IVDD in Dachshunds and Chondrodystrophic Breeds: Genetics, Risk, and Testing

Intervertebral Disc Disease is the most common neurological disease in dogs, and in breeds like the Dachshund, it can strike at any age — causing sudden pain, paralysis, and the need for emergency surgery.

Intervertebral Disc Disease (IVDD) occurs when the cushioning discs between the vertebrae of the spine degenerate, bulge, or rupture and press on the spinal cord. The result ranges from mild pain to complete paralysis.

The Two Types of IVDD

Hansen Type I IVDD — The disc's interior material calcifies (hardens) and then explosively ruptures through the disc's outer layer, causing sudden spinal cord compression. This is the type associated with chondrodystrophic breeds and the CDDY mutation. Onset is often sudden and dramatic — a dog that was fine yesterday may be paralyzed tomorrow.

Hansen Type II IVDD — The disc bulges and protrudes gradually over time. Associated with larger, older dogs (German Shepherds, Labrador Retrievers, etc.). Slower onset.

The CDDY Mutation — Why Dachshunds Are Different

The short-legged, long-bodied phenotype of Dachshunds, Basset Hounds, Corgis, and other chondrodystrophic breeds is caused by the CDDY (Chondrodystrophy) mutation — a retrogene insertion on chromosome 18. This mutation causes cartilage to develop abnormally throughout the body, including in the intervertebral discs.

In CDDY dogs:

• Disc material begins calcifying as young as 12-18 months
• Calcified discs are rigid and prone to rupture
• Type I IVDD risk is dramatically elevated throughout life

CDDY is dominant — only ONE copy is needed to cause chondrodystrophy (and the associated short-leg conformation in some breeds). Most chondrodystrophic breeds are homozygous (two copies) for CDDY.

A newer, more severe mutation (IVDD Type I) has also been identified in some breeds that dramatically increases rupture risk independently of CDDY. Testing for this separate variant is now available.

Breeds at Highest Risk

Chondrodystrophic (CDDY/CDDY) breeds with high IVDD rates:

• Dachshund (25% lifetime risk — highest of all breeds)
• French Bulldog
• Basset Hound
• Shih Tzu
• Pekingese
• Beagle
• Lhasa Apso

Breeds with heterozygous CDDY at elevated risk:

• Labrador Retriever
• Golden Retriever
• American Cocker Spaniel

Radiographic Disc Screening

The most actionable IVDD risk reduction tool currently available to breeders is radiographic disc screening — X-rays that count how many discs have calcified.

The Danish Dachshund Protocol: Developed by researchers at the University of Copenhagen, this protocol uses X-rays at age 2 to count calcified discs:

• 0-1 calcified discs: Low risk — these dogs are preferred for breeding
• 2-3 calcified discs: Moderate risk — breed with caution
• 4+ calcified discs: High risk — should not be bred

Dogs with fewer disc calcifications are significantly less likely to develop clinical IVDD. This screening can meaningfully reduce IVDD prevalence across generations when used as a breeding selection criterion.

Availability: Any veterinarian can perform the X-rays; interpretation may require experience. The Danish protocol has been adopted by breed clubs in Scandinavia and is gaining adoption in the UK and US.

IVDD Type I Genetic Testing

A newer genetic test identifies dogs carrying the separate IVDD Type I mutation that significantly elevates rupture risk. This test is distinct from testing for the CDDY mutation itself.

• N/N (Clear): Normal risk for the breed
• N/IVDD: Elevated risk
• IVDD/IVDD: Highest risk

This test is offered by Embark and other panels for Dachshunds and other breeds.

Signs of IVDD — What to Watch For

• Sudden or progressive back or neck pain (hunching, reluctance to move, crying out)
• Weakness in the hind limbs (wobbly gait, dragging feet)
• Paralysis of the hind limbs
• Loss of bladder or bowel control
• Crying or reluctance to jump, climb stairs, or be picked up

Onset can be sudden. A Dachshund may go from normal to paralyzed within hours of a disc rupture.

Emergency treatment (surgical disc decompression) within 24-48 hours of paralysis onset significantly improves outcomes. Delay beyond 48 hours dramatically reduces the chance of functional recovery.

Summary

IVDD Type I in chondrodystrophic breeds is caused by disc calcification associated with the CDDY mutation. Dachshunds have a 25% lifetime IVDD risk. Radiographic disc screening at age 2 is the most practical breeding selection tool — dogs with fewer calcified discs should be preferred for breeding. Genetic testing for IVDD Type I modifier mutations is also available. IVDD disc rupture is a veterinary emergency; treatment within 24-48 hours of paralysis onset is critical for recovery.