Could my dog have a clotting disorder? 

Clotting disorders are not always as dramatic as we have been led to believe. Excessive bleeding or widespread bruising can definitely be a sign, but some symptoms can be much more subtle than that. When a dog cannot control the way their blood clots properly it can lead to some very vague signs including lethargy, lameness and collapse. In some cases, excessive bleeding may not occur until your dog has a major trauma or surgery.  

There are many different reasons why your dog’s blood might not be clotting properly and understanding this will be crucial to their recovery.  

We’re going to explore the many different clotting disorders in dogs, as well as the steps your vet will take to get to the bottom of things.  

What happens during normal blood clotting? 

Clotting is the body’s ability to stop bleeding, also known as haemostasis. This is not only important in cases of accident and injuries, but also for day-to-day life. 

Successful clotting relies on several things. These include – 

• Enough blood clotting proteins (also known as ‘clotting factors’) 

• The right number of platelets in the blood (small cell fragments that form a “plug” in a damaged blood vessel) 

• Blood vessels that properly constrict in response to injury. This slows the amount of blood passing through allowing clotting to begin. 

When an injury occurs the blood vessel will constrict (narrow), and platelets will then attach themselves to the wall of the broken blood vessel. Proteins (factors) act to change the shape of the platelet cells, making them more sticky so that they can clump to each other, the vessel wall and red blood cells. Other proteins make long strands known as fibrin. Fibrin strands will form a mesh-like net to further hold platelets and blood cells together, creating a plug or clot. This will seal the hole in the blood vessel wall, stopping any further bleeding.  

What causes a clotting disorder? 

A clotting disorder can occur due to many different reasons, so things are about to get complicated! We have listed many of the different causes of clotting issues here so that you can understand why your vet may need to perform a few tests to get a diagnosis. This list also indicates which of the clotting disorders are likely to be life-limiting.  

The Merck Veterinary Manual divides clotting disorders into categories as follows –  

Congenital clotting disorders 

Deficiencies in the proteins (factors) needed for blood to clot can cause issues. Congenital disorders are present from birth and can cause some puppies to die shortly after being born. Due to its hereditary nature, certain breeds are more likely to be affected than others by some of these conditions. Examples of congenital clotting disorders include – 

Factor II (prothrombin) disorders  

Rare, but issues with this factor have been found in Cocker Spaniels and Boxer Dogs. Signs in affected puppies improve with age, but adult dogs may bruise easily or have inflamed skin. 

Factor II deficiency  

Reported in breeds like Alaskan Malamutes, Beagles, English bulldogs, Boxers and Miniature Schnauzers. Affected dogs may have bruising or excessive bleeding after surgery or giving birth.  

Factor VIII deficiency (Haemophilia A)  

One of the most common inherited bleeding disorders. Females can carry the gene for this disorder without showing signs, but males will show signs. Affected animals can be affected to varying degrees, they may have prolonged bleeding from the umbilical cord after birth, from the gums during teething, or after surgery. Others may show lameness from a sudden bleed into a joint or blood loss can occur into a body cavity. 

Factor IX deficiency (Haemophilia B)  

Less common than Haemophilia A, but signs are very similar.  

Acquired Clotting Disorders 

Animals that are born normally can develop or acquire a clotting disorder later on. This most commonly occurs in animals with severe liver disease. The liver is responsible for manufacturing clotting factors. Injury or diseased will stop it from doing its job properly.  

Poisoning

Dogs that eat rodenticide (rat poison) may develop clotting issues. The poison can reduce the liver’s ability to produce clotting proteins, leading to widespread issues. There is usually a delay of 24 hours or more between eating the poison and showing symptoms. If you suspect your dog has eaten rat bait then call a vet immediately, don’t wait to see if they become unwell.  

Disseminated intravascular coagulation (DIC)

This very serious condition can develop as a result of issues like sepsis, heat stroke, cancer or other severe injury. It causes small blood clots to form in vessels throughout the body, potentially blocking them. This process consumes many of the dog’s clotting factors, so they are unable to control their bleeding. Bloody vomiting and diarrhoea can occur, as well as bruising. It can be fatal, especially if not treated early. 

Infection with lungworm (Angiostrongylus vasorum)

These parasites can also cause bleeding and clotting abnormalities, though the exact mechanism for this is not yet fully understood.  

Inherited platelet disorders 

Again, dogs can be born with platelet issues either causing reduced numbers (such as cyclic haematopoiesis found in grey collies), or abnormal function (such as canine thrombopathia in Bassett Hounds).   

Von Willebrand’s disease  

Perhaps the most well-known hereditary platelet issue in dogs. This condition is common in many breeds including Dobermann Pinscher’s, German Shepherds, Gold Retrievers, Standard Poodles and Shetland Sheepdogs. Affected dogs are deficient in von Willebrand’s factor, a protein that carries an important clotting factor (factor VIII). There are three different types of von Willebrand’s disease, so some dogs may only have mild symptoms whereas others can have more severe signs.  

Acquired platelet disorders  

These are generally more common than hereditary ones. They can be caused by: 

Rickettsial diseases  

Infections with organisms like Ehrlichia and Anaplasma can cause varying degrees of platelet loss in dogs. Ticks are usually the underlying cause of infection, passing these organisms on when they move from an infected host to a new one.  

Immune system dysfunction  

The immune system can malfunction and produce antibodies that attack the body’s own cells. This leads to a lack of production or the destruction of platelets. This is called immune mediated thrombocytopaenia (IMTCP), and sometimes happens alongside immune-mediated anaemias, when it is sometimes known as Evans’ Syndrome. 

Drug reactions  

Some drugs can suppress the production of platelets by the bone marrow, causing a reduced number in the body. Other drugs may deactivate platelets already in the bloodstream directly, for example, aspirin.  

Cancer  

Some types of cancer can trigger DIC (mentioned earlier). Abnormal bleeding can occur in cancer patients due to this, but also abnormal platelet function and inflammation of blood vessels. 

Blood vessel disorders 

Defects in the blood vessels themselves can cause clotting issues.  

Ehlers-Danlos syndrome  

Known as “rubber puppy disease” or “cutaneous asthenia”, this occurs due to a defect in the animal’s connective tissue. This rare issue is present from birth. Affected dogs have characteristically loose skin that tears easily, as well as being prone to bruising. 

Rocky Mountain Spotted Fever  

This is a disease caused by a rickettsial organism that is transmitted via tick bites. This organism causes swelling of the blood vessels and bleeding. Symptoms can include nosebleeds, bruising, bleeding at the back of the eye and blood in the urine or faeces. As the name suggests, this is primary considered a US disease and is not typically seen in Europe. 

Canine Herpes Virus  

This virus affects puppies that are 7 – 21 days old causing inflammation and destruction of blood vessels. Death usually occurs within a day of symptoms being seen. 

What are the symptoms of a clotting disorder in dogs? 

A dog with a clotting disorder may have some or all of the following symptoms, depending on their underlying disease –  

How is a clotting disorder diagnosed in dogs? 

Your vet will start by discussing your pet’s symptoms and performing a physical examination. They will check their hydration status, assess their gum colour and look at their demeanour. They will check things like your dog’s heart rate, breathing rate and temperature. Close attention may be paid to things like bruising, joint pain or bleeding. 

They may ask you questions about your dog’s care including whether they could have had access to anticoagulants such as rodent bait or had any recent tick bites. 

Depending on their findings they may suggest further tests. These could include – 

• Complete Blood Cell count – a blood test that run on a machine assess your dogs, red cell, white cell and platelet numbers. Packed cell volume (PCV) and total solids (TS) may also be measured to give more information about anaemia. 

• Manual platelet count and cytology – for a more accurate measure of platelets a blood smear is often examined for a manual platelet count. This also allows the appearance of the blood cells to be checked over too.  

• Biochemistry – a blood test that assesses your pet’s organs such as their liver and kidneys, as well as protein and blood sugar levels.  

• Buccal mucosal bleeding time (BMBT) – a small cut is made on your dog’s gum and monitored to see how long it takes to clot. 

• Prothrombin (PT) and partial thromboplastin time (PTT) tests – specialised blood tests may also be required to assess how quickly the blood clots.  

• Clotting factors – a blood sample which is usually sent to a laboratory to assess the clotting factors that are present in your dog’s bloodstream, looking for any deficiencies e.g. a Von Willebrand factor assay.  

• Diagnostic imaging – Ultrasound and X-rays, or even more advanced imaging like a CT scan, may be required if your vet is suspicious of underlying liver disease or cancer. Samples of cells or tissue might be taken for further analysis. 

You vet will talk you through the tests that are relevant to your dog. Don’t hesitate to ask questions if you are unsure or need a procedure explaining further.  

What is the treatment for a clotting disorder in dogs? 

The treatment for a clotting disorder will very much depend on the underlying disease process as well as how your dog presents to the veterinary practice. 

For example, a dog that presents with severe bleeding may be in shock and could require hospitalisation for intravenous fluids and a blood transfusion. 

If caught early enough, rodenticide poisoning can be successfully treated by inducing vomiting and administering an antidote – vitamin K supplementation. 

Infectious tick-borne diseases can also be treated with courses of anti-parasite treatment and antibiotics. Intravenous fluids and blood transfusions may be needed in some cases too.  

Other diseases such as liver failure and inherited coagulopathies can be more challenging and some of these conditions can be life-limiting. Dogs with inherited coagulopathies will need to avoid surgery and could need blood product transfusions should a major trauma occur.  

Your vet will explain the treatment plan and prognosis based on their findings.  

Summary 

Clotting disorders can be a complicated area of veterinary medicine as there are various levels at which problems can occur. If your vet is suspicious of a clotting disorder, then they may need to run some tests to understand the severity and underlying reasons for your dog’s problem. If your dog is showing concerning symptoms like prolonged bleeding from a wound, nosebleeds, blood in their stools or urine or bruising, then take them to a vet as soon as possible. If your pet may have consumed a rodenticide product then don’t wait to see if any of these symptoms develop – get them seen immediately. The sooner your dog is treated the better the outcome is likely to be.