CRACKED HEELS IN HORSES. SCRATCHES.
Special susceptibility and exposure of posterior pastern region. Divisions. Causes: local irritants, decomposing manure, chill water, slush, mud, pools of liquid manure, septic irritation, stones, sand, lime in mud, salted snow or ice, washing heels, caustic soaps, stubble, clipped or singed hair, stocking of limbs, lymphangitis, sprains, arthritis, anæmia, cardiac, urinary or hepatic disease, parasites, heavy bedding, constitutional predisposition. Symptoms: redness, heat, tenderness, swollen, erect hairs, lameness, knuckling, or exudate, crusts, scabs, abrasions, chaps, fissures, ulcers, loss of pliancy, engorgment of limbs, fœtid secretion. Prognosis according to cause. Treatment: remove causes, give rest, cleanse limb and stable, astringent antiseptic lotions, sulphurous acid, carbolic acid, creolin, lysol, pyoktannin, chrysophanic acid, moderate laxative food, diuretics, arsenic, bandaging, hand rubbing, exercise.
The affections of the heel or posterior part of the pastern in horses are largely modified by the anatomical character of the skin in this region, and the special exposure to inimical agents, so that it is convenient to consider them under special headings, even though the eruption may be of the same kind with that seen in other parts. The dermatitis of this region, which are not primarily contagious may be conveniently divided into 1st, such as are unattended with free secretion, and 2d, those that implicate the sebaceous glands and are marked by an offensive discharge. Cracked heels belong to the former category.
The causes are extremely varied, consisting in the application of irritants of many kinds, to the susceptible skin in a system too often already predisposed to skin disease.
Standing on reeking dungheaps, or on heating manure in filthy stalls subjects the heels, and especially the hind ones, to ammonia and other irritating fumes, and when taken out to the cold air, chill water and mud, the sensitive parts suffer. Again in the farm yard and even in neglected stalls the hind feet are immersed in pools of liquid manure, the ferments and toxic matters of which dry on the skin, attack the surface and determine septic congestions and inflammations. On country roads where there is no pretense of pavements, or macadam, the mud in spring and fall is a source of great irritation on certain soils which contain small flat stones, pebbles or sand, or in which lime or decomposing manure is a prominent feature. Standing in snow or slush, especially if chilled by salting, produces partial or complete congelation with the result of chillblains or even more active and destructive inflammation or sloughing. The habit of washing the heels and allowing them to dry spontaneously in the stall is only less injurious by the chill induced. This is still further aggravated by the use of caustic soaps on the already tender skin. The lighter breeds of horses, devoid of long hair on the pasterns, though less subject to the greasy secretion, are even more exposed to chills and direct injuries, and suffer readily and often persistently from erythema and cracks. In many cases trouble comes from the ends of stubble and other vegetables acting on the skin. A common fault is the close clipping and even singeing of the hair in the hollow of the heel. The stiff, bristly ends of the hairs on one fold of the pastern continually prick the skin of the adjacent fold when the animal is in motion and not only is this irritating to the healthy skin, but it becomes incomparably more so when that is congested and tender. Even in summer the deep dust on unpaved roads, mixing with the normal secretions of the heel, rolls into semi-solid masses between the folds and proves the more irritating, the greater the admixture of sand or solid bodies. A common cause is the stocking of the limbs, with the attendant congestion, distension and debility of the skin. This may be due in its turn to a great variety of proximate or remote causes, lymphangitis, sprains, arthritis, osteitis, anæmia, cardiac, urinary or hepatic disorder, parasitisms, etc., so that accessory causes must often be widely sought. Even an excess of straw around the hind limbs will cause stocking in some animals which escape on bare pavement. Finally we must take into account that constitutional predisposition in some animals that makes them liable to inveterate skin diseases under the slightest causes.
Symptoms. In the milder forms there may appear a redness, with heat, tenderness and swelling in the hollow of the pastern, the hairs stand stiffly erect, and the surface may be perfectly dry. The affected limb has the pastern more upright than the others and the fetlock starts slightly forward. In a nervous, sensitive horse the skin is so tender and rigid, that the animal can hardly be persuaded to use the limb, and goes dead lame for a considerable distance until it has become more pliant.
With some aggravation of the condition the skin is felt to be somewhat rough and uneven by reason of the encrustations of epidermis, dried secretions and dust over its surface, which may convey to the finger a slightly oily sensation. In many cases these epidermic and exudation products form scabby elevations, and a chronic condition of this kind may persist indefinitely, constituting what is known in America as scratches. This will vary by reason of the detachment of these concretions with the formation of abrasions and sores of various sizes, which may heal, or extend by coalescence, chapping, or ulceration.
In other cases, even at an early stage, the formation of chaps or cracks is a marked feature. At times this may seem to be the result of over distension in the inflamed superficial layers of the skin which have lost their natural pliancy and cohesion. They will, sometimes, form under slight exercise, but not when at rest. They may simply extend through the epidermis, exposing the papillary layer, or in bad cases one or more fissures may extend through the integument and expose the tendons beneath. They may extend forward on the sides of the pastern or upward over the back of the fetlock and metatarsus.
In all cases, when the local inflammation is acute, some swelling of the limbs appears, and this keeps pace with the character and extent of the trouble. With extensive chaps or fissures it becomes extreme, extending up toward the hocks and attended by great pain and stiffness. The sores become the seat of active suppuration, with it may be considerable destruction of tissue. Even in the milder forms there may often be seen a fœtid muco-purulent secretion in the depth of the folds of the pastern, and in the worst cases this extends to the whole surface after the manner of grease.
Prognosis. The milder uncomplicated cases recover readily and perfectly under rest and judicious treatment; the more advanced cases are liable to leave swelled legs with susceptibility to a relapse, and in cases associated with a constitutional diathesis or chronic internal disease, recovery may become problematical and uncertain.