Oxidative DNA damage in reconstituting T cells is associated with relapse and inferior survival after allo-SCT.

Allogeneic hematopoietic stem cell transplantation (allo-SCT) is the only curative treatment option for a number of hematologic malignancies. Its therapeutic potential relies on the potency of donor T cells to eliminate residual malignant cells, the so-called graft-versus-leukemia (GVL) effect. Disease relapse remains the most frequent treatment failure and is associated with poor outcome. Therefore, it is inevitable to decipher mechanisms that weaken GVL. In recent years, studies of tumor biology have revealed that metabolic remodeling of the micromilieu can critically regulate immune responses. Accumulation of reactive oxygen species leads to a metabolic condition known as oxidative stress, which can severely hamper T cells. Currently, only a few studies, mainly using preclinical models, have demonstrated the occurrence of oxidative stress after allo-SCTs. Therefore, we sought to investigate oxidative stress in a well-characterized group of patients who underwent allo-SCT and its impact on reconstituting T cells. We identified high concentrations of serum 8-hydroxydeoxyguanosine (8-OHdG) as an established biomarker for oxidative stress. 8-OHdG is one of the major products of DNA oxidation, which is normally rapidly removed. After allo-SCT, T cells accumulated oxidative DNA damage. High cellular 8-OHdG content (8-OHdGhi) was associated not only with signs of enhanced T-cell activation but also premature exhaustion. The inability of 8-OHdGhi T cells to efficiently target malignant cells or produce cytotoxic granzyme B and interferon gamma was associated with a significantly increased relapse risk and a shorter overall survival. Taken together, our novel findings could give reason to focus on bolstering DNA repair in reconstituting T cells as a means to improve GVL efficacy.

Agreement among equine veterinarians and between equine veterinarians and inertial sensor system during clinical examination of hindlimb lameness in horses.

BACKGROUND: Hindlimb lameness evaluation is known to be challenging. Experience is essential for the ability of equine veterinarians to detect lameness. Nevertheless, even an experienced veterinarian is still subject to bias. Objective lameness detecting methods have been established to aid veterinarians. OBJECTIVES: 1) To estimate the effect of experience on the interobserver agreement and the agreement between a body-mounted inertial sensor system (BMISS) and veterinarians on detecting hindlimb lameness, and 2) to estimate the agreement between the BMISS and highly experienced veterinarians on change in lameness after diagnostic analgesia. STUDY DESIGN: Cross-sectional study. METHODS: Twenty-six horses with hindlimb lameness were evaluated in clinical conditions by clinicians and simultaneously measured by the BMISS. Videos of their lameness examination were recorded and shown to 13 veterinarians from three groups of varying experience for evaluation. The interobserver agreement and the agreement between veterinarians and the BMISS were calculated. RESULTS: Interobserver agreement from all three groups was recorded as 'fair'. The strength of agreement between veterinarians and BMISS was 'fair' for the highly experienced group, 'slight to fair' for the moderately experienced group and 'slight' in the inexperienced group. The BMISS and the highly experienced veterinarians declared a 'strong' agreement in assigning an improvement in lameness after diagnostic analgesia. MAIN LIMITATIONS: Lameness evaluation through video viewing might be more challenging for some evaluators than live situations. CONCLUSIONS: Given the task of evaluating videos of horses trotting in a straight line, the more experienced veterinarians did not show more reliability than those with less experience. Due to 1) the moderate agreement between the BMISS and clinicians (highly experienced and moderately experienced) in the live clinical evaluation in determining hindlimb lameness, and 2) the strong association between the BMISS and highly experienced veterinarians in determining improvement of lameness after anaesthesia, therefore the use of the BMISS as a supporting tool for veterinarians is encouraged.

Radiological prevalence of equine odontoclastic tooth resorption and hypercementosis.

BACKGROUND: Equine odontoclastic tooth resorption and hypercementosis (EOTRH) is a painful and progressive dental disease that mainly affects the incisors and canine teeth of aged horses. Diagnosis is based on radiographs to detect early stages of the disease. EOTRH is probably underdiagnosed and its prevalence in Germany unknown. OBJECTIVE: This study was performed to determine the radiological prevalence of EOTRH in a large horse population in Berlin-Brandenburg, Germany. STUDY DESIGN: Prevalence study. METHODS: The study population (142 horses) consisted of all horses 10 years and older that were presented at the Equine Hospital for a routine dental examination. The horses were either presented as clinical cases (CC population) or belonged to a riding school (RS population). Digital radiographs of the incisor dentition were taken and evaluated for changes related to EOTRH, leading to an overall classification for each horse. RESULTS: The mean age of the study population was 21 years and ranged from 10 to 37 years. Overall, 94% of all horses had at least minor and 62% had moderate to severe radiological changes of the incisor teeth associated to EOTRH. No horse older than 14 years was without radiological signs of EOTRH and all horses over 28 years of age had at least moderate radiological changes of the incisor teeth. MAIN LIMITATIONS: The clinical cases group might have a bias towards horses with existing dental problems such as EOTRH, because they were presented explicitly for dental care to a clinic. CONCLUSION: Focusing on radiological changes, this study shows that EOTRH is a common condition of horses in Berlin-Brandenburg. With older age, disease is more frequent and radiological changes become more severe. Since no horse older than 14 years was without radiological findings, it is likely that mild changes may be associated with the normal tooth ageing process.

Effect of sedation on fore- and hindlimb lameness evaluation using body-mounted inertial sensors.

REASONS FOR PERFORMING STUDY: Diagnostic analgesia is an integral part of equine lameness examinations, but is challenging to perform in uncooperative horses. Using sedation to facilitate this might, because of analgesic and ataxia-inducing effects, interfere with lameness evaluation. OBJECTIVES: To evaluate whether sedation with low-dose xylazine would alter lameness amplitude as measured by body-mounted inertial sensors. STUDY DESIGN: Controlled experiment. METHODS: Forty-four horses were randomly split into 2 groups. Lameness was measured using body-mounted inertial sensors before and after injection of xylazine (0.3 mg/kg bwt) or saline. Sedation was measured at 5, 20 and 60 min following treatment, and lameness evaluations were performed before (Time 0) and at 20 and 60 min after treatment. Forelimb lameness was determined by measuring the vector sum of mean head height maximum and minimum differences between all right and left forelimb strides (n>25) collected with the horse trotting in a straight line. Hindlimb lameness amplitude was determined by measuring mean pelvic height maximum and minimum differences between right and left hindlimb strides. Numbers of horses staying the same, improving or worsening were compared between groups at each time interval. RESULTS: There were no significant differences in head or pelvic movement asymmetry between xylazine and saline treatment groups. However, a few horses with forelimb lameness in the xylazine treatment group showed a large decrease in head movement asymmetry (decrease in forelimb lameness) at 60 min following sedation. CONCLUSIONS: Low-dose sedation with xylazine may be used without the concern of potential lameness-masking effects for hindlimb lameness evaluation, but caution should be used in some horses with forelimb lameness of mild severity. The Summary is available in German - see Supporting information.

Comparison of healing in forelimb and hindlimb surgically induced core lesions of the equine superficial digital flexor tendon.

OBJECTIVE: Even though equine multi-limb tendinopathy models have been reported, it is unknown if fore- and hindlimb tendon healing behave similarly. The aim of this study was to compare the healing process of surgically induced superficial digital flexor tendon (SDFT) core lesions of fore- and hindlimbs in horses. METHODS: Tendon core lesions were surgically induced in the SDFT of both fore- and hindlimbs in eight horses. One randomly assigned forelimb and one randomly assigned hindlimb were injected with saline one and two weeks post-surgery. The healing process was monitored clinically and ultrasonographically. After 24 weeks, the tendons were harvested and biochemical, biomechanical and histological parameters were evaluated. RESULTS: Twenty-four weeks post-surgery, the forelimb SDFT lesions had a significantly higher colour Doppler ultrasound vascularization score (p = 0.02) and glycosaminoglycan concentration (p = 0.04) and a significantly lower hydroxylysylpyridinoline content (p = 0.03). CLINICAL RELEVANCE: Our results indicate that fore- and hindlimb SDFT surgically induced lesions exhibit significant differences in several important parameters of tendon healing 24 weeks post-surgery. These differences create significant challenges in using all four limbs and accurately interpreting the results that one might generate. Therefore these findings do not support the use of four-limb models for study of tendon injury until the reasons for these differences are much better understood.

The proximal aspect of the suspensory ligament in the horse: How precise are ultrasonographic measurements?

REASONS FOR PERFORMING STUDY: To evaluate intra- and interobserver variability in ultrasonographic measurements of the proximal aspect of the suspensory ligament (PSL) in the horse. HYPOTHESIS: A minimum difference of ≥20% is required to differentiate reliably between physiological and pathological alterations related to dimensions. MATERIALS AND METHODS: Two operators examined the PSL in all 4 limbs of 14 horses twice using different techniques and different probes with and without standoff pads. Measurements were taken from the longitudinal and transverse images. Inter- and intraoperator variability was evaluated using agreement indices (AI) and the 95% limits of agreement (LOA). RESULTS: On the longitudinal scan the mean inter- and intraoperator AIs for dorsopalmar/-plantar thickness were both ≥0.89 and the 95% LOA were within target values for almost all intra- and interoperator comparisons. Similar mean AIs and 95% LOA were calculated for the dorsopalmar/-plantar thickness on the transverse image. For lateromedial width, cross-sectional area and circumference on the transverse scan, the mean inter- and intraoperator AIs ranged between 0.81 and 0.95 and the 95% LOA were higher than target values regardless of the imaging technique used. In general, better values for AIs and 95% LOA were achieved in the fore- compared with the hindlimb. CONCLUSION AND CLINICAL RELEVANCE: Acceptable precision was identified within and between operators only for the dorsopalmar/-plantar thickness in longitudinal and in transverse scanning directions. For the lateromedial width, cross-sectional area and circumference, a relatively large variability was identified. This aspect has to be considered if these parameters are to be used for objective measurement of the PSL from the transverse ultrasound image.

An investigation of the relationship between race performance and superficial digital flexor tendonitis in the Thoroughbred racehorse.

REASONS FOR PERFORMING STUDY: There is limited information regarding the number of races and the period for evaluation of outcome which is critical for assessment of SDF tendonitis treatments. OBJECTIVE: To evaluate the re-injury rate and racing performance of Thoroughbred racehorses that sustain SDF tendonitis in relation to matched controls in terms of number of races post treatment and maximum racing performance ratings before and after injury. STUDY DESIGN: Clinical records and racing histories of 401 racehorses with a first occurrence of SDF tendonitis diagnosed by ultrasonography. Controls were of the same age, sex and were horses training in the same establishment at the time of injury as the case horses and where the trainer reported that the horse had not had a previous SDF tendon injury or treatment. RESULTS: Eighty percent of both case and control horses returned to racing after the date of injury, and the re-injury proportion within 3 years of treatment was 53%. The difference in Racing Post Rating((max)) (RPR((max))) and the Racing Post Rating in the race immediately before the treatment date was significantly smaller in case horses (mean = 9.6 lbs; range = 0-75) compared to control horses (mean = 17.0 lbs; range = 0-79). No significant decrease in RPR((max)) was noted post injury. No difference between case and control horses was found for return to racing and racing 3 times, but control horses were significantly more likely to compete 5 races post treatment date than case horses. CONCLUSION AND CLINICAL RELEVANCE: Injury was associated with an individual's pre-injury maximum performance level and return to racing and completion of 3 races are not useful indicator of the outcome of horses with SDF tendonitis. The assessment of the outcome of horses with an SDF injury in a population of racehorses using the number of races post injury requires a minimum of 5 races post injury to be a useful indicator. Further, a re-injury proportion in a population of horses in training for 3 years post treatment.

A pilot in vitro biomechanical comparison of locking compression plate fixation and kerf-cut cylinder fixation for ventral fusion of fourth and fifth equine cervical vertebrae.

INTRODUCTION: The mechanical properties of equine cervical vertebrae joined by implants have not yet been reported. Locking compression plates (LCP) may provide a useful alternative system to the commonly used stainless steel kerf-cut cylinders (KCC) currently used for fixation of cervical vertebrae in horses. OBJECTIVES: The objectives of this study were to establish a method for biomechanical testing of equine C4-C5 articulations and to compare the biomechanical properties of cadaveric spines stabilised with KCC and LCP. METHODS: Twenty-four equine cadaveric cervical spines were size measured from radiographs, and then randomly allocated to four groups. The C4-C5 articulation for each group was treated in the following way: group 1: KCC implanted, group 2: 8-hole 4.5/5.0 LCP implanted, group 3: 11-hole 3.5 LCP implanted and group 4: No implant. The specimens were fixed in resin and tested under four-point bending in ventral flexion until failure. Stiffness, maximum moment to failure and mode of failure were recorded for all specimens. General linear models were performed to analyse associations. RESULTS: All spines failed at the C4-C5 articulation. Failure however differed between groups with fractures in group 1, screw pull-out in groups 2 and 3, and disarticulation in group 4 being the common failure modes. The stiffness and maximum moment to failure of the KCC and LCP implanted spines were similar. Increasing age was significantly associated with decreasing moment to failure and increasing size was significantly associated with increasing moment to failure and stiffness. CLINICAL SIGNIFICANCE: This study describes a successful technique for examining the biomechanical properties of equine cervical vertebrae. The LCP constructs had similar mechanical properties to the KCC which may justify their use in clinical cases.

Surgical management of complete diaphyseal third metacarpal and metatarsal bone fractures: clinical outcome in 10 mature horses and 11 foals.

REASONS FOR PERFORMING STUDY: Osteosynthesis of third metacarpal (McIII) and third metatarsal (MtIII) bone fractures in horses is a surgical challenge and complications surrounding the repair are common. Retrospective studies evaluating surgical repair, complications and outcome are necessary to increase knowledge and improve success of long bone fracture repair in the horse. OBJECTIVES: To evaluate clinical findings, surgical repair, post operative complications and outcome of 10 mature horses and 11 foals with McIII or MtIII fractures that were treated with open reduction and internal fixation (ORIF). METHODS: Medical records were reviewed and follow-up information obtained by means of radiographs and/or telephone questionnaire. RESULTS: Survival was achieved in 62% of the horses (3 mature/10 foals). On long-term evaluation (> 6 months) 11 horses (2 mature/9 foals) were fit for their intended activity, one mature horse had a chronic low grade lameness, and one foal was lost to follow-up because it was sold. The main fracture types were simple transverse (333%) or simple oblique (28.6%) and 71.4% of the fractures were open, 3 Type I (one mature/2 foals) and 12 type II (7 mature/5 foals). The preoperative assessment revealed inadequate emergency treatment in 10 horses (5 mature/5 foals; 47.6%). Survival rate of horses with open fractures was 12.5% (1/8) in mature and 85.7% (6/7) in foals. Post operative incisional infection (4 mature, 3 foals) was only managed successfully in 2 foals. Fracture instability related to inadequate fracture fixation technique occurred in 4 horses (all mature) and was always associated with unsuccessful outcome. CONCLUSIONS: Age, bodyweight and infection are strongly associated with outcome in treatment of complete McIII/MtIII fractures. CLINICAL RELEVANCE: Rigid fixation using plates and screws can be successful in treatment of closed or open, complete diaphyseal McIII/MtIII fractures in mature horses and foals. Instable fixation, infection and a bodyweight > 320 kg are major risk factors for unsuccessful outcome.

Radiographic anatomy of the articular process joints of the caudal cervical vertebrae in the horse on lateral and oblique projections.

REASONS FOR PERFORMING STUDY: Plain radiography is the standard imaging technique for investigation of diseases associated with the articular process joints (APJ) of the caudal neck; however, the radiographic anatomy of these structures on both lateral and oblique radiographic projections has not previously been described in detail. OBJECTIVES: To determine the optimal technique for obtaining oblique radiographs of the APJ of the caudal cervical vertebrae (C4-5, C5-6 and C6-7) and to provide a detailed description of their normal radiographic appearance, on both lateral and oblique radiographic projections. METHODS: Radiopaque markers were used to highlight the contours of the APJ on both lateral and oblique radiographs. A novel cineradiographic technique was employed to determine the optimal oblique projection to permit both left and right APJ to be assessed on the same radiograph. Lateral and oblique radiographs of the caudal neck were obtained in 6 live horses under standing sedation to assess the feasibility of the technique. RESULTS: The radiopaque markers facilitated identification of the APJ by clearly outlining the margins of the cranial and caudal articular processes on lateral and oblique radiographs. The optimal range of angles for obtaining oblique radiographs was 50-55 degrees for C4-5, 45-55 degrees for C5-6 and 45-5 degrees for C6-7. Obtaining oblique radiographs within the specified range of angles resulted in a consistent radiographic image of the APJ in the caudal cervical region in the live individual. CONCLUSIONS AND POTENTIAL RELEVANCE: The description of the normal radiographic anatomy of the cervical APJ of the caudal neck region in horses provides a valuable reference for the interpretation of cervical radiographs. Using the standardised technique to obtain oblique radiographs of the equine cervical vertebrae may provide additional diagnostic information about the APJ.

The use of race winnings, ratings and a performance index to assess the effect of thermocautery of the soft palate for treatment of horses with suspected intermittent dorsal displacement. A case-control study in 110 racing Thoroughbreds.

REASONS FOR PERFORMING THE STUDY: There have been no reports of the efficacy of thermocautery of the soft palate (TSP) assessed objectively as a treatment of intermittent dorsal displacement of the soft palate (DDSP). OBJECTIVE: To compare: racing performance of horses that underwent thermocautery of the soft palate with matched controls; and 'Racing Post ratings' (RPR) with prize money won (RE) and a performance index (PI) for each of the horses in the study. HYPOTHESIS: Thermocautery of the soft palate has no beneficial effect on racing performance and the 3 measures of performance are significantly related. METHODS: The inclusion criteria were fulfilled by 110 horses and each was matched with 2 controls. Changes in performance were compared statistically. RPR, RE and PI were analysed using a regression model. RESULTS: The percentage of horses that improved in performance following the procedure was 28-51% for the 3 measures of performance, compared to 21-53% for the matched controls. There was no significant effect of the procedure on the changes in RPR or RE. There was a significant effect of the procedure on the change in PI (P=0.015) with more treated horses achieving an improved PI and fewer acquiring a worse PI than matched control horses. The measures of performance showed significant correlation. CONCLUSIONS: Thermocautery of the soft palate alone may not be the most efficacious treatment of DDSP. POTENTIAL RELEVANCE: Production of a reliable measure of racehorse performance may be possible.

Diagnostic accuracy of digital photography and image analysis for the measurement of foot conformation in the horse.

REASONS FOR PERFORMING STUDY: Rigorous evaluation of practicable methods for the objective assessment of foot conformation has not been performed. OBJECTIVES: To assess the practicability, precision and accuracy of the process of obtaining measurements of horses' feet using photography and image processing software. METHODS: Precision study: Lateral photographs of horses' feet were obtained twice by 2 veterinary surgeons (image acquisition - IAc). Photographs were analysed by 2 masked veterinary surgeons on 2 occasions (image analysis - IAn). Measurements were compared within and between operators for self and non-self acquired photographs. Agreement indices (AIs) and 95% limits of agreement (LOA) were calculated for the IAn process alone and for the combined IAc + IAn processes. Accuracy study: Measurements obtained from lateral photographs were compared with those obtained from lateromedial radiographs. AIs and 95% LOA were calculated for each measurement. RESULTS: Precision study: Mean intra- and interoperator AIs for the IAn process alone were > or = 0.90 while those for the combined IAc + IAn processes were > or = 0.89 for all measurements. Similar mean AIs and 95% LOA were calculated regardless of image origin. The 95% LOA for hoof angle, heel height/toe height% and coronary band angle for all comparisons were within target values. Accuracy study: Mean AIs were > or = 0.89 for all measurements. The 95% LOA for heel height/toe height% and coronary band angle were within target values. CONCLUSIONS: Excellent precision was identified within and between operators regardless of image origin. High levels of accuracy were also identified, especially for heel height/toe height% and coronary band angle, indicating that photography and radiography may be used interchangeably. POTENTIAL RELEVANCE: Acquisition and analysis of photographic images is an appropriate method for the objective measurement of foot conformation, both in clinical and, research settings.

Difference in the length of the medial and lateral metacarpal and metatarsal condyles in calves and cows--a post-mortem study.

Measurements were taken in the metacarpal and metatarsal bones in 42 calves and 10 dairy cows post-mortem to determine whether there are anatomical differences in bone length. Manual and digital measurements of various bone length parameters were taken. There was a significant difference in the mean length of the condyles of the metacarpal and the metatarsal bones in calves and cows, the lateral condyle being longer than the medial. In all but one metatarsal bone (98.8%), the lateral condyle was longer than the medial. In the metacarpal bones, the lateral condyle was longer in only 52.4% of the bones, in 21.2%, they had the same length and in 27.4% the medial condyle was longer. These intrinsic anatomical differences can help distinguish between the left and right metacarpal and metatarsal bones, for instance, in anatomical and archaeological studies. Knowledge of these differences might be useful for studies on digit function and on the possible predisposition of cattle to claw diseases in the lateral claws of the hind limbs.

Magnetic resonance imaging, ultrasonography and histology of the suspensory ligament origin: a comparative study of normal anatomy of warmblood horses.

REASONS FOR PERFORMING STUDY: The diagnosis of lameness caused by proximal metacarpal and metatarsal pain can be challenging. Magnetic resonance imaging (MRI) offers the possibility for further diagnosis but there have been no studies on the normal MRI appearance of the origin of the suspensory ligament (OSL) in conjunction with ultrasonography and histology. OBJECTIVES: To describe the MRI appearance of the OSL in fore- and hindlimbs of sound horses and compare it to the ultrasonographic and histological appearance. The findings can be used as reference values to recognise pathology in the OSL. METHODS: The OSL in the fore- and hindlimbs of 6 sound horses was examined by ultrasonography prior to death, and MRI and histology post mortem. Qualitative evaluation and morphometry of the OSL were performed and results of all modalities compared. RESULTS: Muscular tissue, artefacts, variable SL size and shape complicated ultrasonographic interpretation. In MRI and histology the forelimb OSL consisted of 2 portions, the lateral being significantly thicker than medial. The hindlimb SL had a single large area of origin. In fore- and hindlimbs, the amount of muscular tissue was significantly larger laterally than medially. Overall SL measurements using MRI were significantly higher than using histology and ultrasonography and histological higher than ultrasonographic measurements. Morphologically, there was a good correlation between MRI and histology. CONCLUSIONS: MRI provides more detailed information than ultrasonography regarding muscle fibre detection and OSL dimension and correlates morphologically well with histology. Therefore, ultrasonographic results should be regarded with caution. POTENTIAL RELEVANCE: MRI may be a diagnostic aid when other modalities fail to identify clearly the cause of proximal metacarpal and metatarsal pain; and may improve selection of adequate therapy and prognosis for injuries in this region.

Treatment of chronic proximal suspensory desmitis in horses using focused electrohydraulic shockwave therapy.

The objective of the present clinical report was to investigate the short- and long-term outcomes of chronic proximal suspensory desmitis (PSD) treated with Extracorporeal Shockwave Treatment (ESWT). Fifty-two horses with chronic PSD in the forelimb (34 cases) or hindlimb (22 cases) were included in the study. Three horses had lesions in both hindlimbs and one in both forelimbs. The origin of the suspensory ligament was treated every three weeks for a total of three treatments using 2000 impulses applied by a focused ESWT device (Equitron) at an energy flux density of 0.15 mJ/ mm2. This treatment regime was followed by box rest and a controlled exercise program of 12 weeks duration. The horses were assessed 3, 6, 12, 24 weeks and one year after the first treatment. Of the 34 cases with forelimb PSD, 21 (61.8%) had returned to full work by six months after diagnosis and 19 cases (55.9%) were still in full work one year after ESWT. Of the 22 horses with hindlimb PSD, 9 (40.9%) had returned to full work by six months and 4 (18.2%) were still in full work one year after diagnosis. There was no association (chi-square test) between the outcome and the severity of the initial ultrasonographic and/or radiographic findings. Compared with the results of other clinical studies, these findings suggest that in horses with PSD of fore- and hindlimb, the prognosis for returning to full work six months after diagnosis can be improved when ESWT and a controlled exercise program are used. However, a high rate of recurrence occurred in the hindlimb despite treatment.

[Do hoof cracks represent a superficial hoof-problem?]. / Sind die Hornspalten ein oberflächliches Hufproblem?

Fifty-four horses with hoof cracks were referred to the Equine Hospital of the University of Zurich, for treatment. The horses were admitted because of lameness or other symptoms caused by the cracks. Deep or complicated quarter cracks were the most common type of cracks diagnosed. Poor conformation and abnormal hoof shape were the most important causes of hoof crack development, whereas injury to the coronary band was a less frequently encountered cause. Effective treatment of this problem includes corrective shoeing, removing horn from the weight-bearing surface as well as from the crack with a Dremel tool and immobilization of the borders of the crack. However, even with such a therapy, the recurrence rate of hoof cracks was with 20% very high.