Insect Bites: from Itch to Anaphylaxis

With our patients running around in nature, naked, and fascinated by all things moving, insect bite reactions are a familiar presentation for vets. Pets roaming backyard or paddock landscapes are at greater risk, but mysterious allergic reactions can also erupt in the housebound. Rarely life-threatening, this is one disease many pet owners quickly learn to diagnose and treat themselves, as animals don’t seem to learn, making repeat outbreaks frustratingly common. Here are some pointers on symptoms, treatment, and prevention.



Offending insects

  • Bees:                 Native and Honey. Picture gallery
  • Wasps:              Mud, Paper, European, and many others. Picture gallery
  • Ants:                 Green, Fire, and many others. Picture gallery
  • Biting Flies:     March, Stable, Midge and many others. Picture gallery
  • Others:             mozzies, spiders, scorpions, centipedes, and many others.

For more specific information on spider bites in animals, see here.

Looking for clues of insect bite

  • Your pet was outdoors, immediately prior to onset of symptoms.
  • Flowering plants, especially lawn clover, will attract swarms of bees.
  • Ants are often more active during rainy weather, or may be attracted to pet food bowls.
  • Wasps often attack when in open paddock landscapes and orchards.
  • Remove all your clothes, get down on all fours, and roll around in the area of the garden the pets commonly play.

What else could it be?

  • Food allergy is always a possibility, especially if any unusual foods were consumed in the 30 minutes prior to onset. I’ve seen such reactions in dogs dining on compost, indian takeaway leftovers, and eggs.
  • Drugs of any kind, but most notoriously vaccinations and penicillins, injected or oral, can cause dramatic allergic reactions. While many side effects of drugs are foreseeable, allergic reactions are rare and unpredictable, so don’t give your vet too much grief if his prescription unwittingly triggers hives.   For more on the character and timing of adverse drug reactions, see Drug Allergy: underrecognised?



Typical presentations

Acute lameness

Often non-weight bearing, with whimpering and frantic licking at a paw, this is typical of bee or ant sting. Unless the patient is allergic to the venom, the experience for a dog is probably no different to ours: intense, sharp, transient, local pain. Usually, by the time the patient arrives at the vet, the symptoms are abating. Within a few hours, most pets are walking normally.


A common manifestation of insect bites, resulting in dramatic facial swelling, usually around the eyes and lips, sometimes ears. Often intensely itchy, many patients will frantically rub face, shake head, and the scratch anywhere.  Deemed to be of greater risk of breathing complications, this type of insect bite reaction is treated more aggressively in both man and animal. This may occur in concert with…

Hives or urticaria

Lumps erupting, initially close to the bite site, then spreading over the body. Easily visible in slick coated dogs, like Boxer or Staffy, these may go unnoticed if covered by long hair. Itchy and persisting from hours to days, they may turn scabby.

Crusting of ear tips, around eyes, or bridge of nose

Many bloodsucking insects can’t penetrate dense hair to feed, and will target these exposed areas of skin with good blood supply. Any pet  who spends much of the day outdoors, especially at dawn and dusk, with seasonal symptoms of scabby ear tips and eyelids, may be suffering this low grade, chronic form of insect bite reaction.

A trial of insect repellant will usually see an improvement in a week or two. Ears and eyelids easy to treat, while nose and muzzle lesions, within striking distance of tongue, may require non-toxic repellents.




Secondary bacterial infections

These may erupt spontaneously, or secondary to self-trauma by the patient. Appearing as scabs or hot spots, they may require topical or systemic antibiotics.

Breathing difficulty

Swelling and occlusion of the throat is commonly feared, although rarely seen. It’s more likely in pets bitten on the face, mouth or neck, and those with angiooedema.

The warning sign of this complication is frequent swallowing or stridor: upper respiratory noises like those of a normal Pug or Pekinese. These breeds have such crowded throats, they can barely breathe when healthy, and any acute allergic reaction in short-faced dogs should be considered a potential emergency.


Only included here as I’ve seen a case myself. A rare, immune-mediated complication of multiple green ant bites can be subsequent swelling of joints and lameness on multiple legs; responsive to a few weeks of non-steroidal anti-inflammatory.


Like the peanut-allergic child dropping dead in the schoolyard, very rarely a dog or cat may suffer a severe allergic reaction that affects heart rhythm or blood pressure, resulting in collapse, sometimes vomiting or diarrhoea, loss of consciousness, and possibly death.

In both man and animal, anaphylaxis typically strikes when outdoors, and if accompanied, on a walk, such symptoms may put pet owners in to shock, thinking their limp dog is dead. Pets and their owners often regain consciousness during the ambulance ride to hospital, those which don’t may, or may not, be resurrected by medical intervention.

Given a regular allergic reaction can escalate to anaphylaxis within minutes, and pets spend much of their time alone, any young, healthy backyard pet found dead could be victim of anaphylaxis.  Pets whose allergic reactions seem to be escalating are of greater risk, and an epipen may be a good investment.


The incidence of acute allergic reactions in man is soaring. Foods are the most common trigger in the young; adults more usually insects and medications (esp. penicillins). Hospital admissions for anaphylaxis in the US and UK have increased  2-3 fold, per decade, from the 1980’s. In the UK, childhood peanut allergy doubled in frequency in the 4 years to 2005. The widescale availability of Epipens, for self administration of adrenaline, is saving thousands to these patients annually.

The cause of this increase remains unknown, although it’s rate is too fast to be explained by genetic change in the population, leaving environmental and lifestyle factors. For more on this see ‘the hygiene hypothesis and its implications for animals‘.

I’m definitely treating more acute allergic reactions  than 15 years ago, but this can at least partly be explained by a move from urban to rural surrounds. Without any broadscale collection of epidemiologic data in companion animals, we won’t be able to say if pets are suffering the same increase in anaphylaxis as man.



First aid and Treatment options

Quickly scan the environment for insects or snakes in the pet’s vicinity immediately before the symptoms began. Also think food, and drugs.

In those pets frantically licking a paw, ideally remove bee stings and apply ice, although this may not be realistic in an agitated dog with hairy toes, who won’t sit still. An icewater footbath may be a good alternative.

Antihistamines are only really effective against allergic reactions when given before exposure to the allergen. Without such foresight, the effect of antihistamine pills, given by owner as first aid when vet services aren’t nearby, will be sufficiently delayed to be of questionable benefit. The sedative effect, calming a dog driven mad by their insect sting, may be of more help than suppressing the allergy.  For doses, see DIY Antihistamines.

That being said, most vets treat with injections of corticosteroid and antihistamine. Adrenaline is given if exhibiting signs of anaphylaxis, although this is rare. Animals may be hospitalised for brief periods, especially if reaction is severe or in its early stages, to ensure the patient stabilises.

In cases of repeated insect bite reactions, over days or weeks, pets may be prescribed a course of pills to prevent further outbreaks while the owner can trace and eliminate the source.

Given mild allergic reactions can escalate to anaphylaxis within minutes, Epipens, or the cheaper option, a regular syringe with a single dose of adrenaline, can be kept on hand for pets with escalating allergic reactions to insects that can’t be eliminated or avoided.

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18 Responses to “Insect Bites: from Itch to Anaphylaxis”

  1. antonia staff says:

    very informative. especially the ice bit. thanks.apis homeopathic also helps.antonia

  2. matt says:

    thanks antonia, many owners report rescue remedy seems to help also.

  3. Kelsey Cornelius says:

    Dog had a bite of some kind on the lawn tonight. Within about :30 seconds, she was drooling excessively, lethargic and limp. A few moments later, she had a BM on the rug in the living room. We rushed her to the animal ER, where she was given cortisone and benedryl injections.

    She’s fine now, but I’m concerned… do I spray pesticides to keep bugs out? Is there anything more preventative then giving her a tea tree bath weekly to deter bugs? She revived on the car ride to the vet on her own, but will she always? I’m afraid to let her outside unattended!!

  4. matt says:

    Your concern seems justified. Reactions as dramatic as you describe will often reoccur and may escalate. Speak with the vets who attended: if they believe the reaction to be allergically mediated, which would be suggested by the drugs given, then givng oral antihistamine tablets in the short term, until you identify the cause, may avert another episode. An epipen may be in order if you cant identify or eliminate the source. Good luck.

  5. Kate says:

    We live on a farm in south-west NSW and one of our Kelpies is having a lot of trouble with fly bites to her ears. I have read that Advantix is a good product to use. Does it need to be applied to the ear tips only and if so how much? We use Advantage for general flea control but would this repel the biting flies and mosquitoes?

  6. matt says:

    Hi kate, you’d expect many topical spot ons (frontline, advantage, revolution etc) to have some toxic effect of blood-sucking, flying insects, but on a practical level these agents rarely seem to have enough repellant activity to prevent your problem.

    These chemicals may kill the offending insect but only after its already bitten the dog, and if she lives outdoors amongst a localised mozzie or midge plague, there are countless footsoldiers to replace those killed.

    Repellants? yep advantix has a claim, which is worth testing, but I wouldnt be surprised if performance falls short. yep, applying directly to ears will achieve higher concentrations but i’d avoid applying anything to already inflammed ear tips.

    Other agents with repellant activity you can use sparingly in ares of skin not accessible to mouth include, DEET, Permethrin ( Permoxin), or natural Neem.

    If you find a repellant that works well, let me know. Speak with your local vet about treatments to accelerate healing of the pre-existing dermaitis.

    hope this helps.

  7. Hey could I quote some of the content found in this blog if I reference you with a link back to your site?

  8. matt says:

    no problem

  9. Darryl Watts says:

    Good afternoon, I have an 8 month old Boxer whom I found this am when I woke w/ an onset of mild to moderate Hives throughout her body. We live in a condo, with a enclosed porch on the third floor. It is highly unlikly that she consumed any food or medication. On our porch is several wine barrel planters, that she occasionaly will dig in. I found that she had been digging in one of the wine barrells this am. I contacted my vet, who advised me to administer 25 mg of oral Benadryl, and based on her weight could take up to 50 mg. An hour has passed, the sedative affect is now working, and the hives have not progressed. My only thoughts are a Bee or spider bite? Any thoughts or concerns?

  10. root says:

    hi darryl, i’d put money on an insect in the planters, although airborne insects are possible, especially if the plants are flowering. its only really important to identify the cause if there are repeat episodes with escalating severity. the treatment is appropriate and dont heritate to go to the higher dose if it happens again.

  11. marko says:

    Whats up very cool website!! Guy .. Beautiful .. Wonderful .. I will bookmark your site and take the feed

  12. Phill says:

    Hi. two days ago my female boxer dog went into a severe anaphalaxic shock due to a wasp sting. Within minutes she vomited and became double incontinent before going unresponsive. The emeragncy vet treated her with fluids and steriods and she has made a great recovery. The next day she was incontinent every hour and the vet explained it was due to the amount of IV fluids she had the night before. My only concern is that another day has passed and she is still incontinent…and looking pretty glum about it too. Is this normal to still occur two days later and will it stop?

    many thanks

  13. Misty says:

    My american bulldog mix has constant hives, we have spent thousands on allergy testing and various diets and now he is on a steroids/antihistamine mix to calm his erupting skin but it still only works as long as he is taking them. We have relocated and changed everything over a period of time and still no results. He is about to be 4 and this started at about 1.5yo. My question, Has anyone else come across this issue and if so has anyone come up with a result that worked?!?! I am to the point that I just want him to be comfortable and in all reality, if he was any less of a dog I would have put him down but he is the absolute best. Anything would help, thanks!

  14. admin says:

    While not wanting to condemn you to more insane vet bills, it sounds like its time for a cyclosporin trial.

    Speak to your vet about atopica.

    Does he suffer similar problems when at other peoples houses? or on holidays? if not, you could move house.

  15. Liz says:

    Having just read your site i think my baby (5 month old staffy) is suffering from hives. He comes up in bumps, only ever appear on his back legs, and his rump, never on his front legs, head or chest and only a few bumps on his tummy. He also has thining hair, not losing hair in clumps just thining all over. Originally i thought the bumps maybe mosquito bites from sitting in his splash pool but we tipped all the water out – no change. His food changes fairly regularly. I thought maybe plants cause this reaction but woud the hives not also show up on front legs if caused by walking through plants? He recently had an infection which was treated just fine by anitbiotics. Any thoughts? how best to treat itch?

  16. admin says:

    i’d be thinking a a biting insect that hes sitting on, perhaps? ants?

  17. Jahni says:

    This was very helpful. I have a 9 month old Pittwiler named Avenger who has bumps all over. They are sensitive, and itch so that he made little bald spots, and sometimes bleed, ( I stop him when I see him ). We took him to the vet and she gave us a pill to give him and a drop to apply directly. I think it has helped because he hasn’t been biting at himself as much. I think they are ant bites after having read this information. He was at my sisters and her yard is literally cover with ants!

  18. Eryn says:

    My year old cocker spaniel lab mix was outside in the dog run yesterday, when I went to get her she looked just like the dog in the above picture, but she has been vomiting? Do I need to go to the vet?

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