2 3 6 8 n = 43; 86 joints.months. Subsequent progression was usually followed by regression and resolution, the appearance returned in most cases to normal at age 8 months. At 5 months, 20% of the stifles were abnormal, but at 11 months this percentage had decreased to 3%. Normal and abnormal appearances were permanent from age 8 months.Osteochondrosis of the main predilection sites in the hock and stifle develops very early in life. The majority of the lesions were temporary, the 'age of no return' was 5 months for the hock and 8 months for the stifle.

The closure of the body wall defect at the umbilicus was studied in relation to the development of umbilical hernias in a group of 44 normal foals, 25 of which were followed from birth until five months of age, and 19 from birth until 11 months of age. At birth, 19 of the foals had a defect in the body wall at the umbilicus that was termed a 'palpable umbilical ring'. In 18 of them this defect disappeared within four days, but in the other the ring did not close and a hernial sac with abdominal contents was palpable. This foal was considered to be the only foal to have a truly congenital umbilical hernia. Twelve foals developed an umbilical hernia between five and eight weeks of age. The prevalence of umbilical hernias was much higher than in other studies, possibly owing to the prospective nature of the study.

No abstract

Summary: A retrospective study of 220 horses was performed to investigate the association between the clinical signs and the radiological findings of impinging dorsal spinous processes (DSPs) in warmblood sporthorses. For this purpose radiographic records were assessed to identify all horses that had undergone radiographic examination of the back as part of a pre-purchase examination between January 2009 and December 2012. The dorsal spinous processes of 239 horses were assessed and each dorsal spinous process was individually graded (0 -3) using a modified 4-group grading system appropriate for routine grading of dorsal spinous processes as part of a pre-purchase examination. Fifty-five percent (n =121) had no radiological abnormalities of the DSPs (grade 0). However, 26,4 % had at least one DSP with grade 1 impingement, 11,8 % had at least one DSP with grade 2 and 6,8 % had at least one DSP with grade 3. Follow-up information was obtained by telephone responses from owners or trainers. The horses were assessed at a mean follow up time after pre-purchase examination of 25,19 ±12,52 months. Based on the clinical signs included in the questionnaire answers horses were divided into two groups; i) thoracolumbar back pain and ii) no thoracolumbar back pain. Only 11,5 % (N = 23) of the 220 horses had shown thoracolumbar back pain. There was no significant association between gender, age or discipline and clinical signs of thoracolumbar back pain. High maximum DSP grade is associated with an increased risk of clinical signs. The specificity of a grade 3 DSP on radiographic screening at pre purchase examinations is high, however the sensitivity is low. This suggests that there is a high risk of clinical signs in horses with grade 3 DSPs and no warranty can be offered for absence of clinical signs for grade 0,1,2.Keywords: back pain / horse / kissing spines / pre purchase / radiology Citation: de Graaf K., Enzerink E., van Oijen P., Smeenk A., Dik K. J. (2015) The radiographic frequency of impingement of the dorsal spinous processes at purchase examination and its clinical significance in 220 warmblood sporthorses. Pferdeheilkunde 31, 461-468

Summary The aim of this study was to monitor the postnatal radiographic development of the proximal and distal double contours and the modelling of the shape of the proximal articular border. In mature horses, the proximal and distal contours of the navicular bone on dorsopalmar dorsoproximal‐palmarodistal oblique (upright pedal) radiographs are commonly visualised as 2 lines, one being the articular border and the second representing the border of the cortex facing the deep digital flexor tendon (flexor border). The shape of the proximal articular border may be concave, undulating, straight or convex in the mature animal. These shapes have been found to be hereditary and to constitute a predisposing factor in the pathogenesis of navicular disease. This predisposing role may result from a shape dependent distribution of the biomechanical forces exerted on this region. There is no agreement in the literature with respect to the moment when the navicular bone takes its mature radiographic appearance. Upright pedal radiographs of the left front foot of 19 Dutch Warmblood foals were made at age 1 month and subsequently at intervals of 4 weeks, until the age of 11 months. The distal double contour developed soon after birth and the radiographic visibility of the articular border improved from ill‐defined at 1 or 2 months to clear manifestation at 3 or 4 months. The proximal double contour developed later. The articular border became usually visible at age 3 or 4 months and was clearly visible from age 9 months. The mature shape of the proximal articular border usually became recognisable from age 7 months and was always obvious between 9 and 11 months. This development was associated with a gradual modelling of the lateral and medial extremities of the navicular bone. It was concluded that the navicular bone adopts its mature radiological appearance during the first year postpartum. Considering this early manifestation of the mature shape of the proximal articular border and its previously demonstrated inheritance, a force‐dependent development of this shape, as predicted by the trajectional theory/Wolffs law, is improbable. The predisposing role of this shape in the pathogenesis of navicular disease may therefore be explained by a shape‐dependent distribution of the biomechanical forces exerted on the navicular bone. Considering the potential application of these findings, from age 1 year shape determination enables identification of the individual and breed susceptibility for the development of navicular disease.

SummaryTo evaluate a novel tendon biopsy technique for use in the horse and to assess the effect of different exercise levels on the healing process of minimally damaged superficial digital flexor tendons (SDFT), 24 Dutch Warmblood foals were randomly divided into 3 equally sized groups one week after birth. One group was box rested, one group got box rest with additional enforced exercise, and one group got free pasture exercise. Biopsies from the peripheral region of the SDFT were taken at age 2 months using a new micro-biopsy technique. At age 5 months the foals were euthanized and samples from the biopsy site and a control site were harvested. Collagen fibrillar index (CFI, the total amount of collagen as a percentage of the measured area), mass-average diameter (MAvD, mean of the diameter versus area distribution) and collagen fibrillar diameter frequency (the distribution of collagen fibril sizes expressed as a percentage of the number of collagen fibrils) were calculated. The CFI, MAvD values were significantly lower in the wound samples. It is concluded that the biopsy technique may be a useful tool for research applications. The absence of exercise-induced effects on the collagen fibril population in the wound samples suggests that the first phase of the process of tendon healing in immature equine SDFT’s sustaining a minor surgically-induced wound, is not exercise-dependent. However, findings may be different in mature horses sustaining accidental trauma.A novel technique to take biopsies from immature equine flexor tendons was developed and used to evaluate the effect of various levels of exercise on the development of the collagen fibril diameter distribution in the resulting wounds. The technique appeared to be minimally invasive, but complication rate was deemed too high for clinical use. There was no effect of exercise on mass average diameter of collagen fibrils, suggesting that the repair process, at least in its initial stage, is exercise-independent.

Coll2-1 correlates well with the degenerative state of tarsocrural joints as evaluated by arthroscopy. This marker can therefore be classified as a burden-of-disease marker in the assessment of joint disease in horses.

Summary The fibre type composition of the deep gluteus muscle was studied in biopsies of Dutch Warmblood foals from birth until age 48 weeks. Half the foals were given box‐rest, the other half received exercise consisting of an increasing number of gallop sprints. The muscle fibre types were determined using monoclonal antibodies discriminating against the following myosin heavy chain (MHC) isoforms: types I, IIa, IId, Cardiac‐α and Developmental. During the first 48 weeks there was a consistent increase of fibres expressing types IIa MHC, replacing fibres expressing IId MHC. This change was reflected in the presence of a quite large population of fibres co‐expressing MHC IIa and IId. The difference between the exercised (training) and nonexercised (box‐rest) groups was small but suggested that the increase of type IIa fibres was larger in the training group. It appeared that after birth a significant number of fibres coexpress either Developmental and type IIa‐MHC or Cardiac‐α and type I‐MHC. The Developmental isoform disappears during the first 10 weeks after birth and almost all the α isoform expression during the first 22 weeks. It is concluded that a fast turnover of fibre types takes place in the deep gluteus medius in the first months postpartum. Potentially, exercise could have an effect on the rate of change of these fibre types.