Chondrodystrophy and Intervertebral Disc Disease, CDDY/IVDD, Type I IVDD

FGF4 retrogene - CFA12

Skeletal

This condition is associated with differences in body proportions, such as a longer back and shorter legs, and may increase the risk of spinal disc problems. Disc disease can vary in severity, from mild discomfort to more serious movement changes.

Linkage testProvisional

Signs and symptoms

Research indicates that dogs with one or two copies of this variant have a similar risk of developing IVDD. However, there are some breeds (e.g. Beagles and Cocker Spaniels, among others) where this variant has been passed down to nearly all dogs of the breed and most do not show overt clinical signs of the disorder. This suggests that there are other genetic and environmental factors (such as weight, mobility, and family history) that contribute to an individual dog’s risk of developing clinical IVDD. Signs of IVDD include neck or back pain, a change in your dog's walking pattern (including dragging of the hind limbs), and paralysis. These signs can be mild to severe, and if your dog starts exhibiting these signs, you should schedule an appointment with your veterinarian for a diagnosis.

Signs of CDDY are recognized in puppies as it affects body shape. IVDD is usually first recognized in adult dogs, with breed specific differences in age of onset.

Diagnosis

For CDDY, dogs with one copy of this variant may have mild proportional differences in their leg length. Dogs with two copies of this variant will often have visually longer bodies and shorter legs. For IVDD, a neurological exam will be performed on any dog showing suspicious signs. Based on the result of this exam, radiographs to detect the presence of calcified discs or advanced imaging (MRI/CT) to detect a disc rupture may be recommended.

Treatment

What to do if your dog is at risk

Talk to your vet about your dog’s chondrodystrophy and intervertebral disc disease result so you can discuss how it may influence their daily activities and lifestyle.

This variant is very common in certain breeds, and many dogs with this result will not need any special accommodations because they are unlikely to develop symptoms. However, some breeds are at greater risk, and precautions may help reduce strain on the back and neck.

Keep your dog fit with regular, low-impact exercise and maintain a healthy weight to support spinal health.

Consider using ramps to access furniture, avoiding long flights of stairs, and choosing a harness instead of a collar to minimize stress on the spine.

Genetic information

Please note that this variant is extremely common in many small and chondrodystrophic dog breeds. In these breeds, this variant may not be the strongest predictor of IVDD risk compared to other genetic or environmental factors.

Penetrance: A dog with one copy of this variant may have slightly shorter legs in relation to body size. A dog with two copies of this mutation will have much shorter legs and a longer body. A dog with one or two copies of this variant has an increased risk of developing IVDD. Research has shown that one or two copies of this variant creates a 46 fold increase in risk for an IVDD event and a 5-15 fold increase in risk for disc surgery.

Gene: FGF4 - chr12
Inheritance type: dominant
Clinical category: Skeletal