강아지 렙토스피라 신장 침범 증상과 원인, 진단·치료와 관리 포인트 총정리

Lethargy and Vomiting in Dogs — Signs of Leptospiral Kidney Involvement and When to Visit the Vet

KidneyDiseasesMeongsiljang Veterinary Advisory Board

Leptospiral kidney involvement in dogs is a condition where infection with Leptospira bacteria leads to kidney damage, with increased water intake and frequent urination being the main symptoms. Early diagnosis and appropriate treatment are essential.

What is Leptospiral Kidney Involvement in Dogs?

A scene of a puppy drinking from contaminated water, an environment with Leptospira bacteria

Leptospirosis affecting the kidneys in dogs is a disease caused by infection with Leptospira bacteria, leading to kidney inflammation and impaired function. These bacteria enter a dog’s body through contaminated water or soil, spread via the bloodstream, and colonize the renal tubules, causing acute kidney injury and interstitial nephritis. Dogs that frequently play in environments with standing water after rain, or near streams and ponds, are at higher risk of exposure. After infection, the bacteria typically circulate in the blood for a short period of about a week, and symptoms may begin to appear around 10 days as the bacteria invade kidney tissue. Initial symptoms may be mild but can worsen rapidly, making early diagnosis and appropriate treatment crucial for improving survival rates. When kidney function is compromised, the body struggles to regulate fluids and eliminate waste products, which can lead to a rapid decline in overall health.

What are the Causes and Routes of Infection?

Leptospirosis affecting the kidneys in dogs is caused by infection with Leptospira bacteria. These bacteria primarily contaminate water and soil through the urine of rodents such as mice or wild animals. Dogs can become infected when they come into contact with or drink contaminated water or soil. The risk of exposure is especially high for dogs that frequently play near rivers, ponds, or standing water after rainfall. Once infected, the bacteria spread through the bloodstream, circulating in the blood for about a week before moving to the renal tubules and beginning to be excreted in the urine. Because this process can damage the kidneys, early diagnosis and treatment are crucial if you notice any suspicious symptoms.

Microscopic image of Leptospira bacteria confirmed in a urine test

What are the Main Symptoms and Signs?

The main symptoms of leptospiral kidney involvement in dogs are as follows. These symptoms arise due to decreased kidney function and a systemic inflammatory response.

Excessive thirst: There is a sudden increase in the frequency of drinking water.

Frequent urination and increased urine volume: The dog urinates multiple times a day, with a larger volume of urine each time.

Vomiting and loss of appetite: As gastrointestinal function declines, appetite decreases and vomiting becomes recurrent.

Fatigue and lethargy: The dog remains inactive and weak for extended periods throughout the day.

Jaundice: The eyes or lips turn yellow, indicating possible liver dysfunction.

If any of these symptoms appear, consult a veterinarian immediately.

A lethargic puppy suffering from leptospira infection

Symptoms Requiring Immediate Veterinary Care

If your dog experiences repeated vomiting, is unable to urinate at all, or suddenly becomes lethargic with clouded consciousness, immediate veterinary care is necessary. These symptoms may indicate a rapid decline in kidney function, which can be life-threatening. Additionally, leptospirosis can be transmitted to humans, so exercise caution when handling an infected dog.

How is it Diagnosed?

Leptospiral kidney involvement in dogs is accurately diagnosed through a combination of tests. First, blood tests are used to assess kidney function by checking for elevated creatinine and BUN levels. Urinalysis is performed to look for the presence of protein, inflammatory cells, and white blood cells. Additionally, serological tests or PCR testing are conducted to detect leptospiral antibodies or genetic material, confirming infection. If necessary, renal ultrasound is used to evaluate changes in kidney size or structural abnormalities. Multiple tests are performed together to ensure an accurate diagnosis.

Ultrasound-confirmed enlarged and structurally irregular kidneys in a dog

Treatment Methods and Step-by-Step Management

Treatment for leptospiral kidney involvement in dogs consists of antibiotics, fluid therapy, and symptomatic relief. First, intravenous fluids are administered to address dehydration based on the dog’s condition, and antibiotics (such as doxycycline) are given to eliminate the bacteria. If kidney function is impaired, a special diet should be introduced to reduce the burden on the kidneys. The typical treatment duration is 2 to 4 weeks, and regular check-ups are necessary after recovery to monitor for recurrence.

A veterinarian administering an intravenous injection to a puppy infected with leptospirosis.

Home Care Points

Home care is crucial after your dog’s kidneys have been affected by leptospirosis. During treatment, provide the prescription diet or food plan recommended by your veterinarian to reduce kidney strain, and always ensure fresh water is readily available. Administer medications exactly as directed by your vet, and do not stop them prematurely even if symptoms improve. Since leptospira bacteria can spread to humans and other animals, always disinfect and properly dispose of your infected dog’s feces and urine, wearing gloves and washing your hands thoroughly afterward. Minimize contact with other animals, and keep up with regular veterinary visits to monitor kidney function and treatment progress.

A puppy undergoing leptospira treatment eating special kidney food

Preventing Recurrence and Breed Considerations

Even after recovery, dogs can be reinfected with Leptospira upon re-exposure, so it’s important to keep up with regular vaccinations. Dogs living in rural areas or near rivers and wetlands, as well as those with frequent contact with rodents or wildlife, are at higher risk of exposure and are strongly recommended to receive the vaccine. However, even vaccinated dogs can become infected and shed the bacteria in their urine, so don’t rely solely on vaccination—also minimize contact with potentially contaminated water or environments. Additionally, some dogs may develop chronic kidney disease after recovery, so regular kidney function tests are essential for ongoing health management.

Reviewed by a veterinarian

Dr. Tony — Punnawat Phongkittirak

Veterinarian

A veterinarian who majored in veterinary medicine at Khon Kaen University, Thailand, and completed the IVSA program at North Carolina State University in the United States. Drawing on clinical experience at animal hospitals, he works in the pet healthcare field and is dedicated to building a digital care environment that connects pet parents with veterinarians.

Frequently Asked Questions

Can leptospira infection be transmitted to humans?

Yes, leptospirosis can be transmitted to humans. There is a risk of infection if you come into contact with the urine or feces of an infected dog, so it is essential to wash your hands thoroughly and disinfect the area.

When should I start vaccinating my pet?

Puppies typically begin their vaccination series around eight weeks of age, followed by at least two primary doses spaced several weeks apart, with an annual booster thereafter. However, since vaccination may not completely prevent infection or shedding of pathogens, please consult your veterinarian to determine the most appropriate schedule for your dog.

Will kidney function recover after the infection?

With early treatment, many dogs can recover kidney function, but some may develop chronic kidney disease. Regular check-ups are essential to manage their condition.

Can leptospirosis still be transmitted after treatment?

Even after treatment, bacteria can remain in the urine for several weeks to months, maintaining its infectious potential. Therefore, it is important to avoid contact with other animals for a while after recovery and to be especially careful with disinfection and handwashing when handling urine.

What should you do if you suspect your dog has leptospirosis at home?

If your pet shows symptoms such as excessive thirst, frequent urination, vomiting, or lethargy, consult a veterinarian immediately. Early diagnosis and treatment can significantly improve survival rates.

Step-by-Step Symptoms and Management of Leptospira Infection

Item	Main symptoms	Treatment direction	Prognosis
Mild	Intermittent vomiting, slightly increased thirst	Oral antibiotics, fluid supplementation	Good
Moderate	Persistent vomiting, polyuria, lethargy	Intravenous injection, potent antibiotics	Fair
Severe	No urine, decreased consciousness, jaundice	Intensive care, fluid therapy, renal support treatment	Uncertain

Because the treatment method and prognosis vary with the severity of symptoms, early detection is important.

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References

[1] Plumb's Veterinary Drug Handbook, 9th Edition, 2022

[2] The Merck Veterinary Manual, 12th Edition, 2021

[3] Small Animal Internal Medicine, 5th Edition, 2020