I’d be delighted if all pet owners could be experts in the field of preventive and protective animal care. Lepto vaccination falls under that category, yet even my most knowledgeable clients seem to find it a foreign and even suspicious-seeming topic. I’m giving the vaccine for this every day, but I have a real aversion to doing something for your dog that you don’t understand. So… let’s talk about lepto.

“Lepto” is short for leptospirosis, which is also doubtless a foreign-sounding word. This is a disease that has been hurting people and their animals for centuries, but even after all that time, it’s still rather poorly understood. It’s a bacterium, like Strep or E. coli, but it can’t be cultured on a Petri dish and is impossible to see under a normal microscope. When it was finally spotted in the flesh, scientists realized it was corkscrew-shaped. Perhaps knowing what it looks like will help make it real for you.

Any mammal can get lepto, including you, although some get much sicker than others. It enters through mucous membranes during licking and snuffling, which are two of the three most popular outdoor activities for dogs. Once inside, it makes a beeline for the kidney. If the kidney is compatible with this specific type of lepto (there are many varieties), it will set up a tidy little home there and begin manufacturing offspring, which are unleashed into the environment with every drop of urine. Rats and raccoons are an excellent match for lepto, and because these two animals adore humans’ trash, they’re crowding up into your backyard every time the sun goes down. And they’re bringing urine.

If, instead, the kidney is found to be incompatible (say, a raccoon lepto moves into a dog kidney), the new tenants act like monsters and make no effort to take care of the place. In a week or two, the kidney is burned to the ground, and the dog is in a fight for his life. Although lepto is treatable, it’s very difficult to make a diagnosis in time. There’s no reliable set of symptoms to define this disease, just a mashup of random troubles from every corner of the patient. Dogs that have lepto might look exactly like the ones that have parvovirus, until they start looking like they have pneumonia instead, and then they start looking like a dog that ate poison and may also resemble a dog with a fungal infection. But not necessarily in that order.

Although lepto thrives best in moist spots on the ground, it can survive just about anywhere. Its territory is expanding steadily, so that no dog is safely out of reach. It’s not just for “outdoorsy” types, either. The most commonly hospitalized lepto patient is, in fact, the Yorkshire terrier. Again, no dog is safely out of reach. Next time you’re in the clinic and the lepto vaccine is mentioned, you won’t have to tip your head quizzically to the side and try to control your eyebrows. Just hit me with the finger guns and say, “Lepto… yeah, of course. The corkscrew.”

Dr. M.S. Regan