The structure, innervation and location of arteriovenous anastomoses in the equine foot.
Abstract: In the foot of the horse, arteriovenous anastomoses (AVAs) of epithelioid type occurred in the dermis of the coronary band, in the coronary and terminal papillae, in neurovascular bundles and at the entrance to and along the length of the dermal laminae. A particular feature of the epithelioid segment of AVAs in the horse, compared with that of other species, was the height and surface complexity of many of the endothelial cells. They extended into the lumen, forming undercut and tunnel-like areas which correlated with the characteristic surface marking of AVAs observed in vascular casts. The number of cell organelles, including the concentration of vesicles in the luminal cytoplasm, suggested cells with a high metabolic activity. The luminal surface possessed numerous microvilli and long cytoplasmic cell processes which appeared to surround material in the lumen. The innervation of AVAs was more dense than that of the arteries and consisted of adrenergic and peptidergic nerves. Noradrenaline- and neuropeptide Y-containing nerves were identified as the vasoconstrictor components of the nerve supply and occurred along arteries and formed dense plexuses around AVAs. Calcitonin gene-related peptide, substance P and vasoactive intestinal polypeptide are vasodilators and were present in single nerve fibres which accompanied arteries and AVAs along the length of the dermal laminae. In this study the distribution, density and innervation of AVAs in the equine foot are correlated with their proposed role in the development of acute laminitis. The release of vasoactive peptides from diseased organs remote from the foot may induce inappropriate prolonged dilatation of AVAs and thus contribute to the laminar ischaemia of acute laminitis.
Publication Date: 1994-07-01 PubMed ID: 8575398DOI: 10.1111/j.2042-3306.1994.tb04391.xGoogle Scholar: Lookup
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- Journal Article
- Research Support
- Non-U.S. Gov't
Summary
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The research article discusses the anatomical structure, nerve supply, and location of arteriovenous anastomoses (AVAs) in the horse’s foot and how these aspects relate to acute laminitis, a common disease in horses characterized by severe foot pain.
Structure and Location of Arteriovenous Anastomoses
- The study found that AVAs, specifically of the epithelioid type, are located in several areas of the horse’s foot, including the dermis of the coronary band, coronary and terminal papillae, neurovascular bundles, and along the dermal laminae.
- Unique to horses, compared with other species, is the intricate structure of the endothelial cells in the epithelioid segment of AVAs. These cells have a complex surface and extend into the lumen, forming areas that resemble undercuts and tunnels.
- This unique structure correlates with the characteristic surface marking of AVAs observed in vascular casts.
Metabolic Activity of AVAs
- The high number of cell organelles, especially vesicles in the luminal cytoplasm, suggests the endothelial cells in AVAs are highly metabolically active.
- The luminal surface also has numerous microvilli and extended cytoplasmic processes that seem to surround material within the lumen.
Innervation of AVAs
- AVAs are densely innervated, more so than the arteries, by both adrenergic and peptidergic nerves.
- Noradrenaline and neuropeptide Y-containing nerves serve as vasoconstrictor components, they run along arteries and form a dense network around AVAs.
- Vasodilator peptides such as substance P, calcitonin gene-related peptide, and vasoactive intestinal polypeptide were found to accompany arteries and AVAs along the length of the dermal laminae.
Role in Acute Laminitis
- The research relates these findings to the development of acute laminitis, a painful and potentially crippling disease in horses.
- The study proposes that the release of vasoactive peptides from diseased organs elsewhere in the body may cause prolonged dilation of AVAs in the foot.
- This inappropriate dilation could lead to laminar ischemia, a restricting of blood flow, contributing to the development of acute laminitis.
Cite This Article
APA
Molyneux GS, Haller CJ, Mogg K, Pollitt CC.
(1994).
The structure, innervation and location of arteriovenous anastomoses in the equine foot.
Equine Vet J, 26(4), 305-312.
https://doi.org/10.1111/j.2042-3306.1994.tb04391.x Publication
Researcher Affiliations
- Anatomical Sciences Department, University of Queensland, St. Lucia, Brisbane, Australia.
MeSH Terms
- Adrenergic Fibers / chemistry
- Adrenergic Fibers / ultrastructure
- Animals
- Arteriovenous Anastomosis / anatomy & histology
- Arteriovenous Anastomosis / innervation
- Calcitonin Gene-Related Peptide / analysis
- Endothelium, Vascular / cytology
- Endothelium, Vascular / physiology
- Endothelium, Vascular / ultrastructure
- Female
- Foot Diseases / etiology
- Foot Diseases / physiopathology
- Foot Diseases / veterinary
- Hoof and Claw / anatomy & histology
- Hoof and Claw / blood supply
- Hoof and Claw / innervation
- Horse Diseases / etiology
- Horse Diseases / physiopathology
- Horses / anatomy & histology
- Immunohistochemistry
- Male
- Microscopy, Electron / veterinary
- Muscle, Smooth, Vascular / cytology
- Muscle, Smooth, Vascular / physiology
- Muscle, Smooth, Vascular / ultrastructure
- Neuropeptide Y / analysis
- Norepinephrine / analysis
- Substance P / analysis
- Vasoactive Intestinal Peptide / analysis
Citations
This article has been cited 5 times.- Blaettler C, Kaessmeyer S, Grabherr S, Koch C, Schweizer D, Van der Vekens E. Post-mortem Computed Tomographic Angiography in Equine Distal Forelimbs: A Feasibility Study. Front Vet Sci 2022;9:868390.
- Lancaster LS, Bowker RM. Acupuncture Points of the Horse's Distal Thoracic Limb: A Neuroanatomic Approach to the Transposition of Traditional Points. Animals (Basel) 2012 Sep 17;2(3):455-71.
- Zamboulis DE, Senior JM, Clegg PD, Gallagher JA, Carter SD, Milner PI. Distribution of purinergic P2X receptors in the equine digit, cervical spinal cord and dorsal root ganglia. Purinergic Signal 2013 Sep;9(3):383-93.
- Guedes JRB, Vendruscolo CP, Tokawa PKA, Carvalho AM, Johnson PJ, Faleiros RR. The Detection of Thoracolumbar Spine Injuries in Horses with Chronic Laminitis Using a Novel Clinical-Assessment Protocol and Ultrasonographic Examination. Animals (Basel) 2024 Apr 30;14(9).
- Castro-Mesa AF, Resende Faleiros R, Martínez-Aranzales JR. Transmural Ultrasonography in the Evaluation of Horse Hoof Internal Structures: Comparative Qualitative Findings-Part 1. Animals (Basel) 2023 Jun 10;13(12).
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