Von Willebrand disease in dogs – symptoms, tests and treatment

Overview

The disease is abbreviated to vWD, and the missing or abnormal protein to vWF. It is the most common inherited bleeding disorder in dogs.

The disease has been described in more than 50 dog breeds, so it is not limited to Dobermanns. Severe disease can also occur in crossbreeds.

Von Willebrand disease is different from haemophilia, although both can cause excessive bleeding. Severity ranges from an asymptomatic trait to severe bleeding that starts spontaneously.

The disease generally affects a protein needed to support platelet function, rather than causing a shortage of platelets. The most common form is type 1, in which the clinical bleeding tendency may be mild or moderate.

Causes

The protein helps platelets stick

Platelets form the first plug at a damaged blood vessel, and vWF helps them attach to the injured vessel wall. The protein also contributes to platelets attaching to one another, although fibrinogen plays a more important role in their aggregation.

In addition, vWF carries clotting factor VIII and protects it from breakdown in the bloodstream. Cells lining blood vessels are among those that produce vWF and store it for later release.

The disease types differ

In type 1, there is too little protein, but its structure is normal. In type 2, a low protein level is accompanied by a structural abnormality that impairs its function.

In type 3, the protein level is extremely low or the protein is absent. Types 2 and 3 can cause more severe bleeding than the common type 1.

Inheritance is autosomal, so both males and females can be affected and pass the predisposition to their offspring.

Large chain-like protein structures are particularly important for function because they bind platelets more effectively. In type 2, these large structures are proportionally reduced, so the total protein level alone does not describe every functional defect.

A dog inherits one copy of the vWF gene from each parent, so family information is also useful when assessing inherited status.

Risk factors

Type 1 occurs in Dobermanns, Bernese Mountain Dogs, Golden Retrievers and Manchester Terriers, for example. Von Willebrand disease is a recognised inherited health condition in Manchester Terriers.

German Shorthaired Pointers and German Wirehaired Pointers are recognised risk groups for type 2. Predisposition to type 3 is known in breeds such as Scottish Terriers, Kooikerhondjes and Shetland Sheepdogs.

Reported prevalence in some predisposed breeds is 10–70%, but this is not a proportion applying to the whole dog population. Breed alone does not describe bleeding risk: an Airedale Terrier with type 1 may show signs less often than a Dobermann with the same type.

Infection or another concurrent clotting disorder can worsen an existing bleeding tendency.

Hormonal changes associated with a bitch's season or pregnancy can worsen the bleeding signs of an existing disorder.

Typical symptoms

Signs mainly involve mucous membranes, although the skin may also bruise more easily than usual.

• The gums bleed, for example during teething or while chewing a toy.

• Nosebleeds recur without an obvious external injury.

• Bleeding after nail clipping is heavier than expected.

• Urine becomes blood-stained even though no wound is visible.

• Gastrointestinal bleeding may appear as bloody vomit or black stools.

• A procedure wound oozes for a long time or starts bleeding more heavily than usual.

• Bruises appear on the skin after even a minor knock.

With mild disease, there may be no signs to notice at home before an injury or the first operation. Tiny pinpoint bleeds beneath the skin are not typical of this disease, so a low platelet count is investigated particularly when these occur.

Complications and consequences

Severe bleeding that does not stop can be life-threatening. Major blood loss can cause anaemia, in which a shortage of red blood cells reduces oxygen delivery to tissues.

Severe bruising around the surgical site has been described in a Shetland Sheepdog with type 3 despite a transfusion given beforehand. The outlook depends on the disease type and the bleeding risk it causes.

With careful planning, many dogs live a normal lifespan even though the inherited trait remains. Repeated transfusions can increase the risk of transfusion reactions, so choosing suitable blood products forms part of long-term treatment planning.

Diagnosis at the vet

Routine clotting tests may be normal

A blood count and platelet count are checked initially to look for other causes of bleeding. Platelet numbers are usually normal in von Willebrand disease.

Routine PT and APTT clotting times can also be normal, so these results do not rule out the disease. Mucosal bleeding time can be assessed at the veterinary practice using a small, controlled incision in the lining of the lip.

However, the bleeding-time test is not accurate enough to replace a specific vWF test.

Protein levels and genetic results answer different questions

The vWF:Ag test measures the amount of protein in a blood sample. In one laboratory's example classification, a normal level is 70–180%, a borderline result 50–69% and an abnormal result 0–49%.

A borderline result cannot definitively classify a dog as a carrier or clear of the trait. Most affected dogs that have bled have had levels below 35%, but this is not an absolute safety threshold.

Dogs with the most severe signs often have protein levels below 25%. In severe type 3 disease, the level may be no more than 1% of the reference level.

A collagen-binding assay assesses the protein's function rather than just its quantity. A DNA test identifies the inherited variant being tested, while a blood test alongside it assesses the current protein level.

The genetic test must suit the breed: for example, the Kooikerhondje type 3 test is not automatically the same as tests for other breeds. Not all disease-causing variants in every predisposed breed are known.

A carrier of a type 1 variant may also have a reduced vWF level, even though the test does not classify the dog as genetically affected. Levels vary from day to day and may change more during pregnancy, a season or systemic illness.

A sample taken when the dog is healthy and in a stable physiological state is most suitable for assessing inherited status. Puppies can be sampled as early as 6–8 weeks of age.

A clotted sample or one affected by red blood cell breakdown may give an unreliable result.

Protein levels can be measured by an immunological method in which antibodies bind the sample's vWF for measurement. A borderline measurement may be repeated if necessary and combined with an appropriate genetic test to clarify inherited status.

If vWF, screening clotting tests and platelet count are normal but the dog bleeds, other platelet function disorders can be investigated.

Sometimes clotting time is also prolonged when vWF deficiency is accompanied by reduced factor VIII activity.

Treatment

Stopping bleeding and preparing for procedures

Your vet prescribes treatment according to the severity of bleeding, disease type, test results and planned procedure. Bleeding from a smaller injury may be controlled with stitches, tissue adhesive or an appropriate dressing, for example.

Severe bleeding requires blood products suitable for the dog. Fresh frozen plasma or cryoprecipitate can temporarily replace missing vWF.

Blood products can also be used when essential surgery is needed. If blood loss causes oxygen deprivation and anaemia, a red blood cell transfusion may also be necessary.

Whole blood alone may not provide enough vWF to stop the bleeding. A plasma product given before surgery can reduce procedure-related bleeding risk.

Desmopressin helps only some dogs

Desmopressin releases stored vWF from cells in the blood vessel wall into the circulation. In Dobermanns with type 1, its effect on bleeding time may last up to around 4 hours.

Not all type 1 dogs respond, so surgical safety does not rely on this medicine alone. Desmopressin does not help in type 3 because there are no protein stores to release.

Repeated use can reduce the effect as stores become depleted. Thyroid hormone is not recommended as a treatment for von Willebrand disease itself.

Blood products have a temporary effect: they supply missing protein but do not change the dog's genes.

Prevention

An inherited disease cannot be prevented or removed once a dog has been born. Genetic testing for breeding and choosing an appropriate mate can reduce the number of affected puppies born.

One breed-club account dates the introduction of routine DNA screening for Kooikerhondje type 3 to 1998. Some breed-club rules accept Kooikerhondje matings in which both dogs are clear of the variant, or one is clear and the other a carrier.

Breeding from a dog that has bled abnormally or heavily is discouraged. Avoiding unnecessary cosmetic surgery reduces exposure to procedures that can cause bleeding.

Medicines that impair platelet function, such as acetylsalicylic acid, are avoided in affected dogs.

Mating a carrier to another carrier can produce more severely affected offspring, so this combination is avoided.

Important for dog owners

Keep the dates and laboratory reports from blood tests as well as the genetic result. Record nosebleeds, oozing wounds and bleeding after procedures. Note what triggered the bleeding and how it stopped. Photographs may help explain the event at the appointment.

Always mention the bleeding tendency before surgery, dental work or any other procedure that breaks the skin. Give your dog's carer a copy of the agreed emergency plan too. Check with the vet that new painkillers and other products are suitable before giving them.

Agree in advance where essential surgery can take place and how a possible transfusion will be prepared for. The word carrier on a genetic test does not provide all the information needed at the appointment: bring the previous bleeding history and protein-level result too.

Frequently asked questions

Is von Willebrand disease the same as haemophilia?

They are separate diseases, although both can cause prolonged bleeding. Von Willebrand disease affects the vWF protein that helps platelets attach. Haemophilia A results from factor VIII deficiency, so a precise diagnosis determines treatment planning.

Can a genetic-test carrier bleed more than usual?

A type 1 carrier may have a reduced protein level, so completely symptom-free carrier status cannot be assumed in every situation. If necessary, blood vWF is measured alongside the genetic result to assess bleeding risk. The assessment also considers the dog's previous bleeding history and the clinical variation typical of the breed.

Does a normal platelet count rule out the disease?

A normal platelet count does not rule out von Willebrand disease. Routine clotting tests can also remain normal despite a bleeding tendency. Specific testing of the protein level is therefore needed if suspicion remains, for example because of previous unexplained bleeding.

Can an affected dog have surgery?

Essential procedures can be planned in advance and supported with blood products where needed. Desmopressin may help some type 1 dogs, but does not replace all other preparations for bleeding. In a type 3 dog, desmopressin cannot replenish absent protein stores.

Can a dog live a normal lifespan?

Many dogs can live a normal lifespan when their bleeding risk is considered in veterinary care and everyday life. Disease type particularly affects the outlook, as a more severe protein deficiency increases bleeding risk. However, treatment does not permanently remove the disease. Unnecessary procedures and medicines that impair clotting are avoided to reduce risk.