Flystrike in Small Animals

Up to 50% of rabbits diagnosed with Flystrike die, or are euthanized because of it, so it is important we know the signs and what measures we can take to help prevent it.

Created: 4/27/2022 Updated: 1/19/2024 - Vicky Payne

grooming, health, Health & Wellbeing, parasite, rabbits, small pet

What is flystrike?

Flystrike, also known as myiasis or being ‘fly-blown’, is a painful and often fatal condition where maggots eat away at an animal’s flesh. Flies are attracted to animal housing, especially if this has been allowed to become dirty. They lay their eggs on the animal’s fur and maggots can hatch out in as little as a day.

The most common fly causing flystrike in the UK is the Green Bottle (Lucilia sericata). Maggots won’t eat healthy tissue but will find any skin that is damaged by prolonged contact with urine or faeces. If the wound is contaminated by urine and faeces, more tissue dies and is eaten by the maggots. Flystrike causes rapidly growing, painful wounds and can cause septicaemia (infection in the bloodstream) and toxaemia (toxins in the blood) from the dying tissues.

Rabbits are the pet most commonly affected by flystrike, but guinea pigs are often victims too. Any animal can be affected. Although treatment is possible, up to 50% of rabbits diagnosed with flystrike die or are euthanased.

The life cycle of a fly

There are four stages to the life cycle of Green Bottles

Egg: Fly eggs are very small, just over 1mm long and less than 0.5mm wide. Individually they are hard to see but en masse they look like a clump of sawdust.
Larva: The eggs hatch into larvae, commonly called maggots. The larvae eat dead animal tissue and grow rapidly, going through three developmental stages. After about 10 days the maggots pupate.
Pupa: The pupae have hard, brown shells and are about 10mm long.
Adult: After another 10 days, the flies emerge from the pupae and can breed and lay eggs in around one week.

Under optimal conditions eggs can hatch in as little as 18 hours! The maggots can cause extensive damage to weakened tissues in just one day. If eggs or maggots are seen on a pet, veterinary attention should be sought immediately for the best chance of successful treatment.

Signs of flystrike in small animals

Signs of flystrike include:

a strong smell coming from their hutch
your pet appears tired or unwilling to move about
food not being eaten
water not being drunk
loss of fur, particularly over the rump
wet fur, especially around the bottom
a dirty bottom
open wounds
eggs or maggots visible in the hutch or on your pet

Many of these symptoms are not exclusive to flystrike, but all indicate illness that requires urgent veterinary attention. If you see eggs or maggots do not attempt removal yourself but contact your vet for an emergency appointment. Book any companion animals in too, even if they seem unaffected.

What puts your pet at higher risk of flystrike?

Even the best cared for pets are at risk of flystrike, but the following list contains some of the conditions which may put your pet at higher risk:

open wounds
diarrhoea (caused by illness, diet, or parasites)
warm weather, especially damp warm weather
immobility, due to pain, illness, or an unsuitable hutch
any condition which stops a rabbit eating their caecotroph (including dental disease, mobility problems, and other illnesses)
obesity (because it increases skin folds and prevents normal grooming)
unsuitable litter or housing
dirty fur, especially in longhaired rabbits and guinea pigs
poor cleaning of the hutch and run
injury, arthritis, or age-related conditions that reduce mobility and grooming
dental problems, which hamper grooming and reduce caecotroph ingestion

Brown fluffy long haired rabbit in outside cage thumb

Caecotrophy and flystrike

Failure to ingest caecotrophs is an indicator of pain or ill health in rabbits and is a risk factor in developing flystrike. Because rabbits eat a very fibrous diet their digestive system needs to process food twice. The caecum produces a dark, sticky dropping called a caecotroph once a day (usually overnight) which is eaten straight from the bottom for further digestion.

Caecotrophs are dark and sticky and often have a strong odour and will not be seen in the housing of a healthy rabbit. Normal droppings are lighter in colour and fairly dry and may be deposited in a specific area. Diarrhoea may vary in colour and can be produced at any time of day.

Other small pets including guinea pigs and rodents will also re-ingest faeces in order to extract the maximum possible amount of nutrients.

Because the caecotroph is sticky and stronger smelling it can easily stick to the fur if it is not ingested: causing skin irritation and damage which attracts Green Bottles.

Rabbit in the shade on the grass with a bowl

Flystrike prevention

Flystrike requires intensive veterinary treatment to counter pain, shock, and infection, and to treat wounds. Up to 50% of affected rabbits die or are euthanased. Thankfully, most cases of flystrike can be prevented by following simple precautions:

Choose suitable accommodation for your pet. Your pet should have ample room to move around with separate areas for sleeping, eating, and toileting. Choose absorbent bedding such as Back-2-Nature
If your pet lives outdoors it may be possible to reduce the access of insects using netting or chemical free traps.
Your pet’s home should be cleaned thoroughly at least once a week. Litter trays or toilet areas should be cleaned daily. Use pet safe cleaning products such as Beaphar Deep Clean Disinfectant
Check your pet’s bottom at least once a day. Seek veterinary advice if you see caecotrophs, evidence of diarrhoea, urine scalding, or skin infections.
Groom your pet regularly if they are unable to groom themselves. Choose a suitable brush for rabbits and guinea pigs such as the Pet + Me Brush
Long-haired pets may need to have hair clipped away from their bottom and genital area. Seek help from a pet groomer if you aren’t confident about doing this yourself.
Use a spray containing ivermectin designed to protect against Flystrike. Beaphar fly guard is a easy-to-use spray veterinary strength medicine containing ivermectin designed to prevent flystrike in rabbits and guinea pigs. Fly guard effectively protects your pet for three months after application and is suitable for rabbits and guinea pigs over 10 weeks old.
Contact your vet immediately if your pet seems unwell, or if their behaviour changes.
Feed a hay-based diet to reduce the risk of dental disease, intestinal upsets, and obesity.
Make changes to the diet slowly to avoid diarrhoea.
Balls of part-chewed food and wetness around the mouth are early signs of dental disease. Seek veterinary advice if you notice these signs in your rabbit or rodent.

Fly strike is a painful and often fatal disease; however, it can be prevented. Key factors in avoiding flystrike include good hutch hygiene, observing for health problems, seeking early veterinary attention, and daily handling of pets to ensure they are clean and free of injuries and fly eggs.

Do you need further advice?

If you need any further advice, please contact the OSCAR Helpline Team on our freephone number 0800 195 8000 or email helpline@oscars.co.uk.