Leptospirosis in Animals

What is Leptospirosis?

Leptospirosis is a dangerous bacterial disease caused by Leptospira bacteria. It can affect almost all animals and humans. It is a zoonotic disease, meaning animals can spread it to people.

Commonly affected animals:

  • Cattle
  • Dogs
  • Horses
  • Sheep
  • Goats
  • Pigs
  • Rats
  • Cats (less common)

Types of Leptospirosis in Animals

Leptospirosis is caused by different serovars (types) of Leptospira bacteria. Different animal species are commonly affected by different serovars.

1. Leptospirosis in Cattle

Common serovars:

  • Hardjo
  • Pomona
  • Grippotyphosa
  • Icterohaemorrhagiae

Main problems

  • Abortion
  • Infertility
  • Decreased milk production
  • Fever
  • Kidney and liver damage

Cattle can become long-term carriers and shed bacteria in urine.

2. Leptospirosis in Dogs

Common serovars:

  • Canicola
  • Icterohaemorrhagiae
  • Pomona
  • Grippotyphosa
  • Bratislava

Main problems

  • High fever
  • Vomiting
  • Kidney failure
  • Liver disease
  • Bleeding disorders
  • Respiratory distress

Dogs are an important source of human infection.

3. Leptospirosis in Horses

Common serovars:

  • Pomona
  • Bratislava
  • Grippotyphosa

Main problems

  • Recurrent uveitis (moon blindness)
  • Abortion
  • Fever
  • Weakness
  • Kidney disease (rare)

4. Leptospirosis in Sheep and Goats

Common serovars:

  • Pomona
  • Hardjo
  • Grippotyphosa

Main problems

  • Abortion
  • Weak lambs/kids
  • Fever
  • Reduced fertility
  • Mild kidney disease

Many infections remain subclinical.

5. Leptospirosis in Pigs

Common serovars:

  • Pomona
  • Bratislava
  • Tarassovi

Main problems

  • Reproductive failure
  • Stillbirths
  • Mummified fetuses
  • Infertility

Pigs can shed bacteria in urine for long periods.

6. Leptospirosis in Cats

Common serovars:

  • Pomona
  • Bratislava
  • Grippotyphosa

Main problems

  • Usually mild or no signs
  • Fever
  • Kidney disease (rare)

Outdoor cats are at higher risk.

How does it spread?

The bacteria mainly spread through:

  • Urine of infected animals
  • Contaminated water
  • Wet soil or mud
  • Placenta, milk, or reproductive fluids

Animals become infected when bacteria enter through:

  • Mouth
  • Nose
  • Eyes
  • Broken skin

Rats and dogs are major sources of infection.

Where does the bacteria survive?

Leptospira survive best in:

  • Warm weather
  • Wet environments
  • Rainy areas
  • Standing water

They die quickly in:

  • Dry soil
  • Direct sunlight
  • Freezing temperatures

What organs are affected?

Mainly:

  • Kidneys
  • Liver
  • Lungs
  • Reproductive tract
  • Eyes
  • Brain/CNS

Clinical Signs (Symptoms)

General signs

  • Fever
  • Weakness
  • Loss of appetite
  • Depression
  • Muscle pain

Kidney signs

  • Increased urination
  • Dehydration
  • Kidney failure

Liver signs

  • Jaundice (yellow eyes/gums)
  • Liver damage

Respiratory signs

  • Difficulty breathing
  • Lung bleeding

Reproductive problems

  • Abortion
  • Stillbirth
  • Weak newborns

Many animals may show only mild signs or no signs at all.

How is it diagnosed?

1. MAT Test (Microscopic Agglutination Test)

Detects antibodies against Leptospira.

2. PCR Test

Detects the bacteria directly in:

  • Blood
  • Urine
  • Tissue

PCR + serology together give the best diagnosis.

Treatment

Antibiotics are usually effective if given early.

Commonly used antibiotics:

  • Penicillin
  • Doxycycline
  • Oxytetracycline

Supportive treatment may include:

  • IV fluids
  • Kidney support
  • Liver support

Severe organ damage may become permanent.

Prevention

Vaccination

Vaccines are the best prevention method in:

  • Dogs
  • Cattle
  • Pigs

Management

  • Control rats and rodents
  • Avoid stagnant water
  • Keep animal housing clean
  • Isolate infected animals

Zoonotic Risk (Risk to Humans)

Humans can get infected through:

  • Urine
  • Blood
  • Contaminated water

People at higher risk:

  • Veterinarians
  • Farmers
  • Dairy workers
  • Animal handlers

Human symptoms

  • Fever
  • Headache
  • Muscle pain
  • Red eyes
  • Weakness
  • Kidney or liver failure in severe cases

Pregnant women should avoid exposure because infection can harm the baby.

Safety Precautions

When handling suspected animals:

  • Wear gloves
  • Use boots and gowns
  • Wash hands properly
  • Avoid contact with urine
  • Use face protection during cleaning

Key Points

  • Leptospirosis is spread mainly through infected urine.
  • Rats are important carriers.
  • Kidneys and liver are commonly damaged.
  • It can cause abortion in pregnant animals.
  • Disease can spread from animals to humans.
  • Vaccination and hygiene are very important.

Reference

This content has been written after reviewing the clinical knowledge and professional experiences of Katharine F. Lunn, Department of Clinical Sciences, College of Veterinary Medicine, North Carolina State University, as published on the MSD Veterinary Manual. As a veterinary doctor, I have carefully studied and summarized these expert-reviewed findings for educational and professional veterinary purposes.