FOOTROT IN SHEEP

New Zealand Mail, Issue 1681, 18 May 1904, Page 64

FOOTROT IN SHEEP

(By S. S. Cameron, M.R.C.V.S. in the ‘‘Pastoralists’ Review.”) During the present season reports have come to Hand to the effect that* footrot is more than usually common in different districts throughout the Commonwealth. It is, therefore, 'opportune that the subject should be dealt with; as well on account of the increased' prevalence as because, although the dry season is the best in which to tackle the job of eradication, there is yet time in most parts before the wet weather sets in to get affected liocks Comparatively free from the disease, and with their feet hard and tough sp as to be able to withstand the slushy, muddy, and yielding condition of the surfaces of paddocks throughout the winter. The reason for the extraordinary prevalence of footrot this year is doubtless, to be fotind in the abnormal wetness of the season, whereby the ground has remained in a moist condition eminently suited to bring about that unhealthy condition of the horn of the feet which is a commonly necessary prelude to. the contraction of the disease. NATURE OP THE DISEASE. 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.:—(l) Simple footrot, the ordinary widespread hon-contagious form; \2) contagious foot eczema, or eczema epizootica the ‘"mal de pied" of the French; and (3) inflamma-. tiofl of the interdigital duct. Such a conclusion is satisfactory and may be taken as settling the question of the contagiousness or non-cantagioushess of footrot, about which so much controversy has centred. It seemed inexplicable that such keen observers as Youatt and Fleming, on the one hand, should pin their faith to * its contagiousness, and that equally shrewd ana experienced investigators like Dick and Williams should be convinced bf its non-contagiousness.- The former school were swayed largely by their knowledge of the evidence of the contagiousness of a similar disease in France, where it is how 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. il'lie first correct note, as foreshadowing a reconciliation of ihe diverse views that \Vere 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 ne had experience of could not be explained otherwise than by contagion. Later on. Brown, wflo 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 Eiurope and America, was npt often onserved in England. Hogg, the Ettrick stiepherd, when he recorded that he had known sinrole 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. *• ■Similarly, it is likely that those 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., contagious foot eczema, which is cjosely allied to the contagious ' foot and mouthy 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, such as the present. It will be seen later that it is only in the first 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 mimber of sheep simultaneously or successively, but such occurrence is in many instances satisfactorily accounted for by the fact that the whole flock is placed under similar operating causes. The disease being, aontracted 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 that may be exposed to it. Finally, in these 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 proof, 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 that 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 aheep, and so brought in contact with the soft, tender horn between the tjoes (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, nevertheless, a source of heavy monetary losses to pastoralists in that the pain and irritative fever which accompany moderately severe cases prevent that rapid growth and thriving condition which is essential to profitable sheen oulture. 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 “picking.”

NATURE AMD 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 tQ a sloughing ulceration and caused by an injury of some kind. ItTs often primarily caused by. a softening of the horn 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 an extension of footsoreness. „ Again, when found or loose, -sandy soil, 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 ior apparent difficulty in walking and frequent inclination to rest are first noticed; in a few days the 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 flora on the inner sides being swollen. Later on the soft tissues above and around tne foot will become swollen and inflamed, and a strong pulse may be felt in the region; the discharge uetween the claws increases and becomes purulent (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 aiid under-surface of the claws become inv< iVi-d in the ulceration. The sensitive blood-vascular laminae which secrete the horn 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 belly according as the fore or hind feet are affected, and. partly from -want of food and partly from febrile pain, sioon 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 uf 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 o>nsequently the rough-and-ready method 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 io>ose and under-run horn requires to be pared away, otherwise the medicament cannot reach the seat of the operations of the germs which it is intended to destroy. Various agents, .have beer used with success in treating footrot —butyr of -antimony, nitric acid', creosote, carbolic acid, arsenic and many others. These are all antiseptics 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 tincture of myrrh, forms a firstrate footrot lotion to be kept in stock. This or other fluid application should be applied to the affected parts with a feather or brush, so that the adjacent skin is not needlessly burnt. When footrot has become established in a liock 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 the 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 10 or 15ft long, and allowed to pass loiteringly through on to dry ground. An arsenic solution is generally used for the bath, aud it is effective if the paring has been sufficiently thorough. It is made by boiling together 2lbs of white arsenic and 31bs of carbonate of potash (or 4lbs of washing soda) in 14 gallons of water until all the arsenic is dissolved. This solution is placed in the bath hy 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 footrotted ffock, and a solution of formalin as a foot-bath, followed by paddling on quick-lime, was adopted with great success. Sobering's formalin was used in the proportion of 1 to 50 of water (51bs of formalin, costing Bs, to 25 gallons of cold water), and the sheep were passed from the foot-bath along a wooden platform on to the hard floor of a woolshed. which had been covered to a depth of about an inch with powdered quicklime. On this the sheep were to paddle for an hour or two, and when turned our 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 ne-

cessary to repeat the procedure once again at the end of ten days. SPECIAL TREATMENT will require to be adopted in the casa of individual sheep badly affected. After paring and cleansing, the raw surfaces should be cauterised 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, Lind which will also help to keep the dressings in position. As improvement takes place the above stfong 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 in use. is always advisable. CONTAGIOUS FOOT-ECZEMA. The differential diagnosis of this affection 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 thft 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 tp 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 interungulate duct, which leads from a small gland situated between the pastern bones. The gland secretes a semi-solid oily substance of a greenish opalescent hue, which is conveyed by the duct and is discharged on to tfle delicate skin and horn between the claws, which are thereby lubricated and protected from wet and dirt and friction. On soft, clayey land, and on gravelly land, the duct opening is liable to become blocked with mud or grit, aud two untoward results may follow—the tender skin and horn, being unprotected, may become dry, irritated, and inflamed, and the duct itself may become inflamed by the irritation of the foreign body blocking it. In either or in both of these events ■che 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 observed 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 bo followed is that previously outlined.