Sandflies in Spain: The Bug That Can Kill Your Dog (2026)

Every summer, Spanish vets see the same heartbreaking pattern: an expat family’s dog, healthy on arrival, slowly develops skin sores, loses weight and turns out to have canine leishmaniasis — a disease their new country is riddled with, spread by an insect most newcomers have never heard of. That insect is the sandfly, and mid-July is exactly when it’s biting hardest.

If you own a dog in Spain — or you’re planning to move here with one — this is arguably the single most important pest article on this site. Mosquitoes are a nuisance; the sandfly can be a killer. Here’s what it is, why it matters far more than its size suggests, and the layered protection that actually works.

What Exactly Is a Sandfly?

A sandfly (flebotomo in Spanish) is not a fly and not quite a mosquito. It’s a tiny, sand-coloured biting insect just 2–3 millimetres long — small enough to pass through ordinary mosquito netting, and almost completely silent, so you won’t hear the tell-tale whine that warns you a mosquito is near.

Key facts that make it dangerous:

• It bites at night. Sandflies are active from dusk until dawn, peaking in the warm hours after sunset.
• It’s a weak flier. It doesn’t travel far or high, so it bites close to the ground — right where a dog sleeps.
• It breeds in dark, humid muck. Leaf litter, wall cracks, drains, compost, animal shelters and undisturbed corners of the garden are its nurseries.
• Only the female bites, taking blood to develop her eggs — and it’s that blood meal that transmits the parasite.

Because it’s so small and silent, most people never realise they or their pets are being bitten at all.

Why the Sandfly Matters So Much: Canine Leishmaniasis

The sandfly’s bite is usually harmless in itself. The danger is what it can carry: a microscopic parasite called Leishmania infantum, the cause of canine leishmaniasis (in Spanish, leishmaniosis canina).

Spain is one of the most affected countries in Europe. Across the country, the share of dogs that test positive ranges from around 5% in lower-risk zones to over 30% in the hottest southern and eastern regions. The parasite lives in a cycle between dogs and sandflies — a sandfly bites an infected dog, picks up the parasite, then injects it into the next dog it bites.

Once inside the dog, the parasite can spread over months or even years, quietly damaging the skin, kidneys, joints, eyes and internal organs. Many dogs carry it silently before symptoms ever appear — which is why prevention and early testing beat waiting for signs.

The Regions Where Risk Is Highest

Sandflies thrive in warm, low-lying, humid areas, which maps neatly onto the parts of Spain where most expats settle:

• Coastal Andalusia — Málaga, the Costa del Sol, Granada, Almería
• Region of Murcia and the Costa Cálida
• Valencian Community — Alicante, the Costa Blanca, Valencia
• Catalonia and the coast around Barcelona
• Balearic Islands — Mallorca, Ibiza, Menorca
• Extremadura and inland Madrid

Higher altitude and cooler, drier northern regions (much of Galicia, Asturias, the Basque Country) have historically been lower-risk — but as our guide to climate change and pests in Spain explains, warming temperatures are steadily pushing sandflies further north and to higher ground each year.

How to Know If Your Dog Is at Risk

Early leishmaniasis is a master of disguise. Signs can appear months after the bite and are easy to blame on something else. See your vet for a blood test if you notice a combination of:

• Skin problems — hair loss and flaky, dandruff-like skin around the eyes (“spectacle” pattern), ears and muzzle
• Slow-healing sores or ulcers, often on the nose, ear tips or pressure points
• Overgrown, brittle claws that seem to grow abnormally fast
• Weight loss despite a normal or even increased appetite
• Tiredness, reluctance to exercise, and swollen lymph nodes
• Nosebleeds
• Increased thirst and urination — a warning sign of kidney damage

The Three-Layer Protection Plan

No single product is bulletproof, so the veterinary consensus in Spain is to layer your defences. Do all three and you dramatically cut the odds.

Layer 2 — Control the exposure. Keep your dog indoors from dusk to dawn, when sandflies bite. Fit fine-mesh insect screens on windows and doors (standard mosquito mesh may be too coarse — look for sandfly-grade fine netting). Avoid leaving your dog to sleep outdoors in summer, especially near gardens, drains, compost or animal enclosures where sandflies breed.

Layer 3 — Vaccinate and test. Ask your vet about the canine leishmaniasis vaccine, which reduces the chance that an infected bite develops into disease. Pair it with an annual blood test so any infection is caught at the earliest, most treatable stage. In high-risk regions, this yearly check is one of the most valuable things you can do for a dog’s long-term health.

Sandflies and People: Should You Worry?

Sandflies do bite humans, and the same parasite can infect people — but for healthy adults the risk is low. The usual result is cutaneous leishmaniasis: a slow-healing skin sore that eventually resolves, sometimes leaving a small scar. Serious internal (visceral) disease is rare and overwhelmingly affects people with weakened immune systems, such as those on immunosuppressive treatment.

You cannot catch leishmaniasis from your dog directly — only an infected sandfly transmits it. Reassuringly, the same habits that protect your pet protect you: screens on the windows, covering up at dusk, and a good insect repellent (DEET or icaridin) on exposed skin during summer evenings.

The Bottom Line

The sandfly is the smallest pest we cover on this site and, for dog owners, one of the most dangerous. It’s silent, it bites at night close to the ground, and it can carry a disease that Spain sees more of than almost anywhere in Europe. But the response is refreshingly practical: repel it, avoid it, and vaccinate and test your dog — all three, every summer from May to October.

If your dog isn’t protected right now, in the peak of the season, treat it as this week’s priority. A collar or spot-on and a vet visit are cheap insurance against a disease that is anything but. And while you’re protecting your dog against summer parasites, don’t forget the other seasonal threats — our guides to ticks in Spain and mosquitoes in Spain round out the picture.

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Sources: Spanish veterinary and public-health guidance on canine leishmaniasis and sandfly (Phlebotomus) distribution; European seroprevalence surveillance for Leishmania infantum in dogs. This article is general information, not veterinary advice — consult your vet about the right prevention plan for your dog.