Leptospira bacterins may protect against two or four of the most common sub- species of bacteria that cause leptospirosis. The two-serovar bacterin may be incorporated into a DHPP shot given at 12 weeks of age and again at 14 to 16 weeks of age. Many veterinarians give the four-serovar bacterin as a separate injection as early as 12 weeks and then two to three weeks later.
Leptospira bacterin has been responsible for 70 percent of post-vaccination DHLPP anaphylactic shock reactions. Toy breeds and puppies younger than 12 weeks old seem to have the highest rate of reactions to this bacterin. In addition, the two-serovar vaccines do not protect against the two species that are currently responsible for the majority of cases. Accordingly, routine vaccination is now considered optional. It is still indicated in areas where the risk of the disease is greater than the risk of the vaccination. Leptospirosis is not contained in all the combination vaccines and can be given separately.
Both Fort Dodge and Pfizer have vaccines that now cover all four of the primary serovars of leptospirosis. These are subunit vaccines, so there is less chance of an allergic reaction to the vaccine. With leptospirosis cases on the rise, this vaccine may be recommended in more areas. Immunity following vaccination averages about four to six months. Therefore, if vaccination is important, it may be advisable to revaccinate every six months. Discuss this with your veterinarian.