Clinical presentation, treatment, and outcome of 24 dogs with bacterial meningitis or meningoencephalitis without empyema (2010‐2020)

Abstract

Background Bacterial meningitis (BM) and meningoencephalitis (BMEM) are associated with high case fatality rates and neurologic sequelae in people, but limited data exists on outcome in dogs. Hypothesis/Objectives To report the clinicopathologic features, treatment and outcome of BM/BMEM in dogs, with a focus on clinical presentation, relapse and long‐term neurological deficits. Animals Twenty‐four client‐owned dogs diagnosed with BM/BMEM without empyema. Methods Retrospective case series of dogs diagnosed with BM/BMEM from 5 veterinary referral hospitals between January 2010 and August 2020. Results Twenty‐four dogs were included. Median duration of clinical signs was 2 days (range ≤24 hours to 30 days) and signs recorded included pyrexia (3) and cervical hyperesthesia (10). Neurological deficits were present in 18 dogs including altered mentation (12), ataxia (8), nonambulatory status (8), head tilt (8), and cranial nerve deficits (13). Intracellular bacteria were visualized on cerebrospinal fluid (CSF) analysis in 15/24 dogs, with positive CSF bacteriological culture in 8/21. Otitis media/interna (OMI) was diagnosed in 15/24 dogs, of which 6/15 dogs underwent total ear canal ablation and lateral bulla osteotomy. Twenty dogs survived to hospital discharge. Median duration of antibiotic administrations was 8 weeks (range, 2‐16 weeks). Glucocorticoids were administered to 15 dogs. Median follow‐up time was 92 days (range, 10‐2233 days). Residual neurological deficits were reported in 9 dogs, with a single case of suspected relapse. Conclusions and Clinical Importance Clinical signs were variable in dogs with BM/BMEM, the nidus of bacterial infection was often OMI and the majority of dogs made a full recovery with treatment.

Diagnosis and surgical management of a type IVb dermoid sinus in a Cavalier King Charles Spaniel

“…Although, this requires more thorough investigations, it is not uncommon in dogs to have negative bacterial culture, with more severe neurological inflammatory conditions, such as intracranial empyema 33 or bacterial meningitis. 34 In the human literature, even in asymptomatic cases, aggressive treatment for complete resection of the dermoid sinus is advised to reduce chances of infection and development of neurological signs. 35 Based on the veterinary literature, surgical excision of a dermoid sinus, with the removal of the cystic lining, is considered curative with a good prognosis.…”

“…It is possible that similar pathophysiology induces the CSF inflammation of dogs with type IV dermoid sinuses. Although, this requires more thorough investigations, it is not uncommon in dogs to have negative bacterial culture, with more severe neurological inflammatory conditions, such as intracranial empyema 33 or bacterial meningitis 34 …”

Ventricular empyema in a dog diagnosed by magnetic resonance imaging and immediate postmortem cerebrospinal fluid culture

“…Pyrexia and neck pain are typically regarded as signs consistent with BM/BME in people; however, in a recent study only 13% of animals with BM/BME were pyrexic. 2 Vestibular dysfunction was commonly observed in these patients, 2 probably because otogenic causes of BM/BME are common in veterinary species.…”

“…2 The introduction of bacteria into the central nervous system (CNS) can occur via different routes including haematogenous spread, infiltration from adjacent structures, direct inoculation or migration of foreign bodies. 3 BM/BME is infrequently reported in dogs, with most cases secondary to intracranial extension of otitis media, 2 but there are also reports of BM/BME secondary to trauma, retrobulbar or intraoral extensions of infection, 4 and migration of plant foreign bodies. 5 In all these examples, bacteria are afforded access to the CNS directly or by infiltration from adjacent structures or migration of foreign bodies.…”

“…2 Long-term studies are lacking in veterinary literature, and while in dogs the outcome after prompt and aggressive medical or surgical treatment of otogenic intracranial infections is very good to excellent, 2 mortality in human BM patients is estimated at 14%-21%. 2,7 Treatment for BM/BME is centred around analgesia, antimicrobial therapy, treatment of seizures and intensive nursing, but specific protocols vary widely. Typically, animals are treated with multiple antibiotics, ideally based on culture and sensitivity, but the duration of treatment has been reported from as short as 2 weeks to as long as 16 weeks.…”