Prospective study of blackthorn injury and synovitis in 35 horses

Abstract

SummaryThe objective of this prospective clinical study was to investigate the cause and describe the presentation, diagnosis, treatment techniques and outcome of Prunus spinosa (blackthorn) injury and synovitis in the horse. In all cases presented with blackthorn injury and synovitis, surgical treatment was performed within 24 h, using a two‐stage procedure: 1‐Perisynovial technique using ultrasound guided electrosurgical dissection; 2‐Endoscopic technique. The diagnosis was confirmed by retrieval of black plant material from or close to the affected synovial structure. Mean lameness score on presentation was 4/5 (range 1–5). The most commonly affected structures were extensor tendon sheaths (12/35) and fetlock joints (11/35). All cases had thorn material removed, 80% had thorn material removed at surgery and in 49% it was intra‐synovial. On presentation, the mean synovial fluid total protein level (TP) was 47.6 g/L (range 18–66); mean total nucleated cell count (TNCC) was 176 × 109 cells/L (range 12–312). Two days post‐surgery, mean total protein levels were 33 g/L (range 16–52), mean TNCC was 13 × 109 cells/L (range 1–35). At 5 days post‐surgery, the mean total protein was 23 g/L (range 12–28) and TNCC was 5 × 109 cells/L (range 1–12). All synovial fluid cultures were negative. Twenty‐eight (80%) horses were sound 5 days post‐operatively, seven (20%) were not lame in walk; they all returned to full work in an average time of 8 weeks (range 3–48 weeks). Surgery achieved accurate identification and removal of thorn material. In contrast to previous studies of synovial sepsis, these cases had a positive outcome despite high pre‐ and post‐operative synovial fluid TP and TNCC. These findings suggest that Prunus spinosus (blackthorn) synovitis has a different aetiology to synovitis originating from sepsis or other types of contamination.

A scoping review of the current evidence on treatment and outcomes following synovial sepsis

“…All six studies had small numbers of horses (range 3‐16), and no statistical analysis was performed on outcome for any of the studies. One study specifically described treatment for horses with blackthorn synovitis, 47 and one study identified outcomes in working equids 48…”

“…One study specifically described treatment for horses with blackthorn synovitis, 47 and one study identified outcomes in working equids. 48…”

Surgical treatment of synovial sepsis: Is endoscopy the best approach?

“…A range of synovial fluid analysis inclusion criteria are demonstrated in the above studies, and it would be important to use standardised diagnostic values for synovial sepsis in future studies. It is important to also be aware that the synovial fluid analysis values can vary, depending on the nature and duration of the underlying injury causing sepsis; for example, the synovial fluid TNCC can be significantly higher if the injury is caused by Prunus spinosa (blackthorn) (Ashton, 2018). It is beyond the scope of this article, however, it would be valuable in future studies to evaluate the financial implications of the different treatment methods, to further assess the effects of specific synovial fluid analysis results on the prognosis and to document the long‐term outcome of synovial sepsis affecting different synovial cavities.…”

“…The causes include traumatic injury, wounds (Milner et al., 2014), foreign body penetration (e.g. organic material such as blackthorn [Ashton, 2018]), iatrogenic causes (Lapointe et al., 1992) and haematogenous spread, the latter more commonly seen in neonates (Crosby et al., 2019; Lindegaard et al., 2021). Synovial sepsis is a serious, potentially life‐threatening and performance‐limiting condition (Richardson & Stewart, 2019).…”

Multicenter study investigating long‐term survival after synovial lavage of contaminated and septic synovial structures in horses presented to 10 UK referral hospitals

“…In the literature, only a small number of studies use multivariable analysis to investigate factors associated with short‐term and long‐term survival after treatment and the factors that have been identified differ between studies and lack consistency 10 . There are only a small number of studies that involve multiple centers 7,11 or use a prospective study design 12 …”