The Detrimental Effects of Toe Grabs - Thoroughbred Racehorses at Risk

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The Detrimental Effects of Toe Grabs -
Thoroughbred Racehorses at Risk

• Presented by Bill CasnerApril 2007
• Endorsed by The Jockey Club, The Grayson-Jockey
  Club Research Foundation and The Kentucky
  Horseshoeing School

Kentucky Horseshoeing School
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1. The Problem
Photo by Z
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2. Documented Contributors to Injury

• Thoroughbred Anatomy
• Toe Grabs

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Thoroughbred Race Horse Anatomy

• Age
• Bone structure is not completely matured in 2-5
  year-olds
• Hoof is not completely matured
• Pastern Length
• Long pasterns tend to facilitate underslung heels
• Underslung heels are correlated to decreased
  arterial blood perfusion which effects growth
  rates of the heels
• Hoof TypeThin walls, lack of cartilage mass,
  smaller hooves
• Source 2003. Contrasting structural morphologies
  of good and bad footed horses. Bowker, R.M.
  Proceedings 49th AAEP Convention, New Orleans,
  Louisiana

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Scientific Research on Toe Grabs

• Scientific studies conducted at top research
  centers show that toe grabs increase the risk of
  injury.
• For example 90.5 of horses experiencing
  catastrophic injuries wore toe grabs

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Documented Research Results

• Catastrophic injuries
• Toe grabs were present on 90.5 of horses
• Greater risk of catastrophic injury for long
  toe, underslung foot types
• Suspensory apparatus injuries
• 15.6 greater chance of suspensory apparatus
  failure with toe grabs than without

Sources in order of use 1996. Postmortem
evaluation of homotypic variation in shoe
characteristics of 201 Thoroughbred racehorses.
Kane, A.J. et al. AJVR.57 1141-1146. 2001.
Underrun heels and toe-grab length as possible
risk factors for catastrophic musculoskeletal
injuries in Oklahoma race horses. Balch, Olin k.
et al. vol.47, AAEP proceedings 2001.Risk
factors for and outcomes of noncatastrophic
suspensory apparatus injury in Thoroughbred
racehorses. Hill AE, Stover GM, et al. JAVMA.
218 1136-1144 1996. Horsehoe characteristics as
possible risk factors for fatal musculskeletal
injury of Thoroughbred racehorses. Kane, A.J. et
al. AJVR. 571147-1152
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Documented Research Results (continued)

• Harder racetrack surfaces are associated with
  increased risk for fatal injuries
• 1 billion economic impact of musculoskeletal
  injuries in the Thoroughbred racehorses
• Up to 83 of Thoroughbred racehorse deaths can be
  contributed to an exercise-related injury

Sources in order of use 2001. Racehorse
injuries, clinical problems and fatalities
recorded on British racecourses from flat racing
and National Hunt racing during 1996, 1997 and
1998. Williams, R.B. et al. Equine vet J. 33,
478-486 1998. Epidemiologic studies of racehorse
injuries. Kobluk, C.N. Current Techniques in
Equine Surgery and Lameness, 2nd edn., Eds N.A.
White and J.M. Moore, W.B Saunderes Co. pp
564-569 1994. Causes of death in racehorses over
a 2 year period. Johnson, B. J. et al. Equine
vet. J. 26, 327-330
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What are the odds?

• The odds of catastrophic injury in racehorses
  shod with toe grabs on front shoes is 1.5 times
  the odds in horses shod without toe grabs.

• Source 2004. Evaluation of horseshoe
  characteristics and high speed exercise history
  as possible risk factors for catastrophic
  musculoskeletal injury in Thoroughbred
  racehorses. Jorge A. DVM, MPVM, PhD Scollay, C.
  DVM, et al. AJVR. Vol 66, No. 8, pp 1314-1320

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What are the odds?

• For horses shod with low toe grabs compared to
  horses shod without toe grabs on front shoes
• Fatal musculoskeletal injury (FMI) 1.8x
• Suspensory apparatus failure (SAF) 6.5x
• Cannon bone condylar fracture (CDY) 7.0x

• Source 2004. Evaluation of horseshoe
  characteristics and high speed exercise history
  as possible risk factors for catastrophic
  musculoskeletal injury in Thoroughbred
  racehorses. Jorge A. DVM, MPVM, PhD Scollay, C.
  DVM, et al. AJVR. Vol 66, No. 8, pp 1314-1320

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What are the odds?

• For horses shod with regular toe grabs compared
  to horses shod without toe grabs on front shoes
• Fatal musculoskeletal injury (FMI) 3.5x
• Suspensory apparatus failure (SAF) 15.6x
• Cannon bone condylar fracture (CDY) 17.1x

• Source 2004. Evaluation of horseshoe
  characteristics and high speed exercise history
  as possible risk factors for catastrophic
  musculoskeletal injury in Thoroughbred
  racehorses. Jorge A. DVM, MPVM, PhD Scollay, C.
  DVM, et al. AJVR. Vol 66, No. 8, pp 1314-1320

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3. The Mechanics of Toe Grabs

• How do shoes with toe grabs affect foot
  function?
• They result in a broken-back hoof pastern axis
• They increase the degree that the sole flattens
• They cause the hoof wall to distort more
• They facilitate under run heels
• They magnify the hyperextension of the fetlock
  joint

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Normal Hoof/Shoe Impact

• THE PHASES OF THE STRIDE
• Ground contact
• Slide phase
• Loading phase
• Heel lift off
• Breakover

• The hoof approaches the track and begins to enter
  the surface
• The hoof and leg slide forward
• The ankle and hoof load
• The toe holds its position and the heel rises
  upward
• The toe breaks over and hoof leaves the surface

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5
2
4
3
Ground contact SLIDE SLIDE Heel lift
Breakover
Source 2007. Abnormal Forces Associated with
Toe Grab Horse Shoes, Rob Gillette, DVM, MSE
Mick Peterson, Ph.D. Raoul Reiser, Ph.D.
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Toe Grab Entrance

• As the toe enters the surface, the toe caulk acts
  as a wall, compacting the surface material in
  front of it, impeding the slide phase

• At the same time the hoof is compacting the
  surface material below it.
• The distal leg continues its forward momentum.

CUSHION
BASE
Source 2007. Abnormal Forces Associated with
Toe Grab Horse Shoes, Rob Gillette, DVM, MSE
Mick Peterson, Ph.D. Raoul Reiser, Ph.D.
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Toe Grab Exit

• The toe caulk is fixated within the compacted
  surface material.

• This increases the forces needed for breakover
  and toe-off to occur

Source 2007. Abnormal Forces Associated with
Toe Grab Horse Shoes, Rob Gillette, DVM, MSE
Mick Peterson, Ph.D. Raoul Reiser, Ph.D.
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Loaded Leg Sequence Both pictures are of same
foot loaded equally
6
5
300 lbs
300 lbs
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4
3
1200 lbs
1200 lbs
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3
1.5
3000 lbs
3000 lbs
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Sagital Section of Same Foot
Whats happening inside the hoof?
300 lbs
300 lbs
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Notice how much more the sole flattens
1200 lbs
1200 lbs
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Notice the degree of wall deformation
Normal heel compression Excessive heel
compression


3000 lbs
3000 lbs
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4. The Solution

• Eliminate the use of toe grabs (Banned in
  California in April 2007)
• Continue to fund quantifiable research in equine
  lameness
• Require continuing education on shoeing and hoof
  care as well as certification for farriers
• Encourage additional state racing commissions and
  racetracks to ban use of toe grabs

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• Special thanks to
• The Jockey Club, The Grayson-Jockey Club Research
  Foundation, The Kentucky Horseshoeing School and
  to the Welfare and Safety of the Racehorse
  Summits Horseshoeing Task Force for providing
  the background and support for this presentation.
  Prepared by Mitch Taylor and Kimberly Brown.

Kentucky Horseshoeing School