Fungal Infections of the Central Nervous System in the Dog and Cat

Clinicopathological and diagnostic imaging findings in a dog with neurocandidiasis

Neurocandidiasis is systemic candidiasis with central nervous system involvement. This case report describes the clinical presentation, diagnostic test results, and histopathology of a dog with neurocandidiasis. A 3-year-old German shepherd dog was presented for a 3-day history of abnormal mentation, neck pain, and ataxia. Magnetic resonance imaging (MRI) scan of the brain revealed multifocal, small, round, intra-axial lesions within the forebrain. Examination of the cerebrospinal fluid revealed severe neutrophilic inflammation. Extensive testing for infectious diseases was negative. The dog was administered immunosuppressive doses of corticosteroids. The dog's clinical signs improved transiently but got worse 12 days after starting the treatment. Repeat MRI scan revealed multiple, intra-axial, target-like nodular lesions scattered throughout the brain parenchyma. In the temporal muscles, nodules were seen. Cytology of the fine needle aspirates of the nodules in the temporal muscles revealed a neutrophilic inflammation with hyalohyphomycosis. Postmortem examination was compatible with a severe systemic fungal infection. Candida albicans was isolated from the brain, kidney, and heart.

Inhibition of Microbicidal Activity of Canine Macrophages DH82 Cell Line by Capsular Polysaccharides from Cryptococcus neoformans

Cryptococcus neoformans is a lethal fungus that primarily affects the respiratory system and the central nervous system. One of the main virulence factors is the capsule, constituted by the polysaccharides glucuronoxylomannan (GXM) and glucuronoxylomanogalactan (GXMGal). Polysaccharides are immunomodulators. One of the target cell populations for modulation are macrophages, which are part of the first line of defense and important for innate and adaptive immunity. It has been reported that macrophages can be modulated to act as a "Trojan horse," taking phagocytosed yeasts to strategic sites or having their machinery activation compromised. The scarcity of information on canine cryptococcosis led us to assess whether the purified capsular polysaccharides from C. neoformans would be able to modulate the microbicidal action of macrophages. In the present study, we observed that the capsular polysaccharides, GXM, GXMGal, or capsule total did not induce apoptosis in the DH82 macrophage cell line. However, it was possible to demonstrate that the phagocytic activity was decreased after treatment with polysaccharides. In addition, recovered yeasts from macrophages treated with polysaccharides after phagocytosis could be cultured, showing that their viability was not altered. The polysaccharides led to a reduction in ROS production and the mRNA expression of IL-12 and IL-6. We observed that GXMGal inhibits MHC class II expression and GXM reduces ERK phosphorylation. In contrast, GXMGal and GXM were able to increase the PPAR-γ expression. Furthermore, our data suggest that capsular polysaccharides can reduce the microbicidal activity of canine macrophages DH82.

Case report: MRI findings with CNS blastomycosis in three domestic cats

Blastomycosis is a systemic mycotic infection caused by dimorphic fungi. The disease is rare in cats, and reports on imaging findings with central nervous system (CNS) involvement are limited. Magnetic resonance imaging (MRI) was performed antemortem in three feline patients. Imaging findings that may allow prioritization of intracranial blastomycosis over other differential diagnoses included focal or multifocal intra-axial mass lesions with dural contact, lesion hypointensity on T2-weighted images and diffusion-weighted imaging/apparent diffusion coefficient map (DWI/ADC), strong and homogeneous contrast enhancement of the lesion(s), concurrent meningeal enhancement, marked perilesional edema and mass-effect, and ocular abnormalities. One cat was managed successfully and had a recurrence of CNS blastomycosis more than 4.5 years after the initial diagnosis. Repeat MRI at that point revealed both new and persistent (chronic) abnormalities.

MRI of CNS lymphoma with choroid plexus involvement in five dogs and one cat

OBJECTIVES

To describe the clinical features, magnetic resonance imaging (MRI) findings, and outcome of dogs and cats with central nervous system (CNS) lymphoma that involved the choroid plexus.

MATERIALS AND METHODS

A bi-institutional retrospective study of MRI of dogs and cats with CNS lymphoma, in which the choroid plexus was affected on MRI. Signalment, clinical, MRI, clinicopathologic and histopathologic findings were recorded and evaluated.

RESULTS

CNS lymphoma with choroid plexus involvement on the MRI was identified in five dogs and one cat. MRI revealed diffuse enlargement and multifocal nodularity in the choroid plexus in most cases, with the fourth ventricle the most common site affected. Five of the cases had signs of extraneural involvement (including the cat), while the sixth case was not staged. Four of five CSF samples analysed provided a diagnosis of lymphoma.

CLINICAL SIGNIFICANCE

We report MRI findings of CNS lymphoma involving the choroid plexus. These results show the importance of recognising novel imaging patterns and the potential utility of CSF collection in diagnosing CNS lymphoma involving the choroid plexus ante mortem.

[Canine meningoencephalitis and meningitis: retrospective analysis of a veterinary hospital population]

OBJECTIVE

Characterization of the etiology of meningoencephalitis and meningitis in dogs through an analysis of a veterinary hospital population.

MATERIAL AND METHODS

Retrospective study (2011-2016) with evaluation of clinical and diagnostic data of dogs with cerebrospinal fluid (CSF) pleocytosis (> 5/µl). Only dogs with cytological evaluation of CSF or pathological examination of CNS were included. Results of CSF cytology and examination for infectious diseases were reviewed.

RESULTS

A total of 62 dogs met the inclusion criteria. 14.5 % (n = 9) were classified as reactive CSF pleocytosis due to other structural CNS disease, such as neoplasia or infarct. Meningoencephalitis or meningitis of unknown origin was diagnosed in 56.5 % (n = 35). In 29.0 % (n = 18), investigations for infectious diseases or presence of bacteria in CSF cytology (n = 5) indicated an infectious etiology. This infectious etiology appeared reliable in 6 dogs (9.7 %) based on the examination findings, in 9 dogs (14.5 %), there was only a suspicion of infectious meningoencephalitis or meningitis and in 3 dogs (4.8 %), the findings were of uncertain significance.

CONCLUSION

The most common cause of CSF pleocytosis was meningoencephalitis or meningitis of unknown origin. Nevertheless, there was evidence of a possible infectious etiology in 29 % of the dogs. For a reliable diagnosis, it is important to assess the CSF cytology and to conduct investigations for infectious diseases.

CLINICAL RELEVANCE

Meningoencephalitis or meningitis of unknown origin requires immunosuppressive therapy. Therefore, CSF cytology and investigations for infectious diseases are important for an exclusion of infectious meningoencephalitis or meningitis.

Fungal Infections of the Central Nervous System in Small Animals: Clinical Features, Diagnosis, and Management

Small animal mycoses vary geographically. Different clinical presentations are seen in animals with infection of the central nervous system (CNS), including multifocal meningoencephalomyelitis, intracranial lesions that accompany sinonasal lesions, rapidly progressive ventriculitis, or solitary granuloma of the brain or spinal cord. Systemic, nasal, or extraneural clinical signs are common but, especially in granuloma cases, do not always occur. Surgery may have a diagnostic and therapeutic role in CNS granuloma. There have been recent advancements in serology. Fluconazole, voriconazole, and posaconazole cross the blood-brain barrier, but voriconazole is neurotoxic to cats. Liposomal and lipid-encapsulated formulations of amphotericin B are preferred.

Cerebral pyogranulomatous encephalitis caused by Cladophialophora bantiana in a 15-week-old domestic shorthair kitten

Case summary

A case of cerebral phaeohyphomycosis caused by Cladophialophora bantiana is described in a 15-week-old domestic shorthair kitten.

Relevance and novel information

Cerebral phaeohyphomycosis is a rare condition in cats caused by dematiaceous fungi. This report describes the clinical and histopathological findings in the youngest case documented in a feline, provides a brief review of aetiology, diagnosis, treatment and prognosis of cerebral phaeohyphomycosis and demonstrates the importance of molecular diagnostics in accurate mycotic species identification.

Hydrocephalus secondary to obstruction of the lateral apertures in two dogs

BACKGROUND

Traditionally, hydrocephalus is divided into communicating or non-communicating (obstructive) based on the identification of a blockage of cerebrospinal fluid (CSF) flow through the ventricular system. Hydrocephalus ex vacuo refers to ventricular enlargement as a consequence of neuroparenchymal loss. Hydrocephalus related to obstruction of the lateral apertures of the fourth ventricles has rarely been described.

CASE REPORT

The clinicopathologic findings in two dogs with hydrocephalus secondary to obstruction of the lateral apertures of the fourth ventricle are reported. Signs were associated with a caudal cervical spinal cord lesion in one dog and a caudal brain stem lesion in the other dog. Magnetic resonance imaging (MRI) disclosed dilation of the ventricular system, including the lateral recesses of the fourth ventricle. In one dog, postmortem ventriculography confirmed obstruction of the lateral apertures. Microscopic changes were identified in the choroid plexus in both dogs, yet a definitive cause of the obstructions was not identified. The MRI findings in both dogs are similar to membranous occlusion of the lateral and median apertures in human patients.

CONCLUSION

MRI detection of dilation of the entire ventricular system in the absence of an identifiable cause should prompt consideration of an obstruction of the lateral apertures. In future cases, therapeutic interventions aimed at re-establishing CSF flow or ventriculoperitoneal catheterisation should be considered.

A multiplex quantitative real-time polymerase chain reaction panel for detecting neurologic pathogens in dogs with meningoencephalitis

Meningoencephalitis (ME) is a common inflammatory disorder of the central nervous system in dogs. Clinically, ME has both infectious and non-infectious causes. In the present study, a multiplex quantitative real-time polymerase chain reaction (mqPCR) panel was optimized for the detection of eight canine neurologic pathogens (Blastomyces dermatitidis, Cryptococcus spp., Neospora caninum, Borrelia burgdorferi, Bartonella spp., Toxoplasma gondii, Ehrlichia canis, and canine distemper virus [CDV]). The mqPCR panel was subsequently applied to 53 cerebrospinal fluid (CSF) samples collected from dogs with ME. The analytic sensitivity (i.e., limit of detection, expressed as molecules per 1 µL of recombinant vector) was 3.8 for CDV, 3.7 for Ehrlichia canis, 3.7 for Bartonella spp., 3.8 for Borrelia burgdorferi, 3.7 for Blastomyces dermatitidis, 3.7 for Cryptococcus spp., 38 for Neospora caninum, and 3.7 for Toxoplasma gondii. Among the tested CSF samples, seven (15%) were positive for the following pathogens in decreasing order of frequency: Cryptococcus spp. (3/7), Blastomyces dermatitidis (2/7), and Borrelia burgdorferi (2/7). In summary, use of an mqPCR panel with high analytic sensitivity as an initial screen for infectious agents in dogs with ME could facilitate the selection of early treatment strategies and improve outcomes.

Successful Long-Term Use of Itraconazole for the Treatment ofAspergillusDiskospondylitis in a Dog

A 5-year-old spayed female German shepherd dog was admitted with a history of generalized stiffness. Neurologic examination revealed mild paraparesis with multifocal spinal pain. Spinal radiographs and magnetic resonance imaging revealed diskospondylitis at L6-7 and multiple sites throughout the thoracolumbar spine. Biopsy of the intervertebral disk at L6-7 revealed a positive culture forAspergillusspecies, and the dog was placed on itraconazole indefinitely. Clinical signs were significantly improved after two weeks of itraconazole. The dog was reevaluated 8 years later for unrelated reasons. No spinal pain was detected. Spinal radiographs revealed a fused L6-7 disk space and collapsed and sclerotic disk spaces at multiple sites. Itraconazole was tolerated by the dog with normal yearly liver enzyme values. To our knowledge, this is the first reported case of successful long-term use of itraconazole for the treatment ofAspergillusdiskospondylitis in a dog.

Successful management of an intracranial phaeohyphomycotic fungal granuloma in a dog

CASE DESCRIPTION

A 12-month-old castrated male Boxer was examined because of signs of acute, progressive intracranial disease.

CLINICAL FINDINGS

Cytologic and histologic findings were consistent with an intracranial fungal granuloma in the right cerebral hemisphere. Fungal culture yielded a Cladophialophora sp.

TREATMENT AND OUTCOME

The granuloma was surgically debulked to remove infected brain tissue and the avascular purulent core. Postoperatively, the patient was treated with fluconazole (2.3 mg/kg [1 mg/lb], PO, q 12 h) for 4 months, followed by voriconazole (3.4 mg/kg [1.5 mg/lb], PO, q 12 h) for a further 10 months. The outcome was considered excellent on the basis of resolution of neurologic signs and a lack of evidence of recurrence of the granuloma during magnetic resonance imaging and CSF analysis 8 months after surgery. Magnetic resonance imaging and CSF analysis 9 weeks after administration of antifungal medications was discontinued (16 months after surgery) confirmed resolution.

CLINICAL RELEVANCE

Intracranial phaeohyphomycosis in small animals is rare and is most commonly associated with Cladophialophora infection. Phaeohyphomycosis frequently causes a focal granuloma, whereas other fungal infections typically cause diffuse meningoencephalitis. In all previous reports of phaeohyphomycosis of the CNS in dogs, treatment has been limited to medical management with conventional antifungal drugs and had failed to prevent death. The present report suggested that combined management of granulomas with surgery and newer triazole medications such as voriconazole may represent a novel strategy that improves the prognosis for this disease.

Clinical and Imaging Findings in Five Dogs with Intracranial Blastomycosis (Blastomyces dermatiditis)

Fungal infections affecting the central nervous system are rare. The purpose of this study was to describe clinical and imaging findings in dogs with intracranial blastomycosis (Blastomyces dermatiditis). The radiology database was searched retrospectively for patients with a diagnosis of intracranial blastomycosis which had computed tomography performed as part of their diagnostic work-up. Medical records and imaging studies were reviewed. Five dogs met the inclusion criteria. Major presenting complaints were stertor/nasal discharge (n=2), exophthalmos (n=1), and seizures (n=2). Clinical and laboratory findings were variable. Computed tomographic examination revealed a single contrast-enhancing intra-axial mass (n=1), a nasal mass disrupting the cribriform plate (n=3), and an intracranial mass extending into the orbit and nasal cavity (n=1). Findings in intracranial blastomycosis in dogs are variable, and the disease may mimic other inflammatory disorders or neoplasia.

Granulomatous Meningoencephalitis Associated With Sporobolomyces roseus in a Dog

A German Shepherd Dog was evaluated for clinical signs of multifocal, progressive brain disease. Despite supportive care, the dog died shortly after hospital admission. Granulomatous meningoencephalitis with intralesional fungal hyphae was diagnosed postmortem. The fungus was identified as Sporobolomyces roseus by polymerase chain reaction amplification and sequencing of the ITS2 region.

Nasal cryptococcosis in two dogs in New Zealand

CASE HISTORY

Two young, large-breed female dogs were presented with an acute onset of sneezing and nasal discharge. One patient had concurrent epistaxis and facial deformity.

CLINICAL FINDINGS

Decreased airflow was noted through the left nostril in Case 1, while Case 2 showed facial deformity. Nasal radiographs from Case 1 showed a soft tissue opacity in the left nasal cavity and frontal sinus. Rhinoscopy revealed roughened, erythematous nasal turbinates in both patients, and a mass in the left caudal nasal cavity of Case 1. Cryptococcus spp. were demonstrated histopathologically on a nasal biopsy. Tissue culture and serum antigen titres were positive for Cryptococcus spp.

DIAGNOSIS

Chronic rhinitis secondary to Cryptococcus gattii infection in Case 1, and Cryptococcus neoformans infection in Case 2.

CLINICAL RELEVANCE

These are the first reported cases of Cryptococcus spp. rhinitis in dogs in New Zealand.

Cerebral Blastomyces dermatitidis infection in a cat

CASE DESCRIPTION

An 8-year-old domestic shorthair cat was evaluated because of signs of depression, circling, and visual deficits.

CLINICAL FINDINGS

The cat had no cutaneous lesions, and results of an ophthalmologic examination and thoracic radiography were within reference limits. Computed tomography of the brain revealed a mass lesion involving the right parietal, temporal, and occipital lobes; the mass was in broad-based contact with the skull and smoothly marginated and had strong homogenous enhancement after contrast agent administration. During craniectomy, samples of the mass were collected for cytologic and histopathologic evaluations and microbial culture. A diagnosis of Blastomyces dermatitidis-associated meningoencephalitis with secondary pyogranulomatous inflammation was made.

TREATMENT AND OUTCOME

Amphotericin B (0.25 mg/kg [0.11 mg/lb], IV) was administered on alternate days (cumulative dose, 1.75 mg/kg [0.8 mg/lb]). To minimize the risk of nephrotoxicosis, assessments of serum biochemical variables (urea nitrogen and creatinine concentrations) and urinalyses were performed at intervals. The third dose of amphotericin B was postponed 48 hours because the cat became azotemic. The cat subsequently received fluconazole (10 mg/kg [4.5 mg/lb], PO, q 12 h) for 5.5 months. Six months after discontinuation of that treatment, the cat appeared healthy and had no signs of relapse.

CLINICAL RELEVANCE

Brain infection with B dermatitidis is typically associated with widespread disseminated disease. The cat of this report had no evidence of systemic disease. Blastomycosis of the CNS should be considered as a differential diagnosis for brain lesions in cats from areas in which B dermatitidis is endemic.

Assessment of the IgG index in dogs by indirect immunoenzimatic assays as diagnostic tool for inflammatory diseases of central nervous system

The IgG index measures the intrathecal immunoglobulin production and it is a useful tool for diagnosis of inflammatory diseases involving the central nervous system. This index is based on the precise quantification of albumin and IgG in canine cerebrospinal fluid and serum. Here, we report the development of an indirect competitive ELISAs for the detection of both antigens. Thirty-two dogs were included in this study, divided into three experimental groups. Group A was composed of 22 healthy animals, as determined by standard clinical examination. In group B, six animals, presented neurological pathologies associated with endogenous IgG production and, in group C four animals presented neurological diseases or symptoms not associated with intrathecal IgG production. Cerebrospinal fluid and serum samples were obtained from these animals. As expected, by using the indirect ELISAs proposed here, the IgG indexes obtained in healthy animals (A) were 0.371+/-0.252 (SD). In B and C, the values (3.002+/-1.897; 0.36+/-0.306, respectively), were in agreement with the pathologic conditions of the individuals in each group. Thus, the immunometric competition ELISA methods proposed here allow the discrimination of abnormal intrathecal IgG production, in a variety of inflammatory pathologic conditions of the central nervous system.

Treatment of thoracolumbar spinal cord compression associated withHistoplasma capsulatuminfection in a cat

CASE DESCRIPTION

A 7-year-old domestic shorthair cat with a 2-month history of decreased appetite and weight loss was examined because of paraparesis of 1 week's duration that had progressed to paraplegia 3 days earlier.

CLINICAL FINDINGS

Neurologic examination revealed normo- to hyperreflexia and absence of deep pain sensation in the hind limbs and thoracolumbar spinal hyperesthesia. Neuro-anatomically, the lesion was located within the T3 through L3 spinal cord segments. Biochemical analysis and cytologic examination of CSF revealed no abnormalities. Radiography revealed narrowing of the T11-12 intervertebral disk space and intervertebral foramen suggestive of intervertebral disk disease. Myelography revealed an extradural mass centered at the T12-13 intervertebral disk space with extension over the dorsal surfaces of T11-13 and L1 vertebral bodies.

TREATMENT AND OUTCOME

A right-sided hemilaminectomy was performed over the T11-12, T12-13, and T13-L1 intervertebral disk spaces, and a space-occupying mass was revealed. Aerobic bacterial culture of samples of the mass yielded growth of a yeast organism after a 10-day incubation period; histologically, Histoplasma capsulatum was identified. Treatment with itraconazole was initiated. Nineteen days after surgery, superficial pain sensation and voluntary motor function were evident in both hind limbs. After approximately 3.5 months, the cat was ambulatory with sling assistance and had regained some ability to urinate voluntarily.

CLINICAL RELEVANCE

In cats with myelopathies that have no overt evidence of fungal dissemination, differential diagnoses should include CNS histoplasmosis. Although prognosis associated with fungal infections of the CNS is generally guarded, treatment is warranted and may have a positive outcome.

Results of magnetic resonance imaging in 14 cats with meningoencephalitis

Medical records and magnetic resonance (MR) images of 14 cats with inflammatory diseases affecting the central nervous system (CNS) were reviewed retrospectively. Cases included eight cats with feline infectious peritonitis and two cats with toxoplasmosis. Abnormalities affecting the CNS were observed in MR images in 10 (71%) cats. Intracranial lesions appeared as slightly hypointense foci in T1-weighted images in two (14%) cats, as hyperintense foci in T2-weighted images in seven (50%) cats and as hyperintense foci after intravenous administration of a gadolinium-based contrast medium in 10 (71%) cats. In six cats with lesions in T1- and/or T2-weighted images, additional lesions were visible in T1-weighted images obtained after gadolinium-based contrast medium administration. In three cats, lesions were visible only after contrast medium administration. In our study, MR imaging (MRI) did not appear to detect all cases of CNS inflammation in the population of cats with inflammatory cerebrospinal fluid (CSF); however, MRI adds information about the sites and morphology of intracranial lesions that should help to distinguish between neoplasia and inflammatory conditions and, possibly, between different inflammatory conditions.