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== Introduction ==

== Introduction ==

Laminits is a common and debilitating condition of horses cause by '''separation of the laminae of the hoof'''. It can be acute or chronic and can result in the horse being put down. To revise the anatomy of the hoof see [[Equine Phalanges - Anatomy & Physiology]]

Laminits is a common and debilitating condition of horses caused by '''separation of the laminae of the [[Hoof - Anatomy & Physiology|hoof]]'''. It can be acute or chronic and can result in the horse being put down.  

== Aetiology ==

== Aetiology ==

Laminitis is an '''acute degeneration''' of the '''sensitive primary and secondary Laminae'''. The cause for this is unknown.

Laminitis is an '''acute degeneration''' of the '''sensitive primary and secondary laminae'''. The cause for this is unknown.

== Epidemiology==

== Epidemiology==

* Obesity

* Obesity

* Access to lush pastures - particularly in the Spring or Autumn, on cold bright days, and during daylight hours with levels of fructans are highest

* Access to lush pastures - particularly in the Spring or Autumn, on cold bright days, and during daylight hours when levels of fructans are highest

* Grain overload (Ingestion of large quantities of soluble carbohydrates)

* [[Grain Overload - Horse|Grain overload]] (ingestion of large quantities of soluble carbohydrates)

* Retained Placenta, [[Colic|colic]], diarrhoea and any other systemic illness causing endotoxaemia

* Retained placenta, [[Colic|colic]], diarrhoea and any other systemic illness causing endotoxaemia

* Animals having little exercise

* Animals having little exercise

* Pituitary Pars Intermedia Dysfunction / Equine Cushing's

* Pituitary Pars Intermedia Dysfunction / Equine Cushing's

* Equine Metabolic Syndrome

* [[Equine Metabolic Syndrome]]

* Trauma/excessive work on hard surfaces

* Trauma/excessive work on hard surfaces

* Increased weight bearing on one limb - normally caused by lameness in the contralateral limb.

* Increased weight bearing on one limb - normally caused by lameness in the contralateral limb.

== Pathogenesis ==

== Pathogenesis ==

[[File:Founder_severe_rotation.JPG|right|thumb|200px|Severe pedal bone rotation with penetration into the hoof sole (Wikimedia Commons)]]

[[File:Founder_severe_rotation.JPG|right|thumb|200px|Severe pedal bone rotation with penetration into the hoof sole (Wikimedia Commons)]]

The separation of the sensitive laminae (originated from the third phalanx/pedal bone) from the laminae lining the inside surface of the hoof.

The separation of the sensitive laminae (originated from the third phalanx/pedal bone) from the laminae lining the inside surface of the hoof is followed by the pedal bone '''rotating''' within the '''hoof capsule''' and coming to '''rest on the sole'''. This causes the sole to be pushed downwards and the pedal bone may penetrate the sole at the toe. Rotation occurs due to '''torque''' from the '''deep digital flexor tendon'''. Another possibility is that he pedal bone ''sinks''' (displaces ventrally) due to the weight of the animal. The bone may rotate, sink or both. Serum accumulates in the space between the laminae and can breakdown the white line.

This allows the pedal bone to '''rotate''' within the '''hoof capsule''' and come to '''rest on the sole'''. This causes the sole to be pushed downwards and at the toe the pedal bone may penetrate the sole.

Rotation occurs due to '''torque''' from the '''deep digital flexor tendon'''.

Also due to the weight of the animal the pedal bone can '''sink''' (displace ventrally). The bone may rotate, sink or both.

Serum accumulates in the space between the laminae and can breakdown the white line.

=== Mechanism of Separation of the Laminae ===

=== Mechanism of Separation of the Laminae ===

(3) '''Enzymatic digestion''' of laminae by Matrix Metalloproteins (MMPs)

(3) '''Enzymatic digestion''' of laminae by Matrix Metalloproteins (MMPs)

(4) '''Abnormalities in the hoof metabolism or corticosteriods''' (Endogenous cortisol or iatrogenic) which results in increased glucocorticoid activity.

(4) '''Abnormalities in the hoof metabolism or corticosteriods''' (endogenous cortisol or iatrogenic) which results in increased glucocorticoid activity.

Subsequent to separation of the laminae a '''pain-hypertension-vasoconstiction''' cycle will occur in acute cases. '''Pain''' causes the release of '''vasoconstictors''' such as catecholamines, angiotensin II, and vasopressin. This vasoconstriction then causes a '''reduced blood flow to the foot''' and systemic hypertension.

Subsequent to separation of the laminae a '''pain-hypertension-vasoconstiction''' cycle will occur in acute cases. '''Pain''' causes the release of '''vasoconstictors''' such as catecholamines, [[Renin Angiotensin Aldosterone System|angiotensin II]], and [[Pituitary Gland - Anatomy & Physiology#Antidiuretic Hormone|vasopressin]]. This vasoconstriction then causes a '''reduced blood flow to the foot''' and [[Systemic Hypertension|systemic hypertension]].

== Clinical Signs ==

== Clinical Signs ==

=== Radiography ===

=== Radiography ===

[[File:Laminitic.jpg|right|thumb|200px|Radiograph of the laminitic foot (Wikimedia Commons)]]

[[File:Laminitic.jpg|right|thumb|200px|Radiograph of the laminitic foot (Wikimedia Commons)]]

Radiographs should be taken of front feet or all feet if all legs are affected. A '''metal strip''' should be placed on the '''dorsal wall''' of the hoof and the '''sole''' should be maked with a similar metal strip or a pin can be used. They the angle of the pedal bone in relation to the hoof can then be analysed. There may be no radiographic changes if the case is acute or mild. However, radiographs in more severe cases radiographs may show:  

Radiographs should be taken of front feet or all feet if all legs are affected. A '''metal strip''' should be placed on the '''dorsal wall''' of the hoof and the '''sole''' should be marked with a similar metal strip or a pin can be used. They allow for the angle of the pedal bone in relation to the hoof to be analysed. There may be no radiographic changes if the case is acute or mild. However, in more severe cases radiographs may show:  

* '''Rotation''' of the pedal bone as a tilting of the distal aspect towards the sole

* '''Rotation''' of the pedal bone as a tilting of the distal aspect towards the sole

* '''Sinking''' of the pedal bone (which is the main indicator of prognosis).

* '''Sinking''' of the pedal bone (which is the main indicator of prognosis).

'''Serum''' build up may be evident as a '''radiolucent line''' between the dorsal hoof wall and the pedal bone. In chronic cases the pedal bone may even develop the appearance of a '''Turkish slipper''', as a result of the pressure placed on tip of the rotated P3.  

*'''Serum''' build up may be evident as a '''radiolucent line''' between the dorsal hoof wall and the pedal bone.  

*In chronic cases the pedal bone may even develop the appearance of a '''Turkish slipper''', as a result of the pressure placed on tip of the rotated P3.  

You should measure:

You should measure:

* Equine Rhabdomyolysis Syndrome

* Equine Rhabdomyolysis Syndrome

* [[Clostridium tetani|Tetanus]]

* [[Clostridium tetani|Tetanus]]

* Colic

* [[:Category:Colic in Horses|Colic]]

* Spinal Ataxia

* Spinal Ataxia

'''Analgesics''', mainly [[NSAIDs]] (Phenylbutazone) and '''box rest''' are the standard treatments. Other available NSAIDs are Flunixin Meglumine, Ketoprofen and Dimethyl Sulfoxide.  

'''Analgesics''', mainly [[NSAIDs]] (Phenylbutazone) and '''box rest''' are the standard treatments. Other available NSAIDs are Flunixin Meglumine, Ketoprofen and Dimethyl Sulfoxide.  

As the pathogenesis of laminitis is not fully understood there is some controversy surrounding the use of some drugs and the theories behind their use - such as vasodilators and anticoagulants. Therefore it is up the individual clinician to decide whether these drugs are indicated. However it is unanimously agreed the box rest and anti-inflammatory drugs are the mainstays of treatment.

As the pathogenesis of laminitis is not fully understood there is some controversy surrounding the use of some drugs and the theories behind their use - such as vasodilators and anticoagulants. Therefore it is up the individual clinician to decide whether these drugs are indicated. However it is unanimously agreed that box rest and anti-inflammatory drugs are the mainstays of treatment.

'''Mechanical support''' is important and may provide some '''pain relief''' and help '''prevent rotation or sinking of the pedal bone'''. It can be done with '''polystyrene''' or other '''packing materials''' or by keeping the animal on '''soft, deep bedding'''. Elevating the '''heel''' with a '''wedge''' or wedge shoe may be useful to take off some of the strain on the deep digital flexor tendon and help to reduce rotation. '''Remedial farriery''' can be used to minimise the detrimental effects of disease by; stabilising the pedal bone, decreasing the forces placed on the dorsal laminae, removing infection, and improving blood supply and growth. Techniques include the use of trimming and egg bar, heart bar and plastic shoes. Numerous trimmings will be required.

'''Mechanical support''' is important and may provide some '''pain relief''' and help '''prevent rotation or sinking of the pedal bone'''. It can be done with '''polystyrene''' or other '''packing materials''' or by keeping the animal on '''soft, deep bedding'''. Elevating the '''heel''' with a '''wedge''' or wedge shoe may be useful to take off some of the strain on the deep digital flexor tendon and help to reduce rotation. '''Remedial farriery''' can be used to minimise the detrimental effects of disease by; stabilising the pedal bone, decreasing the forces placed on the dorsal laminae, removing infection, and improving blood supply and growth. Techniques include the use of trimming and egg bar, heart bar and plastic shoes. Numerous trimmings will be required.

Identification and management of any '''predisposing factors''' is extremely important in preventing the recurrence of laminitis.  

Identification and management of any '''predisposing factors''' is extremely important in preventing the recurrence of laminitis.  

Overweight and unfit animals should be managed appropriately with diet and exercise changes. Horses with a history of laminitis should not be allowed to graze lush pasture, especially in Spring and Autumn and early in the morning. Following injury or lameness to one limb, the other limbs should be monitored closely for signs of laminitis (increased heat and digital pulses) and the animal placed on a deep bed to help prevent it occuring. In horses where endotoxaemia may develop, anti-endotoxic drugs such as NSAIDS should be given as they may prevent the development of laminitis. As mentioned, in the cases where an underlying disease is suspected, this should be identified and treated appropriately.

Overweight and unfit animals should be managed appropriately with diet and exercise changes. Horses with a history of laminitis should not be allowed to graze lush pasture, especially in Spring and Autumn and early in the morning. Following injury or lameness to one limb, the other limbs should be monitored closely for signs of laminitis (increased heat and digital pulses) and the animal placed on a deep bed to help prevent it occurring. In horses where endotoxaemia may develop, anti-endotoxic drugs such as NSAIDS should be given as they may prevent the development of laminitis. As mentioned, in the cases where an underlying disease is suspected, this should be identified and treated appropriately.

== Prognosis ==

== Prognosis ==

RVC staff (2009) '''Locomotor System''' RVC Intergrated BVetMed Course, ''Royal Veterinary College''

RVC staff (2009) '''Locomotor System''' RVC Intergrated BVetMed Course, ''Royal Veterinary College''

[[Category:Musculoskeletal Diseases - Horse]]

[[Category:Musculoskeletal Diseases - Horse]]

[[Category:To Do - Manson]]

[[Category:Dermatological Diseases - Horse]]

[[Category: To Do - Siobhan Brade]]

[[Category:Expert Review - Horse]]

[[Category:To Do - Manson review]]