The case records of 23 horses and one donkey affected by hypertrophic
osteopathy (HO) (Marie's disease) were reviewed. All affected animals
presented with limb swellings, which were bilaterally symmetrical and
usually involved both fore- and hindlimbs. Associated signs included s
tiffness/lameness and weight loss. Radiological features included peri
osteal new bone formation over the diaphyses and metaphyses of affecte
d bones. The metacarpal and metatarsal bones were most frequently affe
cted. Articular surfaces remained free of disease. Seventeen animals w
ere destroyed on humane grounds, 3 horses recovered after successful t
reatment of the primary disease, 3 horses recovered after symptomatic
treatment and one horse was lost to follow-up. Significant primary dis
eases that were believed to predispose to HO were identified (pre- or
post mortem) in 14 cases. In each of these cases, an intrathoracic dis
ease was identified, although co existing extrathoracic disease was pr
esent in 3 cases. Granulomatous inflammatory lesions were present in 9
of these 14 cases. In 4 horses, which underwent necropsy examination,
no significant underlying disease was identified.