Assessment of the utility of using intra- and intervertebral minimum sagittal diameter ratios in the diagnosis of cervical vertebral malformation in horses
ABSTRACT Cervical vertebral malformation is one of the most common causes of ataxia in horses. The most important factor in the diagnosis of cervical vertebral malformation is the identification of cervical vertebral canal stenosis, but published data for minimum sagittal diameter ratios in adult horses are only available for C4-C7 intravertebral sites. Intra- and intervertebral sagittal diameter ratios at C2-C7 were evaluated in 26 ataxic horses, for which a complete clinical and neuropathological evaluation was undertaken. Eight of these horses were diagnosed with cervical vertebral malformation. In these horses the majority of compressive lesions were intervertebral. The mean sagittal diameter ratios of horses with cervical vertebral malformation were significantly smaller than those of horses without cervical vertebral malformation, and for an individual horse in our study, the site with the smallest intervertebral sagittal diameter ratio was always the site at which the spinal cord was compressed. Mean sagittal diameter ratio intravertebral site measurements of horses with cervical vertebral malformation were smaller than those of horses without cervical vertebral malformation; however, the site of compression could not be predicted from the data. For our dataset, horses with a sagittal diameter ratio of < or = 0.485 at any inter- or intravertebral site could be correctly classified as having cervical vertebral malformation, and sagittal diameter ratio measurements were an effective tool to identify at least one site of compression in an individual case.
Article: Cervical radiology02/2010; 22(2). DOI:10.2746/095777309X478671
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ABSTRACT: Great Danes are predisposed to osseous-associated cervical spondylomyelopathy (Wobbler syndrome). The first aim of this prospective study was to compare values measured using previously published intravertebral and intervertebral ratio methods and a novel ventrodorsal ratio method in radiographs of clinically normal and affected Great Danes. The second aim was to determine whether these ratios could be used as predictors of sites of spinal cord compression based on magnetic resonance imaging (MRI). Thirty dogs (15 normal, 15 affected) were prospectively enrolled. Lateral and ventrodorsal radiographs were obtained and six measurements were recorded from C3-T1. For each vertebral location, intravertebral ratios and intervertebral ratios were calculated from lateral views, and the ratio of the distance between the articular process joints vs. vertebral body width (novel ventrodorsal ratio) was calculated from ventrodorsal views. Values for these three ratios were compared, by vertebral location and dog group. Intravertebral and intervertebral ratios did not differ between dog groups. The ventrodorsal ratio was significantly smaller in affected Great Danes at C5-6 (P = 0.005) and C6-7 (P < 0.001). The ventrodorsal ratio was significantly associated with MRI presence of spinal cord compression. For each 0.1 unit increase in this ratio value, there was a 65% decrease in the odds of spinal cord compression being present at that site, independent of vertebral location (P = 0.002). Findings from this study supported use of the novel ventrodorsal ratio as an initial radiographic screening method for Great Danes with suspected cervical spondylomyelopathy.Veterinary Radiology & Ultrasound 04/2014; 55(5). DOI:10.1111/vru.12159 · 1.26 Impact Factor
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ABSTRACT: Toolara State Forest is the largest exotic commercial pine plantation located in the Sunshine Coast area of Queensland. Due to an abundant supply of resources, there is a significant population of feral horses (Equus caballus), which is facing an increased risk of overpopulation. Evidence from previous surveys suggests that over ten years the population has increased from 180 to 800 individuals, which could potentially lead to welfare issues. The objective of the study was to characterise population dynamics and growth in order to define the needs for long-term population control and management. The feral horse population was studied in the forest by direct observations from September 2011 through April 2012. Population composition, stability of harems, habitat preferences and foaling rate for 2011/2012 breeding season were estimated. Observations were performed over one week in each month. Horses were identified on the basis of body colour, natural head and leg markings, gender, age and group associations. The composition and location of horse groups was recorded at each observation. Detailed observations were made on a focal population of 319 horses, consisting of 54 breeding groups (277 horses), 15 bachelor groups (35 individuals) and 4 mares and their offspring groups (7 horses), which occupied the study area of 110 km2. Gender ratio of adult horses was slightly biased towards females; with the ratio being 1.0:0.85 females to males. The age structure of the focal population constituted of 68.3% adult horses, 10.3% juveniles (2-3 years old), and 6.89 yearlings. Foals made 14.42% of the total population in 2011/2012 breeding season. Based on observation of live foals present at foot (n=46), the foaling rate was calculated at 39%. The temporal trend indicated that reproduction in the focal population was seasonal, with the greater part of foaling events occurring between September and February; and reaching two foaling peaks in September (27%) and in January (23%), respectively. Estimated foal survival was 89% (n = 41), of which 60% (n=3) of recorded mortalities occurred in younger foals (age 0 to 1 month).The reproduction values for 2011/2012 breeding season reached 0.21 offspring per adult horse. Using finite rate of population increase, we estimated that the maximum rate for the focal population growth was 21.1% and was similar to estimates proposed for other feral horse populations. Based on our data, such as the female biased gender ratio, the large number of horses that are in reproductive age, and the potential of the population to grow per year at a rate of 21%, this population of feral horses in Toolara State Forest has the ability to increase considerably and will require active management to control numbers.Australian and New Zealand College of Veterinary Scientists, Gold Coast, Australia; 01/2012