Cow Tales: Leptospirosis – the downward spiral | TSLN.com

Cow Tales: Leptospirosis – the downward spiral

Kenny Barrett Jr., DVM, MS

It is only human nature to accept a routine. However, occasionally we need to examine our standard practices and reassess their worth and purpose.

Cattlemen have traditionally vaccinated adult cows against vibrio and lepto at pregnancy diagnosis. Both are bacteria that cause reproductive losses. Vibrio, now renamed Campylobacter, is well controlled with vaccination. Many practicing veterinarians are hard pressed to remember a vibrio abortion in cattle.

Lepto, on the other hand, has been much more difficult to control. The nuances of naming, environment, clinical signs, vaccination, etc., have made lepto more challenging to master. As a result, it is difficult to discuss leptospirosis without getting bogged down in technical information.

Leptospira are bacteria with an unusual shape resembling a spiral staircase. Leptospirosis is wide-spread in the animal kingdom and causes disease in many species. Additionally, there are many species of leptospira bacteria. Each species is further classified into numerous serovars. Each serovar is perpetuated through chronic or long-lasting infections in specific maintenance hosts. So cattle, dogs, raccoons, etc., act as maintenance hosts for different serovars of leptospira.

Cattle in the U.S. are the maintenance host for Leptospira borgpetersenii serovar hardjo-bovis or lepto hardjo-bovis that has gained popularity in the recent press. You can think of each subdivision of bacteria as genetically prejudice parasites. Most animals can become transiently infected by “non-maintenance” serovars which cause severe acute disease. Cattle with this type of infection are clinically ill.

Like lepto, I too have a “maintenance host” – beef. I prefer steak almost all the time. That is my “maintenance” food. But occasionally I will step out and order pork, chicken, or seafood. The good news is they don’t make me clinically ill. Lepto serovars prefer their specified host, but can infect lots of different animals, including people.

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Producers may have a lepto problem and not even know it. Chronic infections rarely produce obvious disease. Instead producers can expect decreased fertility, early embryonic death, abortions, or weak calves that fail to thrive. Cows affected early in the breeding season may rebreed and show up as “lates” during the fall preg check. Producers need to recognize the intangible losses as potential disease problems. Very rarely do we encounter abortion storms where six-month-old fetuses are found in numbers that cause concern.

When lepto is suspected it can be hard to diagnose for numerous reasons. A combination of blood and urine are required to establish lepto as a problem with any certainty. Lepto infections usually occur weeks to months before we ever notice a problem. Antibodies produced during infection are short lived and levels are generally low or nonexistent when we observe an aborted fetus. Urine samples can be examined for the presence of leptospira organisms or their DNA. However, urinary shedding can be intermittent and lead to false negatives. In short, lepto most commonly causes insidious disease and is difficult to accurately diagnose.

Traditional lepto vaccines are 5-ways with five different serovars from two species of leptospira. Only two vaccine lines include lepto hardjo-bovis, the serovar using cattle as their preferential host. The usual dogma would suggest vaccination is serovar-specific with vaccination providing protection only against the serovars included in the vaccine. However, one company has provided evidence of some cross protection against lepto hardjo-bovis.

Additionally, lepto vaccines are thought to produce a relatively short-lived immune response. The body seems to forget about the vaccine. Some vaccine labels are now claiming one year of protection against lepto hardjo-bovis. Still, we need to remember the other serovars of lepto when we vaccinate. In general, the immune response to lepto vaccination is good, but seems to be short lived. In our clinic we recommend administration of lepto vaccines in the fall. This is the time of year we feel has the greatest risk of transmission. We want peak protection to coincide with peak challenge.

Leptospira are transmitted in urine and survive well in water and moist soils. The reproductive tract of both bulls and cows can serve as a source of infection. Cattle typically spend the summer grazing large areas in western rangelands. The stocking density is the lowest during the warm months of the year. Towards winter the animals are concentrated in working facilities, corrals, and more importantly, on winter feeding grounds. We feel this poses the greatest risk of coming into contact with contaminated urine. Therefore, we believe vaccination is best when administered close to the greatest challenge. The organisms can invade the host animal through abraded skin or mucous membranes. They can be spread through ingestion, copulation, or be passed to the developing fetus in utero.

Leptospirosis is a complicated disease leading to abortion breaks and more commonly insidious reproductive losses. The bacteria, the disease, prevention and control are rather challenging to master. Producers need to work with their veterinarians when trying to manage the disease. Vaccination and testing are important, but also have their shortcomings. You may need to visit with your veterinarian if you are dissatisfied with the reproductive rates in the cowherd or have difficulty getting heifers pregnant. You might be on a slippery downhill spiral with leptospirosis.

It is only human nature to accept a routine. However, occasionally we need to examine our standard practices and reassess their worth and purpose.

Cattlemen have traditionally vaccinated adult cows against vibrio and lepto at pregnancy diagnosis. Both are bacteria that cause reproductive losses. Vibrio, now renamed Campylobacter, is well controlled with vaccination. Many practicing veterinarians are hard pressed to remember a vibrio abortion in cattle.

Lepto, on the other hand, has been much more difficult to control. The nuances of naming, environment, clinical signs, vaccination, etc., have made lepto more challenging to master. As a result, it is difficult to discuss leptospirosis without getting bogged down in technical information.

Leptospira are bacteria with an unusual shape resembling a spiral staircase. Leptospirosis is wide-spread in the animal kingdom and causes disease in many species. Additionally, there are many species of leptospira bacteria. Each species is further classified into numerous serovars. Each serovar is perpetuated through chronic or long-lasting infections in specific maintenance hosts. So cattle, dogs, raccoons, etc., act as maintenance hosts for different serovars of leptospira.

Cattle in the U.S. are the maintenance host for Leptospira borgpetersenii serovar hardjo-bovis or lepto hardjo-bovis that has gained popularity in the recent press. You can think of each subdivision of bacteria as genetically prejudice parasites. Most animals can become transiently infected by “non-maintenance” serovars which cause severe acute disease. Cattle with this type of infection are clinically ill.

Like lepto, I too have a “maintenance host” – beef. I prefer steak almost all the time. That is my “maintenance” food. But occasionally I will step out and order pork, chicken, or seafood. The good news is they don’t make me clinically ill. Lepto serovars prefer their specified host, but can infect lots of different animals, including people.

Producers may have a lepto problem and not even know it. Chronic infections rarely produce obvious disease. Instead producers can expect decreased fertility, early embryonic death, abortions, or weak calves that fail to thrive. Cows affected early in the breeding season may rebreed and show up as “lates” during the fall preg check. Producers need to recognize the intangible losses as potential disease problems. Very rarely do we encounter abortion storms where six-month-old fetuses are found in numbers that cause concern.

When lepto is suspected it can be hard to diagnose for numerous reasons. A combination of blood and urine are required to establish lepto as a problem with any certainty. Lepto infections usually occur weeks to months before we ever notice a problem. Antibodies produced during infection are short lived and levels are generally low or nonexistent when we observe an aborted fetus. Urine samples can be examined for the presence of leptospira organisms or their DNA. However, urinary shedding can be intermittent and lead to false negatives. In short, lepto most commonly causes insidious disease and is difficult to accurately diagnose.

Traditional lepto vaccines are 5-ways with five different serovars from two species of leptospira. Only two vaccine lines include lepto hardjo-bovis, the serovar using cattle as their preferential host. The usual dogma would suggest vaccination is serovar-specific with vaccination providing protection only against the serovars included in the vaccine. However, one company has provided evidence of some cross protection against lepto hardjo-bovis.

Additionally, lepto vaccines are thought to produce a relatively short-lived immune response. The body seems to forget about the vaccine. Some vaccine labels are now claiming one year of protection against lepto hardjo-bovis. Still, we need to remember the other serovars of lepto when we vaccinate. In general, the immune response to lepto vaccination is good, but seems to be short lived. In our clinic we recommend administration of lepto vaccines in the fall. This is the time of year we feel has the greatest risk of transmission. We want peak protection to coincide with peak challenge.

Leptospira are transmitted in urine and survive well in water and moist soils. The reproductive tract of both bulls and cows can serve as a source of infection. Cattle typically spend the summer grazing large areas in western rangelands. The stocking density is the lowest during the warm months of the year. Towards winter the animals are concentrated in working facilities, corrals, and more importantly, on winter feeding grounds. We feel this poses the greatest risk of coming into contact with contaminated urine. Therefore, we believe vaccination is best when administered close to the greatest challenge. The organisms can invade the host animal through abraded skin or mucous membranes. They can be spread through ingestion, copulation, or be passed to the developing fetus in utero.

Leptospirosis is a complicated disease leading to abortion breaks and more commonly insidious reproductive losses. The bacteria, the disease, prevention and control are rather challenging to master. Producers need to work with their veterinarians when trying to manage the disease. Vaccination and testing are important, but also have their shortcomings. You may need to visit with your veterinarian if you are dissatisfied with the reproductive rates in the cowherd or have difficulty getting heifers pregnant. You might be on a slippery downhill spiral with leptospirosis.

kenny barrett jr. is a veterinarian at the belle fourche veterinary clinic in belle fourche, sd and pens “cow tales” monthly. learn more about the clinic on the web at http://www.bfvetclinic.com, or drop them an e-mail at: office@bfvetclinic.com to suggest a topic for the next installment of “cow tales.”

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