Canine Sino-nasal Aspergillosis Research Articles

Comparison of two minimally invasive enilconazole perendoscopic infusion protocols for the treatment of canine sinonasal aspergillosis.

To compare two minimally invasive enilconazole infusion protocols for the treatment of canine sinonasal aspergillosis and evaluate the importance of complete endoscopic debridement in determining first treatment success rate. Data for 48 dogs with confirmed sinonasal aspergillosis treated with endoscopic debridement followed by per-endoscopic enilconazole infusion were collected. Twenty-four dogs were treated according to the previously published 1-hour infusion protocol and 24 dogs underwent a simplified 15-minute infusion protocol. Completeness of debridement, evaluated as partial or complete at the end of the procedure and outcome after one or several treatments were assessed in all dogs. Multi-variable analysis was performed to derive odds ratios and 95% confidence intervals. The median duration of the simplified protocol - 92∙3 minutes (range 40 to 140) - was substantially shorter than the duration of the previous protocol - 201∙3 minutes (range 120 to 265). First treatment success rates were 58 and 62∙5% for the previous and simplified protocol, respectively. Overall treatment success rate was similar in both groups (96%). Complete debridement was associated with an improved first treatment success rate compared to partial debridement. The simplified protocol is a valid alternative approach to the treatment of sinonasal aspergillosis. Completeness of endoscopic debridement before infusion is an important step for the success of treatment in canine sinonasal aspergillosis.

Treatment of canine sinonasal aspergillosis with clotrimazole infusion in patients with cribriform plate lysis.

To describe the treatment of sinonasal aspergillosis with topical 1% clotrimazole solution in dogs with cribriform plate lysis. This retrospective study includes data retrieval from medical records of dogs with sinonasal aspergillosis and cribriform plate lysis that underwent topical treatment with 1% clotrimazole solution. Five dogs with sinonasal aspergillosis, cribriform plate lysis diagnosed on CT scans, and normal neurologic examinations were treated with a single (n=3) or multiple (n=2) infusions of clotrimazole solution. No dogs developed clinical neurologic disease after therapy. In this study, a topical clotrimazole solution was not associated with adverse neurologic effects in neurologically normal dogs with sinonasal aspergillosis and cribriform plate lysis.

Spatial Patterns and Impacts of Environmental and Climatic Factors on Canine Sinonasal Aspergillosis in Northern California.

Sinonasal aspergillosis (SNA) causes chronic nasal discharge in dogs and has a worldwide distribution, although most reports of SNA in North America originate from the western USA. SNA is mainly caused by Aspergillus fumigatus, a ubiquitous saprophytic filamentous fungus. Infection is thought to follow inhalation of spores. SNA is a disease of the nasal cavity and/or sinuses with variable degrees of local invasion and destruction. While some host factors appear to predispose to SNA (such as belonging to a dolichocephalic breed), environmental risk factors have been scarcely studied. Because A. fumigatus is also the main cause of invasive aspergillosis in humans, unraveling the distribution and the environmental and climatic risk factors for this agent in dogs would be of great benefit for public health studies, advancing understanding of both distribution and risk factors in humans. In this study, we reviewed electronic medical records of 250 dogs diagnosed with SNA between 1990 and 2014 at the University of California Davis Veterinary Medical Teaching Hospital (VMTH). A 145-mile radius catchment area around the VMTH was selected. Data were aggregated by zip code and incorporated into a multivariate logistic regression model. The logistic regression model was compared to an autologistic regression model to evaluate the effect of spatial autocorrelation. Traffic density, active composting sites, and environmental and climatic factors related with wind and temperature were significantly associated with increase in disease occurrence in dogs. Results provide valuable information about the risk factors and spatial distribution of SNA in dogs in Northern California. Our ultimate goal is to utilize the results to investigate risk-based interventions, promote awareness, and serve as a model for further studies of aspergillosis in humans.

Assessment of Toll-like receptor 2, 4 and 9 SNP genotypes in canine sino-nasal aspergillosis.

BackgroundThe exact aetiology of canine sino-nasal aspergillosis (SNA) is unknown. In man, dysfunction in innate immunity, particularly in the function of pattern recognition receptors, is implicated in the pathogenesis of inflammatory sino-nasal disease and in fungal diseases. Associations between single nucleotide polymorphisms (SNPs) in Toll-like receptors (TLRs) and these diseases have been identified. Similarly, in dogs SNPs in genes encoding TLRs may be important in the pathogenesis of SNA. The aims of the present study were (1) to identify the presence of non-synonymous SNPs in the coding regions of the TLR2, 4 and 9 genes in dogs suffering from SNA, and (2) to investigate the SNP genotypes in dogs with SNA compared with a control population.ResultsDirect sequencing of nine dogs of various breeds with SNA revealed two non-synonymous SNPs in the coding region of TLR2, eight in TLR4 and four in TLR9. These non-synonymous SNPs were further evaluated in a case-control study of affected Golden Retrievers, Labrador Retrievers, Rottweilers and Beaucerons. Genotyping was performed using a combination of allele-specific primers and hydrolysis probe assays in 31 dogs with SNA and 31controls. No significant difference in minor allele frequency was identified between these groups, for all studied SNPs, in any of the four breeds.ConclusionsThese findings do not support a role for non-synonymous SNPs in the TLR 2, 4 and 9 coding regions in the pathogenesis of canine SNA, but do not exclude a role for innate immunity in the pathogenesis of the disease.

Computed tomographic features of feline sino-nasal and sino-orbital aspergillosis

Feline upper respiratory tract aspergillosis (URTA) occurs as two distinct anatomical forms, namely, sino-nasal aspergillosis (SNA) and sino-orbital aspergillosis (SOA). An emerging pathogen, Aspergillus felis, is frequently involved. The pathogenesis of URTA, in particular the relationship between the infecting isolate and outcome, is poorly understood. In this study, computed tomography was used to investigate the route of fungal infection and extension in 16 cases (SNA n = 7, SOA n = 9) where the infecting isolate had been identified by molecular testing.All cases had nasal cavity involvement except for one cat with SNA that had unilateral frontal sinus changes. There was a strong association between the infecting species and anatomic form (P = 0.005). A. fumigatus infections remained within the sino-nasal cavity, while cryptic species infections were associated with orbital and paranasal soft-tissue involvement and with orbital lysis. Cryptic species were further associated with a mass in the nasal cavity, paranasal sinuses or nasopharynx. Orbital masses showed heterogeneous contrast enhancement, with central coalescing hypoattenuating foci and peripheral rim enhancement. Severe, cavitated turbinate lysis, typical of canine SNA, was present only in cats with SNA. These findings support the hypothesis that the nasal cavity is the portal of entry for fungal spores in feline URTA and that the route of extension to involve the orbit is via direct naso-orbital communication from bone lysis. Additionally, a pathogenic role for A. wyomingensis and a sinolith in a cat with A. udagawae infection are reported for the first time.

What causes canine sino-nasal aspergillosis? A molecular approach to species identification

On the basis of phenotypic identification methods, Aspergillus fumigatus is reported as the most commonly identified aetiological agent of canine sino-nasal aspergillosis (SNA). However, definitive identification of Aspergillus spp. using phenotypic features alone is unreliable. The aim of this study was to determine the molecular identities of fungal species causing SNA in dogs. Genomic DNA was extracted from 91 fungal isolates from 90 dogs diagnosed with SNA in Australia, the USA and Belgium, and the ITS1-5.8S-ITS2 ribosomal DNA and partial β-tubulin regions were sequenced. Eighty-eight of 91 (96.7%) isolates were identified as A. fumigatus and 3/91 (3.3%) belonged to Aspergillus section Nigri spp. (Aspergillus tubingensis: 2/91; Aspergillus uvarum: 1/91). These findings confirm that A. fumigatus is the most common aetiological agent of canine SNA. This is the first report to document a pathogenic role for A. tubingensis and A. uvarum in dogs.

TLR-2 but not TLR-9 is up-regulated in the Central Nervous System and Lymphoid Organs during Canine Visceral Leishmaniasis.

TLR-2 but not TLR-9 is up-regulated in the Central Nervous System and Lymphoid Organs during Canine Visceral Leishmaniasis.

Toll- and NOD-like receptor mRNA expression in canine sino-nasal aspergillosis and idiopathic lymphoplasmacytic rhinitis

The pathogenesis of canine sino-nasal aspergillosis (SNA) and lymphoplasmacytic rhinitis (LPR) remains poorly understood. The innate immune system is implicated in the etiology of human chronic rhinosinusitis. Therefore, we hypothesized that dysfunction in innate immunity could be implicated in the pathogenesis of SNA and LPR.Expression of messenger RNA (mRNA) encoding Toll-like receptors (TLRs) 1–10 and NOD-like receptors (NODs) 1 and 2 in nasal mucosal biopsies from SNA or LPR dogs was compared with mucosa from healthy controls. Gene expression was quantified using quantitative real-time reverse transcriptase polymerase chain reaction normalized against multiple housekeeper genes.All TLR and NOD genes were quantified in all samples. SNA was associated with significantly increased expression of TLRs 1–4, 6–10; and NOD2, relative to controls. LPR was associated with significantly increased expression of TLRs 1, 2, 6–8, relative to controls. There was significantly more expression of TLRs 1, 4, 6–10 and NOD2 in SNA dogs than in LPR dogs. The significance of these differences in the pathogenesis of these diseases is yet to be determined.

Effect of sampling method and incubation temperature on fungal culture in canine sinonasal aspergillosis

To evaluate the most appropriate sampling procedure and the effect of incubation temperature on fungal culture in the diagnosis of canine sinonasal aspergillosis (SNA). Sixteen dogs with SNA and 20 dogs with non-fungal nasal disease entered a prospective study. Nasal secretions and mucosal biopsies were collected in all dogs. Fungal plaques were also sampled in dogs with SNA. Each specimen was taken in duplicate from each dog and incubated at room temperature and 37 degrees C. In dogs with SNA, nasal secretions, mucosal biopsies and fungal plaques yielded fungal growth at room temperature in one, one and seven dogs, respectively, whereas fungal growth was obtained at 37 degrees C in three, 12 and 14 dogs, respectively. No specimen collected from any dog with non-fungal nasal disease yielded fungal growth at room temperature or at 37 degrees C. The diagnosis of canine SNA is more likely to be confirmed following culture of mucosal biopsies or fungal plaques than nasal secretions sampled blindly with swabs. Incubating cultures at 37 degrees C is more likely to provide a diagnostic outcome than when samples are cultured at room temperature. Fungal culture of nasal specimens has good specificity for the diagnosis of SNA in dogs.

Comparison of the value of measurement of serum galactomannan and Aspergillus-specific antibodies in the diagnosis of canine sino-nasal aspergillosis

Serology is currently used for the diagnosis of canine sino-nasal aspergillosis (SNA). However, the accuracy of serological testing using commercially available, standardized purified antigen preparations of Aspergillus (CAPur AspAg) has only been poorly documented. The aim of the present study was to assess the diagnostic value of an agar-gel double immunodiffusion (AGDD) test and an anti- Aspergillus IgG ELISA, using CAPur AspAg and the commercially available Platelia™ test for the detection of serum galactomannan. Sera from 17 dogs with SNA, 18 dogs with a nasal tumour (NT), 11 dogs with lymphoplasmacytic rhinitis (LPR) and 33 control dogs were tested with the 3 methods. AGDD result was positive in 76.5% of dogs with SNA, whereas all sera from dogs with non-fungal nasal disease and control dogs were negative. A positive IgG ELISA result was obtained in 88% of dogs with SNA and in 18% of dogs with LPR. All patients with NT and control dogs had a negative IgG ELISA result. The Platelia™ test was positive in 24% of dogs with SNA, 11% of dogs with NT, 9% of dogs with LPR and 24% of control dogs. The results of this study suggest that (1) the detection of serum Aspergillus-specific antibodies with AGDD or ELISA, using CAPur AspAg, provides excellent specificity and good sensitivity, (2) the specificity is higher for AGDD (100%) than for ELISA (96.8%) while sensitivity is higher for ELISA (88.2%) than for AGDD (76.5%) and (3) serum galactomannan quantification with the Platelia™ test is unreliable for the diagnosis of canine SNA.

Canine sino-nasal aspergillosis: parallels with human disease

Canine sino-nasal aspergillosis (SNA) is characterized by the formation of a superficial mucosal fungal plaque within the nasal cavity and/or frontal sinus of systemically healthy dogs. The most common causative agent is Aspergillus fumigatus. The fungus does not invade beneath the level of mucosal epithelium but incites a severe chronic inflammatory response that leads to local destruction of nasal bone. These clinicopathological features are equivalent to those of human chronic erosive non-invasive fungal sinusitis. The clinical diagnosis of canine SNA relies on multiple modalities but local instillation of anti-fungal agents is an effective therapy with high cure-rate. Recent studies have investigated the immunopathogenesis of canine SNA. The mucosal inflammatory infiltrate involves a mixture of CD4+ and CD8+ T lymphocytes, IgG+ plasma cells and activated macrophages and dendritic cells expressing class II molecules of the major histocompatibility complex. There is active recruitment of blood monocytes and neutrophils. Real-time quantitative reverse transcriptase polymerase chain reaction (qRT-PCR) analysis of mucosal tissue samples has revealed up-regulation of Th1 (IL-12, IL-18 and IFN-gamma), Th17-related (IL-23) and pro-inflammatory (IL-6, TNF-alpha) cytokine mRNA with evidence of expression of genes encoding monocyte chemoattractant proteins 1-4. Additionally, there is significant transcription of the IL-10 gene consistent with local immunosuppression that prevents secondary immune-mediated sequelae whilst permitting chronicity of the infection. The source of this IL-10 may be a T regulatory population or a Th1 population that switches phenotype during the course of disease. This understanding of the immunopathogenesis of canine SNA establishes this disorder as a valuable model for the equivalent human pathology.

Whole blood and tissue fungal DNA quantification in the diagnosis of canine sino-nasal aspergillosis

Various combinations of tests are used to confirm the diagnosis of canine sino-nasal aspergillosis (SNA) because false-positive and false-negative results can occur with each test. Therefore, the aim of this study was to evaluate whether detection of fungal DNA in blood and nasal tissue samples was of value in the clinical diagnosis of this disease. Four groups were included in the study (dogs with SNA, lymphoplasmacytic rhinitis or nasal neoplasia, and control animals). Real-time PCR assays detecting DNA from all Penicillium and Aspergillus species (PenAsp assay) or species-specific DNA from A. fumigatus, A. terreus, A. flavus and A. niger were applied to whole blood and nasal tissue samples. Results obtained by PCR were compared between the groups. Sensitivity, specificity, positive and negative predictive values (PPV and NPV) for fungal DNA detection were compared with those for alternative diagnostic procedures including histopathology, serology and fungal culture. Significantly more fungal DNA was detected by the PenAsp assay in tissue biopsies from dogs with SNA than in the three other groups. Sensitivity, specificity, PPV and NPV for this method were 1.00, 0.06, 0.32 and 1.00. A. fumigatus DNA was detected in seven tissue biopsies from dogs with SNA and in one biopsy from a dog with a nasal tumour. Sensitivity, specificity, PPV and NPV for this diagnostic test were 0.50, 0.97, 0.87 and 0.82. No significant difference was found between the groups with respect to the amount of DNA detected in blood by the PenAsp assay. Sensitivity, specificity, PPV and NPV for this method were 0.71, 0.24, 0.31 and 0.64. A. fumigatus DNA was detected in the blood of three dogs with SNA and sixteen dogs without SNA. Sensitivity, specificity, PPV and NPV for this diagnostic tool were 0.21, 0.45, 0.15 and 0.54. Detection of A. fumigatus DNA in nasal tissue had the highest specificity, PPV and NPV but sensitivity of this method was low. Detection of fungal DNA in whole blood was of no value in the diagnosis of SNA.

Distinct tissue cytokine and chemokine mRNA expression in canine sino-nasal aspergillosis and idiopathic lymphoplasmacytic rhinitis

Idiopathic lymphoplasmacytic rhinitis (LPR) and sino-nasal aspergillosis (SNA) are among the most common causes of nasal discharge in dogs. The pathogenesis of both diseases is poorly understood. Some have proposed that LPR is a chronic inflammatory response to an inhaled irritant, pollutant or allergen, but others suggest that most cases of LPR constitute undiagnosed cases of SNA. Local immune dysfunction is thought to permit opportunist infection in canine SNA. This study investigates the nature of the local tissue immune response mounted in canine LPR and SNA in order to determine whether these diseases have similar or distinct pathogenesis . Quantitative reverse transcriptase polymerase chain reaction was carried out on RNA isolated from nasal biopsies from diseased and control dogs, using specific assays designed to amplify messenger RNA (mRNA), encoding a panel of cytokines and chemokines. SNA was associated with significantly increased expression of mRNA encoding interleukin (IL)-6, IL-8, IL-10, IL-12p19, IL-12p35, IL-12p40, IL-18, IFN-γ, TNF-α, TGF-β, eotaxin-2 and all four monocyte chemoattractant proteins (MCPs) relative to controls. LPR was associated with significantly increased expression of mRNA encoding IL-5, IL-8, IL-10, IL-12p19, IL-12p40, IL-18, TNF-α, TGF-β, MCP-2 and MCP-3 relative to controls. There was significantly more expression of mRNA encoding IL-6, IL-8, IL-10, IL-12p35, IL-12p40, IL-18, IFN-γ, TNF-α, TGF-β and all MCPs, and significantly less expression of IL-5 in dogs with SNA than in dogs with LPR. Thus, the profile of cytokine and chemokine gene expression in the nasal mucosa is different in dogs with LPR when compared to dogs with SNA. A partial Th2 immune response appears to be mounted in the nasal mucosa of dogs with LPR, whereas the mucosal immune response in canine SNA is of the Th1 type. Increase in IL-10 and TGF-β transcripts in dogs with SNA is thought to be implicated in the failure to clear the Aspergillus infection. These results constitute the first evidence that the pathogenesis of canine LPR and SNA is distinct.

Canine Nasal Aspergillosis

Chronic nasal discharge is a common clinical sign of disease in dogs. Canine sinonasal aspergillosis is a relatively common disease in dogs. The three hallmarks of canine nasal aspergillosis are a profuse mucoid to hemorrhagic chronic nasal discharge that may alternate with periods of epistaxis, ulceration of the external nares with crusting, and pain or discomfort in the facial region. Diagnostic imaging (preferably computed tomography, CT) of the nasal cavity and paranasal sinuses is an important component of the evaluation of dogs with signs of nasal disease. Rhinoscopy is an important part of both the diagnosis and the therapy for nasal aspergillosis. Therapeutic recommendations for sinonasal aspergillosis have included surgery and the use of several systemic and topical antifungal drugs.

Quantification of mRNA encoding cytokines and chemokines in nasal biopsies from dogs with sino-nasal aspergillosis

Canine sino-nasal aspergillosis is usually caused by Aspergillus fumigatus and is similar to human chronic erosive non-invasive fungal sinusitis. The pathogenesis of the disease is poorly understood. We investigated the nature of the local immune response mounted in canine sino-nasal aspergillosis. Quantitative RT-PCR was carried out on RNA isolated from nasal biopsies from diseased and control dogs, using specific assays designed to amplify mRNA encoding a panel of cytokines and chemokines. Canine sino-nasal aspergillosis was associated with significantly increased expression of mRNA encoding MCP-1, -2, -3 and -4, IL-8, IL-10, IL-18 and TNF-α relative to controls ( P < 0.01) but there was no difference between groups with respect to IL-4, IL-5, IL-6, IL-12, TGF-β, and eotaxin-2 and -3. The up-regulation of proinflammatory cytokines and chemokines related to the influx of phagocytic cells might account for the localisation of this infection to the upper respiratory tract. The up-regulation of the expression of the immunomodulatory cytokine IL-10 in nasal tissue from affected dogs might be important in limiting the extent of local tissue destruction, but might also account for the fact that infected dogs are generally unable to clear this infection spontaneously.