Insect stings and allergic reactions in dogs and cats

The first thing to understand is not which insect did the stinging, but how far the reaction is spreading. A local reaction stays confined to where the sting happened: swelling, redness, pain or itching at that spot and nothing more. A systemic reaction instead involves organs far from the sting site, because the immune response has spread through the whole body, and its most severe form, anaphylaxis, is an emergency that can lead to collapse and death if untreated.

Localised swelling on a paw after a bee sting, in a dog that keeps behaving normally, almost always belongs to the first column. A face that swells before your eyes, hives appearing across the whole body, or an animal that suddenly vomits, staggers and struggles to breathe belongs to the second, and it is not a situation to handle alone.

Anaphylaxis is the most severe allergic reaction. It does not depend on the dose of venom but on individual sensitisation: an animal that has already met that allergen in the past can react excessively to the next sting. What makes it dangerous is the speed, because it can go from a first sign to a severe picture within a few minutes, and every minute lost counts.

• Rapid swelling of the face, lips, eyelids or throat.
• Widespread hives: welts and blisters on the skin, often visible first on the belly and inner thighs where the coat is thin.
• Sudden vomiting or diarrhoea, sometimes with heavy drooling.
• Violent, sudden itching all over the body.
• Weakness, pale gums, tremors, an unsteady gait progressing to collapse.
• Laboured, noisy or open mouthed breathing, which in a cat is always a serious sign.

In the first minutes after a sting the job of whoever is with the animal is simple: assess severity, remove the cause if possible, keep the animal calm, and decide quickly whether this is a case for observation or for the clinic. Here is the sequence to follow.

1. 1

   Check the general state right away

   Look at whether the animal is breathing well, standing, whether the face is swelling and whether hives are appearing on the skin. It is these signs, not the pain at the sting site, that tell you whether you are facing an emergency.

2. 2

   Move it away from where the sting happened

   If it is near a nest or a swarm, move it calmly to avoid further stings. Multiple stings increase the amount of venom and the risk of a severe reaction.

3. 3

   Find and remove a bee sting

   Only the bee leaves its stinger embedded. Scrape it out sideways with a fingernail or the edge of a stiff card, without pinching it between your fingers, so you do not squeeze more venom into the skin.

4. 4

   Reduce local swelling with cold

   A cold pack wrapped in a cloth, held on the area for a few minutes, helps contain swelling and pain. Never put ice directly on the skin, and do not use home remedies or creams without the vet's advice.

5. 5

   Do not give medicines on your own initiative

   Human antihistamines, anti inflammatories and steroids can be toxic or harmful to dogs and cats, and the dose depends on weight and species. If one is needed, the vet says so, even over the phone.

6. 6

   Keep the animal under constant watch

   Even a reaction that started local can evolve. Stay with it, check breathing and gums, and be ready to leave for the clinic if anything changes in the hours that follow.

Among the stinging insects, bee, wasp and hornet, only the bee loses its stinger, which stays embedded in the skin together with the venom sac and keeps releasing venom until it is removed. Wasps and hornets do not leave it behind and can sting several times. That is why, faced with a bee sting, quick and correct removal of the stinger makes the difference to how much venom reaches the tissues.

• Scrape the stinger sideways, moving it parallel to the skin, with a fingernail or the edge of a stiff card.
• Do not grab it with your fingers or with tweezers squeezing from above: the pressure empties the sac and injects more venom.
• Act fast but calmly, because how long it stays in matters more than perfect technique.
• After removal apply cold to the area and keep watching for general signs.

The pine processionary is not a stinging insect but a caterpillar covered in urticating hairs that, at certain times of year, comes down from the trees and moves in a line across lawns and paths. No bite is needed: contact alone is enough. A curious dog sniffs or licks it, and the hairs release a strongly irritant substance capable of causing necrosis of the tissues it touches. The tongue is the most affected and most dangerous target.

• Sudden, very heavy drooling, often the first sign.
• Mouth pain, with the animal rubbing its face and refusing food.
• A swollen, reddened tongue, with areas that can turn whitish and go into necrosis.
• In severe cases, parts of the tongue can be lost permanently.

Not every bite comes from a winged insect. Spider bites are rare and in most cases cause only a local reaction, but some species can produce more important signs that appear even hours later: that is why a suspicious bite with intense pain or general signs should always be assessed by the vet, without trying to identify the spider and putting yourself at risk.

There are then two situations that are dangerous for mechanical reasons, regardless of allergy. The first is a sting inside the mouth or throat: the swelling that follows can narrow the airway and make breathing hard, so it should be treated as an emergency even in an animal that is not allergic. The second is multiple stings, typical of an animal that disturbs a nest or a swarm: the combined venom of many stings can trigger severe effects even in a subject that would not have reacted to a single one.

The practical rule is simple: a reaction that stays local and does not worsen is observed at home while staying in touch with the vet; any sign that reaches beyond the sting site means the clinic, straight away. This table sums up the situations that allow no waiting.

When the picture stays local, observing at home is reasonable, but it is not passive: it means checking breathing and gums, measuring the swelling over time, and keeping the clinic's number ready. When in doubt, a phone call to the vet or to a reference centre clarifies whether it is worth moving. A trip to the clinic that turns out to be unnecessary is always better than a wait that becomes too long.