Flood water carries Leptospira, the bacteria behind rat fever, and dogs catch it as easily as people do. Here is how dogs are exposed, the signs to watch for, and how yearly vaccination and a few habits protect them.
Every monsoon, flood water moves through gardens, lanes and drains across Sri Lanka. One of the things it carries is Leptospira, the bacteria behind leptospirosis, known locally as "rat fever". Leptospirosis affects dogs as well as people, it can be serious, and it is largely preventable. Here is what every dog owner should know before the next heavy rain.
How Dogs Catch Leptospirosis
The bacteria are shed in the urine of infected animals, most often rats, but also cattle, other dogs and wildlife. They survive for weeks in warm, wet soil and still or slow-moving water. Dogs become infected when that water or mud contacts their mouth, eyes, nose or broken skin, usually by drinking from puddles, wading through flood water, or licking wet paws afterwards. The risk rises sharply in the weeks after flooding, when contaminated water spreads well beyond the drains.
Signs to Watch For
Symptoms usually appear between a few days and two weeks after exposure. They vary widely, and some dogs show only mild illness. Common signs include:
- Fever, shivering or unusual lethargy
- Loss of appetite, vomiting or diarrhoea
- Muscle pain or reluctance to move
- Drinking and urinating noticeably more, or much less, than usual
- Yellowing of the gums, eyes or skin (jaundice)
- Red spots on the gums, or bleeding
Leptospirosis can damage the kidneys and liver. Early treatment with antibiotics greatly improves the outcome, so if your dog has been near flood water and seems unwell, see a vet that day and tell them about the exposure.
Vaccination Is the Main Protection
Most routine dog vaccine combinations used in Sri Lanka include leptospirosis (often shown as the "L" in the vaccine name). Protection against leptospirosis is shorter-lived than for some other vaccines, so it generally needs a booster every year. If you are not sure when your dog was last vaccinated, check their vaccination card or ask your vet before the rains peak, not after.
Vaccination greatly reduces the risk of serious disease, but no vaccine covers every strain, so avoiding exposure still matters.
Reducing Exposure During the Rains
- Avoid walks through flood water and stagnant puddles wherever possible.
- Carry clean water on walks so your dog is not tempted to drink from the ground.
- Rinse and dry paws after walking through wet areas.
- Keep food stored securely so it does not attract rats to your home.
- Keep water and food bowls indoors or covered, and wash them daily.
Protecting Your Family Too
Leptospirosis can pass from animals to people. If your dog is diagnosed, wear gloves when cleaning up urine, wash your hands well, and follow your vet's guidance until treatment is complete. Anyone in the household who develops fever or muscle aches should mention the dog's diagnosis to their doctor.
Frequently Asked Questions
My dog is vaccinated. Can they still get leptospirosis? It is much less likely, and illness is usually milder, but not impossible, because there are many strains of the bacteria. Keep reducing exposure during flood periods.
Is it only a problem in rural areas? No. Urban drains and low-lying streets in Colombo and other cities flood regularly, and rats are common in towns. Urban dogs are very much at risk.
How is it diagnosed? Your vet will usually use blood and urine tests. Tell them about any flood or puddle exposure, because that history helps them decide quickly.