Application of canine pedicle screw and rod fixation system in the lumbar 1 and 2 vertebral body of mongrel dogs

Vertebral fractures and luxation (VFL) is a common spinal cord disorder in dogs, mostly affect the thoracolumbar region. Canine pedicle screw and rod fixation (CPSRF) system is a modified system from pedicle screw and rod fixation system (PSRFS), a device tailored for canine spine that offers a great alternative to commercially available implants. The aims of this study were; (1) to document VFL cases in University Veterinary Hospital, Universiti Putra Malaysia (UVH, UPM), (2) to determine the optimal corridor implantation of CPSRF in medium size dogs and (3) to examine gross and microscopic lesion to the vertebrae and spinal cord after CPSRF system implantation. Retrospective evaluation showed 49% of spinal cord cases were contributed by VFL. Adult, outdoor and intact male dog were prone to VFL. Nearly 40% of VFL cases were represented by local dogs (p <0.01) with the odds of VFL were four times higher than pure breed dogs (OR = 4.21, 95% CI 1.32-13.25). The most common site for VFL were at T13- L2 hence L1 and L2 region were chosen for the experiment. Two screws of 16mm and 20mm and rod of 40mm and 45mm were inserted into the pedicles of L1 and L2 in six dogs. Safe implantation angle for 16mm screw at L1 were 52. 67°±10.40º and at L2 were 58.59°±7.72º. The mean distance of 16mm screw tips to aorta and caudal vena cava at L1 were 9.21±3.67mm and 18.96±5.17mm while average distance for 20mm were 8.91±2.45mm and 20.78±6.32mm. At L2, the distance of 16mm screw tips to aorta and caudal vena cava were 11.32±1.47mm and 19.26±5.12mm while average distance of 20mm were 10.23±2.40mm and 21.15±1.84mm at L2. No gross lesion was found on the vertebrae although minimal microfractures was found in all vertebral samples through histological examination. None of the spinal cord had penetrative or lacerative injury however longer observation period was required to assess the long-term effect of the implant. Findings from computed tomography scan and histological examination suggest that 16mm screw is suitable for medium sized dog with safe implantation corridor between at 58.42°±7.25°. This study had shown that CPSRF is feasible for medium sized dogs however long-term study is required to determine stability and durability of the system

A retrospective study of vertebral fracture and luxation in dogs presented to University Veterinary Hospital, Universiti Putra Malaysia in 2015 to 2017

To date, there is data paucity on canine vertebral fracture and luxation (VFL) in the local setting. Therefore, it was hypothesized that the geographical location and stray dog population would influence VFL cases in the University Veterinary Hospital, Universiti Putra Malaysia (UVH, UPM). This study aimed to describe the incidence and characteristics of VFL in dogs presented to UVH, UPM. Medical records, including radiographic images of 74 dogs between 2015 to 2017, were reviewed. VFL dominated the spinal cord disease in dogs at 49% (n = 36/74), exceeding intervertebral disc disease (IVDD) and acute noncompressive nucleus pulposus extrusion (ANNPE). Half of VFL cases were contributed by intact male, small breed dogs aged more than one-year-old, with 52% (n = 11/19) of cases caused by vehicular accidents. Almost two-thirds (n = 21/36) of dogs with VFL were outdoor or stray dogs, and the Th3-L3 region was the most susceptible (52%, n = 19/36) for VFL. More than 70% (n = 25/36) of the patients had unstable fractures, highly associated with severity. In conclusion, the occurrence of VFL in UVH, UPM is three times higher than reported in western countries and most likely contributed by a large number of outdoor and stray dogs

Canine vertebral screw and rod fixation system in dogs

Bone plates and screws are often recommended to fix vertebral fracture and luxation in dogs although several complications had been reported. The canine vertebral screw and rod fixation (CVSRF) system, a device tailored for the canine spine, is a modified system from the human pedicle screw. This study aimed to determine the optimal corridor implantation of CVSRF and to investigate the potential trauma to the vertebrae and spinal cord in medium-sized dogs. Two screws of 16 mm and 20 mm and rods of 40 mm and 45 mm in length were inserted into the pedicles of L1 and L2 in six dogs. Safe implantation angles for 16 mm screw were 52.67° ± 10.40ºand 58.59° ± 7.72ºat L1 and L2, respectively. The angle of the 20 mm screw at L1 was recorded at 56.03°±5.34ºand 55.67° ± 2.89ºat L2. No gross and histological lesion was found on the spinal cord and vertebrae although minimal microfractures of the vertebrae were observed histologically. Findings from this study suggest that CVSRF is feasible for medium-sized dogs using 16 mm screws, however, a long-term study is required to determine the stability and durability of the system