Von Willebrand’s Disease

OVERVIEW: 

 

Von Willebrand’s disease, often referred to as Von Willebrand disease, von Willebrand's Disease, VWD, and vWD, is the most common blood clotting disorder found in domestic dogs.  The condition is caused by a deficiency in the production of Von Willebrand’s factor, a necessary component in the blood clotting process.  Von Willebrand’s Disease is named for the Finnish pediatrician Dr. Erik Von Willebrand, who first identified the disease in 1924 after working with a number of affected families in the Aland Islands.  Von Willebrand’s disease is one of the few conditions caused by genetic mutations which are nearly identical across multiple species, and is not only the most common blood clotting disorder in domestic dogs but also in human beings.  In fact, research into Von Willebrand’s disease in human beings has greatly influenced understanding of the disease in dogs and vice versa.

 

Blood is one of the most important parts of the canine body.  The fluid carries oxygen and nutrients throughout the entire body, and can be thought of as a highway providing the body with what it needs to function.  In order to constantly supply the body, blood must constantly flow through the circulatory system.  Were it not for blood clotting, this would mean that if a part of the circulatory system is punctured or severed blood would continue to flow out of that break until the dog died from blood loss.  Luckily, the blood clotting system exists to prevent exactly that.  Blood clotting is a very complex process that is designed to stop the blood from flowing out of an injury to the circulatory system.  In very simple terms, tiny cells known as platelets travel through the blood stream waiting for an injury to occur.  When an injury is located, the platelets become, “sticky,” or “activated.”  They then adhere to the walls of the circulatory system and to each other, forming a, “wall,” known as a, “white clot.”  At the same time, a number of free moving proteins and other molecules are also traveling through the blood stream, molecules which form the thrombin system.  When bleeding occurs, these molecules activate.  Once activated, these molecules begin to form long strands known as fibrin.  Fibrin strands stick to the circulatory system’s walls to form a web-like structure.  Fibrin webs begin to, “catch,” red blood cells and stick them together, forming a, “red clot.”  The fibrin webs also strengthen the, “white clots,” formed by platelets and join them to, “red clots.”  The combination of “white clots” and “red clots” forms what is known as a mature clot.  Mature clots form a, “wall,” which more blood cannot flow through, therefore protecting the body from additional blood loss.

 

Von Willebrand’s factor is one of the many proteins involved in the blood clotting process.  In normal dogs, enough of Von Willebrand’s factor is produced that there is no difficulty clotting.  In dogs with Von Willebrand’s disease, the body does not produce enough Von Willebrand’s factor, leading to a deficiency.  Because of this deficiency, the body has difficulty forming fibrin strands and the blood clots those strands create.  Without clotting to protect the body from blood loss, dogs with Von Willebrand’s disease bleed more than other dogs.  Von Willebrand’s disease is incredibly variable in its severity.  For example, some dogs with the condition may produce 99% as much Von Willebrand’s disease and would probably experience so little extra bleeding that the condition would never be noticed.  At the same time, other affected dogs produce almost no Von Willebrand’s factor at all and can bleed so excessively that even a minor injury is potentially life threatening.

 

There are three forms of Von Willebrand’s disease found in domestic dogs, each of which is caused by a different genetic mutation.  Type I is by far the most common form and has been identified in most dog breeds and mixes.  Although the exact genetic inheritance of Type I Von Willebrand’s disease is not yet fully understood, it is thought to be an autosomal trait with incomplete dominance.  This means that if the dog inherits the faulty gene from either parent, it will be impacted by the disease to some extent.  However, that extent varies tremendously from dog to dog and Type I Von Willebrand’s disease can cause a Von Willebrand factor deficiency of anywhere from 1% to 60%.  Interestingly, Type I Von Willebrand’s disease is also homozygous fatal, meaning that puppies which inherit two copies of the defective gene (one from each parent) will always die either in the womb or very shortly after birth.  Although the impact of Type I Von Willebrand’s disease varies greatly depending on the severity of the deficiency, this is generally the least serious and dangerous form.  Dogs suffering from Type I Von Willebrand’s disease often suffer nose bleeds, gum bleeds, extended periods of bleeding during heat, and greater blood loss during injuries, but most do not suffer from life threatening blood loss except in the case of major injury or surgery.

 

Type II Von Willebrand’s Disease is extremely rare in domestic dogs and has only been identified in a few breeds such as the German Shorthaired Pointer.  This condition is autosomal recessive, which means that only those dogs which have two copies of the defective gene (one from each parent) are affected.  Type II Von Willebrand’s disease is slightly different from the other two forms because it is not technically caused by a deficiency of the Von Willebrand factor.  Instead, this disease is caused by a slight malformation of the Von Willebrand’s factor that the body does produce, which makes it less useful for clotting.  Although dogs with Type II Von Willebrand’s disease technically produce just as much Von Willebrand’s factor as other dogs, their Von Willebrand factor is of such low quality that it functions just as if they did have a deficiency.  Type II Von Willebrand’s disease is often a very serious condition that can often result in fatalities if precautions are not taken. 

 

In domestic dogs, Type III Von Willebrand’s disease is both much less common than Type I and much more common than Type II.  Type II Von Willebrand’s disease is only commonly seen in a few breeds, although it has been identified in several others.  Type III Von Willebrand’s disease varies in severity depending on whether the affected dog has inherited one or two copies of the defective gene.  Dogs that have inherited two copies of the defected gene (one from each parent) do not produce any Von Willebrand factor at all.  Such dogs are at very risk of bleeding to death from even comparatively minor injuries.  Dogs that have inherited only a single copy of the defective gene (from either parent) will suffer from between a 15% and 60% Von Willebrand factor deficiency.  Such dogs will be impacted a variable amount depending on the extent of the deficiency.

 

Von Willebrand’s disease is a condition that generally does not cause problems on its own, but rather only when some complicating factor emerges.  The condition is usually unnoticeable unless the dog suffers a significant injury or requires surgery, although many affected dogs do suffer from nose and gum bleeds.  Some dogs may also experience internal bleeding problems.  Unfortunately, many cases are undiscovered until it is already too late and the dog is bleeding uncontrollably on the operating table.  All affected dogs have Von Willebrand’s disease from birth, but very few are diagnosed until between 3 and 5 years of age.  In general, Von Willebrand’s disease causes a dog to bleed more excessively whenever it would bleed otherwise, and may cause some bleeding on its own in areas of the body where the surface blood vessels are not protected by tough skin such as the gums, nose, reproductive organs, and the lower portions of the digestive tract.  Although there is not an exact correlation between the level of Von Willebrand factor deficiency and level of excessive breeding (for example a dog with a Von Willebrand factor deficiency of 20% will not necessarily bleed 20% more than a normal dog), there is a very strong general correlation (for example a dog with a deficiency of 60% is probably going to bleed significantly more than a dog with a 30% deficiency.

 

RISK FACTORS: 

 

Genetics – There is no greater risk factor associated with Von Willebrand’s disease than genetics.  Dogs whose close relatives have been diagnosed with Von Willebrand’s disease are much more likely to develop the condition than others.  This correlation is especially strong between parents and offspring and between littermates.

 

Breed – Certain breeds are much likelier to suffer from certain forms of Von Willebrand’s disease than others.  Type I Von Willebrand’s disease has been diagnosed in almost every breed (with a small number of exceptions) and is also quite common in mixed-breed dogs.  Among the breeds most likely to suffer from Type I Von Willebrand’s disease are the Scottish Terrier, Shetland Sheepdog, Golden Retriever, Standard Poodle, Miniature Poodle, Pembroke Welsh Corgi, Miniature Schnauzer, Basset Hound, German Shepherd Dog, Rottweiler, Manchester Terrier, Keeshond, Miniature Dachshund, and Standard Dachshund.  However, Type I Von Willebrand’s disease is both most closely associated with and most commonly seen in the Doberman Pinscher.  Some very reliable estimates believe that between 80% and 85% of all Doberman Pinschers are either have Von Willebrand’s disease or are carriers.  Type II Von Willebrand’s disease is very rare and is almost entirely limited to German Short-Haired Pointers.  Type III Von Willebrand’s disease is most commonly seen in the Scottish Terrier, Shetland Sheepdog, and the Chesapeake Bay Retriever.   

 

SIGNS & SYMPTOMS: 

 

Unless the dog is suffering from a severe case, many cases of Von Willebrand’s disease are essentially unnoticeable until a major injury or surgery.  However, there may be many warning signs.  Because Type I is fatal to all affected puppies either in the womb or shortly after birth, the presence of stillborn pups or pups that die shortly after birth in a litter is evidence that the parents and littermates may have Von Willebrand’s disease.  Certain areas of the body are not protected by as much or the same type of skin, meaning that the circulatory system is also less protected.  Dogs with Von Willebrand’s disease often bleed from such areas, often for seemingly no reason.  Among the most common locations are gums, oral mucosa, nose, and anus.  These episodes may either be regular or very sporadic depending on the dog.  Von Willebrand’s disease also makes a dog more susceptible to internal bleeding, especially in those body systems which have some form of contact with materials from outside the body.  Dogs suffering from Von Willebrand’s disease often may experience rectal or urinal bleeding which can be detected by bloody or black tarry stool and bloody or red urine respectively.  In many cases, Von Willebrand’s disease is first noticed when the dog seems to bleed an excessive amount and/or an excessively long time from routine procedures including tail docking, ear cropping, dew claw removal, and toe nail clipping.  Similarly dogs may seem to bleed excessively or for an excessively long time after minor injuries such as scrapes and cuts, during heat cycles in the case of female dogs, and/or during whelping (giving birth).  Dogs with Von Willebrand’s disease may also exhibit regenerative anemia and/or abnormal thyroid hormone levels.  If early warning signs are either not present or unnoticed, serious bleeding problems may appear after major injuries or during major surgeries.

 

DIAGNOSIS & TESTS: 

 

Unfortunately, it is very difficult, if not nearly impossible, to get a definitive diagnosis for Von Willebrand’s disease in most dog breeds because the proper tests are unavailable.  However, conclusive diagnoses are possible in those breeds where such tests are available and very strong diagnoses can be made in other breeds from other tests.  To begin diagnosis, veterinarians will consider the full extent of a dog’s symptoms, such as frequency and amount of bleeding.  They will also strongly take into account the dog’s breed and family history.  Two diagnostic tests are considered the most useful and are performed in virtually all cases where Von Willebrand’s disease is suspected regardless of breed.  The first is known as a bleeding time assessment.  A small incision is made on the dog’s gum and allowed to bleed.  The veterinarian will then see how long it takes before the cut stops bleeding on its own.  Normal dogs take 2 to 4 minutes before bleeding stops.  Anything longer is indicative of a bleeding disorder.

 

Although very useful as a first step, bleeding time assessments are not conclusive because a number of disorders including platelet deficiencies and thyroid problems may also cause excessive bleeding times.  The second test is a blood test.  A small sample of blood is taken and then checked for Von Willebrand’s factor.  This test is much more specific than bleeding time assessments because it shows that a Von Willebrand’s factor deficiency is the cause of the dog’s excessive bleeding, but it is still not definitively conclusive because other conditions, such as hypothyroidism, may cause decreased levels of Von Willebrand’s factor.  In most cases, other tests will be performed at the same time, such as analysis of thyroid hormone levels, to help rule out other potential causes.  Eliminating as many other potential causes as possible can allow a veterinarian to make a much sounder diagnosis of Von Willebrand’s disease, but it cannot make one definitive.  Despite these limitations presented by bleeding time assessments and blood tests, they are the only available method available to diagnose Von Willebrand’s disease in most breeds and mixes.  Another major limitation of these methods is that they will not work for dogs with very minor cases of Von Willebrand’s disease.  For example, a dog with the gene responsible for Von Willebrand’s disease may only have a 5% Von Willebrand factor deficiency, a deficiency which is so small most tests will either not pick it up or it will be assumed to be within the normal range.

 

Recently, genetic tests have been developed for a small number of breeds that make it possible for laboratory workers to examine a dog’s DNA for the presence of the mutations responsible for Von Willebrand’s disease.  This testing method only works for certain breeds and is generally significantly more expensive than other available tests.  However, DNA testing is both the only way to conclusively confirm a diagnosis of Von Willebrand’s disease and the only way to identify the condition in some very minor cases.  Such tests are especially useful to breeders who can eliminate dogs from their breeding programs which otherwise may have passed the defective gene to their offspring.  Currently, genetic tests for Von Willebrand’s disease have been developed for the Doberman Pinscher, Scottish Terrier, Shetland Sheepdog, Manchester Terrier, Pembroke Welsh Corgi, and all three sizes of Poodle, although tests are in the development and/or testing process for several other breeds and may become available in the near future.
 

 

CONVENTIONAL TREATMENT & MANAGEMENT: 

 

Von Willebrand’s disease is a genetic condition that is a fundamental part of an individual dog’s genetic makeup.  This means that it is incurable, and will be present for a dog’s entire life.  Von Willebrand’s disease can, however, by managed very successfully in most cases, allowing the dog to live a relatively normal life.  The goal of Von Willebrand’s disease treatment is to reduce spontaneous bleeding episodes as much as possible, to reduce the severity of induced bleeding episodes (those resulting from injury or surgery), and to correct any other conditions which may exacerbate the bleeding problem.

 

One of the most important steps in Von Willebrand’s disease management is to take precautions to ensure that the dog is not injured in the first place.  Rough play with both humans and other dogs should be avoided at all costs.  Any activities which are likely to cause injury, even minor ones, should be avoided as well.  When injuries do occur, they must be treated swiftly and thoroughly.  In cases of minor injuries, owners should apply pressure and bandages until the bleeding stops.  More severe injuries, or minor ones which do not stop bleeding, should be treated by a veterinarian as rapidly as possible.  Because many dogs with Von Willebrand’s disease suffer from gum bleeds, owners should protect their mouths to the greatest extent possible.  Depending on the severity of the condition, dry or hard foods should be eliminated from the diet in favor of wet or soft ones.  Many types of treats, bones, and chew toys should also be kept away from dogs in favor of ones that are less harsh on the mouth.  Although all dogs with Von Willebrand’s disease should probably be fixed to prevent them from breeding, this is especially true of females because the condition causes excessive bleeding during estrous and whelping that could become serious or even fatal.

 

Dogs with minor cases of Von Willebrand’s disease will usually be fine with proper preventative measures.  However, dogs with severe cases may require blood transfusions both to make up for blood loss which has already occurred and to prevent future blood loss.  These transfusions range in frequency from very sporadic to very regular depending on the severity of the condition.

 

Veterinarians also must exercise special care when treating dogs with Von Willebrand’s disease.  Any medication with antiplatelet or anticoagulant effects should be avoided at all costs.  Some examples include non-steroidal anti-inflammatory drugs (NSAIDs),  estrogens, cytotoxic medications, heparin, coumadin, plasma expanders, and sulfonamide.  Veterinarians will also have to carefully consider all surgical options.  For dogs undergoing major surgery or with severe cases, it is often advisable to perform a blood transfusion prior to the operation as a preventative measure.  Veterinarians should also attempt to perform the least risky surgical option, oftentimes if it is not necessarily the best option.  In some cases, veterinarians may decide that the risk of surgery is too great and will select other treatment options.

 

The body is a very complex system and many different medical problems may work together to worsen the effects of Von Willebrand’s disease.  For example, a number of thyroid and platelet problems also result in blood clotting difficulties and can further increase the excessive bleeding caused by Von Willebrand’s disease.  Any such problems should be treated in an appropriate manner to reduce the potential effects of Von Willebrand’s disease.  Dog’s with Von Willebrand’s disease should be tested for other bleeding problems, especially thyroid problems, on an annual basis and treated for them if they develop.

 

POTENTIAL COMPLICATIONS: 

 

Von Willebrand’s disease can cause essentially any potential complication from excessive bleeding.  Perhaps the most common is anemia, or a deficiency of red blood cells.  Anemic dogs have problems supplying their body with enough oxygen and other nutrients to function properly.  Luckily, Von Willebrand’s disease causes only temporary anemia which lasts only as long as it takes for the body to replenish red blood cells, but the cumulative effects of long term anemia caused by Von Willebrand’s disease can be severe and impact any part of the body.  Internal bleeding caused by Von Willebrand’s disease can also cause complications ranging from skin bruising to internal organ damage.  The internal bleeding caused by Von Willebrand’s disease is often the most severe in a dog’s joints, which are constantly rubbing up against each other.  If this bleeding around the joints is severe and long-term enough, it can cause major joint problems such as arthritis and restriction of movement.

 

Most of the severe complications from Von Willebrand’s disease are the result of dogs with Von Willebrand’s disease experiencing a major injury or undergoing major surgery.  At a very basic level, Von Willebrand’s disease may make it so that the dog does not stop bleeding and dies of blood loss.  However, other complications may arise as well.  For example, blood might fill the lungs and cause the dog to drown, or fill the throat and cause the dog to choke to death.  These effects may also be magnified if the dog is taking certain medications.

 

Although most treatment methods for Von Willebrand’s disease may seem innocuous they may have some complications.  For example, changing a dog’s diet may result in digestive problems such as vomiting, diarrhea, and upset stomachs, problems which may cause additional bleeding due to the Von Willebrand’s disease.  Preventing a dog from performing potentially dangerous activities may cause the dog emotional distress if it greatly enjoyed them or weight gain if they are not replaced by equally vigorous activities.

 

Although the relationship between the two conditions is unclear, there is a very strong correlation between Von Willebrand’s disease and thyroid problems.  At this time, it is not understood whether this correlation is causal (meaning that one problem causes the other) or relational (meaning that the same genetic defects which are responsible for one condition influence the development of the other).  Regardless, dog’s which have been diagnosed with Von Willebrand’s disease should be checked for thyroid problems on an annual basis.  This is especially the case because thyroid problems can exacerbate the blood clotting problems cause by Von Willebrand’s disease, in addition to their many other deleterious impacts.

 

HOLISTIC REMEDIES: 

 

Because Von Willebrand’s disease is a genetic condition which is an inherent part of a dog’s DNA, it cannot be cured through holistic remedies.  Holistic remedies may, however, be helpful in mitigating the symptoms of Von Willebrand’s disease, mainly the excessive bleeding it causes.  To begin with, many holistic healers recommend feeding dogs natural diets, especially ones with raw meat.  It is believed that these natural diets are easier on a dog’s mouth and digestive system, therefore preventing gum bleeds and internal bleeding.  Many holistic veterinary healers also recommend various dietary supplements which are thought to strengthen and improve the health of a dog’s blood.  It is thought that stronger and healthier blood will not only bleed less but recovery faster from any loss that does occur.  Among the most commonly suggested supplements include iron, calcium, vitamin K, alfalfaAlfalfa when used as an additive in pet feeds is typically advertised as being one of the most nutritionally complete food additives. Click here for a full definition of this products use in pet food. (Medicago sativa), and shepherd’s purse (Capsella bursa-pastoris).  Always inform holistic veterinary healers if your dog has been diagnosed with Von Willebrand’s disease because many herbal remedies (such as acupuncture and fish oil) may either cause bleeding or have a deleterious impact on blood clotting and actually worsen the condition.  Additionally, always consult with a veterinarian before using any holistic remedies to ensure that they will not cause problems when working when combined with other medications.

 

PREVENTION & HELPFUL TIPS: 

 

Because Von Willebrand’s disease is a genetic defect that is present in a dog since conception, it is not possible to prevent the condition from developing.  It is, however, possible to prevent a dog from bleeding in many cases.  The methods are described in much greater detail in the Conventional Treatment and Management section, but they include providing a wet, soft diet, carefully selecting treats and chew toys, eliminating rough play, preventing a dog from engaging in potentially injurious activities, and spaying female dogs.

 

Although the exact inheritance mechanisms have not been discovered for all forms of Von Willebrand’s disease in all breeds (in fact only a very small minority have been), all agree that Von Willebrand’s disease is a genetically inherited condition.  It is very strongly recommended that all dogs which have been diagnosed with Von Willebrand’s disease be spayed or neutered to prevent them from breeding, and in most cases similar precautions should be taken with the parents, siblings, and offspring of all impacted dogs.  In cases where genetic tests are available for Von Willebrand’s disease do exist, an affected dog’s relatives which have been conclusively shown to not have or be carriers for Von Willebrand’s disease can usually be bred safely.  Such restrictive measures may not be possible or desirable at this stage for the Doberman Pinscher.  Recent testing indicates that between 80% and 85% of all Doberman’s carry the gene responsible for Von Willebrand’s disease.  This means that breeding only clear to clear dogs may severely reduce the breed’s genetic diversity.  Doberman breeders will probably have to develop a comprehensive long term breeding strategy, which may take decades, to gradually reduce the prevalence of Von Willebrand’s disease in their breed.

 

Owners of dogs which have exhibited the bleeding symptoms characteristic of Von Willebrand’s disease as well as any owners of breeds known to be impacted by the condition, especially Doberman Pinschers, should always notify their veterinarians from as early an age as possible.  Diagnosis of Von Willebrand’s disease is most helpful if it is made before any medications which may worsen the condition are prescribed and especially before any surgeries are conducted.  If a veterinarian knows that a dog has Von Willebrand’s disease before it is operated on, special precautions can be taken to help ensure its safety.  Unfortunately, many dogs have died on the operating table as a result of uncontrollable bleeding caused by undiagnosed Von Willebrand’s disease.

 

 

Von Willebrand Disease (VWD) is an inherited, common disease found in both dogs and humans. It is characterized by a deficiency of a protein called von Willebrand factor, which is involved in blood clotting. The disease varies from mild to severe, depending on the amount of von Willebrand factor present in the dog. Signs include spontaneous bleeding and excessive bleeding following surgery, injury, or during an estrous cycle.