Initial treatment
Initial treatment consisted of surgical excision of the osteosarcoma
under general anaesthesia and local injection of carboplatin eleven
weeks after surgery. For the surgery, the horse was positioned in left
lateral recumbency and an Esmarch tourniquet was placed proximal to the
carpus. After surgical preparation and draping, an elliptical incision
was made around the tumour and the central part of the skin (3 cm wide)
was removed. The incision was extended 4 cm proximal and distal of the
tumour. Soft tissues were dissected distally and proximally of the mass
until the level of the bone. With a periosteal elevator the mass was
separated from the underlying bone cortex and removed. At the
palmaromedial aspect of the third metacarpal bone and the dorsal aspect
of the second metacarpal bone, a depression filled with soft bone-like
tissue was present. This was excised and a sample was taken for
histopathology. The remaining irregular bone was curetted, resulting in
a crater of approximately 5 cm long, 1 cm width and 1 cm deep. The bone
and soft tissues were flushed and a Penrose drain was inserted from the
crater towards a stab incision distal to the initial incision. The
subcutaneous tissue and skin were sutured in a simple continuous
pattern, and the wound was covered with an antimicrobial, non-adhesive
dressing (Zorbopad1), secured with cotton and an
elastic bandage. During the recovery from anaesthesia, radial paralysis
of the contralateral front limb was noted. A medical treatment
consisting of both local (Ekyflogyl2) (topical gel
containing 1.8 mg/ml prednisolone, 8.7 mg/ml lidocaine and 968 mg/ml
DMSO applied topically b.i.d. during seven days) and systemic (0.01
mg/kg btw dexamethasone, i.v., q. 24 h during three days) steroidal
anti-inflammatory drugs was initiated. The paralysis gradually improved
in the hours following surgery and full resolution was obtained after
one week.