Monday 27 May 2013

The Fly Strikes Back

The smell is always a clue; wet fur mixed with urine and a hint of corruption. It's not too strong, but I've smelled it often enough that by the time I'd lifted the rabbit out of the box I had a fair idea what was going on even before his owner had told me what was wrong.

He's not eating, I was told. Depressed, not moving around much. Could he have caught a chill? I started to shake my head and look down towards the tail area, and that's when the first maggot landed on the table and confirmed to me that fly strike was back in season for another year.

Let's digress for a moment, if only to delay talking about maggots for a few more paragraphs (they give me the creeps... more on that later, though). There are some species that seem to have been dealt a particularly poor hand where diseases are concerned. From a large animal vet's point of view, it's sheep. If you can think of something unpleasant happening to a creature, then the creature it usually happens to is a sheep.  Cheesy gland, hairy-shaker disease, staggers, struck, braxy, foot rot, mouth rot and, yes, pizzle rot. Fly strike too, of course.

For the small animal vet, it's rabbits. As a species, rabbits have survived by being really, really good at making other rabbits. They're prolific, but not, on an individual level, very hardy. I've talked about some of the problems with being a rabbit before - there's many more pitfalls, the not least of which is fly strike.

Fly strike is probably not the best name for the condition (although it's certainly catchier than the official title of myiasis ) because the flies in question are neither forming a picket-line outside the rabbit's hutch nor physically thumping the rabbit - but an afflicted (or fly-blown) animal does look rather dazed as if it's just taken a left-hook, so maybe that's where the term came from.

So, here's what happens... the blowfly (lucilia sericata) likes to lay her eggs on tightly compacted fur, especially moist and smelly fur. She's keen on wool (which is why sheep suffer from this as well) and especially partial to rabbit fur. The eggs go on the fur, and within a short period of time (it varies depending on the temperature, but its often less than a day) the maggots hatch out. They burrow down to the skin, and they start to do what maggots do best. They start to eat.

Now, the more medically astute amongst you may be wearing a puzzled expression at this point. 'Hang on,' you're thinking, 'that's not right! Maggots only eat dead flesh, don't they? So they're not going to eat the rabbit alive, are they?'

Well, I'm very sorry to tell you that you're wrong, because that is exactly what they are about to do. It's true that, when clinically applied in sterile conditions, maggots of this very same fly have a preference for munching on dead flesh, and they are absolutely amazing in such situations at cleaning out (or debriding) all the necrotic tissue. Unfortunately, this is not a clinical, controlled situation. It's not even slightly a sterile one. It's probably technically true that the maggots are not so much eating the live flesh as killing it using acidic enzymes and inflammation caused by burrowing, and then eating the dead stuff, but such technicalities don't make a huge amount of difference to the unfortunate rabbit.

It's a quick disease - as I say, the maggots can hatch within a day, and the damage they can do in a short space of time is staggering. Unfortunately, because all this is almost always going on at the wettest, smelliest part of the rabbit - the anus and a genitals, both of which are hidden from a glancing view - all the owner tends to notice at first is that their rabbit has gone a bit quiet. The rabbits tend not to lick and bite at their burrowing attackers, possibly because there's a local anaesthetic effect (I really hope so) but more likely because doing so could be interpreted as a sign of weakness to a predator. Consequently, by the time we as vets are presented with a case of fly strike, the damage can be absolutely horrendous.

Fortunately, I have no pictures to display of the damage - firstly. I don't tend to take photos myself because when I see it I'm generally busy with the rabbit, and secondly, I'm not about to search for images of it because I've seen more than enough for this lifetime, thanks very much. You're very welcome to yourself, of course, but if you sensibly haven't done so, then I'll briefly describe the sort of things we see.

We're frequently presented with rabbits with what I would clinically describe as a 'large skin deficit' (and non-clinically as a 'big hole') often extending from the tail up over the back, or from the genitals forwards. If the rabbit is unlucky, the lesions will be deeper, extending into the subcutaneous muscles, through the perineum and on into the abdomen.  It's not infrequent to lift up the fur on a rabbit's back to have the skin lift up right along with it, revealing a white seething mass of maggots burrowing their way forwards through the gore.

A brief digression on maggots (for those of you who are still with me!) - I try not to discriminate between species. None of us were given a choice what species we were born. Even with ticks, which seem to make most people squirm with displeasure (especially when you pop 'em out with the legs still wriggling) I try and keep in mind that it's only doing what evolution designed it to do. It's not their fault they're a tick, is it?

I'm not capable of that with maggots. There's a strange atavistic revulsion that comes over me watching those little white bodies wriggle about like stubby Lovecraftian tentacles that makes me want to be sick, run screaming and destroy the abomination all at the same time. I'm not proud of it, but I also suspect I'm not alone amongst mankind in having such feelings. I know its not the maggots' fault and that it's stupid even ascribing such things as blame to the larval stage of an insect, but watching them wriggle in a kidney dish after plucking them from the living flesh of a rabbit makes me feel the need to buy a flamethrower and get all Ripley on their asses, as well as giving me all manner of dark thoughts about the nature of the universe. As ever, Darwin said it best...

'I cannot persuade myself that a beneficent and omnipotent God would have designedly created parasitic wasps with the express intention of their feeding within the living bodies of caterpillars.'

Ahem, let's try and get back to being professional. Fly strike is an emergency - the longer you leave it, the more trouble the rabbit is in. If the damage isn't too great already, we remove all the maggots from the wound site. That means physically plucking the maggots out with forceps, haemostats, cotton buds, fingers, and whatever else works to get them off the rabbit. We assess the damage - if the wounds extend into the abdominal cavity, or (as is also sadly not infrequent) we see maggots crawling out from the anus or the genitals, then there's no hope.

If there's a chance, then we clean the wounds, we treat for shock, pain, and infection, and we keep checking for maggots until they're all gone. So long as the tracks are not too deep, even very large skin wounds can heal surprisingly well; this may be some kind of testament to the healing power of the maggot even in these awful circumstances.

Well, there, that was less fun that it sounded at the start, wasn't it? Let's not beat around the bush - fly strike is horrible. Really horrible. Even to my clinically jaded eyes, it makes me feel full of horror and sympathy for its victims (victims? There I go again, as if the maggots are the criminals; it's hard not to anthropomorphise with this one).

Time is the key with fly strike. Get to it quickly, and it's easily fixed, or it never happens at all. Leave it too long and... well, you don't want me to go into all of that again, do you? Ugh. It made me feel queasy just writing about it, and it put me off my coffee. Shall we make a deal? You don't want to read about it again, and I don't want to write about it again. I definitely don't want to see it ever again. Here's a simple way to stop any of us going through it.

If you have a rabbit, check it. Check it every day - twice a day in Spring and Summer. Those eggs hatch more quickly than you think - clients find it often unable to believe the amount of damage in such a short space of time.

There's a few fly killers and fly repellents you can buy that you sponge around the back end of your bunny to try and prevent the eggs being laid or from hatching out. I'm not here to sell you drugs, but ask your local vet about them. They help. But they're not substitutes for checking. If you see eggs (like tiny little grains of sticky rice) get them off.

Your rabbit is going to be more at risk if it's overweight, less mobile, or if it has long fur. By far and away the biggest risk is rabbits with matted poo stuck around their back end, so clean it off! There can be a lot of clinical reasons for the mucky bum rabbits (teeth problems, weight problems, back problems, diet problems), and I'm aware some of them just seem to dirty protest however hard you try to prevent them, but you really need to be cleaning them daily and checking them more often than that in the Spring and Summer.

I know it's not a nice job, I know it's a pain, but I don't want to see another case of fly strike ever. Let's see what we can do.


  1. nick- thanks for writing this. you have an awesome sense of humor, mixed with compassion...this struck home, as last september, my boyf's. chow mix "max' suddenly displayed all the symptoms as you described; unfortunately, $$ is an issue for him sometimes, and we were waiting for checks to be deposited and cleared to schedule a vet.appt.--i was going to help pay for this...i loved max! unfortunately, on day three of these manifested symptoms, max suddenly yelped as he laid on the floor near the boyf'.'s couch--and was gone. within a three day, if even, span. i was not around when the boyf. carried max to the truck to take him for cremation at a nearby vet's office. however, he told me tearfully, that "nature had already started doing it's thing". further inquiry revealed that he had found MAGGOTS on max's body! i was appalled, but kept my composure. the vet (supposedly) did a very basic autopsy and said "it looked like" max had enlarged lymph nodes, and thought there was an eighty percent chance it was cancer that killed max. would this explain the maggots?? i wasn't confident with this diagnosis, and have wondered... when the boyf. acquired max, he'd been neglected, and was on his way to be euthanized. he'd had problems with his right ear....they were very foul smelling, and boyf.never got around to taking him for vet care. being part chow, he was very long-haired as well, but never was properly groomed or bathed, professionally, i am sorry to say. i am also sorry to say that i don't trust veterenarians very much, due to past experiences with my own ( now deceased) canine.for all i know, this one vet who saw max posthumously, may not have even BOTHERED doing an autopsy (sorry to sound so cynical here, doc...) ! how could he NOT have noticed or explained the maggots on poor max? he never ONCE even MENTIONED THEM to the boyf. ! this truly has been bothering me, so i googled "dog maggots"...and it surely sounds like fly strike to ME. what do you think? your opinion is appreciated (thank you in advance)...deb

  2. Hi Debbie
    I don't want to sound too legal and defensive, but despite that I've got to say that it's very difficult for me to talk about an individual case like that, without having all the facts or seeing Max - please bear in mind that I also live in the UK, which has a very different climate to other parts of the world, which may well affect the kinds of diseases that flies cause. I would, however, like to express my deepest sympathies for your and your boyfriend's loss of Max.
    What I will say - in general is that fly strike in dogs and cats is -much- rarer than in rabbits. They're far better able to fight it off, to clean the fly eggs off them and so on. This means that if they get fly strike, it's almost certain that something else has been making them so ill in the first place that they were unable to take care of the maggots. The point is - fly strike in dogs is usually secondary to some other condition, and it's very rare (at least in my practice) to be presented with a primary canine fly strike - in fact, I have never seen it.
    My heart goes out to you and your boyfriend, and I'm very sorry at the loss of your companion.

  3. Hi Nick

    My chow chow HAS fly strike, i noticed some faeces on his fur on Friday eve and was washing it off when i saw what i thought was a matt in the fur when i brushed it the shock nearly killed me there were absolutely hundreds of maggotts ! the ball fell onto the floor and icould then see a wound or thats what i thought but that was probably where the maggotts were eating their way in?any way my vets were closed and do not have out of hours so i got sme advice by phone was told to bathe area with salt water and get him checked in the morning. I stayed up all night with him and bathed every 2hrs the more i bathed the moremaggotts came out i was distraught and was counting the hours for my vet to open! They admitted him and called me to say it was much worse than they first thought as they were going from outside in and boring back out? they called me yesterday to say he is readyto comehome! but i am so scared and also where he had been in my hallway i have bleached and bleached with boiling water
    i am still finding some stray ones ? i have again spoken to the vets and they are saying he can come home but he is not eating today ? i am so so scared to bring him home what would you advise?

  4. Hi

    I think if your vet says he's ready to come home, you'll find he'll be less stressed and more likely to eat at home rather than at the practice. They'll probably have shaved the affected areas so that any stray maggots will be much harder to find and remove - so long as you keep a close eye on him he won't get anything like he had before. Don't feel guilty - these things happen very quickly. In the UK vets are legally obliged to offer some sort of out of hours service - not sure about where you are but I'd check what they advise out of hours so you're not in that position again.

    Best of luck for him, fingers crossed!


  5. Thank you so much will let you know, i live in London.

  6. Hi Nick
    I was hoping you could give me your opinion, Our lovely rabbit has today been subjected to Fly Strike to the extent I have never seen before. He is not the cleanest of rabbits and we have a lot off flies where we live due to living by marshland (we are in the UK).

    On previous fly strike occasions I have found the problem at either the egg stage or very small maggot stage and they had not eaten any flesh (disgusting things that they are!)

    Unfortunately today was much much much worse and by the time i discovered the problem the maggots had been eating away at the rabbits flesh.

    I immediately put him in the bath and showered him, where lots of the maggots came off him (so disgusting it was unreal!) - I then got an appointment with the emergency vet (Saturday Afternoon!) - He was given Ivermectin by spray, to kill any remaining maggots, Baytril liquid antibiotic and a cream for his skin where the flesh had been eaten. (I like many of your poor clients can't believe how much damage had been done by these things in such a short time since I last checked him).

    The area eaten away by these truely disgusting creatures was on both sides of his lower back to either side of his tail. The vet said he may need stitches to draw the skin back together again, but they would see how it heals in a week.

    It is now nearly 2.00am in the morning and I am sitting up checking on how our lovely rabbit is doing and generally worrying, he is eating some food but not much, but isn't drinking very much which concerns me. I have tried giving him water by syringe but this is distressing him and not much seems to be going in !

    I have spent all night reading accounts of survival or none survival of fly strike victims and I would just really like another opinion. The vet we saw today said that she was reasonably confident he would be okay, but I am still worrying.

    I know I am probably asking a question you can't answer but what are your thoughts on his survival chances based on what I have said ? (He is an old rabbit at 8 years old and I really thought I would not be bringing him home from the vets today !!!)

    1. Hello

      So sorry you and your rabbit have experienced this horrible condition; firstly I'd like to say it's always hard for me to comment on things like this without having seen the animal; that said, I'd like to reassure you that if your vet feels the skin will heal, I would be pretty confident too.

      The main problem with fly strike is when the maggots get in deeper than the skin; if they've eaten through very deeply then you're in very serious trouble indeed. In my experience, though, skin wounds - even very big ones - often heal surprisingly quickly. I suspect this is because the wounds, although extensive, are often very clean, so there's lots of potential to heal.

      He's been through a nasty shock (well, you both have!) but I would agree with your vet that even though he's an older boy, if the wound is superficial I think you'lll find it heals very quickly. If he stops eating or pooing at all, though, take him back to your vets quickly as the shock may have caused his bowels to slow down, which can be come a serious problem in itself.

      Best of luck to him! Give him my love

  7. Hi Nick
    Many thanks for your reassurance, it is much appreciated.

    Scrappy (the rabbit!) seems to be doing okay today....he has gradually eaten a little more today than yesterday and is a bit happier in himself. I found some more maggots today (this time around his genitals), although this time they were very small. I was quite shocked as I thought the Ivermectin he had been given yesterday would have killed them, or does it take time before the Ivermectin kills them and I possibly found them before the Ivermectin 'kicked in' ???? It was about 12 hours after the Ivermectin ???

    He was of course put back in the bath again (poor thing!) and all the maggots as far as I could see were again removed, I have checked him again frequently and have just checked him again, now about 10 hours since his last dunking and I can't see any more, so I truely have my fingers crossed he doesn't have to endure another dunking (although he is used to a 'bottom' bath as he isn't great at keeping clean - he has the run of the garden and eats very little processed rabbit food as he eats mostly grass and his hay, but I can't get to the underlying cause of his yukky bum problem, other than he is getting a bit old and less agile).

    My concern now is that I have maybe 'washed off' the Ivermectin and it will be less active against killing any further maggots I may miss ??

    I have an appointment for next weekend with the vet, but I am going to take him sooner just for them to check up on his wounds, as they look terribly gruesome to me, one of them is a large patch about 4 inches by 4 inches and the other is a smaller patch, but I just can't see how they will heal, I really hope that what you have said with regard to healing really quickly will be the case, as it looks so scary to look at. But thankfully neither I or the vet could see that the maggots had got in internally, so hopefully the prognosis is good,

    Many, many thanks for your time to reply and your caring words, it is much appreciated.....At times like these I wonder why I have pets as I find it so hard when they are ill or on pain.

    Many thanks. X