High temperatures and high humidity: be on guard against Haemophilus parasuis disease
As temperatures rise and humidity increases, the incidence of bacterial diseases in pig herds will rise, and there is all the more need to be on guard against Haemophilus parasuis infection. Haemophilus parasuis infects only pigs and can affect young pigs from 2 weeks to 4 months of age, mainly causing disease around weaning and during the nursery stage, usually seen in pigs of 5 to 8 weeks of age, with an incidence rate of 10% to 15%, and in severe cases the mortality rate can reach 50%.
Acute cases often first occur in pigs in good body condition. Affected pigs have fever (40.5 to 42°C), depression, reduced appetite, difficulty breathing, abdominal breathing, red or pale skin, purplish ear tips, subcutaneous edema of the eyelids, slow walking or unwillingness to stand, swelling of the carpal and tarsal joints, and before death lie on their side or paddling with the limbs. Sometimes they die suddenly without obvious symptoms.
Chronic cases are mostly seen in nursery pigs. Affected pigs have reduced appetite, coughing, difficulty breathing, rough coat, weakness of the limbs or lameness, and poor growth, until they die of exhaustion.
Judging from actual application results, florfenicol, cephalosporins, amoxicillin, ampicillin, gentamicin and potentiated sulfonamides and others have a certain therapeutic effect on this disease, while most strains are resistant to erythromycin, aminoglycosides and lincomycin.
In severe outbreaks of Haemophilus parasuis disease, antibiotic treatment results are unsatisfactory. Once clinical symptoms have appeared, injectable treatment of affected pigs with large doses of the above sensitive antibiotics by means other than oral administration should be adopted immediately, dosing once every 6 to 8 hours, while at the same time other pigs in the whole herd should be given preventive treatment.
The therapeutic effect of this disease is poor, so in actual pig farm production practice, preventing outbreaks of this disease is the best policy. For example, after piglets are weaned, add to the feed tiamulin 100 (unit: mg/kg, the same below) + chlortetracycline 300 + amoxicillin 250, or tiamulin 100 + florfenicol 80.
On pig farms with severe Haemophilus parasuis disease, the herd may be immunized when necessary; autogenous vaccines have a certain preventive effect; where conditions do not allow, a multivalent inactivated Haemophilus parasuis vaccine may also be used for immunization. Sows: for first immunization, first dose 40 days before farrowing, second dose 20 days before farrowing. For previously immunized sows, one immunization 30 days before farrowing is sufficient. On pig farms seriously threatened by this disease, piglets should also be immunized; piglet immunization is generally arranged between 7 days and 30 days of age, 1 milliliter each time, and preferably repeated once 15 days after the first immunization, with an interval of more than 10 days between the second immunization and the onset of disease.
Strengthen feeding management and environmental disinfection, reduce all kinds of stress; during an epidemic, pig farms with the necessary conditions may temporarily avoid mixing piglets at weaning and isolate affected pigs together in the same pig house. Before and after weaning, transferring, mixing or transporting pigs, add some anti-stress drugs such as vitamin C to the drinking water, and at the same time add the above recommended drug combinations to the feed, which can effectively prevent the occurrence of this disease.