Part 2

When we undertake the consideration of those features of iodine therapy which have to do with its adaptability to definite remedial ends, we enter upon a field of thought that may take several forms.

We are concerned, in this treatise, only with matter relating to regional, topical, or local applications of the agent under discussion, and we can well begin the consideration with the identification of the agent itself and the different forms under which it is most commonly used. For all practical purposes, we can confine the discussion of the agent itself to that of the four forms, or preparations, of iodine in almost universal use by practitioners of veterinary medicine and surgery. When, in veterinary medicine, allusion is made to iodine, it is almost, without exception, to one of the following preparations:

1. Tincture of Iodine. 2. Ointment of Iodine. 3. Aqueous solutions of Iodine. 4. Oily solutions or mixtures of Iodine.

Only in rare cases, and then under specific reference, is iodine used in other forms, or in its elemental state, in veterinary medicine. Iodine is a very active agent, chemically as well as therapeutically, and is not readily compatible with other agents. It is for this reason, that combinations of iodine with other drugs and chemicals are not common, and therein lies a distinction for iodine that not many other therapeutic agents can claim; namely, that beneficial effects resulting from iodine medication are almost, without question, due to it alone; it is hardly ever applied in combination with synergists which might obscure the activity of individual ingredients.

This remarkable therapeutic activity of iodine is such that, when properly applied in some of its forms, its presence can be demonstrated in the underlying tissues. After prolonged courses of topical application, its action is occasionally appreciated, both subjectively and objectively, in the evidence of more or less clearly defined constitutional or systemic indications of its presence within the animal organism.

From this, it is apparent that, in iodine preparations of a particular class, we have an agent whose topical remedial effects are, in some slight measure, due to systemic action; in part at least, this action being the effect of great physiological activity exerted in the limited area of its topical application. In some degree this activity of certain preparations of iodine can be explained by reference to the chemical properties inherent in iodine as elemental matter, and in its well-known affinity for certain elemental constituents of the tissues of the animal organism.

The foregoing throws some light on the therapeutic accomplishments of iodine preparations, when topically applied, and, to a certain extent, explains its modus operandi in a physiological sense--an understanding somewhat essential from an ethical standpoint. The old theory, which would ascribe to an increase in function of the regional lymphatic glands all the agreeable therapeutic effects of local iodine applications, does not cover enough ground; it is only when we amplify this theory, with the assumption of the considerations aired in the foregoing paragraphs, that we find it possible to attain a clear understanding of the physiological action of iodine preparations applied regionally.

The Clinical Aims for topical therapy are to be classified as follows:

1. PROPHYLACTIC. 2. AMELIORATIVE. 3. CURATIVE.

Under these three heads, we further sub-classify the actual clinical conditions, which are indicated, into the following:

Under 1. Surgical preparatory technique.

Under 2. Acute pathological conditions, in the corrections of which topical applications of iodine preparations are used as an adjunct to internal medication with other agents.

Under 3. Chronic pathological conditions, in which one or more of various iodine preparations, locally applied, constitutes the entire treatment.

This classification and sub-classification is important and essential when we endeavor to make our use of iodine conform to ethical standards; it is also very essential to the attainment of certain therapeutic ends in actual practice.

1. THE LOCAL APPLICATION OF PREPARATIONS OF IODINE IN THE SENSE OF PROPHYLACTIC AIM IN SURGERY.

The exhaustive pre-operative washing and scrubbing of the integument, that veterinary practitioners applied to their surgical patients in years past, has given way almost entirely to iodine painting. Even those surgeons who still adhere to the scrubbing and washing of the parts about to be incised, complete the process with an application of iodine thereafter.

An application of iodine to the skin covering the region that is about to be invaded by the knife of the surgeon, has been found much more efficacious and much more reliable than has the washing and the scrubbing with antiseptic solutions, soaps and other agents. Not only this, but it has also greatly simplified and shortened an otherwise tedious, prolonged and sloppy technique. Whereas, the surgeon formerly spent from fifteen minutes to half an hour scrubbing and washing the field of operation, he now applies a few coats of iodine tincture--a few strokes of the swab or brush--and it is done.

This simplified technique has the added advantage of the total elimination of basins, brushes, and sponges for use in the preliminary stages of an operation, as well as the agreeable absence of the wet, sloppy field that inevitably resulted from the use of the older method in veterinary practice. Besides, it spares the patient in more ways than one, especially in the cold months of the year when, in a veterinary practice, operations frequently have to be performed in cold stables, or even in the open.

While the application of tincture of iodine gives ample protection from skin infection in surgical operations, there are a few things to be observed that have to do with making the application correctly. First, in veterinary patients, the hair must be clipped off and the area shaved clean. The area clipped and shaved should be slightly greater in extent than the field actually to be invaded by the knife. When the clipping and shaving have been done, the area should be lightly brushed with a stiff, dry brush, in order to remove dandruff and scurf.

The second--and the most important--point is that the surface that is to be painted with the tincture of iodine be perfectly dry. In the event that the area to be painted should contain a deposit of filth, oily or greasy in nature, this should first be removed by swabbing and wiping with gauze or cotton saturated with gasoline, benzine or ether; these remove oily, greasy or fatty filth and evaporate quickly, leaving the area perfectly dry and clean. Washing with watery solutions, previous to the iodine application, is not recommended under any conditions.

When the area has been clipped, shaved, freed from grease or other filth, and then allowed to become perfectly dry, the tincture of iodine is applied liberally with a soft brush, or with a cotton swab. This is allowed to dry for a minute or two; another application is then made directly on top of the first one, allowed to evaporate to dryness, and the field is ready for the incision.

As iodine readily attacks metals, and spoils the plating on instruments, no instrument should be allowed to come in contact with the painted area while it is still moist; neither should the iodine be used for disinfecting purposes on any utensils or apparatus made of metal. The fact that the iodine may injure instruments can not be considered in the light of a disadvantage, if the above precautions are taken.

Another practice that has come to be recognized quite generally among surgeons is that of painting the edges of the surgical wound with pure tincture of iodine just before the wound is to be closed with sutures. Whether this is good practice, on general principles, is a matter that is open to debate. If the painting is done carefully, so that a pool of iodine tincture is not formed by the surplus gathering by gravitation into the deeper recesses of the wound, this may be considered good practice. On the whole, however, it would appear that the iodine could act, in many instances, as an undesirable irritant when it comes in contact with delicate, freshly incised tissues.

As the object, in modern surgery, is to eliminate all things, even the slightest, that may hinder prompt repair and smooth healing of the invaded tissues, the presence of such an active agent as pure tincture of iodine in a surgical wound may be looked upon as interfering with the carrying out of that object.

On the other hand, in surgical wounds of an already infected character in which primary union would be out of the question, the application of pure tincture of iodine, in liberal amounts, can not be too highly endorsed.

The latter statement applies, with even greater force, to all wounds of an accidental character in the fleshy portions of the anatomy.

It is also the practice of many veterinary surgeons to apply pure tincture of iodine to the wound after the sutures have been put into place. This is a very satisfactory practice, if the painting is done gently and not too freely. An excess of the tincture of iodine--if the wound edges have not been coapted perfectly--may result in cause for stitch abscess when a considerable amount of the iodine becomes pocketed in some part of the wound under the line of suture.

In certain animals, whose skins are very tender, the local application of pure tincture of iodine, previous to surgical incision, is followed, in a few days, by slight peeling of the integument. This is so rare an occurrence, however, and of so little consequence, that it need not be considered, and can not be looked upon as a drawback to this otherwise salutary practice.