Sheep are subject to a range of foot diseases that all cause lameness. These are especially common in wet weather when foot damage and skin inflammation pre-dispose sheep to developing infections.
FOOTROT (INCLUDING SCALD)
Footrot is a highly contagious infectious disease. Virulent strains of footrot cause severe lesions and spread rapidly in warmer, moist environmental conditions.
Often affects more than one foot.
In mild cases, (known as scald), some reddening between the toes.
In more severe cases, underrunning (i.e. separation) of horn from hoof. Starts at the inner wall, then progresses to sole, and eventually outer wall.
Infected feet often smell.
Infected feet may become flyblown.
The bacteria that cause footrot are Dichelobacter nodosus and Fusibacterium necrophrum.
Unless there has been a previous footrot outbreak in your stock, the most likely way of introducing the bacteria to your property is by the introduction of new stock that are infected.
The bacteria that causes footrot can live in the feet of a carrier sheep (or goat) indefinitely, even under dry conditions.
A paddock which has had no sheep, goats or cattle in it for seven days is likely to be free from footrot.
Control, Treatment and eradication
Control of spread involves footbathing (for long or short term actions).
Footbathing in 10% zinc sulphate helps treat existing lesions and reduce the spread of bacteria, improves the health, welfare and production of sheep, enhances the effect of a footrot vaccination program if used and provides precautionary quarantine treatment for introduced sheep.
Eradication programs involve the identification and removal of all infected sheep from a flock when footrot is not spreading.
All feet on all sheep must be inspected, and infected sheep or those requiring extensive foot trimming should be culled.
In some cases salvage treatment with foot paring, footbathing and antibiotic treatment can be used.
Repeat inspection is made four weeks after the initial inspection and continued with regular surveillance.
Lameness and obvious acute pain.
Swelling, usually just above the hoof.
In some cases, pus can be seen above the hoof or between the toes.
Usually only one foot affected, and only in a small number in a flock.
Damaged foot tissue due to physical damage or irritation.
Wet paddock conditions.
Feet trimmed too close to blood supply.
Failure to maintain sheep's feet in good condition.
Heavy sheep are more prone.
Pare or trim the feet, clean the infected area and apply an anti-bacterial compound.
Antibiotic injections and keeping the sheep on a dry surface will assist healing.
Applying zinc sulphate and bandaging may help.
Many cases take a prolonged period to heal and often the foot is permanently deformed.
Ensure the sheep's feet are kept in good condition by regular inspection and paring where necessary.
Prevent sheep from getting too heavy. Pre-lamb shearing has helped in some cases.