Page 1319 - Problem-Based Feline Medicine

64 – THE CAT WITH ABNORMAL GLOBE POSITION OR SIZE 1311

Imaging techniques which are useful include:
ORBITAL NEOPLASIA***
● Ultrasound: anechoic or hypo-echoic regions are
suggestive of a fluid-filled cavity while complex
Classical signs
echogenicity is more suggestive of cellulitis.
● Plain radiographs of the maxilla and zygomatic ● Usually slow in onset over weeks to
arch may demonstrate signs suggestive of osteo- months. Lymphosarcoma of the orbit can
myelitis such as proliferation or lysis of bone. however progress more rapidly.
A frontal sinus view may be helpful. ● Not usually associated with pain on opening
● Dental radiography might demonstrate a rarified area the mouth except in advanced stages.
of alveolar bone around the tooth root apical region. ● Exophthalmos with a prominent nictitating
● CT or MRI in special circumstances might be help- membrane.
ful for demonstrating soft tissue detail.
Laboratory examination of aspirates or swabs of orbital
Pathogenesis
contents are valuable. Look for neutrophils, macrophages,
signs of bacterial lysis. Lymphosarcoma can localize in the orbit in multicen-
tric disease, and is often bilateral when it involves the
orbit.
Differential diagnosis Squamous cell carcinoma invades from the oral
mucous membrane, the nasal cavity or from the frontal
Orbital neoplasia usually causes more slowly progres-
sinus into the medial orbit.
sive onset of signs with less acute pain.
Fibrosarcoma is a primary neoplastic disease originat-
ing from the periosteum of the bone surrounding orbit.
Treatment
Treatment involves careful surgical drainage via a small Clinical signs
incision caudal to upper molar tooth. Blunt probes are
Clinical signs are usually slow in onset over weeks to
preferable to hemostats, which cause more trauma to
months. Lymphosarcoma of the orbit can however
orbital tissue.
progress more rapidly.
Use oral antibiotics based on culture and sensitivity
Exophthalmos is present and the severity is dependent
of aspirates, or treat empirically with antibiotics
on the degree of proliferation of the neoplasm.
directed particularly at anaerobes, such as clindamycin
(5.5 mg/kg q 12 h). Administer for 7–10 days, but for A prominent nictitating membrane might be seen
severe infections use for up to 28 days. especially in the later stages.
Anti-inflammatory drugs help to reduce inflammation Chemosis of the conjunctiva occurs with subsequent
and achieve more rapid reduction of peri-orbital exposure and drying.
swelling.
Bulging of oral mucosa caudal to the upper M1 tooth is
● Oral prednisolone 1 mg/kg q 24 h for the first
occasionally seen, especially in the later stages of the
7 days or
disease.
● NSAIDs.
– Ketoprofen: Ketofen 2 mg/kg SC continuing Pain on opening mouth is variable, and the major-
1 mg/kg orally q 24 hourly for up to 5 days. ity of cases do not show signs of pain. Neoplastic
– Carprofen: Rimadyl 4 mg/kg SC or IV. Oral dose disease may become more painful if the affected tis-
not approved for use in cats. sue becomes inflamed. If pain does occur, it is more
– Meloxicam: Metacam 0.1 mg/kg (one drop/kg) likely to occur in the later stages of the disease, when
PO as an initial loading dose then 1–2 drops q 24 there is more gross disruption of normal tissue archi-
hourly for up to 3 days. tecture.