Salmonella is a bacteria that can have devastating effects on your horse’s intestinal tract. At the least, it can be a management nightmare with heavy diarrhea, fever and dehydration. At the worst, it can result in laminitis or death and hit all the horses in your barn.
Every horse is at risk of salmonella. Your own apparently healthy animal may harbor the organism in small numbers in his own gut, as could any cat, dog, bird, squirrels or other small rodent, animal or reptile.
At least one in every six horses sheds salmonella organisms in his manure on a regular basis and a much higher number probably carry the organism as well, although usually in small numbers that make it difficult to culture.
When a salmonella infection sweeps through a farm, racetrack or animal hospital, you may be dealing with a particularly pathogenic strain of salmonella or simply with large numbers of salmonella organisms contaminating the environment.
The horse’s primary defense against salmonella is a thriving population of beneficial organisms in his gut, a normally functioning strong immune system, a normal production of stomach acid and a smoothly functioning digestive tract, the latter also being an essential condition for maintaining good numbers of beneficial bacteria.
Risk factors for salmonella include:
• Exposure to manure from an animal with an active salmonella infection or one that is immune but shedding large numbers of organisms.
• Use of antibiotics, especially oral antibiotics, but intravenous antibiotics may interfere with normal intestinal populations also.
• Colic of any cause, colic surgery, or anything that causes the horse to go off feed.
• Drugs that influence intestinal motility, decrease/neutralize stomach acid secretion or cause breaks in the intestinal lining.
• Significant stress or illness of any type or drugs that lower immunity, such as corticosteroids.
You can reduce your horse’s risk by:
• Meticulous and regular removal of manure.
• Cleaning and periodic disinfection of water buckets and feed troughs.
• Disinfection of stalls between horses.
• Not feeding your horse off the ground, especially away from home.
• Feed plenty of hay and other highly digestible fiber feeds like beet pulp to maintain good numbers of beneficial bacteria.
• Avoid unnecessary or prolonged use of antibiotics.
• Enforce immediately strict isolation of any horse with diarrhea until the cause can be determined.
• Minimize rodent, bird and small-animal traffic in the horse’s stall.
Treatment And Prognosis
Although salmonella is a bacterial infection, antibiotics aren’t particularly successful in eliminating it, at least from the intestinal tract. Plus, they carry a risk of being more active against the beneficial bacteria than the salmonella, which could make things worse.??
Antibiotics usually are only used when the horse shows clear evidence that the bacteria have actually invaded the blood stream.?? Otherwise, good supportive care with fluids, correction of electrolytes, pain medications, anti-inflammatories and plasma, if needed, are the mainstays of treatment.
Whether or not the horse recovers depends on a number of factors, including any other diseases/stressors he may have, age (very young and very old horses), and how severe the signs are.?? With good supportive care, salmonella may run its course in five to seven days, although the horse may continue to have episodes of soft manure for a few months and could shed significant levels of the bacteria for that long as well, especially if he is stressed.