1. Laminitis is the second highest cause of euthanasia in horses!!
Colic is the number one cause of euthanasia in horses.
Laminitis is the second highest cause of euthanasia in horses!!

2. Laminitis in the Thoroughbred Industry
Secretariat (1973 Triple Crown Winner)
Barbaro
(2006 KY Derby Winner)
“The most expensive yearling ever purchased in the southern hemisphere, a half-brother to Black Caviar, is euthanized at age 2 due to laminitis developed from an adverse reaction to systemic antibiotics.”

3. Anatomical Review
The weight of a horse is distributed down the bony column of the limb and is able to dissipate laterally across the hoof due to the laminae that suspend the distal phalanx within the hoof.

4. The epidermal laminae on the inside of the hoof wall project inward to interlock with the dermal laminae that are attached to the distal phalanx, thus suspending the distal phalanx within the hoof capsule.

5. Laminitis : inflammation of the laminae resulting in a failure of the inter-digitation between the dermal and epidermal laminae.
Depending on the site of laminae detachment, the distal phalanx can sink or rotate within the hoof, which could ultimately cause penetration of the sole.
Once the distal phalanx has rotated due to tension from the deep digital flexor tendon, laminitis is termed founder.

6. Three Stages of Laminitis
1) Developmental : horse is exposed to a predisposing factor of laminitis
2) Acute : horse exhibits clinical signs of laminitis but there is no radiographic evidence of distal phalanx displacement
3) Chronic : horse that has suffered from displacement of the distal phalanx and as a result is more susceptible to re-submission

7. Predisposing Factors / Causes
1) Bacterial Sepsis
black walnut toxicity (ingestion or direct contact in bedding)
carbohydrate overload (excessive grain intake)
retained placenta in broodmares
pleuropneumonia (secondary bacterial infection from pneumonia)
enterocolitis (inflammation of the colon and small intestine)

8. Predisposing Factors / Causes
2) Metabolic / Endocrine Disorders
equine cushing’s disease
equine metabolic syndrome
3) Excessive Concussion / Weight Bearing
complementary lameness

9. Example: Carbohydrate Overload
If a horse consumes an excessive amount of grain in a short period of time, rapid fermentation of the carbohydrates that have passed undigested through the small intestine results in a high level of lactic acid in the hindgut.
The high levels of lactic acid in the hindgut destroy bacteria resulting in endotoxins (a toxic substance in bacteria) in the bloodstream.

10. Endotoxins in the bloodstream trigger excessive production of Metalloproteinase (MMP).
In normal levels, MMP separates the laminae in small increments to allow hoof growth.
Carbohydrate Overload can also occur in “carbohydrate sensitive horses” from high sugar levels during rapid growth stages of pasture grasses.
Grass incurs rapid growth stages during spring and after rain fall following a drought.

11. Clinical Signs heat in the hooves bounding digital pulse
laminitic stance
reluctant movement

12. Diagnosis
Diagnosis in acute cases can be made from assessment of clinical signs such as a laminitic stance and a bounding digital pulse.
X-ray is the standard for accurate diagnosis of laminitis as well as determining the severity and progression of displacement of the distal phalanx.

13. Treatment
If the horse is at risk for laminitis due to an excessive consumption of carbohydrates, preventative treatment is recommended if available prior to the onset of clinical signs.
The intestinal tract can be cleared via a nasogastric tube of mineral oil by a veterinarian at 4 to 6 hour intervals. Mineral oil acts as a bulk laxative and coats the wall of the intestine, inhibiting absorption of toxins.

14. Acute Laminitis is a Medical Emergency!!!
Administer NSAID
(non-steroidal anti-inflammatory medication)
It is important that the manager is aggressive in administration of NSAIDs if the horse is exposed to a predisposing factor of laminitis until approximately 48 to 72 hours after the horse is not showing clinical signs or systemic inflammation / toxemia.
If the horse is at risk for laminitis due to carbohydrate overload or systemic illness, the standard NSAID is Flunixin Meglumine (Banamine) due to its efficiency against toxemia.

15. In horses with chronic laminitis, Phenylbutazone (Bute) can be administered long-term (up to 3 grams per day) for analgesic effect.
To avoid toxicity, administration of Bute should be stopped for at least 24 hours every 5 to 7 days of treatment. If the horse is too painful to be without an NSAID during the 24 hour break, administration of an alternate NSAID can be used.
Acepromazine, commonly used as a tranquilizer, can be administered to increase blood flow but is only effective for approximately one hour after administration.

16. Treatment of acute and chronic laminitis should also include an attempt to reduce the force of the horse’s weight on the feet.
In natural circumstances, the solar surface of the hoof provides support to the distal phalanx in barefoot horses as long as the horse is standing on a pliable surface.
In the barefoot horse, a hard surface decreases the support from the solar surface of the hoof.

17. In a shod horse standing on a firm surface, the support from the solar surface disappears due to the thickness of the shoe and the laminae bear the entire responsibility of suspending the distal phalanx.

18. The addition of putty to the solar surface in a shod horse has the same effect as a horse standing on a soft surface.
It is important to decrease mechanical force on the laminae brought on from exercise.
The horse should be put on stall rest with a soft, deep bedding. The standard choice of bedding is a 6 inch deep sand.

19. Prognosis
The prognosis is highly variable and dependent on the case duration, severity, number of affected feet, and underlying cause.

20. Please use the following password to access Quiz 7… Laminitis2015