Treatment Comparison for Medial Femoral Condyle Subchondral Cystic Lesions and Prognosis in Yearling Thoroughbred Racehorse Prospects.

Subchondral cystic lesions (SCL) in the medial femoral condyle are a usual finding in Thoroughbred survey and auction repository radiographs. Several treatments with different outcomes have been studied over the years to improve soundness and racing prognosis. Our objective was to report the racing prognosis in Thoroughbred yearlings intended for racing that were diagnosed with SCL in the medial femoral condyle and were treated using four current and different techniques: intralesional injection of corticosteroids, SCL debridement through the joint with a drill bit, translesional cortical screw placement, and absorbable hydroxyapatite implant placement. Data from 182 Thoroughbred yearlings treated for SCL in the medial femoral condyle were collected from 2014 to 2020. Limb affected, age at surgery, sex, and radiographic measurements of the SCL were recorded. Auction price and racing performance were collected for treated horses and compared to 154 maternal siblings free of medial femoral condyle SCL. Analyses were conducted to assess if racing prognosis was affected by SCL size, to detect differences in auction price and selected flat racing outcome parameters between cases and controls, and to compare racing prognosis between the studied treatments. Mares and lesions located in the right stifle were significantly overrepresented. The auction price of treated horses was significantly lower than that of their siblings. Horses treated for SCL had significantly lower chances to start in a race than controls (59% vs. 74% respectively). Wider SCL negatively affected the chances to start at least in one race, and negatively affected the earnings made in the 2-year-olds' racing year. Horses with SCL treated using a bioabsorbable implant had a significantly higher median in starts as 3-year-olds (seven starts) than horses that had the SCL debrided with a drill bit (three starts). In conclusion, Thoroughbred yearlings treated for a medial femoral condyle SCL had lower auction prices and decreased ability to start a race compared to siblings' wider cysts had worse prognosis to start a race and might affect earnings as 2-year-olds; and horses treated with bioabsorbable composite implant placement had more starts as 3-year-olds than with other techniques.

Treatments and Prognosis for Subchondral Cystic Lesions in the Distal Extremities in Thoroughbred Prospect Racehorses.

Subchondral cystic lesions (SCLs) in equines and their treatments have been mainly studied in the medial femoral condyle of the femur. SCLs in the distal extremities affecting the fetlock or interphalangeal joints are frequent, but treatment or prognosis studies in horses are currently sparse. Our objective was to compare four treatments for SCLs in the distal extremities (intralesional injection of corticosteroids, transcortical drilling, cortical screw placement, and absorbable hydroxyapatite implant placement) and report the racing prognoses for affected thoroughbred yearlings. Data from 113 thoroughbred yearlings treated for SCLs in the distal extremities were collected from 2014 to 2020. Age at surgery, sex, bone affected, radiographic SCL measurements, SCL shape, and type of treatment were recorded. Sale data and racing performance were collected for the operated horses and for 109 maternal siblings that were free of SCLs. An analysis was conducted to assess if SCL size affected racing prognosis and to detect differences in sale value and selected racing parameters between the cases and controls. The outcomes for the different treatments, the different bones affected, and the SCL shape type were also analyzed. There was no difference in the ability to start in a race between the cases and controls (60.2% vs. 69.7%, respectively). The auction value of the treated horses was significantly lower than that of their siblings. The bone affected did not impact any of the racing variables studied, whereas the height of the SCLs negatively affected the number of wins and placed races. The type of treatment for the horses affected by SCLs did not have an impact on sale prices, ability to start a race, race starts, wins, and places, or age at the time of the first start. In conclusion, yearlings diagnosed with an SCL in the distal extremities had lower auction prices and decreased racing performances, with lower numbers of wins correlated with larger SCL heights compared to the siblings. Similar racing performance was found regardless of the treatment received.

18F-sodium fluoride positron emission tomography provides pertinent additional information to computed tomography for assessment and management of tarsal pain in horses.

OBJECTIVE: To assess the value of 18F-sodium fluoride (18F-NaF) positron emission tomography (PET) for imaging the tarsus and proximal metatarsus and compare it with CT and lameness evaluation. ANIMALS: 25 horses with lameness localized to the tarsal and proximal metatarsal regions that underwent 18F-NaF PET/CT between 2016 and 2021. METHODS: 18F-NaF PET and CT images were retrospectively independently evaluated by 3 observers. Standardized uptake values (SUV) were used to characterize 18F-NaF uptake. Correlation between PET and CT findings with subjective and objective maximum (Max-D) and minimum pelvic height lameness data was estimated. RESULTS: The inter-observer Kappa-weighted value (κ) was higher for PET (κ = 0.66) than CT (κ = 0.6). CT and PET scores were fairly correlated (R = 0.49; P < 0.05). PET SUVratio (SUV of the main lesion/SUV talus) had the highest correlation with Max-D (R = 0.71; P < .05). PET and CT scores for the plantar region were significantly higher in Quarter Horses (P < .05) and showed consistently higher correlation with objective lameness data (CT plantar grade - Max-D [R = 0.6; P < .05], PET plantar grade - Max-D [R = 0.47; P = .04]) than other regions of the distal tarsal joints. Three Warmbloods presented marked uptake at the medial cochlea of the distal tibia. CLINICAL RELEVANCE: PET had a moderate correlation with CT for assessment of tarsal lesions. The degree of PET uptake can help differentiate active versus inactive lesions. Specific location of the uptake is important in determining clinical relevance.

Computed tomography findings in horses presented with signs of head-shaking.

BACKGROUND: Trigeminal nerve-mediated head-shaking (TNMH) in horses is a diagnosis made by exclusion. Computed tomography (CT) is frequently used to identify any disease process that could cause the clinical signs of head-shaking. Although abnormalities are frequently identified, it is unknown whether treatment of these conditions improves clinical signs. OBJECTIVES: To ascertain the clinical significance of CT findings in horses presented with a complaint of head-shaking. STUDY DESIGN: Retrospective case series. METHODS: CT and patient records were reviewed and all abnormal findings and any treatments subsequently carried out was recorded. A questionnaire was sent to referring veterinarians and owners were contacted by telephone to establish whether treatment of the identified condition improved clinical signs. RESULTS: This study included 103 horses presented for head CT with the complaint of head-shaking with follow-up information obtained for 84 horses (81.6%). The diagnosis of TNMH was based on a combination of positive maxillary nerve block and/or response to treatment for TNMH. Although TNMH was the most common diagnosis with 62 horses (60.2%) affected, in 22 horses (21.4%), a primary disease process was identified and treatment of the condition eliminated signs of head-shaking. Clinically relevant primary diseases included dental fracture, primary sinusitis, temporo-mandibular joint arthritis, nuchal bursitis, musculoskeletal pathologies, basisphenoid fracture, otitis externa and a mass affecting the infra-orbital nerve. MAIN LIMITATIONS: Some clinical information was missing and follow-up information was not obtained in all cases. CONCLUSIONS: CT was perceived as a useful diagnostic tool by most veterinarians, ruling out significant abnormalities. In over 20% of the cases, a treatable primary condition was identified leading to complete resolution of clinical signs.

HISTORIAL: Las sacudidas de cabeza mediadas por el nervio Trigémino (TNMH) en caballos es un diagnostico por exclusión. La tomografía computarizada (CT) es frecuentemente utilizada para identificar cualquier proceso patológico que pudiese ser la causa de los síntomas de sacudida de cabeza. Aunque se identifican frecuentemente anomalías, no se sabe si es que el tratamiento de estas condiciones mejora los signos clínicos. OBJETIVOS: Demostrar la significancia clínica de los hallazgos por CT en caballos presentados con queja de sacudida de cabeza. DISEÑO DEL ESTUDIO: Series de casos retrospectivos. MÉTODOS: Los archivos de tomografía computarizada y de pacientes fueron revisados y todos los hallazgos anormales y los tratamientos llevados a cabo subsecuentemente fueron anotados. Un cuestionario fue mandado a los veterinarios que difirieron los casos y los dueños fueron contactados por teléfono para saber si el tratamiento de la condición identificada mejoro los síntomas. RESULTADOS: Este estudio incluyo a 103 caballos presentados para CT de cabeza con queja de sacudida de cabeza con información subsecuente obtenida en 84 caballos (81.6%). TNMH fue el diagnostico basados en un combinación de bloque positivo del nervio maxilar y/o respuesta positiva a tratamiento de TNMH. Aunque TNMH fue el diagnostico mas común con 62 caballos (60.2%) afectados, en 22 caballos (21.4%), un proceso patológico primario fue identificado y el tratamiento de la condición elimino los síntomas de sacudida de cabeza. Las enfermedades clínicas primarias relevantes incluyeron fracturas dentales, sinusitis primaria, artritis de la articulación temporo-mandibular, bursitis nucal, patologías musculo esqueléticas, fracturas basifenoideas, otitis externa y masas tumorales afectando al nervio infra-orbital. LIMITACIONES PRINCIPALES: No se pudo obtener toda la información clínica e no se obtuvo información de seguimiento en todos los casos. CONCLUSIONES: La tomografía computarizada era considerada como un herramienta diagnostica por la mayoría de los veterinarios, descartando anomalías significativas. En mas de un 20% de los casos, una condición primaria con tratamiento fue identificada y esta llevo a la resolución de los síntomas clínicos.

Visualization of anatomical structures in the fetlock region of the horse using cone beam computed tomography in comparison with conventional multidetector computed tomography.

Introduction: Cone-beam computed tomography (CBCT) is regarded as a convenient and suitable alternative to conventional computed tomography. However, in the horse, the quality of obtained data sets needs to be evaluated. Therefore, the aim of this study was to compare the visibility and accessibility of clinically relevant anatomical structures displayed in CBCT and conventional multidetector computed tomography (MDCT). Materials and methods: Twenty-nine limbs from horses euthanized for reasons unrelated to this study were used. Native and intraarticular contrast scans of the fetlock (CBCT vs. MDCT) were performed. The visibility and accessibility of selected anatomical structures were blindly scored by three independent experienced observers using a scoring system previously reported and adapted to the fetlock joint. Results: Only minor differences between CBCT and MDCT were identified concerning the diagnostic quality of images for osseous structures. Soft tissue structures were better evaluated on MDCT images. In CBCT as well as in MDCT articular cartilage could only be visualized after intraarticular injection of contrast medium. Discussion/conclusion: Cone beam computed tomography of the fetlock is a useful and reliable diagnostic tool when evaluating osseous structures and delineating articular cartilage with contrast medium. However, this modality is limited for assessing soft tissues structures.

Measurement accuracy of foot conformation parameters on low-field magnetic resonance images in horses.

Foot imbalance and malalignment of the digits are common in horses. Angle and distance measurements performed on bones, joints and hoof wall on radiographs provide essential guidance for precise corrective trimming and shoeing. This study aimed to investigate, if selected standing low-field magnetic resonance (MR) images can be used to accurately measure dorsopalmar and lateromedial foot conformation parameters in comparison to the radiographic gold standard. Images of 100 horses referred for standing low-field MR examination were selected. Foot conformation angles and distances were measured and compared between radiographs and MR images. Measurements from most imaging sources were significantly different from each other. Moderate to high correlation of foot conformation angles between radiographs and MR images in the lateromedial and dorsopalmar planes was found, with exception of the proximal interphalangeal joint angle, where there was only moderate agreement between radiographs and the 5-plane MR pilot (0.47, P < .001) and between radiographs and the 3-plane MR pilot (0.4, P < .001), respectively. Measurement of foot conformation parameters from low-field MR images should be used with caution in clinical practice and acquisition of current foot radiographs immediately before or after MR examination should be considered to facilitate precise trimming and shoeing.

Kinematic Patterns in Horses Sedated With Low Doses of Detomidine: An Accelerometric Evaluation.

Alpha-2-adrenergic drugs, such as detomidine, are commonly used to sedate lame horses during examination. However, the use of these drugs should be minimized, as they have numerous side-effects, like ataxia. Therefore, we wanted to test the effects, on the locomotor pattern, of low doses of detomidine (0.003 mg/kg). Six horses were sedated with 0.003 mg/kg of detomidine and compared with the same horses administered a saline solution. Using a triaxial accelerometer, data of kinetic, coordination and energetic locomotor parameters and the degree of sedation were collected. The effects were monitored for 60 minutes after treatment administration. No effects on coordination parameters were observed, but some kinetic and energetic parameters were significantly altered after detomidine administration compared to the saline group. These results show that administering low doses of detomidine to lame horses can be a useful sedative solution, ensuring a safe examination with lower side-effects.

Ultrasonographic visualisation of the mesenteric vasculature in horses with large colon colic.

BACKGROUND: Ultrasonographic visualisation of the mesenteric vasculature of the large colon (LC) from the right side of the abdomen in cases of displacement and volvulus has been described. However, the LC can move freely within the abdomen and its mesentery can potentially contact both sides of the abdominal wall. METHODS: Thirty-four horses presented with LC-related colic that had visible LC mesenteric vasculature visible on abdominal ultrasound were included. A control group was made including horses with confirmed small intestinal-related colic. The objective of this study was to evaluate the visibility of LC mesenteric vasculature with transabdominal ultrasonography in horses with LC-related colic and to determine its diagnostic value. RESULTS: The LC mesenteric vasculature was identified on the right side of the abdomen in 16/34 horses with right dorsal displacement of the LC (RDDLC), 180° LC volvulus (LCV), 540° LCV or LC impaction. On the left side of the abdomen, LC mesenteric vessels were identified in 17/34 horses with left dorsal displacement of the LC (LDDLC), 180° LCV or RDDLC. Vessels were visualised on both sides in one horse with a 180° LCV. Presence of LC mesenteric vasculature in the dorsal aspect on the left side of the abdomen was significantly associated with LDDLC. CONCLUSION: LC mesenteric vasculature can be visualised on transabdominal ultrasound from either side of the abdomen in horses with different forms of LC-related colic.

Magnetic resonance dacryocystography in the horse: A feasibility study.

OBJECTIVE: To provide a comprehensive anatomical description of the normal equine nasolacrimal duct using magnetic resonance imaging, and to develop a practical protocol for performing magnetic resonance dacryocystography (MRD) in horses. ANIMAL STUDIED: The heads of ten fresh horse cadavers with no history of sinonasal or ophthalmologic disorders were used for this study. PROCEDURE: An MRD technique was developed in this study, which consisted of two parts. In the first part, olive oil and gadolinium were compared as contrast medium, using five horses. Two concentrations of gadolinium were used: 0.25 mmol/mL and 0.5 mmol/mL. In the second part, the influence of different head recumbencies using olive oil as the sole contrast medium was studied in the remaining five horses. RESULTS: Injection with olive oil resulted in better distention and a complete filling of the nasolacrimal duct (ND) in all horses. Injection of 0.25 mmol/mL of gadolinium resulted in incomplete filling of the ND, whereas injection of 0.5 mmol/mL of gadolinium resulted in slightly better filling of the duct. The nondependent duct showed better distention compared to the dependent duct when scanning in lateral recumbency. No differences were observed between ducts in a dorsal recumbency. The degree of distention in dorsal recumbency was slightly less than the degree of distention observed in the nondependent ND in lateral recumbency. CONCLUSIONS: Magnetic resonance dacryocystography is a suitable technique for evaluating the nasolacrimal duct and can be performed during a normal magnetic resonance examination.

Accelerated Idioventricular Rhythm Associated With Isoflurane Administration in a Foal: A Case Report.

A 2-day-old filly was referred to the hospital with abdominal pain and constipation. The foal presented tachycardia, tachypnea, hypoxemia, hyperlactatemia, and abdominal distension. Meconium impaction was diagnosed, and the filly underwent abdominal surgery. Diazepam and butorphanol were administered for anesthesia premedication, but sedative effects were mild. Xylazine was used to enhance sedation and ketamine was subsequently administered for induction. The foal showed swallow reflex and head movement when intubation was attempted. Consequently, isoflurane on oxygen was provided via an anesthetic face mask. After intubation, the foal was connected to the anesthetic machine and monitored. The electrocardiogram revealed accelerated idioventricular rhythm, characterized by atrioventricular isorhythmic dissociation with monomorphic wide QRS complexes. Lidocaine was administered but the arrhythmia persisted during anesthesia and was spontaneously corrected once the isoflurane was discontinued at the end of the procedure. The foal recovered from anesthesia without complications and no further cardiac events were observed before the patient being discharged. Accelerated idioventricular rhythm likely resulted from administration of isoflurane to a foal presenting hypoxemia, a condition that exacerbates the risk of arrhythmia. Proper management of this abnormal rhythm is crucial as inappropriate treatments may worsen the arrhythmia.

Mediastinal Ectopic Thyroid Carcinoma and Concurrent Multinodular Pulmonary Fibrosis in a Horse.

A 30-year-old Standardbred gelding was referred for chronic pleural effusion. Thoracic ultrasound revealed marked bilateral pleural effusion and a large heterogeneous mass within the cranial mediastinum, which extended from the right 5th to the 11th intercostal space. Subsequently, on thoracic radiographs, the cranial mediastinal mass was confirmed, and a nodular interstitial pattern was identified in the lungs. Because of progressive clinical deterioration of the patient, the owners elected humane euthanasia and necropsy was performed. The mediastinal mass was consistent with an ectopic thyroid carcinoma, and the pulmonary nodules represented equine multinodular pulmonary fibrosis (EMPF). This case report describes a type of mediastinal tumor not previously described in horses. Moreover, it shows the need of including EMPF as a possible differential diagnosis for a nodular interstitial pulmonary pattern in conjunction with a mediastinal or other masses.

Magnetic resonance imaging characteristics of equine head disorders: 84 cases (2000-2013).

The equine head is an anatomically complex area, therefore advanced tomographic imaging techniques, such as computed tomography or magnetic resonance imaging (MRI), are often required for diagnosis and treatment planning. The purpose of this multicenter retrospective study was to describe MRI characteristics for a large sample of horses with head disorders. Horses imaged over a period of 13 years were recruited. Eighty-four horses met the inclusion criteria, having neurological (n = 65), sinonasal (n = 14), and soft tissue (n = 5) disorders. Magnetic resonance imaging accurately depicted the anatomy and allowed identification of the primary lesion and associated changes. There were good correlations between MRI findings and intraoperative or postmortem results. Magnetic resonance imaging showed the exact localization of the lesions, their size, and relation to surrounding structures. However, in the neurological group, there were 45 horses with no MRI abnormalities, 29 of which had a history of recurrent seizures, related to cryptogenic epilepsy. Magnetic resonance imaging was otherwise a valuable diagnostic tool, and can be used for studying a broad range of head disorders using either low-field or high-field magnets.

Imaging diagnosis--nasofrontal suture exostosis in a horse.

A 14-year-old Quarter Horse had chronic facial swelling and a more recent history of progressive bilateral epiphora. Radiographic findings were compatible with exostosis of the nasofrontal suture. Computed tomography (CT) of the head, including CT dacryorhinocystography, confirmed the diagnosis and allowed presurgical planning of resection of the exostosis, which resulted in resolution of the clinical signs.