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Enostosis-like lesions in equids: 79 cases (1997–2009)

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  • 1 Department of Clinical Studies, School of Veterinary Medicine, New Bolton Center, University of Pennsylvania, Kennett Square, PA 19348.
  • | 2 Randwick Equine Center, 3 Jane St, Sydney, NSW 2031, Australia.
  • | 3 Department of Clinical Studies, School of Veterinary Medicine, New Bolton Center, University of Pennsylvania, Kennett Square, PA 19348.
  • | 4 Department of Clinical Studies, School of Veterinary Medicine, New Bolton Center, University of Pennsylvania, Kennett Square, PA 19348.

Abstract

Objective—To evaluate equids with enostosis-like lesions (ELLs) and document the clinical and epidemiological features of this disease.

Design—Retrospective case series.

Animals—79 equids with a scintigraphic diagnosis of at least 1 ELL on ≥ 1 occasion.

Procedures—Medical records of 4,992 equids that underwent bone scintigraphy between March 1997 and March 2009 were reviewed; 78 horses and 1 pony had a scintigraphic diagnosis of an ELL. For those equids, signalment; physical, scintigraphic, radiographic, and lameness examination results; and outcome were reviewed.

Results—Of the 79 equids, 4 (5.1%) had anatomically distinct ELLs on 2 (n = 3) or 4 (1) separate occasions that caused lameness in different limbs. Thus, there were 85 ELL-related admissions to the hospital. Overall, 157 ELLs were detected. Among all equids undergoing scintigraphic examination, Thoroughbreds were more commonly and Standardbreds were less commonly affected. Older animals were more likely to have ELLs. Lameness was directly attributed to scintigraphically evident ELLs in 42 of the 85 (49.4%) admissions. The tibia (62/157 [39.5%]) and the radius (46/157 [29.3%]) were most commonly affected. The ELLs located in the humerus caused more severe lameness than did ELLs in other anatomic locations. Lameness severity was associated with radiopharmaceutical uptake intensity. Among racehorses, those with 1 ELL were more likely to return to racing than were those with multiple ELLs detected in 1 scintigraphic examination; mean interval from diagnosis to first start was 184 days.

Conclusions and Clinical Relevance—Results of this retrospective evaluation of a large group of equids with ELLs have provided a better understanding of this disease process.

Abstract

Objective—To evaluate equids with enostosis-like lesions (ELLs) and document the clinical and epidemiological features of this disease.

Design—Retrospective case series.

Animals—79 equids with a scintigraphic diagnosis of at least 1 ELL on ≥ 1 occasion.

Procedures—Medical records of 4,992 equids that underwent bone scintigraphy between March 1997 and March 2009 were reviewed; 78 horses and 1 pony had a scintigraphic diagnosis of an ELL. For those equids, signalment; physical, scintigraphic, radiographic, and lameness examination results; and outcome were reviewed.

Results—Of the 79 equids, 4 (5.1%) had anatomically distinct ELLs on 2 (n = 3) or 4 (1) separate occasions that caused lameness in different limbs. Thus, there were 85 ELL-related admissions to the hospital. Overall, 157 ELLs were detected. Among all equids undergoing scintigraphic examination, Thoroughbreds were more commonly and Standardbreds were less commonly affected. Older animals were more likely to have ELLs. Lameness was directly attributed to scintigraphically evident ELLs in 42 of the 85 (49.4%) admissions. The tibia (62/157 [39.5%]) and the radius (46/157 [29.3%]) were most commonly affected. The ELLs located in the humerus caused more severe lameness than did ELLs in other anatomic locations. Lameness severity was associated with radiopharmaceutical uptake intensity. Among racehorses, those with 1 ELL were more likely to return to racing than were those with multiple ELLs detected in 1 scintigraphic examination; mean interval from diagnosis to first start was 184 days.

Conclusions and Clinical Relevance—Results of this retrospective evaluation of a large group of equids with ELLs have provided a better understanding of this disease process.

Contributor Notes

Presented in part at the 56th Annual Convention of the American Association of Equine Practitioners, Baltimore, December 2010; and the American College of Veterinary Surgeons Annual Veterinary Symposium, Seattle, October 2010.

Address correspondence to Dr. Ahern (bahern@randwickequine.com.au).