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Superficial digital flexor tendonitis in Thoroughbred race horses


  Clinical article

 Superficial digital flexor tendonitis in
 Thoroughbred race horses: outcome following
 non-surgical treatment and superior check
Department of Veterinary Clinical Sciences, Massey University, Palmerston North, New Zealand

   Objective This study documents the results of non-surgical treatment and treatment by superior check desmotomy in
   Thoroughbred racehorses with superficial digital flexor (SDF) tendonitis.

   Design        A prospective study was made of 124 thoroughbred racehorses with unilateral or bilateral SDF tendonitis.

   Procedure The flexor tendons were assessed by physical and ultrasonographic examination before treatment, and the
   lesions detected in affected tendons were characterised according to lesion type, length and cross-sectional area. Ninety
   three horses were managed non-surgically and 31 by superior check desmotomy. Recurrent or new injuries were defined
   as injuries affecting a previously injured superficial digital flexor tendon, the contralateral SDF tendon, or the suspensory
   ligament (interosseous muscle) in either forelimb.

   Results     No statistically significant difference was found in ultrasonographic lesion severity between treatment groups.
   Horses managed by superior check desmotomy were 1.3 times more likely to complete five or more races than horses man-
   aged non-surgically (95% confidence limits 0.93-1.82). Horses treated surgically were 1.2 times more likely to develop
   recurrent or new injuries after returning to training than horses managed non-surgically (95% CL 0.95-155).Horses under-
   going superior check desmotomy were 5.5 times more likely to develop suspensory desmitis than horses treated non-sur-
   gically (95% CL 1.13-26.4). There was no difference in the time to recurrent or new injury between treatment groups.

   Conclusion There was no statistically significant difference between treatment groups in the proportions of horses able
   to complete five or more races after an episode of superficial digital flexor tendonitis. Superior check desmotomy did not
   appear to offer an advantage over non-surgical treatment in preventing recurrent or new injuries in Thoroughbred race-
   horses. Horses undergoing superior check desmotomy appeared to be at greater risk of developing suspensory ligament
   injuries than horses managed non-surgically.
   Aust Vet J 1997;75:631-635
   Key words: Horse, tendonitis, superficial digital flexor tendon, Thoroughbred.

   SDF          Superficial digital flexor

                                                          Thoroughbred racehorses, and 69%’ to

    njury to the S D F tendon in                                                                    University Veterinary Clinic (MUVC)
    Thoroughbred racehorses is a                          71 %’ for Standardbreds. Data are lack-   between September 1391 and January
    common and career-threatening                         ing on success rates for Thoroughbred     1995, were included in a prospective
injury. Recovery from such injury is                      racehorses managed by non-surgical        study. Horses with injuries secondary
prolonged, and recurrence frequent                        methods for SDF tendonitis. T h e pur-    to    lacerations,  horses without
after affected horses return to training                  pose of this study was to document the    detectable SDF tendonitis, and those
or racing.’ Recently, superior check                      results of non-surgical treatment and     with inadequate follow-up were
desmotomy (transection of the acces-                      treatment by superior check desmotomy     excluded.
sory ligament of the S D F muscle) has                    for SDF tendonitis in New Zealand
                                                          Thoroughbred racehorses, and to           History and physical examination
been suggested as a treatment to reduce
                                                          determine risk of recurrence of injury       O n the day of examination, a
this high recurrence rate.?’ ‘Success’
                                                          in these two groups of horses.            detailed history was taken from the
following treatment for tendonitis has
                                                                                                    owner or trainer, and horses examined
been determined by the proportion of
                                                          Materials and methods                     for lameness at the walk and trot. T h e
treated horses able to compete in five
                                                            One      hundred     twenty    four     tendinous structure affected, the pres-
or more races postoperatively, without
                                                          Thoroughbred racehorses with injuries     ence and severity of lameness, and the
recurrence of injury.6 Reported success
                                                          to the S D F tendon in the metacarpal     amount of swelling and pain on palpa-
rates following superior check desmo-
                                                          region, presented at the Massey           tion were recorded. The presence of
tomy vary from 52%’ to 67%” for

Awt Vet/ Vol 75, No 9, September 1997                                                                                                   63 1
abnormalities unrelated to the flexor          Table 1. Ultrasonographic grading system             Zealand Racing Conference. Further
                                               used to describe core lesions in SDF tendon          information was obtained by telephone
tendons (for instance joint effusion)          according to Genovese et ai?
was also noted.                                                                                     interview with the owner or trainer o f
                                               Type 1   Lesion slightly hypoechoic compared         the horses, and from medical records in
Ultrnsonogr/lphirexamination                            to normal tendon.                           cases which were returned for re-exam-
    Before ultrasonographic examination,                Lesion is halt echogenic, and halt          ination. Follow-up intervals varied
                                               Type 2
the hair was clipped from the palmar                    anechoic.                                   from 1.5 to 4.5 years from the time of
surhce of the affected limbs, from the                  Lesion is mostly anechoic, represent-       first examination.
                                               Type 3
accessory carpal bone to the ergot or, in               ing significant fibre tearing.                  Horses were classified as: ( 1 ) retired
some cases, the coronary band. The                                                                  from racing without returning to train-
                                               Type 4   Lesion is totally anechoic, with almost
skin over the site to be examined was                   total fibre tearing and haematoma           ing, (2) retired for reasons unrelated to
thoroughly wetted, and coupling gel                     formation.                                   flexor tendon injury before completing
applied. Ultrasonographic examina-                                                                   five races, ( 3 ) did not race because of
tion of the flexor tendons was per-                                                                  recurrent or new injury to the flexor
formed in sagittal and dorsal planes,          addition to rest with or without a pro-               tendons or suspensory ligament during
 using a linear 7.5 M H z micro-probe          gram of controlled exercise.                          training, (4) raced one to four times,
 (Toshiba Ultrasound System Model                 Non-surgical management consisted                  but ceased training because of recur-
 SAL-55AS, with linear 7.5MHz micro-           of rest, with the recommended area of                 rent or new injury, or (5) raced five or
 intra-operative probe IOE-702V.               confinement being based on the sever-                 more times, with or without recurrent
 Toshiba, Japan). Images were recorded         ity of the tendonitis. For horses with                injury.
 on medical imaging film (Fuji Medical         anechoic core lesions or severe diffuse                   Recurrent or new injuries were
 Imaging Film MI-NH, blue base, Fuji,          tendonitis, stall rest with daily walking             defined as recurring injury to the same
Japan).                                        in-hand was recommended. Despite                      SDF tendon, new injury to the con-
     Ultrasonographic findings were cate-      this, most horses were paddock rested.                tralateral S D F tendon, or injuries
 gorised according to lesion type,             For horses with hypoechoic lesions,                    affecting the suspensory ligament in
 length, and the approximate cross-            controlled exercise was recommended.                   either forelimb subsequent to a previ-
 sectional area of the tendon affected         This consisted of walking and trotting                 ous SDF tendonitis. Horses that were
  (< 25%. 25-50%, > 50%). Limitations          under saddle o n level ground.                         still racing without recurrent or new
  in equipment capability precluded            Compliance with these recommenda-                      injury, but which had not yet complet-
  more accurate documentation of cross-        tions was highly variable, and many                    ed five or more starts, were considered
 sectional area of the lesion. Core            horses were not returned for re-exami-                 ‘untested’,h and were not used in calcu-
  lesions were graded on a scale of type I      nation at the recommended times.                      lations.
  to 4, according to the method                    Superior check desmotomy was per-
  described by Genovese et al-(Table 1).        formed on 31 horses using the proce-                 Statisticid analysis
  I n addition to these four grades, some       dure described by Turner and                            Data were entered into a comput-
  lesions were described as diffuse. These      McIlwraith.*All but two horses had the               erised data base program (Microsoft
  lesions had a generalised anechoic or         surgical procedure performed at                      Access for Windows 95 Version 7.0,
  hypoechoic appearance throughout the          Massey University. Two horses, one of                Microsoft Corporation, USA) and
  tendon, but were poorly defined, with         which had unilateral, and the other                  analysed using a statistical software
  few or no short linear echoes present.        bilateral surgery, were surgically treated           package (NCSS for Windows Version
   Horses examined more than 3 months           in Australia but recuperated in New                  6.021, Number Cruncher Statistical
  after occurrence of the original tendon       Zealand. Nine horses with unilateral                 Software, USA). During the statistical
   injury were assessed ultrasonographi-        SDF injuries, treated early in the study             analysis, the following parameters were
  cally for healing characteristics, but the    (1991, 1992), were treated by unilateral             used as outcome variables: recurrence
   lesions were not graded for compari-         superior check desmotomy. Two horses                 of tendon injury, occurrence of new
   son. In these cases, the ultrasonograph-     subsequently developed S D F ten-                    injury to the flexor tendons or suspen-
   ic assessment was used in recommend-         donitis in the contralateral limb, and               sory ligament, time to recurrence of
   ing the amount of exercise that the          all since then have been treated with                injury and time to occurrence of new
   horse should be permitted. In horses         bilateral superior check desmotomy.                  injury. Categorical type risk factors,
   with acute or resolving injuries of the       Surgery was performed with the horse                including affected limb (left or right)
   SDF tendon, serial ultrasonographic           in lateral recumbency in 29 cases, and              and treatment category (surgical or
   re-examinations during the recovery           in dorsal recumbency in 2 cases.                    non-surgical), and continuous type risk
   phase were recommended.                                                                           factors, including length, type and
                                                                                                      approximate cross-sectional area of the
  fieatment                                       Race records for horses returning to
                                                                                                      ultrasonographic lesion, were used as
    After ultrasonographic diagnosis, the       racing were obtained from the New
  owner or trainer of each horse made a
  choice between non-surgical manage-            Table 2. Age distribution ot 124 Thoroughbred horses with   SDF tendonitis.
  ment (rest alone, or rest plus a program
                                                 Age (years)              2                  3          4                  5          6 and over
  of controlled exercise) or surgical treat-
                                                 Number (%)           9 (7.3%)          32 (26%)    29 (23.3%)          20 (16%)      34 (27.4%)
  ment (superior check desmotomy) in

independent variables in the following
statistical analyses. Ultrasonographic
lesion characteristics (length, type,
cross-sectional area) were compared
between treatment groups using the
Mann-Whitney test and the chi-square
test to assess if there was a difference
between the sample of horses included
in each treatment group. The statistical
association between risk factors and
each outcome variable was assessed
using relative risk and its 95% confi-
dence limits (95% CL), the Mann
Whitney U test, or the Logrank test,
depending on the scale of measure-











ment. Time to recurrence was analysed                       IPercentage of horses in each Category      H Affected region of tendon
using the Kaplan-Meier Product Limit
Estimator.                                     Figure 1. Distribution of lesions detected ultrasonographically in the SDF tendons of 124
  Statistical significance was defined as      Thoroughbred racehorses. The SDF tendon in the metacarpal region has been divided
P < 0.05, 95% CL for relative risks            into three zones.7 The middle and distal thirds of the tendon were most commonly
which did not include 1, and statistical       injured, although 29% of horses had injuries involving most of the length of the SDF tendon.
power was estimated using P = 0.05.

                                               don is shown in Figure 1. Type 1                      shown in Table 3. New or recurrent
Results                                        lesions were documented in 17 cases                   injuries occurred between the time the
History and physical examination
                                               (1W o ) , type 2 in 13 cases (14%), type              horse resumed training and 36 months
   Of the 124 Thoroughbred racehorses
                                               3 in 13 (14%). type 4 in 38 limbs                     (50th race) after initial examination for
included in the study, 33 were females,
                                               (42%), and i n 10 limbs (11%) the                     injury.
5 were entire males and 86 were geld-          lesions were classified as diffuse.                      Superior check desmotomy (n= 31) -
ings. The average age of the horses was
                                               Approximate cross-sectional area was                  Seventeen horses were treated by uni-
4.5 years (SD * 1.7 years), with a range       documented in 88 horses with injuries                 lateral or bilateral superior check
from 2 to 10 years. The age distribu-
                                               of < 3 months duration. In 44 cases                   desmotomy for a first episode of SDF
tion of horses is shown in Table 2.
                                               (500/o), the lesion occupied less than                tendonitis, and 14 horses were under-
Thirty seven horses (30%) had not
                                               25% of the cross-sectional area of the                going treatment for recurrent episodes.
raced at the time of initial presentation,
                                               tendon, in 28 cases 25-50% and in 16                     N o horses in this category were
18 horses had raced between 1 and 4
                                               cases over 50%.                                       retired from racing before returning to
times, 32 between 5 and 15 times, and
                                                                                                     training. Four horses were retired prior
37 horses had raced more than 15               Peiitment and outcome                                 to completing five races for reasons
times. In 91 cases the injury was < 3            Ninety three horses received non-                   unrelated to the flexor tendon injury,
months old at the time of examination.         surgical treatment and 31 were treated                including exercise-induced pulmonary
Fifteen horses were presented 3 to 6           by unilateral or bilateral superior check             haemorrhage ( I ) , death associated with
months after injury, and 17 were pre-          desmotomy.                                            colic (2) and an unspecified respiratory
sented more than 6 months after the              Non-surgical treatment (n=93)           -           condition (1).
time of injury. The duration of injury         From this group, 1 7 horses were retired                 T h e outcome for the 27 horses
was unknown in one case.                       without returning to training for various             which returned to training, and did not
  The left SDF tendon was affected in          reasons including severity of injury;                 retire for unrelated reasons, is shown in
52 cases, the right in 53 cases and both       advanced age of the horse, perceived                  Table 3. New or recurrent injury to the
SDF tendons in 19 cases. O f 114 cases         breeding value, concurrent injuries,                  flexor tendons or suspensory ligament
in which the results of lameness exam-         lack of ability, economic and other                   occurred between the time the horse
ination were recorded, 43 horses (37%)         unspecified reasons. Another 17 horses                resumed training, and the 48th month
were lame in the affected limb on the          were retired before they had completed                after examination for injury.
day of presentation and 10 (8.7%)              five races for reasons unrelated to flex-
were lame in another limb.                     or tendon injury including: unrelated                   Relationship between outcome vari-
                                               lameness or injury (12), lack of ability              ables and recurrence of injury
Ultrasonographic examination
                                               (4) or death (1). Although some of                       T h e relative risk of recurrent or new
   T h e length of the ultrasonographi-
                                               these horses were successful in alterna-              injuries in the right forelimb compared
cally detected lesion in the worst affect-
                                               tive careers of dressage, show-jumping                with the left forelimb was 1.19 (95%
ed limb was 8 cm or less in 52 cases,
                                               or eventing, they were not considered                 CL 0.88 to 1.6). No statistically signif-
between 10 and 16 cm in 30 cases, and
                                               in further analyses for this paper.                   icant difference was found when com-
20 to 24 cm in 9 cases. The distribu-
                                                  The outcome for the remaining 59                   paring ultrasonographic length of
tion of the lesions within the SDF ten-
                                               horses which returned to training is                  lesion, lesion type, or cross-sectional

Aust Vet/ Vol 75, No 9, September 1997                                                                                                     633
Table 3. Outcome for the horses that returned to training.                                                    demonstrated age-related alterations in
                                                                                                              the crimp morphology in the SDF
                                                  Conservative management     Superior check desmotomy
                                                           n = 93                       n = 31                tendon of wild horses which had not
                                                                                                              undergone training, and proposed that
'Untested' horses:                                                                                            training may accelerate the ageing
Retired after diagnosis, or raced < 5 times                 34                             4                  process within the tendon.
for reasons unrelated to flexor tendon injury
                                                                                                                  In order to compare the two treat-
Outcome of horses returning to training:                                                                      ments in this study, the groups of horses
Did not race because of recurrent or                     16 (27Yob)                     6 (22Yob)             were standardised as much as possible.
new injurya occurring during training                                                                         Although the owners made the deci-
                                                         10 (17%)                        2 (7%)
                                                                                                              sion o n treatment for their horses,
Raced 1-4 times but ceased training
because of recurrent or new injury                                                                            there was no significant difference in
                                                                                                              the ultrasonographic severity of lesion
Raced 1-4 times, still racing without injury               1 (2%)                           -
                                                                                                              between treatment groups. Even so,
Raced 5 or more times prior to, or without               32 (54%)                       1 9 (70%)
                                                                                                              horses managed by non-surgical meth-
recurrenffnew injury
                                                                                                              ods were subjected by their owners or
Recurrent or new injuries:                                                                                    trainers to a wide variety of exercise
Percentage of horses returned to trainingkacing          39 (66%)                       21 (78%)               regimens, and many of the horses were
which developed recurrent or new injuries
Developed suspensory desmitis after return                 2 (3%)                       5 (18%)
                                                                                                               not returned for reassessment of ten-
to training
                                                                                                               don injury prior to returning to train-
                                                                                                               ing. Horses which did not return to
aRecurrent injury to the previously affected SDF tendon, or new injury to the contralateral SDF tendon or a
                                                                                                               training, or which retired from training
suspensory ligament.
bPercentage of horses which returned to training, and did not retire for unrelated reasons.                    for reasons unrelated to tendon injury
                                                                                                               were not considered useful subjects for
                                                                                                               statistical comparison. Recurrent
 area between treatment categories (for                    Discussion                                          injuries to the same tendon and
 length of lesion z = -0.91, P = 0.36; for                    Thoroughbred horses in New                       injuries to the contralateral tendon
 lesion type (2 = 0.31,2 df, P = 0.86; for                 Zealand race o n turf tracks, in a clock-           were considered together because
 cross-sectional area (2 = 0.76, 3 df, P =                 wise or anti-clockwise direction                    owners and trainers sometimes had
 0.86). N o difference was found in                        depending on the location of the race-              difficulty recalling which limb was
 ultrasonographic characteristics of                       track. A relatively large proportion of             originally affected, and they interpreted
 lesions in horses with or without re-                     horses race to the age of 6 years in flat           a new tendon injury as failure of treat-
 injury using the Mann Whitney U test                      races, and some continue beyond that                ment, whether it affected the originally
 (for length of lesion z = -0.60, P = 0.55;                age in hurdle races and steeplechase                injured limb or not.
 for lesion type z = 0.67, P = 0.50; for                   events. T h e age distribution of affected              Injuries to the suspensory ligament
 cross-sectional area z = 0.23, p = 0.82).                 horses, and the equal proportion of left            were considered to be related, new
    There was no statistically significant                 and right forelimbs affected by injury,              injuries. T h e suspensory ligament sup-
 difference between the survival curves                    probably reflect the local racing popu-              ports the fetlock joint in extension.
 (Figure 2) for time to recurrent or new                   lation and conditions. Where anti-                   Suspensory ligament injuries occurred
 injury between right and left forelimbs                   clockwise racing predominates, other                 in both treatment groups subsequent
 or between surgically and non-surgically                  authors have found that a large propor-
 treated horses (forelimb: (2 = 0.68, df = 1,              tion of tendon injuries occur in the left
  P = 0.41; treatment: (2 = 1.29, df = 1,                  forelimb of Thoroughbred racehorses.",'"
  P = 0.26).                                                   Forty four per cent of horses were
     Horses undergoing superior check                       presented for evaluation of tendon
 desmotomy were 1.3 times more likely                       injury before their fifth race start. This
  to complete five or more races than                       group of horses sustained injury during
  horses treated non-surgically (95% CL                     preparation for racing, or during their
  0.93 to 1.82; power = 0.28). There was                    first few starts. A similar observation
  no significant difference in the risk of                  was made by Rooney and Genovese" of
  recurrent or new injuries between the                     horses racing in the United States.
  two treatment groups, although the                        They concluded that fatigue due to
  relative risk of new injury was slightly                  lack of fitness may have contributed to
  higher (1.18) in the horses undergoing                    the large proportion of injured horses
  surgical treatment (95% CL 0.9 to                         in this group. In this study, however, a                        Months after injuly
   1.55; power = 0.19). Horses treated by                   large proportion of affected horses were
  superior check desmotomy were 5.46                        mature. Older horses may be predis-                Figure 2. Kaplan-Meier survival curves
  times more likely to develop suspensory                   posed to SDF tendonitis by naturally               showing proportion of horses still racing
  desmitis than those treated non-surgi-                    occurring, age-related changes in crimp            without recurrent or new injury after
  cally (95% CL 1.13 to 26.4).                               formation in the central core of the              surgical (solid line) and non-surgical
                                                             SDF tendon.'*,I3Patterson-Kane et all2            (dotted line) treatment.

  634                                                                                                          Aust Vet/ Vol75, No 9, September 1997
   to an episode of S D F tendonitis,           limited by the number of horses avail-        study, and Vanessa Tilson for technical
   although were 5.5 times more likely to       able for complete follow-up, however.         assistance.
   occur in horses after superior check         While a larger proportion of horses
  desmotomy. Hawkins and Ross4                  were able to complete five or more            References
  observed an apparently high incidence         races after undergoing superior check          1. Genovese RL. Reef VB, Longo KL, Byrd JW.
                                                                                              Davis WM. Superficial digital flexor tendonitis:
  of suspensory desmitis in a group of          desniotomy, surgically treated horses         Long term sonographic and clinical study of race-
  Standardbred racehorses which were            appeared to be at greater risk of devel-      horses. In: Rantanen NW. Hauser ML, editors.
  treated by superior check desmotomy           oping recurrent or new injuries,              Proceedings of the 1996 Dubai lnternational
  for SDF tendonitis, but were unable to        including suspensory desniitis, than          Equine Symposium: The equine athlete: tendon.
                                                                                              ligament and soft tissue injuries. Veterinary Data,
  make comparisons with a group of              horses managed by rest and controlled         Wildomar, California, 1996:187-205.
  horses treated non-surgically. They           exercise.                                     2. Bramlage LR. Superior check desmotomy as
  speculated that transection of the supe-         In this study, horses were followed to     a treatment for superficial digital flexor tendonitis:
                                                                                              initial report. Proc Am Ass Equine Pract
  rior check ligament may result in             the time of recurrent or new injury, or
  hyperextension of the carpus or fetlock       in many cases, to the end of their rac-       3.Fulton IC. MacLean AA, OReilly JL, Church S.
  joint, and therefore predispose to sus-       ing careers. Recurrent or new injuries       Superior check ligament desmotomy for treat-
  pensory desmitis. Superior check              occurred between the time the horse          ment of superficial digital flexor tendonitis in
                                                                                             Thoroughbred and Standardbred horses. Aust
  desmotomy on cadaver limbs resulted           returned to training and 48 months            Vet J 1994;71:233-235.
  in hyperextension of the fetlock joint       after the time of first injury. Although      4. Hawkins JF, Ross MW. Transection of the
  and carpus, and increased strain on the       many horses were able to complete five       accessory ligament of the superficial digital flex-
  S D F tendon but not the deep digital                                                      or muscle for the treatment of superficial digital
                                               or more races after an episode of S D F
                                                                                             flexor tendonitis in Standardbreds: 40 cases
  flexor tendon.14 Strain on the suspensory     tendonitis, recurrent or new injuries to                  J
                                                                                             (1988-1992)A m Vet Med Ass 1995;206:674-678.
  ligament was not measured in that            the flexor tendons or suspensory liga-        5. Hogan PM. Bramlage LR. Transection of the
  study, but would be expected to               ments limited the careers of a large pro-    accessory ligament of the superficial digital flex-
                                                                                             or tendon for treatment of tendinitis: long term
  increase with hyperextension of the          portion of cases.                             results in 61 Standardbred racehorses (1 985-
  fetlock joint.                                   Prospective studies involving clinical    1992).Equine Vet J 1995:27:221-226
     No significant associations were          cases suffer many important limita-           6. Bramlage LR, Rantanen NW, Genovese RL.
 found in this study between ultrasono-        tions and this study was no exception.        Page LE. Long-term effects of surgical treatment
                                                                                             of superficial flexor tendinitis by superior check
 graphic features of the injury and the        T h e number of horses available for          desmotomy. Proc Am Ass Equine Pract
 likelihood of recurrence. This is in con-     complete follow-up was limited, as            1988;34:655-656.
 trast to the findings of Genovese et al,'     many horses developed unrelated               7. Genovese RL, Rantanen NW, Simpson BS.
                                                                                             The use of ultrasonography in the diagnosis and
 who found that the greater the cross-         injury or illness or were retired because
                                                                                              management of injuries to the equine limb. Comp
 sectional area and length of the lesion,      of lack of ability, thereby preventing         Cont Educ Pract Vet 1987;9:945-955.
 the greater the likelihood of recurrence      f d l evaluation of treatment for S D F       8. Turner AS, Mcllwraith CW. Superior check lig-
 of injury when the horse returned to          tendonitis. It was difficult to ensure        ament desmotomy (after Bramlage). In:
                                                                                              Techniques in large animal surgery. 2nd edn.
 training. Similarly, Yovich et all" corre-    compliance with recommended treat-            Lea and Febiger. Philadelphia, 1989:147-149.
 lated increased lesion length with a          ment strategies, with horses in both          9.Wilson JH. Robinson RA, Jensen RC, McArdle
 greater likelihood of re-injury. Cross-      groups receiving widely varied exercise        CJ. Equine soft tissue injuries associated with
 sectional area was not accurately docu-      programs during recovery from injury.          racing: descriptive statistics from American race-
                                                                                             tracks. In: Rantanen NW, Hauser ML, editors.
 mented in this study, and many horses         I n addition, owners had difficulty           Proceedings of the 1996 Dubai lnternational
 were not presented for treatment until       recalling exact details in cases of re-        Equine Symposium: The equine athlete: tendon.
 several weeks to months after injury,        injury, making it impossible to separate       ligament and soft tissue injuries. Veterinary Data,
                                                                                             Wildomar. California. 1996:l-21,
 thus affecting the ultrasonographic          recurrent from new injuries in the             10. Yovich JV. Sawdon H. Booth T. Robertson
 type of lesion documented at the time        analysis of results. Nevertheless, the         ID. Correlation of ultrasonographic findings and
of examination.                               results of this study suggest that,            long term outcome in racehorses with superficial
    Superior check desmotomy has been         despite treatment and apparent recov-          digital flexor tendon injury. Aust Equine Vet
suggested to reduce the risk of recur-        ery, there is a high incidence of recur-       11. Rooney JR. Genovese RL. A survey and
rence of injury in horses returning to        rent or new injury in Thoroughbred             analysis of bowed tendon in Thoroughbred race-
training following recovery from S D F        racehorses returning to training and           horses. Equine Vet Sci 1981 $49-53.
tendonitis.? According to the results of      racing following an episode of SDF             12.Patterson-Kane JC. Firth EC, Goodship AE,
                                                                                             Parry DAD. Age-related differences in collagen
this study, the risk of recurrent and         tendonitis.                                    crimp patterns in the superficial digital flexor ten-
new injury is not significantly different                                                    don core region of untrained horses. Aust Vet J
in non-surgically treated horses and in       Acknowledgments:                               1997;75:39-44.
                                                                                             13. Wilmink J. Wilson AM, Goodship AE.
horses undergoing superior check                This project was funded by the New          Functional significance of the morphology and
desmotomy. There was no significant           Zealand Equine Research Foundation.           micromechanics of collagen fibres in relation to
difference in the proportion of horses        Thanks to: Tim Aldridge of the New            partial rupture of the superficial digital flexor ten-
able to complete five or more races           Zealand Racing Conference, for pro-           don in racehorses. Res Vet Sci 1992:53:354-
after either treatment, neither was there     viding race records of Thoroughbred           14.Shoemaker RS, Bertone AL, Mohammad LN.
a significant difference in the time of       racehorses; D r Brian Anderson and            Arms SW. Desmotomy of the accessory ligament
recurrence between the two treatment          Professor Elwyn Firth, who examined           of the superficial digital flexor muscle in equine
                                                                                            cadaver limbs. Vet Surg 1991 ;20:245-252.
groups. T h e power of this study was         some of the horses included in this
                                                                                                        (An-eprrdjor publictition I M a y 1997)

Aust vet/ Vol75, No 9, September 1997                                                                                                        63 5

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