Foot Rot or Scald?

It is winter, the ground has been wet for what seems like forever and you notice that a lot of sheep in your flock are limping. 

These wet conditions are the perfect breeding ground for scald, which usually appears before foot rot sets in.

When the skin between the toes is constantly wet, it can erode and provide the perfect opportunity for bugs to enter and start causing mischief by infecting the skin and deeper layers. 

The baddies: F. necrophorum and D. nodosus

• F. necrophorum is the bug found in scald. 

• With foot rot, F. necrophorum is joined by another bug, D nodusus, and working together, they attack the hoof which leads to the horn tissue separating.

• Of interest, D nodosus only lives on diseased feet and probably survives for no more than 14 days in feces, pasture and soil. However, it can live for years in the hoof of an animal.

• D nodosus is only found in the infected feet of ruminants. This is why trimmings from infected hoofs should not be left where other animals can stand on them and pick up the infection.

Be prepared!

As soon as you see signs of lameness, it is important to examine the sheep and see what is going on with their feet. You will need good foot shears and either a tetracycline antibiotic or similar spray developed specifically for foot rot. If possible, the feet should be cleaned with  warm water and a toothbrush or scrubbing brush so you can see exactly what is going on. Clean the feet gently as they will already be raw and sore, you don’t want to make things worse. 

Scald (Ovine Interdigital Dermatitis)

Once you’ve cleaned off the mud you may find that the skin between the toes is red, swollen and hot with moist skin and some necrosis (rotting). There may also be lesions present. These signs indicate a mild case of foot scald. If the sheep are carrying their feet (not weight bearing) then the condition is more advanced and has got into the deeper layers of the skin. Mild or more severe, you need to treat the infection.

Scald

Foot rot

If, when you examine the hoof there is evidence of the horn having separated from the soft tissues of the foot, especially at the heel, the animal may have foot rot. There is also a distinct smell with foot rot which is literally like something rotting. This is thanks to the smelly discharge created by the bacteria which cause the disease. 

Foot rot loves moisture and warmer temperatures. Generally it likes temperatures above 10 degrees C, so may not be such a problem during winter in colder parts of New Zealand. 

In more temperate climes it can flourish. 

If there is separation from the hoof on the outside of the hoof wall, no heat in the hoof and no smell you may be dealing with shelly hoof which is not infectious and just needs to be trimmed to stop dirt and mud from getting impacted.

Foot rot

Treatment

Scald

Start by cleaning the feet and spray between the claws with the antibiotic spray. Depending on how badly the animals are affected, this may be enough to clear the problem. If there is any dry ground available, get them onto it. Of course if it is a wet winter this may not be possible, so the next step is to treat them with a weekly or fortnightly foot bath.

Foot rot

Trimming a hoof that has foot rot can make it worse so conservative paring with your hoof trimmers is important. If there isn’t too much overgrowth or separated horn, the feet can be left, however if there is separation or loose horn, it’s better to trim it. Little is best! Once the feet have been carefully pared apply antibiotic spray.  Usually a vet will administer an antibiotic injection too.

Footbath 101

Footbaths usually consist of a long narrow trough, either concrete or plastic, that will hold a number of sheep at a time so their feet can be soaked in a solution. The bath needs to be in a race, so that the animals are contained and can’t step out of it. The length of the bath or trough will determine the number of animals you are able to treat at one time.

You can also get a ‘hoofmat’ which you put into the footbath solution and the animals stand on the solution-soaked mat. This helps to open their claws and also prevents splashing.

For smaller flocks or single animals you can set up a footbath in a bucket, feedbin or even a small plastic container if you’re just treating one hoof.

What goes in the footbath? 

A solution of Zinc sulphate or formalin are the most common products used for sheep. Copper sulphate can be used for cattle.  Formalin may now only be purchased if the purchaser holds a Handler’s Certificate which is obtained through WorkSafe.  

Zinc sulphate can be bought in a powdered form in bags from your local stock agent. Formalin comes in a liquid. The Zinc or formalin is diluted and the bath filled to about two inches of solution - enough to cover the coronet band.

Standing the sheep in a 10% solution of Zinc sulphate or 5% Formalin will kill bugs and dry out the skin. The sheep should then stand in a dry area for at least one hour afterwards to allow the feet to dry. If you have a grating floor that is ideal, otherwise a concrete or other dry floor. 

Foot scald may take some time to resolve if conditions stay wet but as soon as the ground starts to dry out, you should notice a marked improvement.

How often and how long to footbath?

If you’re dealing with an active infection then at least 20-30 minutes daily for 3-5 days. 

If you’re using the footbath as a preventative measure, then 15-20 minutes every few weeks is enough.

Getting it right

• Mud or dirt in the solution will make it inactive so walk the sheep through a water bath or hose the hooves to remove organic matter.

• Allow the feet to dry on a clean surface and if there is an active infection consider using foot rot spray for added protection.

• Always use a fresh solution in the footbath or you’ll be spreading infection, not preventing it.

• If possible move the animals to dry ground or to an area where no infected animal has been for at least a couple of weeks.

Other treatments

There is a vaccination for foot rot available, which is given four-to-six weeks apart. For sheep that don’t have foot rot, they will be protected and for those animals that do have it, they will heal more quickly and the severity of the disease will be diminished. The vaccination only lasts four-to-six months.

As mentioned, antibiotics can also be injected for sheep with foot rot. A single high dose of penicillin-streptomycin has been shown to have a good effect. For it to work, sheep should stay on a dry area for at least 24 hours after the injection. 

What species of animals are affected by scald and foot rot?

Sheep, goats, deer and cattle can all be affected by scald and foot rot. The foot rot bug affecting cattle does not transmit to sheep, but infected goats and sheep can infect each other. 

Foot rot and scald can have a major impact on the production, health, and well being of affected animals, so it is important to get on top of the problem as quickly as possible. 

For more great information on looking after livestock check out our courses.