Tendency to lie down whenever possible, and recumbency in extreme cases
Change in the outward appearance of the hoof in cases of chronic laminitis: dished (concave) dorsal hoof wall, "founder rings" (growth rings that are wider at the heel than the toe), a sole that is either flat or convex just dorsal to the apex of the frog which indicates P3 has displaced or penetrated, widening of the white line at the toe with or without bruising, "clubbing" of the foot. Change in the appearance of the coronary band: hair that does not lie in a normal position (not against the hoof wall), indentation or rim just above the hoof capsule allowing palpation behind the coronary band. In cases of sinking, it may be possible to palpate a groove between the coronary band and the skin of the pastern. Lameness evaluation
Hoof testingLaminitic horses are generally sore to pressure from hoof testers applied over the toe area. However, there is risk of a false negative if the horse naturally has a thick sole, or if the hoof capsule is about to slough. Obel grading systemThe severity of lameness is qualified using the Obel grading system:
Obel grade 1: Horse shifts weight between affected feet or continuously lifts feet up. It is sound at the walk but displays a shortened stride at the trot. Obel grade 2: Horse displays a stilted, stiff gait, although is willing to walk. It is possible to easily lift a front foot and have the horse take all of its weight on the contralateral limb.
Coly-Mycin has a recommended dose of 2.5 to 5 mg/kg colistin base a day, which is equivalent to 6 to 12 mg/kg colistimethate sodium per day. For a 60 kg man, therefore, the recommended dose for Colomycin is 240 to 480 mg of colistimethate sodium, yet the recommended dose for Coly-Mycin is 360 to 720 mg of colistimethate sodium. Likewise, the recommended "maximum" dose for each preparation is different (480 mg for Colomycin and 720 mg for Coly-Mycin). Each country has different generic preparations of colistin, and the recommended dose depends on the manufacturer. This complete absence of any regulation or standardisation of dose makes intravenous colistin dosing difficult for the physician.Colistin has been used in combination with rifampicin; evidence of in vitro synergy exists, and the combination has been used successfully in patients. There is also in vitro evidence of synergy for colistimethate sodium used in combination with other antipseudomonal antibiotics.Colistimethate sodium aerosol (Promixin; Colomycin Injection) is used to treat pulmonary infections, especially in cystic fibrosis. In the UK, the recommended adult dose is 1–2 million units (80–160 mg) nebulised colistimethate twice daily. Nebulized colistin has also been used to decrease severe exacerbations in patients with chronic obstructive pulmonary disease and infection with Pseudomonas aeruginosa. Resistance
Resistance to colistin is rare, but has been described. As of 2017, no agreement exists about how to define colistin resistance.