Once the acute phase has passes, if a normal pattern of hoof growth has not re-established i.e. slightly faster growth at the toe compared to the heels (see Hoof growth). As the hoof continues to grow in a distorted way, the old undistorted hoof will have grown down, to be replaced by a continuously distorted hoof. This will have the characteristic diverging growth rings, which have long been associated with chronic laminitis.

The intense lameness seen in acute laminitis is replaced by a lower level of pain, partly caused by the differential in hoof growth and partly by the lost integrity of the hoof’s shape. The prominent ‘dropped sole’, often seen in chronic laminitis can be reinterpreted as a lifted dorsal wall leaving the sole and distal phalanx vulnerable to pressure from the ground (Fig. 1).

All chronic laminitic feet are characteristically boxy, this leaves them more vulnerable to the effects of rapid heel growth, which due to the straight-sided nature of the hoof will focus all hoof distortion into the dorsal wall area. Constant rasping of the dorsal hoof wall will be necessary to maintain the appearance of a normal hoof shape, this process may reduce pain, as the thinned dorsal wall will exert a weaker lifting force onto the underlying laminae.

The long term prospects for chronic laminitic equines is very poor, gradually the lameness becomes more severe as many internal changes take place within the foot, changes in the shape and demineralisation of the distal phalanx being the main factors. Life expectancy for chronic laminitic cases is difficult to predict but five years is typical in many cases.