Salmonella in Cattle

By: Dr. Dan Thomson, Production Animal Consultation

Salmonella is one of the oldest and most recognized bacteria that cause disease in many species of animals including humans. Salmonella is a gram-negative bacterium that causes diarrheal diseases in neonates of many species, wide-spread septicemia in dairy cattle and respiratory disease in swine.

Salmonella bacteria cause diarrhea and other diseases in beef cattle. There are two reasons why animals get sick: 1) an overwhelming dose of a pathogen (like Salmonella) or 2) a suppressed immune system of the animal.

The cattle most susceptible to Salmonella infections are young calves and older cows. Salmonella species are abundant in the environment and cattle become exposed to Salmonella by ingesting fecal particulate while nursing or when drinking from a water tank or eating from contaminated feed when an animal defecates in the tank or bunk. While cattle can carry Salmonella without showing any signs of illness, wildlife such as birds, rodents and feral cats can carry Salmonella and spread the pathogen in places they congregate on the farm. Salmonella can survive in fecal matter for extended periods of time in the environment and generally are higher in concentration in areas where cattle congregate like feed bunks, water tanks, bale rings and barns.

Cattle that become ill from a Salmonella infection can exhibit many different clinical signs. Salmonella infections in baby calves generally occur between 2 and 12 weeks of age. Calves will have diarrhea, depressed appearance, dehydration, general weakness and a fever (figure 1).

Feedlot calves that contract Salmonella infections are in poor body condition and have a watery diarrhea, depression, dehydration and an elevated rectal temperature. Many times, Salmonella-infected feedlot cattle will also have other types of infections such as respiratory disease, liver disease or general septicemia.

Older cows that contract Salmonella will be thin, have elevated rectal temperature and be in very poor health. Cows may or may not have diarrhea but many Salmonella infections produce septicemia in older cows.

Diagnosis of Salmonella infections is easier in the neonatal calf than in older cattle. If an animal dies, a veterinarian can conduct a necropsy examination and take samples such as feces, gut loops, lung, heart, kidney and others for isolation of viruses or bacteria such as Salmonella.

One can also take fecal, feed, water or environmental samples during the time of a potential Salmonella outbreak. It takes 4 to 5 days to get results back from the diagnostic laboratory on bacterial isolation from these samples. Many times when neonatal calves break with Salmonella or another scours pathogen, it is recommended to take the dead calf intact to the diagnostic laboratory to improve the chances of getting the right samples and enhance sample integrity.

Figure 1: Calf scours environment. As mentioned above, wildlife can carry Salmonella and you should control birds, varmints, cats and other animals on your cattle facilities as much as possible. Salmonella can survive for days, even weeks, in the environment. Manure management and mud management is vitally important.

Salmonella is a vicious zoonotic disease that people can acquire from cattle and calves. People become infected by consuming fecal particles or diarrhea when they work with infected cattle. Do not bring calves into your kitchen or bathroom to warm them up. There have been cases of young children becoming ill and even dying from Salmonella after drinking bath water following a calf being warmed up in the bathtub the day before.

Prevention of Salmonella is the best strategy as Salmonella infections are hard to treat in cattle. Many times Salmonella infections are self-limiting meaning that the calf or cow develops immunity against the pathogen and clears the bug itself.

It is important to provide supportive care to calves such as providing them fluids and keeping them warm and dry. Some people try to improve gut health by treating cattle with a probiotic. Antibiotics in Salmonella infections are administered orally to kill pathogens in the gut or through the syringe to treat septicemia. We recommend that producers work with their veterinarian to develop a judicious and proper antibiotic treatment program for Salmonella or other bacterial infections in cattle.

Prevention of Salmonella in cattle involves controlling pathogen exposure through decreasing environmental contamination and keeping the cattle’s immune systems functioning. Healthy cattle have functioning immune systems from proper housing, vaccination programs, nutrition, water and other good animal husbandry practices. It is important to keep balling guns, drench equipment and other instruments sanitary.

It would be best if new cattle are processed in a chute and facility different than the facility where sick animals are treated. However, if that is not possible, processing new cattle should be done prior to the treating of sick cattle for the day.

It is important to keep feed bunks and water tanks clean and move the bale rings around to give animals a cleaner

It is not recommended that colostrum or milk be warmed up in your kitchen for the same reasons. Keeping soiled boots and clothes away from crawling babies or toddlers in the house is a good prevention measure to think about. Lastly, wash your hands. When you get done working cattle or doing a necropsy, wash your hands with soap and dry them with a towel before eating or placing your tobacco between your cheek and gum.