My dog Lola was recently diagnosed with this disease. While not as common as it is in humans, it does occur frequently in canines. To help all those that have so generously donated to keep my baby alive understand more of what she is going through and to help educate others on this devastating illness I have created this page.
What is hemophilia?
Hemophilia is a bleeding disorder of varying severity that is due to a deficiency in specific clotting factors. Normally the body responds to an injury that causes bleeding through a complex defence system. This consists of local changes in the damaged blood vessels, activation of blood cells called platelets, and the coagulation (clotting) process. Most inherited bleeding disorders are the result of abnormal platelet function or a deficiency in one or more of the factors involved in the blood clotting system. Hemophilia is the most common inherited coagulation factor deficiency. Hemophilia A is a result of a deficiency of factor VIII, and hemophilia B of factor IX. Hemophilia A is more common than hemophilia B, and varies in severity depending on the level of factor VIII activity. Hemophilia B is often a severe bleeding disorder.
How is hemophilia inherited?
Hemophilia is an X-linked,recessive disorder. It is one of the few sex-linked traits in dogs. Because males have only 1 X chromosome, a male dog is either affected or clear of the defect. Females, with 2 X chromosomes, may be affected (abnormal gene on both chromosomes), clear, or a carrier with no clinical signs (one gene affected). In effect, the disease is carried by female.
What does it mean for your dog?
Dogs with mild forms of hemophilia may experience few or no signs, and may never require treatment until/unless surgery or trauma is followed by excessive bleeding.Where hemophilia is more severe, you may see signs of a problem at a fairly early age. Your pup may have prolonged bleeding associated with the loss of baby teeth, or unexplained areas of bleeding under the skin. Bleeding into muscles or joints will often cause lameness.Once the condition is diagnosed, your veterinarian will discuss ways to manage this lifelong problem. These include being alert for signs of bleeding episodes in your dog, and tips on housing and maintenance so as to minimize risks of bleeding. Periodic blood transfusions will generally be required.Unfortunately, dogs with severe hemophilia often die or are euthanized because of recurrent or uncontrollable bleeding problems and the high cost of treatment.
How is hemophilia diagnosed?
The clinical signs associated with hemophilia vary widely, based on the severity of the bleeding disorder and where in the body the bleeding occurs. Because this is a sex-linked disorder, dogs with hemophilia are almost always male, but can also occure in females. Affected dogs are commonly brought to the veterinarian for problems such as bloody diarrhea that is difficult to control, areas of bleeding under the skin, or lameness (due
to bleeding into muscles or joints). Bleeding under the skin or into the muscle may occur after routine vaccination, or there may be prolonged or severe bleeding at surgery (such as when your dog is neutered or spayed.) Other less common problems include respiratory difficulties due to bleeding into the chest or around airways, or weakness, paralysis, or even sudden death due to bleeding into the brain or spinal cord.Once a bleeding disorder is suspected, specialized laboratory tests are carried out to diagnose the specific disorder. If your pup is diagnosed with hemophilia, it is important that you inform the breeder so that he or she can have your dog's parents tested. (The mother is likely a carrier and the father free of the defect.)
Clinical signs: Signs are highly variable and often non-specific: unthriftiness, acute blood loss anemia, unexplained sub-cutaneous masses, hematomas (often at injection sites), refractory bloody diarrhea. Other signs depend on the local physiologic impact of hemorrhage: for example bleeding into the brain or around nerve trunks will cause neurologic signs, and bleeding around airways or into the pleural cavity will cause respiratory signs. Lameness is commonly associated with hemorrhage into muscles or joints, especially in larger breeds.
Laboratory: normal PT (prothrombin time) and prolonged aPTT (activated partial thromboplastin time); definitive diagnosis requires a specific assay for factors VIII and IX. Factor activity will be markedly decreased. Specific factor assays are also required to screen for female carriers (heterozygotes), who usually have about 40 to 60% of normal factor activity. Consult your diagnostic laboratory for specific information about sample collection and submission.
How is hemophilia treated:
There is no cure for this disorder. Mildly affected dogs may never require treatment, or only after surgery or trauma. Although recent studies have had evidence of a total cure in dogs and mice with repeated treatment. There is an entire colony of dogs with hemophilia in Chapel Hill, North Carolina. There have also been many experiments with mice. There have also been several experiments with humans.
Hemophilia gene therapy works. The genetically altered cells produce factor. The cells survive and reproduce. Some of the 1990’s experiments maintained factor levels for several months. Now the results are even more promising.
Some of the trials have maintained blood clotting factor levels for over 3 years and these trials are ongoing. These animals are still being studied. It is only a matter of time before these processes are perfected. A day will come when a person or canine with hemophilia will go to a treatment center and leave without hemophilia.
With more severe hemophilia, your dog will require periodic transfusions when bleeding occurs, to replace the deficient coagulation factor activity. Strict cage rest is important along with transfusion, to decrease further hemorrhage.
The very near future:
Progress in gene therapy to treat haemophilia has been impressive in the past few years. Gene therapy has been used to successfully treat haemophilia in dogs. A leading researcher from Philadelphia USA, Professor Katherine High, is examining the obstacles to successful gene therapy in human patients with hemophilia. She hopes that the problems may be overcome in the next five years to develop a successful gene transfer approach for sufferers of hemophilia.
Gene therapy
"It has taken approximately 5 to 8 years to move from a cure for hemophilia in mice to a cure in dogs. This has been achieved by multiple gene transfer strategies. Clinical studies have identified which aspects of gene transfer therapy in dogs are directly applicable in humans and have identified potential problems, such as mode of delivery, which must be overcome before applying this approach in humans," This cure is what we are hoping for in Lola and why we are fighting so hard to see that she receives the treatments needed.
