Anemia is an inadequate number of red blood cells, or erythrocytes, in the circulatory system. Erythrocytes carry life-sustaining oxygen to the body tissues. Without them, tissues become starved for oxygen, and weakness and tissue damage set in.
Causes of anemia fall into three categories: blood-loss anemia, early destruction of erythrocytes, and lack of erythrocyte production. Treatment varies depending on the cause.
Risk factors and detection
Some dogs inherit breed-related blood disorders—enzyme deficiencies, hemophilia, and clotting factor deficiencies—that can lead to anemia. Free-roaming dogs can develop anemia from traumatic injuries, toxin ingestion, or infectious diseases. Dogs with such chronic diseases as kidney failure or liver disease also may develop anemia.
Blood-loss anemia
Blood-loss anemia can be sudden (acute) or occur over time (chronic). Acute causes include traumatic injuries, such as being hit by a car; inherited clotting deficiencies; and rodenticide poisoning. Chronic blood-loss anemia can result from gastric ulcers, intestinal parasites, cancer, bleeding through the urinary tract, and fleas.
Early destruction of erythrocytes
Several conditions can shorten erythrocyte life span and cause anemia, including inherited enzyme abnormalities, blood parasite infestations, viral infections, certain drugs zinc toxicity caused by swallowed pennies or zinc bolts, and an abnormal immune system attack on the body's red blood cells.
Lack of erythrocyte production
Causes of inadequate erythrocyte production by the bone marrow include iron deficiency, either from chronic blood loss or poor diet, and conditions that suppress the bone marrow. These conditions include chronic kidney or liver disease; other chronic illnesses andvarious cancers. Chemotherapy drugs, estrogen, chemicals, heavy metals, and other toxins also impair erythrocyte production.
Signs of anemia include:
- decreased appetite
- fatigue or weakness
- blackish feces
- weight loss
- bloody urine
- pale or jaundiced gums and tongue
- weak pulse
- heart murmur
- collapse.
Call your veterinarian if you notice any of these signs. Your veterinarian will ask if your dog has been exposed to toxins, is receiving any medications, or has traveled recently. He or she will perform a complete physical examination and may order blood tests, fecal tests, a urinalysis, X-rays, and possibly a bone marrow aspirate or biopsy to determine the condition's cause and severity.
Prevention and treatment
You can't ward off all types of anemia, but a balanced diet and preventive veterinary care, including regular vaccinations and parasite control, prevent anemia in most dogs. Keep your dog inside or in a fenced yard. Roaming dogs are more likely to encounter cars, toxins, and contagious diseases.
When treating anemia, your veterinarian will address the cause and provide medical support until your dog's erythrocyte numbers rise. Supportive care may include oxygen therapy to maximize tissue oxygenation, intravenous fluids to maintain adequate blood volume and pressure, and blood transfusions. Your veterinarian also will treat any concurrent illnesses, such as diabetes, kidney disease, liver disease, and cancer.
Maintaining a balanced diet provides the iron and vitamins your dog needs to produce red blood cells. Some dogs also require iron and vitamin supplements. (Be aware that oral iron supplements may cause unexplained death in kittens and should be avoided.)
Sometimes dogs ingest metals and develop zinc toxicity. For example, pennies minted after 1982 and zinc bolts from dog carriers can induce anemia. If this is the case, your veterinarian will use a flexible endoscope to retrieve the item. If unsuccessful, he or she likely will recommend surgery.
Depending on the diagnosis, your veterinarian may prescribe one of the following medications:
- Anthelmintic medications treat intestinal parasites.
- Flea products control blood-sucking fleas or lice.
- Antibiotics treat infections.
- Immunosuppressive agents suppress an overactive immune system.
- Chemotherapeutic agents treat cancer but require close monitoring because they also can suppress the bone marrow.
- Vitamin K prevents or halts bleeding if your dog ingests rat poison.
Prognosis
The prognosis for anemic dogs varies. Some causes, such as flea infestation, are easily treated if the condition hasn't progressed too far. Other causes of anemia are much more serious—your veterinarian can advise you of the most likely outcome.
