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Welcome to the Lepto dog vaccine home page. Lepto is the short name of Leptospira, or Leptospirosis, a diseases that dogs can get from other dogs and wildlife. Lepto can be passed on to humans as Weil's disease - which can cause blindness and other issues in humans.

Leptospirosis is a group of zoonoses (transferable to humans) with many synonyms that refer to the area where the disease was contracted or the host or the symptoms of the profession or activity of the patient.

Leptospirosis was first described by Adolf Weil in 1886, but the causal relationship with leptospira is adopted only in 1908, when an outbreak of Weil's disease among miners in Japan. Since then Leptospira isolated from almost any mammalian species as well as some amphibians and reptiles on all continents of the world (except Antarctica).

Leptospira bacteria are corkscrew-like, and many types (called serovars) are known.

Lepto infection and symptoms

Cause of infection: Dogs become infected with Leptospires (an organism that thrives in water) by consuming urine contaminated water or contact with infected urine - such as sniffing, walking through or rolling in wet grass contaminated with lepto from another animal's urine. Leptospires use a dog’s kidneys to breed and continue living out their life cycle. Lepto strains that will infect dogs are known to be in Horses and Pigs, as well as rats, etc.

Symptoms include: fever, vomiting, depression, loss of appetite, generalised pain and conjunctivitis. Later symptoms include: a drop in temperature, increased thirst, change in urine colour, jaundice, frequent urination, dehydration, difficulty breathing, muscular tremors, vomiting and bloody faeces. Antibiotics can help shorten the length of the disease and reduce potential organ damage if caught in early stages. In more severe cases, kidney filtration and blood transfusion may be necessary. About 10% of Leptospirosis cases result in death from secondary complications.

Vaccination: The dog's immune system creates antibodies to help the dog fight the illness. Unlike the DHP vaccines, the Lepto vaccines do not prevent the dog from getting the disease, but helps the dog to combat the bacteria that it is vaccinated against.

If the vaccine for tetanus bacteria can last 10 or more years then why can't Lepto vaccine last that long?

A note by the website owner

With Lepto, it is a bit of Russian Roulette.


I'm not a vet. I cannot provide you any reassurance on vaccines. All that you can take from the data available is that out of some 6 million vaccines sold from the pharmaceuticals to the vets per year, some 5 thousand dogs have adverse reactions. This means that some 5 million 9 hundred and 95 thousand did not have an adverse reaction recorded - that doesn't mean something didn't happen. You also have to remember that some vaccines will have gone out of date or been broken, etc, so the figure of vaccines actually injected might be less than the 6 million sold to the vets. And there might be many dogs who had an adverse reaction who were not included in the figures due to the vet not accepting the symptoms being presented as being Lepto vaccine related - and therefore not reporting the case to VMD.


We will never know how many dogs have been helped by the vaccine to fight Lepto, and we've been completely oblivious to the incident. I personally regularly wonder as to how many dogs who suffer with kidney issues, had actually been infected by Lepto at some point but the vet has only diagnosed the kidney issue and missed the complete picture.


My personal experience with Lepto vaccines


I lost a cavalier to Zoetis' Lepto 4 after 9 years of his having Lepto 2 without issue. My vets and the independent post-mortem pathologist at Animal Health Trust were adamant that the sudden destruction of his heart strings within days of the vaccine were not related to the vaccine. I disagree.

My second cavalier was vaccinated at the same time. She had no adverse reaction, but had a lump at the point of vaccination (her last vaccine) for 4 years until her heart gave out - that gradual heart thing is a standard Cavalier thing, so expected.

My current cavalier (9 years old) had Duramune L2 as a pup and at age 1, and then Nobivac L4 at age 2 (her last vaccine) - and is curled up by my side with no effect. I'm not advocating Nobivac, I'm simply saying that we don't know who it will affect.


Lepto is not just carried by rats, but also by horses, pigs, cows, and many other mammals. It is not just transferred at rivers, but is more likely to be caught in stagnant ponds, grass where there infected animals reside, etc.

And we know from DEFRA's APHA that a very very small number of dogs in the UK have been infected by various strains of Lepto not covered by vaccines.


Do take a look at the FZ2100 Non statutory Zoonoses report - at Section 2.2.2

See https://www.gov.uk/government/publications/non-statutory-zoonoses-disease-surveillance-reports


Reporting adverse reaction to medicines.

Whilst the vet is expected to report an adverse reaction to VMD, there are cases where the vet refuses to accept that the vaccine caused the issue that is now presenting. If you feel that the vaccine caused your dog's condition, then you can report the Adverse Reaction Event to VMD yourself.
Go to https://www.vmd.defra.gov.uk/adversereactionreporting/report-type

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