Stock problems after a flood


Users of agricultural (or veterinary) chemical products must always read the label and any Permit before using the product, and strictly comply with the directions on the label and the conditions of any Permit. Users are not absolved from compliance with the directions on the label or the conditions of the Permit by reason of any statement made or not made in this publication.


  • Are your stock getting enough hay or grain in their ration to provide energy for late pregnancy or lactation?
  • Are stock suffering from cold stress?
  • Is there enough roughage to discourage stock from eating weeds that may be harmful?
  • Have you removed baling twine from food drop zones, to prevent stock injury and wool contamination? (Refer to Cleaning up fodder drop zones after a flood.)


  • Have other stock been boxed with yours? They may have footrot or lice.
  • Is your boundary secure?


When a flood occurs, blowfly strike in sheep will be a greater or lesser problem depending on shearing date, blood line (susceptibility) and whether the flood has occurred in cooler or warmer months.

When susceptible sheep are saturated to the skin by heavy rain or floodwaters, resultant fleece rot or dermo will attract blowflies if the weather stays warm.

If farmers are able to quickly get to sheep after floodwaters recede and before flies become active, use of a product based on cyromazine, dicyclanil or ivermectin could be used to give long-term protection (i.e > 11 weeks, depending on the active ingredient chosen).

If sheep have already been struck, either hand jetting or hand dressing of individual struck sheep will be necessary. Ivermectin-based products can be used for both applications. As well as providing up to 12 weeks flystrike protection if sheep are jetted thoroughly, if used as a dressing, ivermectin has been shown to be effective against organophosphate resistant maggots. Producers should always follow instructions on the label when using chemicals.

For further information see:


Consider shearing as soon as possible. Tender and water-damaged wools incur discounts. If you are shearing early, consider the long-term implications of a new shearing time in your future farm management.


After heavy rain or flooding, worms can be a significant problem. Don't guess - WormTest! (worm egg count). For more information on sheep worm control, see Internal parasites.

Pulpy kidney

There is a risk for unvaccinated lambs and weaners grazing lush pasture growth following the receding floodwaters.

Vaccination with 6-in-1 against pulpy kidney and other clostridial diseases is very effective and should be carried out as soon as it is practical to do so.


Likewise, bloat will appear if the weather stays warm. The most dangerous pastures are clovers and lucerne.


Watch for prolific growth of weeds, especially any unusual plants.


Heartworm will be spreading among your dogs due to mosquito build-up. Your local veterinarian can provide advice on methods of prevention.

Further information

Further information on the above topics and general advice on post-flood management is available from your nearest Local Land Services office.