Bacterial meningitis and subdural empyema caused by Actinomyces canis in a dog

Retrospective evaluation of the clinical presentation, magnetic resonance imaging findings, and outcome of dogs diagnosed with intracranial empyema (2008-2015): 9 cases

OBJECTIVE

To describe the clinical presentation, advanced imaging findings, and short- and long-term outcomes in dogs with intracranial empyema.

DESIGN

Retrospective case series.

ANIMALS

Client-owned dogs diagnosed with intracranial empyema.

METHODS

Medical records from 2 referral hospitals were searched for dogs diagnosed with intracranial empyema. To be included in this study, dogs had to fulfill 1 or more of the following 3 inclusion criteria: a magnetic resonance imaging (MRI) scan with space occupying accumulation of extra-axial material suggestive of empyema, a cerebrospinal fluid analysis suggestive of empyema, or direct visualization of purulent material during intracranial surgery.

RESULTS

Nine dogs with intracranial empyema were included, with a median age of 3.5 years (range: 4 mo-12.5 y). All presented as emergencies with 7 of the 9 dogs showing neurological abnormalities and 2 of the 9 with retrobulbar swelling and exophthalmos. Six had surgical intervention, 1 was medically managed, and the remaining 2 dogs were euthanized. Typical MRI findings included extra-axial, T1-weighted hypo- to isointense, T2-weighted hyperintense material compared to gray matter with varying degrees of contrast enhancement, with 6 of 8 showing evidence of contiguous infection from adjacent structures on MRI. For 7 dogs, ≥1 samples were sent for culture and sensitivity, with Enterococcus (surgical swab), Streptococcus pneumonia (from cerebral spinal fluid), and coagulase positive Staphylococcus (ear swab) being cultured. The median antimicrobial course length was 6 weeks (range: 2-28 wk). All dogs for which treatment was attempted survived to discharge, with a median hospitalization time of 7 days (range: 4-10 d). Four of the 7 are still alive at the time of writing (1 lost to follow-up; 2 euthanized for other reasons) with all 4 considered neurologically normal with a successful long-term outcome.

CONCLUSION

Although intracranial empyema in dogs is a rare condition, excellent outcomes are possible in those cases treated appropriately.

Successful treatment of mitral valve endocarditis in a dog associated with 'Actinomyces canis-like' infection

Infective endocarditis, an inflammation of the endocardial surface due to invasion by an infectious agent, is more common in middle sized to large breed dogs. We herein report a case of mitral valve endocarditis in a 9-year-old male-castrated Weimaraner caused by an Actinomyces canis-like bacterium, not previously reported in association with infection in dogs.