PIGEON FEVER IN HORSES IN THE OKANAGAN VALLEY 2010 

 



            This summer and fall we are seeing a large number of cases of a disease commonly called PIGEON FEVER.  This is a bacterial disease of horses caused by an organism called Corynebacterium pseudotuberculosis.  It is a soil organism and has nothing to do with pigeons. 

 

            The disease has it’s name because typical cases cause swellings in the pectoral area of horses making their chest look like that of a pigeon.  This disease is common in many parts of California and Colorado. We saw a few cases here in our valley in the Peachland area about twenty years ago, but no more until this year.  Within our practice clientele, we have many farms with affected horses at the present time.  The causative bacteria is a very hardy soil organism that may survive in the soil for months and may even multiply while in the soil. 

 

           We believe that biting flies carry the bacteria from the ground to the horse and the bacteria enters under the horse’s skin when the fly bites the horse. Once in the horse, the bacteria quickly multiplies causing infection in the tissue  and typically causes the development of abscesses in the subcutaneous tissues, muscle and lymph nodes. 

 

            The usual place these show up on the horse is in the underbelly, or chest area, but we have seen abscesses on the head and other places as well.  These abscesses can be superficial or deep in the muscle. In the typical case, the abscesses grow and eventually soften and burst or may be lanced when they are mature and ready. The open abscess will discharge large quantities of pus. 

 

           For the next week or two the lesion will drain yellow serum and then will begin to heal. Some cases can be more complicated, however, and may have multiple abscesses form and drain over weeks.   A small percentage of cases may develop internal abscesses and more severe health problems secondary to internal infections.

 

          So how do we handle these horses?  The simple cases develop simple abscesses that once open, drain well and only require daily cleansing.  Hot packing may help the abscesses to mature and soften and drain.  More complicated cases that develop fevers or deep abscesses that do not drain well may require pain medication and antibiotics for a number of days. 

 

          We are not exactly sure why we are seeing this disease showing up now in the Okanagan.

 

          It is likely that there has been some change in our regional environment that has favored the emergence of some species of biting fly that is spreading the disease.  Within our client list, we have many farms affected and in some cases many horses on those farms are affected. In many cases, the farms affected are isolated from other horse farms and do not have regular human traffic to and from other horse farms.  This further points towards insect transmission.

 

          The incubation period for this disease can be weeks to months, so we expect to see many more cases this fall.  Once the flies are all dead, transmission should stop.  Recovered horses should be expected to have very long immunity, possibly for life. 

 

          There is no vaccine to help prevent this disease.

 

          How can we control the spread of this disease?  This is a real challenge since soil and flies are a normal part of the horse’s environment.  As with any infectious disease, common sense would say that one should dispose of pus and discharges in a safe manner on farms that already have the disease.

 

          Fly spray and blankets may be of some benefit.  One needs to be aware that the organism is very tough and can be spread from one location to another by humans or horses moving about, but of course there is no way to keep flies from going from farm to farm.

 

         Horse traffic to and from infected farms should be avoided until well after all signs of the disease have passed.  We do not know what to expect for next summer. Quite likely we will be at the mercy of the weather conditions and the biting fly varieties present next summer.  

  Update on Pigeon Fever as of January 8, 2011    

 

     We are now seeing very few new cases.  In our practice, we do have a few stragglers carrying on trying to get rid of chronic abscesses and local infections.  We may still see the odd new one as the incubation period can be quite long, but it certainly appears that we have turned the corner as far as new cases.  In December, Alex attended some in depth educational sessions about pigeon fever at the annual American Association of Equine Practitioners meeting in Baltimore.  After attending these sessions, we are confident that in our practice we understand the science of this disease at least as far as it is understood by the veterinary profession.  That being said, however, there is still much that is not understood about transmission, spread and why it comes and goes in certain areas.

     Veterinary specialists at the B C Animal Health Diagnostic Laboratory and the Western College of Veterinary Medicine are collaborating to analyze samples and to try to shed some light on pigeon fever as it occurred in our valley this summer.  Watch this web site for updates as more information becomes available.   

 

PIGEON FEVER UPDATE February 11, 2011

 

      

     We are still seeing the very odd case.  These are all horses that have had previous abscesses and the odd new abscess shows up in another spot on the horse.  These have all been at farms that had other cases last fall.  We have not seen any new farms emerging with cases since November.

 

 

Pigeon Fever Update May 17, 2011

 

   Nothing new to report.  No new cases this spring so we are keeping our fingers crossed with the hope that we will not see more cases this summer.  

 

December 6, 2011  

 

     During the summer of 2011 we did not see any cases of pigeon fever.  This   may seem quite amazing but is typical of what often happens with this disease.