Orbital compartment syndrome resulting in unilateral blindness in two dogs

Patterns of bacterial culture and antimicrobial susceptibility test results for dogs with retrobulbar abscesses: 133 cases (2002-2019)

OBJECTIVE

To evaluate patterns of bacterial culture and antimicrobial susceptibility test results for dogs with retrobulbar abscesses and generate recommendations for empirical antimicrobial selection.

ANIMALS

133 dogs examined between 2002 and 2019.

PROCEDURES

Records were retrospectively reviewed to determine type of bacterial culture, number and type of bacterial isolates, antimicrobial susceptibility test results, concurrent and recent antimicrobial exposure, effect of culture results on antimicrobial regimen, and outcome.

RESULTS

Aerobic culture alone was performed in 37 dogs, and aerobic and anaerobic culture was performed in 96 dogs. Isolates were recovered from 96 dogs, with multiple isolates recovered from 54 (56%) of those dogs. Of the 69 dogs for which both aerobic and anaerobic culture was performed and at least 1 isolate was obtained, 34 (49%) had purely aerobic infections, 15 (22%) had mixed aerobic and anaerobic infections, and 20 (29%) had purely anaerobic infections. Pasteurella spp (n = 26), Streptococcus spp (20), and Escherichia coli (12) were the most common aerobic isolates. Bacteroides spp (n = 22), Actinomyces spp (10), and Fusobacterium (10) spp were the most common anaerobic isolates. Susceptibility test results led to changes in the antimicrobial regimen in 37 of 80 (46%) dogs. Of the 76 dogs for which outcome information was available, 78 (97%) recovered.

CLINICAL RELEVANCE

Multipathogen and anaerobic infections were common in dogs with retrobulbar abscesses. Susceptibility data supported the use of amoxicillin-clavulanate or a combination of clindamycin and enrofloxacin as first-line treatments. Additional study is needed to characterize anaerobic antimicrobial susceptibilities and to compare results of susceptibility testing with in vivo responses to antimicrobial administration.

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.).

Diagnosis and surgical management of a retrobulbar abscess causing unilateral exophthalmos in a Boer goat

A 10-year-old Boer goat wether presented for unilateral exophthalmos of 2- to 3-week duration. Ocular ultrasonography and computed tomography (CT) were utilized in the diagnosis of the patient's orbital disease and surgical planning. Exenteration was performed under the same general anesthetic event as CT. Cytology, culture, and histopathology were performed after exenteration. Cytology was consistent with a mixed bacterial infection. Culture confirmed the presence of Streptococcus ovis. Histopathology on the enucleated globe and mass revealed no evidence of tumor and confirmed intraocular extension of retrobulbar inflammation. Histopathologic diagnosis was consistent with severe chronic orbital pyogranuloma and fibrinosuppurative endophthalmitis confined to the subretinal space. The abscess recurred in the orbital space 2 weeks postoperatively; the orbit was explored. Repeat culture was consistent with S. ovis, Staphylococcus schleigeri subspecies coagulans, and Fusobacterium necrophorum. Complete resolution was obtained after drainage and lavage of the orbit. Abscess is cited as a cause of exophthalmos in small ruminants, but no individual case reports exist. Advanced imaging allowed presumptive diagnosis and surgical planning. Histopathology confirmed intraocular extension of retrobulbar disease.