Radiographic and radiological assessment of laminitis

Radiological measurements of the feet of normal Straight Egyptian Arabian horses in Qatar

The Arabian horse has been identified as carrying a risk locus for equine metabolic syndrome, predisposing this breed to development of laminitis. Radigraphy of the equine foot is widely considered the main diagnostic imaging technique for evaluation of the laminitic horse. Knowledge of 'normal' breed values allows assessment of the degree and severity of radiological changes associated with laminitis. The objective of this study was to investigate the normal values for radiological measurements of the feet of the Straight Egyptian Arabian horse in Qatar. The design was a clinical prospective study. Radiographs of the fore and hind feet of 10 clinically normal adult Straight Egyptian Arabian horses were taken. On the lateromedial views, 17 measurements were taken (13 distances and four angles). On the horizontal dorsopalmar/plantar views, two measurements were taken. On the dorsal 45 degree, proximo-palmarodistal oblique projections, four measurements were taken. Normal reference ranges were reported for radiological measurements of the feet of the Straight Egyptian Arabian horse. Several variables showed significant differences between fore and hind feet, including hoof angle, distal wall thickness, and two proximal inner layer measurements (p < 0.05). In addition, the Straight Egyptian Arabian horse was found to have a number of measurements which varied from previously published reports. The results reported within provide a useful reference for normal radiographic measurements of the Straight Egyptian Arabian horse with relevance for laminitis.

The Detection of Thoracolumbar Spine Injuries in Horses with Chronic Laminitis Using a Novel Clinical-Assessment Protocol and Ultrasonographic Examination

Postural adaptation is a prominent feature in horses affected by laminitis. Laminitis induces intense pain, especially in the forelimbs, prompting affected horses to assume a caudally displaced trunk posture, resulting in the hyperflexion of the thoracolumbar spine. This study assessed the nature and prevalence of thoracolumbar injuries in horses with chronic laminitis compared to horses without it. Sixty horses were used (thirty laminitic and thirty non-laminitic) of different athletic purposes and ages (2-20 years). The experimental protocol entailed a single assessment of horses' thoracolumbar spines, utilizing physical examination by MACCTORE, a scoring system developed specifically for this study. Additional evaluations included the Grimace Equine Pain Scale (HGS) and ultrasound exams. Statistical tests were used to compare values (Mann-Whitney or t-test) and lesions prevalences (Fisher) between groups (p < 0.05). The results showed a higher pain manifestation (HGS and heart rate, p < 0.0001) and thoracolumbar-spine-injury levels in chronic laminitis horses, both in MACCTORE clinical examinations (11.7 ± 4.8 vs. 4.2 ± 3.3, p < 0.0001) and general ultrasonographic indices (39.6 ± 12.0 vs. 20.7 ± 7.1, p < 0.0001), including specific examination approaches for various spinal elements. Horses with laminitis presented with a 14-fold higher prevalence of ultrasound-relevant lesions in the thoracolumbar spine (CI: 4.4 to 50.6, p < 0.0001) compared to controls. These findings constitute new evidence of an association between chronic laminitis and the presence of thoracolumbar spine injuries in horses, which may be confirmed by more sophisticated study designs.

The influence of equine hoof conformation on the initiation and progression of laminitis

BACKGROUND

The health and performance of horses are significantly affected by diseases associated with the hoof. Laminitis is a critical hoof disease that causes pain and, potentially, severe hoof and bone pathology.

OBJECTIVE

To generate an equine hoof finite element (FE) model to investigate the impact of normal and toe-in hoof conformations on the degeneration (decrease in elastic modulus) of the laminar junction (LJ), as occurs in chronic laminitis.

STUDY DESIGN

Computer software modelling.

METHODS

A hoof FE model was generated to investigate the biomechanics of hoof laminitis. A 3D model, consisting of nine components, was constructed from computed tomography scans of an equine left forelimb hoof. The model was loaded with 100 cycles of trotting. Two different centres of pressure (COP) paths representing normal and toe-in conformations were assigned to the model. LJ injury was modelled by degenerating the tissue's elastic modulus in the presence of excessive maximum principal stresses.

RESULTS

FE models successfully showed findings similar to clinical observations, confirming third phalanx (P3) dorsal rotation, a symmetric distal displacement of the P3 (2 mm at the lateral and medial sides) in the normal model, and an asymmetric distal displacement of the P3 (4 mm at the lateral and 1.5 mm at the medial side) in the toe-in model. The proximal distance between P3 and the ground after LJ degeneration in the current model was significantly different from experimental measurements from healthy hooves (P < 0.01).

MAIN LIMITATIONS

The inability to account for variations in population geometry and approximation of boundary conditions and system relations were the limitations of the current study.

CONCLUSIONS

The distribution of LJ tissue degeneration was symmetric at the quarters in the normal hoof and in comparison, there was a lateral concentration of degeneration in the toe-in model.

Transmural Ultrasonography in the Evaluation of Horse Hoof Internal Structures: Comparative Quantitative Findings-Part 2

The transmural ultrasound allows for the definition of the normal appearance of the hoof tissues and internal structures. Determining such measurements and proportions could contribute to evaluations of the normal spatial distal phalanx-hoof relationship. The objective was to describe the hoof's dermis and epidermis measurements using the transmural technique, in comparison with DR and anatomical sections. Sixty-two healthy hooves without digital radiographic abnormalities, made up of 30 anatomical pieces (phase 1) and 32 alive horse hooves (phase 2), and 16 sagittal sections of the first ones were used. The proximal and distal planes were compared, defining the following measurements: coronary band-extensor process, distal phalanx apex-hoof wall, sole dermis, middle stratum, parietal dermis, lamellar layer, the sublamellar dermis, and ratios between them. Most of the measurements were consistent among methods. Some showed measurement differences and a minority was impossible to determine. The transmural technique allowed for the observation and replication of measurements of the hoof structures, described with other diagnostic aids. It also allowed for the implementation of new measurements that would help to determine the spatial location of the distal phalanx. Additionally, it contributes to the visualization of normal findings, which will be useful to compare variations in the different phases of laminitis.

An Estimation of Lameness in Sable Island Horses Using Radiographic Evaluation of the Distal Phalanx and Hoof Capsule

Laminitis is a painful condition that causes lameness in horses. However, monitoring this condition in feral horses is logistically difficult. Laminitis can be detected postmortem, as inflammation of the sensitive laminae of the hoof changes the relative location of the bony structures within the hoof capsule. Thus, evaluation of cadavers may be used to estimate laminitis prevalence in feral populations of horses. The objective of this study was to estimate the prevalence of laminitis in feral horses inhabiting the Sable Island National Park Reserve, Canada, using radiographic imagery on the hooves of naturally deceased horses. Radiographic indicators evaluated included coronary band extensor process distance (CE), capsular rotation (CR), palmar angle (PA), ratio of the dorsal hoof wall thickness to the length of the distal phalanx (DHWT:P3) and sole depth (SLD). Each value measured indicated the following prevalence of laminitis: CE 0% (97.5% Confidence Interval (CI) 0-4.51%), 8.75% CR (95%CI 3.59-17.2%), PA 25% (95% CI 15.99-35.94%), DHWT:P3 6.25% (95%CI 2.06-14.0%) and 65% SLD (95% CI 53.52-75.33%). The majority of indices measured for laminitis were low. These findings suggest that laminitis is fairly infrequent in the Sable Island horses evaluated in this study.

Comparison of Six Different Methods for Measuring the Equine Hoof and Recording of its Three-Dimensional Conformation

Different measuring techniques have been used to objectify the classification of hoof shape. The MicroScribe is a novel tool that might prove useful for measuring hooves without prior reconstruction or compensation of projection artefacts. The aim of this study was to compare biometric data of the equine hoof collected by the MicroScribe tool and measurements collected directly from hooves, scaled photographs and radiographs, from photogrammetry models and computed tomography datasets. The suitability of MicroScribe generated data to differentiate individual hoof conformations was tested. A total of 62 measures were recorded from 16 forehooves. 21 linear and nine angular measures were collected by at least four methods each, and evaluated further by analysis of variance (ANOVA) and multivariate analysis of variance (MANOVA). Ratios and differences of these measures were calculated as suitable for the definition of hoof shapes and analysed as well. Absolute equivalency of methods was detected for five linear and none of the angular measurements. The precision of the tested measurement methods was comparable. In some cases, different methods measure different structures. Radiographs tended to overestimate, while computed tomography slides to underestimate distances. Photogrammetry and scaled photographs were less suitable for measuring hoof angles. The MicroScribe tool can readily be used for hoof measurements. Its values for linear measures showed good equivalency with other methods based on real hooves. For angular measurements, the uneven hoof surface might introduce imprecision. Not all hoof conformations could be detected based on measuring results alone. Diagnosis by a skilled veterinarian is still essential.

Shoe configuration effects on third phalanx and capsule motion of unaffected and laminitic equine hooves in-situ

Equine shoes provide hoof protection and support weakened or damaged hoof tissues. Two hypotheses were tested in this study: 1) motion of the third phalanx (P3) and hoof wall deformation are greater in laminitic versus unaffected hooves regardless of shoe type; 2) P3 displacement and hoof wall deformation are greatest while unshod (US), less with open-heel (OH), then egg-bar (EB) shoes, and least with heart-bar (HB) shoes for both hoof conditions. Distal forelimbs (8/condition) were subjected to compressive forces (1.0x102-5.5x103 N) while a real-time motion detection system recorded markers on P3 and the hoof wall coronary band, vertical midpoint, and solar margin. Magnitude and direction of P3 displacement and changes in proximal and distal hemi-circumference, quarter and heel height and proximal and distal heel width were quantified. Hoof condition and shoe effects were assessed with 2-way ANOVA (p<0.05). P3 displacement was greater in laminitic hooves when US or with OH, and EB and HB reduced P3 displacement in laminitic hooves. P3 displacement was similar among shoes in unaffected hooves and greatest in laminitic hooves with OH, then US, EB and HB. EB and HB increased P3 displacement from the dorsal wall in unaffected hooves and decreased it in laminitic hooves. OH and EB increased P3 motion from the coronary band in laminitic hooves, and HB decreased P3 motion toward the solar margin in unaffected and laminitic hooves. In laminitic hooves, HB reduced distal hemi-circumference and quarter deformation and increased heel deformation and expansion. Proximal hemi-circumference constriction was inversely related to proximal heel expansion with and without shoes. Overall, shoe configuration alters hoof deformation distinctly between unaffected and laminitic hooves, and HB provided the greatest P3 stability in laminitic hooves. These unique results about P3 motion and hoof deformation in laminitic and unaffected hooves inform shoe selection and design.

Foot shape and radiographs of free-ranging Nubian giraffe in Uganda

Foot health in zoo giraffe has been a topic of recent research, although little is known about the foot health of free-ranging giraffe. This study describes the foot shape and radiographic pathological changes in 27 young adult Nubian giraffe (Giraffa camelopardalis camelopardalis) from a translocation in Uganda (August 2017). Giraffe feet were observed to have a concave sole, the hoof wall was longest by the toe tip, and the weight-bearing surface of the foot was primarily along the periphery of the foot including hoof wall, parts of the heel, and the edge of the sole. Radiographs showed that pedal osteitis and sesamoid bone cysts were relatively uncommon (3/24 giraffe with osteitis, 1/24 giraffe with sesamoid cysts), and that no giraffe in the study had P3 joint osteoarthritis, P3 rotation, or P3 fractures. Radiographs consistently demonstrated a positive palmar/plantar angle with the sole of the hoof thicker at the heel than by the toe tip, with the non weight-bearing palmar/plantar angle measuring 1.6°- 4.3°. This is the first systematic review of foot shape and radiographs in free-ranging giraffe and demonstrates a low prevalence of foot pathologies. This study suggests qualitative differences in foot shape, foot health, radiographic anatomy, and foot pathologies when comparing free-ranging and zoo giraffe. Further research is needed to identify why these differences occur and whether husbandry modifications could help improve zoo giraffe foot health and prevent associated lameness.

Endocrinopathic Laminitis

Endocrinopathic laminitis (EL) primarily occurs because of insulin dysregulation (ID) mediated through downstream effects of insulin on IGF-1R in lamellar tissues. There is likely contributing vascular and metabolic dysfunction within the lamellae, but EL is relatively non-inflammatory. EL is associated with lamellar stretching, proliferation, and failure, ultimately causing failure of the suspensory apparatus of the distal phalanx. Proper education regarding mitigating risk factors makes this a largely preventable cause of laminitis. Annual hoof evaluation plus screening geriatric horses for pituitary pars intermedia dysfunction and ID, and younger horses for ID, can significantly decrease the incidence of this devastating condition.

Effect of heel elevation on breakover phase in horses with laminitis

Background

In a laminitic horse, the maximal loading of the toe region occurs during the breakover phase. To date, no kinetic data demonstrates the effect of supportive orthopaedic therapy in horses with laminitis on breakover phase. Thus, the purpose of this study was to examine the effect of heel elevation on the breakover phase. Eight horses with acute laminitis treated medically as well as with application of a hoof cast with heel wedge (HCHW) were included in this study. Immediately following cessation of clinical signs of acute laminitis, two measurements using the Hoof™ System were taken: the first with HCHW and the second immediately following removal of the HCHW, i.e. in barefoot condition (BFC). The hoof print was divided into three regions: toe, middle hoof, and heel. Kinetic parameters included vertical force (VF), stance duration, contact area (CA) for all hoof regions during stance phase, duration of breakover, VF in the toe region at onset of breakover and location of centre of force.

Results

The VF and CA were higher in the heel region (63 and 61%, respectively) and decreased significantly after removal of the HCHW (43 and 28% after removal, respectively). The breakover phase in horses with HCHW lasted 2% of stance phase and was significantly shorter than that in BFC, which lasted 6% of stance phase. The VF at onset of breakover for the toe region in horses with HCHW was significantly lower than that in BFC. The centre of the force was located at the heel region in all horses with the HCHW, and at the middle the hoof region in BFC.

Conclusions

Heel elevation in horses with laminitis as examined on a concrete surface significantly shortens breakover phase and decreases the vertical force in the toe region during breakover. HCHW provides adequate support to the palmar hoof structures by increasing the contact area in the heel region and incorporating the palmar part of frog and sole into weight bearing, thus decreasing the stress on the lamellae. Hoof cast with heel elevation could be a beneficial orthopaedic supportive therapy for horses suffering from acute laminitis.

Hoof kinetic patterns differ between sound and laminitic horses

BACKGROUND

No kinetic data on hoof loading in laminitic horses are available, despite their importance for optimising supportive shoeing therapies.

OBJECTIVES

To quantify the load distribution pattern in laminitic and sound horses.

STUDY DESIGN

Controlled observational study.

METHODS

Fifty-four sound and laminitic horses were assigned to three groups: control group (sound horses), group 1 (G1) horses with acute laminitis, evaluated immediately after acute clinical signs subsided, and group 2 (G2) horses that had been free of acute laminitis signs for 6-12 weeks. Measurements on both forelimbs in barefoot condition were performed during walk using the Hoof^™ System. Kinetic parameters were recorded and compared between hoof regions and groups using covariance analyses and t tests (P < .05).

RESULTS

Peak loading in the toe region occurred during midstance phase in control group, but during break-over in laminitic horses. This is reflected by the time to peak vertical force in the toe, which was significantly shorter in the control group compared to laminitic horses (G1 and G2) (76% ± 6% vs 89% ± 9 [P = .002], 86% ± 7 [P = .001] of stance duration respectively). The relative vertical force in the toe in the control group (46% ± 7%) was significantly higher compared to laminitic horses (G1: 29% ± 9% [P = .001]; G2: 32% ± 10% [P = .003]). The main shift of the load occurred between toe and middle hoof regions in laminitic horses as compared with the control group. No significant differences were found between G1 and G2.

MAIN LIMITATIONS

Measurements were not obtained in horses with acute laminitis on admission, to avoid risk of further damage to the lamellae.

CONCLUSIONS

Supportive therapy in laminitis should focus on supporting both caudal and middle hoof areas to decrease the peak pressure in these regions, and ease break-over during which the maximal loading of the toe occurs.

Novel technique for prevention of rotation of the distal phalanx relative to the hoof wall in horses with acute laminitis

OBJECTIVE

To determine the holding capacity of a 5.5-mm-diameter cortical bone screw when placed in the third phalanx (P3) of horses and assess whether screw placement through the dorsal hoof wall into P3 would be tolerated by clinically normal horses and would alleviate signs of pain and prevent P3 rotation in horses with oligofructose-induced laminitis.

ANIMALS

40 limbs from 10 equine cadavers and 19 clinically normal adult horses.

PROCEDURES

In part 1 of a 3-part study, a 5.5-mm-diameter cortical bone screw was inserted by use of a lag-screw technique through the dorsal hoof wall midline into P3 of 40 cadaveric limbs and tested to failure to determine screw pullout force. In part 2, 6 horses had 5.5-mm-diameter cortical bone screws placed in both forefeet as described for part 1. Screws were removed 4 days after placement. Horses were monitored for lameness before and for 2 weeks after screw removal. In part 3, 13 horses were randomly assigned to serve as controls (n = 3) or undergo screw placement without (group 2; 6) or with (group 3; 4) a washer. Following the acquisition of baseline data, horses were sedated and administered oligofructose (10 g/kg) via a stomach tube. Twenty-four hours later, screws were placed as previously described in both forefeet of horses in groups 2 and 3. Horses were assessed every 4 hours, and radiographic images of the feet were obtained at 96 and 120 hours after oligofructose administration. Horses were euthanized, and the feet were harvested for histologic examination.

RESULTS

The mean ± SD screw pullout force was 3,908.7 ± 1,473.4 N, and it was positively affected by the depth of screw insertion into P3. Horses of part 2 tolerated screw placement and removal well and did not become lame. All horses of part 3 developed signs of acute lameness, and the distance between P3 and the dorsal hoof wall increased slightly over time. The change in the ratio of the dorsal hoof wall width at the extensor process of P3 to that at the tip of P3 over time was the only variable significantly associated with treatment.

CONCLUSIONS AND CLINICAL RELEVANCE

Placement of a 5.5-mm-diameter cortical bone screw through the dorsal hoof wall into P3 had sufficient holding power to counteract the pull of the deep digital flexor tendon in approximately 500-kg horses, and placement of such a screw was well tolerated by clinically normal horses but did not alleviate signs of pain in horses with oligofructose-induced laminitis. Further research is necessary before this technique can be recommended for horses with naturally occurring acute laminitis.

Relação espacial entre o estojo córneo e a falange distal em éguas Campolina adultas com e sem obesidade

RESUMO A laminite endocrinopática tem acometido um número crescente de equinos com sinais de obesidade. Em um estudo recente com fêmeas jovens (até cinco anos) da raça Campolina, demonstraram-se indícios de alterações no dígito, ainda discretas, aparentemente associadas ao aumento da adiposidade. Com a hipótese de que essa associação é mais evidente em animais em faixa etária superior, o objetivo do presente estudo foi estudar éguas adultas (acima de cinco anos) da raça Campolina com e sem obesidade, avaliando-se radiograficamente a relação espacial entre estojo córneo e falange distal. Foram utilizadas 27 éguas entre seis e 14 anos de idade, sendo analisadas variáveis de adiposidade e medidas radiográficas dos cascos dos membros torácicos de equinos com escore corporal de 5 a 7/9 (grupo controle) e de 8 a 9 (grupo obeso). Foram feitas comparações entre os grupos e correlacionaram-se as variáveis de adiposidade com variáveis casco. A distância de afundamento da falange distal foi cerca de 20% superior nas éguas obesas (12,3±2,5 contra 10,2±2,2mm no grupo controle). Esse parâmetro também correlacionou (P<0,01) com vários parâmetros de adiposidade, com destaque para o escore de condição corporal (r=0,47) e a circunferência de pescoço a 75% (r=0,42). Os resultados corroboram estudos prévios que demonstraram associação entre obesidade e indícios de separação entre falange distal e estojo córneo em equinos de raças nacionais, comprovando, assim, a utilidade da avaliação radiográfica nesses animais. Em conclusão, éguas da raça Campolina com obesidade possuem alterações evidentes na relação espacial entre estojo córneo e falange distal, que se intensificam com o aumento da idade e da adiposidade.

Phenotypic, hormonal, and clinical characteristics of equine endocrinopathic laminitis

Background

Equine endocrinopathic laminitis is common and can be associated with an underlying endocrinopathy, such as equine metabolic syndrome (EMS), pituitary pars intermedia dysfunction (PPID), pasture consumption, or any combination of these factors.

Objectives

The aim of the study was to improve the risk assessment capabilities of clinicians, and to inform management strategies, for acute endocrinopathic laminitis by prospectively examining the phenotypic, hormonal, and clinical characteristics of the disease in a large cohort.

Animals

Privately owned horses and ponies (n = 301) of any age, sex, or breed diagnosed with laminitis by a veterinarian. A history of laminitis was acceptable.

Methods

This was a prospective cohort study. Veterinarians provided information on each case via an online questionnaire after informed consent from the animal's owner, and all data were de‐identified before analysis. Serum insulin and plasma adrenocorticotrophic hormone concentrations were measured in each case.

Results

Most cases were recruited in spring (109/301; 36.2%). Concurrent EMS and PPID resulted in higher basal insulin concentrations (49 [21.5‐141]; P < .02) than if an animal had a single underlying cause for their laminitis. The insulin concentration was negatively correlated (r² = −0.38; P < .001) with the animal's height, being higher in ponies (33[10‐14]; P < .001) than horses (9.5 [3‐25.7]) and was positively correlated (r² = 0.12; P = .05) with their grade (severity) of laminitis.

Conclusions and Clinical Importance

Horses and ponies with concurrent endocrinopathies have more marked hyperinsulinemia. Higher basal insulin concentrations were associated with more severe lameness.

RADIOGRAPHIC AND ANATOMIC CHARACTERISTICS OF DORSAL HOOF WALL LAYERS IN NONLAMINITIC HORSES

Early radiographic diagnosis of acute laminitis is important for treatment planning and prognosis in horses. While four histopathologic layers make up the hoof wall, only two layers are distinguished on digital radiographs of horses' hooves. Objectives of this descriptive study were to determine which macroscopic layers correspond to the two radiographically visible layers, and to describe radiographic layer measurements in a group of clinically sound Warmblood horses. Twelve ex vivo equine hooves were examined at three different levels of the dorsal hoof wall. The four macroscopic layers were variably grouped and compared with radiographic layers. Stratum externum and stratum medium represented the superficial radiographic layer while stratum internum and dermis parietis represented the deep layer. In 27 clinically sound horses (54 thoracic feet), the superficial radiographic layer represented 64.3% ± 3.6% of the total dorsal hoof wall. Findings from this study provided baseline information for future studies of horses with acute laminitis.