Anesthesia in laboratory animals is a complex system of work. Correct anesthesia treatment is a powerful guarantee for the success of animal experiments. Improper anesthesia treatment will bring difficult analysis errors to the experimental results. In order to obtain a good anesthetic effect, in addition to mastering the basic knowledge and techniques of experimental animal anesthesia, following scientific anesthesia procedures, you should also understand the various factors affecting the anesthesia of experimental animals, such as animal factors, environmental factors.
1. Animal factors
1, 1 age and weight
The response of animals to drugs varies with age. Rats and mice were divided into three groups according to age, juvenile, adult, and old age, and the effects of age on acute toxicity such as ethanol, pentane and dichloroethane were observed. According to LD50 and anesthetic concentration, the sensitivity was shown as juvenile>adult>old age. The age difference in response to poisons may be related to the activity of the enzyme. Young animals are sensitive to phytotoxicity due to the lack of these enzymes. Neonatal rats reached the level of adult rats only about 8 weeks after birth. The rat glucuronyl conversion enzyme reached the level of adult rats at about 30D after birth. In addition, juvenile animals, especially newborn animals, have no complete liver and kidney function and low drug elimination ability. These factors increase the amount of free drugs and tissues into the tissues, and are prone to accumulation poisoning.
Animals with small body weight have a higher basal metabolic rate per unit body weight, so the smaller the animal, the greater the amount of anesthetic dose required per unit body weight. In some chronic experiments, the observation time is longer, and young and young animals can be selected for experimentation.
1, 2 gender
Experiments have shown that animals of different sexes have different sensitivities to the same drug, and the responses to various stimuli are not consistent. The females have different stages in the sexual cycle and the body reactivity during pregnancy and lactation. Therefore, in general, The situation is preferred to select male animals or males and females for experimentation. The basal metabolic rate of male animals is higher than that of females, and the metabolic rate of females during pregnancy is increased, which is sensitive to drugs. For example, alkaloids can be used for male rats aged 5-6 weeks, and analgesic effects can be seen. For example, female rats have no analgesic effect. The amount of ethanol ingested and excreted in 3 months old lWistar rats was calculated according to the unit weight, and the females were more than males.
1, 3 physiological and health status
Thin, muscular animals require a greater amount of anesthetic than fat, because the basal metabolic rate is lower relative to non-metabolic tissues. Activity can increase the metabolic rate, so the amount of anesthesia required for an active animal is large. In animals with poor physical condition, the required anesthetic volume is less tolerated. It is prone to poisoning. Anesthesia time was significantly prolonged after insufficient dog food intake or weight loss of 10% to 20%.
1,4 animal breeding
Ensuring adequate nutrient supply is an important factor in maintaining animal health, with feed being more closely related to animals. Animal growth, development, reproduction, ability to fight disease and all life activities depend on nutrient-rich feed. Animals should be in place a week before anesthesia, giving careful management and keeping them in good health. Feed nutrient-balanced feed, nutrients can not be too high or too low, such as a large number of carnivorous dogs, the basal metabolic rate increased by 90%; mouse feed protein content of less than 20% easy to produce intestinal diseases; guinea pig feed vitamins Lack of scurvy.
2, environmental factors
2, 1 temperature
Within a certain range, the temperature changes slowly, and the body can be automatically adjusted to suit it. However, if the change is too large or too urgent, it will have adverse effects on the body and behavior. Therefore, if the temperature of the experimental environment is too high or too low, the body's resistance will decrease, the sensitivity to anesthetic drugs will increase, and poisoning will occur. This affects the anesthetic effect.
2, 2 humidity
If the humidity is too high, the microorganisms are easy to breed, and too low (less than 40%) tends to cause dust to fly, which is detrimental to the health of the animal. The relative humidity of the air is also closely related to the animal's temperature regulation. In high temperature, the effect is particularly obvious. For example, if the humidity is below 40%, the rat is prone to bad tail disease. Under low humidity conditions, the female mice in lactation of rats or mice are prone to eating. The direct effect of humidity on animal temperature regulation and health status indirectly affects animal responsiveness to anesthetic drugs. Therefore, in the laboratory for animal anesthesia, the relative humidity should be between 40% and 70%, and 50% ± 5% is best.
2, 3 air flow rate and cleanliness
The body surface area per unit body weight of experimental animals is generally larger than that of humans, so the influence of airflow on animals is also large. On the one hand, the air flow rate affects the heat dissipation of the animal's body surface, especially for the animal's body temperature under anesthesia. On the other hand, a suitable air flow rate can discharge the dirty gas in the laboratory, such as ammonia, in time. Experiments have shown that the high concentration of ammonia in the ambient air of the experimental animals can stimulate the mucosa of the animal and cause tearing, coughing, etc. In severe cases, it may cause mucosal inflammation, pulmonary edema or pneumonia. Therefore, the air in the animal laboratory where anesthesia is performed should be kept as fresh as possible, requiring an ammonia concentration of less than 20 mg/L, a gas flow rate of 10 to 25 cm/s, and a gas exchange rate of 8 to 15 times/h. Winter should try to avoid the wind.
In summary, animal factors and environmental factors directly or indirectly affect the animal's health status, so that the body's metabolic enzymes and clearance ability of anesthetic drugs are different, so the sensitivity to anesthetic drugs is different. Therefore, the above factors should be fully considered when anesthetizing animals, and the dose should be increased or decreased as appropriate to obtain a good anesthetic effect.
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