Page 1134 - Equine Clinical Medicine, Surgery and Reproduction, 2nd Edition

Nervous system 1109

VetBooks.ir The facial, trigeminal and vestibulocochlear nerves Diagnosis
Polyneuritis equi is often diagnosed after excluding
are most commonly affected.
Aetiology/pathophysiology other possible causes. Haematology and CSF cytol-
ogy are usually unremarkable. Mild increases in
Polyneuritis equi is considered to be a disease of protein and leucocytes may be present in the CSF.
the adult horse and is thought to involve an autoim- Antimyelin antibodies can be detected in CSF; how-
mune response against the myelin of the cranial and ever, the usefulness of this test is debatable. A muscle
sacrococcygeal extradural nerve roots. Prior bacte- biopsy from the sacrocaudalis dorsalis lateralis mus-
rial and viral infections have been implicated in this cle can easily be performed under standing sedation
response. and may reveal the presence of marked inflamma-
tory cell infiltration around nerve terminals and is
Clinical presentation currently the ante-mortem diagnostic test of choice.
The neurological deficits primarily reflect LMN defi-
cits at the level of the cauda equina and most notably Management
include obstipation and urinary incontinence. The There is no specific treatment. Supportive ther-
tail hangs limply without tone (Fig. 10.61), and the apy may include manual evacuation of the rectum,
anal sphincter (Fig. 10.62), rectum, bladder, urethral provision of a soft diet and urinary bladder decom-
sphincter and vulva or penis are paralysed. There is pression. Corticosteroids (dexamethasone [0.05–
usually an insidious onset, with progression over sev- 0.2 mg/kg q24 h] or prednisolone [1 mg/kg p/o
eral weeks. The condition is usually progressive, but q12 h]) are commonly used. Affected horses should
signs may remain static after attaining a certain level be monitored closely for complications such as intes-
of severity. CN signs are not always present, but when tinal tract impactions, oesophageal obstruction
they are they help to distinguish this disease from and urinary tract infections. Antimicrobial therapy
other conditions that result in damage to the struc- may be required to treat secondary urinary tract
tures of the cauda equine, such as sacral trauma. infections.

Differential diagnosis Prognosis
EHV encephalomyelitis, arboviral encephalitis, rabies, The prognosis is poor because this is a progressive
EPM, trauma and EMND should be considered. disease that rarely responds to treatment.

10.61 10.62

Fig. 10.61 Poor tail tone secondary to polyneuritis Fig. 10.62 Poor anal tone secondary to polyneuritis
equi. equi.