The word ‘thrombocytopenia’ means too few platelets. Since platelets are crucial for the blood to clot, too few can lead to spontaneous bleeding or bruising. Here’s what you need to know about this potentially life-threatening condition.
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What is thrombocytopenia?
Thrombocytopenia means too few platelets in the bloodstream. Platelets help to form blood clots, which slow or stop bleeding and allow wounds to heal. When there are too few platelets in the blood, this can cause uncontrollable bleeding from wounds, and spontaneous bleeding and bruising.
Causes of thrombocytopenia in dogs
So, why would a dog have thrombocytopenia? Thrombocytopenia can be present from birth (although thankfully this is rare) or, more commonly, acquired later in life. When it is acquired, too few platelets can be caused by:
- Excessive loss of platelets (such as following severe bleeding)
- Lack of production of platelets (in the bone marrow, for example due to cancer)
- Destruction of platelets (the body attacking its own platelets, due to immune-mediated disease)
Several conditions can cause thrombocytopenia, including:
- Immune-mediated diseases, where the body attacks its own platelets, such as Immune Mediated Thrombocytopenia (IMTP or IMT)
- Cancer
- Toxins, such as xylitol or zinc (which are poisonous to dogs)
- Infectious diseases, such as parvovirus
- Some parasites (although this is rare in the UK)
Some medications can also cause thrombocytopenia as a side effect, especially at very high, prolonged doses or overdoses. However, the most common cause of thrombocytopenia in dogs is Immune mediated thrombocytopenia, IMTP. This can sometimes be found along with Immune mediated haemolytic anaemia (IMHA), and when combined, this is known as Evans’ Syndrome.
Symptoms of thrombocytopenia in dogs
The signs of thrombocytopenia can be subtle initially, until the platelets drop further and then the symptoms are dramatic. Signs of thrombocytopenia include:
- Unexplained bruises (ecchymoses)
- Small red spots on the gums or skin (petechiae) – like in the photo at the top
- Blood in the urine or stools
- Vomit containing blood
- Bleeding from the nose or mouth
- Decreased appetite
- Lethargy (sleepiness or lack of energy)
- Pale gums
- Rapid breathing
- Collapse
Of course all of these symptoms can have many other causes, so it’s important that you consult your vet straight away if you notice any in your dog.
How is thrombocytopenia diagnosed in dogs?
Thrombocytopenia can be diagnosed using blood tests, which look at the platelet count, clotting times and if there are enough red blood cells (i.e. testing for anaemia). The blood tests will also look at the health of some body organs.
Your vet will also investigate for the underlying cause of the thrombocytopenia. The investigations would be tailored by their suspicions from the questions they’ve asked you and their physical exam of your dog. These could include urine tests, more blood tests, x-rays, ultrasound, CT scans and bone marrow aspirates. A diagnosis of primary IMTP (which means it isn’t caused by another disease or medical condition and is happening on its own) is made by excluding other possible causes.
Treatment
Treatment of thrombocytopenia in dogs will depend on the cause. In some cases, such as severe anaemia (low red blood cells), a blood transfusion may be needed. Another option, if the platelets are low but the red blood cell numbers are normal, is to give plasma which is rich in platelets. These measures are often used to stabilise the patient while carrying out investigations for a diagnosis.
If an underlying cause for it can be found, such as an infection, then this will need to be treated. Some underlying causes are harder to treat than others, such as cancer.
Immune-mediated thrombocytopenia is treated with immune-suppressant drugs, usually steroids, to suppress the overactive immune system and reduce its destruction of platelets. Sometimes additional immune suppressants are needed, on top of the steroids. Some dogs can be weaned off treatment after around six months, especially if an underlying cause has been found and treated. However, sometimes dogs need low dose treatment for life, and may suffer flare ups.
Can thrombocytopenia in dogs be cured?
If the underlying cause can be found and is treatable, then dogs can make a full recovery with treatment. Some causes, such as cancer, are much harder to treat. Primary immune-mediated thrombocytopenia can require life-long therapy. Sadly, severe cases of thrombocytopenia can be fatal.
Summary
Thrombocytopenia is a condition in which the platelet numbers are too low, causing spontaneous bleeding and bruising. It is often caused by an immune-mediated condition, meaning an overactive immune system, which attacks and destroys platelets. Prompt diagnosis and treatment are really important for a positive outcome, so if you have any concerns about your dog, it’s best to get them to a vet sooner rather than later.
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Further Reading:
- Platelet Disorders in Animals – Circulatory System – MSD Veterinary Manual
- Xylitol toxicosis in dogs
- Toxicology Brief: Too much of a good thing: Zinc toxicosis in dogs
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