Long-term outcome of autologous fascia lata grafting with conjunctival flap overlay in horses with ulcerative keratitis and keratomalacia.

OBJECTIVES: To describe the technique, postoperative complications, and outcome after autologous fascia lata grafting with conjunctival flap overlay in horses with ulcerative keratitis and keratomalacia. STUDY DESIGN: Retrospective case series. ANIMALS: Eleven horses with ulcerative keratitis and keratomalacia. METHODS: Horses included had undergone fascia lata grafting with conjunctival flap overlay due to impending or recent corneal perforation. Preceding therapy, lesion characteristics, postoperative complications, and short- and long-term outcomes were recorded. RESULTS: Postoperative complications included complete (1/11) or partial (2/11) dehiscence of the conjunctival flap and fascia lata graft, postoperative pneumonia (1/11), intermittent hypercreatinemia (2/11) and mild uveitis after trimming of the conjunctival flap (9/10). The donor sites healed without complications (11/11). A satisfactory short-term outcome (at cessation of medical therapy) was achieved in all horses (11/11). Long-term follow-up (median 29 months, range 7-127 months) was available for 10/11 horses. A comfortable eye with functional vision was achieved in 9/10 horses with long-term follow-up, including 3/4 horses with prior corneal perforation and 1/11 horses in which the fascia lata graft completely dehisced 15 days after surgery. Enucleation was required in a single horse (1/10) after phthisis bulbi developed 7 months postoperatively. CONCLUSION: Fascia lata grafting with conjunctival flap overlay appears to be a viable solution for globe preservation in horses with ulcerative keratitis and keratomalacia. Long-term ocular comfort with functional visual outcomes can be achieved in most cases with limited concerns for donor site morbidity while bypassing acquisition, storage or lesion-size limitations related to other biomaterials.

Duration of action of mepivacaine and lidocaine in equine palmar digital perineural blocks in an experimental lameness model.

OBJECTIVE: To establish and compare the onset and duration of action of 2 local anesthetics based on objective lameness and skin sensitivity assessment. STUDY DESIGN: Interventional crossover experimental trial with balanced randomization. ANIMALS: Eight horses. METHODS: Reversible forelimb lameness was induced in 8 horses. A palmar digital nerve block (PDNB) was applied with mepivacaine or lidocaine (both 2%). Quantitative lameness and skin sensitivity data were collected with an inertial sensor system and a force gauge, respectively. The times to lameness resolution/skin desensitization (T1), consistent lameness detection/partial return of skin sensitivity (T2), and complete return of lameness/skin sensitivity (T3) were determined and compared between treatments and assessment methods. RESULTS: Mepivacaine blocks resolved lameness in 8/8 horses, compared to 3/8 horses with lidocaine blocks. Both agents led to skin desensitization in 8/8 horses. Skin desensitization occurred sooner than lameness resolution after mepivacaine (P = .047). Duration of action was longer with mepivacaine than lidocaine (mean T3_lameness mepivacaine 366 minutes, lidocaine 113 minutes (P = .038); T3_skin mepivacaine 195 minutes, lidocaine 63 minutes [P ≤ .001]). Skin sensitivity returned sooner than lameness after lidocaine block at T3 (P = .015). CONCLUSION: The use of lidocaine in PDNBs for the purpose of lameness diagnosis should be reassessed, as it may not resolve lameness despite loss of skin sensation. Mepivacaine is superior, with a reliable onset and longer duration of action. Skin desensitization as an indicator for the onset of action or effectiveness of PDNBs for mepivacaine and lidocaine, or as a measure of the duration of action of lidocaine PDNBs should be interpreted with caution.

In-vitro comparison of LC-DCP- and LCP-constructs in the femur of newborn calves - a pilot study.

BACKGROUND: To compare the biomechanical in-vitro characteristics of limited-contact dynamic compression plate (LC-DCP) and locking compression plate (LCP) constructs in an osteotomy gap model of femoral fracture in neonatal calves. Pairs of intact femurs from 10 calves that had died for reasons unrelated to the study were tested. A 7-hole LC-DCP with six 4.5 mm cortical screws was used in one femur and a 7-hole LCP with four 5.0 mm locking and two 4.5 mm cortical screws was used in the corresponding femur. The constructs were tested to failure by cyclic compression at a speed of 2 mm/s within six increasing force levels. RESULTS: The bone-thread interface was stripped in 21 of 80 cortical screws (26.3%) before a pre-set insertion torque of 3 Nm was achieved. Only 3 corresponding intact pairs of constructs could be statistically compared for relative structural stiffness, actuator excursion and width of the osteotomy gap. Relative structural stiffness was significantly greater, actuator excursion and width of the osteotomy gap were significantly smaller in the LCP constructs. While failure occurred by loosening of the screws in the LC-DCP constructs, locking constructs failed by cutting large holes in the soft distal metaphyseal bone. CONCLUSIONS: An insertion torque sufficient to provide adequate stability in femurs of newborn calves could not be achieved reliably with 4.5 mm cortical screws. Another limiting factor for both constructs was the weak cancellous bone of the distal fracture fragment. LCP constructs were significantly more resistant to compression than LC-DCP constructs.