Exophthalmos associated with frontal sinus osteomyelitis in a puppy

Canine Retrobulbar Cellulitis and Abscessation in the Southeastern United States: A review of case management, diagnostic imaging, bacterial isolates, and susceptibility patterns

OBJECTIVE

To describe common bacterial organisms cultured from retrobulbar cellulitis and abscess lesions, in vitro susceptibility patterns, common diagnostic techniques utilized, etiologies encountered, and prevalence of blindness.

ANIMALS STUDIED

Thirty-eight dogs diagnosed with retrobulbar cellulitis or abscessation from 2007 to 2017.

PROCEDURE

For cases of orbital cellulitis or abscess, signalment, orbital imaging, cytology, histopathology, bacterial culture and susceptibility testing, presence of vision at the initial examination and resolution, and presumed cellulitis/abscess etiology were recorded.

RESULTS

Most cases were medically (78.9%) versus surgically managed (18.4%). Most common form of orbital imaging was computed tomography (48.5%) followed by ocular ultrasound (18.2%). Fifteen of eighteen cultures (83.3%) showed growth of aerobic bacterial organisms, anaerobic bacterial organisms, or both. Most common aerobic bacteria were gram-negative bacilli (40.0%) followed by Corynebacterium sp. (26.7%) and α-hemolytic Streptococci sp. (26.7%) but Micrococcus and Bacillus spp. were also identified. Most common anaerobic bacteria were gram-negative bacilli (40.0%). Antibiotics with highest susceptibility patterns included gentamicin, followed equally by amoxicillin/clavulanic acid, cephalothin, chloramphenicol, and imipenem. No bacteria were susceptible to cefovecin. Six cases presented with vision loss due to retrobulbar disease (15.8%). Idiopathic (50%) disease and tooth root abscessation (23.7%) were most commonly diagnosed cause of orbital disease.

CONCLUSION

Retrobulbar cellulitis/abscess is a serious and vision-threatening process, which can be effectively managed by broad-spectrum antibiotics such as gentamicin or amoxicillin/clavulanic acid, but not cefovecin. This study identified three organisms that have not been previously reported to be associated with orbital cellulitis (Corynebacterium sp., Bacillus sp. and Micrococcus sp.).

Management of Orbital Diseases

Orbital diseases are common in dogs and cats and can present on emergency due to the acute onset of many of these issues. The difficulty with diagnosis and therapy of orbital disease is that the location of the problem is not readily visible. The focus of this article is on recognizing classical clinical presentations of orbital disease, which are typically exophthalmos, strabismus, enophthalmos, proptosis, or intraconal swelling. After the orbital disease is confirmed, certain characteristics such as pain on opening the mouth, acute vs. chronic swelling, and involvement of nearby structures can be helpful in determining the underlying cause. Abscesses, cellulitis, sialoceles, neoplasia (primary or secondary), foreign bodies, and immune-mediated diseases can all lead to exophthalmos, but it can be difficult to determine the cause of disease without advanced diagnostic imaging, such as ultrasound, magnetic resonance imaging, or computed tomography scan. Fine-needle aspirates and biopsies of the retrobulbar space can also be performed.

Suspected sphenoid bone osteomyelitis causing visual impairment in two dogs and one cat

Objective  To present the clinical and magnetic resonance imaging (MRI) characteristics of sphenoid bone osteomyelitis.

Procedures  Two dogs (English Springer Spaniel – ESS, Golden Retriever – GR) and one cat (Domestic Long Haired) were presented with a 2–14‐day history of visual deficits and reduced pupillary light reflexes. Investigations included physical, ophthalmologic and neurological examination as well as hematology, serum biochemistry, MRI of the head and cerebrospinal fluid (CSF) analysis.

Results  MRI changes included thickening of the sphenoid bone and a loss of normal bone marrow signal on T1W MRI. Enhancement of the sphenoid bones, ventral meninges and ventral surface of the brain was present using paramagnetic contrast medium. CSF analysis was abnormal in the two dogs with increased cellularity, neutrophilic pleocytosis, intracellular bacteria and increased total protein in one, and with lymphocytic pleocytosis in another. CSF analysis was normal in the cat.

An underlying cause for the osteomyelitis could not be identified. The use of broad‐spectrum antibiotics for 3–6 weeks combined with anti‐inflammatory medications proved effective. Full clinical recovery occurred with no relapse during the follow up time of 7 (ESS) and 4 (Domestic Long Haired) years. The GR relapsed 10 months after treatment and recovered following a second 3‐week course of broad‐spectrum antibiotics with no relapse during the following 3 years.

Conclusion  Visual pathway deficits in dogs and cats may be due to sphenoid bone osteomyelitis. MRI and CSF analysis can assist diagnosing this potentially treatable condition. To the authors’ knowledge this is the first report of sphenoid bone osteomyelitis in these species.

Orbital inflammatory disease and pseudotumor in dogs and cats

Orbital disease is common in dogs and cats. Clinical signs include exophthalmos, protrusion of the third eyelid, and resistance to retropulsion of the globe. This article discusses diagnostic work-up for dogs and cats with signs suggestive of orbital disease. Diagnosis and treatment of nonneoplastic orbital diseases follows. Congenital diseases are discussed first, followed by inflammatory diseases of the orbit including orbital pseudotumor. Lastly, other less common orbital conditions are addressed.

Taenia coenurus in the orbit of a chinchilla

A 4-year old, male intact, captive-bred chinchilla (Chinchilla lanigera) was presented due to progressive exophthalmos of the right eye over a 5-month period. Ophthalmic examination revealed exophthalmos with dorsal displacement of the right globe. Retropulsion was decreased and a fluctuant, subcutaneous mass could be palpated posterior and dorsal to the central aspect of the zygomatic bone. Transdermal ultrasonography revealed a fluid-filled mass consistent with a cyst located within the ventral right orbit. Computed tomography demonstrated dorsal displacement of the globe, lateral displacement of the zygomatic arch, and numerous mineral-dense foci within the lumen of the cyst. The cyst was removed en bloc by ventral transpalpebral orbitotomy. Histopathology revealed a single capsulated cyst with multiple invaginated protoscolices, characterized by a prominent scolex with refractile hooklets, suckers, and abundant calcareous corpuscles consistent with a Taenia coenurus. Exophthalmos resolved with surgical therapy and there was no evidence of recurrence or postoperative complications over a period of 2 years. To the authors' knowledge, this is the first reported case of an orbital cyst of parasitic origin in a chinchilla.

Orbital cellulitis associated with Toxocara canis in a dog

Reports of Toxocara canis ocular larva migrans are uncommon in animals, with only a few cases reported. Most reports involve larval migration into the retina and choroid, with parasitic invasion of the orbit reported only in experimental studies. This is the first clinical case of Toxocara canis infection in the retrobulbar region of a 10-year-old, cross-bred male dog presenting with unilateral orbital cellulitis. Ophthalmic signs included protrusion of the nictitating membrane, chemosis, exophthalmos and hypertropia. The parasite was diagnosed by histologic and parasitologic examination of orbital tissues, which were removed during enucleation.

Anterior chamber to frontal sinus shunt for the diversion of aqueous humor: a pilot study in four normal dogs

Silicone tubing was used to divert aqueous humor from the anterior chamber of the right eye to the rostral compartment of the right frontal sinus in four clinically normal mixed-breed dogs. Biomicroscopic examination, and pneumoapplanation tonometry and tonography, completed for up to 18 weeks postoperatively, confirmed gonioimplant function in all four cases. The dogs were euthanized at 6, 8, 16 and 18 weeks postoperatively. Gonioimplant patency was further confirmed by postmortem examination of the globes, implants and frontal sinuses. Gross and light microscopic examinations revealed iridal attachments to the implant (n = 4), mild anterior uveitis (n = 3), anterior subcapsular cataracts (n = 4), and focal corneal (n = 3) and scleral (n = 3) scarring in the operated globes. Light microscopic examination of frontal sinus specimens revealed mild lymphocytic proliferation and fibrosis immediately adjacent to the implant entrance site. There were no bacteria detected on aerobic or anaerobic cultures of the frontal sinuses or light microscopic examination of the globes or frontal sinuses. Results indicate that the frontal sinus shunting of aqueous humor is a safe and effective means of extraorbital aqueous diversion with potential applicability in the management of glaucoma.

Orbital neurofibrosarcoma in a dog

A young dog was presented with rapidly progressive, unilateral, exophthalmos. Ultrasound-guided fine-needle aspiration of the retrobulbar mass resulted in a diagnosis of fibrosarcoma. Magnetic resonance imagery revealed tumor invasion into the brain, and palliative therapy was elected. The dog was euthanized 4 weeks following diagnosis due to progressive neurological signs. The final diagnosis was neurofibrosarcoma involving the pons, brainstem, left orbit and left trigeminal nerve.

Pediatric ocular emergencies

There are few ocular emergencies that are unique to the pediatric patient. Most ocular emergencies are traumatic in origin, and the prognosis is often determined by the extent of the injury. Some congenital anomalies that may present as ocular emergencies are also discussed. The focus of this article is recognition and initial therapy for the more common pediatric ocular emergencies.