64 WOUNDS AND BRUISES. 



is, the longer will it keep fresh. The presence of bacteria in a wound is 

 objectionable ; because they not only injuriously afieot the wound, but may 

 also cause serious if not fatal damage to the_ animal's general health. 



ANTISEPTIC TREATJIENT OF WOUNDS.— In order to check the 

 injurious action of bacteria, we apply to wounds c'ertain agents called anti- 

 septics, some of which, like iodoform, nullify the action of bacteria; and 

 others, like carbolic acid, destroy them. In a surgical operation which 

 necessitates the use of the knife, we employ an antiseptic to disinfect the 

 parts about the wound, as well as the wound itself, unless we are certain 

 that the wound is absolutely free from putrefactive germs, which are 

 readily carried to it by the Imife, ordinary water, our hands, etc. In apply- 

 ing an antiseptic, we must be careful that it is not so strong as to injure 

 the divided tissues. 



Asepsis is the employment of means and substances absolutely free from 

 infective agents. For example, water which has been boiled and which has 

 thus become aseptic, can be used for washing wounds. 



All antiseptics have, more or less, an injurious action on the tissues, as 

 well as on microbes, and therefore they diminish the power of resistance 

 possessed by the part. Aseptic surgery, which is based on the employment 

 of aseptic agents that have no injurious action on the tissues, has been in- 

 vented, in order to avoid this drawback. Theoretically it is perfect ; but in 

 veterinary practice, the only true way to obtain asepsis, is to use anti- 

 septics. 



From the foregoing considerations we may draw the following con- 

 clusions : — 



1. That the fact of a wound of moderate size and untainted with dirt, 

 remaining exposed to the atmosphere for even an hour or so, need not pre- 

 clude the hope of getting it to heal without pus being formed. 



2. That even if we cannot exclude bacteria from a wound, the more we 

 hold them in check (by the observance of cleanliness and by the use of 

 suitable antiseptics), the quicker will the wound heal, and the less risk will 

 the animal run, of becoming inoculated by disease germs. 



3. In the treatment of a wound which is free from bacteria (like those 

 inflicted during an operation that has been carried out under strict con- 

 ditions of cleanliness), we should, if possible, apply a dry dressing in 

 preference to a wet one, for water favours suppuration (the formation of 

 pus), which is the great hindrance to repair in a, wound. If, however, 

 bacteria have gained an entrance into a wound (as would be the case in 

 broken knees and ordinary cuts, especially if they have become con- 

 taminated by dirt), we should freely wash the parts with some antiseptic 

 solution (such as one of carbolic acid or creolin, page 67), so as to check 

 the action of any bacteria that may be present. 



ARREST OF BLEEDING.— Arteries are tubes which consist of three 

 (internal, middle and external) coats or tunics. The internal coat closely 

 resembles a serous membrane (the smooth membrane which covers the lungs 

 or liver, for instance). The middle coat is formed of yellow elastic fibres, 

 and of muscular fibres ; the former predominating in the large arteries • the 

 latter in the small ones. Hence, the larger the artery, the greater tenciency 

 it has to remain open when cut across. In the dead subject, we may 

 recognise the presence of large arteries by the fact that their divided ends 

 gape, and that they are empty. The external coat is composed principally 

 of connective tissue, and is, consequently, much the strongest of the three. 

 Veins are of similar structure to arteries, except that their tunics are much 

 thinner and weaker. 



If an artery is cut in two, the consequent irritation causes the muscular 

 fibres of the middle coat to contract and thus to draw the ends of the artery 

 into its sheath, and also to diminish the calibre of the tube, especially at its 



