EQUINE VETERINARY EDUCATION Equine vet. Educ. (2018) 30 (5) 227-228 doi: 10.1111/eve.12917


Highlights of recent clinically relevant papers


Recurrent laryngeal neuropathy This study by Fabrice Rossignol and colleagues in France, Germany, USA and the UK outlines a novel surgical technique for the treatment of recurrent laryngeal neuropathy (RLN) in horses.


Horses of various breeds with grade >2/4 RLN at rest


underwent a nerve transplantation procedure which involved the first or second cervical nerve being tunnelled through the left cricoarytenoideus dorsalis muscle in an attempt to reinnervate it. Successful reinnervation was confirmed within 12 months of the surgery by stimulation of the first cervical nerve under ultrasound guidance in addition to resting and exercising endoscopy being performed on most horses once back in work. Seventeen horses underwent the procedure, all without


complication arising due to the surgical technique. Twelve horses received post-operative stimulation of the first cervical nerve, 11 of which showed a positive response (defined as a clear twitching and submaximal to maximal abduction of the left arytenoid). Fourteen horses had both pre- and post- operative exercising endoscopy performed; nine of which had an improved RLN grade after surgery, four were unchanged and one had deteriorated. Abnormal respiratory noise resolved in 14/17 horses. This novel technique for the treatment of RLN has the


potential to offer a more physiological outcome than prosthetic laryngoplasty, but currently with similar success rates.


Insect bite hypersensitivity and airway hyperreactivity


In this study Simone Lanz and colleagues in Switzerland investigated whether horses affected with insect bite hypersensitivity (IBH) showed airway hyperreactivity (AH) to inhaled histamine, even in the absence of overt clinical signs of equine asthma (EA). The clinical histories of 22 healthy controls, 24 horses


suffering from IBH alone, and 23 horses suffering from IBH and EA were assessed using two standardised questionnaires, the Horse Owner Assessed Respiratory Signs Index (HOARSI), and IBH scoring. Horses were classified as EA-affected if their HOARSI was >1 and as IBH-affected if the IBH score was >0. Clinical examinations were performed to exclude confounding disorders. The arterial partial pressure of oxygen (PaO2) was measured and flowmetric plethysmography used to assess airway reactivity to increasing doses of inhaled histamine. The median histamine provocation concentration (PC)


when Mflow values increased by 35% (PC35) was significantly higher in the control group (5.94 [1.11–26.33] mg/mL) compared with the IBH group (2.95 [0.23–10.13] mg/mL) and the IBH/EA group (2.03 [0.43–10.94] mg/mL). The PC50 and PC75 showed very similar differences between groups. PaO2


was significantly lower in the IBH group (84 8 mmHg) and IBH/EA group (78 11 mmHg) compared with the control group (89 6 mmHg). These findings show that IBH is associated with AH and decreased PaO2, even in the absence of overt respiratory clinical signs.


Minocycline in tear film after oral administration


The aim of this study by Caroline Monk and colleagues at the University of Florida, USA, was firstly to determine whether minocycline was secreted in the tears of normal horses following oral administration, and secondly to determine if the concentration of minocycline directly inhibits matrix metalloproteinases (MMP) activity. Five healthy adult ponies were administered oral


minocycline at 4 mg/kg bwt every 12 h for 5 days. Tears were collected at 2, 26, 50, 56, 74, 80 and 98 h after administration. Minocycline concentrations in the tears were analysed using high performance liquid chromatography. The inhibition of recombinant human MMP-2 and MMP-9 by minocycline was investigated using fluorescence resonance energy transfer. Minocycline was present in the tears of all ponies at each


sampling point following oral administration. One of the five ponies had consistently lower levels of minocycline secretion. The concentration secreted in the tears did not directly inhibit MMP-2 or MMP-9 when tested in vitro. The inconsistencies in the tear concentration and the inhibition activity suggest topical application may be necessary to attain direct inhibition of MMP with minocycline.


Infection and risk factors following arthroscopy


In this retrospective study Julie Brunsting and colleagues in Belgium aimed to determine the incidence and risk factors of surgical site infection (SSI) and septic arthritis after elective arthroscopy in horses. Medical records of 1079 horses that had undergone


elective arthroscopy at a single equine hospital over an 8- year period were reviewed. Data including age, gender, breed, surgeon, number of joints operated, total anaesthetic time, perioperative antimicrobial administration, and the presence and size of osteochondral fragments/subchondral lesions were recorded. For each operated joint, the development of post-operative infection (SSI and/or septic arthritis) and long-term outcome (>6 months) were recorded. Association between the independent variables and the dependent outcomes was tested using multivariate logistic regression.


Arthroscopy was performed on 1741 joints in 1079 horses.


SSI without septic arthritis occurred in one fetlock joint (0.14%), one tibiotarsal joint (0.19%) and six femoropatellar joints (1.67%). Septic arthritis was diagnosed in 13 joints (0.75%), including one fetlock joint (0.14%), four tibiotarsal joints (0.74%) and eight femoropatellar joints (2.23%). The probability of post-operative SSI was higher when large lesions (>40 mm long) were treated, compared to medium (20–40 mm, P = 0.005) and small (<20 mm, P<0.001) lesions. SSI was a significant risk factor for the development of septic arthritis (P<0.001). Age did not affect the incidence of SSI; however, increasing age was associated with a lower rate of septic arthritis (P = 0.028). Septic arthritis after elective arthroscopy was more likely in


the presence of SSI and younger age. Horses with large lesions were at risk for SSI, which translated into a higher incidence of post-operative septic arthritis after femoropatellar arthroscopy.


© 2018 EVJ Ltd


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