Leptospirosis is a bacterial infection that cattle pass to each other mainly through urine, in shared water, feed and pasture. In many herds it never looks like an illness at all. The clue is cows that won’t stay pregnant. It is also one of the few cattle diseases a farmer can catch, which makes prevention as much about people as about cows.1MSD Animal Health Republic of Ireland. Leptospirosis One antibiotic injection can clear it, and vaccination largely prevents it, though tests often miss it.
Two Kinds of Lepto and Why Your Herd Might Not Look Sick
Only one strain is specialized to live in cattle. It is called hardjo, and it can infect animals of any age, including young calves.2The Cattle Site. Leptospirosis Because it is adapted to cattle, it usually causes no illness or only mild signs.3Journal of Veterinary Medicine. Diagnosis and Control of Bovine Leptospirosis The trouble is that it often settles in the kidneys and creates a carrier: a cow that sheds bacteria in her urine for a long time without looking sick.4Alabama Cooperative Extension System. Leptospirosis in Cattle: Signs, Treatment, and Prevention Hardjo can also persist in the reproductive tract.5Alabama Cooperative Extension System. Leptospirosis in Cattle: Signs, Treatment, and Prevention A single carrier can look perfectly healthy while contaminating water troughs and pasture, so buying a healthy-looking cow is no guarantee she is free of lepto.
Other strains, such as pomona, icterohaemorrhagiae, canicola and grippotyphosa, come from other animals, and cattle are only occasional hosts.6The Cattle Site. Leptospirosis These strains cause more severe and quite different illness.7The Cattle Site. Leptospirosis Rodents, deer, pigs and dogs can carry them, so an outbreak of the severe kind usually points to contact with wildlife or their urine. Hardjo and the wildlife strains can exist in the same herd, so a calf with red urine doesn’t rule out hardjo also circulating among the cows.
Signs of Leptospirosis in Cattle
In many herds, failing pregnancies are the only sign anyone sees.8Texas A&M Veterinary Medical Diagnostic Laboratory. Bovine abortion caused by leptospira spp. Watch for cows that return to heat, conceive poorly or lose early pregnancies.9PubMed Central. Bovine Genital Leptospirosis: An Update of This Important Reproductive Disease Early embryo loss is more common than late abortion.10PubMed Central. Bovine Genital Leptospirosis: An Update of This Important Reproductive Disease Abortions can happen any time from about 4 months of pregnancy to term.11dvm360. Leptospirosis in cattle Because the infection is long-lasting, poor fertility can continue for years.12PubMed Central. Bovine Genital Leptospirosis: An Update of This Important Reproductive Disease
A single cow that returns to heat or aborts has many possible causes, so lepto becomes more likely when several animals are affected over a season. Abortions are often spread over weeks or months rather than arriving in one wave, which can make each one look like bad luck. Written breeding records help: noting return-to-heat dates shows a rising rate of early loss, and a pregnancy check that finds many open cows is a warning sign.
Milking cows can show a sudden drop in yield 2 to 7 days after a susceptible cow is infected.13NADIS. NADIS – Leptospirosis The udder goes soft and flabby, with thick, colostrum-like or blood-tinged milk in all four quarters.14NADIS. NADIS – Leptospirosis Some cows are dull and stiff, with fever and a poor appetite, while others show signs too mild to notice.15NADIS. NADIS – Leptospirosis Ordinary mastitis usually affects one quarter and leaves the udder hot and hard. Several cows dropping milk within days of each other suggests a herd infection worth checking with your vet.
Calves tend to get a more severe illness than adults.16www.feedlotmagazine.com. Leptospirosis in Cattle Look for fever, depression, anaemia, small blood spots on the gums and red or dark urine, often called redwater.17The Cattle Site. Leptospirosis in dairy cattle Yellow gums and eyes from jaundice are a sign of severe infection.18www.feedlotmagazine.com. Leptospirosis in Cattle In one outbreak, young calves often died quickly, while older steers were dull, off feed, yellow and passing red urine.19PubMed Central. Acute Leptospirosis Outbreak in Cattle: A Case Report Lameness, being unable to stand and death occur in the most intense infections.20www.feedlotmagazine.com. Leptospirosis in Cattle
Red urine has other causes, including tick-borne disease and eating certain plants. Still, jaundice and red urine together in a calf need an urgent vet visit, and it helps to keep a urine sample from the animal for the vet.
How Cattle Catch Leptospirosis
Infected animals shed the bacteria mainly in urine, which spreads the disease directly or by contaminating drinking water, feed and pasture.21Texas A&M Veterinary Medical Extension. Leptospirosis in Cattle Bacteria can also be shed in milk and birth fluids, and occasionally spread at breeding.22Texas A&M Veterinary Medical Extension. Leptospirosis in Cattle They enter through the eyes, mouth, nose or damaged skin.23Texas A&M Veterinary Medical Extension. Leptospirosis in Cattle Small cuts and skin softened by water let them in too.24PubMed Central. The association between natural drinking water sources and the emergence of zoonotic leptospirosis among grazing beef cattle herds during a human outbreak
Wet ground, muddy gateways and shared ponds or streams favour spread, and cattle cases rise with more surface runoff and wetter soil.25PubMed Central. The effects of rain and flooding on leptospirosis incidence in sheep and cattle in New Zealand Rodents carry the bacteria in most parts of the world.26PubMed Central. Identification of cattle, buffaloes and rodents as reservoir animals of Leptospira in the District of Gampaha, Sri Lanka Deer infected with pomona are linked to pomona in nearby cattle.27PubMed. Comparison of antibodies to Leptospira in white-tailed deer (Odocoileus virginianus) and cattle in Ohio On a farm, the riskiest spots are natural ponds and streams that several herds or wildlife use, areas flooded after heavy rain, and feed stores where rats and mice can soil the feed.
A bull can spread lepto too. An infected bull can pass it to cows at breeding, and a borrowed or shared bull can bring it into a clean herd. If you treat and vaccinate the herd, the bull belongs in the plan.
Why Leptospirosis Is Hard to Diagnose
The usual blood test measures antibody level, which a lab report gives as a titer, such as 1:100.28Journal of Veterinary Medicine. Diagnosis and Control of Bovine Leptospirosis With hardjo, cattle are often actively infected and shedding with a titer below 100.29Journal of Veterinary Medicine. Diagnosis and Control of Bovine Leptospirosis Up to half of cows aborting from hardjo test negative at the time of abortion.30Journal of Veterinary Medicine. Diagnosis and Control of Bovine Leptospirosis A low result therefore doesn’t rule out leptospirosis.31Journal of Veterinary Medicine. Diagnosis and Control of Bovine Leptospirosis
Using two tests catches more. In one dairy outbreak, the blood test and a DNA test of samples each found 10 of 17 infected cows, but together they found 14.32PubMed Central. Describing diagnosis (MAT + PCR) and control (vaccine + streptomycin sulfate) of a leptospirosis outbreak in dairy cows with reproductive disorders Each test picks up a different stage of infection.33PubMed Central. Describing diagnosis (MAT + PCR) and control (vaccine + streptomycin sulfate) of a leptospirosis outbreak in dairy cows with reproductive disorders Ask your vet about testing several animals with both methods. Vets read herd results alongside vaccination history, because vaccination also raises titers.
After an abortion, keep the aborted calf and afterbirth cool and call the vet. The lab can look for the bacteria directly in these tissues. Wear gloves, since these materials can infect people.
Treating Leptospirosis in Cattle
A single injection of streptomycin usually clears the carrier state in the kidneys.34Merck Veterinary Manual. Leptospirosis in Ruminants – Infectious Diseases – Merck Veterinary Manual A single injection of oxytetracycline or tilmicosin, or a dihydrostreptomycin-penicillin combination, has also been shown to stop urine shedding of hardjo.35PubMed. Evaluation of antibiotics for treatment of cattle infected with Leptospira borgpetersenii serovar hardjo Ceftiofur also works but needs daily injections for 3 to 5 days.36PubMed. Evaluation of antibiotics for treatment of cattle infected with Leptospira borgpetersenii serovar hardjo Treatment can prevent abortions and other reproductive problems.37Merck Veterinary Manual. Leptospirosis in Ruminants – Infectious Diseases – Merck Veterinary Manual Dose, drug choice and milk and meat withdrawal times must come from your vet.
Withdrawal periods differ between drugs, and treated cows must stay out of the supply for the stated time. Treating without a diagnosis can waste money, because other causes of abortion don’t respond to these antibiotics.
In a herd where lepto is confirmed, cows that look fine need treating too. Carriers keep reinfecting the herd if only sick cows are treated, and treating everyone at once breaks the cycle. Vaccination afterwards keeps cleared cows from catching it again.
In herds known to be infected, a long-acting oxytetracycline injection under the skin can be given at the first vaccination.38University of Tennessee Extension. Leptospirosis in Beef Cattle Include the bull in the program.39University of Tennessee Extension. Leptospirosis in Beef Cattle Isolate new cattle for 1 month, vaccinate them and give oxytetracycline before they join the herd.40University of Tennessee Extension. Leptospirosis in Beef Cattle
Sick calves need more than antibiotics. Those with anaemia and jaundice may need fluids and nursing care, and the vet may decide a calf is too ill to save.
Preventing Leptospirosis with Vaccination and Herd Management
Hardjo vaccines prevent about 9 in 10 cattle from shedding the bacteria in urine.41PubMed. Meta-analysis of the efficacy of Leptospira serovar Hardjo vaccines to prevent urinary shedding in cattle That cuts spread within the herd and to the people who work with it.42PubMed. Meta-analysis of the efficacy of Leptospira serovar Hardjo vaccines to prevent urinary shedding in cattle Your vet can advise a vaccine that covers the strains in your area.
Vaccination is not a perfect shield, so rodent control, clean water and quarantine still matter. A vaccine matched to hardjo may not cover strains carried by wildlife, so ask which are present locally.
A usual routine is two initial doses a few weeks apart for young stock, then a booster every year before breeding. Vaccinate bulls and replacement heifers too.
Management closes the other doors. Rodents are the most important carriers of lepto among mammals, and in one region, large-scale rat control cut human cases by 82%.43Journal of Communicable Diseases. Rodent Control a Tool for Prevention of Leptospirosis – A Success Story on Human Leptospirosis with Gujarat State Keep feed stores rodent-proof and control rats and mice around farm buildings. Fence off natural ponds and streams and provide clean trough water.
When buying or borrowing cattle, ask the seller about lepto vaccination history and avoid sharing bulls with herds of unknown status. After a flood or wet season, move cattle off flooded pasture when possible, check water sources that wildlife use, and watch breeding results closely in the months after.
Protecting Yourself From Leptospirosis
Farmers, farm workers, slaughterhouse workers and vets are the main people at risk.44MSD Animal Health Republic of Ireland. Leptospirosis They catch it from the urine, afterbirth or aborted calves of infected cattle, or from contaminated water.45MSD Animal Health Republic of Ireland. Leptospirosis Among dairy workers in one area, about 1 in 10 showed signs of past infection.46International Journal of Veterinary Sciences and Animal Husbandry. Seroprevalence of leptospirosis in dairy cattle and occupational risk assessment among dairy farm workers Direct contact with cattle urine, milking without gloves and open cuts on the hands raised the risk.47International Journal of Veterinary Sciences and Animal Husbandry. Seroprevalence of leptospirosis in dairy cattle and occupational risk assessment among dairy farm workers
In people it often starts like flu, with fever, headache and muscle aches. Severe cases can affect the kidneys and liver. If you get a fever, tell your doctor you work with cattle.
Milking is risky because urine splashes toward the face, and eye protection helps in the parlour. Calving and handling aborted calves expose your hands to birth fluids. Wear gloves for milking, births and aborted calves, cover cuts on your hands and wash after work.
What Leptospirosis Costs a Herd
Long-term infertility is perhaps lepto’s most costly effect.48Alabama Cooperative Extension System. Leptospirosis in Cattle: Signs, Treatment, and Prevention On one dairy farm, the outbreak cut profit per litre by up to 84%.49PubMed. Estimation of economic losses due to leptospirosis in dairy cattle After treatment and control, yearly milk sales there rose from about 165,000 to 249,000 litres in three years.50PubMed. Estimation of economic losses due to leptospirosis in dairy cattle Empty cows eat feed without producing a calf, longer calving intervals spread out the calving season, and culling and replacing cows adds expense.
For beef herds, fewer calves at weaning is the main loss, and late-born calves weigh less at sale. Good pregnancy checks show the loss early.