Prevention of renal infection and urinary shedding in dogs by a Leptospira vaccination.

Prevention of urinary shedding of Leptospira interrogans spp. by chronically infected dogs remains a key objective of the vaccination in dogs against leptospirosis which is a zoonotic disease. An inactivated bivalent vaccine composed of Leptospira interrogans serovars icterohaemorrhagiae [L. icterohaemorrhagiae] and canicola [L. canicola] bacterins was tested for its ability to protect puppies against a challenge exposure with L. icterohaemorrhagiae. The vaccine was administered twice at a 3-week interval to six puppies aged from 8 to 9 weeks. Six other puppies were used as unvaccinated controls. All puppies were challenged 2 weeks after the second vaccine injection by intraperitoneal (IP) administration of L. icterohaemorrhagiae (day 0). Clinical signs, haematological and biochemical changes and evidence of Leptospira in blood, urine and kidney were monitored for 4 weeks after the challenge exposure (days 0-28). Puppies were euthanised on day 28 for post-mortem and histological examinations of liver and kidney. Control group presented clinical pictures of severe or subclinical infection. One dog developed severe clinical signs (hypothermia, depression, anorexia, abdominal pain, dehydration, icterus, weight loss) and died on post-infection day (PID) 7 due to an acute renal failure. Gross and microscopic lesions were in accordance with this clinical pattern. In the five remaining control dogs, the challenge exposure induced mainly a systemic infection including leptospiraemia, leptospiruria and renal carriage. The vaccinated group remained healthy throughout the study period. In conclusion, immunisation with a Leptospira vaccine was shown to protect dogs against symptomatology and leptospiraemia, urine shedding and renal infection.