EQUINE | African Horse Sickness
EQUINE | African Horse Sickness
• 0.25mg / kg pimobendan po BID or 11 µ g / kg digoxin * BID for 7 days - continue with pimobendan or digoxin for 1 week in conjunction with strict rest .
The idea behind the cardiac specific drugs is to support the horse during the period of acute heart failure while the body mounts a response to the virus . From our preliminary data , cardiac troponin and heart function start to improve within 3-4 days of infection and by 1-2 weeks post infection they have normalised ( unpublished data ). This suggests that intensive treatment of horses with acute AHS for 1-2 weeks using cardiac specific drugs has the potential of improving survival rates in the short term . In addition , all of these drugs can be administered in the field , and do not require for the horse to be hospitalized . This provides an added advantage , as moving horses with AHS is associated with an increased risk of sudden death 2 , presumably due to terminal cardiac arrhythmias .
For the reasons that have already been discussed , water should not be withheld in cases of AHS and furosemide should not be administered long term without an ACE inhibitor . The exception to this would be peracute cases with severe pulmonary oedema . In these cases , furosemide should be given immediately in high doses ( 1-2mg / kg ) and can be repeated every 4-6 hours to reduce pulmonary oedema while the horses is stabilized and you get an opportunity to administer the ACE inhibitors and positive ionotrope . Fluids if given must be given judiciously and only if necessary . Additional treatment , including the use of colloids or hypertonic saline should be considered on a case by case basis .
Further research and disclaimer
The recommendations for treatment outlined in this article are based on a small pilot study and a successful outcome in a small number of clinical cases in which the treatment protocol has thus far been implemented .
We are in the process of designing a large multi-centre randomized clinical trial in order to determine the efficacy of this treatment protocol in clinical cases with AHS . Horses will be sourced from veterinary practices across South Africa , and will be included in the study after confirmation of their eligibility and written consent from the owner has been obtained .
The use of this treatment protocol at this time is therefore at the discretion of the attending veterinarian and should only be considered in conjunction with sound clinical judgment and an understanding that there is currently little evidence for its efficacy . In addition , due consideration should be given to the potential of toxicosis in horses that are treated with digoxin and careful therapeutic monitoring is advised . Alternatively , pimobendan should be used .
If you would like to be involved in this study , please contact mhewetson @ rvc . ac . uk for further information .
References 1 . Micintosh BM . Immunological types of horsesickness virus and their significance in immunization Onderstepoort Journal of Veterinary Research 1958 ; 27:465-539 . 2 . Coetzer JAW , Guthrie AJ . African Horse Sickness . In : Tustin RC , Coetzer JAW , eds . Infectious diseases of livestock , 2nd ed . Cape Town : Oxford University Press 2004:1231-1246 . 3 . Mellor PS , Hamblin C . African horse sickness . Veterinary research 2004 ; 35:445-466 . 4 . Theiler A . African horse sickness ( pestis equorum ). Scientific Bulletin 1921 ; 19:1-29 . 5 . de Vos CJ , Hoek CA , Nodelijk G . Risk of introducing African horse sickness virus into the Netherlands by international equine movements . Preventive veterinary medicine 2012 ; 106:108-122 . 6 . Carpenter S , Wilson A , Mellor PS . Culicoides and the emergence of bluetongue virus in northern Europe . Trends in microbiology 2009 ; 17:172-178 . 7 . Purse BV , Carpenter S , Venter GJ , et al . Bionomics of temperate and tropical Culicoides midges : knowledge gaps and consequences for transmission of Culicoides-borne viruses . Annual review of entomology 2015 ; 60:373-392 . 8 . Alba A , Casal J , Domingo M . Possible introduction of bluetongue into the Balearic Islands , Spain , in 2000 , via air streams . The Veterinary record 2004 ; 155:460-461 . 9 . Maurer FD , McCully RM . African Horse Sickness , with emphasis on pathology . American Journal of Veterinary Research 1963 ; 24:235- 266 . 10 . Wohlsein P , Pohlenz JF , Davidson FL , et al .
52 • Equine Health Update •