title: Epiphyseal cartilage canal blood supply to the distal femur of foals.
abstract: BACKGROUND
  The developmental pattern of the cartilage canal blood supply to epiphyseal growth cartilage has been linked to osteochondrosis (OC) in the tarsus of foals. This pattern has not yet been described in the distal femur, another site frequently affected by OC.
  
  
  OBJECTIVE
  To describe the developmental pattern of the blood supply to the distal femoral epiphyseal growth cartilage in 8 Standardbred foals age 0-7 weeks.
  
  
  METHODS
  One foal was sacrificed weekly from birth to age 7 weeks (n=8) to undergo a barium perfusion procedure to demonstrate vessels within cartilage canals of one hindlimb. The distal end of the femur was cleared in methyl salicylate and perfused vessels were studied in the intact bones. Each distal femur was then sawed into 5 mm thick slabs in the transverse plane, and the slabs decalcified and radiographed. Finally, the lateral trochlear ridge was separated from each slab and examined histologically.
  
  
  RESULTS
  The cartilage canal blood supply regressed with increasing age, but several regions remained vascularised in the oldest foal at age 7 weeks. Vessels arose from perichondrial and subchondral arterial sources, and coursed perpendicular or parallel to the ossification front. The midsection of parallel vessels became incorporated into the ossification front during growth. Anastomoses formed and vessels within the distal portion of canals with an original perichondrial source shifted to use subchondral vessels as their arterial source. Both parallel and perpendicular vessels therefore traversed the ossification front to enter cartilage canals. No histological lesions were observed in sections from any of the foals.
  
  
  CONCLUSIONS
  The same anatomical feature (traversing the ossification front to enter cartilage canals) reported to render vessels vulnerable to failure in the tarsus was also present in the distal femur of foals.
  
  
  CONCLUSIONS
  OC may occur by the same pathogenetic mechanism in the distal femur as in the tarsus of foals.
authors.affiliation: The Norwegian School of Veterinary Science, Department of Companion Animal Clinical Sciences, Section for Equine Medicine and Surgery, Post Box 8146 Dep., N-0033 Oslo, Norway.
authors.forename: K
authors.initials: K
authors.lastname: Olstad
authors.forename: B
authors.initials: B
authors.lastname: Ytrehus
authors.forename: S
authors.initials: S
authors.lastname: Ekman
authors.forename: C S
authors.initials: CS
authors.lastname: Carlson
authors.forename: N I
authors.initials: NI
authors.lastname: Dolvik
mesh_terms: D000375:Aging; D000818:Animals; D000831:Animals, Newborn; D002358:Cartilage, Articular / Q000098:blood supply* / Q000473:pathology; D005260:Female; D005269:Femur / Q000098:blood supply* / Q000473:pathology; D006132:Growth Plate / Q000098:blood supply* / Q000473:pathology; D006734:Horse Diseases / Q000473:pathology / Q000503:physiopathology*; D006736:Horses; D008297:Male; D010007:Osteochondritis / Q000473:pathology / Q000503:physiopathology / Q000662:veterinary*; D015995:Prevalence; D012039:Regional Blood Flow; D015424:Reperfusion / Q000662:veterinary; D016896:Treatment Outcome