Subconjunctival autologous muscle-derived mesenchymal stem cell therapy: A novel, minimally invasive approach for treating equine immune-mediated keratitis.

OBJECTIVE: To establish the safety of subconjunctival injections of autologous muscle-derived mesenchymal stem cells (mdMSCs) in healthy horses and to evaluate their effect in four horses (six eyes) with severe chronic equine immune-mediated keratitis (IMMK) that was unresponsive to medical treatments. METHODS: MdMSCs were cultured from minimally invasive muscle biopsies. In the safety group, four healthy horses received two subconjunctival injections of 2.5 and 5 million cells, respectively, at 1-month interval, to the same eye. Ocular side effects were monitored for 1 month following each injection. In the treatment group, six eyes received four to seven subconjunctival mdMSCs injections (2.5 or 5 million cells per injection) every 4 weeks, approximatively. Medical treatment was discontinued 1 week before and throughout the entire treatment period. A scoring system was used to assess the evolution of the ocular lesions. RESULTS: In the safety group, all horses exhibited mild to moderate chemosis and conjunctival hyperemia at the injection site, lasting 24-48 h. In the treatment group, all eyes initially responded positively to therapy, with a reduction in lesion scores observed after the first injection. Four eyes achieved control of the lesions with repeated injections during the 9.2 months of follow-up. CONCLUSION: The first subconjunctival injection of mdMSCs resulted in improvement of the ocular lesions. Repeated injections were found to be safe, minimally invasive and showed promise in managing refractory cases of equine IMMK. Further studies are warranted to demonstrate the long-term benefits of these injections and to optimize the therapeutic protocol.

Equine ulcerative keratitis in Belgium: Associated bacterial isolates and in vitro antimicrobial resistance in 200 eyes.

PURPOSE: To describe bacterial isolates and associated antibiotic resistance from horses with ulcerative keratitis in Belgium. METHODS: Medical records from horses with ulcerative keratitis presented to the ophthalmology service of the Veterinary teaching hospital of Liege, Belgium, between 2014 and 2021 were evaluated. Bacterial isolates were identified and VITEK® 2 (Biomérieux) provided antimicrobial susceptibility testing and resistance detection. RESULTS: Two hundred eyes of 196 horses were sampled. Ninety-seven eyes had a positive bacterial culture (48.5%) and 139 bacterial isolates were identified. Staphylococcus (63/139: 45.3%) and Streptococcus (33/139: 23.7%) were the most frequent genus isolated. Staphylococcus aureus (21/139: 15.1%) was the most frequent species isolated of which half were methicillin-resistant (MRS). Streptococcus equi subsp. zooepidemicus (19/139: 13.7%) was the second most identified bacterial isolate. Only two Pseudomonas species were isolated (2/139: 1.4%). The overall resistance of all bacterial isolates against chloramphenicol (12.4%) and fluoroquinolones (14.3%) was low. Resistance against tobramycin, polymyxin B, gentamicin, fusidic acid, tetracycline, and neomycin ranged from 40.8% to 58.6%. When separating the MRS from the other staphylococci, a significant difference was noted in percentage of resistance to gentamicin (p = .00026) and tetracycline (p = .00015). MRS were highly resistant to gentamicin (75%) and tetracycline (100%), whereas the remaining staphylococci were significantly less resistant to gentamicin (17%) and tetracycline (40.4%). CONCLUSION: Although Pseudomonas species has been rarely cultured, our results are roughly consistent with previous studies. Multiple drug resistance was high and resistance to first-choice antibiotics in ulcerative keratitis was noted. These results warrant continued monitoring of susceptibility profile.

Identification of an ectopic periorbital lymph node in two horses.

Background: To describe the clinical presentation and treatment of an ectopic periorbital lymph node in two young horses. Case Description: Two warm-blood horses were presented at the equine clinic of the University of Liège with a periorbital non-painful mass. Differential diagnosis included neoplasm (lymphoma), (sterile) abscess, cyst, ectopic lacrimal gland tissue, hematoma, adipose tissue, or ectopic lymphoid tissue. Information collected included physical and ophthalmic examination findings, results of the ocular and periocular ultrasound, surgical procedure, histopathology, and follow-up. Masses of 2 × 2 cm and 3 × 2 cm subcutaneous, ovoid, smooth, and firm mass were observed in the zygomatic region of the head. On ultrasound, the mass appeared as a hypoechoic subcutaneous structure. Cytology showed a mixed lymphocytic cell population. No abnormal mitotic activity was observed. Histopathology revealed a chronic markedly reactive lymph node. Conclusion: To the authors' knowledge, this is the first description of periorbital ectopic lymph nodes in veterinary medicine. Ectopic lymph nodes should therefore be included in the differential diagnosis of periocular masses in animals. Surgery was easily performed and was curative.

Retinal detachment secondary to vitreoretinopathy in two closely related warmblood horses.

BACKGROUND: To describe the clinical, diagnostic imaging, and histopathological findings of two visually impaired closely related horses and to identify a possible cause. CASE DESCRIPTION: Two warmblood horses, with a common dam and sire, were presented to the ophthalmology department of Liège for investigation of impaired vision. Information collected included physical and ophthalmic examination findings, results of ocular ultrasound, electroretinogram, magnetic resonance imaging (MRI), and histopathology. Ophthalmic examination, ocular ultrasound and MRI revealed a complete retinal detachment (RD) in the left eye and vitreous synaeresis in both eyes of both horses. Electroretinograms showed a normal response in both right eyes but a total loss of the retinal response in their left eyes. Histopathologic examination revealed multifocal retinal dysplasia in both left eyes. CONCLUSION: In these two horses, RD has likely been caused by the congenital posterior segment abnormalities of the vitreous and the retina. A vitreoretinopathy is highly suspected and is possibly hereditary in these closely related siblings.

Onset and duration of cis-atracurium neuromuscular block during fentanyl and lidocaine infusions in isoflurane-anaesthetised dogs.

BACKGROUND: This retrospective study assessed the onset and duration of the neuromuscular block (NMB) induced by cis-atracurium 0.15 mg/kg intravenously with and without fentanyl or lidocaine infusions in 45 isoflurane-anaesthetised dogs. METHODS: Dogs with neuromuscular function assessed by a calibrated train-of-four (TOF) monitor with stimulation (every 13 s) of the peroneal nerve were included. The onset and duration of the NMB were defined as the time from cis-atracurium administration until TOF=0 and the time during TOF=0 display, respectively. RESULTS: The NMB onset was shorter during fentanyl (mean±sd) (1.9±0.7 minutes; P=0.0042) and lidocaine (2.0±0.7 minutes; P=0.0154) compared with control (2.9±0.8 minutes). The NMB duration was shorter in the fentanyl (27.5±7.3 minutes; P=0.0491), but not in the lidocaine group (32.3±6.9 minutes; P=0.0790), compared with control (33.7±9.1 minutes). The NMB onset was poorly but significantly correlated with the dose of fentanyl and lidocaine administered before cis-atracurium (r=-0.3396; P=0.0225). The fentanyl and lidocaine groups received more crystalloid and colloid boluses than the control. CONCLUSIONS: Fentanyl and lidocaine shortened the NMB onset and the former decreased the NMB duration. Further prospective studies are required to clarify whether this was associated with an indirect decrease in blood pressure or a direct interaction between cis-atracurium and fentanyl and lidocaine.

Orbital compartment syndrome resulting in unilateral blindness in two dogs.

Orbital compartment syndrome (OCS) is described in humans as an acute rise in intraorbital pressure following a severe and rapidly evolving orbital affection. It includes orbital oedema, haemorrhage or infection causing a marked reduction in local blood perfusion, and severely affecting the orbital neurovascular structures. If not promptly recognised and treated, it results in irreversible blindness. It is one of the rare ophthalmic surgical emergencies, requiring lateral canthotomy and cantholysis. This case report describes two canine cases of complex orbital, periorbital and facial abscesses resulting in OCS and permanent unilateral blindness diagnosed by ultrasonography, computed tomography and electroretinography.

Use of Nasotracheal Intubation during General Anesthesia in Two Ponies with Tracheal Collapse.

Ponies with tracheal collapse may have an increased anesthetic risk due to airway obstruction during induction and recovery. To our knowledge, there are no anesthetic descriptions of these patients, despite a reported 5.6% incidence and 77% mortality rate. Two Shetland ponies with tracheal collapse, a 12-year-old male (pony 1) and a 27-year-old female (pony 2), were referred for right eye enucleation due to a perforating corneal ulcer and severe recurrent uveitis, respectively. Pony 1 was stressed, had lung stridor and hyperthermia, and developed inspiratory dyspnea with handling. Radiography confirmed collapse of the entire trachea as well as inflammation of the lower airways. Corticosteroids and bronchodilators were administered by nebulization for 1 week before surgery. Pony 2 had a grade III/VI mitral murmur and a clinical history of esophageal obstructions and tracheal collapse requiring tracheostomy. Both ponies were premedicated with acepromazine and xylazine; anesthesia was induced with midazolam and ketamine. Nasotracheal intubation was performed in left lateral recumbency with extension of the neck and head and was guided by capnography. The nasotracheal tube consisted of two endotracheal tubes attached end-to-end to create a tube of adequate length and diameter. Pony 2 was orotracheally intubated during surgery and later reintubated with a nasotracheal tube. Anesthesia was maintained with isoflurane using volume-controlled ventilation. Analgesia was provided by a retrobulbar blockade with mepivacaine and lidocaine. Cardiovascular support consisted of lactated Ringer's solution and dobutamine. After surgery, the ponies were administered xylazine and supplemented with oxygen through the nasotracheal tube. Recovery was assisted by manual support of the head and tail. Successful extubation was achieved following butorphanol administration after approximately 1 h in standing position. Both ponies were discharged from the clinic a few days after surgery.