EQUINE VETERINARY EDUCATION / AE / SEPTEMBER 2017
491
subsequent to bacterial peritonitis has been reported in an Arab gelding (Archer et al. 2004). A case of septic infection of the DDFT following bacterial peritonitis was observed some years ago in our Veterinary Teaching Hospital. (M. Pepe, personal communication). The 5 cases of primary tendon infection described by Kidd et al. (2002) were characterised by acute onset, severe lameness, pain on palpation of the limb and very rapid progression of ultrasonographic lesions. It was reported that 4 of the 5 affected horses had competed on the day prior to the onset of lameness, suggesting that an aseptic traumatic tendon core lesion may subsequently have become infected. O’Sullivan et al. (2015) described a case of septic
infraspinatus and intertubercolar bursitis suspected to be secondary to haematogenous bacterial spread from an ipsilateral subsolar abscess in a Standardbred racehorse. In the case reported here, the reason for presentation
was intermittent fever and chronic weight loss, and the patient had been treated for a respiratory disease by the referring veterinary surgeon. In this case report, it is interesting to note that
S. zooepidemicus was isolated from culture of the transtracheal wash, from the lesion of the DDFT and from the synovial fluid of the DFTS, and all isolates showed the same results on sensitivity testing. This aerobic organism is a mucosal commensal that produces disease opportunistically in situations of virus infection, heat stress or tissue injury (Sellon 2007). It is the pyogen isolated most frequently from equine joints, lymph nodes, nasal cavities and lungs (Timoney 2004) but its isolation from a tendon has never been reported. In the previous reported cases (Kidd et al. 2002), a coagulase- positive Staphylococcus was isolated in 3 of 5 cases, a Proteus sp. in one, and no bacteria were isolated in one case. From the sample obtained from the intertubercular bursa (O’Sullivan et al. 2015) a Staphylococcus intermedius was cultured and in the case described by Archer et al. (2004) no bacteria were cultured. In mature horses, bacteria may colonise a tendon sheath or joint before the immune system can kill the organisms (Honnas et al. 1991; Schneider et al. 1992); however, haematogenous spread as a cause of septic arthritis/tenosynovitis is rare (Schneider et al. 1992). In our case, the exact aetiopathogenesis of the tendon
lesion is unknown, but on the basis of the anamnesis, and the clinical and laboratory findings, we suspect haematogenous spread of bacteria from the pulmonary area. The ultrasonographic findings from the thorax may be consistent with the later stages of pleuropneumonia. It could be hypothesised that septic thrombi, associated with pleuropneumonia, metastasised and were entrapped in the microcirculation of the tendon or of the DFTS, producing infection; however, it is difficult to demonstrate this theory. It has been reported that, in septic tenosynovitis, the aetiology of the infection is significantly associated with the type of bacteria identified by culture (Schneider et al. 1992). Horses that develop an infection secondary to a penetrating wound frequently provide cultures of more than one organism (Schneider et al.1992; Meijer et al. 2000; Taylor et al. 2010). In this case, only one bacterial species was isolated from the DDFT and DFTS, and this supports our hypothesis of haematogenous spread of the infection, hypothesis supported by the 4-month history of respiratory disease vs. the 2-week lameness history.
Unlike the previously described cases (Kidd et al. 2002), in
the present report the concurrent presence of septic tenosynovitis of the DFTS was noted: is not possible to exclude that the tendon infection was secondary to septic DFTS tenosynovitis but, in the authors’ opinion, the DFTS infection was considered to be secondary to the septic tendonitis. Infection of the superficial digital flexor tendon and DDFT secondary to chronic DFTS sepsis and infection of the DDFT secondary to tarsal sheath sepsis have been recognised (Kidd et al. 2002, 2004), but they did not result in central anechoic core lesions as described in this case. If the infection had been the result of extension from adjacent tissues, we would expect the tendon lesion to begin on the periphery, as described in cases of tendon rupture secondary to tendon sheath sepsis (Kidd et al. 2004), and not to develop as a centrally located lesion. Septic tenosynovitis represents a serious, performance-
limiting and often life-threatening condition in horses. Treatment of septic tenosynovitis is frequently described in literature. Such cases require early and aggressive management consisting of antimicrobial therapy, drainage/ debridement and supportive care/pain management (Caron 2011). Septic tendonitis is refractory to treatment and only few reported cases were treated successfully by a combination of drainage and antimicrobial therapy (Schneider et al. 1992; Kidd et al. 2002). In the case presented here, surgical drainage of the DFTS was discussed with the owner, but because of the severity of the lesion, skin infection and the guarded prognosis for a return to full athletic function, the owner declined surgery. However, the horse was subjected to aggressive systemic and local antimicrobial therapy with a positive clinical response shown by improvement of the lameness a few days after treatment. In this case, a combination of systemic and local antimicrobial therapy, performed by ultrasound-guided injection, and supported by an adequate pain management, allowed the horse to return to full athletic activity. The excellent response to the medical treatment despite the severity of the lesion surprised the authors and suggests that an aggressive medical approach can produce good results in cases of septic tendon and sheath lesions. In the authors’ opinion, collection of consecutive samples from the tendon and the sheath during the time of the medical treatment represents a useful aid to monitoring the evolution of the infection. More cases are required to investigate the exact aetiology of tendon infection in the absence of evidence of a penetrating wound, and to establish the optimal therapy to guarantee a good long-term prognosis, not only for survival but also for athletic function.
Authors’ declaration of interests No conflicts of interest have been declared.
Ethical animal research
Informed consent was obtained from the owners of the horse in the study.
Source of funding None.
© 2015 EVJ Ltd
Page 1 |
Page 2 |
Page 3 |
Page 4 |
Page 5 |
Page 6 |
Page 7 |
Page 8 |
Page 9 |
Page 10 |
Page 11 |
Page 12 |
Page 13 |
Page 14 |
Page 15 |
Page 16 |
Page 17 |
Page 18 |
Page 19 |
Page 20 |
Page 21 |
Page 22 |
Page 23 |
Page 24 |
Page 25 |
Page 26 |
Page 27 |
Page 28 |
Page 29 |
Page 30 |
Page 31 |
Page 32 |
Page 33 |
Page 34 |
Page 35 |
Page 36 |
Page 37 |
Page 38 |
Page 39 |
Page 40 |
Page 41 |
Page 42 |
Page 43 |
Page 44 |
Page 45 |
Page 46 |
Page 47 |
Page 48 |
Page 49 |
Page 50 |
Page 51 |
Page 52 |
Page 53 |
Page 54 |
Page 55 |
Page 56 |
Page 57 |
Page 58 |
Page 59 |
Page 60 |
Page 61 |
Page 62 |
Page 63 |
Page 64 |
Page 65 |
Page 66 |
Page 67 |
Page 68 |
Page 69 |
Page 70 |
Page 71 |
Page 72 |
Page 73 |
Page 74 |
Page 75 |
Page 76 |
Page 77 |
Page 78 |
Page 79 |
Page 80 |
Page 81 |
Page 82 |
Page 83 |
Page 84 |
Page 85 |
Page 86 |
Page 87 |
Page 88
