Understanding Polycythemia in Dogs: Causes, Symptoms & Treatment

Polycythemia in dogs is a rare but serious blood disorder that causes an excessive increase in red blood cells (RBCs), thickening the blood and potentially affecting overall health. This condition can impair oxygen delivery, making prompt recognition and treatment essential for your dog's wellbeing. There are three main types: relative, transient, and absolute polycythemia, each with distinct causes and implications.

Types of Polycythemia in Dogs

1. Relative Polycythemia

Relative polycythemia occurs when a dog’s plasma volume decreases, often due to dehydration from vomiting, diarrhoea, or inadequate water intake. This fluid loss makes the concentration of red blood cells appear elevated without an actual increase in their number. It is important to address the underlying cause, such as dehydration, to restore balance.

2. Transient Polycythemia

This temporary form happens when the spleen contracts in response to stress, excitement, seizure activity, or restraint, releasing stored red blood cells into circulation. Transient polycythemia is usually short-lived and rarely leads to symptoms that require treatment.

3. Absolute Polycythemia

Absolute polycythemia describes a true increase in red blood cells and is subdivided into:

• Primary Absolute Polycythemia (Polycythemia Vera): A rare myeloproliferative disorder where bone marrow independently produces excessive red blood cells regardless of erythropoietin (EPO) levels. This can cause persistently thickened blood, increasing the risk of clotting and complications affecting the heart and brain.
• Secondary Absolute Polycythemia: Occurs due to increased erythropoietin production caused by chronic low oxygen levels (hypoxia), heart or lung disease, high altitude, or tumours secreting EPO. The body attempts to compensate for poor oxygen delivery by producing more red blood cells.

Recognising Symptoms of Polycythemia

Symptoms often become apparent once the packed cell volume (PCV) exceeds 65%, though some breeds, such as Greyhounds, naturally have higher PCV. Watch for signs including:

• Lethargy and exercise intolerance
• Weakness or sudden lack of energy
• Bleeding events such as nosebleeds, bloody vomiting, or black tarry stools
• Neurological symptoms: seizures, behavioural changes, tremors, blindness, or poor coordination
• Reddening or bluish discoloration of gums
• Excessive thirst and increased urination
• Swollen abdomen or respiratory difficulties

Causes Behind Polycythemia

Understanding the cause is vital for effective treatment:

• Relative polycythemia: Dehydration due to vomiting, diarrhoea, or insufficient water intake
• Transient polycythemia: Stress, excitement, seizures, or restraint that cause splenic contraction
• Primary absolute polycythemia: Rare bone marrow disorders producing too many red blood cells, often inherited or spontaneous mutations
• Secondary absolute polycythemia: Underlying conditions such as chronic lung or heart disease, high altitude exposure, kidney disorders, tumours affecting EPO secretion, or hormone imbalances

Diagnosing Polycythemia in Your Dog

A thorough veterinary examination is required to diagnose and classify polycythemia accurately. The vet will:

• Review your dog’s medical history and symptom onset
• Perform physical examination focusing on mucous membrane colour and hydration status
• Recommend blood tests including complete blood count (CBC) and chemical profiles to evaluate RBC levels and rule out other diseases
• Urinalysis and electrolyte panels
• Utilise imaging techniques such as X-rays and ultrasounds to detect underlying causes like tumours or organ abnormalities
• Measure blood oxygen and erythropoietin levels
• Possibly perform a bone marrow biopsy for suspected primary polycythemia vera cases

Treatment Strategies for Polycythemia

Treatment varies according to type and severity:

• Relative polycythemia: Soften blood concentration by rehydrating the dog through intravenous fluids and addressing the cause of dehydration
• Primary polycythemia vera: Requires regular phlebotomy, a safe blood removal procedure to reduce RBC levels and prevent complications; medications such as hydroxyurea may reduce RBC production; oxygen therapy might be necessary for low oxygen symptoms
• Secondary polycythemia: Focuses on treating underlying diseases such as heart or lung conditions or tumour removal

Living with a Dog Diagnosed with Polycythemia

Ongoing veterinary care is vital. Schedule routine check-ups to monitor red blood cell levels and adjust treatment as needed. Early veterinary intervention if symptoms return can vastly improve quality of life. Be vigilant for signs of worsening condition, including neurological changes or bleeding, and seek prompt professional advice.

Responsible pet ownership, including regular vet visits and maintaining proper hydration, can help manage polycythemia effectively and support your dog's wellness.

FAQs: What do I need to know about polycythemia in dogs?

Is polycythemia in dogs treatable? Yes. With early diagnosis and proper veterinary care including phlebotomy and treatment of any underlying causes, many dogs can live comfortable lives.

Can dehydration cause polycythemia? It can cause relative polycythemia by concentrating red blood cells due to lowered plasma volume.

Are certain breeds more prone? Some breeds normally have higher RBC counts, but polycythemia vera is rare across all breeds. Middle-aged females may be more affected.

What is phlebotomy? A safe veterinary procedure gently removing excess blood to lower red blood cell levels and reduce blood thickness.

Find a Puppy Responsibly for Your New Best Friend

If you're considering bringing a puppy into your home, ensure you find your new furry friend through reputable breeders or adopt from trustworthy rescue organisations. Responsible breeders will prioritise health screening and ethical practices to support your dog's long-term health.

Remember, timely veterinary intervention and informed care are the best ways to help dogs with polycythemia lead happy, healthy lives.