Coagulation Factor VII Deficiency is an inherited blood clotting disorder. Factor VII (F7) is a protein essential for blood clotting. A deficiency causes frequent nosebleeds, excessive bruising and excessive or prolonged bleeding after an injury or surgery. Affected dogs may not show clinical signs until they undergo surgery and excessive bleeding occurs.
The single nucleotide substitution in the gene called F7 that causes Coagulation Factor VII deficiency in many breeds is recessive. This means that dogs that carry two copies of the mutation (homozygotes) will almost certainly develop Factor VII deficiency during their lives. Dogs that carry a single copy of the mutation (also known as carriers or heterozygotes) will not develop Factor VII deficiency as a result of the F7 mutation, but they will pass the mutation onto about half of any offspring they have. Breeding dogs that will not develop Factor VII deficiency should be the breeder’s priority, with a reduction in mutation frequency within the whole breed being the secondary, longer-term target.
Carriers can be bred from safely, provided they are mated to a dog that has also been tested and is clear of the F7 mutation (i.e. carry no copies of the mutation). If a carrier is mated to a clear dog approximately half of the resulting puppies will also be carriers, so should be tested themselves prior to breeding. Breeding carriers to tested, clear dogs is safe, in terms of avoiding dogs affected with Factor VII deficiency, and will help to maintain the genetic diversity of a breed. It is therefore encouraged, particularly in the first few generations following the availability of a new genetic test, so that other desirable characteristics and traits can be preserved before the frequency of the disease mutation within the breed is gradually reduced.