Effect of Volumes of Solutions on Intraocular Pressure During Intravitreal Injection of Low Dose Gentamicin in Horses With Recurrent Uveitis: A Randomized Controlled Study.

Horses with recurrent uveitis can be treated by intravitreal injection of low dose gentamicin under sedation and after local anesthetic techniques including the retrobulbar nerve block. Since it is reported that retinal degeneration can be secondary to an acute increase of intraocular pressure (IOP), the current randomized controlled study was carried out in order to investigate the changes in IOP following retrobulbar anesthesia, with two different volumes of local anesthetic (lidocaine) solution (10 and 5 mL), and intravitreal injection of 6 mg gentamicin in two different volumes of solution (0.3 and 0.15 mL). Multivariate regression showed that IOP was significantly lower in the pathologic eye at baseline (estimated effect size -6.1 mmHg; P = .0001) and after sedation (estimated effect size -9.4 mmHg; P < .0001). The IOP was significantly higher after a 10 mL block (P .0002) but this effect was very small (+0.5 mmHg). There was no significant difference in IOP after the injection of 0.15 or 0.3 mL solution of gentamicin. There was no significant combined effect of the volume of local anesthetic used for the block and the volume of the gentamicin solution. Since the expected anesthetic effects (desensitization and akinesia) were met in all cases, the smaller volume of 5 mL of lidocaine solution would be preferable for retrobulbar block for intravitreal injections, while intravitreal injections volumes of 0.15 and 0.30 mL can be used indifferently.

Use of Negative Pressure Wound Therapy in the Treatment of Limb Wounds: A Case Series of 42 Horses.

Traumatic limb injuries are common in horses. Negative pressure wound therapy (NPWT) has been proven to promote wound healing in human medicine. It has also been described for the treatment of wounds in horses. In this retrospective study, clinical records of 42 (n = 42) animals were assessed. Categories of wounds, duration of NPWT application, frequency of resetting the NPWT device, technical complications, and tolerance to the procedure were recorded. 42 wounds were classified as bony (n = 15; 36 %), articular (n = 14; 33 %), tenosynovial (n = 9; 21%), muscular (n = 2; 5%) and cutaneous (n = 2; 5 %). NPWT was used to help (1) first intention healing by preoperative (n = 3; 7 %) or postoperative (n = 7; 17%) application, (2) second intention healing (n = 31; 74%), and (3) delayed primary closure (n = 1; 2%). Duration of NPWT application ranged from 2 to 36 days (mean 11.5), with the system staying in place for periods ranging from 1 to 7 days (mean 4.5). In 69% (n = 29) of the cases, healing was considered satisfactory at discharge. 26 % (n = 11) of horses were discharged whilst ideally NPWT should have been continued. 2 animals (n = 2; 5%) were euthanized after surgery due to unrelenting pain. The procedure was well tolerated except in 1 horse who showed signs of discomfort at the first application. This study demonstrated that NPWT with long periods of application can be used successfully to manage various types of limb wounds.

DDB2 Genetic Risk Factor for Ocular Squamous Cell Carcinoma Identified in Three Additional Horse Breeds.

Squamous cell carcinoma (SCC) is the most common cancer affecting the equine eye. A missense variant within the gene damage-specific DNA binding protein 2 (DDB2 c.1013C>T, p.Thr338Met) was previously identified as a causal recessive genetic risk factor for the development of ocular SCC within Haflingers, Belgian Draft horses, and Rocky Mountain Horses, but not in the Appaloosa or Arabian breeds. This study aimed to evaluate three cases of ocular SCC in additional breeds and determine if DNA testing for the DDB2 variant in warmblood horses and Connemara ponies is warranted. Histopathology confirmed ocular SCC in all three cases and DNA testing confirmed each horse was homozygous for the DDB2 risk factor. The DDB2 risk allele frequency was estimated to be 0.0043 for Holsteiners (N = 115), 0.014 for Belgian Warmbloods (N = 71), and 0.22 for Connemara Ponies (N = 86). Taken together these data support using DNA testing for DDB2 in Connemara Ponies to assist in mate selection and clinical management. Given the low observed allele frequencies in both the Holsteiner and Belgian Warmblood breeds and that the case under investigation was a warmblood cross-bred, evaluating additional SCC affected warmbloods is warranted to fully determine the importance of DDB2 genotyping as a risk factor in warmblood breeds.

Use of Intravitreal Injection of Gentamicin in 71 Horses With Equine Recurrent Uveitis.

We report a retrospective evaluation of intravitreal gentamicin (6 mg in 0.3 mL solution) injection in 71 horses with equine recurrent uveitis between 2010 and 2016. Aqueous flare and hyalitis were scored at the baseline in all horses, then at 15, 30, 60, 90, 180, 365, and 730 in 37, 46, 30, 25, 22, 18, and 11 horses, respectively. Forty-two animals had a global score of inflammation (sum of scores for aqueous flare and hyalitis) of zero at the last examination (number of re-examinations per horse ranged from 1 to 5). Among the 29 remaining horses, four were not reassessed after the intervention. The individual inflammation scores of the remaining 25 horses improved in 21 cases, whereas it slightly deteriorated in four cases (number of re-examinations ranged from 0 to 6). Ocular hypotension, lens opacities, and retinal folds were observed, respectively, in 92%, 78%, and 28% of the 71 eyes at the baseline, and in 80%, 90%, and 36% of the 11 eyes re-evaluated at 2 years. A telephone inquiry about all horses among owners and referring veterinarians conducted in 2016 at least 6 months after the more recent injections indicated that 70 horses did not develop a new observable episode of inflammation and did not need ocular medication. Although the results of this study should be discussed with reservation, it indicated that low-dose intravitreal injection of gentamicin could be a useful treatment to maintain ocular quiescence in equine recurrent uveitis.

Computed tomography to identify preoperative guidelines for internal fixation of the distal sesamoid bone in horses: an in vitro study.

OBJECTIVE: To assess the reliability of computed tomography (CT) to identify the direction of implant insertion for cortical screws along the longitudinal axis of intact (nonfractured) distal sesamoid bones. STUDY DESIGN: In vitro study. SAMPLE POPULATION: Cadaveric paired equine forelimbs (n=16). METHODS: Insertion of a cortical screw in lag fashion along the longitudinal axis of intact (nonfractured) distal sesamoid bones was evaluated in 2 groups (3.5 and 4.5 mm) of 8 paired limbs. In each group, the direction of the distal sesamoid bone was determined by CT (Equine XTC 3000 pQCT scanner). Screw placement was verified by specimen dissection. Implant direction was considered satisfactory if the entire screw length was within the distal sesamoid bone and not damaging the articular or flexural surfaces. RESULTS: In our sample and according to our criteria, the proportion of satisfactory direction of screws was 0.63 (5/8) for 4.5 mm implants, and 0.87 (7/8) for 3.5 mm implants. CONCLUSIONS: CT is a useful imaging modality to identify anatomic landmarks for insertion of a 3.5 mm cortical screw in the distal sesamoid bone.

Use of computed tomography in standing position to identify guidelines for screw insertion in the distal phalanx of horses: an ex vivo study.

OBJECTIVES: To compare the precision of radiography and computed tomography (CT) preoperatively in the standing position for identification of guidelines for screw insertion in the distal phalanx, and to identify whether standing CT might improve operative time compared with preoperative radiographic planning. STUDY DESIGN: Experimental ex vivo study. ANIMALS: Cadaveric equine thoracic limb pairs (n=10). METHODS: Insertion of a 4.5 mm cortex screw in lag fashion into an intact distal phalanx was evaluated in 2 groups (n=10) of cadaveric equine thoracic limbs. In 1 group, the site, direction, and length of the implant were determined by radiography, and in the other group, by CT. Accuracy of screw placement was verified by specimen dissection. Outcomes were (1) absence of penetration of the articular surface, the solar surface, or the semilunar canal (2) appropriate length and direction of the screw. Surgical time was also measured. RESULTS: No screw penetrated the articular surface, the solar surface, or the semilunar canal in either group. CT was more accurate to identify guidelines for screw insertion (U=23.50, P=.049). With CT, surgical time (mean, 7.7 minutes) was significantly shorter (U=0.000, P=.000) than with radiography (mean, 12.7 minutes). CONCLUSION: Standing CT can be used to accurately determine anatomic landmarks for screw insertion in lag fashion in sagittal fractures of the distal phalanx. CLINICAL RELEVANCE: This study has a clear clinical relevance for improved internal fixation of sagittal fractures of the distal phalanx.

Endoscopic resection of dorsal spinous processes and interspinous ligament in ten horses.

OBJECTIVE: To describe endoscopic surgical subtotal resection of the dorsal spinous processes (DSP) and interspinous ligament in horses. STUDY DESIGN: Descriptive clinical study. ANIMALS: Adult horses (n=10) with back pain and impinging dorsal spinous processes METHODS: Diseased portions of DSP and interspinous ligament were resected by endoscopic surgery, using Destandau Endospine to create a surgical space and provide triangulation for the endoscope, suction cannula, and surgical instruments. Medical records of 10 horses with pain attributable to DSP pathology treated by endoscopic resection of DSP were reviewed to determine intra- and postoperative complications and outcome. RESULTS: Affected portions of DSP were successfully resected with minimal hemorrhage. Limited periosteal reaction was noticed after 3 months in 2 horses. Nine horses had no complications and returned to full work within 8 weeks; 1 developed a subcutaneous abscess, which was successfully managed, and returned to work after 3 months. Surgical resection improved presenting clinical signs and owner's complaint although 2 horses did not return to previous performance levels. CONCLUSION: Resection of DSP and interspinous ligament can be successfully performed endoscopically in horses. Hemorrhage was minimal but reduced visibility. Complications were minimal and most horses returned to work by 8 weeks. CLINICAL RELEVANCE: Endoscopic resection of DSP is a safe and reliable surgical procedure in horses.