How to keep your pet safe from leptospirosis as cases rise in Chicago

CHICAGO (WGN) – After multiple cases of rat-borne leptospirosis were reported in Chicago, city officials are sounding the alarm. But how can residents make sure their pets stay safe amid the recent uptick?

On Tuesday, the Chicago Department of Public Health said six cases of leptospirosis have been reported so far this year, higher than the historic median of two per year.

Leptospirosis can affect people, pets and wild animals. The bacteria that cause leptospirosis are spread through the urine of infected animals and can contaminate water and soil, where they can survive for weeks or months.

In four of the six cases identified, symptoms began between July 16 and Aug. 28.

Health officials said those infected in July and August all reported either direct exposure to animal waste, particularly from rats, or indirect exposure to rodent waste through gardening and yard work.

Officials added that the recent cases have been clustered around the Logan Square and West Town areas.

Between 2015 and 2025, 28 cases of leptospirosis have been recorded in Chicago, officials said.

In the United States, about 100-150 cases of leptospirosis are reported each year.

Leptospirosis dangers in pets

While health officials offered a warning to residents about leptospirosis, some residents may be wondering how they can protect their pets, as the long-term impact of leptospirosis could be devastating.

Just like humans, pets and wild animals are at risk of contracting leptospirosis through contact with contaminated urine or body fluids of an infected animal or through contact with contaminated water or soil.

But unlike humans, animals are also at risk of getting leptospirosis through bite wounds or skin damage from other animals, eating infected body tissues or organs or being born to an infected mother.

While treatment for leptospirosis usually helps an animal recover, organ damage caused by leptospirosis can be permanent.

The greatest risk for household pets is in dogs. The American Veterinary Medical Association (AVMA) says leptospirosis in cats is rare and appears to be mild, though little is known about the disease in the species.

According to the AVMA, all dogs are at risk for leptospirosis, regardless of age, breed, lifestyle, geographic location or time of year.

While cats are not at the same risk as dogs, similar steps can be taken to avoid exposure for both animals.

How to keep your pet safe from leptospirosis

The first step dog owners should take to ensure the health of their pup is to get them vaccinated, as a vaccine to prevent leptospirosis in dogs is available in the United States.

The vaccine does not provide 100% protection, given that there are several strains of the bacteria that cause leptospirosis and the vaccine does not protect against all strains.

Because leptospirosis is potentially life-threatening for dogs, the AVMA recommends that all dogs be vaccinated, adding that the vaccines are no more likely to cause side effects than other common vaccines.

However, once your pup is vaccinated, the AVMA says dog and cat owners can take several steps to make sure their pets stay safe.

In order to reduce the chance of exposure, the AVMA says pet owners should avoid letting their animals drink from or swim in rivers, lakes, ponds, marshy areas, or slow-moving or stagnant water, as they can be a source of the bacteria that cause leptospirosis.

In addition to maintaining an awareness about the cleanliness of water around pets, the AVMA also urges pet owners to avoid letting their animals spend time around farm animals and wild rodents, including carcasses.

Lastly, the AVMA warns pet owners to avoid letting their pet run freely on rural properties, as there is an increased risk of contact with a contaminated water source or infected wild animal.

Leptospirosis symptoms in pets

According to the CDC, in animals, signs and symptoms of leptospirosis can vary widely and while some animals do not even show symptoms, others can experience organ failure or death.

In dogs, symptoms can vary depending on several factors, including the strain of bacteria, the location of exposure and how the dog’s immune system reacts.

The AVMA says some infected dogs may not show any signs of illness, or may show mild and transient signs of illness before recovering spontaneously.

For others, leptospirosis can lead to severe, life-threatening illness. Signs of the illness in dogs can be non-specific and may include fever, shivering, muscle tenderness, reluctance to move, increased thirst, changes in the frequency or amount of urination, dehydration, vomiting, diarrhea, loss of appetite, lethargy, jaundice, or painful inflammation within the eyes.

In dogs, leptospirosis can also cause bleeding disorders, which can lead to blood-tinged vomit, urine, feces or saliva as well as nosebleeds and pinpoint red spots.

Fluid accumulation can also lead to swollen legs in dogs or the buildup of excess fluid in their chest or abdomen.

Dogs who contract leptospirosis are also at risk of kidney failure with or without liver failure and severe lung disease.

Given that leptospirosis in cats is rare and often mild, visible symptoms are also rare, the CDC said.

Leptospirosis treatment in pets

The CDC urges anyone who feels their pet may have leptospirosis to contact a veterinarian immediately to confirm if they have it.

When treated early, the AVMA says recovery chances are good, but there is still a risk of permanent residual kidney or liver damage.

Generally, leptospirosis in pets is treated with antibiotics and supportive care; however, dogs with particularly severe cases may require fluid therapy and additional nutritional support.

The AVMA says in extreme cases, oxygen therapy, mechanical ventilation for breathing support, kidney dialysis or other intensive care measures may be necessary.

Additional dogs in the home may also require treatment even if they do not appear ill.