Advanced farriery knowledge: A study guide and AWCF theory course companion

By Sarah Logie

Advanced farriery knowledge is a concise guide for those studying towards the Worshipful Company of Farriers association exam. It is the first textbook to walk the student through the exam syllabus and gives guidance in areas where further reading is required. It is a study guide associated with the AWCF theory course run by the author, in assoc

• Language: English
• Publisher: Sarah Logie FWCF Ltd
• Release date: Oct 22, 2023
• ISBN: 9781739472719

Sarah Logie

Sarah Logie FWCFSarah served her apprenticeship in the Scottish highlands with Robin Pape and made history in 2006 by being the first ever female to qualify with honours.During the following year she worked abroad in the USA and New Zealand. In 2007 she set up S. Logie Farriery and furthered her experience by taking time away to work with other highly qualified farriers. Gaining knowledge in areas of farriery applications less commonly occurring in the highlands, she then went on to sit the Associate exam in 2012, passing with Distinction.As a result of seeing an increase in environmental related foot infections particularly seedy toe she embarked upon the Fellowship exam with an article published on the classification of types of seedy toe, then a thesis looking at the treatment of structural seedy toe by medication and filling.She successfully passed the exam in May 2017 and became one of only two women to hold the qualification. She has presented her thesis and her methods at some of the largest farrier events in Britain and it has been warmly received. She continues her work and has gathered further case studies that add to her initial Fellowship work.As part of the Farriery Tuition group set up by Jay Tovey FWCF she offers online tutoring for farriers looking to sit their higher exams. The theory exam preparation works well online and there is a consistent uptake by farriers from around the world. www.sarahlogiefwcf.com

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Advanced Farriery Knowledge

A study guide and AWCF theory course companion

Sarah Logie FWCF

Published by Sarah Logie FWCF. Kirkhill. Inverness

ISBN 978-1-7394727-0-2

© Copyright Sarah Logie 2023. All rights reserved.

Sarah Logie asserts her moral right to be identified as the author of this book.

It is not legal to reproduce, duplicate or transmit any part of this publication either by electronic means or in printed format without the prior written permission of the publisher. Recording of any of the contents of this publication is strictly prohibited.

Printed in the United Kingdom

Illustrations and photographs by and © Sarah Logie

Copyediting, design and layout by Daisy Editorial

Dedication

This book is dedicated to Robin Pape DipWCF.

For always supporting me and teaching me to ask ‘why?’

‘Think of ease and work on.’

Introduction

This book was written as a companion to the Associate of the Worshipful Company of Farriers (AWCF) theory preparation course run by Sarah in association with Farriery Tuition Ltd. It covers the syllabus as set by the Worshipful Company of Farriers (London).

When studying for the exam in 2010, Sarah compiled her study notes from the entire reading list. This book is the result of those notes and, along with the recommendations for specialist titles or in-depth studies, it is the starting place for those wishing to pass the exam.

Revision features

Throughout the book, key terms that you should use in the exam are in bold.

You will also find the following features to help you:

Additional resources

Books, websites and resources for further reading. You’ll find full details in the reading list at the end of this book.

Revision from Diploma

Things to revise that you learned in the Diploma.

Key points for your revision cards

Important knowledge for the exam.

Simple practical tasks

Tasks to help put your learning into practice.

Notes and tips

Useful extra information and tips.

Chapter 1: Osteology and arthrology

Osteology – the science and study of bones

For us as farriers, obviously the greatest study attention is given to the limbs. In particular, the bones of the carpus, tarsus and distal limb.

Bone is a living tissue that is made up of both organic and inorganic matter. It is a dynamic material and is constantly remodelling according to the forces put upon it throughout the animal’s life.

The organic component gives the bone its elasticity and makes up about 45% of the total tissue. It is mostly made up of bone collagen, which is a protein. The inorganic component makes up the remaining 55% and is composed of minerals, calcium (29%) and phosphorus (13%), plus sodium and magnesium, which form a definite pattern within the organic matrix. Bones start as a cartilage template in utero and ossification turns these templates to bone. Some sections remain as cartilage after birth to allow growth, and for us as farriers the physes (also referred to as the epiphyseal plates or growth plates) are important to maintain straightness in the limbs.

Bone remodelling occurs through the activity of bone-producing cells called osteoblasts and osteoclasts, which are bone-absorbing cells (Figure 1).

Figure 1: Growth of a long bone with direction of growth denoted by blue arrows.

Other than the sesamoid bones we are mostly dealing with long bones. The pedal bone (PIII) is considered in some texts to be a modified long bone. This has an outer cortical bone and inner cancellous bone. The cortical bone, when looked at under a microscope, has a definite structure where the minerals are arranged in concentric rings around a central canal through which the blood and nerve supply pass. This system is known as the Haversian system (Figure 2).

Figure 2: The Haversian system, showing bone structure.

Revision from Diploma

Components of bone.

Structure of long bones.

Growth (processes of increasing in length and width) and remodelling, repair and physis closure times.

Skeleton – limbs, including being able to draw and name all. Do not forget carpus, tarsus and stifle (required for the AWCF).

Key points for your revision cards

Bone cells – osteocytes.

Bone-producing cells – osteoblasts, found in periosteum, facilitate growth.

Bone-absorbing cells – osteoclasts, found in endosteum, facilitate growth in width by allowing the medullary cavity to increase in width and maintain its size in relation to the bone.

End of the long bone – epiphysis, made of cancellous bone, forms congruent joint and covered in articular cartilage.

Shaft of the long bone – diaphysis, made of cortical bone, gives length, contains the medullary cavity where red blood cells are produced by bone marrow.

Trabeculae – honeycomb of branching bone plates, the building blocks of spongy bone.

Periosteum – tough fibrous connective tissue, covers all the bone except the articular cartilage, protects and nourishes the bone. Fibres of tendons and ligaments directly communicate with it and facilitate the connection to the bone (Sharpey’s fibres).

Medullary cavity – hollow cavity surrounded by cortical bone, lined with thin layer of cells called the endosteum. Filled with connective tissue called bone marrow, red when young, yellow when old as increased fat content. Site of red blood cell production.

The periosteal and medullary arteries – supply the bone with blood, venous drainage occurs mostly near articular surfaces.

Physis or epiphyseal plates – found between the diaphysis and epiphysis. Chondrocytes produce cartilage cells, which increase length, ossification closes the plate.

Arthrology – the study of joints

Joints are a series of mechanical linkages that allow movement between two or more bones. They also transfer the load from one bone to the next, and when healthy this happens in an efficient and pain-free manner.

Joints are classified as one of three types:

Fibrous joints – these are where the articular surfaces are held together by fibrous tissue, for example the sutures of the skull. These joints have little or no movement.

Cartilaginous joints – these are where the articular surfaces are united by cartilage, either hyaline or fibrocartilage, for example the pelvic symphysis or intervertebral joints. There is slight movement in these joints.

Synovial joints – these are the ones we are most commonly concerned with and they are characterised by a joint capsule with a joint cavity, synovial fluid and articular cartilage. They are high-motion joints and capable of large ranges of motion (Figure 3).

Figure 3: A simple synovial joint.

When naming joints, the upper bone is used first, but its ending is changed to ‘o’. For example, metacarpal becomes ‘metacarpo’. The lower bone is second, so ‘metacarpophalangeal’ joint (MCPJ).

Revision from Diploma

The contents and structure of a synovial joint – a good drawing will be the quickest way to describe this structure.

Understand how the architecture (shape) of the joint helps the stability of the structure.

Understand the direction and range of movement of different joints (flexion, extension, rotation).

Be familiar with and understand the terms protraction, retraction, adduction and abduction.

Understand the bones and tissues associated with the joints of the limbs – we will cover these in more detail, but make sure you are up to speed at Diploma level.

Cartilage

There are two types of cartilage:

Hyaline – articular.

Fibrocartilage – as in the co-lateral cartilages.

Articular cartilage

Covers the ends of the bones. It is a two-phase material comprising hyaline and collagen fibres. These are orientated during development in response to tension. The cartilage will vary in thickness within the joint and will be thickest at the area of greatest pressure. It is made up of 70–80% water and has collagen fibrils, proteoglycan and chondrocytes. Chondrocytes are responsible for synthesising, organising and regulating the extracellular matrix of the articular cartilage (see ‘Further cartilage notes’).

Its function is to absorb concussion and resist torsion, to reduce friction by lubricating the joint with synovial fluid (see ‘Further cartilage notes’) and to aid congruency (meaning opposing surfaces are in constant contact).

The articular cartilage is nourished through diffusion from the surrounding tissues – the blood flow to the joint capsule and the bone, and some from the epiphyseal blood supply and from the synovial fluid itself.

Damage to the cartilage can only be repaired on the margin of the wounds, but the repair material is fibrocartilage so not a complete replacement.

Joint lubrication by synovial fluid happens in two ways:

Under low loads (boundary lubrication) a covering of glycoprotein provides the lubrication, but this is sheared off under high loads.

Under high loads (hydrostatic lubrication) a fluid film (squeeze film), which is a combination of joint fluid and interstitial fluid from inside the cartilage, gives lubrication to the joint.

Fibrocartilage

The co-lateral cartilages of PIII have a convex abaxial surface and a concave axial surface and they curve inwards towards the heel. They are thicker distally and attached to the palmar process of PIII, giving shape and structure to the palmar part of the foot. Due to poor blood supply, they are difficult to treat if infected (quittor) and are said to aid in expansion of the hoof capsule.

Further cartilage notes

Articular cartilage has four layers. From outer layer to inner layer these are:

Tangential layer (woven collagen fibres).

Transitional layer (active chondrocytes and collagen fibres).

Radiate layer (round cells in columns and collagen fibres).

Calcified layer (mingles with the osseous laminae of underlying bone).

The extracellular matrix is the tissue surrounding the chondrocytes, where water, collagen and proteoglycans are found. The collagen forms a fibrillar network within the extracellular matrix, which maintains the shape and strength of the tissue (think of a sponge – it’s the bits between the holes!).

The proteoglycans are large negatively charged macromolecules (the largest and most common are called aggrecan molecules – think of them as antisocial), a mixture of proteins and long chains of sugar that attract water but repel each other.

During weight bearing the aggrecan molecules become even more tightly packed, which forces the water molecules out of the extracellular matrix (hydrostatic lubrication) and the negatively charged branches of the aggrecan molecules repel each other. This protects the bone and transfers load.

Think of squashing a sponge – the water comes out, but it does not disintegrate, and when you let go it bounces back to shape and draws the water back in (Figure 4).

Figure 4: Articular cartilage. Top – unloaded; bottom – loaded.

1. Tangential layer (woven collagen fibres).

2. Transitional layer (active chondrocytes and collagen fibres).

3. Radiate layer (round cells in columns and collagen fibres).

4. Calcified layer (mingles with the osseous laminae of underlying bone).

Chapter 2: Joints of the limbs and their ligaments

Ligaments – general

Structure

Made up of strong bands of fibrous (collagen) tissue. They link bone to bone or tendons to bone, or hold tendons in position as they pass along bones or over joints.

There are six main types of ligaments (with some subtypes) and the type relates to their function.

Interosseous ligaments

Interosseous literally means ‘between bones’.

These link bone directly to bone; they aid in the stabilisation of joints and tend to be quite short, which allows only limited movement.

A good example is the ligaments that hold the McII and McIV to the McIII. During a dissection, examine these ligaments to see how firmly they hold the bones in place.

Annular ligaments

These are flat fibrous sheets of tissue that wrap around the area of the limb holding all the tissues in place – specifically the tendons. This helps stabilise the joint and keeps the tendons where they should be whilst helping direct their pull over a joint.

Articular ligaments

Capsular or extraarticular ligaments are part of the outer fibrous layer of the articular capsule that surrounds synovial joints. They function as mechanical reinforcements enhancing the overall strength of the articular capsule.

Periarticular ligaments lie within the fibrous capsule, and both these and intra-articular ligaments are covered by a thin layer of synovium (connective tissue that lines the inside of the joint capsule).

Intra-articular ligaments are found within the joint capsule, for example the cruciate ligaments of the stifle or the impar ligament. They add stability in complicated joints, which can be under immense strain. These intra-articular ligaments are increasingly recognised as being involved in articular pathophysiology. Tearing and avulsion of intra-articular ligaments has been shown to create lesions in joints and may contribute to more complex lameness.

Check ligaments

These join tendons to bone to prevent tendon or joint damage through hyperextension – think of them as a ‘safety fail-safe’. They also form an important part of the stay apparatus through their ability to transfer load from the tendon directly to the bone. An example is the subcarpal or inferior check ligament of the deep digital flexor tendon (DDFT).

Collateral ligaments

These are found on the medial and lateral aspects of all joints and they stabilise the joint. They look like flat bands and help keep the joint moving in its correct direction.

Chondroungular ligaments (ligaments of the collateral cartilages)

There are three sets of ligaments that help secure the collateral cartilages to the phalanges.

There is a pair of elastic proximal ligaments or chondrocompedal ligaments. These attach the distal end of PI to the proximal palmar portion of the cartilage and the digital cushion; these ligaments are most prominent in larger horses, such as draft breeds.

The medial and lateral middle ligaments or chondrocoronal ligaments attach the proximal dorsal aspect of the cartilage to the proximal half of the PII.

The distal ligaments or chondroungular ligaments attach the cartilage to the PIII along the palmar process. The medial and lateral ligaments of the cartilages of the foot (collateral chondroungular ligaments) attach the cartilage to the angle of PIII (Figure 5).

Figure 5: Chondroungular ligaments.

A pair of chondrosesamoidean ligaments attach the axial surface of the cartilage to the navicular bone.

Cruciate ligaments of the cartilages of the foot (cruciate chondroungular ligaments) connect the axial surface of the cartilage to the palmar process on the opposite side of the foot (Figure 6).

Figure 6: Chondroungular ligaments.

Running through the digital cushion there are fibrous tracts radiating from the connective tissue ventral to the attachment of the DDFT (digital torus), through the digital cushion, to the axial surface of the cartilages of the foot. (Think of it like reinforcing mesh in a sole packing.)

The metacarpophalangeal joint or fetlock joint

The proximal sesamoids are held together as a pair by the palmar or intersesamoidean ligament. This ligament also has a high proportion of cartilaginous material, which provides a very smooth channel (known as the proximal scutum) between the bones that the tendons pass over and which almost fully encapsulates the bones (sesamoids) within it.

The abaxial (outer surfaces) of the sesamoids have attachment areas for two sets of collateral ligaments. These are called the deep and superficial collateral sesamoidean ligaments and form opposing tripods between the sesamoids, PI and McIII (Figure 7).

Figure 7: Deep collateral sesamoidean ligaments.

Superficial to these attachments there are also attachment areas for the