by John V. Ioia, MD, PhD

Infection & Disease: Reprinted from AKC Gazette Magazine, September 2017

Sometimes you plan an article and sometimes one just drops in your lap.  For the forty-plus years that we have been raising, showing and breeding dogs the discussion with our veterinarians about Lepto (Leptospirosis) vaccination went as follows: Do your dogs run in or around stagnant water, areas frequented by vermin, rats, waterfowl, etc.?  The answer: Of course not.  Then you really don’t need to inoculate.  Plus the vaccination may be dangerous and is ineffective against all strains of the disease.  All of this seemed reasonable.  How then are some city dogs becoming ill and even dying from Leptospirosis and should we rethink our protocols?

May I start by saying that I am no expert in Leptospirosis and have now reconsidered my approach to this disease and its prevention?  Cavalier King Charles Spaniel and Boxer Breeder-Judge Stephanie Abraham authored what I consider to be the best article for the pet owner, breeder and exhibitor.  It’s entitled “Losing Harry Arthur” and chronicles the loss of a beloved Cavalier pup living in Boston.  It was printed in the American King Charles Spaniel Club publication, The Royal Dispatch, Winter 2014, Volume 11, Issue 1.

How could a toy dog living in an upscale neighborhood acquire Lepto?  It’s rather simple; the common vector is the rat, rat droppings, rat urine or rodents that have contact with them.  Before you think “Not my neighborhood or not my dogs,” think again.  Consider the local mall, shopping center, fast food joint, restaurant, apartment complex and dumpsters.  Have you noticed those black boxes you see along the outer walls?  Those are rat traps.

Leptospirosis is caused by bacteria of the Leptospira genus, a spiral-shaped mobile little bacterium with a hooked-shaped end that resembles the bacteria that causes Lyme’s Disease and Syphilis.  It is Zoonotic, meaning that it can be spread between animals, including your dog and you.  Look up Weil’s Disease or Rat Fever.  Leptospirosis was once a disease of rural dogs but is increasingly seen in cities due to urbanization of rural areas and increased contact with raccoons, skunks, opossums, and rodents.  Dogs typically became infected by drinking or swimming in water contaminated with Leptospira organisms.  Since the bacteria enter the host (dog) though mucosal membranes or breaks in the skin, it can be picked up by simply walking over wet contaminated areas.

Leptospires spread throughout the dog’s body, reproducing in the liver, kidneys, central nervous system, eyes, and reproductive system.  After the initial infection, fever and other symptoms develop, but these may resolve with a rise of antibodies.  This may clear the spirochetes from most of the system.  The extent to which this bacterium affects the organs will depend on your dog’s immune system and its ability to fully eradicate the infection.   Lepto can lead to liver and renal failure.  Leptospira can remain in the kidneys, reproducing there and infecting the urine.  Infection of the liver or kidneys can be fatal for animals if the infection progresses.  Younger animals with less developed immune systems are at the highest risk for severe complications.  Leptospirosis has re-emerged as a clinical disease in North America and has become a common cause of acute renal failure in many areas of the US.  Similar to dogs, when humans are infected children are most at risk of acquiring the bacteria from an infected pet.

Signs of Leptospirosis may include fever, shivering, muscle tenderness, reluctance to move, increased thirst, changes in urination, dehydration, vomiting, diarrhea, loss of appetite, lethargy, jaundice, or painful inflammation of the eyes. The disease can cause kidney failure with or without liver failure. Dogs may develop lung disease and have difficulty breathing. Leptospirosis can cause bleeding disorders, with blood-tinged vomit, urine, stool or saliva; nosebleeds; and petechiae visible on the gums, mucous membranes or skin. Affected dogs can also develop swollen legs or accumulate excess fluid in their chest or abdomen.

A major problem with Leptospirosis is that in the early or mild stages it may be misdiagnosed as gastrointestinal problem or maybe Parvo.  Without an “Index of suspicion” the infected pup is doomed.  Therefore, prevention is key.  So why aren’t more dogs vaccinated?  We should explore some of the misconceptions.

The first of which, that Lepto is rare in our communities has already been exposed.  In fact, Lepto is endemic in many larger cities.  Remember those rats.

The second and most common misconception that I have heard is how dangerous the Leptospirosis vaccine is.  While no vaccine is 100% safe and older vaccines may have had their issues, the newest vaccine is safe and effective with about 1.1% adverse effects.  When we say new, we speaking of a killed vaccine offered by Merial and Fort Dodge in 2004.

Another argument voiced against vaccination is that the vaccine can’t protect your pet against all the various strains of Lepto, so why bother?  The reality is that most if not all Lepto is cased by four strains (serovars) and the new vaccine is effective against these.  Most experts do recommend that the Leptospirosis vaccine be administered alone and not along with other inoculations.  It should be administered at about 4 months and a repeat booster is required in about another 3-4 weeks.  Also, it must ne administered annually or when titers recede.  So there is expense and inconvenience but consider the heartache and expense of caring for and losing your precious dog.  Dogs that survive the initial infection will have markedly shortened lives due to renal or hepatic involvement.

So you be the judge.  I have already made my decision.

Suggested Reading:

Losing Harry Arthur, by Stephanie Abraham: The Royal Dispatch, Winter 2014, Volume 11, Issue 1.  American Cavalier King Charles Spaniel Club


“In a significant move, veterinary health authorities have updated the core vaccine recommendations for dogs to now include the leptospirosis vaccine. This update is particularly important for dog breeders, who play a crucial role in the health and well-being of future generations of dogs…”