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Hemophilia A (Discovered in the Havanese)

Hemophilia A, also known as Factor VIII Deficiency, is a blood clotting disorder, which can cause bruising or abdominal bleeding without apparent reason. The disease is more commonly seen in male dogs.

Key Signs

Potentially life threatening bleeding events, Hematomas, Abdominal bleeding

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

Blood coagulation is a complex process. Factor VIII is one of the proteins necessary for the blood coagulation process and a deficiency of this protein causes hemophilia A in an affected dog. Clinical signs of hemophilia A vary depending on the activity of factor VIII in the blood. Specific factor assay may be measured by a reference laboratory. Hematomas or abdominal bleeding without apparent reason may be observed in a severely affected dog. If untreated, the disorder can lead to death caused by bleeding. The condition is usually more severe in large, active dogs. Prior to surgery or invasive procedures, a prothrombin (PT) and partial thromboplastin time (PTT) should be measured. Additional supportive measures, including transfusions, may be necessary.

Exceptionally excessive and prolonged bleeding may be observed during shedding of deciduous teeth, routine surgeries, and even minor traumas. Prior to surgery or invasive procedures, a prothrombin (PT) and partial thromboplastin time (PTT) should be measured. Affected dogs should be monitored closely for excessive and prolonged bleeding during and after any required surgical procedures or after 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 the disorder. Females typically require two copies to be at an elevated risk. Use of dogs with one or two copies of the 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

Variant Insertion
Chromosome X
Coordinate Start 122,957,473
Coordinate End 122,957,472

All coordinates reference CanFam3.1

References & Credit

Credit to our scientific colleagues:

Wilhelm C, Czwalinna A, Hoffmann M, Mischke R, Ganser A, Von Depka M. A mutation leading to a stop codon in the FVIII gene is the cause of severe canine Hemophilia A. J Thromb Haemost 1 Sup P0672, 2013. View the article