertebral malformation in an immature Domestic shorthair cat, leading to lordosis and subarachnoid cyst formation. Congenital vertebral anomalies such as hemivertebrae and spina bifida are reported in Domestic shorthair kittens affected by mucolipidosis II. Similarly, Marioni-Henry found in her study that all the cats with congenital disease of the vertebral column were affected by mucopolysaccharidosis VI[5].

References

  1.  Newitt A et al (2008) Congenital abnormalities of the feline vertebral column. Vet Radiol Ultrasound 49(1):35-41
  2.  Kitchen H, Murray RE, Cockrell BY. (1972) Animal model for human disease. Spina bifida, sacral dysgenesis and myelocele. Animal model: Manx cats. Am J Pathol 68:203-206
  3.  Leipold HW, Huston K, Blauch B, et al (1974) Congenital defects in the caudal vertebral column and spinal cord in Manx cats. J Am Vet Med Assoc 164:520-523
  4.  Havlicek, M et al (2009) Surgical management of vertebral malformation in a Manx cat. JFMS 11:514-517
  5.  Marioni-Henry K et al (2004) Prevalence of disease of the spinal cord of cats. J. Vet Int Med 18:851-858

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