Anesthesia and execution of experimental animals

Summary

Injectable drug delivery methods in experimental animals include (1) subcutaneous injection (2) intramuscular injection (3) intravenous injection (4) arterial injection (5) intraperitoneal injection and so on. Injectable drug delivery method in experimental animals refers to the injection of sterile drug solution or biological agents into tissues, blood vessels or body cavities by syringes to achieve the purposes of prevention, treatment, assistance in examination, maintenance of normal physiological functions, as well as alleviation of pain and discomfort.

Operation method

Routes of anesthesia and methods of execution of experimental animals

Principle

Anesthesia for experimental animals: commonly used general anesthetics can be divided into volatile anesthetics, such as ether, halothane, methoxyflurane, etc.; non-volatile anesthetics, such as barbiturates, ketamine, chloral hydrate, valium and some new composite anesthetics such as tachypnoea, tachypnoea and so on. From the anesthesia route can be divided into inhalation anesthetics, mainly for the volatile anesthetics mentioned above; intravenous anesthetics, such as sodium pentobarbital, ketamine, etc.; intramuscular injection of anesthetics, such as speed sleep new, speed of anesthesia, valium and so on. From the mechanism of action, they can be divided into central inhibitory anesthetics, such as ether; sedative-hypnotics, such as barbiturates; analgesic anesthetics, such as ketamine; and compounded animal braking agents, such as Sulforaphane, Sulforaphane. Mice, rats, guinea pigs and other animals are small in size, easy to stabilize, easy to inject intraperitoneally, and the effect is faster. Rabbits have obvious veins at the ear margin and are docile, so they can be anesthetized intravenously without holding. For dogs and cats which are easy to hurt and pigs which are large and not easy to keep in position, they can be injected with intramuscular injection of tachypnoea, tachypnoea ana, ketamine or valium first, and when their muscles are relaxed and they do not have the power of resistance, then depending on the degree of anaesthesia and the experimental needs, they can be anaesthetized intravenously, dogs and cats are usually injected through the small saphenous vein of the hind limb, and pigs are generally injected through the vein of the ear margin.

Materials and Instruments

Laboratory animals
Ether Water Procaine injection Phenobarbital sodium Pentobarbital sodium
Degreased cotton Beaker Syringe Procaine injection Scissors Metal probe Syringe Hemostatic forceps

Move

Anesthesia methods for experimental animals:

1, inhalation anesthesia method: the commonly used anesthetic drugs for this method are ether and chloroform. Use wetted ether cotton balls, put into the anesthesia mask, to be anesthetized animal mouth cover, about 5-7 minutes can be. The advantage of volatile anesthetics is that the depth of anesthesia is easy to control, the disadvantage is that the anesthesia will not last too long, and the animal is easy to wake up more quickly.

Intravenous injection method: a common method for dogs and rabbits. When anesthetizing dogs, the mouth should be tied first to prevent biting. The commonly used veins are the small saphenous vein on the outer side of the calf of the hind limb and the cephalic vein on the inner side of the forelimb. When anesthetizing rabbits, the marginal ear vein is used. This anesthesia method is simple, and the animal can be anesthetized continuously for 3-4 hours or more.

3, intraperitoneal anesthesia: this method is commonly used in cats and rodents, in the intraperitoneal injection of anesthetics, to grasp the skin folds at the back of the neck, to control the head movement to prevent bites, quickly pierce the injection needle into the abdominal cavity, the injection is completed and immediately withdraw the needle. When injecting, avoid inserting the needle into the thoracic cavity or bladder, otherwise it will cause the death of the animal or too shallow anesthesia.

Methods of execution of experimental animals:

1, acute blood loss method: this method is applied to small animals such as rats and mice, often by cutting the femoral artery of the animal and bleeding to death. The eyeball removal method can be used to remove the eyeball at the root of the right or left eyeball of the rat, so that it will die of massive blood loss. In the case of dogs, cats or rabbits and other slightly larger animals should first make the animal anesthesia, exposure of the femoral triangle or abdominal cavity, and then cut the femoral artery or abdominal aorta, rapid bloodletting. The animal can die within 3-5min. Using acute blood loss method animals are very quiet, no damage to the animal's organs, but the organ anemia is more obvious, if the collection of tissue specimens to produce pathological sections can be used when this method.

2, guillotine method of this method: for rodents and other small animals, can be used straight scissors knife, can also be used guillotine. The execution time of the animal is short, and the blood content of the organs is less, if you need to collect fresh organ specimens, this method can be used. It can be used to collect fresh organ specimens if fresh organ specimens are required. The guillotine method can cause a sudden interruption of blood circulation and a rapid drop in blood pressure, accompanied by a loss of consciousness, and should only be used in thermophilic animals. It is not recommended to use guillotine method for vertebrates with variable temperature, because they are relatively more resistant to hypoxia.

3、Air embolization method: when air is injected into the vein, its branches can be blocked, and entering the coronary artery of the heart can cause coronary artery blockage, serious blood circulation disorders occur, and the animal will die soon. This method is suitable for the execution of larger animals, rabbits, cats with this method need to be injected into the 20-40mL of air, canine lethal air dose of 80-150mL. due to the application of this method, the animal died of acute circulatory failure, so the organs of the bruising is very obvious.

4、Medullary method This method is applicable to mice, rats and other small animals. For rabbits, it can be used to knock the medulla oblongata to death, using a wooden hammer to hammer the back of the animal's brain, destroying the medulla oblongata, and the animal will die after spasms, which is simple and rapid. For toads, frogs can directly destroy the spinal cord, the metal probe into the occipital foramen magnum, destroying the cerebral spinal cord so that animals die.

5、Chemical drugs to death commonly used euthanasia drugs are: inhalation anesthetics (including carbon dioxide, CO, ether, chloroform, etc.), potassium chloride, barbiturates anesthetics, dichlorodiphenyltrichloroethane (DDT), etc., through the inhalation of drugs or drugs injected into the body.

Caveat

The anesthetist should carefully calculate the dose of anesthetic drug required according to the body weight of the animal and the concentration of the drug. For ease of calculation, sodium pentobarbital is prepared as a 3% solution in sterile saline, which can be converted to 1 ml/kg body weight according to the usual dose of 30 mg/kg body weight. Ketamine hydrochloride is diluted 1:5 to 10 mg/ml and used at a dose of 1 ml/kg body weight. When anesthesia is injected intravenously, the drug should not be pushed in quickly at one time, but pushed in slowly and intermittently, and after injecting 3/4 of the predetermined dosage, it is necessary to slow down the speed of propulsion and observe the corneal reflexes, degree of muscular relaxation, and pain response of the animals while injecting, and stop the injection of the drug immediately when the desired anesthetic state is reached. In order to prevent the anesthetized animals (mainly large animals, such as pigs, dogs, etc.) from asphyxiation due to respiratory obstruction, it is best to perform tracheal intubation after anesthesia and before the experiment to keep the respiratory tract open, and monitor the animal's blood pressure and pulse at any time as much as possible.

Common Problems

1. There are many kinds of animals, with great differences in their physique, as well as different anatomical and physiological characteristics, and different experimental purposes, the medication should be different, and if anesthetics are used in a generalized way, it will cause irreparable losses to the animal's life; even if they are of the same species and live in different areas, the dosage of anesthetics should be differentiated with attention.
   
   

2. Sourced from "Methods of Execution of Laboratory Animals" Journal of Modern Agricultural Science and Technology.
   

For more product details, please visit Aladdin Scientific website.

https://www.aladdinsci.com/