Quantitative Analysis of the Intramedullary Arterial Supply of the Feline Tibia: is There a Causal Relationship to Delayed and Nonunion Fracture Healing?

Clinical observations suggest that feline tibial fractures are prone to delayed union and nonunion healing complications. This study sought to quantitatively describe the intramedullary arterial supply of the adult feline tibia and determine if the arterial supply is different from that of adult small dogs, who seemingly do not exhibit the same rates of delayed and nonunion fracture healing. Our null hypothesis was that the intramedullary arterial density and diameter of the nutrient artery in the adult feline tibia was the same as the age and size matched dog. Using microvascular injection and modified Spalteholz techniques, cadaveric feline and canine pelvic limbs were prepared to characterize the intramedullary arterial supply of the tibia. Processed specimens were evaluated using the ImageJ morphometric program. Statistical comparisons were made between cats and dogs for the intramedullary arterial density and diameter of the nutrient artery. There was no significant difference in the intramedullary arterial density between dog and cat tibiae. The feline nutrient artery diameter (0.5497 ± 0.0552mm) was significantly different than the canine nutrient artery (0.2976 ± 0.0423mm) in the distal section of bone. Dogs subjectively exhibited more branching vessels in the distal and mid-diaphyseal bone sections. Delayed fracture healing in the feline tibia does not appear to be due to diminished intramedullary arterial supply. However, a lack of diffuse arborization of the arterial supply to the cortex of the mid-diaphyseal and distal feline tibia may explain, in part, why feline tibial delayed or nonunions may be more common than those in dogs.Veterinary Pathobiology Science

Flexible nine-channel photodetector probe facilitated intraspinal multisite transcutaneous photobiomodulation therapy dosimetry in cadaver dogs

Noninvasive photobiomodulation therapy (PBMT) of spinal cord disease remains speculative due to the lack of evidence for whether photobiomodulatory irradiances can be transcutaneously delivered to the spinal cord under a clinically acceptable PBMT surface irradiation protocol. We developed a flexible nine-channel photodetection probe for deployment within the spinal canal of a cadaver dog after hemilaminectomy to measure transcutaneously transmitted PBMT irradiance at nine sites over an eight-cm spinal canal length. The probe was built upon a 6.325-mm tubular stem, to the surface of which nine photodiodes were epoxied at approximately 1 cm apart. The photodiode has a form factor of 4.80 mm×2.10 mm×1.15 mm (length×width×height). Each photodiode was individually calibrated to deliver 1 V per 7.58 μW/cm2 continuous irradiance at 850 nm. The outputs of eight photodiodes were logged concurrently using a data acquisition module interfacing eight channels of differential analog signals, while the output of the ninth photodiode was measured by a precision multimeter. This flexible probe rendered simultaneous intraspinal (nine-site) measurements of transcutaneous PBMT irradiations at 980 nm in a pilot cadaver dog model. At a surface continuous irradiance of 3.14 W/cm2 applied off-contact between L1 and L2, intraspinal irradiances picked up by nine photodiodes had a maximum of 327.48 μW/cm2 without the skin and 5.68 μW/cm2 with the skin.Electrical & Computer EngineeringVeterinary Clinical Science