Meningitis and Meningoencephalitis
Frequently asked questions about Meningitis and Meningoencephalitis in dogs and cats
Meningitis and meningoencephalitis are inflammatory processes of meninges and of the meninges and brain tissue, respectively. Inflammatory pathologies of the central nervous system are frequent in veterinary clinical practice, but countless features of these diseases are still under study.
Both diseases are more frequent in young dogs and cats and some dog breeds are more predisposed than others, such as the Chihuahua, Pug, French Bulldog and Maltese.
What are the causes?
Meningitis and meningoencephalitis can be divided into two large groups, infective and non-infective origins. Infective meningitis/meningoencephalitis may be secondary to a virus, bacteria, protozoa or parasites. Non-infective meningitis/meningoencephalitis is a series of inflammatory processes with an unknown cause, probably of immune-mediated origin.
Are meningitis and meningoencephalitis contagious for people or other animals?
When the cause of an inflammatory process is an infectious agent such as a virus, the disease rarely can infect animals of the same species but isn’t contagious to humans even in cases of close contact with the pet. Autoimmune meningitis and meningoencephalitis are not contagious either for animals or for people.
What are the clinical signs of these diseases?
Meningoencephalitis typically has an acute or sub-acute onset and progressive course, however, a subtle onset or a fluctuating symptomatology is possible. Recurrent clinical signs are cervical pain, encephalic signs such as disorientation and seizures. Sometimes systemic clinical signs such as fever and dysorexia may be present. Meningitis causes the same clinical signs, except those of encephalic nature.
How can meningitis/meningoencephalitis be diagnosed?
Meningitis and meningoencephalitis can be diagnosed by magnetic resonance imaging (MRI, Figure 1) and cerebrospinal fluid exams (Figure 2). Diagnostic procedures must sometimes be completed with specific tests, in order to exclude infectious diseases.
Figure 1. Magnetic resonance imaging (MRI) in a 3-year-old Chihuahua with non-infectious meningoencephalitis. Multifocal inflammatory areas of brain are seen.
Can meningitis/meningoencephalitis be treated?
In dogs and cats in which an infective cause (virus, bacteria, fungus, protozoa) is identified, a specific therapy against the microorganism can be performed. Pets affected by infective meningitis/meningoencephalitis have a guarded prognosis and recovery is challenging. Treatment of the non-infectious form is based on the use of drugs that modulate or reduce the immune system activity; however, even in these cases the prognosis is not always favorable. Treatments often have to be protracted for long times and about 30% of dogs do not respond satisfactorily to administered drugs. Moreover, affected pets can decline neurologically in a short period of time. However, some affected dogs and cats can successfully recover with complete remission of neurological clinical signs.
Figure 2. Cefalorachidian fluid collection from cisterna magna, performed at the end of MRI procedures