Sacrocaudal Dysgenesis


Some animals are born with malformations in their spine associated with the lack of a tail, a trait specifically selected for in certain breeds. The most common malformations related to this tail-less trait include hemivertebrae, spina bifida, sacrocaudal agenesis and sacrocaudal dysgenesis.

In the case of sacrocaudal dysgenesis (literally, the term means malformation of the sacrocaudal vertebrae), the congenital abnormality results in a truncated spine, as happens in the Manx breed of cats.

Though only rarely, this abnormality can be associated with neurological defects. Innervation of the anus, urinary bladder, hind limbs and tail can be affected, leading to potentially life-threatening lifelong incontinence.

Symptoms and Identification

Dogs and cats normally show no ill effects related to this defect. Those who suffer neurologic deficits, however, will present very early on in life (within the first few weeks) with difficulty walking in the hind limbs and/or incontinence of feces or urine or both.

It is sometimes associated with spina bifida, particularly in the case of Manx cats.

Diagnosing sacrocaudal dysgenesis happens typically via signalment and symptoms. Though imaging (usually with X-rays but also with a myelogram, CT scan and/or MRI) is recommended, most neurologically affected puppies and kittens are simply euthanized.

Affected Breeds

The most commonly affected breed of companion animal is the Manx cat. Affected dogs include the tail-less, such as certain breeds of Bulldogs (most notably the English variety) and Old English Sheepdogs.


There is no known treatment for this congenital disease. It is possible, however, to adapt affected animals to carts that will allow for ambulation in the case of severe paraplegia. Any related incontinence, however, is not considered treatable and is the most common cause for euthanasia related to sacrocaudal dysgenesis.

Veterinary Cost

The cost of treatment depends on the lengths an owner will go to in accommodating a neurologically abnormal animal to life in a paraplegic’s cart or other approach. Diagnosis is typically very inexpensive unless major imaging work is performed.


Curbing the breeding of any first degree relatives to affected animals is a must. Parents and siblings should not be bred. Ideally, animals should not be bred for tail-lessness. This trait is fraught with unintended spinal consequences as mentioned above.


Braund, K.G. (2003). "Developmental Disorders". Clinical Neurology in Small Animals: Localization, Diagnosis and Treatment. Retrieved 2007-02-04.

^ a b "Congenital and Inherited Anomalies of the Nervous System: Small Animals". The Merck Veterinary Manual. 2006. Retrieved 2007-02-04.

Canine Inherited Disorders Database