Ticks and livestock

What is tick paralysis

Tick infestation in livestock can lead to loss of condition and sometimes death. There are three main ticks of concern in NSW: paralysis tick, bush tick, and cattle tick.

Paralysis ticks (Ixodes holocyclus) are a common cause of sickness and death in cattle, alpacas, sheep and goats. They are native to Australia and primarily parasitise marsupials such as bandicoots, wallabies, echidnas and possums, which are usually immune to the tick’s toxin. Livestock, however, are vulnerable and may suffer ascending paralysis, recumbency, breathing difficulty and death if untreated.

Paralysis ticks are three-host ticks, meaning they attach to a host, feed, drop off and moult three times during their lifecycle. The stages are:

• Larvae (pinhead size)
• Nymph (matchhead size)
• Adult (pea-size)

Ticks spend more time on the ground than on the host and can survive off-host for 6–8 months if conditions are mild (not hotter than 32°C or colder than 7°C).

All stages can inject neurotoxins, but adults inject the most. Young animals are especially susceptible due to low body weight and lack of prior exposure. Experiments show that just two adult ticks can paralyse a 2–3-week-old calf.

Bush ticks (Haemaphysalis longicornis) are also three-host ticks. They spend most of their life in the paddock and only 5–7 days on the host. Cattle are the preferred host, but bush ticks also infest sheep, pigs, dogs, horses, humans and wildlife. They can transmit Theileria, a parasite that destroys red blood cells.

Cattle ticks (Rhipicephalus australis, formerly Boophilus microplus) are single-host ticks. Once larvae attach, they remain on the same animal through all life stages for about 21 days. Infestation typically occurs in Queensland, the Northern Territory and Western Australia. Cattle ticks can carry cattle tick fever and are identifiable by their pale leg colour.

When to watch for it

Spring is a common time for tick issues, as tick life stages emerge from dormancy in late winter and seek hosts. Tick paralysis cases peak from very early spring through mid-summer.

Tick numbers tend to be higher following years of high rainfall and thick ground cover, which protect the free-living stages. Wildlife presence also increases risk.

Young animals are most vulnerable, especially calves as young as four days old. Paralysis ticks are a year-round issue, but risk is highest in late winter and spring.

Clinical signs

Signs of tick paralysis may appear 3–5 days after attachment of an adult female tick. Without treatment, death can occur within 1–5 days.

Early signs include:

• Hind limb weakness
• Ascending paralysis (progressing forward)
• Recumbency
• Increased respiratory effort (grunting)
• Difficulty swallowing
• Inability to maintain a sitting position
• Lying on side, unable to lift head

Advanced signs:

• Respiratory failure
• Aspiration of gut contents
• Pneumonia
• Death from environmental exposure (heat, dehydration)
• Predation risk

Ticks may be hard to find and often hide in areas such as:

• Between hooves
• Nostrils
• Anus
• Vagina
• Inside ear canals
• Under fleece

Careful searching may reveal a tick crater after the tick has dropped off.

How to manage

Tick infestations should be investigated, especially if stock deaths occur. Identifying the tick species is important for appropriate management. The Tickboss website is a useful resource for tick identification.

Control strategies include:

• Altering breeding patterns to avoid birthing during peak tick season.
• Infusing Bos indicus breeds to increase tick resistance.
• Creating low-risk pastures by hard grazing or slashing bushy areas.
• Avoiding heavily vegetated paddocks for birthing.

How to treat

• Remove paralysis ticks manually.
• Use Amitrax (registered for paralysis and bush ticks) — effective for treatment but not as a preventative in extensive systems.
• Administer paralysis tick anti-serum via a veterinarian to neutralise unbound toxin.
• Early treatment improves prognosis; advanced cases may have a guarded outcome.
• Place treated animals in shade and nurse them until recovery.
• Do not leave paralysed livestock untreated in paddocks.

How to prevent

Prevention is challenging due to the tick’s short attachment period and environmental abundance.

• Use registered chemical treatments (sprays, pour-ons, washes).
• Synthetic pyrethroid insecticidal ear tags (previously registered for 42-day protection) are currently unavailable.
• Products registered for bush ticks may help prevent paralysis ticks.
• Always follow chemical labels and observe withholding periods (WHP) and export slaughter intervals (ESI).
• Do not use unregistered chemicals on food-producing animals.

Additional strategies:

• Manage susceptible animals with tick preventatives.
• Be aware of the national shortage of paralysis tick anti-serum due to increased demand.
• Monitor paddocks regularly, especially during high-risk seasons.