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Immune Mediated Anemia

The immune system in a dog is made up of a collection of specialized cells, proteins, tissues, and organs, which all constitute a solid defense system against a variety of infections, including bacterial, fungal, parasitic, and viral infections. Antibodies are proteins secreted by specific cells of the immune system, which bind to foreign substances, known as antigens, to destroy them. A diseased condition arises when the body’s immune system mistakenly starts recognizing its own red blood cells (RBCs) as antigens and initiates their destruction. In this process antibodies produced by the immune system bind to the RBCs and destroy them. The hemolysis (destruction) of red blood cells results in the release of hemoglobin, which can lead to jaundice, and further on to anemia when the body cannot produce enough new red blood cells to replace the ones being destroyed. This is why this disease is also known as immune-mediated hemolytic anemia, or IMHA.

The most commonly affected breeds include Irish setters, poodles, English springers, cocker spaniels, collies, and Doberman pinschers. In some breeds hereditary factors are suspected to be responsible but no genetic basis is yet established. These breeds include the Vizsla, Scottish terrier, cocker spaniel, miniature schnauzer, and old English sheepdog. This disease has been reported in dogs within the ages of 1-13 years. Female dogs are found to be at higher risk than males.

Symptoms and Types

• Weakness
• Lethargy
• Poor appetite
• Fainting
• Exercise intolerance
• Vomiting
• Rapid breathing
• Diarrhea
• Increased thirst and urination in some dogs
• Fever
• Jaundice
• Rapid heart rate
• Melena (Black feces due to hemorrhage in gastrointestinal tract)
• Petechia (red, purple spots on the body due to minor hemorrhages)
• Ecchymoses (skin discoloration in patches or bruises)
• Joint pains

Causes

• Autoimmune hemolytic anemia (production of antibodies against the body’s own RBCs and their destruction)
• Systemic Lupus Erythematosus (SLE) (production of antibodies against the body’s own tissues and blood)
• Certain infections like ehrlichia, babesia, and leptospria infections
• Certain drugs, like antibiotics
• Vaccination
• Heartworm disease
• Neoplasia (tumor)
• Neonatal isoerythrolysis (destruction of the red blood cells [erythrocytes] within a puppy's body system by the action of maternal antibodies)
• Dysregulated immune system
• Idiopathic (unknown cause)

Diagnosis

Your veterinarian will perform a detailed and complete physical examination, with laboratory tests, including complete blood tests, biochemical profile and urinalysis. These tests provide valuable information to your veterinarian for the preliminary diagnosis of the disease. More specific testing may be required to confirm the diagnosis and to find the underlying cause in case of secondary IMHA. X-ray images will be taken to evaluate the thorax and abdominal organs, including the heart, lungs, liver, and kidneys. Echocardiography and ultrasound studies may be used in some animals. Your veterinarian will also take bone marrow samples for specific studies related to the development of RBCs.

Treatment

In acute cases, IMHA can be life-threatening condition requiring emergency treatment. In such cases your dog will be hospitalized. The primary treatment concern will be to stop the destruction of further RBCs and stabilize the patient. Blood transfusions may be required in cases where extensive bleeding or profound anemia is present. Fluid therapy is used to correct and maintain the body's fluid levels. In those cases that do not respond to medical treatment, your veterinarian may decide to remove the spleen to protect your dog from further complications. Your dog's progress will be monitored and emergency treatment continued until it is completely out of danger.

Living and Management

Strict cage rest may be required while your dog is stabilizing. Some patient respond well, while for others, long-term treatment is required; some dogs may require life-long treatment. Emergency treatment will be continued until your dog is completely out of danger. After successful treatment, your veterinarian will schedule follow-up visits every week in the first month, and later, every month for six months. Laboratory testing will be performed at each visit to evaluate the status of the disease. If your veterinarian has recommended life-long treatment for your dog, 2‒3 visits per year may be required.