ABSTRACT Background Bronchoalveolar lavage fluid (BALF) analysis is a key diagnostic tool in veterinary respiratory medicine. The IDEXX ProCyte Dx analyzer was developed for blood formulation and cellular counting in various fluids, but its applicability for BALF analysis remains unexplored. Objectives To assess the agreement between manual counting and automated counting using the IDEXX ProCyte Dx analyzer for total cell count (TCC) and differential cell count (DCC) in BALF samples from healthy and diseased dogs, under two pretreatment conditions: mucolytic treatment with dithiothreitol (DTT) or filtration. Methods BALF from 10 healthy beagles and 14 diseased dogs were analyzed to compare TCC and DCC between manual and automated methods across pretreatment conditions. Results In healthy dogs, Bland–Altman analysis on log‐transformed data demonstrated a mean ratio close to 1 and acceptable 95% limits of agreement between manual and automated methods and between pretreatment conditions. In diseased dogs, good agreement was observed between manual and automated methods for filtered samples only; the other comparisons showed poor agreement. In both healthy and diseased dogs, Passing‐Bablok regression analysis did not detect systematic or proportional bias between methods. Automated DCC was inconsistent compared with manual methods in both healthy and diseased dogs. Conclusions The IDEXX ProCyte Dx analyzer can be used for TCC measurement of pre‐treated BALF samples in healthy dogs. In diseased dogs, filtration is preferred over DTT‐treatment for automated counting, and results should be interpreted with caution due to the unpredictable influence of pretreatment on cellular counts. For DCC, automated methods are unreliable.

BACKGROUND:Upper respiratory tract diseases in companion animals encompass various diagnoses and anatomical localizations that are challenging to distinguish based solely on clinical signs. HYPOTHESIS/OBJECTIVES:Assess associations between signalment and clinical signs, and the localization and categories of nasal and nasopharyngeal diseases in dogs and cats. ANIMALS:A total of 396 client-owned animals (167 cats, 229 dogs) presented for nasal or nasopharyngeal disease at the Veterinary Teaching Hospital of the University of Liège (Belgium) between 2018 and 2022. METHODS:Retrospective observational cross-sectional study. Univariate and multivariate logistic regressions were used to identify associations between signalment and clinical signs and disease type or localization. RESULTS:Nasopharyngeal disease in cats was associated with stertor (odds ratio [OR], 10.1; 95%CI, 2.2-47.3; P = .003), dyspnea (OR, 6.5; 95%CI, 2.0-21.6; P = .002), absence of sneezing (OR, 0.1; 95%CI, 0.03-0.4; P < 0.001), and nasal discharge (OR, 0.04; 95%CI, 0.007-0.2; P < .001). In dogs, nasal and nasopharyngeal localizations were, respectively, associated with sneezing (OR, 95.6; 95%CI, 9.3-987.9; P < .001) and reverse sneezing (OR, 5.7; 95%CI, 1.3-25.2; P = .02). Although epistaxis was associated with both fungal rhinitis and nasal masses in dogs, only masses were associated with decreased nasal airflow (OR, 29.4; 95%CI, 8.1-106.9; P < .001), whereas it was preserved in fungal rhinitis (OR, 0.02; 95%CI, 0.003-0.15; P < .001). Systemic signs were observed in cats with nasal masses (OR, 7.3; 95%CI, 2.5-21.3; P < .001); in dogs, they were linked to fungal rhinosinusitis (OR, 26.1; 95%CI, 3.9-176.0; P < .001). CONCLUSIONS AND CLINICAL IMPORTANCE:Signalment and clinical signs provide valuable indicators for diagnosis and localization of nasal diseases in dogs and cats, which may guide clinical decision-making.

Chronic bronchial diseases (CBD) associated with bronchiectasis (BE) and/or bronchomalacia (BM) are commonly diagnosed in dogs. Their pathogenesis remains incompletely understood, and recent studies have questioned the clinical relevance of distinguishing BE and/or BM, suggesting that their pathogenic mechanisms may overlap and that differentiating between them may have limited clinical significance. To date, the role of neutrophil extracellular traps (NETs) in BE and/or BM remains undetermined. This study aimed to validate NETs detection techniques in banked canine bronchoalveolar lavage fluid (BALF) using healthy (H) dogs, as negative controls, dogs with bacterial bronchopneumonia (BBP), as positive controls, and to compare NET detectability in dogs with CBD associated with BE and/or BM. A retrospective observational study was conducted using client-owned dogs presented with CBD and BE, BM, or BEBM based on endoscopic findings, or BBP. NETs were measured in BALF by quantification of cell-free DNA (cfDNA), detection of myeloperoxidase (MPO)-DNA complexes via enzyme-linked immunosorbent assay (ELISA) and by confocal laser scanning microscopy of immunofluorescent labeled samples. cfDNA concentrations were significantly higher in BBP dogs than in CBD or H-dogs, with no significant differences among the CBD groups. MPO-DNA complex levels were significantly higher in dogs with CBD and BBP than in H-dogs, with BE dogs showing the greatest increase compared with H and BM dogs, and BEBM dogs also exceeding H-dogs. Across all dogs, MPO-DNA complexes correlated positively with total and absolute neutrophil counts, neutrophil percentage, cfDNA concentrations, and duration of clinical signs. These associations varied between groups, with the strongest and most consistent correlations observed in BE-dogs. This study indicates that NETs are detected and quantifiable in the BALF of dogs with CBD and BE and/or BM and dogs with BBP. Their presence suggests that NET formation may play a role in the pathogenesis of CBD, especially in cases involving BE. Further research is needed to explore the role of NETs as well as the therapeutic potential of NET modulation in respiratory diseases.

IntroductionSinonasal aspergillosis (SNA) is a frequent cause of chronic nasal discharge, predominantly caused by Aspergillus fumigatus. The infection is typically confined to the nasal cavity and/or frontal sinuses, characterized by superficial mucosal fungal plaques and associated with severe lymphoplasmacytic and neutrophilic inflammation of the mucosa. While Neutrophil Extracellular Traps (NETs) have been demonstrated to restrict fungal hyphal proliferation in animal models, their presence and role in canine SNA remain unexplored.MethodsIn this study, we quantified the presence of NETs in nasal lavage fluid (NALf) or nasal mucosal biopsies from dogs diagnosed with SNA and healthy controls. To unambiguously detect NETs, we employed three detection techniques. The first method consisted in cell-free DNA detection in NAL. The second method measured myeloperoxidase (MPO)-DNA complexes in NAL by ELISA. The third method aimed to directly identify NETs in nasal biopsies by confocal microscopy and characterize histopathological lesions associated to NETs-enriched areas in corresponding adjacent hematoxylin-eosin tissue sections.ResultsInterestingly, we were only able to detect NETs in biological samples of dogs with SNA but not in samples from control dogs. Furthermore, NETs-enriched areas were specifically restricted to the surface of the epithelial barrier, where they surrounded fungal spots.ConclusionThese results suggest that NETs are involved in the inflammatory response occurring in SNA and likely regulate disease progression. Whether they limit the fungal propagation or contribute to the pathogenesis of the disease remains to be determined, before assessing their role as potential therapeutic target.

BACKGROUND:Eosinophilic bronchopneumopathy (EBP) in dogs is an idiopathic disease presumably caused by hypersensitivity to causative allergens that remain unidentified. In humans, allergic bronchopulmonary aspergillosis (ABPA) is a hypersensitivity to Aspergillus fumigatus in uncontrolled asthma in patients. HYPOTHESIS/OBJECTIVES:Investigate potential implications of A fumigatus and other ubiquitous antigens (house dust mites, HDMs) in dogs with EBP compared to healthy dogs and dogs with chronic bronchitis (CB). ANIMALS:Paired serum and bronchoalveolar lavage fluid (BALF) from dogs with EBP or CB and healthy dogs. METHODS:Case-control observational study. Quantitative PCR (qPCR) for A fumigatus was performed on BALF and A fumigatus-specific antibodies were investigated using a validated ELISA on serum and BALF. An ELISA also was performed for HDM-specific antibodies. RESULTS:Aspergillus fumigatus qPCR was weakly positive in BALF in 2 of 23 EBP dogs and negative in all other dogs. Concentrations of A fumigatus-specific immunoglobulin E (IgE) in serum and BALF were very low and did not differ between groups. Concentrations of A fumigatus-specific serum immunoglobulin G (IgG) were higher in EBP dogs than in CB dogs and healthy dogs (P = .01) but concentrations in BALF were not different. Concentrations of HDM-specific IgG were higher in both serum and BALF in EBP dogs compared with CB dogs (P = .01). CONCLUSIONS AND CLINICAL IMPORTANCE:Higher concentrations of serum IgG for A fumigatus and HDM observed in EBP dogs might suggest an IgG-dependent disease. Based on our results, EBP is not mediated by A fumigatus-specific IgE.

Canine idiopathic pulmonary fibrosis (CIPF) is a progressive parenchymal lung disease of unknown origin, primarily affecting older West Highland white terriers (WHWTs). The aims of this study were to describe demographic characteristics of a large cohort of WHWTs with CIPF and to investigate potential predictive factors associated with disease occurrence and mortality, using a questionnaire-based survey.Completed surveys were obtained from 457 respondents representing 542 WHWTs, of which 29.7% were reported to suffer from CIPF. Descriptive statistics were used to characterize the population. Univariate and multivariable logistic regression analyses were performed to identify predictive factors associated with CIPF diagnosis and mortality.Median age at diagnosis was 11.6 years (interquartile range: 9.1-13.3). Lung crackles were reported in 87% of affected dogs. At the time of survey completion, 54.9% of CIPF-affected WHWTs were deceased. Median survival time following diagnosis was 1 year (interquartile range: 0.32-2 years), and cause of death was CIPF-related in 77% of cases.After adjustment for confounding factors, increased odds of CIPF were associated with older age, United Kingdom residence, familial history of CIPF, cardiac disease, regular grooming in dedicated facilities, and treatment for external parasites. Conversely, having a pedigree was associated with reduced odds of disease. Among affected dogs, living in homes containing asbestos increased odds of death, whereas cardiac disease and frequent home grooming were associated with reduced odds of mortality.These findings suggest that genetic background, environmental exposures, care-related factors, and comorbid conditions may influence the occurrence and outcome of CIPF in the studied WHWT population.

Canine idiopathic pulmonary fibrosis (CIPF) is a fatal disease affecting primarily West Highland white terriers (WHWT). CIPF remains challenging to diagnose and disease progression is difficult to predict. Recently, fibroblast activation protein (FAP) was identified as a cellular marker of active fibrosis in post-mortem lung biopsies from CIPF-affected WHWTs. Therefore, FAP-targeted imaging using FAP inhibitors (FAPI) may offer a noninvasive means of assessing active fibrosis in canine lungs in vivo. This study aimed to evaluate whether [18F]FAPI-74 positron emission tomography (PET) combined with computed tomography (CT) can detect FAP expression in the lungs of CIPF-affected WHWTs. This prospective exploratory pilot study included two healthy senior purpose-bred Beagle dogs and two client-owned WHWTs diagnosed with CIPF. In addition to CT, each dog underwent a 90-min dynamic thoracic PET scan following intravenous administration of [18F]FAPI-74 (median activity 10.3 MBq/kg). In one Beagle and one WHWT, a subsequent static abdominal PET scan was performed to assess biodistribution. PET and CT images were co-registered prior to quantitative uptake analysis. [18F]FAPI-74 PET was well tolerated in all dogs and compatible with clinical use. [18F]FAPI-74 uptake was approximately three-fold higher in CIPF-affected lungs than in healthy lungs. Tracer elimination occurred via both urinary and hepatobiliary routes. Moderate uptake was also observed in gastrointestinal organs, potentially reflecting age-related fibrosis, as supported by additional immunohistochemistry. In conclusion, [18F]FAPI-74 PET/CT enables in vivo detection of active pulmonary fibrosis in CIPF-affected dogs and represents a promising noninvasive tool for detecting and monitoring this fatal disease.

Background/Objectives: Methicillin-resistant Staphylococcus aureus (MRSA) and methicillin-resistant Staphylococcus pseudintermedius (MRSP) represent important antimicrobial resistance threats related to companion animals, which can directly or indirectly lead to adverse health effects in humans and animals living in close contact. Characterizing the phenotypic resistance of MRSA and MRSP to a panel of antimicrobials relevant to both veterinary and human medicine is crucial within a “One Health” framework. Methods: In this study, a total of 79 presumptive MRSA isolates (34 from cats, 45 from dogs) and 110 presumptive MRSP isolates (105 from dogs, 5 from cats) from clinical cases were analysed. Real-time PCR was used to detect the presence of mecA and mecC genes, and susceptibility testing was performed using the Sensititre EUST2 panel. Results: Most of the isolates (88.9%, 168/189) were positive for the mecA gene, while a minority (1.1%, 2/189) were mecC-positive (2 MRSA, 1 dog, 1 cat). MRSP isolates exhibited acquired resistance to a broader range of antibiotics compared to MRSA strains. Furthermore, several isolates demonstrated acquired resistance to antibiotics considered critically important for human medicine. Resistance to vancomycin was found in an MRSP isolate from a dog, and resistance to linezolid in an MRSP isolate from a cat. This study reveals that 83.3% (30/36) of MRSA isolates from dogs and 89.3% (25/28) from cats were multidrug-resistant organisms, while MRSP isolates exhibited multidrug resistance in 99% (101/102) of cases for dogs and 100% (4/4) for cats. Conclusions: The extremely high level of multidrug resistance, with some isolates resistant to critically important antibiotics used in human medicine, highlight the importance of monitoring antimicrobial susceptibility in MRSA and MRSP isolates collected from cats and dogs in a One Health perspective.

Bronchiectasis (BE) and bronchomalacia (BM) are chronic respiratory diseases in dogs, yet their combined occurrence (BEBM) is not well studied. This retrospective study analyzed 65 dogs diagnosed via endoscopy with BE, BM, or BEBM (E-BE, E-BM, E-BEBM) to identify clinical and pathological differences and assess how imaging results (radiography and computed tomography (CT)) align with endoscopic findings. Clinical symptoms like coughing, dyspnea, and exercise intolerance were similar across all groups, except lung crackles, which were more common in E-BEBM. Inflammation seen during bronchoscopy and bronchoalveolar lavage fluid results, including neutrophil counts, showed no significant differences between groups. Bacterial infections were present in 15% of dogs with no difference among groups. Diagnostic agreement between radiography and endoscopy was low: 18.1% for E-BE, 10.5% for E-BM, and 38.4% for E-BEBM. CT results matched endoscopic findings in all E-BE cases but only in half of E-BM and 40% of E-BEBM cases. The bronchial-to-arterial ratio, a benchmark for BE diagnosis, did not align with CT findings. Overall, the study found limited clinical or pathological differences between BE, BM, and BEBM and limited concordance between imaging and endoscopic findings, emphasizing the need for further research to clarify potential implications for treatment strategies.

Chronic bronchitis (CB) in dogs involves persistent inflammation of the bronchial walls and excessive mucus production within the airways, with or without bronchial infection, and may lead to degenerative airway changes such as bronchiectasis (BE) and bronchomalacia (BM). Standardized treatment protocols for CB with concurrent BE and/or BM (BEBM) are lacking. This article proposes a therapeutic approach for dogs with CB and BEBM, based on veterinary literature and relevant human medical data. Two treatment algorithms are outlined, depending on the presence or absence of cytological evidence of bacterial infection in bronchoalveolar lavage fluid (BALF) and/or bronchial brush samples. For cases with suspected infection, indicated by intracellular bacteria on cytology, first-line therapy with oral doxycycline is recommended pending BALF culture and quantitative polymerase chain reaction (qPCR) results. If warranted, antibiotic therapy should be escalated stepwise after culture/qPCR confirmation, in accordance with antimicrobial stewardship principles. In non-infectious inflammatory cases, inhaled glucocorticoids are advised as first-line therapy and may also be used in infectious cases unresponsive to antibiotics alone. Mucoactive agents and cough suppressants are not recommended in the initial protocol but may be considered as adjunctive, symptom-targeted treatments on a case-by-case basis, avoiding unnecessary or unsupported interventions. These proposed algorithms are not intended as definitive clinical guidelines, but as a starting point for discussion and future validation. They emphasize rational and prudent use of antibiotics, alone or alongside anti-inflammatory therapy, to improve patient outcomes while minimizing antimicrobial resistance risks. Further research is needed to assess the long-term efficacy of this approach.

Canine idiopathic pulmonary fibrosis (CIPF) is an interstitial lung disease reported in West Highland white terriers (WHWTs). B-mode ultrasonography (US) is used in human medicine as an adjunct tool for interstitial lung disease, including idiopathic pulmonary fibrosis. In veterinary medicine, thoracic US has been described as helpful for the diagnosis of various pulmonary diseases. The aim of this study was to describe the thoracic B-mode US findings in CIPF WHWTs, compared with those in control WHWTs. Twenty-seven WHWTs, including CIPF and control WHWTs, were prospectively enrolled. Standardised thoracic B-mode US was performed. The presence of an irregular pleural surface, ring-down artefact and peripheral nodules was assessed and scored for each location. An overall cumulative score was calculated by adding the individual scores of each location. WHWTs affected with CIPF had significantly higher overall scores compared to the control group. The ring-down artefact score was significantly higher in the CIPF group compared to the control group. No preferential location for the lesions was observed. A cut-off value of 15 ring-down artefacts for the entire thorax predicted CIPF in WHWTs with a sensitivity of 76.5% and a specificity of 80% (AUC 0.815). The present study describes B-mode US findings in CIPF WHWTs.

Single cell RNA sequencing (scRNA-seq) can be used to resolve the cellular and molecular heterogeneity within a tissue by identifying cell populations with an unprecedented granularity along with their transcriptional signatures. Yet, the single cell gene expression profiles of cell populations in the healthy canine lung tissue remain unexplored and such analysis could reveal novel cell populations or markers lacking in dogs and facilitate comparisons with lung diseases. Using fresh healthy lung biopsies from four dogs, we conducted droplet-based scRNA-seq on 26,278 cells. We characterized 46 transcriptionally distinct cell subpopulations across all lung tissue compartments including 23 immune, 13 mesenchymal, five epithelial and five endothelial cell subpopulations. Of note, we captured rare cells such as unconventional T cells or Schwann cells. Differential gene expression profiles identified specific markers across all cell subpopulations. Fibroblasts clusters exhibited a marked transcriptional heterogeneity, some of which might exert immune regulatory functions. Finally, the integration of canine lung cells with an annotated human lung atlas highlighted many similarities in gene expression profiles between species. This study thus provides an extensive molecular cell atlas of the healthy canine lung, expanding our knowledge of lung cell diversity in dogs, and providing the molecular foundation for investigating lung cell identities and functions in canine lung diseases. Besides, the occurrence of spontaneous lung diseases in pet dogs, with phenotypes closely resembling those in humans, may provide a relevant model for advancing research into human lung diseases.

Canine sinonasal aspergillosis (SNA) is a poorly understood disease and remains a challenge to treat. Hypovitaminosis D is associated with many infectious diseases in humans and Vitamin D (VitD) deficiency in experimental mice decreases resistance to Aspergillus fumigatus. The objective of this study was to determine whether dogs with SNA have different VitD metabolite concentrations compared to healthy dogs (HD) and dogs with other nasal conditions and if those concentrations change after cure for SNA dogs. Twenty-two dogs with SNA, 12 HD, 9 dogs with lymphoplasmacytic rhinitis (LPR) and 10 dogs with nasal neoplasia (NN) were included. Serum 25-hydroxyvitamin D2 (25(OH)D2), 25-hydroxyvitamin D3 (25(OH)D3), 24,25-dihydroxyvitamin D3 (24,25(OH)2D3), 3-epimer-25-hydroxyvitamin D3 (3-epi-25(OH)D3) concentrations were measured by a certified liquid chromatography tandem mass spectrometry method at time of diagnosis or revisit. Twelve SNA dogs were available for serial blood collection until cure. Serum 25(OH)D and 24,25(OH)2D3 were lower in dogs with SNA (mean ± standard deviation; 23 ng/ml ± 7.3 and 10.2 ng/ml ± 4.2, respectively) than in HD (34.1 ng/ml ± 7.5; P = 0.007 and 18.2 ng/ml ± 5.4; P = 0.002) while there was no difference among the other groups. Cured SNA dogs had higher serum 25(OH)D concentrations (27.7 ng/ml ± 9.4) compared to before treatment (23.1 ng/ml ± 7.7; P = 0.0002). These results further support the rationale that VitD may play a role in the complex SNA pathophysiology. Whether lower VitD status contributes to the development of the disease or is a consequence of it is unknown.

Chemokine (C-C motif) ligand 2 (CCL2) is a strong monocyte chemoattractant that has been shown to be increased in humans and dogs with neoplasia. Although in human urothelial carcinoma (UCa) CCL2 levels increase with metastatic disease, a previous study showed an opposite trend in dogs. The aim of this study was to assess serum CCL2 levels in dogs with mast cell tumours (MCT) and insulinoma with or without metastasis. The second aim was to evaluate any correlation between CCL2 serum levels and circulating monocyte counts in UCa, MCT and insulinoma. Serum CCL2 levels were significantly higher in dogs affected with MCT or insulinoma compared to healthy dogs (p = 0.002 and p = 0.017, respectively). Furthermore, low levels of serum CCL2 were associated with metastasis in insulinoma-affected dogs (p = 0.04) similarly to UCa-affected dogs. However, in the MCT group, low levels of serum CCL2 were associated with non-metastatic disease (p = 0.0045). Based on receiver operating characteristic (ROC) curves, optimal cut-off values were determined for CCL2 concentration in order to calculate sensitivity and specificity of the test. Good accuracy was reached for CCL2 as a diagnostic marker, but it was poor as a staging marker. In conclusion, a dual role of CCL2 has been shown in different tumour types. A low level of CCL2 was associated with metastatic disease in dogs with insulinoma similarly to UCa-affected dogs. In contrast, a low level of CCL2 was associated with a non-metastatic disease in dogs with MCT. There was only a moderate correlation between CCL2 and circulating monocyte count in our study in both Uca and MCT, and a fair opposite correlation in insulinoma, leading to hypothesise that the influx of monocytes may be better observed in the tumour itself rather than in the circulation. These results could help to further understand CCL2 in the tumour microenvironment and its possibility as a therapeutic target.

A 5-year-old female neutered Dogue de Bordeaux was referred for evaluation of acute respiratory distress. The dog was initially presented to the attending veterinary surgeon with acute inspiratory stridor and respiratory distress of approximately 12 h duration. A temporary tracheostomy was performed prior to referral. Upon referral, endoscopic examination revealed dorsal displacement of edematous glosso-epiglottic mucosa with secondary epiglottic entrapment, with concurrent severe local oedema. Resection of the glosso-epiglottic folds and staphylectomy allowed resolution of the acute dyspnoea and rapid patient discharge without associated complications. This case report presents a unique presentation of laryngeal obstruction secondary to severe oedema and static displacement of redundant glosso-epiglottic mucosa in a dog without previous history of dyspnoea, exercise intolerance, snoring or episodes of respiratory distress.

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(degrees). 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.

OBJECTIVE:To determine and compare the concentration of gentamicin in the lower airways and serum of healthy spontaneously breathing dogs after nebulization with 5% undiluted gentamicin during 3 versus 10 minutes.ANIMALS:10 healthy experimental Beagles.METHODS:This was a prospective crossover study. A standardized bronchoalveolar lavage (BAL) procedure was performed in each dog after 1 week of administration of each of 2 different gentamicin nebulization protocols separated by a 1-week washout period. The 2 protocols consisted of nebulization of 5% undiluted gentamicin (50 mg/mL) twice daily either during 10 minutes per session (± 95 mg; 10-minute protocol) or 3 minutes per session (± 28 mg; 3-minute protocol). BAL fluid (BALF) was obtained under general anesthesia using a bronchoscope within 15 minutes after administration of the last nebulization. Blood was collected within 5 minutes after BALF collection. BALF and serum gentamicin concentrations were determined by particle-enhanced turbidimetric inhibition immunoassay. Concentrations between protocols were compared using a paired t test.RESULTS:Both BALF and serum gentamicin concentrations were higher after the 10-minute protocol compared with the 3-minute protocol (mean ± SD: 2.41 ± 0.87 mg/L vs 1.25 ± 0.31 mg/L, P = .001; and 1.02 ± 0.59 mg/L vs 0.31 ± 0.24 mg/L, P < .0001 in BALF and serum, respectively), while the BALF-to-serum ratio did not differ between the protocols (3.75 [1.37 to 5.75] (median [IQR]) in the 3-minute protocol vs 2.48 [2.02 to 2.67] in the 10-minute protocol; P = .754).CLINICAL RELEVANCE:A 3-minute nebulization of gentamicin seems to achieve sufficient concentrations of gentamicin in the BALF to have good efficacy against aminoglycoside-sensitive bacteria while remaining below the toxic range values in blood.

Canine idiopathic pulmonary fibrosis (CIPF) is a progressive fibrotic interstitial lung disease of unknown etiology, afflicting aging West Highland white terriers (WHWTs) and leading to progressive respiratory failure. Fibroblast activation protein (FAP), a protease overexpressed in many cancers, is upregulated in idiopathic pulmonary fibrosis in humans. The aim of this study was to investigate FAP as a marker of active fibrosis in lung biopsies from WHWTs affected with CIPF, as well as the potential of plasmatic FAP as a biomarker. After establishing a scoring system to evaluate the severity and activity of fibrosis on histopathological lung sections, anti-FAP immunohistochemistry was performed on healthy and CIPF samples. FAP expression was characterized using both visual and digital quantitative pathology software analyses and then correlated to fibrosis severity and activity. Levels of plasmatic FAP in WHWTs affected with CIPF were measured by enzyme-linked immunosorbent assay and compared with healthy dogs. Lung samples from 22 WHWTs affected with CIPF were collected. According to the fibrosis scoring system, they were classified as cases of mild (5), moderate (9) and severe (8) fibrosis and were attributed scores of fibrosis activity. Fifteen healthy lung samples were classified as non-fibrotic. Healthy lung samples were FAP-negative, whereas fibroblasts were FAP-positive in 20 CIPF samples. FAP immunohistochemical expression correlated mildly with fibrosis severity (p < 0.05; R2 = 0.22) but highly with fibrosis activity scores (p < 0.001; R2 = 0.68). Digital image analysis detected a higher percentage of FAP-positive cells in areas of active fibrosis (p < 0.001) and FAP-positive cells were distributed outside mature fibrosis lesions, clustered in active fibrosis areas or scattered within alveolar septa. On the other hand, plasmatic FAP was significantly lower in dogs affected with CIPF compared with healthy dogs (p < 0.01). In conclusion, this study provides a valuable histological scoring system to assess the severity and activity of fibrosis in CIPF. It demonstrates that FAP is a good cellular marker of fibrotic activity in CIPF, and thus constitutes a promising target to be exploited for diagnostic and therapeutic applications. Additionally, it suggests that plasmatic FAP, although non-specific, could be altered in CIPF.

Antimicrobials’ topical administration efficacy has not been assessed in dogs with upper respiratory tract disease. The aim was to compare the concentration of gentamicin in nasal lavage fluid (NALF) and in serum after three topical protocols. This was a prospective crossover study of ten healthy dogs. Gentamicin was nebulized for a duration of 1 week, twice a day, for 10 min in the first protocol (10-min protocol) and for 3 min in the second protocol (3-min protocol), while the third protocol consisted of the administration of 0.25 mL of gentamicin in each nostril (drop protocol). Median concentrations of gentamicin in NALF were 9.39 µg/mL (8.12–19.97 interquartile range), 4.96 µg/mL (4.60–6.43) and 137.00 µg/mL (110.5–162.00) in the 10-min protocol, 3-min protocol and drop protocol, respectively. The result for the drop protocol was significantly higher than those of both nebulization protocols in NALF (p = 0.039). In serum, the gentamicin concentration was 0.98 µg/mL (0.65–1.53) and 0.25 µg/mL (0.25–0.44) in the 10-min and 3-min protocols, respectively. Gentamicin was not detected in the serum of seven out of ten dogs in the drop protocol, and gentamicin was significantly higher in the 10-min protocol compared to the drop protocol (p = 0.001). This study found that the 10-min, 3-min and drop protocols achieved superior concentrations in NALF compared to the minimum inhibitory concentration for gentamicin-sensitive bacteria, while remaining below the toxic values in blood.