Posted by Dr. Steve Dudley on June 16 2004 09:32
Swine Newsletter 2nd Quarter 2004
Swine Influenza virus has caused problems in the swine industry for over 50 years. The cause of SIV is a virus that has its origins in the bird population and also is somewhat related to the human strains of influenza.
SIV is found worldwide and causes high fevers, increased respiratory distress and a severe characteristic barking cough. When SIV hits a group of pigs, it causes over 80% of the group to have severe clinical problems and it is highly contagious. SIV is transmitted through contact with infected pigs that are viremic, or shedding the virus. In addition, aerosol spread can occur. SIV tends to be primarily a problem in swine dense areas where alot of pigs are raised.
The classic SIV is categorized as H1N1. The H1N1 represents outside characteristics of the virus that cause it to stimulate certain immunities. A new strain called H3N2 has been present for over 3 years. Recently H1N2 and other strains continue to be identified. Swine Influenza virus as the ability to mutate and change its outside structure. Many laboratories are able to genetically sequence to determine the genetic material and make up of SIV. At Veterinary Medical Center and Newport Laboratories we are able to do this in house to allow each SIV isolate to be genetically determined. This allows us to compare and determine if commercial vaccines will be effective and or if autogenous, farm specific vaccines would be the best preventative program.
The industry continues to agree that strain differences have been part of the frustrations associated with SIV. Swine influenza vaccines are effective if the correct strain is identified and utilized. We strongly recommend that all sow herds in SW Minnesota and NW Iowa be vaccinated with a dual H1N1 and H3N2 swine influenza vaccine. This should be given on a semi-annual to all sow herd to help prevent the clinical outbreak of swine influenza. In addition, many finisher flows will benefit from SIV.
The most costly part of an influenza outbreak is not the death loss but the loss in pounds of pork produced in the finishers. Pigs can be set back 10 days to 2 weeks with minimal growth during that time period. Once an outbreak occurs, the treatment needs to utilize Temp Down or Temp Relief. These products help to lower the temperature and help the pigs feel better. In addition we use an expectorant that helps to lower the cough and an antibiotic to control secondary bacterial infections.
The most important part of a good SIV program requires an adequate diagnosis. Nasal swabs of highly feverish animals can be taken to determine if SIV is in the pig. Once the virus is isolated we can do the genetic testing to determine the best control program.
If you are seeing severe coughing or off-feed animals in your sow herd or finishers give us a call so we can help you identify this chronic problem.