News & Advice

Animals being eaten by flies and having animal food destroyed by vermin are both conditions that require prevention and control and which both have potential negative animal welfare outcomes.


Flystrike is something we can see in any class of animals from dogs with hotspots under long coats, cats with abscesses, chickens with wounds through to sheep with dirty tails and cows with skin cancer lesions. It is caused by flies laying eggs on the skin or coat of animals which may be damaged or soiled, or may be quite normal. The eggs hatch out into maggots which then start to consume the animals’ living flesh. The animals are distressed as they can feel those maggots moving around and they cause intense pain and irritation. Also, the maggots release juices to digest the flesh they are living in, so the wounds are difficult to heal because the neighbouring flesh is being dissolved in situ by digestive enzymes (uugghh!!). The good news is that prevention works!

In the case of sheep, farmers routinely apply dips and sprays to prevent flystrike. They also keep the fleeces clean with regular crutching and worm control. If a sheep becomes flystruck then your veterinarian can supply you with products that will knockdown the maggots as well as the eggs.

If cows become flystruck there are a variety of products that will do the same thing, but your veterinarian will advise which are registered for use on cows.


Control of vermin is important to prevent damage to silage stacks which allows air spoilage and contamination of foodstuffs with urine and faeces. Both rats and mice may be infected with several different serovars of leptospirosis, and not necessarily the same as what the cattle are vaccinated for. These are excreted in their urine and can affect calves, cows and humans eating, drinking and handling the effluent around the stack and the contaminated silage or foodstuffs. The disease in cows and calves can be asymptomatic (no signs) or they can have a severe fever and kidney problems (more common in calves). From a human aspect getting leptospirosis has serious health consequences ranging from flu like symptoms through to meningitis, kidney and liver failure. So vermin control is important!

However, many of the products used as a poison are both directly poisonous to other animals if eaten and indirectly via eating the dead vermin or insects, i.e. secondary poisoning. Therefore, it is important to only put poison baits out in prescribed numbers (read the instruction on the container!) and to make sure that other animals cannot get into the station, nor can the baits be half consumed and dragged out. Dogs and cats are both susceptible to direct and to secondary poisoning as the baits are very palatable, not only to mice and rats.

Last year I lost a puppy to secondary poisoning – he ate a young rabbit that had eaten a rat bait. As a consequence, I no longer use the tunnel bait stations that young rabbits can walk into. If you find rat and mice carcases, disposing of them away from where they can be eaten by your pets is a good idea. If your dog or cat is sick and you are using rat baits, do let your veterinarian know as they can rule out poisoning with blood tests.

For more information, regarding flystrike or vermin control please contact your local Anexa vet.

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