Vet360 Vol 3 Issue 04 August 2016 - Page 28

OPTHALMOLOGY • • secondary rupture of the proximal nasolacrimal duct in cases of dacrocystorhinitis. foreign bodies from the oral cavity or those penetrating the orbital adnexa or conjunctiva. Clinical signs. • • • • • • • Figure 2: Traumatic proptosis in a Pekingese dog. During the examination of the patient special emphasis should be placed on examination of the orbital margins. Fractures of the nasal and frontal sinuses can cause leakage of air causing orbital emphysema and exophthalmos. Radiology and ocular ultrasonography are valuable diagnostic tools for this form of exophthalmosis. • • Acute, usually unilateral, exophthalmos. Protrusion and congestion of the third eyelid. Decreased globe mobility. Serous to mucopurulent ocular discharge. Periocular pain. Severe pain on opening the mouth. Lethargy and fever are common and assist in indicating an inflammatory cause. An inflammatory leukogram may also be present. A normotensive globe. The classic history is an acute onset of signs and reluctance to eat. Ocular ultrasonography is a cost effective method to differentiate cellulitis from a drainable retrobulbar abcess and to determine the presence of a foreign body. Treatment: Treatment: One should approach patients with orbital trauma with the following principles: • Prevent additional swelling and haemorrhage. • Prevent exposure of the cornea and conjunctiva. • Prevent orbital infection. Broadspectrum systemic antibiotics [amoxicillin and clavulanic acid] as well as systemic non steroidal inflammatory drugs should be used. Topical ophthalmic lubricants should be used to protect the cornea from exposure keratitis. These principles can be implemented by: • keeping the animal confined and quiet. • using analgesics or tranquilizers if indicated. • applying cold packs to the orbital region. • performing a temporary tarsorrhaphy. • parenteral corticosteroids. • broad spectrum antibiotics. Orbital abcesses may require drainage of the orbital space into the mouth.This is done by incising only the buccal mucosa directly behind the last molar on the affected side with a scalpel blade and then placing a curved haemostat into the hole and gently pushing it up into the retrobulbar region and opening the forceps points. Exudate should drain from the oral wound. Remove the haemostat whilst keeping the points open. By opening and closing the jaw more exudate can be “pumped” out of the wound. Systemic hyperosmotic agents and nonsteroidal antiinflammatory drugs should not be used. The latter can be used once haemorrhage or severe bruising has stabilised. 3. Inflammatory exophthalmos Inflammatory orbital disease can be caused by bacteria, fungi, parasites and non infectious causes such as eosinophilic myositis. The process usually begins as orbital cellulitis, which localises and, at a later stage, organises to form an abscess. Agents causing inflammation may gain entrance to the orbit via; • the haematogenous route. • wounds due to external cranial trauma. • penetrating wounds from the oral cavity into the retrobulbar space. • infection in the adjacent paranasal sinuses and nasal cavity. • sialoadenitis or abcesses of the zygomatic salivary gland. 4. Eosinophilic myositis This is an inflammatory disease of unknown cause. An autoimmune aetiology is suspected as autoantibodies to the 2M muscle myofibres of the muscles of ma