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Salmonellosis - Infection with Salmonella Bacteria

Signs, Symptoms and Prevention of this Zoonotic Disease


Salmonella typhimurium bacteria

Colorized scanning electron micrograph (SEM) at 8000X revealed the presence of a small grouping of Gram-negative Salmonella typhimurium bacteria that had been isolated from a pure culture.

CDC/Janice Haney Carr

Salmonella is a genus of bacteria that is normally found in the intestines of both cold- and warm-blooded animals and in the environment. Learn how this bacteria causes disease in humans and animals, what the symptoms are, and how to prevent infection and spread of this disease.

Note: This article is focused on Salmonellosis in dogs and cats and veterinary health as a zoonotic disease; one transmissible from animals to humans. Please visit the Centers for Disease Control (CD) for more information on human Salmonellosis.

Salmonella Sources

Salmonella is named after Daniel Elmer Salmon, the first veterinary student to graduate with a DVM degree in the US, from Cornell University in 1876. From the Cornell history archives:

"...Salmon earned the first DVM degree in the country. Dr. Salmon went on to serve as the founding chief of the US Bureau of Animal Industry and is best known today for identifying the infectious pathogen Salmonella and pioneering the fight against contagious diseases."

Salmonella bacteria live in the intestines of animals and birds. Contamination of foods, eating surfaces and hands with fecal matter is how Salmonella is spread and has the potential to cause illness.

There are many strains of Salmonella bacteria. According to the USDA, the Salmonella family includes over 2,300 serotypes of bacteria, but only a few of those strains cause illness. Some strains cause illness in people and not in animals and vice versa.

Potential sources for Salmonella infection (called Salmonellosis) include:

  • Caring for sick pets, particularly dogs and cats that have diarrhea
  • Birds and reptile pets that are handled without proper sanitation afterward (e.g. hand washing with soap) -- animals and environment may be contaminated without illness in the animals
  • Pet foods - both raw foods and commercial pet foods may be potentially contaminated with salmonella
  • Human foods - improperly cooked or handled, raw foods such as salads
  • Hands not properly washed

Who is At Risk

Infection by Salmonella bacteria is somewhat dose-dependent (amount of bacteria consumed) and strain-dependent, but both pets and people are susceptible to infectious strains of Salmonella.

Those particularly at risk are the young, elderly, and pregnant or immunocompromised patients - e.g. those with cancer or immunosuppressive diseases (viral origin, diabetes, etc.).

It is important to note that some pets will not have any signs, but could potentially pass on Salmonella to humans. Also, people may become infected by handling contaminated pet food.

Symptoms of Salmonellosis

Symptoms of Salmonella infection typically appear within 12-72 hours.

The most common symptoms are:

  • Fever
  • Abdominal cramps
  • Diarrhea
  • Depression
  • Nausea
  • Vomiting
  • Won't eat

Diagnosis of Salmonellosis

Diagnosis is made by stool sample testing. Because many animals and humans recover on their own, many cases are not diagnosed/reported as Salmonellosis.

The CDC tracks human and pet food-borne illnesses through food supply surveillance programs. This is how information that led to the April 2012 dog food recall was discovered and collected.

Treatment for Salmonellosis

Many pets and humans recover from Salmonellosis with rest, oral fluids and bland diet in a week or less. However, prolonged and severe cases often require hospitalization for IV fluid support and antibiotics. Salmonellosis may be a severe and fatal disease for susceptible individuals (young, old, ill pets and people).

As always, if your pet is ill - vomiting, having diarrhea, depressed, or otherwise "not him or herself," please consult with your veterinarian sooner rather than later. This is especially true for puppies, kittens, senior pets, and animals with other conditions or diseases present.

Prevention of Salmonellosis

Food contaminated with Salmonella typically does not look, smell, or taste different than safe food. Proper hygiene and safe handling of cooked and raw foods is key for prevention of this disease.

Use lots of warm soapy water for hands, utensils and food preparation surfaces. Keep raw foods separate from prepared foods, use separate tools for raw and prepared foods, and cook meats, eggs and fish thoroughly.

Additional food safety tips for humans may be found on the USDA Salmonella Q&A site.

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