When we raise the subject of vaccination of dogs, most people immediately think of parvovirus. This aggressive virus has been around since 1978, and causes very serious gastrointestinal disease and, without treatment, rapid death. Vaccination is highly protective and very safe. Canine distemper virus and infectious canine hepatitis virus are both still around, both rare, both extremely unpleasant to catch, and both easily prevented by vaccination.

But the disease you should be most concerned about is leptospirosis. This is caused by a bacterium, not a virus. The bacterium is found in a wide variety of host species, many of whom are quite healthy carriers. Cattle, pigs, rats, and dogs are all well recognized host species. The bacterium can be spread from animal to animal by direct transmission (eg mating, fighting), but also by indirect transmission via contaminated urine, in which it can survive in warm weather for several weeks. Contact of contaminated urine with an intact (no wound required) mucous membrane such as the gum, can result in infection. It only needs a susceptible dog to drink out of a creek that has had infected rats urinating in it, and they can become infected.

Infection leads to a fever, followed by liver and kidney damage, though the degree of damage will vary. Some are mildly affected, only showing vomiting and fever, but can progress to chronic renal failure later. Others are affected much more acutely, leading in a few days to acute renal and hepatic failure, and death.
Diagnosis is difficult, since in the first week blood tests for leptospira antibodies are often negative. Diagnosis is often based on clinical signs alone, or post-mortem histology.

Treatment involves aggressive therapy for acute renal failure, which requires several days on intravenous fluids in the clinic, plus antibiotics to kill the bacterium and try to eliminate the carrier state. Given leptospirosis is also a zoonotic (can transmit to humans) all this must be done in an isolation ward, so costs become extremely high.
Rural dogs that live rurally, or drink water from creeks, are 8 and 12 times more likely to become infected than town-based dogs.

Vaccination is a killed vaccine, and does not last long. Two doses are required initially, 3-4 weeks apart. Annual revaccination is essential, and if it has been 15 months since a last vaccine, the initial course of two injections is required.
Key points:
  • Vaccinate all your dogs: start at 9 and 12 weeks of age, then annually
  • Control rodents
  • Isolate any suspicious dogs from the others and get them to the clinic
  • Disinfect kennels regularly: use iodine-based disinfectant or diluted bleach
  • Be aware of the zoonotic potential of this disease
  • Leptospirosis is a particularly nasty illness in dogs, this is not the case in all other species. Prevention is the best way of treatment
Paul Eason BMV&S MACVSc