Sheep vary in their suceptibility to 'bad feet', both within and between breeds.

Footrot
Foot rot is caused by a bacterial infection picked up from the soil. It is more frequent in wet, puggy, conditions. Unsuprisingly, it is less frequent in summer. In bad cases, the infection spreads well up under the horn, and becomes foul smelling. Often the area where the hoof joins the leg is hot. The animal limps, and may kneel to feed.

The 'cure' is to keep hooves trimmed of excess growth so that mud and faeces don't get stuck under the 'toenail' (hoof). The animal has to be stood in a copper sulphate or zinc sulphate footbath for at least ten minutes. Some people mix zinc sulphate with a carrier such as milk powder and 'pack' a moist paste into the infected area.

The best cure is to keep sheep which have hard, slow growing hooves. Some individuals never ever get footrot.

Scald
Also caused by an infectious organism, this often simply a low grade case of footrot. The animal limps and may have hot areas around the top of the hoof. Treat as for footrot. Buy resistant animals.

Lameness
Lameness is often caused by a painful swelling of the lamina of the hoof (laminitis). This may be at least partly dietary in origin. Suceptibility has a genetic component (inherent hardness or softness of the hoof and inherent speed of hoof growth), and an environmental component (how wet or dry the paddocks are, for how long, and at what time of year).

Even animals that are not affected by footrot may become lame, especially in lush spring and autumn conditions. Hoofs grow out over a 4 to 6 month interval, so problems tend to come and go, depending on an interplay of conditions helping or hindering hoof hardness and health.

When the grass is very lush in spring and autumn conditions in the sheep's rumen can become very acid (acidosis). This reduces the B group vitamins - including biotin - manufactured in the sheeps gut by the normal intestinal and rumen flora. Less than optimal biotin may lead to softer hooves and suceptibility to lameness, because biotin is essential for hoof health and hardness.

Lameness usually self resolves after a few days. If not, look for injuries or signs of footrot.

Pregnant ewes heavy with lambs in autumn are often worst affected, as extra weight bears down on tender inflammed feet.


Hoof overgrowth

Some breeds, such as Shetland/Arapawa, had hard, slow growing hooves. Others, such as dorper, tend to have very fast growing hooves. Nail growth is highly heritable - if the ram has fast growing hooves, the progeny are likely to as well. Even when a ram with fast growing hooves is crossed with a ewe with hard slow growing hooves, the progeny may be as bad - or worse - than the sire.