laminitis

Radiological anatomy of the donkey's foot: Objective characterisation of the normal and laminitic donkey foot

Reason for study

Anatomical change within a laminitic foot is of diagnostic and prognostic importance. A lateromedial radiograph represents the current 'gold standard' by which these changes are identified. Detection of anatomical change is dependent upon a priori knowledge of normality and subjective assessment alone may not identify modest change. Normal baseline data is, therefore, needed against which objective comparisons can be made. There is little information regarding the radiological anatomy of the donkey foot, hence an equine model has been widely adopted. However, descriptive accounts suggest fundamental anatomical differences between these 2 species.

Objectives

To characterise objectively the radiological anatomy of normal donkey feet and define the nature and extent of anatomical change associated with laminitis.

Methods

The anatomy of the forefoot was quantified from lateromedial radiographs of 83 normal and 74 laminitic donkeys, using a computer based imaging system. Data were analysed using univariate and bivariate statistical methods.

Results

Baseline data were established that define the radiological characteristics of the anatomy of normal donkey feet. The key hoof, bone and weightbearing stance parameters of lateromedial radiographs have been evaluated. Laminitis was associated with significant rotation and distal displacement of the distal phalanx, increases in integument depth and morphometric change to the distal phalanx (P<0.05).

Conclusions

This study challenges the validity of applying an equine model to the radiological anatomy of donkey feet. Hence, the diagnosis of anatomical change cannot be based on baseline data previously given for the horse and guidelines should be revised accordingly for the donkey.

Potential relevance

This study provides an objective basis for the identification of anatomical change associated with laminitis in donkey feet.

Volume
43
Issue
4
Start page
478
End page
486
Publication date

Laminitis in donkeys: a pilot study investigating radiographic versus post-mortem measurements

Background

Laminitis is a painful disease of equines. Radiographic and post-mortem evaluations of feet are often an important part of welfare investigations, and professional opinions by veterinarians are necessary in resulting legal cases. Any difference in measurements between the two modalities can cause uncertainty, potentially affecting the legal decision.

Objectives

To quantify the difference between radiographic and postmortem pre-mortem vs. post-mortem effects.

Study design

Case series.

Methods

Seven donkeys with laminitis confirmed via standard workup, euthanased for reasons unrelated to the study, were selected. Weight-bearing and non-weight-bearing lateral radiographs were taken of both front feet within 24 h pre-mortem. Feet were removed and sagitally sectioned between 48 and 72 h post-mortem. Lateral radiographs were taken of the feet immediately following sectioning. Founder distance and rotation were evaluated at each time point and compared using paired t-tests (P < 0.05).

Results

Compared with pre-mortem weight-bearing radiographs, nonweight-bearing feet had a decreased founder distance and decreased rotation. Compared with pre-mortem non-weight- bearing radiographs, post-mortem feet had increased rotation and no change in founder distance. There were no significant differences between post-mortem direct measurements and post- mortem radiographs. Compared with standard weight-bearing radiographs, post-mortem measurements had a decreased founder distance and increased rotation.

Main limitations

Small sample size. Further samples are needed to confirm these initial conclusions.

Conclusions

Measurements of post-mortem feet have a decreased founder distance and an increased rotation compared with standard radiographic images. Changes in founder distance are seen due to changes in weight-bearing. Changes in rotation are seen post-mortem, and can be explained by autolysis of the laminae and/or rigor mortis causing tendon contracture. Most studies have focused on indications and severity of laminitis in living animals using radiographs: postmortem measurements should therefore be interpreted with caution.

Competing interests

None declared.

Ethical animal research

Approved by The Donkey Sanctuary. Donkeys were owned by The Donkey Sanctuary and were used with consent.

Sources of funding

The Donkey Sanctuary.

Volume
51
Issue
S53
Start page
10
End page
10
Publication date
Country

Hoof disorders and farriery in the donkey

This article provides a review of hoof anatomy and care in donkeys and mules. Hoof disease is a major cause of poor welfare and mortality globally. Problems associated with hoof disease are discussed in the context of behavior, diet, treatment, and prevention. The most common conditions encountered are discussed, including laminitis, the overgrown unbalanced hoof, white line disease, flexural deformities, and other significant issues. Differences between donkey and horse hoof anatomy are described.

Published online ahead of print.

Volume
35
Issue
3
Start page
643
End page
658
Publication date
Country

Donkey hoof disorders and their treatment

Disorders of the hoof have important health and welfare implications in donkeys. Clinical conditions that affect the donkey hoof include laminitis, which is one of the most common causes of lameness in donkeys in the UK, as well as white line disease/abscess, and chronic conditions such as overlong hooves. This article reviews the normal anatomy and function of the donkey’s foot, before discussing in more detail the diseases that can arise and their treatment.

Journal
Volume
35
Start page
135
End page
140
Publication date
Country

Development of a quantitative multivariable radiographic method to evaluate anatomic changes associated with laminitis in the forefeet of donkeys

Objective

To establish and validate an objective method of radiographic diagnosis of anatomic changes in laminitic forefeet of donkeys on the basis of data from a comprehensive series of radiographic measurements.

Animals

85 donkeys with and 85 without forelimb laminitis for baseline data determination; a cohort of 44 donkeys with and 18 without forelimb laminitis was used for validation analyses.

Procedures

For each donkey, lateromedial radiographic views of 1 weight-bearing forelimb were obtained; images from 11 laminitic and 2 nonlaminitic donkeys were excluded (motion artifact) from baseline data determination. Data from an a priori selection of 19 measurements of anatomic features of laminitic and nonlaminitic donkey feet were analyzed by use of a novel application of multivariate statistical techniques. The resultant diagnostic models were validated in a blinded manner with data from the separate cohort of laminitic and nonlaminitic donkeys.

Results

Data were modeled, and robust statistical rules were established for the diagnosis of anatomic changes within laminitic donkey forefeet. Component 1 scores ≤ −3.5 were indicative of extreme anatomic change, and scores from −2.0 to 0.0 denoted modest change. Nonlaminitic donkeys with a score from 0.5 to 1.0 should be considered as at risk for laminitis.

Conclusions and clinical relevance

Results indicated that the radiographic procedures evaluated can be used for the identification, assessment, and monitoring of anatomic changes associated with laminitis. Screening assessments by use of this method may enable early detection of mild anatomic change and identification of at-risk donkeys.

Volume
73
Issue
8
Start page
1207
End page
1218
Publication date
Country

EMS and PPID in donkeys

Alexandra K. Thiemann
Presentation date

Equine Metabolic Syndrome is defined as a “Clinical syndrome associated with an increased risk of laminitis that includes insulin dysregulation and any combination of increased generalised or regional adiposity, weight loss resistance, and altered adipokine concentrations.” https://sites.tufts.edu/edu/equineendogroup. Donkeys are prone to Equine Metabolic Syndrome due to their physiological adaptations to survive in resource poor environments. The donkey has a lower nutritional requirement than a pony of the same size, but is often exposed to excess feed with high non- structural carbohydrate levels. In addition, they are generally given little exercise.

Donkeys and many small pony breeds are considered to be relatively insulin resistant- which has a survival advantage, but also leads to, and is linked with both hyperinsulinemia and obesity.

As well as clinical symptoms we need to test for insulin dysregulation. Resting insulin levels have very low sensitivity /high specificity and should not be relied upon as a sole test. At The Donkey Sanctuary we use an oral carbohydrate challenge using Karol Light (corn syrup). As donkeys are at increased risk of hyperlipaemia we do not starve patients before testing, but have a standard protocol that involves the donkey only having access to straw for at least 6 hours prior to testing. We then give 45ml/100kg of syrup and obtain baseline blood samples. A second sample is taken 60-90 minutes later to measure serum insulin, which should be below 60mU/L.

At present adipokine testing is not validated for donkeys.

There will be cases of EMS that do not demonstrate obesity and cases that also suffer from concurrent PPID, so in some cases further diagnostics will be warranted. In many cases management of EMS relies on improving the dietary management of the donkey, and initiating a controlled weight loss programme. Ideally, the exercise is increased, but this will be dictated by whether there is any underlying lameness. To prevent boredom in cases of dietary restriction there are several ways to modify and enrich the stable environment.

Medical treatments exist: metformin can be used to reduce glucose absorption enterically and help in transitioning a donkey to pasture; a thyroxine derivative may be useful to increase the metabolic rate.

Pituitary Pars Intermedia Dysfunction (PPID) is seen in donkeys and, as many are kept until they are geriatric it is seen relatively frequently. The condition is known to be associated with an increased risk of immunosuppression and laminitis. Affected cases may have obvious clinical signs such as hirsutism, muscle wastage and polydipsia. However we rely upon testing suspect donkeys for elevations in ACTH to detect cases before such signs are reached.

PPID results in hyperinsulinemia, which is a risk factor for laminitis. We also find these cases may have higher faecal egg counts, higher ectoparasites burdens and delayed wound healing.

Treatment of the underlying disorder relied upon the use of pergolide- Prascend at 2µg/kg. As the drug can suppress appetite donkeys need careful monitoring when on the drug and may need to start at lower doses. Testing In autumn when the levels are at their highest is considered the best time to discriminate for positive cases.

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