Low platelets in dogs (i.e. thrombocytopenia in dogs) can be a symptom of many conditions—some more serious than others. Integrative veterinarian Dr. Julie Buzby explains the symptoms, causes, diagnosis, treatment, and prognosis for low platelets in dogs. Armed with this information, you will know what to expect should your dog have a low platelet count.
It’s not unusual for me to wake up to a random bruise on my knee or shin. Busy clinic life just seems to lend itself to knocking my knees on the edge of an exam table or hitting my shins on open cage doors.
If you are like me, and you wake up with a mysterious bruise, generally there is no need to panic. But did you know that mysterious bruises in our beloved canine companions are much less common, and something you shouldn’t ignore?
Bruises are not always related to a significant underlying health problem. But, finding one or more bruises on your furry family member can be a sign of low platelets in dogs.
What are platelets and why are they important?
Platelets are one of the three main cell types produced in the bone marrow, along with red blood cells and white blood cells. Out of the three cells lines, platelets tend to be like the demure supporting actor. They stay out of the limelight, but they play an incredibly important role—helping the blood clot. Platelets are like little disc-shaped cellular Band-Aids that rush to the scene of an injury and help form a protective plug to stop the bleeding.
And platelets don’t just help stop the dramatic bleeding from gashes or surgery. They also prevent the constant tiny bits of bleeding that would occur from the daily wear-and-tear to all the blood vessels in the body. Without platelets, these inconspicuous micro-injuries would lead to devastating bleeding throughout the body.
Low platelets in dogs
The scientific term for low blood platelets is thrombocytopenia. It is important to remember that thrombocytopenia is a symptom, rather than a diagnosis. There are many possible causes of low platelets. To determine the best course of treatment, it is crucial to identify and address the underlying cause.
But prior to jumping into the causes of thrombocytopenia in dogs, you need to know some background information. First let’s talk a little bit about what “low platelets” means in a practical sense. And then we will get to the signs you might see if your dog has thrombocytopenia.
What is thrombocytopenia (i.e. low platelets) in dogs?
A piece of good news related to low platelets in dogs is that the platelet count must drop substantially below normal before causing serious problems. The normal platelet count in dogs ranges from 200,000-500,000 platelets per microliter. This means there are many extra tiny disc-shaped “Band-Aids” available to rush to the scene of troublesome bleeding and save the day.
When platelet numbers drop somewhere below about 100,000 platelets per microliter, the risk of bleeding after an injury, medical procedure, or surgery increases substantially. And the platelet count must drop even lower—below 30,000-40,000 platelets per microliter— before you see spontaneous signs of bleeding.
It is great that there is some cushion built into the system. But this also means that your dog’s platelet numbers can be silently dropping without you knowing there is anything wrong. In fact, it is not unusual for your veterinarian to pick up a low platelet count on routine screening lab work. Often this happens before the thrombocytopenia starts causing any problems that even the most vigilant dog parent would notice.
What are the symptoms of low platelets in dogs?
Once the platelet count is low enough to cause spontaneous bleeding, all of the dog’s symptoms come from two problems:
- Bleeding in a particular location
- Low red blood cell count (i.e. anemia in dogs) due to the bleeding
If you notice any of the symptoms outlined below, and especially if you notice more than one of them, take your dog to the veterinarian as soon as possible.
Symptoms that are related to bleeding in a particular location
Sometimes you may notice signs that your dog is bleeding somewhere, including:
Bruising
Dogs with low platelets bruise more easily, and they can even bruise with no inciting injury. These bruises might appear as dark reddish-brown or purple patches (i.e. ecchymoses) or small pinprick red spots (i.e. petechiae).
These bruises are often most visible on areas with less hair, like the inside of a dog’s ears or on the hairless portion of the belly. You can also sometimes notice red splotches on the white portions of the eyes, or on the gums and/or tongue.
Nose bleeds
Thrombocytopenia can cause spontaneous dog nose bleeds, which may appear as blood dripping from one or both nostrils. While nosebleeds can be normal in people and not related to an underlying medical issue, this is not the case with dogs. If your dog has a nosebleed, this warrants a visit to your veterinarian.
Bleeding gums
If you notice your dog’s gums bleeding, it may just be related to severe dental disease in dogs. But it also could be a sign of a low platelet count. Dogs with severe thrombocytopenia might have bleeding from their gums when they eat. Or you might notice blood on their toys and bones or bloody drool.
Gastrointestinal (GI) bleeding
The gastrointestinal tract is one of the more common sites of bleeding in dogs with very low platelet counts. This can mean bright red blood in the stool if the source of the bleeding is lower down in the colon or rectum. Or the stool can look tarry or black if the bleeding is in the stomach or small intestine. Bleeding from the stomach can also cause the dog to vomit up black specks that look like coffee grounds.
Bloody urine
Dogs with a low platelet count can also bleed from the lining of their bladder, causing red or brown urine. It is important to note that there are other less worrisome causes of bloody urine, including a run-of-the-mill urinary tract infection (UTI in dogs). But regardless of the cause, bloody urine should earn your pup a ticket for a prompt veterinary visit.
Excessive bleeding
Dogs with thrombocytopenia may also experience prolonged bleeding from minor cuts or wounds.
Symptoms due to anemia from blood loss
Additionally, low platelets are one of the causes of anemia in dogs. Therefore, you may see signs that are related to the low red blood cell count, including:
Pale or white gums
Any area on your pup that is normally pink or red can become pale, or even white, when the red blood cell count is very low. If you ever notice that your canine companion’s gums or tongue are white, this is a medical emergency.
Rapid heart rate
The heart tries to compensate for a low red blood cell count by pumping harder and faster. You might notice this as a rapid heartbeat that you can feel, or even see, on the outside of the dog’s chest.
Rapid breathing
Without enough red blood cells, your dog’s organs are not able to get sufficient oxygen. To compensate for this, you might notice your dog breathing faster or harder than normal.
Lethargy
Your dog might appear tired and less energetic than usual. Lethargic dogs may be reluctant to go on their normal walk or they may seem less interested in playing.
Weakness or collapse
In severe cases, dogs with extremely low platelet and red blood cell counts may be weak or even collapse.
Take your dog to the vet when you see signs of low platelets
Almost all of these symptoms can be caused by other health issues. So if you observe any of these signs in your dog, the first step is to consult your veterinarian. Early diagnosis and appropriate treatment can help your pup get back to his or her happy and healthy self.
How will your vet diagnose your dog with low platelets?
If you end up in your veterinarian’s office for any of the signs discussed above, knowing what to expect can help ease some of your understandable anxiety. Diagnosing low platelets in dogs involves a series of steps that veterinarians use to understand what is happening with the dog’s platelet count. Let’s break it down into the main diagnostic process:
1. Evaluating the dog’s history and symptoms
When you get to the veterinarian’s office, a member of the veterinary team will perform a brief exam. This is a quick way to determine if your dog is stable, or if the situation warrants more urgent evaluation and care.
If your dog is stable, your veterinarian, or the veterinary nurse, will ask you about your pup’s medical history. This may include the symptoms you are seeing, and any recent illnesses, medications, or other changes in behavior or health you have noticed at home.
But should your dog’s condition require immediate intervention, the veterinarian may start to stabilize your dog while another team member discusses your dog’s medical history with you.
2. Performing a physical examination
After getting a history, your veterinarian will conduct a thorough physical examination. He or she will check for any signs of bruising, bleeding, or abnormalities that might indicate low platelets. And the vet will also be looking for any changes that might point toward other causes of your dog’s symptoms.
3. Evaluating a complete blood count (CBC)
The initial diagnostic test for low platelets is the complete blood count (CBC). This test measures the levels of the different cell types within dog’s blood, including the number of red blood cells, white blood cells, and, of course, platelets.
If the platelet count is normal, your veterinarian will start investigating what else might be causing your pup’s clinical signs. But if the CBC reveals a low platelet count, your vet will move on to the next step in the process.
4. Performing a blood smear examination
Platelets are sticky little guys. This helps them do their job and stick to the site of injuries to prevent bleeding. But it also means that sometimes they can stick together so the blood analyzer cannot accurately measure the platelet count. This may lead to a false low platelet count in dogs.
If the platelet count is low on the CBC, it is always a good idea to confirm if this is a real finding with a blood smear examination. To perform a blood smear, your veterinarian will spread a drop of blood thinly on a glass slide. Then he or she will examine this slide under a microscope to see if the platelet count is truly low, or if there are lots of sneaky giant platelet clumps falsely lowering the machine count.
5. Selecting the appropriate additional diagnostic tests
Low platelets are just a symptom of a bigger problem. And your vet’s end goal is to understand the underlying cause of your pup’s thrombocytopenia. To do this, he or she will probably suggest additional tests. These could include:
- Blood chemistry tests
- Blood testing for infectious diseases
- Imaging tests like X-rays and ultrasound
- Evaluating a bone marrow sample (e.g. bone marrow aspirate or biopsy)
Which of these tests your vet starts with will depend on what he or she suspects the underlying cause of the low platelets might be.
What causes low platelets in dogs?
Before we jump into the individual causes, I think it is useful to zoom out and look at the bigger picture. If your dog’s platelet count is low, there are really only three overarching reasons this might be the case:
- The bone marrow is not making enough platelets
- Platelets are being destroyed somewhere in the body
- Platelets are being lost, used up, or are hiding somewhere other than in the bloodstream
This sounds simple. But when you zoom back in, lots of specific medical conditions fall into each of those big categories. And to make things even cloudier, some conditions lower platelets by more than one of those overarching mechanisms.
Now that you have an idea of what the big picture looks like, let’s take a look a some of the more common causes of low platelets in dogs.
Breed-related causes
Macrothrombocytopenia is a mouthful of a name that means giant platelets. This condition has been documented in several breeds of dogs. Most notable is the Cavalier King Charles Spaniel (CKCS), where idiopathic thrombocytopenia is an autosomal recessive trait. But it has also been documented in Norfolk Terriers and Cairn Terriers.
Dogs with macrothrombocytopenia have a decreased number of platelets overall, but the platelets they do have are super-sized. The happy news is that their giant platelets seem to get the job done. And affected dogs tend to not have any negative repercussions from their low platelet counts—which can range from 30,000 to 150,000 platelets per microliter.
Greyhounds also often have slightly lower platelet counts than other breeds. The cause of this is unknown and they too are generally asymptomatic.
Immune mediated thrombocytopenia
Sometimes, your dog’s immune system mistakenly identifies the platelets as “bad guys” and attacks them, reducing their numbers. This condition is known as immune mediated thrombocytopenia (ITP in dogs). It is one of the more common causes of severely low platelets in dogs and may also cause an enlarged spleen in dogs.
Infections
Certain viral, bacterial, and tick-borne infections can all decrease the platelet count. They may either reduce the production of platelets or trigger the immune system to destroy platelets (which may also lead to an enlarged spleen). Some infections that can cause low platelet counts are:
- Tick-borne disease in dogs such as Ehrlichiosis, Anaplasmosis, Rocky Mountain Spotted Fever, and Babesiosis
- Bartonella
- Leptospirosis
- Parvovirus
- Distemper
- Heartworm disease in dogs
- Systemic fungal infections
Cancers
Cancers like lymphoma in dogs and hemangiosarcoma in dogs can trigger the immune system to attack platelets and lead to secondary ITP. And leukemia, lymphoma, and multiple myeloma can crowd out the normal cells in the bone marrow, leading to decreased production of platelets.
Bone marrow diseases
Since the bone marrow is the “platelet factory” where platelets are produced, anything that negatively affects how the bone marrow functions can decrease platelet production and lead to low platelet counts. Bone marrow disease is another one of those overarching categories.
Several types of bone marrow disease can lead to low platelets, including:
- Cancer within the bone marrow (as noted above)
- Immune-mediated disease at the level of the bone marrow
- Scarring or fibrosis of the bone marrow (which can occur secondary to some medications and infections)
Medications
Certain medications can cause low platelet counts in dogs, although this is a relatively rare medication side effect. Below are some types of medication that have been associated with thrombocytopenia in dogs:
Certain antibiotics
Some antibiotics, especially certain types of penicillin, cephalosporin, and trimethoprim-sulfonamide combination antibiotics have been known to trigger immune-mediated destruction of platelets. Rifampin, an uncommonly used antibiotic, has also been linked to low platelet counts in dogs.
Chemotherapy drugs
Some chemotherapy medications used to treat cancer in dogs can suppress bone marrow activity, affecting the production of platelets. However, it is much more common for chemotherapy medications to lead to low white blood cell counts than it is to lead to low platelet counts.
Estrogen-containing medications
Estrogen-containing medications, either administered as prescribed, or consumed by your pup accidentally, can sometimes lead to bone marrow damage and thrombocytopenia. This is especially true at high doses.
Talk to your vet about medication concerns
It’s important to note that not all dogs will experience low platelet counts when taking the medications we just discussed. In most cases, the benefits of these drugs outweigh the potential risks. Your veterinarian will carefully consider the specific medical needs of your dog before prescribing any medication. But if you have concerns about your dog’s medications or notice any unusual symptoms, always consult with your veterinarian for further evaluation and guidance.
Snake bites
When a venomous snake bites a dog, the venom can lead to clotting abnormalities and low platelet counts. The venom of these snakes contains toxins that can disrupt the normal blood clotting process and lead to bleeding disorders. Some of the snake species that are known to potentially cause thrombocytopenia in dogs include:
- Rattlesnakes
- Cottonmouths (also known as Water Moccasins)
- Copperheads
- Vipers
Disseminated intravascular coagulation
Disseminated intravascular coagulation (DIC), is a serious medical condition that can occur in dogs (and humans too) secondary to infections, toxins, cancers, severe inflammation, or other serious illnesses.
Whatever the underlying cause, the consequence of DIC is that the normal clotting mechanisms go haywire. This leads to lots of tiny blood clots forming inside the blood vessels all over the body. And when these tiny clots form, they use up all the platelets and clotting proteins quickly, leading to thrombocytopenia.
What is the treatment for low platelets in dogs?
Now that you know about the potential causes of low platelets, you are probably wondering what options your veterinarian has for treating the causative condition and your dog’s low platelets. Your vet will need to tailor a unique treatment plan to fit your pup’s needs based on the severity of the thrombocytopenia and the underlying cause.
This plan will include:
- Treatment of the underlying disease and/or withdrawal of any potential triggering agents
- General supportive care
- Emergency control of bleeding and/or correction of severe anemia (if needed)
Let’s quickly look at each of those tactics.
Prescribing or withdrawing medications
Your veterinarian may prescribe medications to treat whatever condition he or she has diagnosed your dog with. For example, if an immune-mediated disorder is the cause of the low platelets, the vet may prescribe immunosuppressive drugs to regulate the immune system. Or the vet may use antibiotics to eliminate an infection or chemotherapy medications to target cancer.
On the other hand, if certain medications might be causing the low platelet count, your veterinarian may recommend discontinuing or adjusting those medications to see if your dog’s platelet count improves.
Supportive care
While addressing the underlying cause, your dog may need supportive care. This can include:
- Anti-nausea medications like Cerenia for dogs
- Pain medications
- IV fluids
- Rest
- Limiting physical activity that might lead to injuries
- Avoiding situations that may lead to bleeding
Transfusions
Dogs with very low platelets can sometimes experience significant enough blood loss that they need a blood transfusion.
Packed red blood cell transfusions are the most common type of blood transfusions performed in veterinary medicine. These transfusions don’t provide any platelets or stop the bleeding. Instead, they are aimed at stabilizing the patient. This buys more time for other treatment options to take effect and improve the platelet count.
Whole blood transfusions are another option to help with anemia and ongoing life-threatening bleeding. While whole blood contains both red blood cells and platelets, the platelets don’t survive for very long in circulation. This means they may temporarily help with severe bleeding, but the effect is short-lived.
Although the original problem was low platelets, veterinarians uncommonly administer platelet transfusions, even in dogs with severe thrombocytopenia. This is the case due to limitations in the availability of effective platelet products for dogs.
What is the prognosis for dogs with low platelet counts?
In general, dogs with low platelet counts can have a range of outcomes. A Cavalier King Charles Spaniel with macrothrombocytopenia has a great prognosis and will suffer no ill effects from a low platelet count.
On the other hand, the prognosis for the rest of the dogs with low platelets will depend on how low the platelet count is, the underlying cause of the low platelet count, and how the individual dog responds to treatment.
If the low platelet count is mild, or even moderate, and there are no significant clinical signs, the prognosis is usually favorable. With appropriate treatment and management of the underlying cause, many dogs can recover fully and lead a normal, healthy life.
However, severe thrombocytopenia, especially when accompanied by significant bleeding or other complications, can be life-threatening. The prognosis becomes more guarded in these cases. And immediate and aggressive treatment is crucial. Dogs with severe thrombocytopenia may require hospitalization and intensive care.
How can you prevent thrombocytopenia in dogs?
With all this talk of the dangers of low platelets, you may be wondering if there is anything you can do to keep your dog safe. Not all cases of thrombocytopenia can be prevented. But there are steps you can take to promote your dog’s overall health and decrease the risk that your dog might be negatively affected by a low platelet count.
Diligent use of flea, tick, and heartworm preventives can help prevent causes of thrombocytopenia like flea and tick-borne diseases or heartworm disease. And routine check-ups with your veterinarian can allow him or her to detect early signs of health issues, including low platelet counts, before your dog is outwardly showing signs of illness.
Work with your veterinarian
Remember, though, that while taking these preventive measures can reduce the risk of low platelet counts, some factors are just beyond your control. If you do notice any unusual symptoms or signs of illness in your dog, the most important thing you can do is to promptly consult your veterinarian for guidance.
The sooner you detect the problem the better, which is why I always recommend dog parents doing a weekly at-home examination of their dogs. You can learn the basics in my article on the 5-Minute Dog Wellness Scan. Or for a more in-depth explanation (complete with videos), check out my master course, Dr. Buzby’s Tip-To-Tail Health Scan™.
Luckily, with early diagnosis (thanks in part to you recognizing the problem or bringing your dog in for regular wellness visits) and prompt treatment, many dogs with low platelet counts have an excellent chance of recovering and living a normal, healthy life. Hopefully if your dog has low platelets, the vet will be able to find and treat the cause easily. And your dear canine companion will be on the road to recovery before you know it.
Has your dog ever been diagnosed with low platelets in dogs?
Please feel free to share his or her story below.
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