Listeria spp

From Dog
L. monocytogenes under electron microscopy[1]

Listeria spp are a Gram-positive, anaerobic zoonotic bacteria normally found in the gastrointestinal microbiota of dogs[2].

Although of relatively minor importance to dogs, these bacteria are found in 20% of dog fecal samples during routine serological surveys[3], where they contribute to zoonotic and environmental spread to humans, who are prone to consequently developing listeriosis from contaminated food.

Species which are pathogenic to dogs include:

  • Listeria monocytogenes

Few reports of illness have been reported with this bacteria apart from diarrhea and tonsillitis[4].

Systemic infections have also been recorded, with affected dogs developing neurological signs such as circling, hemiparesis and depression[5].

Diagnosis is based on clinical signs and histopathological testing of infected tissues. Postmortem findings usually show widespread multifocal inflammatory lesions in the lungs, liver, spleen, meninges, lymph nodes, adrenal glands and kidneys. Culture of the bacteria is usually definitive.

Treatment is based empirically on aggressive antimicrobial therapy with broad-spectrum drugs such as metronidazole, enrofloxacin or amoxycillin/clavulanate.


  1. Virginia Cooperative Extension
  2. Vaissaire J (2000) Epidemiology of animal Listeria infections in France. Bull Acad Natl Med 184(2):275-285
  3. Gicik Y et al (2010) The seropositivity of Toxoplasma gondii and Listeria monocytogenes in the dogs of Kars and vicinity. Turkiye Parazitol Derg 34(2):86-90
  4. Läikkö T et al (2004) Canine tonsillitis associated with Listeria monocytogenes. Vet Rec 154(23):732
  5. Schroeder H & van Rensburg IB (1993) Generalised Listeria monocytogenes infection in a dog. J S Afr Vet Assoc 64(3):133-136