Tick fever in cattle - UQ VETS - University of Queensland

Paralysis ticks can be deadly for calves and small breeds of cattle. See the preventative measures you can take to avoid toxic tick fever.

Tick fever is caused by the red blood cell (RBC) parasites Babesia bovis, Babesia bigemina and Anaplasma marginale.

It is transmitted between cattle by cattle ticks.

Tick fever is 3 times more common in Bos taurus cattle than in Bos indicus cattle, which have an inherent resistance to cattle tick.

Maternal antibodies from resistant dams protect calves to around 3 months of age and calves have an inherent resistance to around 9 months of age.

What to look for

Clinical signs

Clinical signs show within 14 days (Babesia spp) and 45 days (Anaplasma spp) of tick attachment:

fever, anorexia, rumen stasis, diarrhoea, dehydration (sunken eyes)
HR, RR
red urine (not in anaplasma)
pale mucous membranes (anaemia) and/or jaundice
B.bovis infection may show terminal nervous signs including aggression, convulsions, paralysis as CNS capillaries stick (toxic metabolites released from RBCs)
death from toxaemia cf B.bigemina where primary cause of death is severe anaemia.

Differential diagnoses

Bracken fern toxicity
Chronic copper poisoning
Contagious bovine pyelonephritis
Dimethyl disulfide poisoning – Brassica spp, onions
Internal parasites
Leptospirosis in calves
Liver disease
Periparturient haemoglobinuria
Septicaemia
Theileriosis.

How to treat and prevent ticks

Treatment

Babesia spp – Imizol (Imidocarb) 1ml/100kg SC (WHP milk 14 days, meat 28 days).
Anaplasma spp – Imizol 2.5ml/100kg SC (WHP milk = entire lactation) or Alamycin LA 300 20mg/kg or 2 x short-acting 10mg/kg (WHP milk 72hrs).
Vaccinate against tick fever 8 weeks after Imizol therapy. In the interim protect with Taktic (amitraz) every 5 days to prevent tick attachment, feeding and therefore transmission of tick fever organisms.

Prevention

Immunity is lifelong. Aim to induce immunity during the period of inherent resistance (up to 9 months) by vaccination.
Tick fever vaccine 3 germ = B.bovis, B.bigemina, Anaplasma.
Once-only dose before 9 months old (from as early as 6 weeks if no maternal interference – may require booster if calves are younger than 3 months).

When to vaccinate

The tick fever vaccine is immunosuppressive so don’t administer other vaccines at the same time. Administer other vaccines 2 weeks before or 8 weeks after the tick fever vaccine.
Vaccination can induce disease in animals older than 12 months – signs become evident from 8 days after vaccination.
Vaccinate no earlier than 8 weeks after Imizol treatment.

Tick control

Acaracide treatments every 19 days from tick rise (in spring).
Amitraz (Taktic, Amitik) – spray or dip, 10c/dose. No WHP [withholding period] milk.
OPs and SPs (Barricade S, Blockade S) – widespread resistance.
Macrocylcic lactones (Cydectin) 1ml/10kg – pour on (not protective against tick fever).
IGRs (Acatak) – doesn’t kill larval stages so no protection against B.bovis, not to be used in dairy cattle.