Chondrodystrophy (CDDY) is a common body shape in many breeds and is characterized by relatively shortened legs compared to body length.

Intervertebral discs connect vertebrae, allow spine movement and protect the spinal cord. The intervertebral disc is composed of an outer fibrous layer (annulus fibrosus) and an inner gel-like layer called the nucleus pulposus. In chondrodystrophic breeds, premature hardening of the soft center of the disc at an early age (from birth to one year of age) results in intervertebral disc degeneration (IVDD). This disc degeneration can lead to Type I IVDD which is characterized by rupture of the center of the disc through tears in the outer fibrous layer. Clinical signs result from the pressure applied to the spinal cord and nerves. 

Breed Predisposition

• Beagles
• Cavalier King Charles Spaniels
• Cocker Spaniels
• Pembroke Welsh Corgis & Cardigan Welsh Corgis
• Dachshunds
• French Bulldogs 
• Miniature Poodles 
• Pekingese 

• Others

Clinical signs

• Signs of CDDY are recognized in puppies as it affects their body shape.
• Type I IVDD is usually first recognized in young adult dogs, with breed-specific differences in age of onset.
  • Sudden or gradual onset of hind leg weakness (partial paralysis)
  • Knuckling (paw dragging)
  • Ataxia (loss of coordination)
  • Signs of neck or back pain (e.g., reluctance to jump or walk or to be pet or lifted; vocalization when moving; unusual aggression towards being touched; stiff neck or arched back) 

  • Paralysis 

Diagnosis       

• Clinical signs
• Physical examination
• Radiographs may show disc calcification and/or a decreased intervertebral disc space (indicating disc extrusion).
• Advanced imaging such as CT or MRI may show additional details.

Treatment

Early intervention provides the best outcome.

• Milder cases may be treated with rest and pain medications.
• More severe cases may warrant surgical intervention.
• Maintain an ideal body condition (weight).
• Modify activities to put less stress on the spine such as providing steps or ramps to reduce jumping on and off objects.
• Low-stress options such as front clip options may be recommended when a harness is used.
• Supplementation with omega fatty acids and/or glucosamine and chondroitin may offer some benefits, although no specific clinical trials have been performed.

Genetics

The Fibroblast growth factor 4 (FGF4) retrogene insertion on chromosome 12 may be responsible for a portion of cases of chondrodystrophy and increased risk for Type I IVDD in certain dog populations.

Dogs with one copy of this variant have modestly shortened legs, while dogs with two copies are more likely to have the characteristically short legs with a relatively long body. CDDY can be caused by other variants alone or in combination with this FGF4 retrogene.

The FGF4 retrogene also increases the risk of Type I Intervertebral Disc Disease (IVDD) in a dominant fashion. This means dogs with one or two copies of this variant are at an increased risk of developing this disease. While this variant is known to increase the risk of Type I IVDD, it does not explain all cases. There are other factors that contribute to the overall risk of developing Type I IVDD, including other (unknown) genetic variants, lifestyle and other environmental factors.

It is important to understand the frequency of this variant within certain populations is very high, because certain breed standards call for a chondrodystrophic (short legs, long body) appearance. When deciding whether or not to breed a dog with this variant, we recommend considering the whole dog (rather than this one test in isolation). Other factors to consider include:

• Have any relatives of this dog shown back, neck, or neurologic problems?
• Does this dog meet the breed standard?
• Has this dog passed its breed-required health testing?
• Does this dog have the desired temperament for the breed?
• Is this dog otherwise healthy?

If all other health and temperament parameters are desired, then breeding dogs with one or two copies of the variant to dogs with no copies is a first step towards reducing the high frequency of this variant within certain breeds. Among breeds in which the frequency of this variant is high, dogs with one or two copies of this variant should not be immediately removed from the breeding population. This practice can reduce the size of the breeding population substantially, leading to other health issues associated with inbreeding and reduced genetic diversity.

This health topic was developed as part of a collaboration between the Cornell Richard P. Riney Canine Health Center and Embark Veterinary, Inc. You can learn more about the hereditary risks of other canine health conditions by exploring our genetics articles.

Updated Aug. 2024