A pet health guide for Costa Rica.

The cane toad is native and very common in gardens after dark and throughout the rainy season. Its parotoid glands, behind the eyes, release a milky toxin that affects the heart and nervous system. A dog does not need to eat the toad — simply mouthing or licking one is enough, and an untreated dog can die within about fifteen minutes.

A large, heavy, warty toad with two prominent oval glands behind the eyes. Often found near outdoor lights, water bowls, and pet food left out at night.

Screwworm re-emerged in Costa Rica in 2023 and is a reportable disease. Unlike ordinary maggots, these larvae feed on LIVING tissue, burrowing deeper into a wound hour by hour. Any open wound, however small, can be affected.

The adult is a metallic blue-green fly with orange eyes. In the wound you will see cream-coloured maggots burrowing head-first, packed tightly together, with the wound enlarging rather than healing and giving off a distinctive foul smell.

The brown dog tick is extremely common in Costa Rica and transmits Ehrlichia canis, a blood-borne infection that can quietly damage the immune system and platelets for weeks before symptoms appear.

A flat, reddish-brown, eight-legged tick, becoming grey and bean-shaped once engorged. Look in the ears, between the toes, in the groin, and around the neck. This species can also infest the house itself — cracks, bedding, and skirting boards.

Heartworm is spread by mosquitoes, which means the risk on the coast is year-round. Adult worms live in the heart and lungs. Prevention is simple, safe, and inexpensive; treatment of an established infection is long, costly, and risky. Prevention is by far the better path.

There is nothing to see externally — heartworm is found by a blood test. Any dog living near the coast without continuous prevention should be considered at risk.

The fer-de-lance, known locally as terciopelo, causes the most serious snakebites in Guanacaste. Dogs are usually bitten on the face or front legs while investigating. The venom destroys tissue and prevents blood from clotting; time to treatment is everything.

You may not see the snake. Suspect a bite if there is rapid, dramatic swelling — often with two puncture marks — that worsens by the minute, usually on the muzzle, head, or a leg.

Guanacaste heat is unforgiving. Dogs cool themselves mainly by panting, and once their body temperature climbs past a certain point, organs begin to fail. Flat-faced breeds, overweight, dark-coated, and senior animals are at highest risk — and a parked car becomes lethal in minutes.

Frantic, noisy panting that does not settle in the shade, with a bright red tongue and gums, and hot, dry skin. The animal may seem confused or unsteady.

Common household poisons include chocolate, xylitol (in sugar-free gum and peanut butter), rat poison, human medications such as ibuprofen and paracetamol, and garden plants. Rat poison is especially dangerous because signs may not appear for several days, by which time internal bleeding is advanced.

Look for chewed packaging, spilled pellets, or a raided bin. Xylitol and rat poison are dangerous in very small amounts; dark chocolate far more so than milk.

Fleas breed year-round here. Many pets are also allergic to flea saliva, so a single bite can trigger weeks of intense itching, hair loss, and secondary skin infection.

Part the coat at the base of the tail and on the belly. Look for fast-moving dark insects and 'flea dirt' — black specks that turn rusty red on a damp tissue.

Roundworms, hookworms, and tapeworms are widespread in tropical soil and are picked up from ground, prey, and fleas. Hookworm in particular can cause dangerous anaemia in young animals. Several of these worms can also infect people.

Look at the stool: spaghetti-like roundworms, or small rice-grain tapeworm segments around the anus and bedding. Hookworm is usually invisible and diagnosed by a faecal test.

Mange is caused by microscopic mites. Sarcoptic mange is intensely itchy, highly contagious between dogs, and can cause a temporary rash in people. Demodectic mange is not contagious and appears when the immune system is young, stressed, or unwell.

Sarcoptic: frantic itching with crusting on ear margins, elbows, and belly. Demodectic: patchy hair loss, often around the eyes and muzzle, with little or no itch. Diagnosis is by skin scrape.

Ear mites are tiny parasites that live in the ear canal. They are extremely common — especially in kittens, puppies and young rescues — intensely itchy, and pass easily between animals sharing a home or a bed.

Look for dark, dry, crumbly wax deep in the ear that looks like coffee grounds. It is usually in both ears, and often more than one pet in the house is scratching.

Ticks in Costa Rica carry blood infections — ehrlichiosis, anaplasmosis and babesiosis — that quietly damage blood cells and organs. A dog can look completely normal for weeks while the infection takes hold.

There is nothing to see on the outside. Suspect it in any dog that has had ticks and then becomes tired, feverish or off food. Diagnosis is a simple blood test.

A hot spot is a rapidly spreading, moist, infected patch of skin created by licking and scratching. In this climate one can go from a small damp spot to a palm-sized wound in a single day.

A red, wet, painful area with matted hair around it, often warm to the touch and smelling faintly sour. Common on the cheek, neck, hip, and tail base.

Warm, humid air, beach swimming, and floppy ears combine to make ear infections very common here. Left alone they become painful and can damage the ear canal permanently.

Lift the ear flap: look for redness, brown or yellow discharge, and a sweet or yeasty smell. A head tilt or pain on touch suggests the infection is deeper.

Ringworm is a fungus, not a worm, and thrives in humidity. It spreads easily between cats, dogs, and people, so early treatment protects the whole household.

Circular or irregular patches of hair loss with flaky, grey-crusted skin, often on the face, ears, and paws. Usually only mildly itchy. Confirmed by fungal culture or microscopy.

Environmental allergens, fleas and sometimes food can all make an animal itch. Allergies are very common in the tropics, where pollens, moulds and fleas are present all year rather than for one season.

Look for itching that keeps coming back: licking or chewing the paws, red skin in the armpits and groin, and ear infections that clear up and then return.

Eyes deteriorate quickly. Sand, salt, grass seeds, scratches from play, and infection can all progress to a corneal ulcer within a day or two. Any eye that is closed, cloudy, or painful should be seen promptly.

Compare the two eyes in good light. Look for squinting, cloudiness, redness of the white, discharge, or a visible dent or film on the surface.

Many lumps are harmless — fatty lumps, cysts, insect-bite swellings — but some are not, and they can look identical from the outside. A quick needle sample usually gives an answer the same day.

Any lump that is new, or one you already know about that changes size, shape, firmness or colour, bleeds, or seems to bother your pet.

By middle age most dogs and cats have some degree of periodontal disease. Beyond bad breath, it is a source of constant pain and sends bacteria into the bloodstream, affecting the heart, liver, and kidneys.

Lift the lip: healthy gums are pink and smooth. Look for a yellow-brown crust at the gum line, red or receding gums, and any loose or broken teeth.

One episode of vomiting or soft stool in a bright, drinking, otherwise happy pet is usually minor. But some patterns signal obstruction, poisoning, or bloat, which are life-threatening within hours.

Judge the whole animal, not just the stool. A pet who still greets you, drinks, and rests comfortably is different from one who is flat, painful, or repeatedly retching without producing anything.

In bloat the stomach fills with gas and can twist on itself, cutting off its own blood supply. It is one of the few true 'minutes matter' emergencies in veterinary medicine, and it happens most often in deep-chested dogs.

A swollen, hard, drum-like belly with repeated retching that brings nothing up, in a dog who cannot settle.

Straining to urinate, going very often, or blood in the urine can mean infection, crystals or stones. In cats — especially male cats — a blocked bladder is life-threatening within hours and must never be left overnight.

Watch the litter box or the garden: repeated trips, long straining with little or nothing coming out, or pink-tinged urine.

The first six months shape a lifetime. In the tropics that means an early, consistent plan for vaccination, deworming, parasite prevention, nutrition, and gentle socialisation — all of which can be done calmly at home.

A thriving youngster is round but not pot-bellied, gaining weight weekly, playful in bursts, with clear eyes, clean ears, and a soft glossy coat.

Older animals rarely complain. Arthritis, kidney and thyroid disease, dental pain, and cognitive change all develop slowly, and are often mistaken for 'just getting old'. Twice-yearly exams with blood work catch most of it early, and home visits spare a stiff, anxious animal the journey.

Watch for changes in routine rather than dramatic symptoms: slower to rise, sleeping in a new place, drinking more, or hesitating at stairs.

Good nutrition and a healthy weight are the foundation of a long, comfortable life. Obesity is one of the most common problems we see, and it quietly shortens lifespan while making joints, breathing and heat tolerance worse.

Run your hands over the ribs: you should feel them easily with a light touch, and from above you should see a clear waist behind the ribcage.

Spaying and neutering prevents unwanted litters and reduces several real health risks — certain cancers, life-threatening womb infections such as pyometra, and the roaming that leads to fights, ticks and road accidents.

The right timing varies with species, breed, size and lifestyle, so it is worth a short conversation rather than a fixed rule.

Taking a pet abroad means health certificates, current vaccinations, screwworm declarations, and government endorsement — all within strict time windows. Done in the right order it is smooth; done late it is stressful and can cost you the flight.

Plan backwards from your flight date. Some steps must happen within days of departure, others months ahead, and the requirements differ by destination country and airline.