Evaluation of the effect of laser salpingopharyngostomy on the guttural pouch environment in horses

C.C. Jukic, N.R. Cowling, N.R. Perkins, A.W. van Eps, B.J. Ahern

This study evaluated the effect of laser salpingopharyngostomy on the guttural pouch environment of healthy horses.

Six adult Standardbred horses free from endoscopic evidence of guttural pouch abnormalities were included in the study. A stab incision was made ventral to the sternocephalicus tendon and a customised trocar inserted into the into the floor of the right medial guttural pouch compartment under standing sedation.   Baseline (Day 0) temperature, humidity, oxygen (O2) and carbon dioxide (CO2) levels were recorded. A 2 cm x 2 cm salpingopharyngostomy was created into the dorsocaudal pharynx abaxially off midline into the floor of the right medial guttural pouch compartment. The guttural pouch environment was re-evaluated at 7 and 14 days post-operatively. All horses underwent URT and guttural pouch examination via endoscopy at 3 and 12 months after the completion of sampling. 

The guttural pouch environment was altered by the laser salpingopharyngostomy, with considerable variation between horses and during the sampling period. The level of CO2 post laser salpingopharyngostomy appeared to be linked directly to the horse's respiratory pattern, and the variation in CO2 was significantly different at Days 7 and 14 post laser salpingopharyngostomy compared to baseline levels. Oxygen levels were also more varied during sampling compared to baseline. There was no change in humidity or temperature during the study.

Bottom line: Laser salpingopharyngostomy into the guttural pouch may be useful in clinical cases of guttural pouch disease where alteration of the environment may be beneficial.

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Chondromalacia of the cranial medial femoral condyle; its occurrence and association with clinical outcome in a population of adult horses with stifle lameness

A. K. Croxford, R. A. Parker, J. H. Burford, D. Lloyd, J. C. Boswell, T. K. Hughes, T. J. Phillips

This retrospective cohort study aimed to document the occurrence and significance of chondromalacia of the cranial medial femoral condyle (CMFC) in adult horses with stifle lameness.

Medical records and arthroscopic surgical videos were reviewed from horses with unilateral or bilateral lameness localised to the stifle that subsequently underwent arthroscopy of the cranial medial femorotibial joint at a single equine referral hospital between 2009 and 2014.  The arthroscopy video recording for each was reviewed by three board-certified surgeons for the presence or absence of CMFC. Surgical intervention and post-operative rehabilitation varied based on the pathology and surgeon preferences. Regular exercise was not resumed for at least 6 months post-surgery. Follow-up information was obtained through telephone conversations with owners, with a satisfactory outcome being defined as a horse being in ridden work without requiring ongoing anti-inflammatory medication. 

A total of 104 horses were included in the study; 79 (76%) had CMFC, of which 54 had CMFC in combination with other pathology and 25 had CMFC alone, and 25 (24%) had other pathology. At 12 months, 62 (59.6%) horses had a satisfactory outcome. The only variable that showed any significant effect on outcome was CMFC; with horses with CMFC being 9.9 times more likely to have an unsatisfactory outcome at the 12-month follow-up period compared to those without CMFC. 

Bottom line: CMFC is associated with an increased likelihood of the horse not being in ridden work at long-term follow-up.

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External transcutaneous ultrasound technique in the equine cricoarytenoideus dorsalis muscle: Assessment of muscle size and echogenicity with resting endoscopy

Satoh, M., Higuchi, T., Inoue, S., Miyakoshi, D., Kajihara, A., Gotoh, T., Shimizu, Y.

This study aimed to evaluate the use of transcutaneous ultrasound of the left cricoarytenoideus dorsalis muscle (LCAD) and right cricoarytenoideus dorsalis muscle (RCAD) to diagnose recurrent laryngeal neuropathy (RLN).

A total of 164 Thoroughbreds underwent resting endoscopy without sedation and were graded using the 4-grade Havermeyer system. Horses with resting grades 1 and 2 with no history of abnormal respiratory noise acted as controls, whereas horses with resting grades 3 and 4 with a history of abnormal respiratory noise at exercise were deemed to be clinically ‘affected’ by RLN.

Following endoscopy, the horses were sedated and transcutaneous ultrasonography of the larynx performed. The axial plane thickness, cross-sectional area, and echogenicity of the LCAD and RCAD were measured, and the LCAD:RCAD ratios in thickness and area compared between controls and affected horses.

Thickness and area of the LCAD showed a negative correlation with resting laryngeal grade. In contrast, the thickness of the RCAD showed a positive correlation with resting laryngeal grade. Increasing RCAD thickness was found in horses with resting grades 3.II and 4, while increasing RCAD cross-sectional area was found in horses with grade 3.II. LCAD was more hyperechogenic than RCAD in resting grades 3 and 4. 

Bottom line: Assessment of the CAD using transcutaneous ultrasonography may be a useful technique in determining whether to perform nerve graft or laryngoplasty.

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Annual booster vaccination and the risk of equine influenza to Thoroughbred racehorses

Gildea, S., Lyons, P., Lyons, R., Gahan, J., Garvey, M., Cullinane, A.

This observational study investigated equine influenza (EI) outbreaks at four Thoroughbred racing yards in Ireland over a 4-week period between December 2014 and January 2015.

Repeat sampling (nasopharyngeal swabs and clotted blood samples) of all horses on affected premises was performed on a weekly basis until all horses tested negative for EI by RT-PCR. Antibodies were measured against the Irish Florida sublineage clade 2 which demonstrates 100% HA nucleotide identity to the Florida clade 2 OIE recommended vaccine strain A/eq/Richmond/1/07.

Samples were collected from 118 horses over four affected premises. Forty-five horses (38.1%) developed clinical signs, 28 of which (62.2%) tested positive by RT-PCR. Eighty horses (67.8%) were up to date with their vaccinations, of which 27 (33.8%) developed clinical signs. Eighteen of the 27 horses (66.7%) that developed clinical signs had not received a booster vaccination within the previous 6 months, and 10 (37%) were due their annual booster vaccination at the time of developing clinical signs. The first documented cases on all premises (i.e. the index cases) were vaccinated in accordance with Turf Club rules. Vaccine breakdown (morbidity when vaccinated in accordance with the Turf Club rules) was observed in 27/80 horses (33.8%) with an up to date vaccination record. 

Failure to implement appropriate biosecurity measures following the introduction of new horses and the return of horses from events contributed to disease spread, as did the movement of horses within premises. Mixing of racing and non-racing populations with inadequate vaccination histories also facilitated disease spread. 

Bottom line: Annual booster vaccination should not be relied on as the sole preventative measure against EI.

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Atrial premature depolarisations five days post electrical cardioversion are related to atrial fibrillation recurrence risk in horses

Vernemmen, I., De Clercq, D., Decloedt, A., Vera, L., Van Steenkiste, G., van Loon, G.

This retrospective case series investigated whether a high atrial premature depolarisation (APD) burden after cardioversion is associated with recurrence of atrial fibrillation (AF).

Medical records were searched for horses that successfully underwent transvenous electrical cardioversion (TVEC) for AF between 2008 and 2017.  Horses were included in the study if they met the following inclusion criteria: it was their first episode of AF, there was no AF recurrence in the first 5 days post-cardioversion, 24‐h ECG recording and echocardiographic examination 5 days post-cardioversion were available, no antiarrhythmic treatment was administered during the 24‐h ECG recording and follow‐up information was available for at least 1 year. An APD was defined as a premature P-wave, occurring at least 8% earlier, with a normal or abnormal morphology and, if conducted to the ventricles, followed by a QRS‐complex with a normal morphology. 

A total of 80 horses met the inclusion criteria, 33% of which (n = 26) experienced AF recurrence within 1 year, with a median time to recurrence of 125 days. Horses experiencing recurrence within 1 year showed a significantly higher number (median [range]) of APDs (15 [1–152]) compared with the non‐recurrence group (7 [0–304]).  In the multivariable model, ≥25 APDs/24 h, mitral regurgitation, left atrial active fractional area change and lower body weight were significantly associated with AF recurrence.

Bottom line: The APD burden 5 days post cardioversion could be a useful predictive value for AF recurrence within 1 year in horses.

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A multi‐centre cohort study investigating the outcome of synovial contamination or sepsis of the calcaneal bursae in horses treated by endoscopic lavage and debridement

Isgren, C. M., Salem, S.E., Singer, E.R., Wylie, C. E., Lipreri, G., Graham, R. J. T. Y., Bladon, B., Boswell, J. C., Fiske‐Jackson, A. R., Mair, T. S., Rubio‐Martínez, L. M.

This cohort study reports the outcome of horses with contamination/sepsis of the calcaneal bursae following endoscopic treatment in addition to identifying prognostic factors associated with survival. 

Medical records from seven referral hospitals in the UK were reviewed to identify horses that presented with synovial contamination/sepsis of the calcaneal bursae between 2002 and 2016. A total of 128 horses were included in the study; 123 of which recovered from anaesthesia. Following surgery, clinical signs improved in of 74.8% (n = 92) of cases. A total of 21 horses underwent a second surgery. Both the calcaneal bursa and the subcutaneous bursa were affected in 42.5% (n = 54) of horses, and in 48.0 % (n = 61) only the calcaneal bursa was affected.  All horses with only the subcutaneous bursa involvement survived. There was bone involvement in 23.6% (n = 30) of horses. The most common bacteria isolated were Staphylococcus spp., followed by Streptococcus spp. and Escherichia coli.

Administration of systemic antimicrobials prior to referral was associated with reduced mortality. Bone fracture/osteomyelitis, tendon involvement, duration of general anaesthesia, post‐operative synoviocentesis, and post‐operative wound dehiscence were associated with increased mortality.  At follow‐up, 87.1% horses were alive, 7.1% had been euthanised due to the calcaneal injury and 5.7% had been euthanised for unrelated reasons. From 57 horses with athletic performance follow‐up, 91.2% returned to the same or higher level of exercise.

Bottom line: Endoscopic treatment of calcaneal bursae contamination/sepsis in horses has a good survival rate with the majority of horses returning to their previous athletic use at the same or higher level. 

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Non-surgical and surgical management of metacarpo/metatarsophalangeal joint dorsal chip fracture in the Thoroughbred racehorse

Ramzan, P. H. L., Wylie, C. E.

Arthroscopy is considered the treatment of choice for dorsal osteochondral chip fractures of the metacarpo/metatarsophalangeal (MCP/MTP) joints in the racehorse. This retrospective study compared the surgical (SX) and non-surgical (non-SX) management of MCP/MTP joint dorsal chip fractures in racing Thoroughbreds.

Medical records from 2006 to 2014 were reviewed to identify Thoroughbred racehorses that were diagnosed with a MCP/MTP dorsal osteochondral chip fractures by radiography. In total, 98 horses met the inclusion criteria (70 non-SX, 28 SX), with chip fractures predominantly involving the forelimbs (n = 92, 93.9%) and considered to be clinically active in 86.7% of cases (n = 85). 

Overall, 70 horses were managed non-surgically (71.4%) and 28 underwent surgery (28.6%).   Significantly more SX horses had a reported ongoing problem associated with the affected joint than non-SX horses; however, there was no significant difference between non-SX and SX horses with respect to the number of intra-articular medications of affected joint per month of follow-up. The proportion of horses racing post-diagnosis was not significantly different between the two groups (78.6% non-SX vs 85.7% SX). The median time to first start following diagnosis for non-SX (106 days) was significantly shorter than for SX (203 days).

Bottom line: Non-surgical management may be a valid treatment option for some cases of metacarpo/metatarsophalangeal joint dorsal chip fracture.

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The safety and efficacy of neuromodulation using percutaneous electrical nerve stimulation for the management of trigeminal‐mediated headshaking in 168 horses

Roberts, V. L. H., Bailey, M., Patel, N.K.

This paper reported the results of an international, multi‐centre study investigating the use of EquiPENS™ neuromodulation for idiopathic trigeiminal-mediated headshaking.

Horses were included in analyses if they were diagnosed with trigeminal‐mediated headshaking by exclusion of all other possible causes of the clinical signs and received EquiPENS™ neuromodulation between August 2013 and November 2017. 

Each horse received an initial course of three procedures, with the first two procedures performed 3–7 days apart, and the third procedure 10–14 days after the second. A total of 530 procedures were performed on 168 horses, with 53% (n = 72) of horses going into remission following the initial course. The median duration of remission was 9.5 weeks (range 2 days–156 weeks and ongoing). Horses were significantly more likely to go into remission at the end of the first course if they went into remission after the first procedure and second procedures. Complications were reported in 8.8% (n = 47) of procedures, with worsening of clinical signs being the most frequently reported. In all but one case, complications were mild and transient, without self‐trauma. No predictors for outcome were determined.

Bottom line: Complication rates of EquiPENS™ neuromodulation are low, but there is a wide range of variation in relation to its efficacy.

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Myenteric networks of interstitial cells of Cajal are reduced in horses with inflammatory bowel disease

Fintl, C., Lindberg, R., McLean Press, C.

This retrospective study evaluated the immunohistological changes to the interstitial cells of Cajal (ICC), enteric neurons and glial cells in the small intestine of horses with inflammatory bowel disease (IBD).

Immunohistochemistry was performed on ileal samples collected at post-mortem from eight normal control horses and from 14 horses with clinical signs of IBD. The duration of illness ranged from 3 weeks to 6 months, with two horses having received corticosteroid therapy prior to euthanasia. Tissue sections were labelled with anti-CD117 (c-Kit), anti-TMEM16 (TMEM16), anti-protein gene product (PGP9.5) and anti-glial fibrillary acidic protein (GFAP). Images were then analysed to quantify the presence of ICC, neuronal and enteroglial networks.

ICC networks were significantly reduced in the myenteric plexus region in horses with IBD compared to the controls for both markers.  All IBD cases had villous atrophy and lymphoid hyperplasia of the mucosa and submucosa, but the myenteric ganglia typically appeared normal and free from inflammatory cell infiltrate.

Bottom line: Disruption to ICC networks may contribute to the clinical signs of IBD. 

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Improved diagnostic criteria for digital flexor tendon sheath pathology using contrast tenography

Kent, A.V., Chesworth, M.J., Wells, G., Gerdes, C., Bladon, B.M., Smith, R.K.W., Fiske‐Jackson, A.R.

This multicentre retrospective study aimed to evaluate contrast radiography of the digital flexor tendon sheath (DFTS) in diagnosing intrathecal tendon pathology.   

Medical records from three equine hospitals were reviewed. Horses were included in the study if they were diagnosed with lameness localised to the DFTS and had both contrast radiography and subsequent tenoscopy under general anaesthesia performed to confirm a diagnosis of a manica flexoria (MF) tear, deep digital flexor tendon (DDFT) tear or palmar/plantar annular ligament (PAL) constriction. For contrast radiography, 5-7 mL of sodium meglumine diatrizoate or Iohexol was injected with 10 mL mepivacaine hydrochloride into the DFTS.  Horses were then walked for 4–5 strides before a lateromedial radiograph of the distal limb was taken. Radiographs were reviewed by four operators blinded to case details.  Sensitivity, specificity and inter-observer variability were calculated for each pathology. 

A total of 206 horses met the inclusion criteria. Contrast tenography was a sensitive test for MF tears and specific for DDFT tears, but there was poor agreement between evaluators when diagnosing PAL constriction from contrast radiographs. Ponies and cobs were significantly more likely to be affected with MF tears, whereas Thoroughbreds, Warmbloods and draught breeds were more likely to have DDFT tears. 

Bottom line: Contrast radiography of the DFTS may offer an accurate diagnosis of certain DFTS pathologies. 

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Caudal cervical vertebral morphological variation is not associated with clinical signs in Warmblood horses

Veraa, S., de Graaf, K., Wijnberg, I.D., Back, W., Vernooij, H., Nielen, M., Belt, A.J.M.

This case-control study investigated the clinical relevance of radiographically visible morphologic variations in the caudal cervical vertebrae of Warmbloods.

Cervical radiographic examinations of all Warmblood horses (with and without clinical signs) performed between January 2011 and December 2013 were reviewed by a board certified radiologist. Morphologic variations recorded included absence of a ventral laminar part of the transverse process in combination with a ventral protuberance at another transverse process and the presence or absence of degenerative joint disease of the articular facet joint of C6 and C7. Clinical signs considered relevant included spinal ataxia, restricted flexion of the neck, cervical pain on palpation, abnormal behaviour (e.g. head shaking, bolting), cervical muscle atrophy, presumed thoracic neurological lameness and hypermetric gait. Univariable Pearson’s Chi‐square and multivariable logistic regression was used to compare the cases (horses with clinical signs) and controls (horses with no clinical signs).  

In total, 245 cases and 132 controls were included in the study. Morphologic variation at C6 and C7 was significantly less frequent in horses with clinical signs (23.7%) compared to the control group (38%).  Age, sex, breed and degenerative joint disease were not associated with the presence of clinical signs. 

Bottom line: Radiographic morphologic variations in the caudal cervical spine are more common in horses without relevant clinical signs and so should be interpreted with care.

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Restoration of arterial oxygen tension in horses recovering from general anaesthesia

Bardell, D., Mosing, M., Cripps, P.J.

This prospective study investigated changes in arterial oxygen tension (PaO₂) in horses during recovery from general anaesthesia.

In total, 102 systemically healthy horses undergoing general anaesthesia for elective surgery were included in the study. Arterial blood samples were obtained prior to administration of pre‐anaesthetic medication (baseline), at the end of anaesthesia, when placed in recovery, at 10 minute intervals whilst in lateral recumbency, immediately upon achieving sternal recumbency, at 10 minute intervals until standing and 1 hour after standing (STAND+1).

Pre‐anaesthetic medication consisted of acepromazine, an alpha-2 adrenoreceptor agonist and a µ‐receptor agonist opioid. Induction was achieved with thiopental or ketamine plus a benzodiazepine, and anaesthesia was maintained with isoflurane or sevoflurane. Forty horses received controlled mandatory ventilation (CMV) throughout anaesthesia, 47 breathed spontaneously (SV) and 15 breathed spontaneously before CMV was commenced (S‐CMV). 

Overall, PaO₂ alveolar‐to‐arterial oxygen tension difference (P(A‐a)O₂) and arterial carbon dioxide tension (PaCO₂) remained significantly lower than baseline at the STAND+1 time point. The only group in which these values had returned to baseline values at STAND+1 was S‐CMV.  CMV resulted in higher PaO₂ at the end of anaesthesia and during early recovery than SV. Highest PaO₂ values associated with CMV were also associated with early recovery apnoea. Oxygen supplementation in recovery resulted in higher mean PaO₂ than horses receiving no additional oxygen. High PaO₂ values did not appear to adversely affect outcome.

Bottom line: Controlled mandatory ventilation during general anaesthesia may result in better pulmonary function in horses.

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A 10‐year study of arthroscopic surgery in racing Thoroughbreds and Quarterhorses with osteochondral fragmentation of the carpus

Graham, R. J. T. Y., Rosanowski, S. M., McIlwraith, C. W.

This retrospective study aimed to identify associations between the severity and location of osteochondral fragments in the carpus and to describe the racing performance of horses pre‐ and post‐ arthroscopic removal in Thoroughbreds and Quarter Horses. 

The medical and racing records of racehorses that underwent carpal arthroscopy between 2006 to 2016 due to clinical signs and radiographic findings consistent with carpal chip fragmentation were retrospectively reviewed. Signalment, location of fragmentation and grade of defect after arthroscopic removal and debridement were described and logistic regression used to identify factors associated with an unsuccessful return to racing.

In total, 828 horses (416 Quarter Horses and 412 Thoroughbreds) underwent 880 carpal arthroscopies for removal of fragments. A total of 65% and 27% of lesions were bilateral in Quarter Horses and Thoroughbreds, respectively, with the most commonly affected bone in both breeds being the dorsodistal radial carpal bone.  Overall, 82% of horses raced post‐surgery, with 69.5% racing at the same or a higher level. Factors associated with horses not returning to racing post‐surgery were increasing horse age, being female, and a lesion grade of 4/4, while racing pre‐surgery appeared protective.

There were significant differences between the location and severity of lesions in Quarter Horses compared to Thoroughbreds. The majority of horses returned to racing following surgery, with lesion severity affecting performance.

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A histological and ultrastructural study of equine peripheral caries

Borkent, D., Smith, S., Dixon, P.M.

This study examined cheek teeth affected by periperhal caries (PC) histologically and ultrastructurally in order to try and establish the route of cariogenic bacterial invasion and to describe the resulting pathological changes.

A total of 16 cheek teeth from horses that had died of non‐dental related disease with varying grades of PC were examined alongside four control teeth (no PC). The teeth were macroscopically assessed. Of those with PC, 11 had partial cemental caries (grade 1.1 PC), three had total cemental caries (grade 1.2 PC), three had caries of cementum and the underlying enamel (grade 2 PC) and two had caries of cementum, enamel and dentine (grade 3 PC). Samples for histological and electron microscopy examination were prepared.

Bacteria from plaque entered the peripheral cementum perpendicular to the sides of the teeth alongside Sharpey's fibres or vascular channels or more horizontally alongside exposed intrinsic fibres and cemental growth lines. Intra‐cemental bacterial spread caused varying patterns of cemental caries as identified histologically: horizontal flake‐like lesions (Type A), vertical flake-like lesions (Type B), flask‐like lesions (Type C) and small ellipsoid, lytic lesions (Type D). Regardless of mechanism, cariogenic bacteria commonly tracked along the intrinsic fibres in lines of arrested growth (LAGs), causing further demineralisation of adjacent cementum and disintegration of these fibres. Cemental caries progressed to affect enamel, dentine and pulp.  

Bottom line: Equine peripheral caries cause different patterns of cemental lesions which may be dependent on the route of bacterial invasion. Gross examination can underestimate the true extent of peripheral caries.

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Race performance following epiglottic entrapment surgery in Thoroughbred yearlings

Curtiss, A.L., Aceto, H., Embertson, R.M.

This retrospective study aimed to evaluate the racing performance of horses treated surgically for epiglottic entrapment as yearlings compared to their maternal half‐siblings.

The medical and race records of 66 Thoroughbred (TB) yearlings treated surgically for epiglottic entrapment by axial division with a hook bistoury or diode laser were analysed. For each treated horse, two maternal half‐siblings closest in age were selected as the untreated control cohort. Racing performance was assessed by comparing quarterly starts and earnings, career longevity, rates of racing and earnings. Associations between clinical variables and not racing post‐surgery were evaluated using logistic regression.

In total, 66 treated horses were included in the study, with there being significantly more females than males in the treated group. The proportions of horses that raced were similar in the treated and maternal cohorts, with the treated horses performing to a similar level to their untreated controls. In treated horses, epiglottic entrapment with abnormal right arytenoid movement was associated with never racing.

Bottom line: Thoroughbred racehorses treated in their yearling year for epiglottic entrapment had no differences in performance variables compared to their untreated cohort. 

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Serum amyloid A and plasma fibrinogen concentrations in horses following emergency exploratory celiotomy

De Cozar, M., Sherlock, C., Knowles, E., Mair, T.

This study aimed to compare serum amyloid A ([SAA]) and plasma fibrinogen ([fibrinogen]) concentrations in the immediate post-operative period in horses undergoing exploratory celiotomy for colic unresponsive to medical management.

All horses received preoperative procaine benzylpenicillin (20 mg/kg bwt), gentamicin sulphate (6.6 mg/kg bwt) and flunixin meglumine (1.1 mg/kg bwt). Post-operatively, all horses received balanced polyionic intravenous fluids, with some also receiving a 2% lidocaine continuous rate infusion. Gentamicin sulphate and procaine benzylpenicillin were continued for 24–120 h, and flunixin meglumine (1.1 mg/kg bwt intravenously twice daily) was continued for a further for 3–5 days. [SAA] and [fibrinogen] were measured prior to surgery at admission and daily for 5 days following surgery.

In total, 300 horses were included in the study, 52.0% of which developed post-operative complications and 83.7% survived to discharge. Median [SAA] on days 1, 2, 3, 4 and 5 and median [fibrinogen] on days 3, 4 and 5 were significantly different between horses that did and did not develop post-operative complications, whilst median [SAA] on days 1, 4 and 5 were significantly different between horses that did and did not survive to discharge. Post-operative complications were associated with strangulating lesions and higher [fibrinogen] at admission. Survival to discharge was associated with lower [SAA] at 5 days post-operatively.

Bottom line: Measuring [SAA] daily and [fibrinogen] at admission may help predict the development of post-operative complications.

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Continuous fluid infusion per rectum compared with intravenous and nasogastric fluid administration in horses

Khan, A., Hallowell, G.D., Underwood, C., van Eps, A.W.

This randomised controlled crossover study compared the use of rectally administered fluids to nasogastric and intravenous administration.

Six healthy horses each received each of three different fluid treatment protocols (intravenous Hartmann's, nasogastric polyionic solution and rectally administered tap water) at 5mL/kg/h and also underwent a control protocol (no treatment) while feed and water was withheld for 6 hours.  A minimum 2‐week washout period was observed between each treatment.

Prior to administering rectal fluids the rectum was manually evacuated and a 24 Fr flush enema tube inserted approximately 50 cm into the rectum and secured to the tail. Fluid was delivered continuously by gravity flow.  Packed cell volume (PCV), total solids (TS), albumin, electrolytes, lactate, urine specific gravity, vital parameters, gastrointestinal borborygmi and central venous pressure were measured every 2 hours.

Rectal administration of fluid was well tolerated in all horses. PCV decreased over time with all fluid treatments but not with the control, and TS decreased with intravenous and rectally administered fluid.  There was an increase in gastrointestinal borborygmi with rectally administered fluid. 

Bottom line: Rectal fluid administration may offer an effective, inexpensive alternative or adjunct to intravenous fluid therapy, particularly when administration via nasogastric tube is not possible or contraindicated.

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Intralesional application of medical grade honey improves healing of surgically treated lacerations in horses

Mandel, H. H., Sutton, G. A., Abu, E., Kelmer, G.

This prospective, randomised clinical study aimed to evaluate the effect of intralesional medical grade honey (MGH) on wound infection and dehiscence following closure.

A total of 127 horses were included in the study and randomly allocated into the treatment (MGH; 69 horses) or control (58 horses) group.  Neonatal foals, horses with major systemic illness, penetrating wounds requiring hospitalisation and eyelid lacerations were excluded from the study. 

All wounds were first cleaned thoroughly with diluted chlorhexidine or diluted povidone iodine followed by a balanced sterile electrolyte solution. The MGH group had sterile MGH (L‐Mesitran gel) applied directly onto the subcutaneous tissue prior to skin closure or after partial wound closure. Data relating to wound healing was subsequently collected from the 11 participating practitioners through questionnaires and telephone conversations.

No adverse effects of the MGH were recorded in any of the horses participating in the study. MGH‐treated horses were significantly more likely to heal completely, to have no signs of infection and for the veterinarians to report some degree of satisfaction compared to control cases.

Bottom line: Intralesional application of MGH to lacerations prior to wound closure may help prevent wound infection and therefore dehiscence. 

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Equine ulcerative keratitis with furrow: a review of the outcomes of 72 cases from 1987 to 2015

Berkowski, Jr. W. M., Craft, W. F., Whitley, R. D., Brooks, D.E., Plummer, C. E.

This retrospective case series from the USA aimed to describe the features and outcomes of horses with ulcerative keratitis with an associated peripheral furrow (circumferential thinning of the corneal stroma ≥20% deeper than the central lesion and surrounding cornea).  

A total of 72 horses with furrow-forming ulcerative keratitis seen at the University of Florida between 1987 and 2015 were included in the study. A definitive aetiologic diagnosis was available for 37 eyes; with 27% (n = 10) diagnosed with fungal keratitis, 38% (n = 14) with a mixed fungal and bacterial keratitis and 35% (n = 13) with bacterial keratitis. 

Treatment varied between patients. In total, 36% of eyes (n = 26) were treated with medical therapy alone and the remaining 64% (n = 46) were treated with a combination of medical and surgical therapy. Surgical interventions included keratectomy (superficial keratectomy, anterior lamellar keratectomy, or penetrating keratoplasty) with or without an accompanying graft or conjunctival flap. Grafting materials included frozen equine donor cornea, equine amniotic membrane, and/or processed porcine small intestine. Of those that received medical therapy alone, 20 (77%) healed with a positive visual outcome and 6 eyes were non-visual (23%). Of the 46 eyes which received surgical intervention, 40 (87%) healed with a positive visual outcome and six eyes were non-visual (13%). In total, 83% (n=60) of eyes healed with a positive visual outcome following surgical and/or medical treatment. The remaining 17% (n = 12) were considered treatment failures, with six requiring enucleation and six becoming phthisical.

Bottom line: Cases of ulcerative keratitis with furrow may have a more favourable prognosis than previously thought. The specific aetiologic diagnosis was not a significant predictor of visual outcome.  Surgical treatment was not associated with an increased likelihood of a positive visual outcome.

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Misoprostol is superior to combined omeprazole‐sucralfate for the treatment of equine gastric glandular disease

Varley, G., Bowen, I. M., Habershon-Butcher, J. L., Nicholls, V., Hallowell, G. D.

This prospective UK study compared the efficacy of misoprostol and combined omeprazole‐sucralfate for the treatment of equine gastric glandular disease

Horses were enrolled onto the study if they presented with clinical signs consistent with equine gastric disease and were subsequently found to have grade >1/4 glandular disease identified by gastroscopy. Horses were assigned to one of the two treatment groups (5 μg/kg misoprostol orally twice daily or 4 mg/kg enteric coated omeprazole plus 12 mg/kg sucralfate orally twice daily) based on the hospital at which they were initially examined. Gastroscopy was repeated 28–35 days after the initial examination and images were reviewed by clinicians blinded to the treatment received.  Owners/keepers were not blinded to the treatments and were asked to complete a questionnaire prior to both gastroscopy examinations. Lesion healing was defined as improvement to a grade 0, and horses were considered to have improved if the score decreased by at least one grade. 

A total of 63 horses met the inclusion criteria, with poor performance being the most common presenting sign. All horses had lesions involving the pylorus and/or pyloric antrum, and there was an overall reduction in lesion score in both treatment groups. Of those treated with misoprostol, 72% of lesions healed, compared to 20% of the omeprazole‐sucralfate group. In addition, 98% of horses in the misoprostol group improved, compared to 65% in the omeprazole‐sucralfate group. Overall healing and improvement of lesions were associated with resolution of clinical signs.

Bottom line: Misoprostol was superior to combined omeprazole‐sucralfate treatment both for improvement and healing of gastric glandular lesions.

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Salivary alpha‐amylase activity and concentration in horses with acute abdominal disease: Association with outcome

Contreras‐Aguilar, M. D., Martínez‐Subiela, S., Cerón, J. J., Martín‐Cuervo, M., Tecles, F., Escribano, D.

This prospective cohort study compared salivary alpha‐amylase (sAA) activity and concentration in healthy horses to those with acute abdominal disease.

Horses referred to the Veterinary Teaching Hospital of the University of Extremadura between May and December 2017 for evaluation of colic and subsequently diagnosed with acute gastrointestinal disease were included in the study. A healthy population of horses with normal haematological and biochemical parameters were selected from those admitted for castration or routine health check. Saliva samples were collected from both groups within 30 minutes of arrival at the hospital and prior to examination and treatment.

A total of 25 healthy horses and 33 with acute abdominal disease were included in the study. sAA activity and concentration were significantly different between the two groups. Among the diseased group, sAA activity was higher in non‐survivors compared to survivors. Activity and concentration correlated moderately with heart rate and plasma lactate and weakly with salivary cortisol and systemic inflammatory response syndrome (SIRS) score. The sAA activity was significantly associated with increased risk of nonsurvival.

Bottom line: sAA activity could be a potential biomarker of prognosis in horses with acute abdominal disease.

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Prospective, randomised clinical trial of four different presurgical hand antiseptic techniques in equine surgery

Biermann, N. M., McClure, J. T., Sanchez, J., Saab, M., Doyle, A.J.

Currently, the World Health Organization recommends the use of alcohol‐based hand rubs (ABR) for surgical hand preparation in human surgery. When disinfecting soaps are used, a rubbing technique causes less skin irritation than brush scrubbing. Based on a recent survey, most equine surgeons still use disinfecting soap. This prospective clinical trial compared the efficacy of four surgical hand preparation techniques (three rubs and one scrub) for reduction of aerobic bacterial counts from pre‐ to post‐preparation (immediate efficacy) and at the end of surgery (sustained efficacy). 

The four techniques used were a hand scrub with 4% chlorhexidine gluconate soap (CHx scrub), a hand rub with 4% chlorhexidine gluconate soap (CHx rub), a hand rub with 61% ethanol solution with 1% chlorhexidine gluconate (CHx/ET), and a hand rub with a mixture of 30% 1‐propanol and 45% 2‐propanol solution (IPO). 

Clinicians participating in equine surgical procedures were enrolled during an 18‐month study period and were not blinded to hand preparation technique. Techniques were randomly assigned and a wash out period of approximately 3 days given between them. Samples were collected by the glove juice technique after one‐minute of a neutral soap hand wash (pre‐preparation), following completion of the randomly assigned hand preparation technique (post-preparation), and finally at the end of surgery (post-surgery). Aerobic bacterial log10 colony forming units (CFU) counts were performed.

A total of 228 hands from seven clinicians were sampled in 109 surgical procedures. Immediate mean bacterial log₁₀ CFU reduction was 2.4 for CHx‐scrub, 2.8 for CHx‐rub, 3.1 for CHx/ET rub and 2.1 for IPO rub. CHx/ET rub resulted in significantly lower bacterial counts than CHx‐scrub and IPO rub, while CHx‐rub resulted in significantly lower counts than IPO rub. At the end of surgery bacterial counts were the lowest for CHx‐rub, significantly lower than CHx/ET rub (P<0.001) and IPO rub (P<0.001). There was no difference between CHx‐rub and ‐scrub techniques. 

Bottom line: ABR did not decrease bacterial log₁₀ CFU counts more effectively than CHx products. When using CHx soaps in the equine setting, hand‐rub is as effective as a hand‐scrub technique.

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Diffusion of enrofloxacin to pregnancy fluids and effects on fetal cartilage after intravenous administration to late pregnant mares

Ellerbrock, R. E., Canisso, I. F., Roady, P. J., Rothrock, L. T., Zhong, L., Wilkins, P., Dirikolu, L., Lima, F. S., Honoroto, J.

This study investigated the concentration of enrofloxacin and ciprofloxacin in pregnancy fluids when administered during late‐term pregnancy, in addition to assessing the effect on fetal articular cartilage. 

Sixteen healthy pregnant mares at 260 days gestation were randomly allocated into one of three groups: control (no treatment; n = 3), enrofloxacin 5 mg/kg bwt i.v. (recommended therapeutic dose; n = 7) and enrofloxacin 10 mg/kg bwt i.v. (supratherapeutic dose; n = 6). Enrofloxacin was administered s.i.d. for 11 days. Amniotic and allantoic fluid were sampled on days 1, 5 and 11, and blood samples obtained daily.  

On day 11 abortion was induced by manual cervical dilation and the fetuses euthanased following delivery. Fetal articular cartilage was examined macroscopically and histologically for lesions. Concentrations of enrofloxacin and ciprofloxacin in samples were measured by liquid chromatography-tandem mass spectrometry.

Enrofloxacin and ciprofloxacin reached fetal circulation and accumulated in the pregnancy fluids, reaching the minimum inhibitory concentrations for common pathogens in all fluids. No differences were seen in fetal serum biochemistry values between the control and treatment groups. No lesions were noted on gross inspection of any fetal articular surface and no major abnormal findings were observed on histological evaluation.  

Bottom line: Enrofloxacin and ciprofloxacin are detectable in the fetus and fetal fluids after administration to late‐term mares but did not result in detectable effects on foal cartilage.

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Atypical myopathy‐associated hypoglycin A toxin remains in sycamore seedlings despite mowing, herbicidal spraying or storage in hay and silage

González‐Medina, S., Montesso, F., Chang, Y.‐M., Hyde, C., Piercy, R.J.

This study investigated various pasture management strategies employed to avoid hypoglycin A (HGA) intoxication in horses.

Sycamore seedlings from nine locations were either mowed (n = 6) or sprayed with a herbicide (dimethylamine‐based n = 2; picolinic acid‐based n = 1).  Seedlings were analysed for HGA concentration before intervention and at 48 h, 1 and 2 weeks after. Cut grass in the vicinity of mowed seedlings was also analysed prior to and 1 week after intervention.  Seeds and seedlings maintained for 6 months in processed grass forage (hay and silage) were also analysed. 

There was no significant decline in HGA content in mowed or sprayed seedlings; with mowing inducing a temporary significant rise in HGA in the seedlings. HGA was still present in sycamore material after 6–8 months storage within either hay or silage.

Bottom line: Neither mowing nor herbicidal spraying reduces HGA concentration in sycamore seedlings up to 2 weeks after intervention. Pastures contaminated with sycamore material should not be used to produce processed hay or silage.

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