Efficacy of intramuscular tylosin for the treatment and control of porcine proliferative enteropathy caused by Lawsonia intracellularis

This double-blind study investigated the efficacy of injectable tylosin (Tylan 200 injection, Elanco Animal Health, Indianapolis, IN) for the treatment and control of porcine proliferative enteropathy caused by Lawsonia intracellularis using a mucosal challenge model. Intramuscular (IM) tylosin was compared with sterile tylosin injection carrier (negative control). IM treatments (1 mL/22.5 kg [50 lb body weight; 4 mg/lb body weight]) were administered to two groups of pigs twice daily for 3 consecutive days, commencing 14 days after L. intracellularis challenge. Clinical signs were evaluated in 80 pigs each day for 14 days after treatment was initiated. Necropsies were performed on all pigs 14 days after treatment to evaluate gross and microscopic intestinal lesions. The challenged pigs had a positive treatment response to injectable tylosin compared with negative controls based on improvements in clinical signs, fecal polymerase chain reaction incidence on days 7 and 14, gross and microscopic intestinal lesions, average daily weight gain, and individual pig weight variation.

Protective role of maternal antibodies against Haemophilus parasuis infection

OBJECTIVE

To evaluate the impact of maternal antibodies after challenge exposure of baby pigs with a homologous serovar of Haemophilus parasuis.

ANIMALS

7 gilts and their litters from a high health status farm.

PROCEDURE

Gilts were vaccinated twice with a commercial bacterin that contained H parasuis serovar 4 and 5 or, as a control, adjuvant only. A group of pigs was also vaccinated similarly before challenge exposure. After early and late challenge exposure at 3 and 4 weeks, respectively, all pigs from vaccinated gilts were evaluated for clinical signs of infection, lesions, and antibody titer.

RESULTS

All pigs coming from control gilts had severe signs of H parasuis infection. Macroscopic lesions included polyserositis and pneumonia, and bacteriologic examination confirmed H parasuis as the etiologic agent. Vaccinated pigs born to vaccinated gilts did not have clinical signs of disease. However, some vaccinated pigs born to control gilts had signs of nervous system dysfunction and lameness. There was no difference in lesion scores between early or late challenge exposure, but lesions scores for pigs from vaccinated and control gilts were different (P < 0.01).

CONCLUSIONS

Under these experimental conditions, immune-naive and vaccinated pigs from vaccinated gilts were protected against systemic lesions when challenge exposed with a virulent strain of H parasuis.

CLINICAL RELEVANCE

Vaccination of the gilt and pigs protects the latter from polyserositis, but results are not different from those for nonvaccinated pigs from vaccinated gilts. Maternal antibodies did not seem to interfere with vaccination of pigs at 1 and 3 weeks of age.