FOOT ROT

Sun (Christchurch), Volume I, Issue 57, 14 April 1914, Page 11

FOOT ROT

ITS CAUSES AND CURE. After nearly a century of discussion, (experimentation, and investigation engaged in by a host of world-renowned scientific and practical men, the conclusion has now been arrived at that there are three forms of footrot, viz: (1) Simple footrot, the ordinary. widespread non-contagious form; (2) contagious foot eczema, or eczema epizootica, the "mal de pied" of the French; and (3) inflammation of the interdigital duct. Such a conclusion is satisfactory, and may be taken as settling the question of the contagiousness or non-contagious-ness of 1 *- footrot, about which so much controversy has centred. It seemed inexplicable that such keen observers as Youatt and Fleming, on the o.n.e hand, should pin their faith to its contagiousness, and that equally shrewd and experienced investigators like Dick and Williams should be convinced of its non-contagiousness. The former were swayed largely by their knowledge of the evidence of the contagiousness of a similar disease in France, where it is now known that contagious eczema' of the feet of sheep, so closely identical in its symptoms and effects with simple footrot, is very rampant. The issue was clouded somewhat by the fact that sheep suffer sometimes from the "foot and mouth disease" of cattle, and doubtless at times this extremely contagious disease was mistaken for footrot. The first correct note, as foreshadowing a reconciliation , of th,e diverse views that were held, was struck by Spooner, who considered the opinion that the disease was always, or even generally, contagious to be undoubtedly erroneous, "but who stated* his conviction that some outbreaks that he had experience of could not be explained otherwise than by contagion. Later on, Brown, who followed by researches which established the fact of the contagious nature of one form of disease, stated that this virulent form of footrot,, recognised generally on the continents of Europe and America, was not often observed in England. Hogg, the Ettrick shepherd, when he recorded that he had known simple driving of a flock over a particular farm cause footrot in the flock, must have encountered the contagious eczema and mistaken it for simple footrot. THE QUEENSLAND OUTBREAK. Similarly, it is likely that these outbreaks of so-called footrot which have been recorded at different times in Australia—particularly the Queensland outbreaks in the early nineties —and of Which there is abundant proof of contagiousness, were in reality a visitation of the eontagious foot eczema, which is closely allied to the contagious "foot and mouth disease" of cattle, but which possesses anatomical and other features whereby it may be comparatively easily distinguished from the more common and ordinary kind of footrot that is the bane of some localities in all seasons, and of additional localities in some seasons. It will be seen later that it is only in the lirst stages that the two diseases can be accurately distinguished, and that when established the lesions produced are practically alike. Colour has been lent to the arguments of those theorists who hold that all footrot is contagious by the circumstance that the disease occurs epizootically; that is, it affects a large number of sheep simultaneously or successively, but such occurrence is in many instances satisfactorily accounted f.or by the fact that the whole flock is placed under similar operating causes. The disease being contracted by sound sheep on being introduced amongst affected sheep proves nothing "more than that" what will act as a cause in one sheep will also act as a cause in others may be exposed to 1 it. Finally, in these 1 days of. germs and germseekers, the absence of any positive evidence of bacterial causation is; significant, for it is now necessary, when claiming a specific or contagious character for a disease, to affirm its bacterial nature by incontrovertible pnoof, and as regards the ordinary footrot this has not been done.

SIMPLE FOOTROT. Simple footrot can only, then, be considered contagious in the false sense thati a septic .wound or running sore may be contagious; that is, the caustic discharges and . horn scales from affected sheep, by being trampled and paddled upon by other sheep, and so brought into contact with the soft, tender horns between the toes (perhaps already inflamed and sore), may cause such irritation as will serve to set up inflammation of a character which fostered by the natural dirtiness of the situation, develops into footrot. While not at all likely to terminate fatally, footrot is, a source of heavy monetary loss to pastoralists, in that the pain and irritative fever which accompany moderately severe cases prevent that rapid growth and thriving condition which are essential to profitable sheep culture. The fleece suffers from the unthriftiness, and fattening is tardy for the -same reason, and also because there is disinclination to "forage" for the best "pickings."

NATURE AND CAUSES. Footrot is essentially . an inflammation of the tissues of the foot subjacent to the horn, varying in intensity from a mere erosion or sore to a sloughing ulceration, and caused by an injury of some kind. It is often primarily caused by a softening of the hovn of the feet, particularly that thin and naturally tender horn on the inner aspect of the claws, whereby it becomes greatly more prone to injury of any kind. It is hence particularly prevalent in low-lying, marshy, or undrained situations, where the feet are likely to be kept continuously soft and spongy. When in this state the slightest injury from rough grass, stubble, stones, or uneven ground, soon becomes a sore, and through inoculation with dirt and decomposing organic debris, ulceration and under-running of the horn with matter quickly follow. Footrot is also met with in sheep grazing on high, gravelly land, or which have travelled long distances, over hard ground, and in these cases the disease is

simply au extension of footsoreness. Again, when found on loose, sandy soils, its occurrence is due to the fact that on these soils there is little, wear of the horn; the claws become long and overgrown, and subsequently mechanically inflamed. As a general rule, the disease prevails most on moist land in wet weather, and on dry land in dry weather.

SYMPTOMS. Lameness or apparent difficulty in walking and frequent inclination to rest are first noticed; in a few days a hobbling, painful gait is accentuated, and the sheep begins to fall away in condition and assume a lank appearance. On examination the affected feet will be found to be hot and painful when pressed, and a moist, foul-smelling discharge will be noticed between the claws, the thin horn on the inner sides being swollen. Later on the soft tissues above and around the foot will become swollen and inflamed, and a strong pulse may be felt in the region; the discharge between the claws increases and becomes puru- ! lent (mattery); the horn becomes crumbly and disintegrated, being eaten away, as it were, by a kind of dry rot process, and the sore may spread until the whole of the side and under-surfacp of the claws becomes involved in ' the ulceration. The sensitive blood-vascu-lar laminae which secrete the horh are by this time exposed, and may produce fungus-like' growths (proud, flesh, really) which- bleed on the slightest touch, so forming along With the offensive discharge a soft scab, which rubs off easily. By this time the sheep has no inclination to walk; it '' scraffles'' along on its knees or its belly according as the fore or hind feet are affected, and, partly , from want of food and partly from febrile pain, soon becomes a lean, pitiable object. In extreme cases, the claws may be shed, but as a rule, with reasonable care and treatment, the more serious of the conditions above described are not experienced.

TREATMENT,

The object of treatment is primarily to render the parts clean and sweet, and keep them so by destroying the septic germs which are responsible for the spreading ulceration and irritating discharges, then to allay irritation, and finally to promote a healthy horn growth. To effect this, it will be necessary that, whatever application is used, it should be given a chance to get at the innermost and uttermost ramifications of the ulceration where the festering germs are, and . consequently the rough-and-ready inetliod adopted on' some stations of depending solely on foot-baths is often ineffective. It may do in the early stages when the disease has not under-run the horn, but if such has occurred all loose and under-run horn requires to be pared away, otherwise the medicament cannot reach the seat of the operations 6f the germs which it is intended to destroy.

Various agents have been used with su(?ee£s in treating footrot —butyr of antimony, nitric acid, creosote, carbolic acid, and many others. These are all antiseptic and caustic in their action, and perhaps the most consistently successful of them is butyr of antimony, which, when mixed with an equal proportion of tineture of myrrh, forms a firstrate footrot lotion to be kept in stock. This or other fluid dressing should be applied to the affected parts with a feather or brush, so that the adjacent skin is not needlessly burnt.

PROMPTNESS ESSENTIAL,

When footrot has become established in a flock the treatment should be prompt, methodical, and thorough if heavy monetary loss is to be avoided. The flock should be yarded, and all sheep showing the slightest halting or lameness, should be caught. and turned,' their - feet examined, and the necessary paring, to expose the sores and shape the claws, cleanly and-thoroughly done. To be on the safe side, tlie whole flock 'should be gone through in this way once at least, if practicable. The sheep should then be turned directly into a race foot-bath, about 10ft or 15ft long, and aliowed to pass loiteringly through on to dry ground. An arsenic solution is generally used for the bath, and it is effective if the paring has been sufficiently thorough. It is made by boiling together 21b of white arsenic and 31b of carbonate of potash (or 41b of washing soda) in 14 gallons of water until all the arsenic is dissolved. The solution is placed in the bath to a depth of 2in, and replenished as required. The procedure may require to be repeated two or three times, at intervals of a fortnight. Recently I had'occasion'to suggest a line of treatment' for a foot-rotted flock, and a solution of formalin as. a foot-bath, followed by paddling on quick-lime, was "adopted with , great success. Sehering's formalin was used in the proportion of 1 to 50 of w&ter (51b of formalin, costing 8/-, to 25 gallons of cold water), and the sheep were passed from the foot-bath along a wooden platform on to a hard floor of a woolshed, which had been covered to a depth of about an inch with powdered quicklime. On this the sheep were allowed to paddle for an hour or' two, and when turned out on to a dry, bare paddock they carried with them caked on the diseased feet a packing of antiseptic and caustic quicklime, which so promoted healing that it was only necessary to repeat the procedure once again at the end of ten days. Special treatment will require to be adopted in the case of individual sheep badly affected. After paring and cleansing, * the raw surfaces should be canterised with burnt alum nitrate of silver (lunar caustic,), or bluestone, or chromic acid, to reduce the soft, fungoid growths and to stimulate the formation of healthy horn. They should then be given a dressing with Stockholm tar, which, in addition to being antiseptic, forms an adhesive covering to protect the sores; in many cases it is advisable to protect the dressed feet from dirt and air by bandaging, or applying a specially-made "stool," to be tied on with tapes, and which will also help to keep the dressings in / position. As improvement takes, place the above strong caustics should be discontinued, and the milder stock lotion previously mentioned applied. It must be borne in mind that treating the disease without removing the conditions which promote it will always be unsatisfactory. A change of pasturage, whether from wet, boggy land, or. from soft or gravelly country, according as

each may have been use, is always advisable.

CONTAGIOUS FOOT ECZEMA

The differential diagnosis of this afFec-tion from simple footrot can only be made in the early stages, and depends upon observation of the starting place of the disease. In this disease the first tenderness, heat, and swelling occurs round the coronet at the junction of the horn and skin. This is followed.by the formation of a ring of soft, spongy, crumbly horn near the coronet, and the disease then spreads to between the claws and other parts of the foot'. From this out, mainly on account of the parts becoming infected with dirt or septic matter from the ground, the progress of the disease and the appearances and symptoms resemble ordinary footrot, except that there is usually more swelling of the tissues above the claws, and there is a tendency for the claws to slough off. The local treatment for the affection should be the same as that advised for simple footrot, but the stronger caustics are not usually required.

INFLAMMATION OF THE INTERDIGITAL DUCT.

Situated in the skin between and just above the claws in front is the opening of a duct, called the inter-digital or inter-ungulate duct, which leads from a small gland situated between the pastern bones. The gland, secretes a semisolid oily substance of a greenish opalescent hue, which _s conveyed by the duct and is discharged on to the delicate skin and horn between the claws, which are thereby lubricated and protected from wet and dirt and friction. On soft, clayey land, and oh gravelly land, the " duct opening is liable to become blocked with mud or grit, and two untoward results may follow—the teiider skin and horn, being unprptected, may become dry, irritated, and inflamed, and the duct itself may be L come inflamed by the irritation of the foreign body blocking it. In either or in both of these events the inflammation soon involves the soft structures beneath the horn, and again, from inoculation with septic matter and dirt, the sequence of all the: progressive stages of footrot may be commenced. When blocking or inflammation of the duct is obseiyed in the early stages, the cutting away of the blocked portion or the slitting of the duct and removal of the foreign body will, usually result' in recovery. Otherwise the treatment to be followed isVthat previously outlined. • ... .