Common Laboratory Techniques

Common laboratory techniques used in animal studies include blood withdrawal, serum and plasma separation, anesthetics, and euthanasia.

Blood withdrawal 

Blood withdrawal is the process of collecting blood samples from animals for various analyses and research purposes. 

It is typically performed using aseptic techniques and specialized equipment such as syringes and needles. 

The collected blood can be used for hematological, biochemical, or immunological investigations, providing valuable insights into the animal's health and physiological parameters.

There are several methods for collecting blood from experimental animals, depending on the specific requirements of the study and the species of animals involved. Here are some common methods for blood collection.

Venipuncture

This is the most common method for blood collection in animals. It involves accessing a peripheral vein, typically in the tail, ear, wing, or leg, using a syringe and needle. The site is usually prepared by cleaning with an antiseptic solution before inserting the needle into the vein to withdraw the desired amount of blood.

Cardiac Puncture

Cardiac puncture is a method used when larger blood volumes are required or when specific blood components need to be collected. It involves accessing the heart through the thoracic cavity. This method should only be performed under anesthesia and by trained personnel due to its invasive nature.

Retro-orbital Sinus Sampling

This method is commonly used in small laboratory rodents, such as mice and rats. It involves collecting blood from the retro-orbital sinus, which is a blood-filled space behind the eye. A capillary tube or a glass microcapillary is inserted into the sinus to collect a small volume of blood.

Tail Vein/Nick Method

This method is often used in mice and rats for small-volume blood collection. A small incision or a needle prick is made on the tail vein, and blood is collected using a capillary tube or microtainer. It is important to minimize stress and discomfort to the animals during this procedure.

Saphenous Vein Sampling

This method is commonly used in small laboratory animals such as mice and rats. The saphenous vein, located on the hind limb, is accessed by gently restraining the animal and carefully inserting a needle into the vein to collect the blood sample.

Table: Various techniques for blood withdrawal in laboratory animals

Laboratory Animal Techniques of Blood Withdrawal
Mouse Tail vein nick, Retro-orbital sinus sampling, Saphenous vein sampling
Rat Tail vein nick, Retro-orbital sinus sampling, Saphenous vein sampling
Rabbit Ear vein puncture, Marginal ear vein
Guinea Pig Jugular vein puncture, Saphenous vein sampling
Hamster Retro-orbital sinus sampling, Saphenous vein sampling
Ferret Jugular vein puncture, Saphenous vein sampling
Non-Human Primate Femoral vein puncture, Saphenous vein sampling

The choice of technique may vary depending on the specific requirements of the study, the size of the animal, and the accessibility of the veins. It is important to follow proper ethical guidelines and receive appropriate training to ensure the well-being of the animals during blood withdrawal procedures.

Serum and Plasma Separation

Once blood is withdrawn, it can be processed to obtain serum or plasma. 

Serum is the liquid component of blood obtained after coagulation, while plasma is the liquid component obtained by anticoagulating the blood sample. 

Both serum and plasma contain valuable proteins, enzymes, hormones, and other molecules that can be analyzed for diagnostic or research purposes. Separation techniques like centrifugation are commonly used to obtain clear serum or plasma samples for further analysis. 

Anesthetics

Anesthetics are substances used to induce temporary loss of sensation or consciousness in animals, ensuring their comfort and reducing pain during various procedures. Anesthesia allows for surgical interventions, invasive procedures, and imaging studies without causing undue stress or pain to the animals.

Different anesthetic agents are used depending on the species, size, and purpose of the study.

*(prolonged anaesthesia: terminal procedures only)

Atropine: Dose 0.02-0.05 mg/Kg for all species by SC or IM or IV routes to reduce salivary and bronchial secretions and protect heart from vagal inhibition, given as pre-anesthetic medication.

IM = intramuscular: IV = intravenous; IP = intraperitoneal; SC = subcutaneous

Euthanasia

Euthanasia is the humane and painless method of inducing a quick and irreversible death in animals. It is employed to minimize suffering when animals are no longer needed for research or are experiencing severe pain or distress. 

Euthanasia methods must comply with ethical guidelines and regulations and should be performed by trained personnel using approved techniques. 




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