Animal Welfare

Standard Operating Procedures - sheep
Dipping

Ref Code: SHE07

Objective

To control external parasites, either by wet dipping through a plunge or shower dip or by backline treatment.

Alternatives to animal use for teaching

Video

Details of procedure

Only chemicals registered for use on sheep in dips may be used. For demonstrations, consideration should be given to omitting the chemical from the dip

1. Plunge Dips

Plunge dips are labour intensive and expensive due to higher wastage of chemical at the end of dipping, and due to losses caused by deaths and greater spread of diseases such as mycotic dermatitis and cheesy gland. Sheep previously plunge-dipped may become reluctant to enter and each may have to be forcibly pushed in. The system is too rough to use with sheep heavy in lamb and different sized sheep should be drafted off and dipped separately.

Deaths can occur by drowning, by inhalation or by ingestion, while infection can occur through shearing cuts, dog bites, sharp projections in the yard or at the entry to the dip, or by grass seeds that puncture the skin. Mycotic dermatitis can be spread through the dip, particularly if sheep are held closely-packed in the draining pens.

The sheep should be yarded overnight with access to water but not to feed, so they empty out. This reduces contamination. Forcing and draining pens should be cleaned regularly to reduce the amount of organic matter carried into the dip, and the race leading to the dip entry should be of rough concrete to remove dirt from the feet.

Draining times should be kept short to reduce contamination of the dip, and to allow more sheep to be dipped before contamination is excessive and the dip has to be dipped out and cleaned.

Hot, tired sheep should be rested prior to dipping, as skin absorption of chemical and drinking of dip wash can result in losses due to poisoning.

When using a plunge dip, particular attention should be paid to the following points:

Sheep should be dipped as soon as shearing cuts have healed, preferably within 2-4 weeks and never later than 6 weeks after shearing.
The volume of the dip should be carefully calculated, but as this is often difficult, it may be better to add water from a 500L container or use a water meter.
A dip stick should be calibrated by marking each 200-500L as it is added.
When using chemical, the dip should be charged at the correct rate according to the label directions. A premix should be made and poured along the length of the dip. The dip concentration must be maintained by topping up according to the label directions. Topping up should usually be done when the volume drops by no more than 25% of the initial volume.
The dip must be thoroughly stirred using a paddle or broom.
The head of each sheep should be pushed under twice with a downward and backward movement to open the fleece. Remember that the back of the neck is the hardest part to wet in plunge dipping.
Sheep can be checked for wetting by using a water-soluble copying pencil or a scourable dye in the dip wash.
The dip should not be allowed to become excessively dirty, or skin infections and wool staining may occur. To avoid this, the dip should be dipped out, when one sheep has been dipped for every 2L of the dip's working volume. When dipping out add chemical as directed on the label to maintain the concentration in the dip. Hibitane can be added to help prevent the build-up of bacteria in the dip.

2. Shower Dips

The sheep should be yarded overnight with access to water but not to feed, so that they empty out and the contamination of the dip is kept to a minimum. Forcing and draining pens should be cleaned regularly during dipping to reduce contamination of the dip.

The time taken to wet the sheep thoroughly depends on length of wool, body size, breed and the efficiency of the shower. Various combinations of time for top and bottom sprays are used, but the top sprays are the ones that wet the sheep and should be used at least 75% of the total spray time.

If a shower dip is used, the manufacturer's recommendations must be followed. In particular, attention should be paid to the following points:

When using chemical, constant replenishment is recommended to minimise wastage and to ensure that all sheep receive sufficient chemical to kill all lice.
Charge the sump and replenishment tank according to the label directions.
Run the top sprays for 3 minutes in an empty dip to ensure adequate mixing of the chemical before dipping, immediately after topping up, and if standing for more than 1 hour.
Do not overload the dip. The sheep should be able to move freely.
Sheep should be dipped within 2-4 weeks of shearing whenever possible, and never later than 6 weeks.
Ensure that the top arm is rotating at the correct speed (8-12 revolutions per minute), and the dip wash covers the dip evenly and is thrown up the sides of the dip above the height of the sheep's heads.
Sheep can be checked for wetting using either a water-soluble copying pencil or scourable dyes in the dip wash.

3. Backline Treatment

Points to note when using a backline treatment:

Sheep must be treated within 24 hours of shearing. Sheep must be cleanly shorn. Severe cotting from Dermatophilus infection (dermo, mycotic dermatitis), matted wool from lice or blowfly infection or unshorn areas in neck folds make it unlikely that backline treatment will achieve eradication.
Ewes should not be treated within 8 weeks of lambing. Ewes with lambs at foot should also not be given backline treatment.
Weigh the heaviest sheep in each mob and set the gun to deliver the dose for that sheep. Check that the gun delivers the correct dose.
The chemical must be applied according to label directions.

Drugs, chemicals or biological agents

All chemicals must be registered and the instructions on the label, including withholding periods and safety precautions for humans, adhered to. The person in charge of any demonstration is responsible for Occupational Health and Safety issues.

Impact of procedure on the wellbeing of animal(s)

Provided sheep are handled with care, there is little impact on animals.

Reuse and repeated use

Only one demonstration per animal.

Care of the animal(s) during/after the procedure

Keep sheep in draining pens until dripping has almost ceased, then allow them to dry in a sunny situation. Animals should be let out of the yards to dry as soon as possible - do not hold wet sheep in yards or sheds any longer than necessary.

Pain relief measures

Nil

Qualifications, experience or training necessary to perform this procedure

Experience in sheep handling and dipping procedures.