Haemophilia can be produced by decreased or absent coagulation factors within the blood. These can be congenital or result from a failure to convert procoagulants to coagulants (factors II, VII, IX and X) due to vitamin K absence (cholestatic liver disease or malabsorption syndromes), or vitamin K antagonism (anticoagulant rodenticides) or consumption due to DIC.
A number of types of hemophilia have been recognized in dogs:
- Genetic clotting factor disorders
- - Factor I deficiency (Congenital afibrinogenemia) - Chihuahua, Bichon Frise, St. Bernard, Borzoi, Vizsla, American Collie
- - Factor II deficiency - Boxer, English Cocker Spaniel
- - Factor VII deficiency - Airedale Terrier, Alaskan Klee Kai, Beagle, Giant Schnauzer, Scottish Deerhound
- - Factor VIII deficiency (Hemophilia A) - Golden Retriever, Havanese, Weimaraner, German Shepherd, Chow Chow, Keeshonden, Irish Setter
- - Factor IX deficiency (Hemophilia B) - Rhodesian Ridgebacks, German Wirehaired Pointer, Bull Terrier, Lhasa Apso
- - Factor X deficiency - American Cocker Spaniel, English Springer Spaniel, Jack Russell Terrier - homozygous pups usually die, but heterozygous dogs unaffected
- - Factor XI deficiency (Hemophilia C) - Springer Spaniel, Great Pyrenees, Weimaraner, Kerry Blue Terrier
- - Factor XII deficiency (Hageman factor) - German Shorthaired Pointer, Standard Poodle, Miniature Poodle
- - Von Willebrand's disease - lack of functional von Willebrand factor (vWF) - Corgi, Doberman, German shepherd, German Short-Haired Pointer, Golden Retriever, Shetland Sheepdog, Standard Poodle
- Hereditary platelet disorders
- - Prekallikrein deficiency (Fletcher Trait) - Poodle, Shar Pei, German Short-haired Pointer, Shih Tzu
- - Glanzmann's Thrombasthenia Type I (Thrombasthenia) - Great Pyrenees, Otterhound
- - Thrombopathia - Basset Hound, Spitz, American Cocker Spaniel
- Hereditary complement deficiency
- Acquired platelet disorders
Clinically affected dogs are often young and present with buccal bleeding, epistaxis, rectal bleeding and anemia. There may also be prolonged bleeding from minor wounds and internal hemorrhage involving joints, muscles, and other tissues, with no antecedent trauma. Post-operative bleeding may be the first indication of this disease in some dogs.
Diagnosis is based on hematological signs of anemia, prolonged clotting time, coagulation screening tests (ELISA) and genetic testing. Affected males are accurately diagnosed based on coagulation Factor VIII assays. In contrast, carrier females appear clinically normal and may have Factor VIII values that overlap those of clear females. Hemophilia A is often propagated when these asymptomatic carrier females are used for breeding.
There is no cure for this disorder. Mildly affected dogs may never require treatment, or only after surgery or trauma.
In severely affected dogs, treatment options include periodic fresh or fresh frozen plasma fresh frozen cryoprecipitate (factor VIII) or cryosupernatant (factor IX) plasma. However, the development of neutralizing antibodies to replacement protein is a major complication of protein and enzyme replacement therapies.
Gene therapy has shown promise as well, utilizing the hyperactive (Sleeping beauty) transposase system to deliver adenoviral-factor VII and IX into the canine liver, resulting in correction of canine hemophilia B.
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