M. Sharman

Sinonasal aspergillosis in dogs: a review

Sinonasal aspergillosis is an uncommon, yet debilitating and often frustrating condition to treat in dogs despite years of research evaluating pathogenesis, diagnosis and treatment. The disease is most commonly caused by non-invasive fungal infection, thought to be secondary to altered innate and/or adaptive immune responses. Attempts to confirm this have however failed. A variety of conflicting opinions regarding the diagnosis and treatment of sinonasal aspergillosis exist. Often the use of a particular treatment protocol is based upon personal or regional preference. Evaluation of the veterinary literature demonstrates that the evidence base in support of individual treatment recommendations is weak. A number of recent publications have helped to expand the current knowledge base and therefore our understanding of important practicalities for both diagnostic options and treatment protocols. The following review examines the current evidence for the pathogenesis of sinonasal aspergillosis in dogs, as well as the various diagnostic options. The available evidence for frequently utilised -therapeutic options and their likely outcomes is also explored.

Multi-centre assessment of mycotic rhinosinusitis in dogs: a retrospective study of initial treatment success (1998 to 2008)

OBJECTIVES To retrospectively review the first treatment response of dogs with mycotic rhinosinusitis to commonly utilised treatment techniques. METHODS Medical records of dogs treated for mycotic rhinosinusitis were obtained retrospectively via a manual review of the clinical databases of six veterinary referral centres for the period of January 1998 to June 2008, and first treatment outcome was evaluated. Historical and clinicopathological findings were also reviewed to evaluate their impact on treatment success or failure. RESULTS There was no significant difference in first treatment outcome between treatment groups (P=0.21). When all topical treatments were considered together (n=85), 39 dogs (45.8%) had a successful first treatment. Initial treatment success was associated with a younger age (56.3 versus 75.8 months; P=0.02) and was 2.7 times more likely in dogs with unilateral disease, although this was not significant (P=0.07). Adjunctive therapy with systemic antifungal agents was associated with treatment failure (P< or =0.01). Fifty-nine dogs (69.4%) responded successfully following multiple treatments. CLINICAL SIGNIFICANCE Treatment of mycotic rhinosinusitis remains challenging, and multiple treatments are frequently required for adequate treatment. Reasons for first treatment failure are likely multifactorial in origin, making it difficult to predict those dogs that are likely to have a superior prognosis, regardless of the treatment type used.

Activated coagulation times in normal cats and dogs using MAX-ACT tubes.

OBJECTIVE To establish reference values for activated coagulation time (ACT) in normal cats and dogs, by visual assessment of clot formation using the MAX-ACT(TM) tube. SUBJECTS We recruited 43 cats and 50 dogs for the study; 11 cats and 4 dogs were excluded from the statistical analysis because of abnormalities on clinical examination or laboratory testing including anaemia, prolonged prothrombin time (PT) or activated partial thromboplastin time (APTT), or insufficient plasma volume for comprehensive laboratory coagulation testing. PROCEDURE Blood samples were collected via direct venipuncture for MAX-ACT, packed cell volume/total solids, manual platelet estimation and PT/APTT measurement. Blood (0.5 mL) was mixed gently in the MAX-ACT tube at 37 degrees C for 30 s, then assessed for clot formation every 5 to 10 s by tipping the tube gently on its side and monitoring for magnet movement. The endpoint was defined as the magnet lodging in the clot. The technique was tested with 10 dogs by collecting two blood samples from the same needle insertion and running a MAX-ACT on each simultaneously. RESULTS In normal cats the mean MAX-ACT was 66 s (range 55-85 s). In normal dogs the mean was 71 s (range 55-80 s). There was no statistical difference between the first and second samples collected from the same needle insertion. CONCLUSIONS and Clinical Relevance In both cats and dogs, a MAX-ACT result >85 s should be considered abnormal and further coagulation testing should be performed. Additionally, failure to discard the first few drops of the sample does not appear to significantly affect results.

Clotrimazole and enilconazole distribution within the frontal sinuses and nasal cavity of nine dogs with sinonasal aspergillosis

OBJECTIVES Multiple topical treatments are often required for clinical cure of mycotic rhinosinusitis in dogs. The objective of this study was to describe the distribution and retention of enilconazole and clotrimazole solutions using a temporary trephination protocol. METHODS Nine client-owned dogs diagnosed with mycotic rhinosinusitis between March 2008 and December 2009 were prospectively enrolled and were sequentially allocated to receive treatment with either clotrimazole (1% in polyethylene glycol) or enilconazole (10% solution), after imaging and rhinoscopic assessment. Both frontal sinuses were trephined, debrided and flushed with saline. Infusion was administered via frontal sinuses with dogs in sternal recumbency and computed tomography (CT) performed 5 minutes after completion. Distribution was scored 1 to 4 at the canine tooth, premolar 4, cribriform plate and frontal sinus on both sides, for a maximum score of 32. RESULTS Distribution of antifungal agents to all regions of the nasal cavity and frontal sinuses was achievable, but varied considerably. Retention was poor in 10 of 18 regions assessed. CLINICAL SIGNIFICANCE Distribution of antifungal agents within the frontal sinuses is achievable using temporary trephination; however, distribution is variable and retention is often poor.

The exogenous fluorophore, fluorescein, enables in vivo assessment of the gastrointestinal mucosa via confocal endomicroscopy: optimization of intravenous dosing in the dog model.

This study described the pharmacokinetics of the intravenous fluorophore, fluorescein, and aimed to evaluate its utility for use in upper gastrointestinal confocal endomicroscopy (CEM). Six healthy, mature, mixed-breed dogs were anesthetized and then dosed intravenously with fluorescein at 15 mg/kg. Blood samples were collected at predetermined time-points. Dogs were examined by upper gastrointestinal confocal endomicroscopy and monitored for adverse effects. Plasma fluorescein concentrations were measured using high-performance liquid chromatography (HPLC) with UV/Vis detection. Mean plasma concentration at 5 min was 57.6 ± 18.2 mg/L, and plasma concentrations decreased bi-exponentially thereafter with a mean concentration of 2.5 mg/L ± 1.26 at 120 min. Mean terminal plasma elimination half-life (t½β ) was 34.8 ± 8.94 min, and clearance was 9.1 ± 3.0 mL/kg/min. Apparent volume of distribution at steady-state was 0.3 ± 0.06 L/kg. Fluorescein provided optimal fluorescent contrast to enable in vivo histologically equivalent evaluation of topologic mucosal morphology within the first 30 min following intravenous administration. Adverse effects were not observed. Based upon the calculated clearance, a constant rate infusion at a rate of 0.18 mg/kg/min is predicted to be adequate, following an initial loading dose (2 mg/kg), to maintain plasma concentration at 20 mg/L for optimal CEM imaging during the study period.

In Vivo Histologically Equivalent Evaluation of Gastric Mucosal Topologic Morphology in Dogs By using Confocal Endomicroscopy

Background Confocal endomicroscopy (CEM) is an endoscopic technology permitting in vivo cellular and subcellular imaging. CEM aids real‐time clinical assessment and diagnosis of various gastrointestinal diseases in people. CEM allows in vivo characterization of small intestinal mucosal morphology in dogs. Objective To determine the feasibility of CEM to evaluate gastric mucosal morphology in dogs and to characterize the appearance in healthy dogs. Animals Fourteen clinically healthy research colony dogs. Methods Experimental study. Under general anesthesia, dogs underwent standard endoscopic evaluation and CEM of the gastric mucosa. In the initial 6 dogs, fluorescent contrast was provided with the fluorophore acriflavine (0.05% solution), applied topically. Subsequently, 8 dogs were assessed using a combination of fluorescein (10% solution, 15 mg/kg IV), followed by acriflavine administered topically. For each fluorophore, a minimum of 5 sites were assessed. Results Confocal endomicroscopy provided high quality in vivo histologically equivalent images of the gastric mucosa, but reduced flexibility of the endoscope tip limited imaging of the cranial stomach in some dogs. Intravenous administration of fluorescein allowed assessment of cellular cytoplasmic and microvasculature features. Topical application of acriflavine preferentially stained cellular nucleic acids, allowing additional evaluation of nuclear morphology. Identification of Helicobacter‐like organisms was possible in 13 dogs. Conclusion and Clinical Importance Confocal endomicroscopy provides in vivo images allowing assessment of gastric mucosal morphology during endoscopy, potentially permitting real‐time diagnosis of gastrointestinal disease.

Clinical resolution of a nasal granuloma caused by Trichosporon loubieri

The current report describes the diagnosis of a nasopharyngeal granuloma due to a fungal infection by Trichosporon loubieri. This is the first report of successful treatment of nasal granuloma formation caused by Trichosporon species infection in a cat.

Concurrent somatotroph and plurihormonal pituitary adenomas in a cat

An 8-year-old, male neutered, domestic longhair cat was referred for investigation of insulin-resistant diabetes mellitus. Routine haematology, serum biochemistry, urinalysis (including culture), total T4 and urine creatinine:cortisol ratio were unremarkable, but markedly increased insulin-like growth factor-1 concentration was identified and a pituitary mass was subsequently documented. The cat was treated conservatively with the dopamine agonist L-deprenyl and was re-presented 16 months later for worsening polyuria, polydipsia, polyphagia, marked lumbar muscle atrophy, development of a pendulous abdomen and marked thinning of the abdominal skin. Hyperadrenocorticism was diagnosed based on abdominal ultrasonography, dexamethasone suppression testing and endogenous adrenocorticotropic hormone (ACTH). The cat was treated with trilostane (30 mg q24h PO) and showed some clinical improvement, but developed an opportunistic fungal infection and skin fragility syndrome 4.5 months after commencing treatment, and was euthanased. A double-pituitary adenoma comprising a discrete somatotroph adenoma and a separate plurihormonal adenoma (positive immunoreactivity for ACTH, melanocyte-stimulating hormone and follicle-stimulating hormone) was identified on post-mortem examination. These two pituitary adenomas were suspected to have arisen as independent neoplastic entities with the plurihormonal tumour either being clinically silent at the initial presentation or having developed over the subsequent 16 months.

Gastrokine mRNA expression in gastric tissue from dogs with helicobacter colonisation but without inflammatory change during treatment

Gastrokines (GKNs) are bioactive substances secreted by gastric cells. Evidence supports functional roles for GKNs in gastric homeostasis, immune responses and tumour suppression. Down-regulation has been reported in Helicobacter pylori associated gastritis and other inflammatory gastrointestinal conditions in mice and people. The aim of this study was to evaluate GKN gene expression in dogs positive for other Helicobacter spp. both before and after treatment. Expression of Gkn-1 and Gkn-2 mRNA was studied in endoscopic biopsy samples collected from seven healthy dogs over three time-points pre- (T0) and at 1 and 18 weeks post-treatment for Helicobacter spp. colonisation (T1 & T2). The relative expression software tool (REST) was used to provide efficiency corrected expression ratios for comparisons between groups and these results were compared to a standard 2ΔΔCT methodology. Compared with T1 Gkn1 and Gkn2 mRNA expression was greater at T0 by a mean factor of 2.53 (SE=1.83-3.54) for Gkn1 (P=0.000) and 2.85 (SE=2.23-3.75) for Gkn2 (P=0.000). This difference was attenuated when comparisons were made between T0 and T2. Histopathological evidence of gastritis was not present in any Helicobacter spp. positive sample. When compared to post-eradication samples Gkn gene expression is increased in the presence of Helicobacter spp. in dogs without evidence for concurrent inflammation. Further evaluation is required to determine the relevance of this finding, however given a suspected role in gastric homeostasis, up-regulation of GKN1 and GKN2 could limit development of gastritis in Helicobacter spp. positive dogs.

Comparison of in vivo confocal endomicroscopy with other diagnostic modalities to detect intracellular helicobacters.

Intracellular colonisation may serve as a protected niche where Helicobacter spp. organisms evade effective treatment. In dogs, non-Helicobacter pylori-helicobacters are frequently intracellular. Confocal endomicroscopy allows in vivo gastrointestinal imaging and has aided real-time identification of Helicobacter pylori and other intracellular and mucosally associated bacteria. The objectives of this study were: (1) to determine the utility of confocal endomicroscopy to identify non-Helicobacter pylori-helicobacters compared with other diagnostic modalities, and (2) to assess its ability to identify intracellular organisms. Fourteen clinically healthy dogs underwent standard gastroduodenoscopy followed by confocal endomicroscopy using topical acriflavine. Confocal images were obtained from at least five gastric sites. Endoscopic biopsies were obtained for histopathology, PCR and fluorescence in situ hybridisation (FISH). Methodologies were compared for their ability to determine the presence and spatial distribution of gastric helicobacters in dogs. Confocal endomicroscopy provided high quality images allowing in vivo identification of non-Helicobacter pylori-helicobacters in 13 dogs. Histopathology identified helicobacters in 11 dogs. Organisms were identified within the superficial gastric mucus and within gastric pits, and distribution throughout the stomach was diffuse and multi-focal. Confocal endomicroscopy findings correlated with PCR and FISH post-procedure analysis. Only FISH identified intracellular organisms, which were present in 13/14 dogs. Confocal endomicroscopy provided in vivo histology images and was capable of identifying non-Helicobacter pylori-helicobacters during gastroscopy, but was unable to identify intracellular organisms using the current fluorophore protocol.