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Bernard-Soulier Syndrome (Discovered in the Cocker Spaniel)

Bernard-Soulier Syndrome (BSS) is a bleeding disorder in which platelets cannot bind together normally, leading to delayed blood clotting. The condition is characterized by larger than normal platelets and variably low platelet numbers, known as macrothrombocytopenia. The associated genetic variant has been identified in the Cocker Spaniel.

Found in

1 in 11,000 dogs

in our testing

Key Signs

Bruising, Nosebleeds, Gingival bleeding, Prolonged bleeding after injury or blood draws, Excessive bleeding after mating or birthing puppies

Age of Onset

0 to 2 yrs

Juvenile onset


Autosomal Recessive

For autosomal recessive disorders, dogs with two copies of the variant are at risk of developing the condition. Dogs with one copy of the variant are considered carriers and are usually not at risk of developing the disorder. However, carriers of some complex variants grouped in this category may be associated with a low risk of developing the disorder. Individuals with one or two copies may pass the disorder-associated variant to their puppies if bred.

Likelihood of the Condition

Moderate likelihood

At risk dogs may show signs of this disease in their lifetime, although some will not develop the condition due to absence of additional risk factors.

What to Do

Here’s how to care for a dog with BSS

Partner with your veterinarian to make a plan regarding your dog’s well-being, including any insights provided through genetic testing. If your pet is at risk or is showing signs of this disorder, then the first step is to speak with your veterinarian.

For Veterinarians

Here’s what a vet needs to know about BSS

Bernard-Soulier Syndrome is associated with a defect in platelet adhesion and is characterized by macrothrombocytopenia (abnormally large platelets that are variably low in count), although granulation is typically normal. Clinical signs are likely present at birth but are usually first observed between 2 and 4 years of age in affected dogs, and may be overlooked until a traumatic episode occurs. Often one of the first findings is prolonged bleeding and hematoma formation after venipuncture. Ecchymosis (bruising), gingival bleeding or epistaxis (nosebleeds) may also be noted. Other signs can include hematuria (blood in the urine), gastrointestinal bleeding, or bleeding after mating or whelping. Affected dogs are likely to show prolonged bleeding after trauma or surgery. BSS may be mistaken in some cases for immune-mediated thrombocytopenia due to similarity in presentation. Although worsening of signs with age has been reported in humans, signs appear to remain stable in affected dogs.

Care should be taken to avoid injuries in affected dogs. It is not uncommon for affected dogs to need blood transfusions during their lifetimes. Therefore, preemptive blood typing is recommended and crossmatching is recommended prior to any surgical procedures. Treatment may include transfusion of whole blood or platelet rich plasma during episodes of hemorrhage. Caution must be used when administering medications which can inhibit platelet aggregation (such as NSAIDs), and immunosuppressive treatment may be contraindicated in affected individuals.

For Breeders

Planning to breed a dog with this genetic variant?

There are many responsibilities to consider when breeding dogs. Regardless of test results it is important that your dog is in good general health and that you are in a position to care for the puppies if new responsible owners are not found. For first time or novice breeders, advice can be found at most kennel club websites.

This disorder is autosomal recessive, meaning that two copies of the variant are needed for a dog to be at an elevated risk for being diagnosed with the condition. A carrier dog with one copy of the Bernard-Soulier Syndrome (Discovered in the Cocker Spaniel) variant can be safely bred with a clear dog with no copies of the Bernard-Soulier Syndrome (Discovered in the Cocker Spaniel) variant. About half of the puppies will have one copy (carriers) and half will have no copies of the variant. Puppies in a litter which is expected to contain carriers should be tested prior to breeding. Carrier to carrier matings are not advised as the resulting litter may contain affected puppies. Breeding of affected females may result in excessive bleeding after mating and during whelping. Please note: It is possible that disorder signs similar to the ones caused by this Bernard-Soulier Syndrome variant could develop due to a different genetic or clinical cause.

Technical Details

Gene GP9
Variant Deletion
Chromosome 20
Coordinate Start 3,025,814
Coordinate End 3,028,273

All coordinates reference CanFam3.1

References & Credit

Credit to our scientific colleagues:

Gentilini, F., Turba, M.E., Giancola, F., Chiocchetti, R., Bernardini, C., Dajbychova, M., … Drögemüller, C. (2019). A large deletion in the GP9 gene in Cocker Spaniel dogs with Bernard-Soulier syndrome. PLoS One, 14(9), e0220625. View the article