Blowfly Strike

Finally, the sun has come out! And as the temperatures have soared and grass grown, Blowfly Strike is suddenly a major risk to our sheep, camelids and rabbits. Taking as little as 3 days to go from fly egg to maggot, flies are attracted to any smelly fleece or fur - dirty bottoms caused by lush grass or worms, or wounds including foot rot. Getting the shearer in and applying a long-acting preventative to last the season is essential, but what can you do until then?

• Check all animals daily - any acting differently to the rest? any not grazing? any with discoloured fleeces or nibbling? This is actually a legal welfare requirement.
• Trim the fleece/fur around at risk areas - tail, rear end, or underbelly. 
• Treat any lame sheep, or other wounds promptly.
• Ensure your lamb worm control program is up to date.
• Fly prevention - manure, carcasses and stagnant water are all breeding areas so removal/management away from animals is important where possible, create fly traps, nurture dung beetles on your soil (natural predators). 

Diagnosis

Diagnosis is based on visual inspection: large numbers of adult flies are seen on the discoloured fleece with maggots on the blackened skin once the surrounding fleece has been lifted clear.  There is an associated putrid smell. Skin which has been previously damaged by flystrike may grow black wool.

Treatment

If maggots are found, they must be removed, a spot-on treatment applied to kill any remaining and the wounds managed with disinfectant, sometimes antibiotics, and importantly some pain relief. The maggots release nasty enzymes to digest flesh which causes a huge inflammatory reaction - this can become systemic, causing death in severe cases. 

Blowfly strike is a major animal welfare concern: an average of 1.5% of ewes and 3% of lambs in the UK may be affected each year, despite preventative measures undertaken by most farmers. This number will be much higher if no control measures are adopted. At least 75% of sheep farms report cases of blowfly strike each year. Flystrike of foot lesions causes severe non-weight bearing lameness, compounding the welfare implications of lameness alone. Death can result in neglected cases, with mortality associated with fly strike estimated at 5% of affected animals.

Unlike the situation for sheep scab and lice, most of the blowfly lifecycle occurs off the sheep and adult flies can travel large distances between farms.

Get in touch to discuss our Fly Strike preventatives in Sheep, Camelids and Rabbits