Treating sheep with footrot

There are two steps in footrot management:

1. Footrot control
2. Footrot eradication

Footrot control

Control treatments reduce the severity of infection and minimise the number of sheep contracting footrot which in turn increases the success, economics and ease of eradication procedures.

The affected sheep will need to walk through or stand in footbath for 5 to 10 minutes.

Control treatments are a choice of:

• course of two vaccinations
• footbathing in zinc sulphate or formalin every 7 to 10 days
• footbathing in 'Radicate' every 12 to 16 days
• combination of vaccination and footbathing.

For control periods of less than 8 weeks, footbathing is the best choice. For short-term footbathing zinc sulphate or formalin should be considered as it requires less capital investment.

If unweaned lambs are to be involved, vaccination is easier and causes fewer mis-mothering problems than footbathing.

Vaccines will not provide any significant benefit until after the second dose. It is therefore necessary to footbath sheep for 4 to 6 weeks until after the second dose is given. To maintain protection beyond 10 to 12 weeks a single booster dose is required, and should be repeated every 10 to 12 weeks while protection is necessary.

Treatment chemicals

• Zinc sulphate 10% – 1kg to 9 litres of water (safer and gentler on sheep)
• Formalin 5% – 1 part formalin to 19 parts water
• Radicate – 10 litre container mixed with 100 litres of water

Radicate  provides two weeks protection.

Specific treatment instructions include:

1. Paring
2. 15 minute footbath (within 4 hours of paring)
3. 15 minutes on slats, grating or a dry concrete
4. 1 hour on a clean dry area

Vaccine:

• 1ml dose, 2 doses, minimum 6 weeks apart and booster every 10 to 12 weeks while spread conditions persist.

Provides good protection of clean sheep rather than cure.

Antibiotic injection:

• several, as prescribed by a vet

Provides good cure but no ongoing protection against reinfection.

Footrot eradication

To eradicate footrot from a property all the D. nodosus bacteria must be killed or the infected sheep removed. As the bacteria cannot be seen you must look for the signs of their presence, cull those sheep with signs and use chemicals and time to kill any bacteria on the remaining sheep and pasture.

First consider all the options and costs before deciding on an eradication procedure. A properly planned program is essential for successful eradication of footrot.

Before choosing a program that will best suit your property and situation, answer these questions to help guide you to the best choice:

1. How many mobs are affected?
2. Can I operate the farm and still keep the infected and clean sheep separate?
3. How old are the sheep in the infected mob?
4. What is the slaughter value of these sheep now?
5. What will their value be after shearing and weaning?
6. What is the replacement price for these sheep?
7. How much will these sheep produce from now until culled for age?
8. What is the cost of control and eradication?
9. What are the costs of each of the options available?

Table 1: Choices of eradication

Immediate slaughter at an abattoir

Slaughter can be the best option when infected sheep are aged, or in prime condition with a high slaughter value compared to replacement store prices or when a few infected sheep or small mobs are putting the majority of the flock at risk. Disposal of these must be direct to an abattoir as a paddock, CALM or 'over the hooks' sale.

Control, then slaughter after shearing and weaning

After removing the current year's production of wool and lambs, the economics of slaughter are often very sound and attractive compared to treating, as long as you can prevent the infection spreading to clean mobs. Control measures must of course prevent suffering, loss of production and loss of body condition.

Control then summer eradication

Step 1 – Control

A summer eradication program can achieve good results if the spread and severity of footrot is restricted during spring. A planned control program needs to be implemented as soon as footrot is diagnosed. Vaccination and footbathing are both useful options. They each need to be costed and labour requirements considered.

Step 2 – Eradication

Once pasture has dried off in summer, all sheep must be tipped up and individually examined, foot by foot, paring sufficiently to ensure an accurate diagnosis.

Examination:

• permanently brand all infected or suspect sheep
• sort sheep into clean and infected mobs.

Culling all infected sheep will give better results. An infected mob kept for treatment is a high risk for breaking down and infecting clean mobs.

Infected sheep to be retained for treatment require paring, sufficient to return feet to normal shape and size and to expose all pockets of infection. If infected sheep are to be culled, paring can cease as soon as a diagnosis is made.

Footbath:

• clean mob then release them into a clean paddock, one that has not had sheep in for the previous 7 days.

In dry environments foot bathing may not be necessary.

Infected mob either:

• footbath and move to a clean paddock
• inject with antibiotics and move to a clean paddock.

Examine again:

• clean mob – every sheep in this mob must be examined again in 3 to 6 weeks
• repeat examination and bathing cycle until 2 consecutive clean inspections are achieved.

Infected mob:

• after 4 weeks inspect all feet.

Any sheep not cured should be culled immediately for slaughter.

Repeat treatment and examinations until 2 clean inspection are achieved. The infected  mob becomes the cured mob.

Surveillance and isolation:

• keep clean and cured mobs separated and isolated until after next spring
• keep sheep under close surveillance for signs of lameness – any lameness must be checked to determine the cause.

If footrot is detected restart the program.

Making foot inspection easier and more effective

Sheep handlers

A variety of handlers are available from the V-belt multiple sheep machine, to single sheep unpowered handlers and even a bag sling or cradle. They are good at relieving back strain and fatigue and therefore improve the quality and speed of operation.

Pneumatic shears

These are a great asset for paring feet, particularly in summer.

Footrot contractors

Contractors are available to do the whole job, to supply a sheep handler and shears or just labour. They can be a very effective and quick means of getting the job done, but make sure they are doing the job to your satisfaction.