Leptospirosis in Dogs: What Every Pet Owner Should Know 

Leptospirosis is a disease we are diagnosing more frequently in our area, including here in our hospital and across Long Island. Because it can be serious—but also preventable—it’s important for pet owners to understand what it is, how it spreads, and how to protect their dogs. 

What Is Leptospirosis? 

Leptospirosis is a bacterial infection caused by Leptospira organisms. These bacteria thrive in warm, wet environments and can survive in soil and standing water for long periods of time. 

Dogs become infected when the bacteria enter the body through the mouth, nose, eyes, or small breaks in the skin. 

How Does It Spread? 

Leptospirosis is most commonly spread through contact with: 

• Contaminated water (puddles, ponds, lakes) 

• Wet soil 

• Urine from infected wildlife 
   

Wild animals such as rodents, raccoons, skunks, and deer are common carriers. This means that even dogs who never leave their yard can still be exposed if wildlife visits the area. 

What Happens When a Dog Gets Infected? 

Once inside the body, the bacteria travel through the bloodstream and can affect multiple organs—most notably the kidneys and liver. 

Leptospirosis can cause: 

• Kidney failure 

• Liver disease 

• Severe dehydration 

• Bleeding disorders 

• Lung involvement in severe cases 
   

In some cases, the disease can become life-threatening very quickly and require hospitalization. 

Signs to Watch For 

Symptoms can vary and may be subtle at first. Common signs include: 

• Lethargy 

• Loss of appetite 

• Vomiting and/or diarrhea 

• Increased thirst and urination 

• Fever 

• Muscle pain or stiffness 

• Yellowing of the eyes or gums (jaundice) 
   

If your dog is showing any of these signs, especially after possible exposure to standing water or wildlife, it is important to seek veterinary care right away. 

Why We’re Talking About This Now 

We are currently seeing an increase in leptospirosis cases, both in our hospital and throughout Long Island. Many of these patients are sick enough to require hospitalization and intensive care. 

This rise reinforces how common and serious this disease can be—even for dogs that don’t frequently travel or hike. 

The Risk to Humans (Zoonosis) 

Leptospirosis is a zoonotic disease, meaning it can be transmitted from animals to people. 

Humans can become infected through contact with contaminated urine or bodily fluids from an infected dog or from the same environmental sources. While transmission is not extremely common, it is a real concern—especially in households with children, elderly individuals, or immunocompromised family members. 

This is another important reason prevention is key. 

The Leptospirosis Vaccine 

The good news is that leptospirosis is preventable with vaccination. 

Vaccine Schedule: 

• Initial vaccine 

• Booster 3–4 weeks later 

• Then the annual vaccination 
   

This vaccine helps protect against the most common strains of the bacteria and significantly reduces the risk of severe disease. 

Why Vaccination Is Important 

Even if your dog: 

• Stays mostly in the yard 

• Doesn’t go hiking or swimming 

• Lives in a suburban neighborhood 
   

They are still at risk due to wildlife exposure and environmental contamination. 

Vaccination: 

• Protects your dog from serious illness 

• Reduces the risk of hospitalization 

• Helps protect your household from zoonotic transmission 
   

Final Thoughts 

Leptospirosis is a disease we are seeing more often, and it can become severe quickly. The combination of environmental exposure, wildlife presence, and increasing local cases makes prevention more important than ever. 

If you have questions about your dog’s risk or whether they are up to date on their leptospirosis vaccine, book an appointment with Levittown Animal Hospital. Our team is here to help ensure your canine friend stays playful and healthy throughout their life.

Prevention is simple—protection is powerful.