Presumed optic neuritis of non‐infectious origin in dogs treated with immunosuppressive medication: 28 dogs (2000‐2015)

Abstract

To describe the clinical findings, magnetic resonance imaging features, management and outcome of canine cases with presumed optic neuritis of non-infectious origin that were presented to a UK referral centre from January 2000 to December 2015. Materials and MethOds: The clinical database was searched for optic neuritis. Dogs with acute-onset vision impairment, systemic immunosuppressive treatment and follow-up of ≥6 months were included. Information collected included: age; gender; breed; clinical signs and duration; physical, ophthalmic and neurological examination findings; concurrent systemic disease; and results of electroretinogram, magnetic resonance imaging, cerebrospinal fluid analysis, polymerase chain reaction and serology testing for Toxoplasma gondii, Neospora caninum and canine distemper virus, haematology and serum biochemistry profiles, abdominal ultrasound, thoracic radiography, treatment and outcome. results: Twenty-eight dogs were included, with a total of 48 affected optic nerves. Age at presentation ranged from 6 months to 10.5 years. Fundoscopic evidence of optic nerve disease was present in 34 of 48 (71%) optic nerves. Magnetic resonance imaging revealed enlargement of 32 of 48 (67%) nerves and contrast enhancement of 28 of 48 (58%) nerves. Cerebrospinal fluid analysis performed in 25 of 28 (89%) dogs revealed pleocytosis (>5 nucleated cells/uL) in 11 of 25 (44%) and increased protein (>0.35 g/L) in 11 of 25 (44%). Immunosuppressive prednisolone was administered to all dogs. Prednisolone was used alone in 9 of 28 (32%) dogs; the remaining 19 dogs received a combination of prednisolone with cytosine arabinoside, cyclosporine and/or azathioprine. Vision was recovered in 24 eyes (50%) of 18 affected dogs. clinical significance: A positive response to treatment was observed in 64% of dogs with presumptively diagnosed optic neuritis treated with immunosuppressive medication.

Pharmacokinetics of a cytosine arabinoside subcutaneous protocol in dogs with meningoencephalomyelitis of unknown aetiology

“…It is S‐phase specific and causes competitive inhibition of DNA polymerase in mitotically active cells, thus preventing DNA replication, halting the cell cycle and precipitating apoptosis (Gmeiner et al., 2003; Scott‐Moncrief et al., 1991; Withrow et al., 2012). It has therefore been used for the treatment of multiple disease processes involving pathologic cell replication, including lymphoma (involving the bone marrow or central nervous system and in cases of relapse), leukaemia and optic neuritis of non‐infectious origin (Gillem et al., 2015; Marconato et al., 2008; LaRue et al., 2018; Pawlak et al., 2014, 2016; Bedos et al., 2020; Alvarez et al., 2006). As MUE is highly suspected to be due to a robust T‐cell autoimmune response, CA has been utilized as a treatment option for meningoencephalomyelitis of unknown aetiology (MUE) with the goal of inhibiting the pathologic lymphocyte proliferation associated with this autoimmune disease (Vitale et al., 2019).…”

“…It is S-phase specific and causes competitive inhibition of DNA polymerase in mitotically active cells, thus preventing DNA replication, halting the cell cycle and precipitating apoptosis (Gmeiner et al, 2003;Scott-Moncrief et al, 1991;Withrow et al, 2012). It has therefore been used for the treatment of multiple disease processes involving pathologic cell replication, including lymphoma (involving the bone marrow or central nervous system and in cases of relapse), leukaemia and optic neuritis of non-infectious origin (Gillem et al, 2015;Marconato et al, 2008;LaRue et al, 2018;Pawlak et al, 2014Pawlak et al, , 2016Bedos et al, 2020;Alvarez et al, 2006).…”

Unilateral blindness associated with steroid‐responsive meningitis arteritis in a 9‐month‐old Beagle

“…Typical MRI features of optic neuritis include enlargement and contrast enhancement of the optic nerve, which were not seen in this patient. 9,10 Although MRIs of the optic nerves have been reported to be normal in 7-19% of dogs with optic neuritis, none of the dogs in these studies exhibited the classical symptoms of SRMA. 9,11 Optic neuritis can also represent a disseminated or isolated form of MUO, more specifically granulomatous meningoencephalitis, yet the latter presents typically with a mononuclear pleocytosis on CSF analysis and visible parenchymal changes on MRI, which was not the case in this Beagle.…”

“…9,10 Although MRIs of the optic nerves have been reported to be normal in 7-19% of dogs with optic neuritis, none of the dogs in these studies exhibited the classical symptoms of SRMA. 9,11 Optic neuritis can also represent a disseminated or isolated form of MUO, more specifically granulomatous meningoencephalitis, yet the latter presents typically with a mononuclear pleocytosis on CSF analysis and visible parenchymal changes on MRI, which was not the case in this Beagle. Elevated serum CRP levels as seen in this Beagle are a classical finding in dogs presenting with SRMA, whereas these are generally normal in cases with MUO.…”