Controlling tick fever outbreaks in cattle

Tick fever outbreaks can be costly and you will need to act quickly to control the disease. If you suspect tick fever, contact your veterinarian for expert assistance. The following tips will help minimise losses.

Steps to control tick fever outbreaks

1. Confirm diagnosis

A fast and accurate diagnosis is vital for treating animals and managing the outbreak. Consult your local veterinarian, a government field veterinarian or staff at Biosecurity Queensland's Tick Fever Centre.

In most cases, a diagnosis can be made by examination of blood smears under the microscope. Wherever possible, these samples should be taken prior to treatment or, in the case of dead animals, as soon as possible after death. The samples should be sent to a diagnostic laboratory for examination.

2. Treat sick cattle

Treat sick cattle with a suitable drug as soon as possible and identify those that have been treated. If treatment is delayed, sick animals may not recover.

If the organism responsible for the outbreak has been determined, use the following treatments:

If you are unsure which tick fever parasite is causing the problem, use either imidocarb (Imidox®) at the high dose rate of 2.5mL/100kg or imidocarb at a lower dose rate of 1mL/100kg in combination with oxytetracycline.

The imidocarb withholding period for meat is 28 days.

Note: imidocarb is not registered for use in lactating dairy cattle. However, an Australian Pesticides and Veterinary Medicines Authority 'minor use' permit does allow its use in Queensland and New South Wales. There is a 14-day milk withholding period when lactating dairy cows are treated once at a dose rate of 1mL/100kg.

Oxytetracycline is marketed under a number of trade names with differing withholding periods. Restrictions apply to the supply of oxytetracylines – consult your veterinarian. Your veterinarian can also advise you regarding supportive treatment for very sick animals.

Observe the manufacturer's instructions when using any drug treatments. Reduce tissue damage when using large volumes of these drugs by injecting in multiple sites.

3. Remove ticks

Use a tickicide (acaricide) to remove ticks from all animals. This helps prevent a secondary outbreak caused by future generations of ticks. Contact your local biosecurity officer for advice on suitable tickicides and the best tick control strategies in your area.

If possible, transfer the mob to a new paddock where you can closely monitor them.

4. Assess the severity

Assess the severity of the outbreak and risk of further cases. In consultation with your veterinarian or Tick Fever Centre staff, decide whether to treat the entire mob (refer to step 2 above on how to treat sick cattle), or monitor cattle closely and treat individuals as clinical signs develop.

New cases can occur for up to 3 weeks after the initial cases.

5. Vaccinate all 'at-risk' animals

Vaccinate all 'at-risk' animals in the affected mob with tick fever vaccine, except those treated with imidocarb or showing clinical signs of tick fever.

There are 2 options:

Option 1

Wait 1 to 2 weeks for the outbreak to abate. Treat any sick animals during this time, then vaccinate all animals that have not been treated, and monitor for incubating cases and possible reactions to the vaccine. Do not vaccinate animals treated with imidocarb for at least 8 weeks after treatment, as the treatment may interfere with development of immunity. Apply tick treatments to reduce tick burdens on the cattle.

Option 2

Vaccinate as soon as possible, and then monitor for both natural cases of tick fever and possible reactions to the vaccine. Overall, you will spend less time monitoring the mob as field cases of tick fever will usually show up before or during vaccine reaction periods. You will need to revaccinate any animals that required treatment with imidocarb (see option 1).

It takes about 3 to 4 weeks for immunity to develop to the 2 Babesia parasites, and up to 2 months to develop to Anaplasma marginale.

6. Monitor cattle in adjoining paddocks

Monitor cattle in adjoining paddocks, collect samples from any suspect cases and treat if necessary.

7. Protect the rest of the herd

Protect the rest of the herd by developing a dipping and vaccination strategy, starting with groups that are most at risk.

8. Start a long-term risk management strategy

This should include annual vaccination of all calves 3 to 9 months of age, and vaccination of all introduced cattle, plus appropriate tick control strategies.

Also consider...

• Learn more about vaccinating cattle for tick fever.