Caries in the infundibulum of the second upper premolar tooth in the horse

BACKGROUND: Swedish equine dental practices have empirically found that the prevalence of infundibular caries as a primary disorder in the first permanent premolar teeth (P2) of the horse upper jaw has increased during the last 10 years. A previously unknown bacterial species, Streptococcus devriesei (CCUG 47155(T)), which is related to Streptococcus mutans, has recently been isolated from these carious lesions. To understand the aetiology of caries in horses, it is essential to elucidate the relationship between S. devriesei and P2 infundibular caries. METHODS: The anterior infundibulum of maxillary P2, or the occlusal surface at the site of the infundibulum, in 117 horses and ponies, 77 with and 40 without caries in this tooth, was sampled for bacteriological analyses between 1990 and 2004. Samples were transported in VMGA III medium and then inoculated onto MSB agar. The approximate number of bacteria was counted in each sample and the isolates were characterised biochemically, using a commercial kit. RESULTS: All 50 samples taken from carious lesions after 2002 were positive for an S. mutans-like strain, i.e. S. devriesei. The bacteria were also found in four of the control animals, but were much less numerous than in samples from caries-affected horses. None of the swabs taken prior to 2002 were positive for this bacteria. CONCLUSION: Our results demonstrate that S. devriesei can colonise the infundibulum of P2 of the horse upper jaw, which can be fatal for the dental tissue. We conclude that S. devriesei is strongly associated with P2 caries in horses

A preliminary investigation of the subcutaneous tissue reaction to a 3D printed polydioxanone device in horses

BackgroundA 3D printed self-locking device made of polydioxanone (PDO) was developed to facilitate a standardized ligation technique. The subcutaneous tissue reaction to the device was evaluated after implantation in ten horses of mixed age, sex and breed and compared to loops of poly(lactic-co-glycolic acid) (PLGA). In two of the horses, the implants were removed before closing the skin. The appearance of the implants and surrounding tissue was followed over time using ultrasonography. Implants were removed after 10 and 27 (± 1) days for histologic examination.ResultsOn macroscopic inspection at day 10, the PDO-device was fragmented and the surrounding tissue was oedematous. On ultrasonographic examination, the device was seen as a hyperechoic structure with strong acoustic shadowing that could be detected 4 months post-implantation, but not at 7 months. Histology revealed a transient granulomatous inflammation, i.e., a foreign body reaction, which surrounded both PDO and PLGA implants. The type and intensity of the inflammation varied between individuals and tissue category.ConclusionsThe 3D printed PDO-device caused a transient inflammatory reaction in the subcutaneous tissue and complete resorption occurred between 4 and 7 months. Considering the intended use as a ligation device the early fragmentation warrants further adjustments of both material and the 3D printing process before the device can be used in a clinical setting

Ossification of ungular cartilages in front feet of cold-blooded trotters - a clinical radiographic evaluation of development over time

BACKGROUND: It has not yet been shown that ossification of ungular cartilages (OUC) is a pathological condition. Beside heredity, factors such as sex, age, repeated concussion, local trauma, hoof and body size have been suggested as contributing factors for OUC development. By comparing radiographs of front hooves from cold-blooded trotters with different age we wanted to evaluate when development of OUC in cold-blooded trotters occurs and if and when it stabilizes in relation to age and workload. Diagnosis and grading of OUC were based on radiological field examinations of 649 Swedish and Norwegian cold-blooded trotters’ front hooves. A hundred and forty-seven of the horses were re-examined 3-13 years (mean age 9, median 8 years) after the first occasion. All radiographs were evaluated blind, using two different grading systems for OUC. Work load, in form of number of races completed, and body size score were collected from official data. Four statistical ordinal regression models were used, compared and evaluated. RESULTS: We identified a breakpoint at 2.8 ± 0.38 years of age when ossification ends and proposed a simpler grading system with more consistent results. There was no significant correlation between body size and grade of OUC. Comparison of different statistical methods for evaluation of ordinal data revealed a piecewise linear regression model as most suitable. CONCLUSIONS: Individuals with OUC developed this condition during the stage of life when their hooves develop in size. Results from this study can assist equine practitioners when examining and for understanding this condition in their clinical work and is also beneficial for the Scandinavian equine industry when devising breeding programs

Studies on the cytokeratins of the equine hoof wall, chestnut and skin, with special reference to laminitis

Inhibited differentiation Of the hoof keratinocytes has been proposed as a mechanism underlying the epidermal histopathology of equine laminitis. The aim of this thesis was to carry out morphological studies on the keratinocytes and immunohistochemical and biochemical studies on the cytokeratins of the equine hoof wall and chestnut in order to elucidate the differentiation ofthese cells in an acute attack ofspontaneous laminitis. The investigation comprised four studies. Study I was a histopathological analysis of the hoof wall, skin and chestnut in horses with spontaneous laminitis in the acute phase, i.e. within 48 hours of onset of lameness, and in horses with no symptoms of laminitis, with special emphasis on the epidermal basal cells. In studies II-IV, in the same groups of horses, an analysis was made of the cytokeratin composition of the corresponding tissues and of the cytokeratin distribution in these tissues with the aid of one- and twodimensional electrophoresis and immunohistochemistry, respectively.In horses with acute laminitis, inhibited differentiation of keratinocytes in the zone of cornification of the hoof wall and chestnut was observed morphologically. Further, there was an increased rate ofproliferation in the stratum internum ofthe hoofwall as well as in the strata medium and externum and to some extent also in the chestnut. Moreover, in those horses with laminitis with inhibited differentiation of keratinocytes in the zone of cornification of the hoof wall and chestnut, the basal cell layer was affected at the same time. The bio- and immunohistochemical studies in horses with laminitis showed that the types of cytokeratins present in the hoof wall and chestnut were identical to those in normal horses, but there was a change regarding the cell layers in which they were expressed.Taken together, the increased rate of proliferation among epidermal cells, the change regarding the cell layers in which cytokeratins were expressed, the less differentiated appearance of the suprabasal cells and the probably primary changes in the zone of cornification that were observed early in acute spontaneous laminitis indicate that primary inhibition of differentiation ofthe hoof keratinocytes occurs in laminitis.The observed change in the tissue distribution of cytokeratins was most likely caused by an increased proliferation among the epidermal cells. No “new” types of cytokeratins were produced in the tissues examined; hence it appears natural to consider the role of the cysteine-rich keratin-associated proteins in acute laminitis, and this issue is discussed in the present thesis

In Vivo Versus In Vitro Degradation of a 3D Printed Resorbable Device for Ligation of Vascular Tissue in Horses

A resorbable 3D printed polydioxanone (PDO) device is manufactured to facilitate ligation of vascular tissue during surgery. The device must provide sufficient mechanical performance throughout the healing period. Therefore, degradation and mechanical performance of the device are investigated as a function of in vivo and in vitro aging. During aging the PDO device released cyclic and linear water-soluble products. In vivo aging resulted in higher relative number of linear oligomers in comparison to in vitro aging. A major loss of mechanical performance is observed after only 10 days in vivo and the Young's modulus (E) and tensile strength at break (sigma(b)) decreased by 28% and 54%, respectively. This is in contrast to in vitro aging, where no loss of mechanical properties is observed during the same period. The in vivo aged devices exhibit clear holes in the matrices after 28 days, while apparent cracks are observed first after 140 days in vitro. These results highlight the sensitivity of the degradation process of resorbable devices with regards to the interactions of the device with the surrounding environment (tissues) and demonstrate the importance of in vivo testing as compliment to in vitro testing before clinical use of devices