Flies are not just a buzzy pest….they can cause serious damage to your bunnies!
Fly strike is also known as Myiasis and is defined as “the presence of larvae of dipterous flies in tissues and organs of the living animal, and the tissue destruction and disorders resulting there from” (Boden, 2001). All very scientific…but basically, flies can lay eggs on bunnies and these quickly hatch out into maggots which eat the bunnies skin and organs 🙁
Initially, rabbits can hide fly strike quite well as the eggs and maggots are usually buried deep in the fur. “Bluebottles (Calliphora) and greenbottles (Lucilla) are attracted to soiled fur or infected skin to lay their eggs” (Harcourt Brown, 2002). The most common site for this to happen is around the rabbit’s anus and scent glands. A rabbit that is overweight, unwell or suffers from joint problems will struggle to keep this area clean. This can then lead to the fur being matted with urine and faeces, which attracts the flies. The eggs that are laid will hatch into larvae (maggots) in approximately 12 hours and will start feeding on external debris. Once this has been consumed, the maggots will continue to eat sound skin and tissue, often tunnelling under the skin layers. Aberrant migration brings the maggots deep under the rabbit’s skin, infiltrating vital organs and can even occlude the rabbit’s airway. This is very uncomfortable for the rabbit and will progressively get more painful as the condition progresses. Initially the rabbit will be very restless, however as time goes on it will become unwell, inappetent and lethargic.
The combination of the sore skin and the maggots creates a very pungent ammonia smell. This is because the maggots release proteolytic enzymes into the tissues to cause cell death and decomposition. These toxins can cause serious shock, septicaemia and if left untreated, will often be fatal.
For treatment to be successful, the rabbit needs to be seen by a Veterinarian as soon as possible. Depending on the severity of the case, the rabbit may have to be hospitalised for intensive therapy and monitoring for a few days. Rapid removal of the eggs and maggots is imperative to stop any further damage. This can be done by shaving the fur off the affected areas and then carefully using forceps to remove the contamination. This can be very time consuming and will need to be repeated a few times to ensure all of the eggs and maggots have been removed. The skin needs to be flushed and cleaned with a sterile saline solution and an antiseptic solution (such as povodine-iodine) and any wounds will need flushing and exploring to make sure that they are also clear of contamination. Non-steroidal pain relief and fluid therapy are vital to help the rabbit combat shock. Not all patients will be well enough to endure a sedation or anaesthetic at this point so care needs to be taken and close monitoring performed. The rabbit will need to be dried well and placed in a clean, warm and quiet area. Sometimes the use of topical creams like Dermasol (by Pfizer) is advised as it promotes healing of areas impaired by the presence of necrotic tissue because it activates the sloughing of devitalised tissue. Intensive nursing will also be vital to the success of the treatment. The rabbit will need regular syringe feeding, medicating and cleaning along with trying to keep its environment warm and as stress free as possible. F10 wound spray with insecticide can be used on the area – helping the wound and protecting from further fly problems too. This can be used daily and is good for disabled rabbits that need daily clean ups (thus washing off any Rearguard etc).
If there is a heavy maggot burden, injections of Ivermectin can be given to kill the maggots but the patient must be very closely monitored as the dying larvae excrete toxins that can be fatal. The final treatment option is surgery for when the maggots have migrated far under the skin. However, such a heavy burden does not have a good prognosis and often euthanasia is the kindest option for severe cases.
WARNING! F10 wound spray is TOXIC to cats. Do NOT use on cats or in households where cats and rabbits have direct contact.
As always, prevention is better than cure and there are a number of things that owners can do to help reduce the risks. Owner awareness of fly strike is vital and they must be able to recognize the signs and know that this is an emergency that needs Veterinary attention as soon as possible.
In general, it is very important that the rabbit is kept in good physical condition. This means that it is fed a balanced diet consisting mainly of good quality hays with a small amount of commercial rabbit pellet and fresh vegetables and herbs. By feeding the correct diet, it reduces the risk of the rabbit becoming overweight and also reduces the risk of over producing caecotrophs which get stuck around the anus. Rabbits that are very young, very old or have health problems such as dental, gut or paralysis issues are more susceptible to fly strike.
Next, it is important that the rabbit is kept in clean, spacious living conditions. Any build up of urine or faeces will attract flies. The rabbit should also have plenty of space to move around and exercise away from its toileting area and uneaten fresh vegetables etc should be removed daily. If housed outdoors, mosquito netting can be used over the hutch and run areas to help reduce the amount of flies that can enter the area. It can also be attached to windows / door areas too. Sticky fly paper can be used outside the hutch but never in an area that the rabbit has access to as it can stick to them and cause terrible damage. If the rabbit is housed indoors, an electric insect killer can be used in the same room as the rabbit is housed and net curtains can be used in the windows to reduce the amount of flies entering the room.
Lastly, a topical treatment can be applied to the rabbit to help prevent fly strike. F10 wound spray with insecticide and Rearguard are examples of these topical treatments. F10 wound spray needs to be applied weekly to the rump and genital area. It is TOXIC to cats so don’t use on cats or in households where the cats and rabbits interact.
The main ingredient in Rearguard is Cyromazine (an insect growth regulator). It is recommended by many Veterinary practices and is widely available in pet shops and online. It should be applied at the start of summer before any flies are seen and gives approximately 8-10 weeks of protection. This product does not repel flies or kill maggots but works by preventing any eggs laid on the rabbit from hatching into maggots. Rearguard can also be applied on rabbits that have been successfully treated for fly strike to help prevent re-occurrence.
The bottle comes with a sponge applicator but I find this often has a sharp spike in the middle. So I wear a pair of disposable latex / nylon gloves and apply the liquid to my hands. I then rub this into the rabbits fur from the middle of the back to the tail and the same on the underside. Its important to get the fur quite wet and apply well around the back legs and genitals.
DO NOT APPLY TO SORE OR BROKEN SKIN.
The bottle says to use the whole bottle per rabbit but I have found that you can often get 2-3 applications out of one bottle for small / medium bunnies. As long as the target area is covered and the fur quite wet then this should be fine.
Re-apply every 8-10 weeks.
See here for more info (WARNING! some contain graphic images):
Really??? Are you 100% sure???
You may be shocked to find out that not all Vets are well trained in rabbits 🙁 Many can have as little as a 2 week slot for exotics as a whole (including reptiles, birds and small furries). This means that the majority of Vets out there have very little knowledge of rabbits needs, behaviours, ailments and how to treat them correctly.
The Royal College of Veterinary Surgeons (RCVS) released a statement for Rabbit Awareness Week 2014 which briefly explains how vets can be accredited (but this is not species specific). A student Vets training changes depending on which University they attend. Some, Like The Royal Dick in Edinburgh and Bristol University have some VERY rabbit savvy lecturers (Like Anna Meridith, Kevin Eatwell, Brigitte Lord, Emma Keeble, Jenna Richardson and Richard Saunders. This means the graduates have a higher level of rabbit knowledge.
Of course, there are a host of fabulous Veterinary textbooks that are written by top rabbit specialists but not all Veterinary Practices have these in their library.
So…what can you do?
Well – a rabbit savvy Vet is worth their weight in gold and it is VITAL that you find one before you need them. For those of you in the UK you can contact the Rabbit Welfare Association and Fund (RWAF) as they hold a list of good rabbit vets located across the whole of the UK.
For those in the USA then you can contact the House Rabbit Association as they hold a USA wide list. This forum, Bunny Lovers Unite, has a list of good rabbit vets worldwide that has been complied by its members experiences.
It is important that you as an owner, understand what makes a good rabbit vet. This will help you to find out if your current vet knows as much as they should to help treat your pet.
1) The most important aspect in my opinion is pain relief. Rabbits are prey species and hide their pain very well. Many, un savvy vets will believe that rabbits do not routinely need pain relief. THIS IS NOT TRUE!!! In most cases a sick rabbit will be experiencing pain and will need a good non steriodal anti inflammatory drug to help control this (Meloxicam is the drug of choice for pain control in rabbits and can be found under the brand names of Metacam, Loxicom, Meloxidyl and others). Although it is not technically licesnsed for rabbits – it can be used under the cascade system and the vet may ask you to sign an ‘off license’ agreement form. Bear in mind that there are hardly any drugs licensed for rabbits (even though almost all of our human and Veterinary medicines have been tested on rabbits at some point). Adequate pain relief should be given routinely after rabbit neutering as well for at least 3 days post op.
2) Never starve your rabbit before an operation. Walk away from any Vet who recommends this! Generally, mammals are starved before an operation (humans included). This is to reduce the risk of the patient vomiting whilst under general anaesthetic. Rabbits cannot vomit so do not have this risk. Also, a rabbits metabolism is high and their guts are sensitive – it is imperative they continue to eat frequently (up to approx 1 hour) before their operation. Also, the Vet should not discharge the rabbit after an operation until it is eating and passing faeces.
3) All rabbits (that are not being used for breeding) should be neutered. Any Vet that disagrees with this fact (especially for female rabbits) is questionable. Female rabbits have an 80% risk of uterine cancer. This is the main reason to neuter (more so than accidental litters). Add to this the fact that un neutered rabbits can display unwanted behaviour changes such as becoming more aggressive and territorial, spraying urine, humping and generally being more stressed. So always spey the females and castrate the males to give them the best chance at a happy healthy life.
Lastly, if you really like your current vet and do not want to change – you can always ask them to contact rabbit specialists if ever your rabbit gets sick. The RWAF offer a Veterinary Membership which practices can sign up to. This give them lots of benefits – one of which is direct access to Richard Saunders who is one of the UK’s top rabbit specialists. Even if your Vet will not sign up to this scheme, many rabbit specialists will offer advice to other Veterinarians for a small fee.
For more info on finding a good UK rabbit savvy vet click here.
For more info on finding a good USA rabbit savvy vet see this article here.