Von Willebrand Disease

TL;DR. Von Willebrand disease is an inherited bleeding disorder that impairs a pet's ability to form blood clots, making them highly vulnerable to excessive bleeding during surgery, injury, or teething.

Doberman Pinschers are genetically predisposed to von Willebrand disease.

What is it?

To understand von Willebrand disease (vWD), it helps to understand how a healthy body stops bleeding. When a blood vessel is damaged, the body initiates a complex process called hemostasis. The very first step, known as primary hemostasis, involves platelets, which are tiny, specialized cell fragments circulating in the blood. These platelets must quickly rush to the injury site, stick to the damaged vessel wall, and clump together to form a temporary plug.

However, platelets cannot stick to the blood vessel wall on their own. They require a specific molecular glue to bind them to the exposed tissue. This molecular glue is a large protein called von Willebrand factor (vWF). In pets with von Willebrand disease, this crucial protein is either deficient or structurally abnormal. As a leading veterinary internal medicine reference explains:

"The vWF molecule circulates coiled; it uncoils at the site of endothelial damage, binds to the subendothelium and then to the platelet receptors, and the platelets are reeled in to the site of injury. As a consequence, vWD is usually characterized by primary hemostatic defects (e. g. , petechiae, ecchymoses, mucosal bleeding). However, most dogs with vWD do not bleed spontaneously but bleed excess"
— Veterinary Internal Medicine, p. 1289

Without functional vWF, the platelets cannot be reeled in effectively. The temporary plug fails to form, leading to prolonged, uncontrolled bleeding. Veterinary medicine classifies vWD into three distinct types based on the nature of the protein deficiency:

• Type 1: This is the most common and generally the mildest form. The vWF protein is structurally normal, but there is a quantitative reduction in the total amount circulating in the blood. Many dogs with Type 1 vWD live normal lives and may only show signs of excessive bleeding during surgery or major trauma.
• Type 2: This is a more severe, qualitative defect. While some vWF is present, the large, complex structures of the protein (called multimers) are missing or malformed. Because these large multimers are critical for effective clotting, pets with Type 2 vWD have a significant risk of severe bleeding.
• Type 3: This is the most severe form, characterized by an absolute absence of vWF altogether. Pets with Type 3 vWD cannot form primary platelet plugs at all, leading to frequent, severe, and often spontaneous bleeding episodes.

While vWD is widely recognized as the most common inherited bleeding disorder in dogs, it can occasionally affect cats. Because feline cases are exceedingly rare, much of the diagnostic and treatment guidance for cats is extrapolated from established canine protocols.

Causes & risk factors

Von Willebrand disease is an inherited genetic condition. It is caused by mutations in the gene responsible for producing the von Willebrand factor protein. Because it is a congenital defect, pets are born with the condition, and it persists throughout their entire lives.

The mode of inheritance varies depending on the breed and the specific type of vWD. In many common breeds, the disease is inherited as an autosomal dominant trait with incomplete penetrance. Incomplete penetrance means that not every dog carrying the mutated gene will show the same severity of symptoms. Some may have very low vWF levels and bleed severely, while others with the same mutation may have near-normal clotting ability. In other breeds, the disease is inherited as an autosomal recessive trait, meaning a puppy must inherit two copies of the mutated gene (one from each parent) to be affected. Recessive forms typically result in the more severe Type 2 or Type 3 vWD.

According to a leading veterinary critical care textbook:

"Inheritance is autosomal dominant or recessive in type I but autosomal recessive in types II and III. No sex predilection has been found. Animals with vWD typically show mucosal bleeding..."
— Small Animal Critical Care Medicine, p. 636

Because there is no sex predilection, male and female pets are affected at equal rates.

Signs to watch for

Many pets with von Willebrand disease show no outward signs of illness. They can run, play, and live for years without their owners ever suspecting a clotting disorder. The first indication of a problem often occurs during a routine surgical procedure, such as a spay, neuter, or dental extraction, where the pet bleeds excessively and fails to form normal clots. When clinical signs do appear, they typically involve bleeding from the body's mucous membranes (mucosal bleeding) rather than deep tissue bleeding or joint swelling.

Common Signs

• Excessive bleeding during or after surgery
• Perinatal death, abortions, or stillbirths in breeding females
• Mucosal bleeding (such as bleeding from the nose or gums)

Occasional Signs

• Excessive bleeding during teething (when puppy teeth fall out) or during estrus (heat cycles in intact females)
• Diffuse oropharyngeal (mouth/throat) or vaginal bleeding
• Epistaxis (nosebleeds)
• Hematuria (blood in the urine)
• Melena (dark, tarry, or black stools, which indicate digested blood from the upper gastrointestinal tract)
• Gingival hemorrhage (bleeding gums)
• Excessive cavity bleeding after surgery (bleeding into the chest or abdominal cavity)

Rare Signs

• Petechiae (tiny, pinpoint red or purple spots on the skin or gums caused by minor capillary bleeding) and ecchymoses (larger, bruise-like patches)

Bleeding gums during teething can be an early sign of von Willebrand disease.

How vets diagnose it

Diagnosing von Willebrand disease requires a systematic, step-by-step approach. Because the symptoms of vWD mimic other bleeding disorders, your vet must rule out other potential causes before confirming a diagnosis. The diagnostic process typically begins with a physical examination and a review of your pet's breed and family history. If your vet suspects a bleeding disorder, they will recommend the following tests:

1. Platelet Count: This is always the first step. Your vet must rule out thrombocytopenia (a low number of platelets) before investigating functional platelet defects. As a leading critical care reference notes:

   "The typical physical examination finding in a known breed affected with vWD leads the clinician to measure a manual and automated platelet count. Thrombocytopenia must be ruled out before continuation through the ensuing coagulation work-up."
   — Small Animal Critical Care Medicine, p. 637

   If the platelet count is normal, but the pet is still bleeding excessively, the vet will proceed to functional testing.

2. Buccal Mucosal Bleeding Time (BMBT): This is a practical, in-clinic test that measures how well your pet's platelets and vWF work together to form a clot in real-time. Your vet will gently elevate your dog's upper lip and make a tiny, standardized incision on the inner surface of the lip using a spring-loaded device. They will then time how long it takes for the bleeding to stop completely. While a prolonged BMBT indicates a primary clotting defect, it is not specific to vWD alone, and a normal result does not completely rule out the disease.

3. PFA-100 Test: This is an advanced, automated screening tool used preoperatively in high-risk breeds. The PFA-100 system simulates high-shear blood flow through a microscopic aperture, measuring the time it takes for a platelet plug to block the opening. This test is highly sensitive for detecting platelet dysfunction and vWD prior to surgery.

4. vWF:Antigen Concentration Measurement (vWF:Ag): This is the gold standard test for confirming von Willebrand disease. A blood sample is collected and sent to a specialized veterinary coagulation laboratory. The lab measures the exact concentration of von Willebrand factor antigen in the plasma. Results are reported as a percentage compared to a pool of normal canine plasma. A level under 50% is diagnostic for von Willebrand disease, and pets with levels below 35% are at high risk for clinical bleeding.

5. Genetic Testing: DNA tests are available for several specific breeds. These tests can identify whether a dog is clear, a carrier, or affected by the specific genetic mutation responsible for vWD in their breed. Genetic testing is highly recommended for breeding dogs and can be performed at any age, even in young puppies.

Specialized laboratory tests are required to measure von Willebrand factor levels.

Treatment options

There is no permanent cure for von Willebrand disease, as the genetic defect cannot be corrected. However, the condition can be managed highly effectively, particularly when planning for surgical procedures or managing acute bleeding episodes.

First-Line Medical Therapy: Desmopressin (DDAVP)

Desmopressin is a synthetic hormonal agent and a vasopressin analogue. It is the primary medical treatment used to manage Type 1 vWD. When administered (typically via an injection under the skin or intranasally), desmopressin stimulates the cells lining the blood vessels (endothelial cells) to release their stored reserves of von Willebrand factor into the bloodstream. This temporary boost in circulating vWF levels improves clotting function for several hours. Your vet will often administer desmopressin approximately 30 minutes before a scheduled surgery to minimize the risk of excessive bleeding. It is important to note that desmopressin is only effective in pets that have stored reserves of vWF (primarily Type 1). It is generally ineffective for pets with Type 2 or Type 3 vWD, as they lack functional reserves of the protein.

Transfusion Therapy

For pets with severe forms of the disease (Type 2 or Type 3), or for any vWD-affected pet experiencing an active, life-threatening hemorrhage, transfusion therapy is the treatment of choice.

• Cryoprecipitate: This is a specialized blood product concentrated with large vWF multimers, fibrinogen, and factor VIII. It is the ideal transfusion product for vWD patients because it delivers a high concentration of the missing clotting factors in a small volume.
• Fresh Frozen Plasma (FFP): If cryoprecipitate is unavailable, fresh frozen plasma can be administered. FFP contains all clotting factors, including vWF, and helps restore normal hemostasis.

Supportive Care and Medication Safety

Managing a pet with vWD requires strict avoidance of medications that can impair platelet function. You must never give your pet aspirin, non-steroidal anti-inflammatory drugs (NSAIDs) like carprofen or meloxicam, or certain antibiotics (such as high-dose penicillins) unless specifically instructed by your vet. These medications can further compromise your pet's already weakened clotting system, triggering severe bleeding.

Prognosis

The long-term outlook for a pet with von Willebrand disease depends heavily on the specific genetic type they carry and how well the condition is managed.

• Type 1 vWD: The prognosis is generally excellent. Because Type 1 is a mild to moderate deficiency, most affected dogs live full, active, and normal lives. With proactive veterinary care—such as pre-surgical screening, the use of desmopressin, and avoiding platelet-inhibiting drugs—the risk of serious bleeding complications is very low.
• Types 2 and 3 vWD: The prognosis for these types is guarded to poor. Because these pets have a severe qualitative defect or an absolute lack of vWF, they are highly vulnerable to spontaneous, life-threatening bleeding episodes. Managing these pets requires intensive, lifelong vigilance, strict lifestyle modifications, and immediate access to emergency veterinary facilities capable of providing specialized blood products like cryoprecipitate.
• Feline Prognosis: Because von Willebrand disease is exceptionally rare in cats, long-term prognosis data in this species is highly limited. Feline cases must be managed on an individual basis with close veterinary supervision.

Prevention

Because von Willebrand disease is an inherited genetic disorder, it cannot be prevented through lifestyle changes, vaccines, or diet. The only way to prevent the disease is through responsible breeding practices.

• Genetic Screening: Breeders of predisposed dog breeds should perform DNA testing on all potential breeding stock before mating. Dogs identified as affected or carriers of recessive mutations should be removed from breeding programs to prevent passing the mutated genes to future generations.
• Pre-Surgical Screening: For owners of high-risk breeds, performing a pre-surgical screening (such as a PFA-100 test, BMBT, or vWF:Ag measurement) before routine procedures like spaying or neutering is highly recommended. This allows your vet to take appropriate precautions, such as having desmopressin or blood products on hand, before an incision is made.
• Home Management: If your pet has been diagnosed with vWD, you can prevent bleeding episodes by making simple lifestyle adjustments:
  • Avoid hard chew toys, bones, or antlers that can lacerate the gums.
  • Use a soft-bristled toothbrush for dental care.
  • Prevent rough play with other dogs that could lead to bruising or minor injuries.
  • Keep your pet on a leash during walks to prevent accidental trauma.

When to call your vet

If you own a breed predisposed to von Willebrand disease, or if your pet has been diagnosed with the condition, you must monitor them closely for any signs of bleeding. Contact your veterinarian if you notice:

• Prolonged bleeding from the gums, especially during teething or after eating hard food.
• Frequent or unexplained nosebleeds.
• Blood in your pet's urine or stool.
• Unusually heavy or prolonged bleeding during a female pet's heat cycle.
• Any minor cut or scratch that continues to ooze blood for more than a few minutes.

Emergency Red Flags
Seek immediate emergency veterinary care if your pet exhibits any of the following signs of severe internal bleeding or acute blood loss:

• Pale, white, or blue gums
• Sudden, extreme weakness or lethargy
• Collapse or inability to stand
• Rapid, shallow breathing or panting
• Cold ears, paws, or tail
• Uncontrolled, continuous bleeding from any wound or body orifice

For specific breeds

Von Willebrand disease has been documented in over 50 breeds of dogs, but certain breeds carry a significantly higher genetic risk. The mode of inheritance and severity of the disease vary by breed:

• Doberman Pinscher: This breed has the highest prevalence of vWD. The defect is inherited as an autosomal dominant trait with incomplete penetrance, typically resulting in Type 1 vWD. While many Dobermans are affected, the severity of bleeding can vary widely.
• German Shepherd Dog, Poodle, Golden Retriever, and Shetland Sheepdog: In these popular breeds, the disease is also inherited as an autosomal dominant trait with incomplete penetrance, usually presenting as Type 1 vWD.
• Scottish Terrier: This breed is predisposed to Type 3 vWD, which is inherited as an autosomal recessive trait. Affected Scottish Terriers have an absolute lack of vWF and face a high risk of severe, spontaneous bleeding.
• German Shorthaired Pointer and German Wirehaired Pointer: These breeds are predisposed to Type 2 vWD, inherited as an autosomal recessive trait. This qualitative defect leads to severe bleeding tendencies.
• Kooikerhondje: This breed is predisposed to Type 3 vWD, inherited as an autosomal recessive trait, resulting in severe clotting failure.

Sources

• Veterinary Internal Medicine, 5th Edition, pages 1288, 1289, 1290.
• Small Animal Critical Care Medicine, 2nd Edition, pages 636, 637.