Hemophilia A (Discovered in the Labrador Retriever)

Hemophilia A, also known as Factor VIII Deficiency, is a blood clotting disorder that can cause bruising or abdominal bleeding without apparent reason. The associated genetic variant has been identified in the Labrador Retriever. However, please note that this variant does not explain all occurrences of Hemophilia A in the breed, indicating additional genetic causes remain to be discovered.

Key Signs

Spontaneous bleeding, Excessive bleeding, Internal bleeding, Hematomas, Joint swelling, Lameness

Age of Onset

At birth

Present at birth


X-linked Recessive

For X-linked recessive disorders, the genetic variant is found on the X chromosome. Female dogs must have two copies of the variant to be at risk of developing the condition, whereas male dogs only need one copy to be at risk. Males and females with any copies of the variant may pass the disorder-associated variant to their puppies if bred.

Likelihood of the Condition

High likelihood

At risk dogs are highly likely to show signs of this disease in their lifetime.

What to Do

Here’s how to care for a dog with Hemophilia A

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 Hemophilia A

Hemophilia A is an inherited bleeding disorder characterized by a deficiency in Factor VIII protein, which is necessary in the blood coagulation process. Clinical signs of Hemophilia A vary depending on the activity of Factor VIII in the blood. Signs may include excessive and prolonged bleeding following traumas or when shedding deciduous teeth, lameness and swelling of the joints, and subdermal hematoma formation. Bleeding into the chest or abdominal cavity may be observed in severely affected dogs and often carries a poor prognosis. The disorder follows an X-linked recessive mode of inheritance and, therefore, is more commonly observed in male dogs as males only have one X chromosome. Additionally, large or active dogs are usually associated with more severe signs.

To diagnose Hemophilia A, coagulation assays can be measured at a reference laboratory. In affected dogs, a prothrombin (PT) and partial thromboplastin time (PTT) should be measured prior to surgery or invasive procedures. Affected dogs should be monitored closely for excessive and prolonged bleeding during and after any required surgical procedures or following any trauma. Transfusions of cryoprecipitate or fresh-frozen plasma should be provided as necessary to ensure proper clotting if other means are unsuccessful.

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 X-linked recessive, meaning the genetic variant is found on the X chromosome. Given males only have one X chromosome, a single affected copy will increase the risk of being diagnosed with Hemophilia A (Discovered in the Labrador Retriever). Females typically require two copies to be at an elevated risk. Use of dogs with one or two copies of the Hemophilia A variant is not recommended for breeding as there is a risk that the resulting litter will contain affected puppies. Please note: It is possible that clinical signs similar to the ones caused by this variant could develop due to a different genetic or clinical cause.

Technical Details

Technical details are not available at this moment.