Farriery for the foal: A review part 1: Basic trimming
Reprinted with permission from Equine Veterinary Education (EVE).
|Fig 3: The width is wider at the coronet than at the groundsurface of the foot in this 6-week-old foal. Also note the pointedtoe.|
Trimming the foal
Birth to one month
At birth, the foal’s hoof is enveloped in a gelatinous perioplicmembrane (eponychium) which reduces the risk of trauma tothe mare’s reproductive tract during gestation and parturition(Fig 1). Shortly after birth, with the first steps of life, theperioplic membrane on the solar surface of the foot wears,dehydrates and retracts proximally on the hoof wall andultimately creates a sulcus of varying depths just distal to thecoronet the coronary band (Fig 2a and b). This depression,termed the sub-coronary groove, is considered normal andgrows distally towards the ground. In lay terms it is oftenreferred to as a ‘milk’ foot as it appears at birth andgenerally has grown out over the next 4–6 months byweaning. It has the potential to cause a defect or separationin the sole wall junction (white line) when it approaches theground surface of the foot if the toe length is allowed togrow excessively long. The remnants of the sub-coronarygroove create leverage at the toe if not trimmedappropriately and this force is responsible for a bending inthe dorsal hoof wall or separation at the sole wall junction inthe toe. The foal’s foot at this time is generally tapered, beingwider at the coronet and becoming narrower distally at theground surface (Fig 3). A foal`s foot does not only grow in adistal direction, but it also expands as it develops. As thefoal’s feet are tapered, expansion occurs proximally and asthe ground surface of the distal hoof is relatively small, theweight-bearing area is positioned in the dorsal section of thefoot. Exercise and appropriate trimming will enlarge the areaon the ground surface of the foot and move it in a palmar/plantar direction. The pointed or tapered appearance willgradually disappear in the first few months of life withappropriate trimming. In foals with acceptable limbconformation there is little need for trimming during the firstmonth of life.
Foals should be presented to the farrier at one month of agefor trimming. Prior to the first trimming, basic limb and footmanipulations by trained farm personnel should have the foalaccustomed to the positioning used by the farrier. Trimmingshould be a pleasant experience for the foal and will act asa form of imprinting if started in a gentle manner from thebeginning. The farrier should be patient, perform the farrierygently and efficiently and not fight the foal. An experiencedhandler that is gentle but firm is essential. The use of a nosetwitch or chemical restraint should be discouraged. If restraintis necessary, the author will use a piece of bailing twine thatis threaded through the rings of the halter and placed under the upper lip of the foal. Mild pressure or gentle tugs (neverharsh) are applied to the string if necessary while thetrimming is taking place. Generally, it is only necessary to usethis method during the initial trimming session. The foal isalways trimmed in a stall placed alongside the mare that ispositioned against the wall and backed into a corner. Theouter side of the foal is trimmed; then the positioning of themare is reversed, and the other side of the foal is trimmed.
All that is generally necessary at 1 month of age is tosquare the toe of the hoof with a rasp to remove thetapered or pointed contour of the dorsal distal hoof wallperimeter and encourage the foal to break over in thecentre of the foot. At this age, due to the pointed toe, thefoal may break over to either the outside or inside of the toe(Fig 3). If the frog has receded below the level of the hoofwall, the heels should be rasped lightly using the smooth sideof the rasp until the hoof wall and the frog are on the sameplane. Any sharp edges are removed from the perimeter ofthe hoof capsule using the rasp at an angle. As will bediscussed below, the use of a hoof knife or hoof nippers isdiscouraged when trimming foals at any age.
Two months onward
During these first few months of life, attention should bedirected towards the structural integrity of the hoof capsule(foot mass/density) rather than to cosmetics. The importantconcerns are to promote the growth of a thick, durable hoofwall, to ensure maximum sole thickness in order to protect thevulnerable sole wall junction, the soft tissue structure anddeveloping distal phalanx and finally to develop thestructures in the palmar/plantar section of the foot. Promotingthe structural mass of the foot in a foal (defined as a stronghoof wall, adequate sole depth and a solid heel base) is vitalfor hoof capsule development and future soundness. It is theauthor’s opinion that a hoof pick, wire brush and a rasp arethe only tools necessary to trim foals that are kept on amonth to 5 weeks trimming schedule. Furthermore, if the foalhas adequate exercise combined with a consistent trimmingschedule, there is generally minimal hoof growth whichmakes the use of a hoof knife and hoof nippers unnecessary.The goal is to not have the foal walk exclusively on the hoofwall but rather load all the structures on the solar surface ofthe foot; having the foot ‘load-sharing’ causes stimulation,adaptation and promotes growth. Foals that are trimmedfrequently and have a lot of horn removed tend to developweak fragile hoof capsules (O’Grady 2017).
The recommended technique of trimming foals used bythe author may differ from traditional farriery (O’Grady 2008,2017). Dirt and debris are removed from the sole and sulci ofthe frog using a hoof pick. The solar surface of the foot isthen cleaned vigorously using a wire brush to remove anyloose exfoliating horn. Any loose or exfoliating tags of hornare removed from the frog with a hoof knife if necessary.Otherwise, the ground surface of the foot and the frog areleft untouched which affords the foal ample protection onthe ground surface of the foot. Exfoliating horn from the solewill be continuously shed through the abrasive friction withthe ground as the foal exercises. The sole of a foal is relativelythin (which can be demonstrated by showing deformationwhen using thumb pressure or small hoof testers is applied tothe sole) and needs to develop as much thickness as possiblein order to protect the immature developing structures withinthe capsule. Removing excess sole with a hoof knife appearsto be the primary cause of sole bruising in foals and maypotentially lead to flexural deformities because of the painresponse (Hunt 2011; O’Grady 2012). The health of the footthroughout the animal’s life is based on developing goodsolid heel structures. The heel base includes the hoof wall atthe heel, the bars, angle of the sole, a thick digital cushionand a wide healthy frog. The bars should not be removed asthey are needed for strength and to stabilise the palmarsection of the hoof capsule.
After cleaning the foot, the heels of the hoof capsule arerasped gently from side to side until the rasp just contacts thefrog. The hoof wall at the heels will now be on the samehorizontal plane with the frog and the heels of the hoofcapsule will generally extend to the widest part of the frog.When the heels are trimmed in this manner, the frog willfunction as an expansion joint to keep the heels wide apartand share some of the weight bearing function. The excesshoof wall at the toe and quarters is then reduced asnecessary using a rasp placed at a 90° angle just dorsal tothe sole wall junction (white line) at the inner part of thestratum medium of the hoof wall (Fig 4a). When the desiredamount of hoof wall is removed, the outer sharp edgearound the perimeter of the foot that is formed by theangulation of the rasp is removed by running smooth side ofthe rasp around the perimeter of the hoof in a horizontaldirection thus creating a rounded edge (Fig 4b). This roundedge will help to prevent cracks and chips in the hoof wall.As the foal grows and develops, the foot assumes the samegrowth pattern as the adult horse which follows theangulation of the horn tubules in the hoof capsule; i.e. theheels and toe grow forward relative to the centre of rotation.Therefore, the same guidelines for trimming can be appliedto the juvenile horse; using the widest part of the foot,trimming the heels to the base of the frog and creatingapproximate proportions on either side of a line visualisedacross the widest part off the foot (O’Grady 2008, 2009,2017). There is a tendency not to trim the heels appropriatelyin a foal and the author believes this practice detracts fromthe proper development of the palmar section of the foot(Fig 5a and b). The farrier should abandon the concept oflowering the heels in the foal and perhaps consider thenotion of increasing the ground surface. The method of usingthe rasp on an angle leaves the hoof wall and the adjacentsole on the same plane allowing both structures to share thebulk of the weight when the animal moves. It also appears tostimulate the horn to grow thicker and stronger (O’Grady2008, 2017).
Foals given sufficient exercise do not grow an excessiveamount of hoof wall in the first few months of life and ourability to influence the foot/limb by excessive trimming onone side of the foot in the horizontal plane is limited andshould be discouraged. If it becomes necessary to lower oneside of the foot past the point of being level due to adeveloping hoof capsule distortion or in an attempt to affectlanding, it should not be lowered any more than fewmillimetres at one time. Trimming the foot at 2-week intervalsmay be useful when trying to change the medial lateralorientation of the foot or when trying to increase the groundsurface on one side of the foot.
The traditional theory of lowering the lateral side of thefoot on a foal that stands toed-out or lowering the medialside of the foot on a toed-in foal is unrealistic. In fact, it maybe detrimental as the cause of the foal having a toe-in ortoe-out stance generally reflects the conformation of the limband is rarely limited to the foot (Hunt and Baker 2017). Adeviation is generally found in the axial alignment of the limbabove the foot such as a rotational deformity of the limbdistal to the carpus or the fetlock; therefore, when one sideof the foot is trimmed excessively, the cosmetic appearancemay be improved temporarily but over time this practice willlead to distortion of the hoof capsule (compressed growthrings and the hoof wall rolling axially on the lowered side)resulting from an unequal load on the foot. This practice willalso place excessive and unequal forces on the physes andjoint on the side that is being trimmed excessively. The effectsof over trimming can be observed radiographically a fewdays after the trim (Hunt and Baker 2017; O’Grady 2017).
Rotational deformities are very common in foals andshould not be considered abnormal. For example, a narrowchest coupled with short neck and relatively long forelimbswill cause many foals to adopt a base-wide stance in front inorder to graze comfortably which will often be accompaniedby outward rotation of the entire limb. When viewed fromthe frontal plane, the entire limb will be rotated outwards,but the axial alignment of the limb will be relatively straight(Fig 6). This stance can be considered normal in foals as itconfers a higher degree of stability and is gradually modifiedas the transverse diameters of the upper body increase withgrowth. As the foal moves, it is quite noticeable that thelateral side of the hoof wall strikes the ground initiallybecause of the flight pattern caused by the rotated positionof the limb. These foals should be trimmed flat or level andnot have their feet lowered on the outside wall which is thetraditional practice. A base-wide stance in a 3- to 4-monthold foal will often result in asymmetric hoof capsules noted inthe frontal plane. The medial side of the hoof capsule will beslightly lower than the lateral aspect due to the landingpattern of the foot. If this stance is not recognised asphysiological for the age and an attempt is made to‘correct’ it by lowering the lateral wall, there may be a risk ofcreating an angular limb deformity where none existedpreviously. In cases where the medial heel bulb has beendisplaced proximally because of the asymmetrical landingpattern, although it may seem counterintuitive, the medialhoof wall is trimmed slightly more than the lateral side tocreate additional ground surface under the medial wall. Ifthe medial hoof wall begins to roll under axially, the authorhas seen improvement by placing a small compositeextension on the outer hoof wall that is used to createadditional ground surface and address this hoof capsuledistortion. Therapeutic trimming does not offer favourableresults in the mal-positioned limb, as this deformity iscorrected through growth. As the musculature of the chestincreases, the chest widens and the elbows are pushedoutward, which rotates the limbs inward.
Flexor tendon flaccidity
Excessive (flexor tendon) laxity in the newborn foal mostcommonly affects the fetlocks of the hindlimbs whereas theforelimbs generally involve the fetlocks and carpi; many foalswill improve spontaneously with good husbandry (asdescribed below) and no other treatment and will have agood prognosis. This condition is often seen in premature,dysmature or septic foals (Coleman and Whitfield-Cargile2017). When seen in the forelimbs, there is a ‘bowed’appearance to the limb when viewed from the side from alaxity of the flexor apparatus of the entire limb. The carpusand fetlock are hyperextended with the palmar surface ofthe pastern and fetlock on or close to the ground. There maybe subluxation of the distal interphalangeal joint (DIPJ)associated with deep digital flexor tendon laxity allowing thetoe of the foot to elevate off the ground. In hindlimb laxity,the DIPJ is almost always involved along with laxity noted inthe pastern and fetlock (Fig 7). Initial treatment is aimed atprotecting the soft tissues of the heels without over supportingthe fetlock which will further promote the laxity. This can beaccomplished by applying a self-adhesive pad (Equate®Moleskin Padding) cut in the shape of the heel bulbs. Thecondition tends to be self-limiting within a few days after birthas the foal gains strength and is allowed moderate exercise.However, the tendon laxity often persists and it is notuncommon to see a foal that still has digital hyperextensionat 3–4 weeks of age. Treatment is sequential depending onthe severity of the tendon laxity and the initial response of thefoal to treatment. Therapy begins with controlled exerciseallowing the foal access to a small area with firm footing for1 h, 1–2 times daily. If there is no response by the third daypost-partum, the author will place the foot on a small pieceof ¼ inch plywood and trace the foot leaving 2–3 cm ofextension beyond the heels. The plywood is attached to thefoot using a soft kling gauze to envelop the foot and thensecuring the extension to the foot using 2-inch elastic tapeapplied in a figure of 8 technique (Fig 8a,b and c). Theexercise schedule is continued and the bandages securingthe extensions are reset as necessary. The laxity will generallyresolve in 7–10 days and exercise can gradually beincreased. When presented with an older foal, even thoughthe toe is off the ground, the toe length of the hoof capsuleshould be reduced vertically or from the outer hoof wall sono leverage is applied to the toe when the ground surface ofthe hoof capsule is weight bearing following the applicationof an extension. The heels can be rasped gently from themiddle of the foot palmarly/plantarly to create additionalground surface in that section of the foot; some form of apalmar/plantar extension should then be applied whichextends approximately 3–4 cm beyond the bulbs of the heelsto relieve the biomechanical instability of the digit (Fig 9). Acuff-type extension shoe is commercially available or a thinaluminium plate can be fabricated as an extension shoe withthe aluminium bent at the toe to align with the dorsal hoofwall to hold it in place. The author feels that either type ofextension shoe should be attached with the hoof envelopedin gauze and attached with elastic tape applied in a figureof 8 pattern rather than a composite if the foal is less than3 weeks of age. This manner of attachment avoids excessiveheat being applied to the fragile hoof capsule when thecomposite cures and the detrimental consequences thatmay follow. Taping the extension in place also preventscontracture of the hoof capsule which occurs at the heelswhen an acrylic composite is used. Heel extensions shouldextend beyond the heel bulbs or further; if not of sufficientlength, the extension will serve as a fulcrum and worsen thesubluxation of the distal interphalangeal joint andmetatarsophalangeal joint. Regardless of the method ofapplication, the extensions should be changed at 7–10-dayintervals or sooner if indicated by the extension shifting.Bandaging the limb is contraindicated as the counterpressurewill further weaken the flexor tendons and promote laxity
Care should be taken to maintain the condition of thefeet while the tendon laxity is being addressed and long-termmaintenance of the feet may be necessary. Duringtreatment, the heels become distorted and the hoof wallgrowth is oriented dorsally which requires gradual re-shapingonce the tendon laxity is resolved. The heels of the hoofcapsule should be trimmed to the level of normal tubularalignment if possible and the heels of the hoof capsuleshould be on the same plane as the frog. If the foal hadbeen allowed to walk on the bulbs of the heels for anextended period of time, there may be a demarcation orgroove between the coronet and the heels of the hoofcapsule (Fig 10a). The author has been successful improvinghorn tubular growth and alignment by filling the groove withan acrylic composite (Fig 10b). The toe length should betrimmed or reduced as necessary. This process may require3–4 months to accomplish but over time a normal foot shouldand can be the result.
Routine hoof care in the first few months of life should neverbe taken lightly. The importance of good farriery in the foalplays a vital role in both the development of the hoof andthe conformation of the limb. Management of hoof capsulesand limbs during this juvenile period will often impact thesuccess of the foal as a sales yearling or mature soundathlete. Foal trimming should always be based on goodbasic farriery principles and the appropriate biomechanics.Hoof care in the foal should always be a joint venturebetween the veterinarian and the farrier. The importance ofmaintaining a good veterinarian-farrier relationship should beemphasised; the farrier is responsible for basic trimming withveterinary oversight and if orthopaedic disorders develop, thefarrier will have significant input with therapeutic farriery. Asound foot care programme is time-consuming whereasassembly-line trimming is quick and easy, but the former ismuch more beneficial with a better outcome. Flexural andangular limb deformities in foals will be covered in part 2 ofthis review.
Conflict of Interest
No conflicts of interest have been declared.
Declaration of Ethics