A study conducted by Goldstein et al¹ reviewed leptospirosis cases seen at referral centers in New York State and identified the differences in clinical or clinicopathologic aspects of the disease among different suspected infecting serogroups.

Study Design

Medical records at the Cornell University Hospital for Animals (CUHA) and the Animal Medical Center (AMC) in New York City were reviewed to identify dogs diagnosed with leptospirosis from September 1996 to August 2002. The records of 55 dogs met the inclusion criteria for the study: 42 from CUHA and 13 from AMC. The suspected infecting serogroups included 21 occurrences of L. grippotyphosa, 12 of L. pomona, 6 of L. autumnalis, 5 of L. bratislava, 2 of L. hardjo, and 1 of L. canicola.

Results

Key Learnings

Leptospira serogroup L. pomona caused more severe renal disease and was associated with a poorer prognosis compared with disease caused by other serogroups.

2. Duration Of Immunity In Dogs Vaccinated Against Leptospirosis With A Bivalent Inactivated Vaccine

Klaasen et al² conducted a study that assessed the duration of immunity in dogs attainable with a commercial inactivated bivalent leptospirosis vaccine.

Study Design

Young dogs were vaccinated twice followed by challenge with Leptospira interrogans serovar L. canicola or L. interrogans serovar L. icterohaemorrhagiae 5 weeks, 27 weeks or 56 weeks after the second vaccination. For assessment of duration of immunity, titers of agglutinating serum antibodies were measured before and after the challenge, and the effects of challenge on a variety of parameters were determined including reisolation of challenge organisms from blood, urine, and kidney.

Results

Both challenge strains induced a generalized infection in control dogs, the L. canicola strain being the most virulent. From the results with different parameters it appeared that the 2 vaccinations induced a high rate of protection from generalized infection with L. canicola and L. icterohaemorrhagiae at 5, 27, and 56 weeks after the second vaccination. Additionally, after 56 weeks, a high level of immunity still existed against renal infection with serovar L. canicola and, as a consequence, urinary shedding of the serovar L. canicola bacteria was demonstrated.

Key Learnings

It was concluded that using the above mentioned vaccine schedule, a bivalent inactivated vaccine can help provide up to 1 year of immunity against both Leptospira serovars.

3. Adverse Events Diagnosed Within 3 Days Of Vaccine Administration In Dogs

This study conducted by Moore et al³ was designed to determine the incidence rates and potential risk factors for vaccine-associated adverse events (VAAE) diagnosed within 3 days of administration in dogs.

Study Design

Electronic records from January 1, 2002, through December 31, 2003, were searched for possible VAAEs (non-specific vaccine reaction, allergic reaction, urticaria, or anaphylaxis) diagnosed within 3 days of vaccine administration. Information included age, weight, sex, neuter status, and breed. Specific clinical signs and treatments were reviewed in a random sample of 400 affected dogs. The association between potential risk factors and a VAAE was estimated by use of multivariate logistic regression.

Results

Four thousand six hundred seventy-eight adverse events (38.2/10,000 dogs vaccinated) were associated with administration of 3,439,576 doses of vaccine to 1,226,159 dogs. The VAAE rate decreased significantly as body weight increased. Risk was 27% to 38% greater for neutered vs sexually intact dogs and 35% to 64% greater for dogs approximately 1 to 3 years old vs 2 to 9 months old. The risk of VAAE significantly increased as the number of vaccine doses administered per office visit increased; each additional vaccine significantly increased risk of an adverse event by 27% in dogs ≤10 kg (22 lb) and 12% in dogs >10 kg (22 lb).