title: Acquired equine polyneuropathy in Norway and Sweden: a clinical and epidemiological study.
abstract: BACKGROUND
  Acquired equine polyneuropathy (AEP, also known as 'Scandinavian knuckling syndrome'), is a serious disease of unknown aetiology, which emerged clustering in horse farms in Sweden, Norway and Finland in the 1990s. Clinical and epidemiological data regarding the syndrome are scarce.
  
  
  OBJECTIVE
  To describe the clinical and epidemiological findings and outcome in outbreaks of AEP and compare risk factors in affected and unaffected horses on affected farms in Norway and Sweden during 2007-2009.
  
  
  METHODS
  Neurological examinations were performed and data collected regarding demography, usage, turning-out, feeding, prophylactic strategies and long-term outcome.
  
  
  RESULTS
  Thirteen affected farms with 157 horses of various breeds, of which 42 were AEP cases, were studied. Typical digital extensor dysfunction and knuckling of pelvic limbs were noted in 34 definitive cases. Eight additional plausible cases had a severe, acute course of neurological disease. There were no signs of brain orcranial nerve dysfunction. Cases occurred from December to April, with new cases emerging within 100 days of the index case. Affected and unaffected horses were fed wrapped forage. Prevalence for AEP was 27% and case fatality 29%. The median duration of AEP in survivors was 4.4 months (1-17 months). Survivors returned to full work within 19 months (median 6.6 months). Acquired equine polyneuropathy was less prevalent in horses aged > 12 years and young horses had a higher chance of survival than older horses. Management factors did not differ between affected and unaffected horses.
  
  
  CONCLUSIONS
  Acquired equine polyneuropathy is a potentially fatal neurological disease characterised by pelvic limb knuckling. Surviving horses returned to normal function after a long period of rest. Cases were clustered in farms during the winter/spring season. Wrapped forage was used in all farms.
  
  
  CONCLUSIONS
  The results provide valuable insights into the dinical examination, handling and prognosis of cases of AEP, an emerging neurological disease of unknown aetiology in horses.
authors: Department of Animal Health and Antimicrobial Strategies SVA, National Veterinary Institute, Sweden. gittan.grondahl@sva.se
authors: G
authors: G
authors: Gröndahl
authors: S
authors: S
authors: Hanche-Olsen
authors: J
authors: J
authors: Bröjer
authors: C F
authors: CF
authors: Ihler
authors: K Hultin
authors: KH
authors: Jäderlund
authors: A
authors: A
authors: Egenvall
mesh_terms: D000818:Animals; D003625:Data Collection; D004196:Disease Outbreaks; D005260:Female; D006734:Horse Diseases / Q000453:epidemiology* / Q000473:pathology; D006736:Horses; D008297:Male; D009664:Norway / Q000453:epidemiology; D011115:Polyneuropathies / Q000453:epidemiology / Q000473:pathology / Q000662:veterinary*; D011795:Surveys and Questionnaires; D013548:Sweden / Q000453:epidemiology