Leptospirosis is a bacterial disease that is considered uncommon in goats but is zoonotic and contagious, not to be confused with listeriosis. While the bacteria thrives in warm, wet weather, it is possible just about anywhere – I found confirmed cases of lepto in dairy cattle in Minnesota, for instance – and it can live as long as six months in damp soil.
How do goats get leptospirosis? Unfortunately, many wild and domestic animals and birds can carry the bacteria. Rodents are a common source of infection, and urine is a common means of disease spread since the bacteria lives in the kidneys of its host. The bacteria enters the host through mucous membranes, cuts, or even abraded or softened skin. Contaminated soil, water, and mud can spread the bacteria. Smith and Sherman lists the incubation period as 4-8 days.
Below: Many sources pointed to periods of flooding in warm months as catalysts for outbreaks. Just a note that this is my own barn, flooded in the middle of the night because a pond far up the holler had overflowed. I thankfully did not have any issues with leptospirosis (and have never, to my knowledge).
Leptospirosis is often subclinical. The most common symptom in goats infected with leptospirosis is fertility issues like abortions, stillborns, embryonic reabsorptions, and neonatal deaths. Source five notes rough, dry coats in adult animals. Blood-tinged milk is a common symptom occurring in infected goats, as well as reduced milk production. In this interesting case study, a doe presented with mastitis-like symptoms that were actually a manifestation of leptospirosis - https://www.thepharmajournal.com/archives/2020/vol9issue8S/PartB/S-9-7-25-306.pdf
Death from an acute infection in any animal can occur in as little as 2 to 3 days. “In animals that survive acute infection, a strong immunity develops against the inciting serovar, but cross immunity does not occur” (Smith and Sherman 291). The host animal can suffer from anemia, fever, jaundice, anorexia, diarrhea, and, according to the National Library of Medicine, "small pin-point hemorrhages in the eye lining.” In addition to suffering from anemia, goats with an acute leptospirosis infection might pass reddish brown urine indicative of renal failure since the red blood cells are rupturing. In New Zealand and subtropical countries where leptospirosis is more widespread, it is noted that high fever often precedes death in young kids, especially.
Diagnosis is tricky, especially since symptoms are similar to many other more common issues, and also because there are so many lepto serovars. Urine and/or blood samples from live animals and aborted tissue are often used – this source goes into detail about some of the difficulties diagnosing the disease: https://www.nature.com/articles/s41598-022-05767-x and this page from Cornell’s website touches on some of the difficulties as well as shares a table of result interpretations - https://www.vet.cornell.edu/animal-health-diagnostic-center/testing/protocols/leptospira-microagglutination
Treatment is thankfully more straight forward than diagnosis. According to Goat Medicine, antibiotics of choice include penicillin and oxytetracycline (Smith and Sherman 292). While many factors, such as warm temperature and/or rainfall, are out of the producers’ control, managing some environmental aspects can aid in the prevention of leptospirosis outbreaks. Clean, dry bedding and feeding areas make it difficult for lepto to live outside of host animals. Minimizing or eliminating rodents is also beneficial, not just in living areas but haystacks and barns as well. Currently, leptospirosis vaccines used in goats are those labeled for cattle and “...suffer from questionable efficacy and duration of immunity even in labeled species” - Sheep, Goat, and Cervid Medicine (Pugh 288). Since the disease isn’t prevalent in the United States, not many producers choose not to vaccinate their goats for leptospirosis.
Even though it is not common, leptospirosis is possible and learning more about it might offer some insight in the event a herd is dealing with either acute or chronic issues without differential diagnosis.
https://www.merckvetmanual.com/generalized-conditions/leptospirosis/leptospirosis-in-ruminants
https://www.dairynz.co.nz/animal/animal-health/leptospirosis/
Pugh D G. Sheep. Goat, and Cervid Medicine. Elsevier, 2021.
Smith, Mary C., and David M. Sherman. Goat Medicine. 2nd ed., Wiley-Blackwell, 2009.