Phlebotomy: Blood Collection From Different Animals is a fundamental technique in veterinary clinical pathology, essential for diagnosing and monitoring the health of various animal species. Blood collection is essential for analyzing hematological and biochemical parameters to diagnose diseases, monitor health, and assess organ function in animals. The importance of Phlebotomy: Blood Collection From Different Animals lies in its ability to provide critical diagnostic data, enabling early detection of diseases, assessment of treatment efficacy, and support for research. Proper execution ensures animal welfare and accurate results, making it a vital skill for veterinary students. Additionally, Phlebotomy: Blood Collection From Different Animals supports species-specific health management, from small lab animals like mice to large domestic animals like horses, highlighting its broad application in veterinary science.
Phlebotomy is derived from two Greek words: “Phlebo” meaning “related to blood” and “Tomy” meaning “to make an incision.” Therefore, phlebotomy refers to the practice of making an incision in a vein, usually to collect blood for diagnostic or medical purposes.
Venipuncture comes from the Latin word “Vena,” meaning “vein,” and “puncture,” meaning “to pierce.” The term specifically refers to the act of puncturing a vein, commonly performed to draw blood.
A venipuncturist—which may be a doctor, nurse, or laboratory technician—is the individual trained to perform venipuncture. They draw blood from patients for various reasons, such as diagnostic testing, medical research, or transfusions.
Need for Blood Collection
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Health Assessment: Evaluates parameters like red blood cell count, glucose levels, liver, and kidney function.
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Disease Diagnosis: Detects infections, anemia, metabolic disorders, and immune system abnormalities.
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Therapeutic Monitoring: Assesses drug levels and treatment efficacy, ensuring safe and effective therapy.
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Regulatory and Research Purposes: Supports studies in toxicology, pharmacology, and disease modeling.
Things Needed for Blood Collection
Venipuncture equipment used in blood collection from animals, including gloves, needles, evacuated collection tubes, the hub, syringes, a tourniquet, and bandages/tape. It also highlights needle gauge sizes and their selection based on injection types (intradermal, intramuscular, subcutaneous). This equipment is crucial for ensuring safe, sterile, and effective blood collection, minimizing animal stress, and preventing contamination or hemolysis. Proper selection of needle gauge and tools tailored to species and vein size enhances sample quality and supports accurate clinical pathology diagnostics.
Injections in animals serve different purposes, and each type requires selecting an appropriate site and needle. Intravenous (IV) injections are used for blood collection and for delivering drugs that require rapid action. Intramuscular (IM) injections are slower than IV but faster than subcutaneous (Subcut) ones, which are ideal for medications needing slow absorption. Intradermal injections are typically used for vaccines and insulin administration.
The choice of injection site and needle type depends on both the injection method and the animal’s species and size. For IV injections or blood sampling, selecting the correct needle gauge is especially important. Needle size and gauge are inversely related—larger gauge numbers correspond to thinner needles. Because animals vary in age, species, and body size, the needle gauge must be chosen carefully to ensure safe and effective blood collection.
Blood Collection Techniques by Species
Blood collection requires careful selection of site, needle gauge, and volume to ensure animal safety and sample quality. Below are species-specific guidelines:
Mouse
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Sites: Tail Vein (most common), Retro-Orbital Sinus (requires anesthesia, ethical concerns), Saphenous Vein.
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Needle Gauge: 25-27 gauge.
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Volume: 0.1-0.5 mL.
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Notes: Use minimal restraint; retro-orbital bleeding is less preferred due to potential tissue damage.
Rabbit
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Sites: Marginal Ear Vein (common), Jugular Vein, Central Ear Artery (for larger volumes).
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Needle Gauge: 22-25 gauge (Ear Vein), 18-22 gauge (Jugular).
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Volume: 1-5 mL, up to 10 mL if needed.
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Notes: Warm ear to enhance vein visibility; avoid excessive pressure to prevent hematoma.
Chicken
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Sites: Wing Vein (brachial, common), Jugular Vein.
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Needle Gauge: 22-25 gauge.
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Volume: 1-3 mL, up to 5 mL if necessary.
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Notes: Handle gently to avoid stress; wing vein is preferred for ease of access.
Fish
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Sites: Caudal/Tail Vein (most common).
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Needle Gauge: 25-27 gauge.
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Volume: 0.1-1 mL, depending on species and size.
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Notes: Requires sedation in some cases; ensure minimal handling to reduce stress.
Dogs and Cats
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Sites: Cephalic Vein (forelimb), Jugular Vein (neck), Lateral Saphenous Vein (hindlimb).
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Needle Gauge: 22-25 gauge (Cephalic/Saphenous), 18-22 gauge (Jugular).
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Volume: 1-5 mL, up to 10 mL if needed.
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Notes: Use gentle restraint; jugular vein preferred for larger volumes.
Horses
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Sites: Jugular Vein (neck, primary site).
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Needle Gauge: 16-18 gauge.
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Volume: 10-20 mL, larger volumes if needed.
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Notes: Ensure proper restraint; use vacutainer for efficient collection.
Cattle
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Sites: Jugular Vein (neck), Coccygeal Vein (tail).
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Needle Gauge: 16-18 gauge (Jugular), 18-20 gauge (Coccygeal).
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Volume: 10-20 mL, larger volumes if needed.
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Notes: Coccygeal vein is easier for quick sampling; jugular for larger volumes.
Sheep and Goats
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Sites: Jugular Vein (neck), Cephalic Vein (forelimb).
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Needle Gauge: 18-22 gauge (Jugular), 20-22 gauge (Cephalic).
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Volume: 5-10 mL, larger volumes if necessary.
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Notes: Clip wool/hair for better vein visualization; use minimal restraint.
Camel
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Sites: Jugular Vein (primary site).
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Needle Gauge: 16-18 gauge.
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Volume: 20-30 mL, larger volumes if necessary.
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Notes: Requires experienced handling due to size and temperament.
General Guidelines
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Blood Volume Limits: Total circulating blood volume is 50-80 mL/kg body weight. Non-terminal collection should not exceed 1% of body weight (10 mL/kg) over 14 days to prevent anemia or shock.
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Equipment: Use sterile needles, syringes, or vacutainer systems. Anticoagulants (e.g., EDTA, heparin) depend on test requirements.
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Technique: Ensure aseptic conditions, proper restraint, and minimal stress to avoid hemolysis or inaccurate results.
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Ethical Considerations: Follow institutional guidelines and ethical standards to minimize animal discomfort and ensure welfare.
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Sample Handling: Store and transport samples appropriately (e.g., refrigerated for most biochemical tests) to maintain integrity.
Safety and Precautions
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Training: Only trained personnel should perform blood collection to avoid injury to the animal or handler.
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Site Preparation: Clean the site with alcohol to prevent infection.
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Post-Collection: Apply pressure to stop bleeding; monitor for hematomas or distress.
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Species-Specific Risks: Be aware of stress-induced physiological changes (e.g., elevated cortisol in chickens) or anatomical challenges (e.g., small veins in mice).
