Prolonged wet and hot weather produces conditions favourable to flystrike in livestock. Sheep in particular can be severely affected quickly.

Producers should lookout for wounds or sores that are infested with maggots. These wounds will often be noticeable because of a very strong smell or they are weeping liquid and staining surrounding wool. Common sites include the breech and around the pizzle of wethers and rams.

For small numbers of struck sheep, it may sometimes be possible to catch and treat individuals in the paddock. However, for larger numbers, yarding with crutching and/or chemical treatments may be best as soon as this can be accomplished.

Following floods or major rain events, the populations of biting insects usually increase significantly. These insects include buffalo fly, midges and mosquitoes, and may also include stable fly and other biting flies.

Animals are adversely affected by such insects in two ways:

• persistent biting causing distress (a welfare consideration) and the associated loss of production due to distress, excessive walking and failure to feed out properly
• transmission of diseases by insects (three-day sickness being the most common).

Several problems that arise in addressing the problem of insect worry include that:

• animals usually cannot be mustered for some time after floods or rain because it is not possible to get onto country or cattle will not work on boggy country, even if using ATVs or helicopters. This limits the options for treatment significantly
• there are limited chemicals registered for use on insects other than buffalo fly
• retreatment with the same or related chemicals at short intervals is prohibited due to the high risk of development of tissue residues and the possibility of toxicity issues.

Note: when using chemicals, always refer to the directions on the container. These directions give the species that can be treated, dose rates to use, retreatment intervals and withholding periods to observe before sale for slaughter.

How to treat insect worry

If stock can be mustered and handled through a race

• Pour-on preparations should work. A number of deltamethrin preparations are available with registrations for use that include buffalo fly, stable fly and for Culicoidies brevitarsus (one of the biting midges).
• Application of insecticidal ear tags should give relief from susceptible insects such as buffalo fly.
• If only buffalo fly control is needed, other pour-on preparations are available.

If stock can be mustered or confined in a small yard

• You can overspray cattle with suitable chemicals such as Fenvalerate or Chlorfenvinphos for buffalo fly. Note that there may be resistance problems with some chemicals, so you should seek advice from knowledgeable local suppliers on suitable chemicals. You can also use Fenvalerate on horses to prevent or treat Queensland itch caused by Culicoidies brevitarsus.

If stock can't be mustered but are frequently using watering points or cattle camps, or working specific areas

• You could erect back rubbers in places that cattle frequent. Chlorfenvinphos is registered for use in back rubbers.
• You could light and maintain smoky fires. Insects are repelled by smoke. It may be necessary to ensure stock feed out at least some time.

Flooding may drown ticks, but tick numbers and the risk of tick fever can increase with the associated wet and warm weather. This is particularly a problem if tick numbers have previously been low, as only a small proportion of the herd may have developed immunity to tick fever. It is recommended that you increase monitoring for ticks and tick fever, and take action as necessary.

Symptoms of tick fever

Tick fever is caused by 3 different organisms, all of which cause anaemia. Generally, there is severe disease with animals showing depression, weakness, jaundice, fever and staggering. Death can occur in less than 2 days.

Disease caused by Babesia organisms is usually associated with high fever (frequently over 40°C), and there may be red (blood-stained) urine. Fever is not a consistent finding in disease caused by Anaplasma organisms and the urine may be dark yellow to dark brown. Diagnosis is confirmed by examination of tail tip blood smears. If you see any of these symptoms, contact your veterinarian.

Control ticks and monitor stock

Returning displaced stock

Dip all stock before or after they return to the property and keep them under close observation (preferably daily) for at least 3 weeks, as they may be incubating babesiosis during this period. Anaplasmosis can incubate for up to 60 days, so frequent observation (at least twice each week) should continue after the initial intensive monitoring.

Dipping stock

Where properties still have charged dips, strategic dipping can be employed to knock down tick populations. Dips that have been affected by floodwater may require recharging to bring them to the correct strength. Where dips are no longer charged, pour-on or injectable preparations can be used to control ticks. In either case, pay attention to sale schedules and withholding periods, and select appropriate chemicals.

Immunity to tick fever

In unvaccinated herds, be particularly vigilant if tick numbers have been low over previous years, as animals may not have been sufficiently exposed to ticks to acquire immunity. Even with moderate numbers of ticks, it is possible that an animal hasn't been exposed to tick fever organisms.

Be sure to regularly monitor stock. If necessary, implement a vaccination program to provide stock with sufficient immunity. You can contact the Tick Fever Centre by phoning our Customer Service Centre to discuss vaccination issues and order vaccine.

Also consider...

• Learn more about managing tick fever in cattle and tick fever vaccines for cattle.

The moist conditions after floods favour the survival of worm eggs and larvae on pasture. Consequently, an increase in worm infestations may occur in the immediate post-flood period while animals are still under stress, and where they may be congregated for feeding or treatments.

Monitoring livestock

It is important that you monitor for signs of worm infestation. Signs include scours/diarrhoea, soiled tails or pale gums. Worm infestations can result in a failure to thrive and, in more serious cases, cause death.

Sheep in particular may fail to move about in the wet conditions, resulting in a considerable build-up of worms in a short period of time. Goats can also succumb rapidly to worm infestations and should be monitored closely.

With cattle, unless already weakened by other diseases, most adult stock will have sufficient immunity to resist infestation, but younger stock are more likely to become infested and show signs of disease and loss of production.

Diagnosis and treatment

If you suspect that worms are an issue, carry out a worm check test for confirmation. Collect about 30 grams (a heaped desert spoon) of fresh faeces in a sample bottle (or small clip seal bag) and chill (don't freeze). Submit this as soon as possible to a veterinary laboratory through your local veterinarian or Biosecurity Queensland officer. To give an indication of worm status, collect 10-20 fresh faecal samples from a mob. If worm infestation is diagnosed, treatment should be given as soon as possible as losses can occur within days.