Leptospirosis in dogs is treated with a combination of antibiotics and supportive hospital care, typically involving IV fluids and medications to protect the kidneys and liver. With aggressive treatment, about 73% of dogs survive, based on 2024 surveillance data from New York City. The speed of diagnosis and how quickly treatment begins play a major role in outcome.
How Leptospirosis Is Diagnosed
Before treatment starts, your vet needs to confirm the infection. The reference standard is a blood test called the microscopic agglutination test (MAT), which measures antibody levels against the bacteria. A single very high result (a titer of 1,600 or above) suggests recent infection, but the most reliable approach uses paired samples taken two to six weeks apart. A fourfold rise in antibody levels between the two samples confirms an active infection.
One complication with this test: vaccinated dogs can show low-level positive results that have nothing to do with active disease. Titers of 800 or below often reflect past infection or a recent vaccine rather than current illness. Your vet may also run a PCR test on blood or urine, which detects the bacteria’s genetic material directly and can provide faster results in the early stage of illness. Bloodwork checking kidney and liver values is typically done at the same time, since these organs are the primary targets of the infection.
The Two-Phase Antibiotic Approach
Treatment uses antibiotics in two phases because leptospira bacteria hide in different parts of the body at different stages. The first phase targets the bacteria circulating in the bloodstream. Dogs that are vomiting or too sick to take pills often start on an injectable penicillin-type antibiotic in the hospital.
The second, and arguably more important, phase clears the bacteria from the kidneys, where they can persist and continue shedding in urine for weeks or months. The standard protocol is a two-week course of doxycycline, given by mouth twice daily. This step is critical even if your dog seems to be feeling better, because without it, your dog can become a long-term carrier that sheds infectious bacteria in its urine. Dogs that can’t tolerate doxycycline (some experience nausea or vomiting on it) can be switched to alternative antibiotics to address the carrier phase.
Completing the full two weeks of doxycycline is non-negotiable. Stopping early risks leaving bacteria in the kidneys, which endangers both your dog and anyone in the household.
What Happens During Hospitalization
Most dogs with leptospirosis need to be hospitalized, at least initially. The infection commonly damages the kidneys, the liver, or both, and the body needs aggressive support while the antibiotics work.
IV fluid therapy is the backbone of supportive care. It helps maintain blood flow to the kidneys, correct dehydration, and restore electrolyte balance that gets thrown off when the kidneys aren’t functioning properly. Beyond fluids, your dog may receive medications to control nausea, manage pain, protect the stomach lining, support blood pressure, and provide nutrition if they’re not eating on their own.
In severe cases where the kidneys are badly damaged and not responding to standard fluid therapy, dialysis (hemodialysis or a related procedure) may be recommended. Not every veterinary hospital offers this, and it can be expensive, but for dogs with severe acute kidney injury that isn’t improving with conventional treatment, it can be lifesaving. Your vet will discuss this option if your dog’s kidney values aren’t trending in the right direction.
Hospital stays vary widely. Some dogs stabilize within a few days, while others with significant organ damage may need a week or more of intensive care.
Survival Rates and What Affects Them
NYC Health Department surveillance data from 2024 found that 73% of dogs with confirmed leptospirosis survived, while 27% died or were euthanized. These numbers reflect real-world outcomes across a range of severity levels.
Dogs diagnosed early, before severe kidney or liver failure sets in, have a much better chance. Dogs that develop complications like acute kidney failure requiring dialysis, severe liver dysfunction, or bleeding into the lungs face a harder road. Age, overall health, and the specific strain of leptospira involved also influence prognosis. If your dog pulls through the acute phase, many recover good kidney and liver function over time, though some are left with chronic kidney disease that needs ongoing management.
Protecting Yourself During Treatment
Leptospirosis spreads from dogs to humans, primarily through contact with infected urine. While your dog is being treated and for several weeks after, you need to take precautions seriously.
- Wear gloves when cleaning up urine, handling soiled bedding, or touching anything that may have been contaminated.
- Cover any open wounds with waterproof bandages before handling your dog or cleaning up after them.
- Wash your hands thoroughly after any contact with your dog or materials that could carry urine.
- Disinfect contaminated surfaces with antibacterial cleaner or a solution of one part household bleach to ten parts water.
Have your dog urinate away from areas where children play or other pets spend time. The bacteria survive well in warm, moist environments but are easily killed by drying, sunlight, and bleach solutions.
Recovery and Follow-Up After Discharge
Once your dog is eating, drinking, and stable enough to go home, the focus shifts to completing the full antibiotic course and monitoring organ function. Your vet will schedule follow-up bloodwork to track kidney and liver values as they (hopefully) return toward normal. How quickly these values improve gives your vet a picture of whether there’s lasting organ damage.
During recovery at home, keep your dog well-hydrated and watch for signs of relapse: loss of appetite, vomiting, increased thirst and urination, or lethargy. Some dogs with residual kidney damage will need a modified diet or ongoing monitoring for months afterward.
Preventing Future Infection
A leptospirosis vaccine is available that covers the four most common disease-causing strains. An expert panel convened by the American Veterinary Medical Association now recommends that all dogs receive this vaccine annually, rather than every three years, reflecting the understanding that virtually every dog faces some level of risk. Dogs that spend time outdoors, drink from puddles or natural water sources, or live in areas with wildlife are at particularly high risk, but urban dogs get leptospirosis too.
The vaccine doesn’t guarantee complete protection, and it doesn’t cover every strain of the bacteria. But vaccinated dogs that do get infected tend to have milder illness. If your dog has recovered from leptospirosis, vaccination is still recommended going forward, since infection with one strain doesn’t provide broad immunity against others.