Bone marrow aspiration is a safe and beneficial procedure performed to help with the evaluation and diagnosis of various conditions affecting the bone marrow in dogs. The procedure is most often indicated when abnormalities are identified in peripheral blood.<\/p>\n
General anesthesia is recommended for those patients that can tolerate it. The most commonly sampled sites are the proximal humerus and the ilium. Samples to submit to a clinical pathologist include a stained slide, unstained slides, and a peripheral blood smear. If the aspirate is nondiagnostic, a bone marrow core biopsy may be needed.<\/p>\n
Take-Home Points<\/strong><\/p>\n Bone marrow is located within the center of bones. It is the main hematopoietic organ at birth that produces blood cells (erythrocytes, leukocytes) and platelets. Active marrow is located throughout most flat and long bones of the body in young animals and will recede from long bones with maturity.1,2<\/sup> In adults, active marrow persists in the flat bones of the vertebrae, sternum, ribs, and pelvis, along with the proximal ends of the humerus and femur.1,2<\/sup><\/span><\/p>\n Bone marrow aspiration and evaluation are performed in conjunction with clinical findings and diagnostics, including a complete blood count, morphologic changes on peripheral blood smears, other laboratory data, and imaging.3<\/sup> Bone marrow cytopathology and histopathology are vital tools for understanding diseases and conditions that affect or arise from the bone marrow. Evaluating aspirate and core bone marrow samples provides information about the status of the bone marrow and its ability to correct abnormalities in the peripheral blood and can indicate infection, myelofibrosis, necrosis, or neoplasia.4,5<\/sup><\/span><\/p>\n Bone marrow aspiration is safe and beneficial. It is most commonly performed when abnormalities are detected in peripheral blood, including persistent neutropenia, unexplained thrombocytopenia, nonregenerative or poorly regenerative anemia, or a combination thereof.5<\/sup> Any patient with bicytopenia or pancytopenia without adequate regeneration or with blood cells showing abnormal morphology should undergo bone marrow evaluation to determine the source of the disease.6<\/sup> Bone marrow can also be examined to stage neoplastic diseases (e.g., lymphoma, mast cell tumors), estimate levels of body iron stores, evaluate lytic bone lesions, and search for suspected occult neoplasia or infection.5,6<\/sup> It can also indicate an underlying cause for hyperproteinemia secondary to multiple myeloma<\/a>, leishmaniasis<\/a>, and systemic fungal diseases<\/a>.5<\/sup> Bone marrow evaluation is less helpful if the anemia is regenerative or if the underlying cause of the neutropenia is sepsis<\/a>.1<\/sup><\/span><\/p>\n Bone marrow aspiration is contraindicated for patients who have metabolic bone disease or are not stable enough to undergo sedation or general anesthesia.7<\/sup> Sedation combined with systemic or local analgesia<\/a> or general anesthesia is required because the procedure is associated with moderate pain, the most commonly reported complication.6,8,9<\/sup> General anesthesia is recommended for smaller dogs and cats. Complications are rare but can include pain, bleeding, bruising, and fracture if the bone is weak or compromised.7<\/sup> Patients with coagulopathies and severe thrombocytopenia can experience prolonged hemorrhage at the biopsy site, which can be controlled by applying direct pressure to the sampling site for several minutes.3<\/sup> A study of 160\u00a0bone marrow procedures performed in dogs and cats reported adverse events in 14% (22\/160) and an overall complication rate of <1%, excluding pain.8<\/sup><\/span><\/p>\n In dogs, bone marrow aspirates are often collected from the proximal humerus or ilium. A special 14- to 18-gauge needle with stylet is placed into the bone marrow cavity, and cells are subsequently aspirated.6<\/sup> These needles are designed to penetrate cortical bone without becoming obstructed.6<\/sup> Other sites in dogs include the sternum, ribs, and proximal femur. Aspiration from the pelvis and femur is challenging if the region contains abundant adipose tissue.6<\/sup> <\/span><\/p>\n Historically, the sternum has not been aspirated in animals due to concerns for penetration into the thoracic cavity, especially in smaller dogs.4,6<\/sup> However, a study involving 26 systemically healthy beagles showed that collecting sternal bone marrow aspirates by using 20- or 22-gauge hypodermic needles was safe and equivalent in quality to samples from the humerus and ilium.6<\/sup> The sternum is a viable site for aspiration due to its softer bone and minimal soft tissue coverage compared with the ilium, femur, or humeral head, and hematopoiesis remains active through adulthood.4,6,9<\/sup> <\/span>TABLE 1<\/b><\/span> summarizes the common bone marrow collection sites and any special considerations pertinent to each site.<\/span><\/p>\n The needed materials and equipment should be gathered (<\/span>BOX 1<\/b><\/span>) and prepared (<\/span>BOX 2<\/b><\/span>).<\/span><\/p>\n\n
Indications for Bone Marrow Aspiration<\/h2>\n
Contraindications for Bone Marrow Aspiration<\/h2>\n
Collection Sites for Bone Marrow Aspiration<\/h2>\n
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<\/a><\/p>\nProximal Humerus Procedure<\/h2>\n
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