Safety and accuracy of blind vs. ultrasound-guided dorsal retrobulbar nerve blocks in horses-A cadaveric study.

OBJECTIVE: There is limited knowledge regarding the safety and accuracy of ultrasound-guided retrobulbar nerve blocks in horses. The aim of this study was to compare these parameters between blind and ultrasound-guided injection techniques for the dorsal retrobulbar nerve block in horses. METHODS: Equine cadaver heads were used to inject the retrobulbar space with contrast medium (CM). Injections were performed either blindly based on anatomic landmarks (blind group, n = 44) or under ultrasonographic guidance (US-group, n = 44), equally divided between an experienced and unexperienced operator. Needle position and distribution of CM were assessed with computed tomography imaging and evaluated by a board-certified veterinary diagnostic imager blinded to the technique. Safety and accuracy of both techniques were compared. RESULTS: Ocular penetration was observed in two cases (n = 2/44) in the blind group but not in the US group (n = 0/44). No intrathecal, intraneural, or intravascular injections were seen in either group. Safety was significantly improved in the US group (p = .026). There was no statistically significant difference between the groups regarding the accuracy of the injection. Excellent accuracy was achieved more often with the ultrasound-guided technique (n = 11/22) than with the blind technique (n = 7/22) when performed by the unexperienced operator, but this difference was not statistically significant. CONCLUSION: To prevent globe-threatening complications and improve the safety of the injection, we recommend using the ultrasound-guided injection technique for the dorsal retrobulbar nerve block.

Photodermatitis and ocular changes in nine horses after ingestion of wild parsnip (pastinaca sativa).

BACKGROUND: Primary photosensitization rarely occurs in horses and can easily be misinterpreted. Descriptions of the disease in horses after ingestion of parsnip are lacking. The aim of this case series was to describe the dermatological and ocular changes due to photosensitization and to raise awareness of parsnip being a possible aetiologic agent. CASE PRESENTATION: Nine horses from three different stables in Berlin and Brandenburg, Germany, presented variable degrees of erythema, scaling, crusting and necrosis of unpigmented skin at the head and prepuce. Horses were of different breeds with a median age of 15 ± 5.9 years. A mild leukocytosis was diagnosed in 1/9 horses at admission. Analyzed liver enzymes were within the reference ranges in all horses. Ocular changes were diagnosed as follows: blepharitis (3/9), conjunctivitis (7/9), corneal edema without additional signs of keratitis and/or uveitis (2/9), corneal edema with signs of uveitis (1/9) and photophobia (4/9). One horse developed a fluorescein positive corneal erosion. Skin biopsy (1/9) revealed a moderate to severe acute, eosinophilic and lymphocytic dermatitis with dermal edema and vasculitis. All stables housing these patients fed hay from the same distributer. Analyzed hay samples showed high contents of wild parsnip (plants, seeds, roots). Wild parsnip is widespread in Europe and contains furocoumarins, a family of photodynamic pigments, which may cause primary photodermatitis, keratoconjunctivitis and uveitis. Horses were treated according to severity of clinical symptoms systemically with flunixine meglumine (1.1 mg/kg BW 1-2x/day) or prednisolone (1 mg/kg BW 1x/day). Topically, either gentamicin (3x/day), dexamethasone (2-3x/day) and/or atropine (1x/day) were used. Skin care was provided with almond oil or dexpanthenol (2x/day). All horses were kept in a dark environment or were treated with sunscreen and facemasks. Duration of treatment varied from 6-30 days (median 11.3 days). CONCLUSION: Ingestion of wild parsnip (Pastinaca sativa) can induce primary photosensitization with dermatitis and ocular injury in horses. In times of extreme weather, hay may alter in botanical composition, resulting in high amounts of uncharacteristic plants causing novel problems.

Radiographic measurements of the hooves of normal ponies.

Knowledge of the normal radiographic anatomy of the equine foot and the relationship between the distal phalanx and the hoof capsule is imperative for objective assessment of hoof health. Little information is available for the hooves of ponies. The aim of this study was to establish a database of reference values for normal ponies and to investigate the relationship between the height at the withers and radiographic measurements of the hooves. Radiographic examinations were performed on 81 ponies, ranging from 81.5 to 148.0 cm height at the withers, immediately after foot trimming. Eighteen parameters were measured in the lateromedial view (front and hind feet) and 13 parameters were measured in the dorsopalmar view (front feet). Most linear measurements had a strong positive correlation with the height at the withers. The influence of height on angular measurements was weak. A linear regression model was adopted to enable calculation of reference values for a defined height at the withers. Left feet were longer in 72% of front feet and 67% of hind feet. The medial part of the hoof was more upright generally, but the medial hoof wall was shorter only in the right front feet. The front feet tended to be more upright than the hind feet. Compared to height at the withers, the hooves of ponies were relatively larger than the hooves of adult Warmblood horses investigated in a comparable study. The present study provides a database for farriers and veterinarians for hoof conformation, on the basis of which hoof preparation and an accurate diagnosis of lameness can be made.