Extensive intraocular melanoma with secondary glaucoma in a 15-month-old Thoroughbred filly.

A 15-month-old, grey, Thoroughbred filly presented for investigation of a 6-week history of corneal oedema and blepharospasm on the right eye (OD). The filly was otherwise healthy. Following ophthalmic examination, glaucoma on the OD was diagnosed. A space occupying mass within the anterior chamber was documented on transpalpebral ultrasonographic examination. This mass obliterated most of the anterior intraocular structures on the peripheral nasal side (corneal endothelium and drainage angle), leading to secondary glaucoma. After systemic and topical treatment addressing secondary glaucoma, the corneal oedema reduced. The mass was visualised as an irregularly rounded brown structure associated with the iris on the peripheral nasal side of the anterior chamber. Given the filly's signalment, location and appearance of the mass, a tentative diagnosis of intraocular melanoma was made and enucleation was performed. Histopathological evaluation of the globe revealed solid sheets of heavily pigmented melanocytic cells, disrupting the normal ciliary body architecture and extending into the iris and subretinal. The cells were pleomorphic, polyhedral to round with occasional spindle-shaped cells, and contained moderate to large amounts of granular black-brown pigment (melanin). The iridal component expanded into the anterior chamber, with cells directly opposed to Descemet's membrane, with loss of the endothelium and expanding and occluding the filtration angle in this area. The lesion infiltrated locally into the edge of the sclera, but did not extend through the sclera, though occasional perivascular clusters of melanophages were observed within the scleral stroma adjacent to the optic nerve. Diagnosis of a uveal melanocytic neoplasm was confirmed, with characteristics similar to only one reported case . This is a unique case of a rapidly growing, invasive, uveal melanoma in a young horse. Intraocular melanoma should be considered as a differential diagnoses for glaucoma in grey horses, regardless of the age and absence of melanocytic skin lesions.

Severe orbital hematoma with third eyelid swelling and prolapse following a blind maxillary nerve block in a horse.

A 20-year-old quarter horse gelding was presented for routine dental examination. Periodontal disease and luxation of tooth 108 was diagnosed and oral extraction was planned. After an unsuccessful blind maxillary nerve block, it was elected to perform the procedure under total intravenous anesthesia. Following recovery, a focal superficial corneal ulcer, severe retrobulbar swelling, mild exophthalmos, and marked swelling and prolapse of the third eyelid (nictitating membrane) were observed. Clinical signs persisted beyond 48 h despite the use of systemic anti-inflammatories and topical ocular anti-inflammatories and antibiotics. A temporary tarsorrhaphy was subsequently done at 48 h and the horse was discharged after 5 d of hospitalization and regression of clinical signs. Although it is very useful for easing dental extractions, the blind maxillary nerve block is associated with potential complications due to inadvertent vascular puncture. This case report describes a rare complication of prolapse of the third eyelid in a horse after a maxillary nerve block and successful treatment with a temporary tarsorrhaphy. Key clinical message: This case report explains how nictitating membrane swelling and prolapse can occur following a blind maxillary nerve block in the horse and describes treatment with a temporary tarsorrhaphy.

Hématome orbitaire sévère avec gonflement de la troisième paupière et prolapsus à la suite d'un bloc du nerf maxillaire à l'aveugle chez un cheval. Un hongre quarter horse de 20 ans a été présenté pour un examen dentaire de routine. Une maladie parodontale et une luxation de la dent 108 ont été diagnostiquées et une extraction orale a été planifiée. Après l'échec d'un bloc du nerf maxillaire à l'aveugle, il a été décidé d'effectuer la procédure sous anesthésie intraveineuse. Après la guérison, un ulcère cornéen superficiel focal, un gonflement rétrobulbaire sévère, une légère exophtalmie ainsi qu'un gonflement et un prolapsus marqués de la troisième paupière (membrane nictitante) ont été observés. Les signes cliniques ont persisté au-delà de 48 heures malgré l'utilisation d'anti-inflammatoires systémiques et d'anti-inflammatoires oculaires topiques et d'antibiotiques. Une tarsorraphie temporaire a ensuite été réalisée à 48 heures et le cheval est sorti après 5 jours d'hospitalisation et de régression des signes cliniques. Bien qu'il soit très utile pour faciliter les extractions dentaires, le bloc du nerf maxillaire à l'aveugle est associé à des complications potentielles dues à une ponction vasculaire involontaire. Ce rapport de cas décrit une complication rare de prolapsus de la troisième paupière chez un cheval après un bloc nerveux maxillaire et un traitement réussi par tarsorraphie temporaire.Message clinique clé:Ce rapport de cas explique comment un gonflement et un prolapsus de la membrane nictitante peuvent survenir à la suite d'un bloc du nerf maxillaire à l'aveugle chez le cheval et décrit le traitement par tarsorraphie temporaire.(Traduit par Dr Serge Messier).

Dorsal-to-palmar branch neuroanastomosis in horses undergoing palmar digital neurectomy does not reduce neuroma formation or improve outcome.

OBJECTIVE: Chronic foot pain, a common cause of forelimb lameness, can be treated by palmar digital neurectomy (PDN). Complications include neuroma formation and lameness recurrence. In humans, neuroanastomoses are performed to prevent neuroma formation. The aim of the study was to evaluate the outcome of horses undergoing dorsal-to-palmar branch neuroanastomosis following PDN. STUDY DESIGN: Retrospective case series. ANIMALS: Eighty-five horses with PDN and dorsal-to-palmar branch neuroanastomosis. METHODS: Medical records for horses undergoing this procedure at two hospitals between 2015 and 2020 were reviewed. Palmar and dorsal nerve branches of the PDN were transected and end-to-end neuroanastomosis was performed by apposition of the perineurium. Follow-up was obtained from medical records and telephone interviews. Success was defined as resolution of lameness for at least one year. RESULTS: Lameness resolved following surgery in 81/85 (95%) horses with 57/84 (68%) sound at one year. Postoperative complications occurred in 19/85 (22%) cases. The main limitations of the study were an incomplete data set, inaccurate owner recall, and variations in procedure. CONCLUSION: Compared to previous studies, this technique resulted in similar numbers of horses sound immediately after surgery, a comparable rate of postoperative neuroma formation but a higher recurrence of lameness rate at 1 year postoperatively. CLINICAL SIGNIFICANCE: End-to-end neuroanastomosis of the dorsal and palmar branches of the PDN does not reduce the rate of neuroma formation in horses. Long-term outcome was less favorable compared to previously reported PDN techniques.

A transmandibular lateral transsphenoidal navigated surgical approach to access a pituitary macroadenoma in a warmblood mare.

A 16-year-old warmblood mare was referred with a progressive history of behavioral changes and left-sided blindness. Following neuroanatomical localization to the forebrain, magnetic resonance imaging of the head revealed a well-delineated, 4.5 cm in diameter, round pituitary mass causing marked compression of the midbrain and optic chiasm. Euthanasia was recommended but declined by the owners. Veterinary specialists and a human neurosurgeon collaboratively prepared for surgical case management. A novel navigated transmandibular lateral transsphenoidal approach was developed to access the region of the sella turcica and practiced on cadaver specimens. The horse was anesthetized and placed in sternal recumbency with the head above the heart line. Using a cone beam computed tomography (CBCT)-coupled navigation system, a navigated pin traversing the vertical ramus of the mandible and the lateral pterygoid muscle was placed in a direct trajectory to the predetermined osteotomy site of the basisphenoid bone. A safe corridor to the osteotomy site was established using sequential tubular dilators bypassing the guttural pouch, internal and external carotid arteries. Despite the use of microsurgical techniques, visualization of critical structures was limited by the long and narrow working channel. Whilst partial resection of the mass was achieved, iatrogenic trauma to the normal brain parenchyma was identified by intraoperative imaging. With consent of the owner the mare was euthanized under the same general anesthesia. Post-mortem magnetic resonance imaging and gross anatomical examination confirmed partial removal of a pituitary adenoma, but also iatrogenic damage to the surrounding brain parenchyma, including the thalamus.

Implementation of a prototype dynamic laryngoplasty system in standing sedated horses provided arytenoid abduction control at seven days postoperatively.

OBJECTIVE: Evaluate a prototype dynamic laryngoplasty system (DLPS) in horses; a feasibility study. ANIMALS: 7 healthy Standardbred adult horses. METHODS: This was an in vivo experimental study. Horses had a standing surgical procedure to induce complete laryngeal hemiplegia, which was subsequently treated using the dynamic laryngoplasty system (DLPS). Activation of the DLPS was achieved using an injection port exiting through the skin (n = 2) or a subcutaneous injection port (n = 5). For each horse, endoscopic examinations of the upper respiratory tract were performed preoperatively, intraoperatively, and 7 days postoperatively. Left-to-right quotient ratios calculated during inactivated and activated states were obtained from still images of the rima glottidis acquired during day 7. In 3 horses, the device was intentionally overinflated to evaluate for device failure, and postmortem examinations were performed on day 7. For the remaining 4 horses, upper respiratory tract endoscopy was repeated at 1 month postoperatively, with no subsequent postmortem exam. RESULTS: No perioperative complications occurred, and the DLPS was effectively delivered in all horses under standing sedation. The left-to-right quotient ratio at day 7 postoperatively could be altered from a resting position of 0.76 (± 0.06) to a maximum of 0.97 (± 0.06; P < .05). The degree of arytenoid abduction could not be significantly altered after 1 month of device implantation, suspected to be due to peri-implant fibrosis. No coughing nor tracheal contamination was observed at all time points or during inflation. CLINICAL RELEVANCE: The ability to alter the degree of abduction at 7 days postoperatively with the DLPS may be beneficial in selective cases.

Equine subchondral lucencies: Knowledge from the medial femoral condyle.

Equine subchondral lucencies (SCL) have been described since the first availability of suitable radiographic equipment. The initial clinical sign can be lameness, but SCLs are often first found on surveys of juvenile horses and are primarily a radiographic concern for public auctions. When lameness is present, it varies from subtle to obvious and can be intermittent. Some SCLs heal spontaneously, and some remain blemishes, but when the SCL and lameness are persistent, further damage to the joint and limitations to an athletic career are likely. SCLs were initially described in the distal limb followed by the stifle, and the medial femoral condyle (MFC) is now considered the most common location. The aim of this review is to highlight the initial pathology and discuss the clinical and experimental information available on equine SCLs. SCL treatment has evolved from rest alone and has progressed to debridement, grafting, intralesional injection, and most recently, transcondylar screw and absorbable implant placement. Comparison of success rates between techniques is difficult due to variations in follow-up and outcome measures, and no single technique is best for all SCLs. Treatment appears to increase success by 15%-20% over rest alone, but the method chosen depends on many factors. This review emphasizes the need for further work to fully understand SCL formation and all aspects of trabecular bone healing to optimize surgical therapy and improve treatment success.

Retrospective study of perioperative antimicrobial use in horses undergoing elective laparoscopy at a single institution.

Antimicrobial stewardship has shown significant development in recent years. Perioperative prophylaxis accounts for a substantial volume of antimicrobial use and is a field in which improvements can likely be made. The objective of this study was to evaluate practices associated with perioperative antimicrobial use in equine elective laparoscopy at a single institution over a 21-year period and to determine whether antimicrobial therapy influenced the occurrence of postoperative complications. Medical records of horses that underwent elective laparoscopy at a teaching hospital from January 2000 to September 2021 were reviewed. Data obtained included signalment, surgeon, type and duration of procedure, perioperative antimicrobial use, and intraoperative and postoperative complications. Exact univariate logistic regression was used to explore the association between possible risk factors and occurrence of postoperative complications, as well as the association between year of presentation and time of antimicrobial administration. Duration of surgery was log-transformed to meet assumption of normality, followed by analysis of variance (ANOVA) to compare mean surgery time per procedure and postoperative complications. Significance was set at P < 0.05. Sixty horses met the inclusion criteria. All horses received antimicrobial prophylaxis, but none received intraoperative redosing. Only 13 horses (26%) received antimicrobials within 60 min of the first incision. Time of administration improved with each year of the study (P = 0.005). Only 17 horses (28%) received antimicrobials for less than 24 h, but median duration of antimicrobial therapy was 1.25 d (range: 0.25 to 10 d). Antimicrobial use practices at this institution differed from general recommendations for optimal perioperative prophylaxis, which suggests that intervention is required.

L'antibiogouvernance a connu un développement significatif ces dernières années. La prophylaxie peropératoire représente un volume important d'utilisation d'antimicrobiens et constitue un domaine dans lequel des améliorations peuvent probablement être apportées. L'objectif de cette étude était d'évaluer les pratiques associées à l'utilisation peropératoire d'antimicrobiens en laparoscopie élective équine dans un seul établissement sur une période de 21 ans et de déterminer si le traitement antimicrobien influençait la survenue de complications postopératoires. Les dossiers médicaux des chevaux ayant subi une laparoscopie élective dans un centre hospitalier universitaire de janvier 2000 à septembre 2021 ont été examinés. Les données obtenues comprenaient le signalement, le chirurgien, le type et la durée de la procédure, l'utilisation d'antimicrobiens peropératoires et les complications intra-opératoires et postopératoires. Une régression logistique univariée exacte a été utilisée pour explorer l'association entre les facteurs de risque possibles et la survenue de complications postopératoires, ainsi que l'association entre l'année de présentation et le moment de l'administration des antimicrobiens. La durée de la chirurgie a été transformée en log pour répondre à l'hypothèse de normalité, suivie d'une analyse de variance (ANOVA) pour comparer la durée moyenne de la chirurgie par procédure et les complications postopératoires. La signification a été fixée à P < 0,05. Soixante chevaux répondaient aux critères d'inclusion. Tous les chevaux ont reçu une prophylaxie antimicrobienne, mais aucun n'a reçu de dose supplémentaire durant la chirurgie. Seuls 13 chevaux (26 %) ont reçu des antimicrobiens dans les 60 minutes suivant la première incision. Le temps d'administration s'est amélioré avec chaque année d'étude (P = 0,005). Seulement 17 chevaux (28 %) ont reçu des antimicrobiens pendant moins de 24 heures, mais la durée médiane du traitement antimicrobien était de 1,25 jour (plage : 0,25 à 10 jours). Les pratiques d'utilisation des antimicrobiens dans cet établissement différaient des recommandations générales pour une prophylaxie peropératoire optimale, ce qui suggère qu'une intervention est nécessaire.(Traduit par Docteur Serge Messier).

Standing hand-assisted laparoscopic ovariohysterectomy to treat chronic pyometra in a mare.

OBJECTIVE: To describe a standing hand-assisted laparoscopic ovariohysterectomy in a mare. ANIMAL: A 15-year-old maiden Oldenburg mare. CLINICAL PRESENTATION, PROGRESSION, AND PROCEDURES: The mare was presented for evaluation of bucking under saddle and uncharacteristic aggressive behavior. Evaluation of a 24-hour video of the mare in a stall showed behavior consistent with caudal visceral abdominal discomfort. Reproductive evaluation revealed a pyometra secondary to complete transluminal cervical adhesions. The mare was initially managed medically with disruption of the adhesions and uterine lavage, but the adhesions reformed within 6 weeks and could not be manually disrupted. TREATMENT AND OUTCOME: To eliminate the recurrence of pyometra, the mare underwent standing hand-assisted laparoscopic ovariohysterectomy through bilateral flank incisions. The only complication was a seroma at 1 flank incision that resolved after drainage. CLINICAL RELEVANCE: Complete ovariohysterectomy in the mare is a challenging procedure and has previously been performed under general anesthesia. This is the first report of the procedure being performed completely in the standing mare without inversion of the uterus through the cervix.

One-stage surgical case management of a two-year-old Arabian horse affected by male-pseudo hermaphroditism.

A two-year-old Arabian horse presented for abnormal external genitalia and dangerous stallion-like behavior was diagnosed with disorder of sexual development (DSD), also known as intersex/hermaphroditism. Standing 1-stage surgical procedure performed under sedation, and local anesthesia to concurrently eliminate stallion-like behavior, risk of neoplastic transformation of intraabdominal gonads, and to replace ambiguous external genital with a functional, and cosmetically more acceptable anatomy. Step-1) Laparoscopic abdominal exploration and gonadectomy; Step-2) Rudimentary penis resection and perineal urethrostomy. The horse tolerated surgery well (combined surgery time 185 min) with no complications. At macroscopic examination of the gonads, they resembled hypoplastic testis-like tissues. Microscopic examination confirmed presence of seminiferous tubules, Leydig and Sertoli/granulosa cells. Cytogenetic evaluation revealed a 64,XX karyotype, SRY-negative. The stallion-like behavior subsided within days post-operatively. Long-term follow-up revealed the genitoplasty site healed without urine scalding or urethral stricture. The owner satisfaction was excellent and the horse could be used post-surgery as an athlete.

Rectal tear repair using barbed suture in the horse.

OBJECTIVE: To describe the repair utilizing integral-anchor barbed suture in equine rectal tears. ANIMALS: 3 horses aged 3 to 10 years old with grade 3 to 4 rectal tears. CLINICAL PRESENTATION: Grade 3 and 4 rectal tears were referred for surgical repair immediately after iatrogenic tearing or tearing during parturition. Integral-anchor barbed suture (Stratafix Symmetric PDS Plus, size 1, 18" CT-1) was placed using long-handled instruments or hand closure depending on the accessibility and visibility of the tear. Closure of grade 3 tears was performed using a continuous appositional pattern. A horizontal mattress pattern was performed in the grade 4 tear. No other surgical procedures were performed. RESULTS: Two grade 3 tears were successfully repaired with no complications and discharged from the hospital. One grade 4 tear was successfully repaired; however, 4 days post-surgery partial dehiscence of the suture site occurred, and the horse was euthanized. CLINICAL RELEVANCE: Grade 3 rectal tears were repaired successfully by using an integral-anchor barbed suture. No post-operative complications were reported. Blind hand suturing could be performed in cranial locations when the laceration could not be made visible. For grade 4 rectal tears, additional surgical procedures beyond barbed suture closure are needed.

Standing left recurrent laryngeal neurectomy for prospective evaluation of laryngeal hemiplegia evaluated by a high-speed treadmill test.

OBJECTIVE: To describe left recurrent laryngeal neurectomy (LRLn) performed under standing sedation and evaluate the effect of LRLn on upper respiratory tract function using a high-speed treadmill test (HST). We hypothesized that (1) unilateral LRLn could be performed in standing horses, resulting in ipsilateral arytenoid cartilage collapse (ACC); and (2) HST after LRLn would be associated with alterations in upper respiratory function consistent with dynamic ACC. ANIMALS: 6 Thoroughbred horses. METHODS: The horses were trained and underwent a baseline HST up to 14 m/s at 5% incline until fatigue. Evaluation included; airflow, pharyngeal and tracheal pressures, and dynamic upper respiratory tract endoscopy. Trans-laryngeal impedance (TLI) and left-to-right quotient angle ratio (LRQ) were calculated after testing. The following day, standing LRLn was performed in the mid-cervical region. A HST was repeated within 4 days after surgery. RESULTS: Standing LRLn was performed without complication resulting in Havemayer grade 4 ACC at rest (complete paralysis) and Rakestraw grade C or D ACC (collapse up to or beyond rima glottis midline) during exercise. Increasing treadmill speed from 11 to 14 m/s increased TLI (P < .001) and reduced LRQ (P < .001). Neurectomy resulted in an increase in TLI (P = .021) and a reduction in LRQ (P < .001). CLINICAL RELEVANCE: Standing LRLn induces laryngeal hemiplegia that can be evaluated using a HST closely after neurectomy. Standing LRLn may be useful for future prospective evaluations of surgical interventions for laryngeal hemiplegia.

Subchondral bone sequestrum formation in the proximal intra-articular and osteochondral region of the third metatarsal bone of an Appaloosa mare treated for septic arthritis.

OBJECTIVE: To raise awareness of the potential for intra-articular subchondral bone sequestrum formation secondary to a traumatic or septic process to enable more rapid identification of this uncommon but possible outcome in future cases. ANIMAL: A client-owned 12-year-old Appaloosa mare. CLINICAL PRESENTATION, PROGRESSION, AND PROCEDURES: The mare had a wound to the lateral aspect of the fourth metatarsal bone (MT4) that communicated with the distal tarsal joints. Radiographs revealed a displaced, comminuted fracture of MT4. TREATMENT AND OUTCOME: The horse underwent aggressive debridement of the wound and MT4 as well as, on 2 occasions, needle joint lavage. Systemic, regional, and IA antibiotic therapy was also performed together with a bone graft from the tuber coxae. The horse's comfort improved, and the wound appeared to be healing. Five weeks following discharge, the horse re-presented with a non-weight-bearing lameness and radiographs revealed marked osteomyelitis of the tarsometatarsal and distal intertarsal joints. Postmortem examination of the limb identified a sequestrum within the proximal articular surface of the third metatarsal bone. CLINICAL RELEVANCE: The present report highlights the importance of arthroscopic lavage to visualize the cartilage surface and the benefits of advanced imaging to detect associated changes within the bone earlier than conventional radiographs. To our knowledge, no reports exist of intra-articular subchondral bone sequestra in the tarsometatarsal joint in horses.

Arthroscopically guided lag screw fixation of subchondral bone cysts in the medial femoral condyle in Thoroughbred racehorses: description of technique and comparative results.

OBJECTIVE: To describe an arthroscopically guided technique for lag screw placement across subchondral bone cyst (SBC) in the medial femoral condyle (MFC) and to compare postoperative racing performance with corticosteroid injection and cyst debridement. STUDY DESIGN: Retrospective cohort study. ANIMALS: One hundred twenty-three horses with 134 MFC SBCs undergoing treatment at a single referral hospital in the UK between January, 2009, and December, 2020. METHODS: Sex, age, limb affected, radiographic cyst dimensions, preoperative and postoperative lameness, surgical technique (lag screw placement, cyst debridement, intralesional corticosteroid injection), and, where applicable, screw positioning were recorded retrospectively. A ratio was calculated using measurements from preoperative and postoperative radiographs. Outcome was assessed by resolution or improvement in lameness, reduction in cyst size, and starting one race after treatment. Outcome data was compared between treatment groups. RESULTS: Twenty-six of 45 (57.8%) horses that underwent transcondylar screw placement raced postoperatively, at a median of 403 days between surgery and first postoperative race. There was no difference between treatment groups with regard to racing or preoperative and postoperative lameness. Cysts treated with transcondylar screw placement had a greater reduction in cyst size and a reduced period of convalescence in comparison with those that underwent debridement; the results were similar to those treated by intralesional corticosteroid injection. CONCLUSION: Postoperative racing rates were similar for all techniques. Convalescence was reduced for lag screw placement and corticosteroid injection compared to debridement. CLINICAL SIGNIFICANCE: The arthroscopically guided technique results in radiographically consistent screw placement and cyst engagement and offers a viable alternative to other treatments.

Restoration of function following traumatic superior eyelid avulsion in a horse treated with advancement flap blepharoplasty (H-plasty) and subdermal hyaluronic acid filler.

OBJECTIVE: To describe the successful restoration of superior eyelid function in a horse following traumatic avulsion using an advancement flap blepharoplasty and subdermal hyaluronic acid filler. ANIMAL STUDIED: A 21-year-old American Paint Horse stallion who was attacked by a fellow stallion resulting in numerous traumatic injuries including avulsion of approximately 75% of the left superior eyelid. PROCEDURES: With standing sedation and locoregional anesthesia, the superior eyelid wound was debrided and an advancement flap blepharoplasty (H-plasty) and temporary tarsorrhaphy were performed. Routine healing of the surgical site occurred over the subsequent weeks, though lagophthalmos persisted. At 2 and 4 weeks post-operatively, 2.4% cross-linked hyaluronic acid was injected subdermally into the superior eyelid to attempt to improve corneal coverage. At 8 weeks post-operatively, a complete blink was restored and the cosmetic outcome was good. CONCLUSIONS: Injection of subdermal hyaluronic acid filler following eyelid injuries or blepharoplastic procedures that result in lagophthalmos can improve corneal coverage by the eyelids and allow for maintenance of a comfortable and visual eye.

Comparison of equine paranasal sinus trephination complications and outcome following standing computed tomography, radiography and sinoscopy guided approaches for the treatment of sinusitis.

OBJECTIVE: The recent availability of standing computed tomography (CT) for equine paranasal sinus disease has enhanced diagnosis and enabled more targeted surgery compared to radiography and sinoscopy. To date, there have been no studies which have critically evaluated the benefit of preoperative CT versus radiography and sinoscopy on complications and outcome in horses undergoing sinus trephination. STUDY DESIGN: Retrospective study. ANIMALS: A total of 229 equids. METHODS: The medical records of equids (229) presented for sinusitis treated via trephination that had CT, radiography and/or sinoscopy at time of surgery between 2009 and 2022 were reviewed. Outcome and complications were evaluated for six different pre- and intraoperative imaging modalities. RESULTS: The six groups did not differ in demographics or disease category, though equids with less weight (p = .0179) and shorter disease duration (p = .0075) were more likely to have radiography and sinoscopy based surgical planning. Short-term postoperative complications occurred in 30.1% and were higher in groups using preoperative CT imaging (p = .01), with hemorrhage being the most common surgical complication. Following initial trephination surgery, 57.0% (127/223) of cases resolved and there was no difference between the imaging groups. Final resolution after follow-up medical or surgical treatment increased to 94.6% (211/223) and was not different between the imaging groups or between primary or secondary sinusitis. Additional nasal fenestrations to improve sinonasal drainage, maxillary septal bulla fenestrations and trephinations to treat nasal conchal bullae were made in the CT groups. CLINICAL SIGNIFICANCE: CT provided additional diagnostic information and enabled different surgical approaches but did not improve resolution in this study population.

The influence of a tension band fixation as an adjunct for arthrodesis of the metacarpophalangeal joint in the horse.

OBJECTIVES: To determine the influence of a stainless-steel cable (SSC) tension band fixation as an adjunct to a locking compression plate (LCP) for arthrodesis of the equine metacarpophalangeal (MCP) joint. STUDY DESIGN: Experimental. An ex vivo biomechanical paired equine cadaver limb study. SAMPLE POPULATION: Five MCP joint pairs were collected from adult Thoroughbred horses, euthanized for reasons unrelated to orthopedic disease. METHODS: Each pair of MCP joints were randomly implanted with either a dorsally placed 5.5 mm LCP and a palmarly placed 2.0 mm SSC or a dorsally placed 5.5 mm LCP alone. Each construct was tested in cyclic loading followed by single cycle to failure in axial compression. Displacement at a target load of 1 kN over 3600 cycles at 1 Hz was recorded prior to single cycle to failure testing. RESULTS: In cyclic testing, displacement was not significantly different between the first and last 5% of testing cycles regardless of construct. Maximum displacement of each construct during cyclic testing was <1.1 mm. In single cycle testing, the observed yield point did not reveal any difference between LCP and LCP-SSC (p = .440). The maximum load at failure was significantly higher in LCP-SSC compared to constructs with the LCP alone (p = .046). CONCLUSION: The addition of the SSC to the LCP did not statistically affect construct displacement during cyclic loading or construct yield load during subsequent single cycle to failure. CLINICAL SIGNIFICANCE: This study provided much needed information regarding the necessity of a tension band SSC application in the arthrodesis of the MCP/MTP joint in horses.

Positron emission tomography assessment of metacarpal/metatarsal condylar fractures post surgical repair: Prospective study in 14 racehorses.

OBJECTIVES: To assess 18F-sodium fluoride (18F-NaF) positron emission tomography (PET) findings associated with metacarpal/metatarsal condylar fractures at the time of fracture repair and through healing. STUDY DESIGN: Prospective descriptive study. ANIMALS: Fourteen Thoroughbred racehorses. METHODS: 18F-NaF PET was performed within 4 days of surgical metacarpal/metatarsal condylar fracture repair, on both the injured and contralateral limb. Follow-up PET scans were offered at 3- and 5-months post fracture repair. Areas of abnormal uptake were assessed using a previously validated grading system. RESULTS: Eight fractures were located in the parasagittal groove (PSG) (six lateral and two medial) and six fractures were located abaxial to the PSG (non-PSG) through the palmar/plantar condyle (all lateral). All horses in the latter group had uptake in the lateral palmar condyle of the contralateral limb suggestive of stress remodeling. Three horses with PSG fractures had uptake in a similar location in the contralateral limb. Horses with lateral condylar fracture only presented minimal or mild uptake in the medial condyle, which is considered atypical in the front limbs for horses in full training. Four horses developed periarticular uptake in the postoperative period suggestive of degenerative joint disease, three of these horses had persistent uptake at the fracture site. These four horses did not return to racing successfully. CONCLUSION: The findings of this study provide evidence of pre-existing lesions and specific uptake patterns in racehorses suffering from metacarpal/metatarsal condylar fractures. CLINICAL SIGNIFICANCE: PET has a possible role in the prevention, diagnosis, and postoperative monitoring of metacarpal/metatarsal condylar fractures in racehorses.

Use of multiple admission variables better predicts intestinal strangulation in horses with colic than peritoneal or the ratio of peritoneal:blood l-lactate concentration.

BACKGROUND: Early identification of strangulating obstruction (SO) in horses with colic improves outcomes, yet early diagnosis of horses requiring surgery for SO often remains challenging. OBJECTIVES: To compare blood and peritoneal fluid l-lactate concentrations, peritoneal:blood l-lactate ratio, peritoneal minus blood (peritoneal-blood) l-lactate concentration and other clinical variables for predicting SO and SO in horses with small intestinal lesions (SO-SI) and then to develop a multivariable model to predict SO and SO-SI. STUDY DESIGN: Retrospective cohort. METHODS: A total of 197 equids admitted to a referral institution for colic between 2016 and 2019 that had peritoneal fluid analysis performed at admission were included. Twenty-three admission variables were evaluated individually for the prediction of a SO or SO-SI and then using multivariable logistic regression. Odds ratios (ORs) with 95% confidence intervals (CI) and area under the curve of the receiver operator characteristic (AUC ROC) were calculated. RESULTS: All variables performed better in the model than individually. The final multivariable model for predicting SO included marked abdominal pain (OR 5.31, CI 1.40-20.18), rectal temperature (OR 0.30, CI 0.14-0.64), serosanguineous peritoneal fluid (OR 35.34, CI 10.10-122.94), peritoneal-blood l-lactate (OR 1.77, CI 1.25-2.51), and peritoneal:blood l-lactate ratio (OR 0.36, CI 0.18-0.72). The AUC ROC was 0.91. The final multivariable model for predicting SO-SI included reflux volume (OR 0.69, CI 0.56-0.86), blood l-lactate concentration (OR 0.43, CI 0.22-0.87), serosanguineous peritoneal fluid (OR 4.99, CI 1.26-19.74), and peritoneal l-lactate concentration (OR 3.77, CI 1.82-7.81). MAIN LIMITATIONS: Retrospective, single-hospital study design. CONCLUSIONS: Blood and peritoneal fluid l-lactate concentrations should be interpreted in conjunction with other clinical variables. The relationship between peritoneal and blood l-lactate concentration for predicting SO or SO-SI was complex when included in a multivariable model. Models to predict SO probably vary based on lesion location.

Laparoscopic cryptorchidectomy using a resorbable self-locking loop device in dorsally recumbent horses.

OBJECTIVE: To report the use and feasibility of a self-locking resorbable loop device for cryptorchidectomy. STUDY DESIGN: Clinical prospective study. POPULATION: Twenty horses. METHODS: Horses suspected to have an abdominal testicle/s after admission work-up were enrolled. Horses were anesthetized in dorsal recumbency and a standard laparoscopic technique was performed. The looped device was inserted into the abdomen, glided around the testis/cord and tightened. Then, the spermatic cord was transected prior testis removal. Surgical procedure details and remarks, perioperative complications and total surgical time were recorded. Short- (>3 weeks) and long-term (>6 months) follow-ups were obtained by telephone questionnaire. RESULTS: Median total surgical time was 67 min (range: 43-189 min) and significantly shortened after the first four horses. The loop device was easily glided around 13/20 abdominal testes and required more time and technical skills around larger testes (≥3 years). Excellent intraoperative hemostasis was achieved in 17 horses. Three horses demonstrated mild intraoperative bleeding that required retightening, device replacement or adding a second device, respectively. Three horses developed mild postoperative hemoabdomen identified ultrasonographically and were successfully managed medically. Follow-up revealed no significant complications related to the procedure. One horse was euthanized for colic 4 months after surgery and one died of hemolytic shock 17 months postoperatively. CONCLUSION: This device represents another method to perform equine cryptorchidectomy that requires minimal training and laparoscopic expertise but demands knowledge of the device and application to prevent complications. CLINICAL SIGNIFICANCE: Laparoscopic cryptorchidectomy using this device is an alternative technique for horses <3 years.