Texas A&M University

Case and Control Definitions

Please refer to the important definitions we have selected for the laminitis case (affected horse) and the 2 control populations (healthy control and lameness control). Criteria for inclusion and exclusion are strictly defined and must be followed. Please contact us if you have questions regarding these definitions.


Laminitis Case

Case Definition:

  • The first recognized case of laminitis in the horse that has developed within 4 weeks of examination.

Please note that these cases may have a history of pasture exposure, confirmed or suspected endocrinopathy, recent corticosteroid administration, or may be idiopathic in nature.

  • Evidence of bilateral forelimb lameness of Obel Grade 2 or higher in severity, and at least 2 of the following findings:
    • sensitivity of hoof testers that is greatest at the region of the toe at the time of initial examination
    • a characteristic foundered stance
    • radiographic evidence of laminar thickening; or,
    • gross or microscopic evidence of laminitis

Exclusion Criteria:

  • Previous history of laminitis
  • Laminitis associated with sepsis (e.g. strangulating intestinal lesion, metritis, etc)
  • Laminitis associated with non-weight bearing lameness
  • Laminitis associated with excessive grain consumption
  • Other concurrent disease conditions of the foot such as sole abscesses
  • History of navicular disease/navicular syndrome
  • An equid other than a horse or pony, and,
  • Radiographic signs of chronic laminitis such as rotation or remodeling of the third phalanx

Healthy Control

Case Definition:

  • An apparently healthy horse residing at a different premise than the one at which the index case of laminitis was observed.
  • The next horse examined by the veterinarian for a normal wellness examination, vaccination, Coggins testing, dental, or health certificate.

Exclusion Criteria:

  • History of laminitis or clinical or diagnostic findings indicating previous laminitis (e.g., divergent hoof rings, dorsal hoof dishing, pre-existing radiographic findings consistent with laminitis such as rotation or the 3rd phalanx)

Lameness Control

Case Definition:

  • A horse lame in 1 forelimb only residing at a different premise than the one at which the index case of laminitis was observed.
  • Lameness must be no more than 4 weeks in duration since the onset of signs and be assigned a score of greater than or equal to 3/5 according to the AAEP scale.
  • Horses with pars pituitary intermedia dysfunction (PPID) or equine metabolic syndrome may be included as a lameness control.

Exclusion Criteria:

  • History of laminitis, bilateral forelimb lameness, or radiographic evidence of laminitis.