The American Animal Hospital Association considers the leptospirosis vaccine a “non-core” vaccine for dogs. That is, they see it as optional. But is it optional for your particular pet? Cummings School clinical professor Mary Labato, DVM, DACVIM, says that “at Tufts, we recommend lepto vaccination for all dogs. Besides the fact that leptospirosis is potentially fatal, the cost of treating this preventable disease can range into the thousands of dollars, with the high end including those dogs that require dialysis” because of kidney failure. “In fact,” Dr. Labato adds, “lepto cases account for approximately 50 percent of the dogs we dialyze each year. It can be a tough conversation when an owner who has potentially spent thousands of dollars to treat her dog for lepto finds out that this disease could have been prevented with a simple vaccination.”
Just what is leptospirosis?
Simply put, leptospirosis is a life-threatening bacterial infection that affects the liver and kidneys. The bacteria, which are spiral-shaped and wriggle about in a spinning motion, thrive in animal urine, including the urine of raccoons, skunks, rats, and other rodents that your dog might like to sniff and thereby infect himself. (The animals that shed the bacteria in their urine are not usually ill. They are simply carriers of the disease-causing microorganisms.) Particularly common in New England, the West Coast, and the South, the offending bacteria also colonize in warm, moist environments: think stagnant puddles of water, ponds, and the like. But they like to multiply in mud, too. In addition, lepto bacteria can enter an animal’s system through a bite wound or through a dog’s eating or licking infected materials, say, a stick on which another animal has urinated or even some interesting-smelling soil.
Veterinarians have tended to see cases in late summer and fall. The hot weather has cooled, the environment becomes more moist again, and both pet dogs and wildlife are out and about because the weather is not extremely hot or extremely cold. For obvious reasons, dogs who run free in the woods with ponds and puddles and lots of wildlife are at special risk. But these days, with the suburbs and undeveloped areas pushing closer and closer together, even dogs who live in tract housing and other close-quarter environments can be prone.
Weather isn’t a completely reliable indicator of proneness, either. Last summer, Dr. Labato says, “despite the hot weather, we saw many more cases of leptospirosis than usual. Normally, we see very few cases in the summer.”
If your dog gets sick, it means the leptospira bacteria have spread rapidly through his bloodstream. The incubation period between initial infection and actual symptoms of illness ranges from a couple of days to a little less than a month. Some of the more typical signs include loss of appetite, fever, depression, severe muscle pain, stiffness or difficulty moving about, shivering, and overall weakness that keeps getting worse. Dehydration can occur as well, as a result of vomiting and diarrhea. If the disease is severe enough, there may be conjunctivitis and difficulty breathing and finally, an assault on the liver and kidneys because of powerful toxins the bacteria produce, which leads to the failure of those organs. Some dogs, mainly young ones, will die suddenly before a lot of these signs even occur. Unfortunately, a lot of the signs are non-specific and are attributable to any number of illnesses, so it is not uncommon to miss the diagnosis on the first examination.
To help make a determination, along with considering clinical signs, a veterinarian may also order some laboratory tests on a dog’s urine and blood. They can help detect abnormalities in the blood (such as an elevation in white blood cells or liver enzymes), and in the urine (such as an elevation in protein). Again, though, these are not surefire bets for a diagnosis. Hepatitis, herpes, autoimmune disease, and some poisonings can produce the same blood and urine findings. Fortunately, there is a leptospirosis PCR test that is a sensitive marker for the disease, and results can be obtained rapidly. But it’s not usually the first test a vet will reach for, so time is lost if leptospirosis is indeed the problem.
The silver lining here is that the treatment of leptospirosis is more straightforward than the diagnosis, especially if the disease has not yet gotten severe. Consider that many common antibiotics will kill leptospira bacteria, including penicillin, tetracycline, and erythromycin. Doxycycline does double duty because it tends to help prevent dogs from becoming silent, symptomless carriers of the disease after their recovery.
Dogs who have become quite sick are going to need more intensive therapies. For instance, some may need medications to decrease vomiting, and perhaps intravenous fluids to correct dehydration. Aggressive fluid therapy also helps flush a dog’s kidneys and in that way is thought to help protect them from sustaining permanent damage. (If the dog’s kidneys have shut down by the time the pet is undergoing treatment, dialysis may be the only way to go to keep the animal alive.)
Note that many dogs do make a full recovery. But some go on to develop chronic kidney failure or chronic active liver disease in the form of hepatitis. Those conditions are not curable.
Back to the vaccination question
So should you get your dog an annual leptospirosis vaccination?
Well, you need to consider that veterinarians do report various reactions to lepto vaccines, perhaps more than they do for other vaccines. These include pain at the injection site, facial swelling, hives, and in rare cases, a life-threatening anaphylactic reaction. You can’t predict ahead of time which dog will experience which reaction, if any.
It’s important to know, too, that while the lepto vaccines protect against up to four kinds of leptospirosis bacteria — canicola, grippotyphosa, icterohemorrhagica, and pomona — there are about 15 kinds that can potentially spell trouble for dogs. That is, a vaccination is not a full-on guarantee that your dog will not become infected.
Still, on balance, the reasons to vaccinate outweigh the reasons not to — certainly in areas where there are seasons of moist weather and moderate temperatures.
Consider, first of all, that advances in vaccine technology have reduced the rate of adverse reactions. For one of the lepto vaccines that was introduced in 2005, the adverse reaction rate reported has gone down to 1.5 cases per 10,000 doses. That’s a chance of 0.015 percent.
In addition, the most common lepto bacteria that cause illness in dogs are the ones for which vaccines exist. Getting the shot dramatically reduces the odds that a dog will come down with leptospirosis.
Finally, there is lepto’s zoonotic potential to consider. That means it can cross species. Your dog can give it to your cat, your children, or to you. You may not think of yourself as ever touching your dog’s urine, and chances are you don’t, but in gardening, curbing your dog, or even lifting your dog into your arms from his bottom, you can potentially come into contact with the offending bacteria shed when your pet voids. If your dog gives it to your cat, the litterbox becomes a breeding ground for leptospira. And so on. In other words, there are ways, however insidious, for the microorganisms to make their way from your dog to you. And even if your dog doesn’t become sick and is simply a carrier, other animals in your household who are infected could become ill.
“One challenge I see when talking with veterinarians about leptospirosis vaccination is that they perceive the incidence of the disease is low,” Dr. Labato says. Part of the reason for that is “the fact that lepto is so good at mimicking other diseases and conditions. Also, dogs that are infected and present with mild clinical signs are often treated and recover without ever having a lepto diagnosis. But two winters ago, “we had over 123 cases from 77 different locations throughout the region, and I’m sure that was just the tip of the iceberg.”
The bottom line: it’s worth discussing with your vet the advisability of getting your dog a yearly lepto vaccine. Not every single dog should get one, but many more should be getting it than currently are.