Discussion

Wray, H., Elliott, J., Bailey, S.R., Harris, P.A. and Menzies-Gow, N.J.
Royal Veterinary College, Hawkshead Lane, North Mymms,
Herts. AL9 7TA, UK; University of Melbourne, Australia; and
Equine Studies Group, WALTHAM Centre for Pet Nutrition
Leics. LE14 4RT, UK. Email: nmenziesgow@rvc.ac.uk
Aims: To determine whether exercise affects the concentrations
of inflammatory markers in normal and laminitis-prone ponies.
Methods: The short (1 day) and longer term (14 days) effects of
low intensity (10 min walking and 5 min trotting) exercise on
plasma concentrations of inflammatory markers in normal (NL) and
laminitis-prone (LP) nonexercised ponies (n = 6/group) was
determined. Plasma TNF, serum amyloid A (SAA) and
haptoglobin concentrations were measured using ELISAs,
fibrinogen concentrations were determined by heat precipitation
and plasma adiponectin and insulin concentrations were measured
using radioimmunoassays. Multivariate analysis was undertaken
to determine what factors were independently associated with
each cytokine. Results: Pre-exercise, plasma [adiponectin] was
significantly (P = 0.0001) lower in LP (2.4 ± 0.1 ng/l) compared to
NL (4.03 ± 0.2 ng/l), but exercise had no effect. Exercise had no
effect on plasma [TNF-±] or [fibrinogen] in either group. Following
short-term exercise, all ponies had an initial decrease in serum
[insulin] immediately after exercise, followed by a large increase
peaking 10 min after the cessation of exercise, before returning
to pre-exercise values. On Day 14 these fluctuations were
significantly (P = 0.001) reduced. SAA concentrations in all ponies
were significantly (P = 0.00001) reduced after long-term exercise
compared to Day 1 values. Plasma [haptoglobin] were significantly
(P = 0.00001) higher in PL compared to NL on Day 1. This
difference was no longer apparent after longer term exercise, such
that the [haptoglobin] in PL had decreased to concentrations
similar to those in NL. Conclusions and practical significance:
Long-term low intensity exercise significantly decreased [SAA] in
all ponies and plasma [haptoglobin] in LP such that it was no
longer increased compared to NP. Thus, regular low intensity
exercise is sufficient to have an anti-inflammatory effect, which is
greater in LP, and so may be beneficial in preventing this putative
risk factor in pasture-associated laminitis. Acknowledgements:
This study was funded by the Laminitis Trust.