Comparison of culture-dependent and -independent bacterial detection results on nasal swabs in dogs with nasal discharge

OBJECTIVES

The role of bacterial communities in the pathophysiology of canine nasal disease is still unclear. How and when to treat dogs with suspected secondary bacterial rhinitis and on which test to rely before making a decision to treat with antimicrobials has not been established. The objective is to compare the results of bacterial identification using agar-plate cultures and 16S rRNA gene amplicon sequencing in dogs with nasal discharge suspected to be of bacterial origin.

MATERIALS AND METHODS

Twenty-nine client-owned dogs presented for investigation of nasal disease were included in the study. Paired swabs were collected from the same affected nasal cavity. One swab was streaked on 4 agar media (Columbia Blood Agar, MacConkey, Chapman and Edward's). The other swab was stored in a sterile cryotube at -80°. Extracted DNA underwent a polymerase chain reaction targeting the V1-V3 region of the 16S rRNA gene.

RESULTS

At least one of the species detected by amplicon sequencing with a relative abundance of >10% was also identified by culture in 14 cases (48.3%), in association with marked predominance of one taxon (>80% relative abundance) in six of 14 cases. In 12 dogs (41.4%), the cultured isolates were rare or undetected components of the corresponding sequence libraries. A negative culture in the face of bacterial predominance (>50% relative abundance) of a potentially pathogenic bacteria detected by sequencing occurred in 17% (n=5) of cases; however, the use of other agar media may have decreased this percentage.

CLINICAL SIGNIFICANCE

Standard culture does not reliably predict the bacterial profile detected by 16S rRNA gene amplicon sequencing.

Laryngeal paralysis secondary to cervical bite injuries in five dogs

CASE HISTORIES

Medical records of a veterinary hospital in Belgium were reviewed for dogs (n = 5) that presented between 2016 and 2019 with laryngeal paralysis secondary to bite wounds to the cervical region received while fighting with other dogs. The time elapsed between the trauma and presentation was from a few hours up to 5 days.

CLINICAL FINDINGS AND TREATMENT

Bilateral laryngeal paralysis was identified in three dogs and unilateral laryngeal paralysis in two dogs via endoscopic assessment of laryngeal function. The primary concomitant lesions included tracheal injury in 3/5 dogs and oesophageal injury in 1/5 dogs. One dog with bilateral laryngeal paralysis was treated medically as no signs of dyspnoea were present. Surgical management was elected in 4/5 dogs based on evaluation of their clinical status and lesions revealed by endoscopic examination of upper gastrointestinal and respiratory tracts. Dogs underwent surgical procedures that were determined to be appropriate for treatment of the lesions identified on clinical examination, diagnostic imaging, and endoscopy. The cervical region was explored through a ventral midline approach in 2/4 cases, to close tracheal perforations. Temporary tracheostomy was performed in 2/4 cases. Procedures to correct brachycephalic airway obstructive syndrome were performed in 2/4 cases. Cricoarytenoid lateralisation was performed in 2/4 dogs. Dogs were hospitalised for 2-10 days and received antimicrobial therapy before surgery and for 2-3 weeks after surgery. Physical examination and respiratory function were normal in 3/5 dogs 4-6 months after discharge. Information regarding outcomes for two cases was obtained from the owners by telephone assessment 1-6 months after surgery. The owner of each dog reported the respiratory function to be excellent.

DIAGNOSIS

Uni- or bilateral, transient or permanent laryngeal paralysis with concomitant oesophageal, tracheal, or laryngeal lesions following cervical dog bite injuries diagnosed by endoscopic examination of upper gastrointestinal and respiratory tracts.

CLINICAL RELEVANCE

This case series describes the diagnosis and management of dogs with laryngeal paralysis secondary to cervical dog bite injuries. To the authors' knowledge, this is the first published report documenting bilateral laryngeal paralysis secondary to cervical dog bite injuries. Clinicians should be aware of this pathology and the importance of investigating laryngeal function in dogs presenting with cervical bites, particularly those with inspiratory dyspnoea. Upper airway and digestive endoscopy are recommended for complete assessment of cervical traumatic injuries.

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

OBJECTIVES

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.

MATERIALS AND METHODS

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.

RESULTS

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.

CLINICAL SIGNIFICANCE

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.

Angiostrongylosis in dogs with negative fecal and in-clinic rapid serological tests: 7 Cases (2013-2017)

BACKGROUND

Angiostrongylosis is considered as emerging disease in dogs in Belgium. Detection of first-stage larvae in feces using the Baermann method has an imperfect sensitivity.

OBJECTIVES

Investigation of efficacy of noninvasive blood and fecal diagnostic tests in comparison with PCR on bronchoalveolar lavage (BAL) material in a small series of coughing or dyspnoeic dogs naturally infected with Angiostrongylus vasorum.

ANIMALS

Seven dogs with angiostrongylosis.

METHODS

Retrospective study. Dogs with cough, exercise intolerance and dyspnea of 2- to 8-week duration. Diagnostic methods used included Baermann analysis, AngioDetect rapid assay, ELISAs for detection of circulating antigen and specific antibodies and qPCR on BAL material.

RESULTS

Baermann analysis, AngioDetect rapid assay, antigen ELISA, antibody ELISA, and qPCR on BAL material were positive in 3/7, 2/7, 3/6, 6/6, and 7/7 dogs, respectively. ELISA for antibodies or qPCR on BAL material were essential for definitive diagnosis in 3 dogs. Relative sensitivities of AngioDetect rapid assay, Baermann analysis, and ELISA for antigen detection were lower than 50% compared with ELISA for antibodies or qPCR on BAL material.

CONCLUSION AND CLINICAL IMPORTANCE

In this small clinical series, Baermann analysis and AngioDetect rapid assay failed to confirm the diagnosis in some dogs. Therefore, ELISA for antibody detection and qPCR on BAL material should strongly be considered in clinically suspected dogs when antigen detection methods (AngioDetect or ELISA) and Baermann analysis are negative.

Quantitative PCR and Cytology of Bronchoalveolar Lavage Fluid in Dogs with Bordetella bronchiseptica Infection

Background

The use of quantitative PCR (qPCR) for detection of Bordetella bronchiseptica in bronchoalveolar lavage fluid (BALF) and demonstration of bacteria adhering to ciliated epithelial cells in BALF or bronchial brushing fluid (BBF) has not been assessed in a series of affected dogs. Coinfections can worsen the clinical severity in bordetellosis, but the specific association with Mycoplasma cynos has not been evaluated.

Objectives

To assess the utility of culture, qPCR and cytologic examination of cytospin preparations in the diagnosis of bordetellosis in dogs and the influence of coinfection by M. cynos on disease severity.

Animals

Twenty‐four referred dogs with B. bronchiseptica infection and 10 healthy dogs.

Methods

Retrospective case series. qPCR (B. bronchiseptica and M. cynos) and culture results from BALF were recorded. Cytospin preparations from BALF and BBF were reviewed. qPCR on BALF from 10 healthy dogs were used as negative control.

Results

The BALF culture and qPCR detected B. bronchiseptica in 14/24 and 18/18 dogs, respectively. Coccobacilli were found adhering to ciliated epithelial cells in 20 of the 21 BALF cytologic preparations where epithelial cells were found, and 2/3 BBF cytologic preparations. Quantitative PCR detected a low level of B. bronchiseptica in one healthy dog. The frequency of detection of M. cynos was not significantly different in B. bronchiseptica (9/17 dogs) compared with healthy dogs (2/10 dogs) (P = .09).

Conclusion and Clinical Importance

Quantitative PCR detection of B. bronchiseptica in BALF appears to be a useful diagnostic tool. Cytologic examination of BALF or BBF, when positive, allows a rapid and reliable diagnosis.

Prevalence, location and concurrent diseases of ultrasonographic cyst-like lesions of abdominal lymph nodes in dogs

Lymph nodal cyst-like lesions are occasionally identified during abdominal ultrasound in dogs. However, a study evaluating their prevalence and clinical significance is lacking. The aim of this observational cross-sectional study was to evaluate prevalence, most common location and concurrent diseases of cyst-like lymph nodes detected during abdominal ultrasound. Affected lymph nodes, patient signalment and concurrent diseases of dogs with cyst-like lymph nodal lesions having undergone abdominal ultrasound over a one-year period were recorded. Twenty-three affected lymph nodes were observed in 17/553 dogs (prevalence=3 per cent). The most commonly affected was the lumbar lymphocenter (7/23), followed by the coeliac (6/23), the cranial mesenteric (5/23) and the iliosacral (5/23). Twenty-three concurrent diseases were diagnosed in 17 dogs, among which 16/23 were non-neoplastic (70 per cent). The most common concurrent disease was renal insufficiency (8/23), followed by neoplasia (7/23), gastroenteropathy (3/23), benign prostatic disease (2/23), pancreatitis (1/23), peritonitis (1/23) and neurological disease (1/23). No statistical correlation existed between cyst-like lymph nodal lesion and a specific neoplastic or non-neoplastic disease. In conclusion, in the present study, cyst-like lymph nodal lesions have a low prevalence, involve different lymphocenters and were found in dogs affected by different diseases, including both non-neoplastic and neoplastic aetiologies.

Detection of Angiostrongylus vasorum by quantitative PCR in bronchoalveolar lavage fluid in Belgian dogs

OBJECTIVES

To describe Angiostrongylus vasorum infection in a series of clinical cases over a 12-month period, report the use of quantitative PCR on broncho-alveolar lavage fluid and investigate the -possibility of previously undiagnosed angiostrongylosis in a retrospective cohort of coughing and healthy dogs.

METHODS

Pulmonary angiostrongylosis was diagnosed based on compatible clinical signs and positive quantitative PCR on broncho-alveolar lavage fluid and/or positive Baermann examination. Quantitative PCR was also performed retrospectively on broncho-alveolar lavage fluid from 65 dogs (55 coughing and 10 healthy dogs), examined between 2008 and 2014; results of Baermann examination were also available in 33 dogs.

RESULTS

Seven young adult dogs from Southeastern Belgium with respiratory clinical signs were diagnosed with angiostrongylosis between March 2013 and April 2014. Positive broncho-alveolar lavage fluid quantitative PCR results and positive Baermann examination were obtained in 5/5 and 2/5 dogs, respectively. In the remaining two dogs, only Baermann analysis was performed. Among the retrospective cohorts, only one broncho-alveolar lavage fluid from a coughing dog was quantitative PCR-positive whereas all faecal samples were negative.

CLINICAL SIGNIFICANCE

Until recently, canine angiostrongylosis was not reported in Belgium. It should now be included in the differential diagnosis of coughing Belgian dogs. Identification of affected dogs may be aided by quantitative PCR on broncho-alveolar lavage fluid.

Detection of Aspergillus-specific antibodies by agar gel double immunodiffusion and IgG ELISA in feline upper respiratory tract aspergillosis

Feline upper respiratory tract aspergillosis (URTA) is an emerging infectious disease. The aims of this study were: (1) to assess the diagnostic value of detection of Aspergillus-specific antibodies using an agar gel double immunodiffusion (AGID) assay and an indirect immunoglobulin G (IgG) ELISA; and (2) to determine if an aspergillin derived from mycelia of Aspergillus fumigatus, Aspergillus niger and Aspergillus flavus can be used to detect serum antibodies against cryptic Aspergillus spp. in Aspergillus section Fumigati. Sera from cats with URTA (group 1: n = 21) and two control groups (group 2: cats with other upper respiratory tract diseases, n = 25; group 3: healthy cats and cats with non-respiratory, non-fungal illness, n = 84) were tested. Isolates from cats with URTA comprised A. fumigatus (n = 5), A. flavus (n = 1) and four cryptic species: Aspergillus felis (n = 12), Aspergillus thermomutatus (Neosartorya pseudofischeri, n = 1), Aspergillus lentulus (n = 1) and Aspergillus udagawae (n = 1). Brachycephalic purebred cats were significantly more likely to develop URTA than other breeds (P = 0.013). The sensitivity (Se) of the AGID was 43% and the specificity (Sp) was 100%. At a cut-off value of 6 ELISA units/mL, the Se of the IgG ELISA was 95.2% and the Sp was 92% and 92.9% for groups 2 and 3 cats, respectively. Aspergillus-specific antibodies against all four cryptic species were detected in one or both assays. Assay Se was not associated with species identity. Detection of Aspergillus-specific antibodies by IgG ELISA has high Se and Sp for diagnosis of feline URTA.

Clinical findings and prevalence of the mutation associated with primary ciliary dyskinesia in Old English Sheepdogs

Background

Primary ciliary dyskinesia (PCD) is generally a recessively inherited disorder characterized by dysfunction of motile cilia. A mutation in a new causative gene (CCDC39) has been identified in the Old English Sheepdog (OES).

Objectives

To describe the clinical findings and the molecular changes of affected dogs and estimate the worldwide prevalence of the mutation in a large cohort of OES.

Animals

578 OES, including 28 affected and 550 clinically healthy dogs.

Methods

This retrospective study reviewed the data of OES diagnosed with PCD and OES tested for the mutation. Clinical data including results of physical examination and further investigations were obtained on 11/28 dogs. CCDC39 expression was assessed by qRT‐PCR and Western blot analysis in affected dogs and healthy dogs. DNA was extracted on 561/578 dogs and a genetic test by Taqman technology was developed to genotype the CCDC39 mutation in these dogs.

Results

Clinical findings were recurrent nasal discharge and cough, pyrexia, leucocytosis, and bronchopneumonia. Ultrastructural defects were characterized by central microtubular abnormalities and decreased number of inner dynein arms (IDAs). Molecular analysis revealed a reduced expression of CCDC39 RNA and an absence of CCDC39 protein in affected dogs compared to healthy dogs. The mutation was more frequent in nonrandomly selected European OES population with a higher proportion of carriers (19%) compared to non‐European dogs (7%).

Conclusion and Clinical Importance

CCDC39 mutation is dispersed in a worldwide population and is responsible for PCD in this breed. Genetic testing might enable control of this disease.

Cytokine and transcription factor expression by Aspergillus fumigatus-stimulated peripheral blood mononuclear cells in dogs with sino-nasal aspergillosis

The causal agent of sino-nasal aspergillosis is usually Aspergillus fumigatus, which is a saprophytic and ubiquitous fungus that causes a severe rhinosinusitis in apparent healthy dogs. Affected dogs do not have systemic immuno-suppression. It has been shown previously that dogs affected by this disease have local over-expression of interleukin (IL)-10 and Th1 cytokines in nasal mucosal tissue. The aim of the present study was to assess the response of peripheral blood mononuclear cells (PBMC) from affected and unaffected dogs to antigen-specific stimulation with heat-inactivated Aspergillus spp. conidia, by quantifying gene expression for specific Th1, Th2, Th17 and Treg cytokines and their related transcription factors. Quantification of IL-4 and IFN-γ protein in culture supernatant was performed by enzyme-linked immunosorbent assay (ELISA). PBMC from dogs with SNA produced adequate mRNA encoding IFN-γ and IFN-γ protein. The expression of IL-17A mRNA was significantly greater in PBMC of affected compared with unaffected dogs. The amount of IL-10 mRNA in PBMC from affected dogs decreased after antigen-specific challenge. These results suggest that the incapacity of affected dogs to clear these fungal infections is not related to a defect in Th1 immunity or to an overwhelming regulatory reaction, but rather to an uncontrolled pro-inflammatory reaction driven by Th17 cells.

Potential role of Alternaria and Cladosporium species in canine lymphoplasmacytic rhinitis

OBJECTIVES

To evaluate the possible role of Alternaria and Cladosporium species in the pathogenesis of canine lymphoplasmacytic rhinitis by comparing the amount of specific fungal DNA in nasal mucosal biopsies between dogs without nasal neoplasia and those with lymphoplasmacytic rhinitis or nasal neoplasia.

METHODS

Quantitative real-time polymerase chain reaction (qPCR) assays detecting DNA from Alternaria and Cladosporium fungi were applied to nasal mucosal biopsies collected from dogs with lymphoplasmacytic rhinitis (n = 8), dogs with nasal neoplasia (n = 10) and control animals (n = 10). A copy number for each sample was calculated using a standard curve of known copy number and differences amongst groups were assessed using Kruskal-Wallis tests.

RESULTS

No significant difference was found between the groups. Low levels of Alternaria DNA (10-100 copies/PCR) were detected in one sample; very low levels of DNA (<10 copies/qPCR) were detected in 6 samples, and 21 samples were negative. Low levels of Cladosporium DNA were detected in 2 samples; very low levels of DNA in 18; and 8 were negative.

CLINICAL SIGNIFICANCE

Results of this study reveal that Alternaria and Cladosporium species are part of the canine nasal flora, and that these fungi are probably not involved in the pathogenesis of lymphoplasmacytic rhinitis.

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

OBJECTIVES

To evaluate the most appropriate sampling procedure and the effect of incubation temperature on fungal culture in the diagnosis of canine sinonasal aspergillosis (SNA).

METHODS

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.

RESULTS

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.

CLINICAL SIGNIFICANCE

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 (CAPurAspAg) 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 CAPurAspAg 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 CAPurAspAg, 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 Plateliat test is unreliable for the diagnosis of canine SNA.

Distribution of leucocyte subsets in the canine pharyngeal tonsil

This report describes the distribution and nature of lymphoid tissue in the nasopharyngeal mucosa of six puppies (mean age+/-SD, 0.3+/-0.25 years) and eight adult dogs (mean age+/-SD, 8.8+/-2.67 years) without respiratory disease. A non-encapsulated area of organized mucosa-associated lymphoid tissue was observed in the caudal part of the posterior wall of the nasopharynx, distal to the openings of the auditory tubes. This structure was consistent with the pharyngeal tonsil and was microscopically more extensive in puppies than in adult dogs. Histochemistry and immunohistochemistry were used to characterize and enumerate the leucocyte subsets in this part of the nasopharynx. Mast cells were found immediately beneath the respiratory epithelium but were also scattered in the glandular and muscular tissue. IgA(+) plasma cells outnumbered IgG(+) and IgM(+) plasma cells, especially in the glandular tissue. All classes of plasma cells were present in significantly greater numbers in adults than in puppies. MHC class II(+) cells were mainly observed in areas containing diffuse and follicular aggregates of lymphoid cells. Both MHC class II(+) cells and CD1c(+) cells with a dendritic morphology were predominantly found immediately beneath or within the epithelium, and cells expressing these markers were more abundant in puppies than in adult dogs. The anti-L1 marker labelled low numbers of cells with a neutrophilic morphology, which were significantly more abundant in puppies than in adult dogs. The majority of lymphoid cells were CD3(+) T lymphocytes and these were particularly abundant in areas containing aggregates of lymphoid cells; CD4(+), CD8(+) and TCR alphabeta(+) cells had the same distribution as the CD3(+) cells. CD4(+) cells were more numerous than CD8(+) cells. The quantitative and qualitative data obtained will enable comparisons to be made with similar studies in dogs suffering from nasopharyngeal diseases, or when the local immune system needs to be investigated.

Diagnosis of pharyngeal disorders in dogs: a retrospective study of 67 cases

OBJECTIVES

To assess the frequency distribution of pharyngeal disorders and to compare clinical signs in diseases of the different pharyngeal areas. To review the investigation methods.

METHODS

Medical records of 67 dogs presenting with abnormalities of the pharyngeal area were retrospectively reviewed and classified according to the anatomic area involved, i.e. the nasopharyngeal, oropharyngeal and laryngopharyngeal areas. Clinical signs, endoscopic findings and results of additional sampling were reviewed.

RESULTS

Nasopharyngeal disorders were most frequently encountered (49 per cent), with choanal masses being the most frequent diagnosis (24 of 33), followed by laryngopharyngeal disorders (37.5 per cent) and oropharyngeal disorders (10.5 per cent). A rare condition, stenosis of the intrapharyngeal opening, was classified separately (3 per cent). An overall good correlation between matched cytology and histopathology samples was found. In all categories of diseases, clinical signs related to both the upper respiratory and digestive tracts were reported.

CLINICAL SIGNIFICANCE

Pharyngeal disorders are more frequently localised in the nasopharyngeal area and include essentially choanal masses. The use of a flexible endoscope for retrograde rhinoscopy is essential for adequate investigation of the proximal nasopharyngeal area. Clinical signs do not allow differentiation of the pharyngeal disorder within the different pharyngeal areas.