Salmonellosis in Dogs, Cats, and Birds

TL;DR. Salmonellosis is an uncommon but potentially serious bacterial infection in dogs, cats, and birds that can cause severe digestive upset or systemic illness, requiring careful veterinary diagnosis and supportive treatment.

Salmonella enterica bacteria target the lining of the gastrointestinal tract, causing inflammation.

What is it?

Salmonellosis is an uncommon bacterial infection caused by various serovars (strains) of the bacterium Salmonella enterica. While many people associate Salmonella primarily with foodborne illness in humans, this pathogen can also infect companion animals, including dogs, cats, and birds. In wild birds and the outdoor cats that hunt them, the disease is sometimes colloquially referred to as "Songbird fever."

In many pets, a Salmonella infection is subclinical, meaning the animal carries and sheds the bacteria in their feces without showing any outward signs of illness. However, when the bacteria actively cause disease, they primarily target the gastrointestinal tract. The bacteria use specialized mechanisms to attach to and invade the cells lining the intestines. Once inside, they trigger a profound inflammatory response, leading to gastroenteritis (inflammation of the stomach and intestines). In severe or untreated cases, particularly in vulnerable animals, the bacteria can breach the intestinal barrier entirely and enter the bloodstream. This systemic spread, known as bacteremia or septicemia, can lead to widespread inflammation, multi-organ dysfunction, and potentially fatal septic shock.

Because healthy pets can carry the bacteria without showing signs, veterinary scientists have long debated the exact role of Salmonella in mild digestive cases. As noted in a leading veterinary critical care textbook:

"Controversy continues regarding whether some of these organisms truly cause clinical disease because so..." — Small Animal Critical Care Medicine, p. 691

Despite this controversy, when clinical disease does occur, it can progress rapidly and requires immediate veterinary attention to prevent systemic complications.

Causes & risk factors

Salmonellosis is caused by the ingestion of Salmonella enterica bacteria. There are thousands of serovars of this bacterium, but some are more clinically relevant to pets than others. For example, Salmonella Typhimurium is one of the most common strains associated with illness in domestic animals. Interestingly, Salmonella Typhi, the strain responsible for typhoid fever in humans, does not affect dogs.

Pets typically acquire the infection through the fecal-oral route. This occurs when an animal ingests food, water, or environmental materials contaminated with infected feces. Common sources of infection include:

• Feeding raw meat diets or undercooked poultry.
• Contaminated commercial pet foods or treats (which are occasionally recalled due to Salmonella contamination).
• Scavenging dead wildlife or consuming contaminated surface water.
• Direct contact with the feces of infected animals, including wild birds or reptiles.

The bacteria are remarkably hardy and can persist in the environment for extended periods, making contaminated yards, cages, or bowls ongoing sources of exposure. A prominent veterinary internal medicine reference notes:

"S. enterica can survive for relatively long periods in the environment, and transmission through food, water, or fomites co..." — Small Animal Critical Care Medicine, p. 548

There are no known breed predispositions for Salmonellosis in dogs or cats. However, certain risk factors make some pets far more susceptible to developing severe, clinical disease:

• Age: Very young puppies and kittens, as well as geriatric pets, have less robust immune systems.
• Immune Status: Animals with underlying diseases (such as cancer, feline leukemia virus, or feline immunodeficiency virus) or those receiving immunosuppressive therapies.
• Hospitalization: Extended stays in veterinary hospitals can increase exposure risks, especially if hygiene protocols are compromised or if the pet is on concurrent therapies.

Signs to watch for

The clinical signs of Salmonellosis can range from mild, self-limiting diarrhea to severe, life-threatening systemic illness.

Common signs

• Fever: A sudden, high spike in body temperature is a frequent indicator of active bacterial infection.
• Anorexia: A complete loss of appetite or refusal to eat.
• Gastroenteritis: General digestive distress, including abdominal discomfort.
• Acute diarrhea: Sudden onset of loose, watery stools.
• Lethargy: Marked weakness, depression, or reluctance to move.
• Subclinical infection: Carrying and shedding the bacteria without showing any clinical signs.

Occasional signs

• Vomiting: Frequent vomiting, which compounds dehydration.
• Hemorrhagic diarrhea: Stool containing frank blood or having a dark, tarry appearance.
• Dehydration: Dry gums, loss of skin elasticity, and sunken eyes.
• Abdominal pain: Whining, guarding the belly, or adopting a "play bow" posture to relieve pressure.
• Bacteremia and septicemia: The spread of bacteria into the bloodstream, causing systemic illness.
• Septic shock: A critical drop in blood pressure, weak pulses, and pale gums.
• Neutropenia: A dangerous drop in neutrophils (a type of white blood cell) as the body struggles to fight the infection.
• Chronic diarrhea: Diarrhea that persists for weeks, leading to weight loss and poor body condition.
• Reproductive complications: Abortion or stillbirth in pregnant animals, or sudden neonatal death in newborn litters.

Rare signs

• Polyarthritis: Joint inflammation leading to shifting lameness and swollen, painful joints.
• Central nervous system signs: Seizures, tremors, or incoordination if the bacteria reach the brain or spinal cord.
• Pneumonia: Respiratory distress, coughing, and labored breathing.
• Sudden death: Occurs rapidly in severe septicemic cases, especially in newborns or immunocompromised individuals.

Lethargy and dehydration are common signs of systemic Salmonellosis in cats.

How vets diagnose it

Diagnosing Salmonellosis requires a combination of clinical history, physical examination, and specific laboratory testing. Because healthy pets can shed Salmonella in their feces, simply identifying the bacteria in a stool sample does not automatically prove it is the primary cause of your pet's illness. Your vet must correlate test results with your pet's clinical signs.

Key diagnostic tests include:

1. Fecal PCR (Polymerase Chain Reaction): This rapid test detects the genetic material (DNA) of Salmonella in the stool. It is highly sensitive and provides quick results, helping vets rule out or suspect the infection early.
2. Fecal Culture: This test involves placing a stool sample on special growth media to isolate and identify live Salmonella bacteria. It also allows the laboratory to perform antimicrobial sensitivity testing, which determines which antibiotics are most effective against that specific bacterial strain.
3. Blood Culture [GOLD STANDARD]: If your pet is showing systemic signs of illness (such as a high fever, severe lethargy, or low white blood cell counts), your vet will perform a blood culture. This is the gold standard for diagnosing bacteremia or septicemia. It involves drawing sterile blood samples and incubating them to see if Salmonella grows, confirming that the bacteria have entered the bloodstream.

Additionally, your vet will likely recommend a Complete Blood Count (CBC) to look for characteristic changes like neutropenia (low white blood cells) and a biochemistry profile to assess organ function and electrolyte imbalances caused by dehydration.

A blood culture is the gold standard test for diagnosing systemic Salmonella infections.

Treatment options

The treatment strategy for Salmonellosis depends heavily on the severity of the clinical signs.

Supportive Care

For pets with uncomplicated gastroenteritis (mild diarrhea and vomiting without systemic signs), the primary treatment is supportive care. This includes:

• Fluid Therapy: Intravenous (IV) or subcutaneous fluids to restore hydration and correct electrolyte imbalances.
• Nutritional Support: Offering a highly digestible, bland diet once vomiting is controlled to support intestinal healing.
• Gastrointestinal Protectants: Medications to soothe the stomach lining and manage nausea.

Antibiotic Therapy

The use of antibiotics in pets with Salmonellosis is highly selective and controversial. In stable pets with localized digestive signs, antibiotics are generally avoided. Using them indiscriminately can disrupt the normal gut microbiome, prolong the shedding of the bacteria in the feces (increasing the risk to other pets and humans), and promote antibiotic resistance. As noted in veterinary literature:

"Indiscriminate use of antimicrobials, inadequate hygiene, and extended hospital stays are among the proposed reasons for resistance to these commonly used agents..." — Small Animal Critical Care Medicine, p. 548

However, if your pet shows signs of systemic illness, such as a high fever, severe neutropenia, or confirmed septicemia, prompt antibiotic therapy is critical to prevent fatal septic shock. Your vet will select an appropriate antibiotic class, often starting with broad-spectrum coverage and adjusting based on blood or fecal culture sensitivity results.

Prognosis

The prognosis for pets with Salmonellosis is generally favorable and self-limiting for uncomplicated, localized gastrointestinal cases. With appropriate supportive care, the mortality rate during the acute stages of uncomplicated disease is less than 10%, and most pets make a full recovery.

However, the prognosis becomes guarded if the pet develops systemic complications such as bacteremia, septicemia, septic shock, or multi-organ dysfunction. These conditions are life-threatening and require intensive, round-the-clock veterinary care.

For exotic species or wild birds, clinical data is more limited, and much of our veterinary guidance is extrapolated from domestic canine and feline medicine. In songbirds, the disease is often highly fatal, while in domestic cats that contract "Songbird fever," the prognosis remains guarded to favorable depending on how quickly supportive treatment is initiated.

Prevention

Preventing Salmonellosis involves minimizing exposure to the bacteria and practicing excellent hygiene:

• Dietary Safety: Avoid feeding raw meat or raw food diets to your pets. Ensure all commercial foods are stored properly and keep track of any manufacturer recalls.
• Hygiene: Wash your hands thoroughly with soap and water after handling pet food, treats, or cleaning up pet waste. Clean and disinfect pet bowls, toys, and bedding regularly.
• Wildlife Management: Keep cats indoors to prevent them from hunting wild birds and rodents, which are common carriers of Salmonella. If you maintain outdoor bird feeders, clean and disinfect them weekly with a diluted bleach solution to prevent outbreaks of "Songbird fever" among wild populations.
• Zoonotic Precautions: Because Salmonella can easily spread from pets to humans, isolate any sick pet from young children, elderly family members, or anyone with a compromised immune system.

When to call your vet

If your pet shows mild digestive upset, monitor them closely. However, you should contact your vet immediately or seek emergency care if you observe any of the following red flags:

• Severe, bloody diarrhea (hemorrhagic diarrhea)
• High fever accompanied by extreme lethargy or collapse
• Persistent vomiting and inability to keep water down
• Signs of severe abdominal pain (whining, guarding the belly, or stretching constantly)
• Known ingestion of raw meat or contact with sick wild birds followed by sudden illness

Sources

• Textbook of Veterinary Internal Medicine, p. 496, 1425
• Small Animal Critical Care Medicine, p. 548, 691