Information AboutLaminitis |
| CATEGORIES ABOUT LAMINITIS | |
| equine injury and lameness | |
| equine hoof | |
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Laminitis is inflammation of the sensitive Laminae of the foot in a horse, the complications of which sometimes result in the horse having to be euthanized. The front hooves are most commonly affected, although the hind feet are sometimes affected. Related to laminitis is foundering, Founder (from the naval term 'to sink') results when there is a cataclysmic failure of the interdigitation between the sensitive and insensitive laminae around the entire perimeter of the hoof. Apparently this event allows the entire bony column, often described by its most distal bone, the third phalanx(aka: PIII, coffin bone, pedal bone)) to sink to the bottom of the hoof capsule. In fact it is not the coffin bone that's being pushed down in a sinker case, it is the hoofcapsule being pushed up that really describes the situation. When the coffin bone lost it's connection to the hoofwall because of this massive damage to the laminae, the existing hoofcapsule will act as a tourniquet, when being pushed up. At best bloodflow will be severely restricted, limiting chances of a favourable outcome to a very low percentage. When the damage to the laminae is less severe, damage will show up at the spot where traction is at it's peak, in the toe area of the foot. A likely reason for this is the pull of the tendon attached to the coffin bone, the deep flexor tendon, literally pulling the dorsal face of the coffin bone away from the inside of the hoofwall. It is also theorized that the body weight of the animal contributes to rotation of the coffin bone. Rotation results in an obvious misalignment between PII(the short pastern bone and PIII(the coffin bone/pedal bone). In some cases, the rotation may also result in PIII penetrating the sole and being exposed externally. Depending on the severity at the onset of the pathology, there may be rotation only, sinking only or a combination of both. All in various degrees of severity. It is generally agreed that a severe "sinker" warrants the gravest prognosis and is will often lead to euthansia of the patient. Not all horses that experience laminitis will founder, but all horses that founder systemically will first experience laminitis. In laminitis cases a clear distinction must be made between the acute situation starting at the onset of a laminitis attack and a chronic situation. A chronic situation can be stable and unstable. A stable chronic laminitic horse will, when left untreated, end up with a severly distorted hoofcapsule as a result of comprised growth centers. The difference between acute, chronic, stable and unstable is of vital importantance when choosing a treatment protocol. Founder can be mechanical or systemic, unilateral (on one foot) or bilateral (on two feet). Laminitis can occur a all four feet also. Systemic founder is associated with laminitis and is resultant of the partial dysfunction of the epidermal and dermal laminae which attach the distal phalanx to the hoof wall. With dysfunction, the deep digital flexor tendon (which attaches to the semi-luner crest of the distal phalanx and serves to flex the foot) pulls the bone away from the wall instead of flexing the foot. When the coffin bone is pulled away from the hoofwall the remaining laminae will tear. The veins supplying those laminae of blood rupture and blood mixes with already ischemic (dead) cells. This will inevitably lead to abcesses within the hoofcapsule that can be severe and very painfull. When left untreated a laminar wedge will occur at the spot where the coffin bone got torn away from the hoofwall. This laminar wedge may in some cases prevent the renewed attachment of the laminae to both the hoofwall and the hoofwall. When this is obvious, the dorsal hoofwall should be resected (removed). Systemic founder is usually bilateral and most common in fronts, although it sometimes affects hinds. Mechanical founder, commonly called "road founder" does not initially involve laminitis or rotation of the distal phalanx; instead the wall is pulled away from the bone or lost. Mechanical founder can occur when a horse habitually paws, is ridden/driven on hard surfaces, or loses laminar function due to injury or pathologies affecting the wall. Mechanical founder can be either unilateral or bilateral and can affect both fronts and hinds. It is important to note that in some cases, once the distal phalanx rotates, it cannot be literally "de-rotated" as such. However by trimming one can change the position of the hoofcapsule and thus the position of the coffin bone within that hoofcapsule. When at least the coffin bone has a normal position in relation to the other phalanxes in the equine digit (the short pastern bone and the long pastern bone) a better healing enviroment is created. Greatly improving chances on recovery of the animal. Successful treatment for any type of founder must necessarily involve stabilization of the bony column by some means. Stabilization can take many forms, but most include trimming the hoof to facilitate turnover and trimming the heels to insure frog pressure. While some horses stabilize if left barefooted, the most successful methods of treating founder involve positive stabilitation of the distal phalanx by mechanical means: shoes, pads, polymeric support, etc. Steps taken to stabilize the bony column gain maximum effect when combined with steps that will reduce the pulling force of the flexor tendon attached to the coffin bone, the deep flexor tendon. __NOTOC__ CAUSES OF LAMINITIS Many cases of laminitis are caused by more than one cause and are rather due to a combination of causes. Common causes include: # Carbohydrate overload # Hard ground # Lush pastures # Untreated infections # Colic # Lameness # Cushings disease # Peripheral Cushings disease Carbohydrate overload If a horse is given grain in excess,or eats grass that is under stress and has accumulated excess Non Structural Carbohydrates, (sugar, starch or fructan) this results in the horse being unable to digest all of the carbohydrate in the foregut. The excess then moves on to the hindgut, and ferments in the cecum. The presence of this fermenting carbohydrate in the cecum causes proliferation of lactic acid bacteria, and an increase in acidity. This kills beneficial bacteria which ferment fiber. The endotoxins and exotoxins may then absorbed into the bloodstream, due to a 'leaky gut syndrom' caused by irritation of the gut lining by increased acidity. Circulation is restricted, particularly in the feet. This results in laminitis. Laminitis can also be cause by insulin resistance in the horse. Insulin resistant horses tend to get obese very easily, and even when starved down may have abnormal fat deposits on the neck, shoulders, loin, above the eyes, around the tail head, even when the rest of the body is in normal condition. The mechanism by which laminitis associated with insulin resistance is not understood, but seems to be triggered by sugar and starch in the diet of susceptible individuals. Ponies and breeds that evolved in harsh environments with only sparse grass tend to be more insulin resistant, possibly as a survival mechanism. Insulin resistant animals may get laminitis from only very small amounts of grain or high sugar grass. Slow adaptation to pasture will not work as it does to prevent laminitis via microbial population upsets. Insulin resistant horses with laminitis should be removed from all green grass, and be fed only hay that is tested for Non Structual Carbs (sugar, starch and fructan) and found to be below 11% NSC on a dry matter basis. Soaking hay underwater may remove excess carbs and should be part of a first aid treatment for any horse with laminitis associated with obesity or abnormal fat deposits. Hard ground Whenever possible, avoid working horses on hard ground. This includes concrete or gravel roads. An indoor or outdoor arena should be periodically dragged with a rake to loosen the soil and prevent it from hardening. Hard surfaces increase the concussion upon the horse's feet. The greater and more prolonged the concussion, the more likely it is that the horse will contract laminitis. Lush pastures When releasing horses back into a pasture after being kept inside (typically during the transition from winter stabling to spring outdoor keeping), it is important to reintroduce them gradually. Feed horses before turning them out, and limit the amount of time outside (45 minutes to an hour at first, gradually increasing the amount of time) and decrease the amount fed them beforehand as the season progresses. If a horse consumes too much lush pasture after a diet of dry hay, the excess carbohydrate of grass can be a shock to its digestive system. If the horse is fed beforehand, it will not eat as much fresh grass when turned out and will be less likely to founder. Untreated infections Infections, particularly where caused by Bacteria , can cause release of Endotoxins into the blood stream which may trigger laminitis. A retained Placenta is a renowned cause of laminitis. Colic Laminitis can sometimes develop after a serious case of colic due to the release of Endotoxins into the blood stream. (See Horse Colic .) Lameness Lameness causes a horse to favor the injured leg, resulting in uneven weight distribution. This results in more stress on the healthy legs, and can result in laminitis. Cushings disease Cushings Disease is common in older horses and ponies and causes an increased predisposition to laminitis. Peripheral Cushings disease Peripheral Cushings disease is an area of much new research and is increasingly believed to have a major role in laminitis. It involves many factors such as Cortisone metabolism and Insulin resistance. It has some similarities to Type II Diabetes in humans. SYMPTOMS OF LAMINITIS # Increased temperature of the wall, sole, and/or coronary band of the foot. # A pounding pulse in the digital palmar artery. (The pulse is very faint or undetectable in a cold horse, readily evident after hard exercise.) # Anxiety # Visible trembling # Increased vital signs and body temperature # Sweating # Flared Nostrils # Walking very tenderly, as if walking on egg shells # The horse standing in a "founder stance" (the horse will attempt to decrease the load on the affected feet. If it has laminitis in the front hooves, it will bring its hindlegs underneath its body and put its forelegs out in front.) COMPLICATIONS OF LAMINITIS Separation of the hoof wall The destruction of the sensitive laminae results in the hoof wall becoming separated from the rest of the hoof. Pus may leak out at the white line or at the coronary band. Rotation of the third phalanx The third phalanx, also known as the coffin bone, rotates downward. Normally, the third phalanx should be parallel to the hoof wall, but in laminitis the tension of the deep digital flexor tendon allows the coffin bone to rotate. The degree of rotation is often determined by when laminitis is detected in the horse, and how soon actions are taken to treat the horse. Penetration of the third phalanx through the sole If rotation of the third phalanx continues, it can eventually penetrate the sole of the foot. Penetration of the sole is not fatal; many horses have been returned to service by aggressive treatment by a veterinarian and farrier, but the treatment is time-consuming, difficult and expensive. TREATMENT There is no cure for a lamenitic episode; in fact, many go undetected. However, a horse can live with laminitis for many years, and with proper care and corrective shoeing, may still be able to bear a rider. Plenty of rest and corrective shoeing by a competent Farrier can help improve a horse's condition, and a horse may completely recover if the laminitis was not severe. There are several techniques to treat laminitis. Two main streams can be detected. One developed by the late world-renowned farrier Burney Chapman, of Texas USA, another by the veterinarian-farrier Ric Redden of Kentucky, USA. On both information can be found on the web and in various published articles. Every successful method of treatment requires a competent farrier and veterinarian and success is not guaranteed. RECENT UPDATES: THE BAREFOOT MOVEMENT POINT OF VIEW After the studies on hoof health by . For a comparison of the efficacy of various protocols, see any edition of Stashak's "Adams Lameness in Horses" or Rooney's, "The Lame Horse"; both are standard veterinary texts. Additionally, www.hopeforsoundness.com offers a proven successful protocol that involves both correct trimming and the application of specific orthotics to manage and remediate the pathology. SUGGESTED READING
EXTERNAL LINKS link title {Link without Title} Laminitis information resource {Link without Title} Safergrass.org Current research on prevention and treatment of laminitis {Link without Title} www.horseshoes.com, field experts sharing knowledge, Keywords: founder, laminitis {Link without Title} Hope for soundness.com {Link without Title} Laminitisresearch.org, presentation of research by C.C. Pollit and his team |
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