Page 1065 - Equine Clinical Medicine, Surgery and Reproduction, 2nd Edition

1040 CHAPTER 9

VetBooks.ir SPLENIC NEOPLASIA 9.44

Definition/overview
Splenic neoplasia may be primary or secondary. It is
uncommon in the horse.

Aetiology/pathophysiology
Splenic lymphoma is most common, although mela-
noma and haemangiosarcoma have also been reported.
Lymphoma can occur in horses of any age but is more
common in horses 2–8 years of age. Splenic tumours
may be primary or secondary (metastatic).

Clinical presentation
Weight loss, intermittent colic, depression and
anorexia may be the initial signs. If splenic neoplasia Fig. 9.44 Transabdominal ultrasound image of
is secondary, clinical signs relating to the location of a splenic lymphoma. Note the large splenic mass
the primary tumour may be present. delineated by the caliper marks.

Differential diagnosis
The vague clinical signs mean that a number of other If splenic neoplasia is suspected, a thorough diag-
diseases must be considered. If a splenic abnormal- nostic work-up should be considered to identify the
ity can be visualised or palpated, splenic abscess or primary location (if present) and determine whether
splenic haematoma should be considered. additional metastatic lesions exist.

Diagnosis Management
Hypoproteinaemia is common but non-specific. By the time splenic neoplasia is diagnosed, advanced
Serum IgM may be low, but this is an inconsistent disease is usually present. Tumours are usually pres-
finding. AID or IMHA may be present. An irregular ent in other locations and therefore splenectomy is
or enlarged spleen may be palpable p/r. The spleen rarely a viable option. If a solitary tumour with no
can be visualised ultrasonographically over the cau- evidence of metastasis, primary disease or signifi-
dal left abdomen. Depending on the type of neopla- cant abdominal adhesions is identified, splenectomy
sia, increased echogenicity, abnormal shape or the could be considered. Chemotherapeutic agents have
presence of focal masses may be evident (Fig. 9.44). not been adequately evaluated and are cost prohibi-
Abdominocentesis should be performed, but it is tive in most situations. Dexamethasone (40 mg i/m
uncommon to identify neoplastic cells cytologically q4 days for 4 weeks, tapered over time) has been used
due to poor exfoliation. A fine-needle aspirate may be with anecdotal success for short-term palliation in
diagnostic. Ultrasonographic guidance is preferred splenic lymphoma.
because of the high vascularity of the spleen and
the potential for focal or multifocal lesions. Splenic Prognosis
biopsy can be performed but presents a higher risk The prognosis for splenic neoplasia is grave. A diag-
for haemorrhage. Laparoscopy can also be used to nosis is often not made until late in the disease and
visualise the spleen and obtain diagnostic samples. treatment is usually unrewarding.