Methods Employed and Experiments

METHODS EMPLOYED AND EXPERIMENTS The Existing Law in Britain.—Thepresent law relating to experiments on animals was passed in 1876. At that time bac teriology was in its infancy, biochemistry was unborn and the majority of these experiments were physiological. The Act, there fore, was drafted with a view to physiology. At the present time the vast majority of animal experiments are inoculations in re searches upon bacterial diseases or cancer. Every experiment must be made in a registered place open to government inspec tion. But inoculation experiments are sometimes permitted in non-registered places, for the immediate study of outbreaks of disease, or if circumstances render it impracticable to use a registered place. Every experiment must be made under a licence.

Most experiments are made not under a licence alone, but under a licence plus one or more certificates, and the wording and working of these certificates must be clearly understood, because it is over them that the question arises as to the amount of pain inflicted by these experiments. Under the licence alone, the animal must be kept under an anaesthetic during the whole of the experiment ; and "if the pain is likely to continue after the effect of the anaesthetic has ceased, or if any serious injury has been inflicted on the animal," it must be killed forthwith under the anaesthetic. Thus, under the licence alone, it is impossible to make an inoculation; for the experiment consists, not in the intro duction of the needle under the skin, but in the observation of the results of the inoculation. A guinea-pig inoculated with tu bercle cannot be kept under an anaesthetic till the disease ap pears. The disease is the experiment, an experiment made without an anaesthetic, and not authorized by the licence alone.

To remove these disabilities, the Act empowers the Secretary of State for Home Affairs to allow certificates to be held with the licence. They must be recommended by two signatures, and the home secretary attaches to licences and certificates such endorse ments and ,restrictions as he thinks fit. The Act is administered with great strictness, under a careful system of enquiry and reference.

The certificates are distinguished as A, B, C, E, EE and F. Certificate D, which permitted the testing, by experiments, of "former discoveries alleged to have been made," has fallen into disuse. Certificate C permits experiments to be made in illus tration of lectures. They must be made under the provisions contained in the Act as to the use of anaesthetics. Certificates E and EE permit experiments on dogs or cats; Certificate F per mits experiments on horses, asses or mules. These certificates are linked with Certificate A (which allows experiments to be made without anaesthesia) or Certificate B (which permits the keeping alive of the animal after the initial operation).

Thus, in Great Britain experiments on animals may only be performed (I) by a duly licensed person; (2) in an approved and registered place of research; (3) for an approved specific purpose; (4) on specific kinds of vertebrate animals (the Act not applying to invertebrates) ; (5) within a specified period or on a specified number of animals; (6) the word "experiment" is not allowed to cover more than one animal.

The United States.

Inthe United States attempts have re peatedly been made since about 1890 to obtain special legislation limiting experiments on animals. Responsible heads of depart ments in medical schools and research institutes have consistently opposed these attempts. They have argued that there has been no demonstrated abuse of animals for experimental purposes in the laboratories of the United States, that if abuse should appear the existing laws against cruelty would suffice to correct it, and that until the general law is proved inadequate special legislation is unnecessary. Up to 1929 no special legislation had been passed restrictive of animal experimentation for purposes of scientific discovery. About 1910 a system of rules governing the treatment of animals used for research was drawn up by a committee of the American Medical Association. These rules have been adopted by corporate vote in practically all institutions engaged in medical research. They constitute a mode of self-regulation of investi gators engaged in animal experimentation. In each instance the director of the laboratory is made responsible for the character of the experiments performed in his laboratory.

Classes of Experiment.

Fromthis brief account of the chief provisions of the Act we come to consider the general method of experiments on animals. The animals most used for inoculations without anaesthetics are mice, rats, guinea-pigs and rabbits. The act of inoculation is not in itself painful. A small area of the skin is carefully shaved and cleansed ; that it may be aseptic, the hypodermic needle is sterilized and the method of hypoder mic injection or of vaccination is the same as it is in medical practice. In a few instances cultures of micro-organisms have been made in the anterior chamber of the eye, by the introduction of a needle behind the cornea. This might be thought painful, but cocaine renders the surface of the eye wholly insensitive. Many operations of ophthalmic surgery are done under cocaine alone, and the anterior chamber of the eye is so far insensitive that a man may have blood or pus (hypopyon) in it, and hardly be conscious of the fact. The results of inoculation are in some cases negative, in others positive; the positive results are, in the great majority of cases, not a local change, but a general infection which may end in recovery, or in death.

The diseases thus induced may, in many cases, fairly be called painless—such are septicaemia in a mouse, snake-venom in a rat, the growth of cancer grafts beneath the skin of inoculated rats or mice, and malaria in a sparrow. Rabbits affected with rabies do not suffer in the same way as dogs and some other animals, but become subject to a painless kind of paralysis. It is probable that animals kept for inoculation have, on the whole, less pain than falls to the lot of a like number of animals in a state of nature or in subjection to work: they are well fed and sheltered, and escape the rapacity of larger animals, the inevitable cruelties of sport, and the drudgery and sexual mutilation that man inflicts on the higher domestic animals.

We now come to experiments made under Certificate B (which must be linked with Certificate EE for any experiment on a dog or a cat). Three instances may be given: an operation on the brain, removal of part or the whole of a secreting gland, and the establishment of a fistula. It is to be noted that, for these and similar operations, profound anaesthesia and the strict ob servance of asepsis are necessary for the success of the experi ment : the operation could not be performed without anaesthesia ; and the experiment would fail if the wound suppurated. These operations are such as are daily performed in surgery.

As to operations on the brain we know from human cases that the surface of the brain is not sensitive. Therefore the re moval or destruction of a portion of the surface of the brain, or the division of some tract of central nervous tissue, though it may entail some loss of power or of control, does not cause pain. Tension within the cranial cavity, as in cases of cerebral tumour or cerebral abscess, may indeed cause great pain; and, if the aseptic method fails in an experiment, inflammation and tension ensue: in that case the animal must be killed.

The removal of part or the whole of a secreting gland (e.g., the thyroid, the spleen, the kidney) is performed by the same methods, and with the same precautions, as in human surgery. Profound anaesthesia, and strict asepsis are fundamental. The skin over the part to be removed must be shaved and carefully cleansed for the operation; the instruments, sponges and liga tures must be sterile, not capable of infecting the wound ; and when the operation is over, the wound must be carefully closed with sutures, and left to heal under a proper surgical dressing.

The establishment of a fistula, again, is an operation practised in large numbers of surgical cases. The stomach, the gall-bladder and the large intestine are opened for the relief of obstruction, and kept open, either for a time or permanently, according to the nature of the case. Under anaesthesia, the organ that is to be opened is exposed through an incision made through the struc tures overlying it and is secured in the wound by means of fine sutures. When it has become adherent there, it is opened by an incision ; no anaesthetic is needed for this purpose, because these internal organs are so unlike the skin in sensitiveness that an in cision is hardly felt : the patient may say that he "felt a prick," or he may be wholly unconscious that anything has been done. A fistula thus established is not afterwards painful, though there may be some discomfort now and again.