CONDITION
Salmonellosis
Salmonellosis is an infection caused by Salmonella bacteria, which can affect the gastrointestinal tract and, in some cases, spread more widely through the body. These bacteria are found in many environments and can be carried by animals without causing illness, but they may also trigger disease, particularly in young animals, those with weakened immune systems, or pets under stress. In dogs and cats, infection often follows ingestion of contaminated food, water, or material from the environment. Owners most commonly notice sudden onset of diarrhoea, which may contain blood or mucus, often accompanied by vomiting, reduced appetite, and lethargy. Some animals show mild signs that resolve quickly, while others become unwell enough that dehydration or systemic effects develop. Occasionally, a pet may carry the bacteria without appearing ill, raising questions about household risk or transmission. This page explores the signs that may prompt concern, what happens in the body during infection, how the condition is investigated through laboratory testing and clinical assessment, and the range of supportive and antimicrobial approaches that may be considered depending on severity and individual factors.
Why this matters now
Salmonellosis can occur at any age, but younger animals—puppies and kittens under six months—tend to be more susceptible, as their immune systems are still developing and their gut barriers are less robust. Animals with concurrent illness, those receiving immunosuppressive medications, or pets experiencing significant stress from recent surgery, rehoming, or travel may also be at higher risk. Dietary factors play a role; feeding raw meat, particularly poultry, or access to contaminated water sources, wildlife faeces, or environments with poor sanitation increases the likelihood of exposure.
In many cases, signs begin within 12 to 72 hours after ingestion of the bacteria, though the incubation period can vary. Some animals develop mild, self-limiting diarrhoea that resolves over a few days without intervention, while others progress to more severe gastrointestinal upset with dehydration, fever, and systemic involvement over the course of several days. Occasionally, bacteria may persist in the gut or spread to other tissues, leading to prolonged shedding or complications such as septicaemia, particularly in young or immunocompromised individuals.
Signals & patterns
Early signals
Sudden watery diarrhoea
The stool may appear loose, liquid, or unformed, and often has a foul odour. This is typically one of the first changes noticed and reflects irritation and inflammation of the intestinal lining.
Reduced appetite or meal refusal
A pet may show less interest in food or skip meals entirely. This often accompanies nausea and the body's response to infection.
Vomiting
Episodes may be intermittent or frequent, and can include food, bile, or clear fluid. Vomiting tends to appear early in the course of infection and may precede or accompany diarrhoea.
Lethargy or reduced activity
The animal may seem quieter, sleep more than usual, or show less enthusiasm for play or walks. This reflects the systemic impact of infection and the energy cost of mounting an immune response.
Abdominal discomfort
Some animals adopt a hunched posture, appear restless, or vocalise when the abdomen is touched. This can indicate cramping or pain from intestinal inflammation.
Later signals
Blood or mucus in stool
Streaks of fresh blood or a jelly-like mucus coating may appear as inflammation deepens in the intestinal wall. This suggests more significant damage to the gut lining.
Fever
Body temperature may rise above the normal range, often accompanied by shivering or warm ears. Fever reflects the immune system's attempt to control bacterial spread.
Signs of dehydration
Owners may notice dry gums, sunken eyes, or reduced skin elasticity when gently lifted. Dehydration develops when fluid losses from diarrhoea and vomiting outpace intake.
Weakness or collapse
In severe cases, an animal may struggle to stand, appear unsteady, or lie flat with little response to stimuli. This can indicate shock, septicaemia, or profound electrolyte imbalance.
Click to read about the biological mechanisms
How this is usually investigated
Options & trade-offs
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