📝 STANDARD DESCRIPTION:
Bone Marrow Aspiration Sites:
• Cattle / Horse: Sternum (manubrium), wing of ilium (tuber coxae or sacrale).
• Dog / Cat: Iliac crest, proximal humerus (greater tubercle), proximal femur (trochanteric fossa).
• Bird: Proximal tibiotarsus.
Cerebrospinal Fluid (CSF) Collection Sites:
• Atlanto-occipital (Cisterna Magna): Standard in large animals; needle inserted on dorsal midline at AO joint into the cisterna magna.
• Lumbosacral (L6-S1) space: Standard in dogs; safer (no risk of medulla injury).
Standard procedure: aseptic preparation, local anaesthetic, animal restrained in lateral or sternal recumbency, slow needle advance until CSF drips out.
📚 DETAILED DESCRIPTION:
BONE MARROW & CSF COLLECTION
BONE MARROW ASPIRATION:
• Indications: Diagnosis of anaemia, leukemia, lymphoma, multiple myeloma, immune-mediated thrombocytopenia (when peripheral blood doesn't explain the disease).
• Sites:
– Sternum (Manubrium): Most accessible in cattle & horse. Animal cast or lightly sedated; needle in midline, 4-5 cm depth (avoid penetrating into the thoracic cavity!).
– Wing of Ilium (Tuber coxae or sacrale): Aspiration through the iliac crest. Common in cattle.
– Proximal Humerus (greater tubercle): Standard in dog/cat — needle into trabecular bone of greater tubercle.
– Iliac crest: Easy in dog standing.
– Trochanteric fossa of Femur: Dog under anaesthesia.
– Bird: Proximal tibiotarsus (avian bones often pneumatized — choose carefully).
• Equipment: Jamshidi needle (15-18G with stylet), 10-mL syringe with EDTA.
• Aspirate = 0.5-1 mL of marrow + a core biopsy if needed.
CEREBROSPINAL FLUID (CSF) TAP:
• Indications: Suspected meningitis (bacterial/viral), encephalomyelitis, neurological disease (rabies, BSE), increased ICP.
• Sites:
– Atlanto-occipital site (Cisterna Magna):
Animal: General anaesthesia or heavy sedation, lateral recumbency, head flexed.
Landmarks: Dorsal midline; intersection of line connecting the cranial borders of the wings of the atlas with the midline.
Needle: 18-20 G spinal needle. Advance slowly until 'pop' of dura → CSF drips.
Volume: Collect 1-2 mL by gravity (avoid suction).
– Lumbosacral space (L6-S1):
Standard in dogs (cat & smaller animals): At highest points of iliac crests, midline, palpate L6-S1 space with the dog's pelvis fixed.
Safer than AO tap (no risk of brainstem injury).
Same needle technique.
• CSF Analysis: Total cell count + differential + protein + Gram stain + culture + cytology.
NORMAL CSF VALUES (Approximate):
• Clear & colourless
• <5 cells / μL
• Protein < 0.4 g/L (cisternal) / < 0.45 g/L (lumbar)
• Glucose ~70% of plasma
// COMPARATIVE ANALYSIS
| OX |
AO tap or LS tap; sternal bone marrow standard. |
| HORSE |
AO tap usually under standing sedation in adult; sternal BM aspirate. |
| DOG |
LS tap is preferred (easier, safer). Iliac crest BM aspiration in awake patient. |
CLINICAL RELEVANCE
Iatrogenic blood contamination — common cause of false 'high cells' in CSF. Cervical CSF tap (AO) — cardinal danger = inadvertent brainstem puncture if needle is too deep. Pancytopenia diagnosis requires bone-marrow aspirate — peripheral blood alone is insufficient.
