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Key takeaways

Plague is an infection caused by Yersinia pestis, a species of bacteria found in wild rodent populations. 

  • Dogs become infected with the bacteria through the bite of an infected flea, or through ingesting an infected rodent
  • Dogs are considered naturally resistant to infection, and often develop mild or no symptoms
  • When present, symptoms include fever, lethargy, enlarged lymph nodes, and coughing
  • Diagnosis involves a physical examination, bloodwork, and bacterial culture
  • Treatment is with antibiotics
  • Infected dogs require quarantine away from other animals and people, as the disease is highly infectious
  • Most cases in dogs have a good prognosis with treatment
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A closer look: Plague in Dogs

Dogs are considered naturally resistant to infection by Yersinia pestis. Bloodwork in endemic areas shows 2% of dogs have signs of exposure, while cases of symptomatic illness remain very rare. Plague is highly infectious to people, however, who may acquire the infection from an infected dog. Dogs that show symptoms of plague require immediate veterinary attention, primarily so that proper biosecurity measures can be put in place to reduce the spread of disease to other animals, including humans.

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Risk factors

The incidence of plague varies by geographic location. Asia, Africa, North America, and South America are where it most commonly occurs. Most cases in North America occur in the Southwestern US and California. Europe, Australia, and Japan report no cases of plague.

In some cases, dogs may develop the bubonic form of plague, resulting in enlarged lymph nodes that rupture and release large amounts of pus. Lymph nodes around the head and neck are most commonly affected in these cases.

Dogs that may be exposed to rodents and fleas are at highest risk of exposure in endemic areas.

Possible causes

The bacteria Yersinia pestis is the causative agent of plague. Rodents are the primary carrier of this bacteria, including ground squirrels, prairie dogs, and rabbits. Fleas feed on these species, then may transfer the bacteria to other animals. Dogs become infected either through the bite of an infected flea, or ingestion of an infected rodent.

Main symptoms

Dogs are considered naturally resistant to plague, and often do not develop any symptoms.

Testing and diagnosis

Diagnosis focuses on confirming plague as the cause of symptoms. Diagnostic tests include:

  • Physical examination
  • Bloodwork
  • Testing of the blood or tissues for Yersinia pestis
  • Bacterial culture

Steps to Recovery

Treatment primarily involves a course of antibiotics designed to eliminate the bacterial infection. Affected dogs also require flea treatment, as that is the most common source of infection. Abscesses occurring in cases of the bubonic form are lanced and flushed.

During treatment, dogs require hospitalization under quarantine to prevent spread of the disease to humans, including pet owners. Dogs infected with the bacteria must be handled with appropriate protective equipment, such as masks and gloves, to prevent human infection.

Most dogs with plague develop only mild or no symptoms, and recover rapidly with treatment. Treatment typically takes 10-21 days to ensure that the infection is completely cleared, however symptoms often resolve within several days of beginning therapy.


Plague can be prevented by reducing exposure to rodents and fleas. Routine flea control medications can reduce the risk of flea exposure. Note: always consult a veterinarian before choosing external parasite control. Many available products are toxic to pets, especially cats.

Storing food in rodent-proof containers, reducing rodent habitats near homes and in gardens, and keeping dogs on a leash when walking in areas known to house rodents are effective preventive measures.

Following all quarantine and biosecurity measures during treatment of diagnosed dogs helps prevent the spread of infection to other animals, including humans.

Is Plague in Dogs common?

Plague is rare in dogs, but more common in the Southwestern US and California.

Typical Treatment

  • Antibiotics
  • Quarantine


Paul Ettestad, DVM, MS - Writing for Merck Veterinary Manual
Jennifer A. House, DVM, MPH, DACVPM - Writing for Merck Veterinary Manual

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