Page 831 - Clinical Small Animal Internal Medicine

73 Meningoencephalitis and Meningomyelitis 799

meningoencephalitis, although advances in stereotactic Therapy
VetBooks.ir biopsy systems and minimally invasive methods may Therapy for meningoencephalitis and meningomyelitis
help in making such an option more acceptable to both
clinicians and the owners of affected animals. As GME,
NME, and NLE are diagnoses that can only be made with depends on the underlying etiology causing the inflam-
mation, but typically involves antimicrobial, antiinflam-
histopathology, many clinicians will refer to cases of matory or immunosuppressive medications. There are
inflammatory CNS disease diagnosed with imaging and no antiviral medications known to be effective or cur-
CSF analysis as meningoencephalitis of unknown etiology rently recommended for use in small animals with CNS
(MUE) or unknown origin (MUO). This designation viral infections, and treatment for these patients remains
typically does not include dogs with SRMA, eosinophilic largely supportive. Animals with a documented or sus-
meningoencephalitis, or greyhound meningoencephali- pected bacterial meningoencephalitis are ideally treated
tis as these patients have distinctive signalments, clinical with an antibiotic that shows good penetration of the
syndromes, imaging findings, and/or CSF abnormalities blood–brain and blood–CSF barriers (Table 73.3).
(see Table 73.2). Antifungal medications are indicated in some patients,
A variety of assays are available to identify infectious and these also vary in their ability to penetrate the CNS.
agents within the blood, CSF or other body fluids. These Doxycycline not only has antibacterial activity with
include assays for organism antigens (e.g., Cryptococcus good CNS penetration, but also is the drug of choice for
neoformans), antibodies generated against the organism animals with rickettsial infections. Animals with T. gondii
(e.g., IgG and IgM for canine distemper or Toxoplasma or N. caninum infections may respond to sulfa antibi-
gondii), and polymerase chain reaction (PCR) for organ- otics, clindamycin and/or pyrimethamine. Animals with
ism DNA or RNA. Cytologic findings associated with infectious meningoencephalitis often benefit from
other body systems (e.g., inclusion bodies in cells from a short‐term, antiinflammatory doses of glucocorticoids,
conjunctival swab in animals with canine distemper) although immunosuppressive doses and prolonged
may also aid in the diagnosis of certain infectious administration of these medications should be avoided
diseases and prompt additional testing for suspected as they can impair clearance of the infecting organisms
organisms. and substantially worsen clinical signs.

Table 73.3 Antimicrobial medications for meningoencephalitis and meningomyelitis

Medication Dosing Indications Additional considerations
Potentiated sulfonamides 15 mg/kg q12h Bacterial meningitis, protozoal Consider concurrent folate
(e.g., trimethoprim/sulfa) disease of central nervous supplementation
system (CNS)
Clindamycin 5–25 mg/kg q12h Bacterial meningitis, protozoal Penetration of CNS controversial
disease of CNS
Doxycycline 5–10 mg/kg q12–24h Bacterial or rickettsial disease of
CNS
Third‐generation Variable Bacterial meningitis
cephalosporins
Chloramphenicol 25–50 mg/kg q8h (dog) or Bacterial meningitis Concurrent use with phenobarbital
12–25 mg/kg q12h (cat) not recommended
Fluoroquinolones 5–15 mg/kg q12h Bacterial meningitis Penetration of CNS controversial
(enrofloxacin, ciprofloxacin) (ciprofloxacin) Avoid higher doses in cats due to
2.5–10 mg/kg q12h retinal toxicity
(enrofloxacin)
Metronidazole 10–15 mg/kg q12h Bacterial meningitis (anaerobic) CNS toxicity possible at higher doses
Meropenem 25 mg/kg IV q8h Bacterial meningitis Doses up to 40 mg/kg q8h have been
suggested but not tested in veterinary
patients
Fluconazole 2.5–10 mg/kg q12–24h Fungal infections
Pyrimethamine 0.5–1 mg/kg q24h Protozoal infections