Multistrain probiotics fail to modulate the asthmatic phenotype, respiratory microbiota, and immune responses in cats.

OBJECTIVE: To determine if multistrain probiotics administered to asthmatic cats treated with anti-inflammatory glucocorticoids would attenuate the asthmatic phenotype and beneficially alter respiratory, blood, and oropharyngeal (OP) microbial communities and immune parameters versus placebo. ANIMALS: 13 client-owned asthmatic cats. METHODS: A randomized, blinded, placebo-controlled clinical trial of asthmatic cats receiving anti-inflammatory glucocorticoids with oral multistrain probiotics or placebo assessed owner-perceived improvement and airway eosinophilia at baseline and after 2 weeks of treatment. Bronchoalveolar lavage fluid (BALF), blood, OP, and rectal microbial communities were compared using 16S rRNA amplicon sequencing. Real-time PCR for transcription factors, activation markers and cytokines, and IgA ELISAs were evaluated. Statistical analyses used 2-way repeated-measures ANOVA or permutational ANOVA (significance, P < .05). RESULTS: After treatment, there were no significant differences in owner-perceived clinical signs or mean ± SEM BALF eosinophils between groups. There was a significant decrease in rectal α-diversity but not in α- or ß-diversity in BALF, blood, or OP between groups or over time. There were no significant differences in CD25, FoxP3, GATA, Helios, IL-4, IL-5, IL-10, IL-13, IL-17, IFN-γ mRNA, or serum or BALF IgA between groups or over time. CLINICAL RELEVANCE: In asthmatic cats, oral multistrain probiotics failed to improve owner-perceived signs, reduce airway eosinophilia, modify microbial community composition, or alter assessed immune responses versus placebo or over time. Longer treatment, different probiotic composition or delivery (eg, aerosolized), or larger number of cats would represent the next stages of study.

Breathe easy: inhalational therapy for feline inflammatory airway disease.

PRACTICAL RELEVANCE: Feline inflammatory airway diseases, including (but not limited to) asthma, chronic bronchitis and bronchiectasis, are common and incurable disorders. These diseases require lifelong therapy and may result in substantial morbidity and, in some cases, mortality. Goals of therapy include reduction or resolution of clinical signs and the underlying pathologic processes driving those clinical signs. Inhalational therapy has the advantage of topical delivery of drugs to target tissues at higher doses with fewer systemic effects than oral medications. There are multiple options for delivery devices, and proper selection and training on the use of these devices - including acclimation of the cat to the device - can maximize therapeutic efficacy. AIM: As inhalational therapy is uncommonly used by many veterinarians and owners, this review article provides a foundation on the selection and use of devices and inhalant medications for specific feline inflammatory airway diseases. Cats present a unique challenge with respect to the use of inhalers, and easy-to-follow steps on acclimating them to the devices are provided. The review also discusses the mechanics of inhalational therapy and helps clarify why certain medications, such as albuterol (salbutamol), fluticasone or budesonide, are chosen for certain diseases. The ultimate aim is that the practitioner should feel more comfortable managing common airway diseases in cats. EVIDENCE BASE: In compiling their review, the authors searched the veterinary literature for articles in English that discuss inhalational therapy in cats, and which focus primarily on inhaled glucocorticoids and bronchodilators. While most literature on inhalational therapy in cats is based on experimental feline asthma models, there are some studies demonstrating successful treatment in cats with naturally occurring inflammatory airway disease.

The respiratory microbiota and its impact on health and disease in dogs and cats: A One Health perspective.

Healthy lungs were long thought of as sterile, with presence of bacteria identified by culture representing contamination. Recent advances in metagenomics have refuted this belief by detecting rich, diverse, and complex microbial communities in the healthy lower airways of many species, albeit at low concentrations. Although research has only begun to investigate causality and potential mechanisms, alterations in these microbial communities (known as dysbiosis) have been described in association with inflammatory, infectious, and neoplastic respiratory diseases in humans. Similar studies in dogs and cats are scarce. The microbial communities in the respiratory tract are linked to distant microbial communities such as in the gut (ie, the gut-lung axis), allowing interplay of microbes and microbial products in health and disease. This review summarizes considerations for studying local microbial communities, key features of the respiratory microbiota and its role in the gut-lung axis, current understanding of the healthy respiratory microbiota, and examples of dysbiosis in selected respiratory diseases of dogs and cats.

Videofluoroscopic swallow study abnormalities identify aerodigestive disorders in dogs with respiratory disease versus healthy controls.

BACKGROUND: Aerodigestive diseases (AeroD) pathologically link respiratory and alimentary tracts. Dogs with respiratory signs lacking dysphagia, vomiting, or regurgitation typically do not undergo diagnostic testing that identifies comorbid alimentary disease. A videofluoroscopic swallow study (VFSS) identifies defects in swallowing, reflux, and aspiration. OBJECTIVES/HYPOTHESIS: We hypothesized that dogs with respiratory and no alimentary disease (RESP) would have significantly more abnormal VFSS metrics versus controls (CON). We hypothesized RESP dogs with pulmonary parenchymal disease would have more reflux and higher penetration-aspiration score (PAS) than those with airway disease. ANIMALS: Client-owned dogs: RESP (n = 45) and CON (n = 15) groups. METHODS: Prospectively, all dogs underwent VFSS. The RESP dogs had advanced respiratory diagnostic testing. Eight subjective and 3 objective VFSS metrics (pharyngeal constriction ratio [PCR], PAS, and esophageal transit time [ETT]) were assessed. Fisher's exact test compared differences between groups (presence or absence of VFSS abnormalities). The Mann-Whitney rank sum test was used to compare PCR and PAS. RESULTS: Subjective VFSS abnormalities were present in 34/45 (75%) RESP and 2/15 (13%) CON dogs, with RESP dogs significantly more likely to have VFSS abnormalities (P = .01). No difference in PCR was found between groups. Pathologic PAS was more common in RESP than CON dogs (P = .03). The RESP dogs with airway disease had higher PAS than CON dogs (P = .01) but not RESP dogs with parenchymal disease (P = .25). CONCLUSIONS: Most (75%) RESP dogs had VFSS abnormalities, emphasizing that AeroD are common. The VFSS has value in diagnostic evaluation of respiratory disease.

Ophthalmic viscoelastics commonly used in cataract surgery: A microbiota investigation.

PURPOSE: To survey commonly used, sterile ophthalmic viscoelastic materials used during routine cataract surgery for the presence of bacterial DNA and/or viable bacteria and endotoxin quantification. METHODS: Samples from three different ophthalmic viscoelastic manufacturers and three different production lots per manufacturer were collected for 16 S ribosomal ribonucleic acid (rRNA) sequencing and conventional aerobic and capnophilic bacterial culture. Other samples of viscoelastic material from the same three manufacturers were collected for endotoxin quantification using a commercially available Limulus amebocyte lysate (LAL) assay. Statistical analysis was performed using Sigma Plot 14.0, and R v4.0.2.0. Differences (p ≤ .05) between sample collection sites in total DNA concentration, microbial richness, mean intra-group distances, and endotoxin quantification alongside reagent controls were evaluated. RESULTS: Culture yielded two isolates, identified as Staphylococcus epidermidis and Bacillus megaterium. 16 S rRNA sequencing revealed no differences between brands in richness or overall composition. The most common bacterial DNA detected across all brands was Staphylococcus sp., Cutibacterium sp., Flavobacterium sp., and Lactobacillus sp. A significant difference was found between the median endotoxin concentration between Anvision and Hyvisc® viscoelastic (Anvision: 0.171 EU/mL, Hyvisc®: 0.03 EU/mL; p < .001). CONCLUSIONS: No brand-specific differences in bacterial DNA were detected in the viscoelastic materials. Staphylococcus, Cutibacterium, Flavobacterium, and Lactobacillus were the dominant contributors to the bacterial DNA detected. Although Anvision viscoelastic samples contained significantly more endotoxin than Hyvisc® viscoelastic samples, endotoxin concentrations were below the FDA limit of 0.2 EU/mL for both manufacturers. These data further the understanding of inflammatory outcomes following cataract surgery.

Molecular and microbiological evidence of bacterial contamination of intraocular lenses commonly used in canine cataract surgery.

Inflammatory outcomes, including toxic anterior segment syndrome (TASS) and infectious endophthalmitis, are potentially painful, blinding complications following cataract surgery. In an in vitro pilot study, commercially available, sterile foldable intraocular lenses (IOLs) used during routine canine cataract surgery, and their packaging fluid were surveyed for the presence of bacterial DNA and/or viable (cultivable) bacteria. Swabs from IOLs and packaging fluid from three different veterinary manufacturers and three different production lots/manufacturer were collected for 16S ribosomal ribonucleic acid (rRNA) sequencing. Packaging fluid samples were collected for aerobic/capnophilic bacterial culture. Culture yielded one isolate, identified as Staphylococcus epidermidis. 16S rRNA sequencing revealed distinct brand-specific bacterial DNA profiles, conserved between IOLs and packaging fluid of all production lots within each manufacturer. The dominant taxonomy differentiating each manufacturer was annotated as Staphylococcus sp, and was a 100% match to S. epidermidis. Distinct mixtures of bacterial DNA are present and consistent in IOLs and packaging fluid depending on the manufacturer, and Staphylococcus is the dominant contributor to the bacterial DNA detected. Caralens products had a significantly lower amount of Staphylococcus spp. compared to Anvision and Dioptrix products.

Incidence, clinical signs, and videofluoroscopic swallow study abnormalities associated with airway penetration and aspiration in 100 dogs.

BACKGROUND: Videofluoroscopic swallow studies (VFSS) utilizing penetration-aspiration (P-A) scoring assesses airway protection in people. On VFSS, penetration (ingesta or secretions immediately cranial to the vocal folds) and aspiration (material caudal to the vocal folds) are associated with increased risk of lung injury in people. Penetration-aspiration (P-A) scoring has been validated in animal models, but the incidence of P-A, clinical signs (CS), and dysphagic disorders associated with P-A in dogs are unknown. OBJECTIVES: Using VFSS, identify the incidence of P-A, compare CS between dogs with and without P-A, and identify predisposing dysphagic abnormalities for P-A. ANIMALS: One hundred client-owned dogs. METHODS: Sequential VFSS and associated medical records from dogs presenting to the veterinary teaching hospitals at Auburn University (n = 53) and the University of Missouri (n = 47) were retrospectively reviewed. Statistical comparisons were made using Mann-Whitney tests, one-way analysis of variance (ANOVA) on ranks, multiple linear regression, and Spearman rank order correlation (P < .05). RESULTS: On VFSS, the incidence of pathologic P-A was 39%. No significant differences in CS were found between dogs with or without P-A (P > .05), with 14/39 dogs with P-A presenting without respiratory CS. Pharyngeal (P < .001) and esophageal (P = .009), but not oral-preparatory (P = .2) dysphagia was more common with P-A. Pharyngeal weakness (P < .001) and esophago-oropharyngeal reflux (EOR; P = .05) were independent predictors of P-A and were moderately and weakly positively correlated with P-A score respectively (P < .001, r = 0.489; P = .04, r = 0.201). CONCLUSIONS: Penetration-aspiration occurs in dogs in the absence of respiratory CS (i.e., occult P-A). Dogs with pharyngeal weakness and EOR should be considered at risk for P-A.

Respiratory dysbiosis in cats with spontaneous allergic asthma.

Deviations from a core airway microbiota have been associated with the development and progression of asthma as well as disease severity. Pet cats represent a large animal model for allergic asthma, as they spontaneously develop a disease similar to atopic childhood asthma. This study aimed to describe the lower airway microbiota of asthmatic pet cats and compare it to healthy cats to document respiratory dysbiosis occurring with airway inflammation. We hypothesized that asthmatic cats would have lower airway dysbiosis characterized by a decrease in richness, diversity, and alterations in microbial community composition including identification of possible pathobionts. In the current study, a significant difference in airway microbiota composition was documented between spontaneously asthmatic pet cats and healthy research cats mirroring the finding of dysbiosis in asthmatic humans. Filobacterium and Acinetobacter spp. were identified as predominant taxa in asthmatic cats without documented infection based on standard culture and could represent pathobionts in the lower airways of cats. Mycoplasma felis, a known lower airway pathogen of cats, was identified in 35% of asthmatic but not healthy cats. This article has been published alongside "Temporal changes of the respiratory microbiota as cats transition from health to experimental acute and chronic allergic asthma" (1).

Temporal changes of the respiratory microbiota as cats transition from health to experimental acute and chronic allergic asthma.

In humans, deviation from a core airway microbiota may predispose to development, exacerbation, or progression of asthma. We proposed to describe microbiota changes using 16 rRNA sequencing in samples from the upper and lower airways, and rectal swabs of 8 cats after experimental induction of asthma using Bermuda grass allergen, in acute (6 weeks) and chronic (36 weeks) stages. We hypothesized that asthma induction would decrease richness and diversity and alter microbiota composition and structure in the lower airways, without significantly impacting other sites. After asthma induction, richness decreased in rectal (p = 0.014) and lower airway (p = 0.016) samples. B diversity was significantly different between health and chronic asthma in all sites, and between all time points for lower airways. In healthy lower airways Pseudomonadaceae comprised 80.4 ± 1.3% whereas Sphingobacteriaceae and Xanthobacteraceae predominated (52.4 ± 2.2% and 33.5 ± 2.1%, respectively), and Pseudomonadaceae was absent, in 6/8 cats with chronic asthma. This study provides evidence that experimental induction of asthma leads to dysbiosis in the airways and distant sites in both the acute and chronic stages of disease. This article has been published alongside "Respiratory dysbiosis in cats with spontaneous allergic asthma" (1).

Reversibility of clinical and computed tomographic lesions mimicking pulmonary fibrosis in a young cat.

BACKGROUND: In humans with idiopathic pulmonary fibrosis (IPF), specific thoracic computed tomographic (CT) features in the correct clinical context may be used in lieu of histologic examination. Cats develop an IPF-like condition with similar features to humans. As few cats have invasive lung biopsies, CT has appeal as a surrogate diagnostic, showing features consistent with architectural remodeling supporting "end-stage lung". CASE PRESENTATION: A 1-year-old female spayed Domestic Shorthair cat presenting with progressive respiratory clinical signs and thoracic CT changes (reticular pattern, parenchymal bands, subpleural interstitial thickening, pleural fissure thickening, subpleural lines and regions of increased attenuation with traction bronchiectasis and architectural distortion) consistent with reports of IPF was given a grave prognosis for long-term survival. The cat was treated with prednisolone, fenbendazole, pradofloxacin and clindamycin. Five months later, while still receiving an anti-inflammatory dose of prednisolone, the cat was re-evaluated with owner-reported absent respiratory clinical signs. Thoracic CT demonstrated resolution of lung patterns consistent with fibrosis. CONCLUSIONS: Fibrotic lung disease is irreversible. Despite this cat having compatible progressive respiratory signs and associated lung patterns on thoracic CT scan, these abnormalities resolved with non-specific therapy and time, negating the possibility of IPF. While the cause of the distinct CT lesions that ultimately resolved was not determined, infection was suspected. Experimental Toxocara cati infection shows overlapping CT features as this cat and is considered a treatable disease. Improvement of CT lesions months after experimental heartworm-associated respiratory disease in cats has been documented. Reversibility of lesions suggests inflammation rather than fibrosis was the cause of the thoracic CT lesions. This cat serves as a lesson that although thoracic CT has been advocated as a surrogate for histopathology in people with IPF, additional studies in cats are needed to integrate CT findings with signalment, other clinicopathologic features and therapeutic response before providing a diagnosis or prognosis of fibrotic lung disease.

Bacterial infection in dogs with aspiration pneumonia at 2 tertiary referral practices.

BACKGROUND: In dogs, antimicrobial drugs are widely prescribed for aspiration pneumonia (AP) despite poor documentation of bacterial infection in AP (b-AP) using bronchoalveolar lavage fluid (BALF) analysis. Interpretating discordant cytology and culture results is challenging, contributing to lack of a criterion standard, and highlighting differences between veterinary and human medical criteria for b-AP. OBJECTIVES: Determine how many dogs with AP had BALF collection and differences in diagnosis of b-AP using veterinary vs human medical criteria. Report findings of noninvasive markers (e.g. fever, band neutrophilia, radiographic severity score) in dogs with and without b-AP. ANIMALS: Retrospective cohort study of client-owned dogs (n = 429) with AP at 2 university veterinary hospitals. Twenty-four dogs met enrollment criteria. METHODS: Inclusion criteria were radiographic diagnosis of AP, ≥1 risk factor, CBC findings, and BALF cytology and culture results. Veterinary medical b-AP criteria were cytology findings compatible with sepsis with or without positive culture, or cytology findings not consistent with sepsis and positive culture (≥1.7 × 103  cfu/mL). Human medical b-AP criteria required culture with ≥104  cfu/mL or > 7% cells with intracellular bacteria on cytology. RESULTS: Only 24/429 dogs met all enrollment criteria; 379/429 dogs lacked BALF collection. Diagnosis of b-AP differed using veterinary (79%) vs human (29%) medical criteria. Fever, band neutrophils and high radiographic scores were noted in dogs with and without b-AP. CONCLUSIONS AND CLINICAL IMPORTANCE: Lack of routine BALF collection hampers definitive recognition of bacterial infection in AP. Differences in dogs meeting veterinary vs human medical definitions for b-AP and usefulness of noninvasive markers warrant further study to improve understanding of the role of bacteria in AP.

Comparison of Short- versus Long-Course Antimicrobial Therapy of Uncomplicated Bacterial Pneumonia in Dogs: A Double-Blinded, Placebo-Controlled Pilot Study.

Current treatment for canine bacterial pneumonia relies on protracted courses of antimicrobials (3-6 weeks or more) with recommendations to continue for 1-2 weeks past resolution of all clinical and thoracic radiographic abnormalities. However, in humans, bacterial pneumonia is often treated with 5-10-day courses of antimicrobials, and thoracic radiographs are not considered useful to guide therapeutic duration. The primary study objective was to determine whether a short course of antimicrobials would be sufficient to treat canine bacterial pneumonia. Eight dogs with uncomplicated bacterial pneumonia were enrolled in this randomized, double-blinded, placebo-controlled study comparing clinical and radiographic resolution with differing durations of antimicrobial therapy. Dogs received a course of antimicrobials lasting 10 (A10) or 21 (A21) days. Dogs randomized to the A10 group received placebo for 11 days following antimicrobial therapy. Patients were evaluated at presentation and 10, 30 and 60 days after the initiation of antimicrobials. At 10 days, 6/8 dogs had resolution of both clinical signs and inflammatory leukogram, and 5/8 dogs had improved global radiographic scores. After 60 days, clinical and hematologic resolution of pneumonia was noted in all dogs regardless of antimicrobial therapy duration; however, 3/8 dogs had persistent radiographic lesions. Thoracic radiographs do not appear to be a reliable marker to guide antimicrobial therapy in canine bacterial pneumonia as radiographic lesions may lag or persist despite clinical cure. This pilot study suggests a 10-day course of antimicrobials may be sufficient to treat uncomplicated canine bacterial pneumonia.

Hirudotherapy (medicinal leeches) for treatment of upper airway obstruction in a dog.

OBJECTIVE: To describe upper airway obstruction (UAO) in a dog treated with medicinal leeches (hirudotherapy) as an ancillary therapy to hasten recovery. CASE SUMMARY: A 10-month-old neutered female Mastiff presented for acute respiratory distress. On admission, the dog was tachycardic, cyanotic, and orthopneic; stridor was audible. A 10-cm soft tissue swelling in the right ventral cervical region and bruising around the rostral mandible were noted. At the time of endotracheal intubation, the trachea was deviated to the right as a consequence of severe soft tissue swelling that was contiguous with the sublingual hematoma and cervical region, causing loss of visualization of the arytenoids. A computed tomography with contrast scan of the head, neck, and thorax was performed, showing severe soft tissue swelling of the tongue, obliteration of the common pharyngeal/laryngeal regions from suspected hemorrhage, and rightward displacement of pharynx, larynx, and proximal trachea. Marked diffuse bronchial/bronchiolar thickening associated with bronchiolectasis and diffuse opacification of the pulmonary parenchyma with regions of consolidation were noted. The dog was minimally hypercoagulable on thromboelastography. The imaging results together with results of bronchoalveolar lavage cytology supported a comorbidity of eosinophilic bronchopneumopathy. Intubation was maintained with infusions of propofol and fentanyl, with minimal changes in oropharyngeal swelling within the first 18 hours of treatment. Medicinal leeches were then applied to the sublingual and cervical regions. There was continued slow bleeding from the sites of leech detachment, and the dog was able to be extubated at 44 hours, followed by hospital discharge. NEW/UNIQUE INFORMATION PROVIDED: Leeches are utilized in human medicine for treatment of UAO. Although UAO from hemorrhage has been described in dogs, this is the first report of medicinal leeches (Hirudo verbana) as complementary treatment for sublingual hematoma that contributed to UAO.

Proteomic Characterization of Canine Gastric Fluid by Liquid Chromatography-Mass Spectrometry for Development of Protein Biomarkers in Regurgitation, Vomiting, and Cough.

Reflux and aspiration in people cause and exacerbate respiratory diseases in the absence of gastrointestinal signs. Protein biomarkers in humans detect extraesophageal reflux (EER) from oropharyngeal (OP) and bronchoalveloar lavage samples. Reflux likely contributes to respiratory disease in dogs. The objectives of this study were to analyze the canine gastric fluid (GF) proteome and compare this to the OP proteome in normal, vomiting/regurgitating, and coughing dogs to identify biomarkers for EER/aspiration. Twenty-three client-owned dogs were enrolled. Canine GF samples (n = 5) and OP swabs in normal (n = 6), vomiting/regurgitating (n = 7), and coughing (n = 5) dogs were within 2 weeks of sample collection. Protein digests were analyzed by liquid chromatography-mass spectrometry. Differential abundance (DA) of proteins between groups was evaluated by Fisher's exact test with p < 0.0004 significance level after correction for multiple comparisons. DA was found between all groups (p < 0.0001): GF vs. normal (n = 130 proteins), coughing vs. normal (n = 22 proteins), and vomiting/regurgitating vs. normal (n = 20 proteins). Protein abundance was highly variable between dogs. Gastrointestinal-specific proteins were found in OP swabs from vomiting/regurgitating and coughing dogs but not from healthy dogs. In conclusion, the proteomic composition of the OP varies between health and disease. The presence of gastrointestinal-specific proteins in OP of coughing dogs may suggest reflux and/or aspiration as contributing factors. The variable protein abundance warrants investigation into biomarker panels.

Lower airway collapse: Revisiting the definition and clinicopathologic features of canine bronchomalacia.

Bronchomalacia (BM) is an inconsistently defined term in dogs, impairing understanding of clinical presentation, therapeutic response and prognosis. Herein the authors propose to clarify the definition of canine bronchomalacia (CBM) as regional to diffuse dynamic airway collapse of segmental and/or subsegmental bronchi with associated clinical signs due to airflow limitation. In contrast to tracheal collapse, mainstem bronchial collapse, and in some cases lobar collapse, CBM requires advanced imaging. Common co-morbid conditions (e.g., chronic bronchitis, mitral valve degenerative disease, etc.) should be identified during a comprehensive diagnostic evaluation. Current empiric treatments advocated in absence of clinical trials documenting efficacy in the dog warrant evaluation, as some (e.g., bronchodilators) may have detrimental effects in certain types of airway collapse in humans. There is no direct treatment for CBM, as defined above, but non-specific therapies and targeted treatment of co-morbid disease may improve clinical signs and quality of life. In this manuscript, the authors provide a review of the different types of airway collapse focusing on CBM, reviewing their definition and etiology, proposing a classification scheme, and discussing clinical signs, diagnostic testing, and treatment. Future studies should focus on both improving understanding of the etiology and natural disease progression of CBM and treatment trials.

Evaluation of Healthy Canine Conjunctival, Periocular Haired Skin, and Nasal Microbiota Compared to Conjunctival Culture.

Next-generation sequencing (NGS) methods have been used to identify a diverse ocular surface (OS) microbiota in humans. These results have highlighted limitations in microbial detection via traditional culture-based techniques. The OS has mechanisms such as tear film and mechanical blinking, which may aid in preventing adherence and colonization of microbes, suggesting that only low populations of microbes may reside on the OS. Additionally, closely related tissues to the OS are exposed to a similar array of microbes, but demonstrate different defense mechanisms. Information regarding concordance of microbial communities of the OS and nearby tissues is lacking. Our study purposes were to (1) characterize the conjunctival microbiota of healthy dogs, (2) compare the conjunctival microbiota to the periocular haired skin and distal nose, and (3) compare the bacteria identified by culture to NGS of the healthy canine conjunctiva. Here, NGS was used to evaluate samples from 25 healthy adult dogs of the conjunctiva, periocular haired skin, and distal nose. Additional samples were collected from each dog for traditional conjunctival culture. The 16S rRNA gene amplicon libraries were evaluated for coverage, relative abundance, richness, and diversity. Site-dependent similarities evaluated using principal coordinate analysis (PCoA) and PERMANOVA demonstrated relatedness in community compositions between sites. The conjunctiva of healthy dogs yielded a rich and diverse microbiota based on NGS. While some regional continuity was noted, microbial communities of the conjunctiva, periocular haired skin, and nose were significantly different from each other. Comparatively, traditional culture markedly underestimated the number of bacterial taxa present on the healthy canine OS. Findings suggest similarities in nasal and conjunctival microbial communities, which may be a result of similarities in mucosal immunity and anatomic connection via the nasolacrimal system. Further investigation using NGS into changes of the composition of bacterial communities in disease is warranted.

Detection of silent reflux events by nuclear scintigraphy in healthy dogs.

BACKGROUND: Reflux and aspiration in people are associated with respiratory disease, whereas approximately 50% of healthy adults microaspirate without apparent consequence. In dogs, analogous information is lacking. HYPOTHESIS: Healthy dogs commonly have gastroesophageal reflux and a proportion of these dogs will have laryngopharyngeal reflux with silent aspiration. ANIMALS: Twelve healthy, client-owned dogs. METHODS: Prospective study: Dogs were free-fed a meal containing (111 MBq) colloidal 99 m-technetium phytate. Dynamic-scans were performed 5 and 30 minutes postingestion. Time-activity curves, reflux margination, volume, frequency, and duration were evaluated over 7 regions of interest in dorsal ± left-lateral recumbency. Static scans (dorsal recumbency) were performed 2 and 18 hours postfeeding to detect aspiration. Reflux and aspiration were defined as counts ≥200% background activity ± decreased gastric counts. Between-group comparisons were performed by Wilcoxon rank-sum test or one-way ANOVA on ranks with significance of P < .05. RESULTS: In this study, reflux of variable magnitude was detected in 12/12 dogs. No significant differences in outcome parameters were detected with recumbency (P > .05). Margination to the pharynx and proximal, middle, and distal esophagus was identified in 5/12, 2/12, 3/12, and 2/12 dogs, respectively. Median (IQR) reflux frequency and duration were 2 events/5 minutes (1-3.3 events/5 minutes) and 6 seconds (4-9 seconds) respectively. No dog had detectable aspiration. CONCLUSIONS AND CLINICAL IMPORTANCE: Nuclear scintigraphy can document reflux in dogs. Reflux, but not aspiration, is common in healthy dogs and must be considered when interpreting results in clinically affected dogs.

Serum allergen-specific IgE reactivity: is there an association with clinical severity and airway eosinophilia in asthmatic cats?

OBJECTIVES: The aim of this study was to evaluate the results of serum allergen-specific IgE testing in cats with a clinical diagnosis of asthma and to determine if the number of allergens with positive IgE reactivity and magnitude of positive IgE responses would be associated with the severity of clinical signs or airway eosinophilia. METHODS: Medical records from 2008 to 2018 were retrospectively reviewed. Inclusion required a diagnosis of feline asthma based on consistent clinicopathologic features and bronchoalveolar lavage (BAL) cytology with >10% eosinophils; additionally, cats needed to have the results of serum allergen-specific IgE tests. RESULTS: Eighteen cases satisfied the inclusion criteria. Median age was 5 years and the most common presenting clinical sign was cough (n = 10/18). Most cats lived exclusively indoors (n = 13/18). The median percentage of BAL eosinophils was 47%. Serum allergen-specific IgE testing supported an underlying allergic etiology in 14/18 (78%) cats, with all but one having polysensitization. The severity of clinical signs and magnitude of airway eosinophilia did not correlate with the degree of positive IgE reactivity. CONCLUSIONS AND RELEVANCE: This study identified a strong association between the identification of allergen-specific IgE and cats with asthma, and the majority of these cats were polysensitized. However, larger numbers of allergens with positive IgE reactivity or magnitude of IgE reactivity were not significantly associated with clinical severity or airway eosinophilia. Knowledge of positive allergen-specific IgE results could guide allergen avoidance, regardless of the magnitude of IgE reactivity.

Respiratory dysbiosis and population-wide temporal dynamics in canine chronic bronchitis and non-inflammatory respiratory disease.

The lungs of people and companion animals are now recognized to harbor diverse, low biomass bacterial communities. While these communities are difficult to characterize using culture-based approaches, targeted molecular methods such as 16S rRNA amplicon sequencing can do so using DNA extracted from samples such as bronchoalveolar lavage fluid (BALF). Previous studies identified a surprisingly uniform composition of the microbiota in the lungs of healthy research dogs living in a controlled environment, however there are no reports of the lung microbiota of client-owned dogs. Moreover, compositional changes in the lung microbiota depending on disease status have been reported in people, suggesting that similar events may occur in dogs, a species subject to several respiratory disease mechanisms analogous to those seen in people. To address these knowledge gaps, BALF samples from client-owned dogs presenting to the University of Missouri Veterinary Health Center for respiratory signs between 2014 and 2017 were processed for and subjected to 16S rRNA sequencing. Based on specific diagnostic criteria, dogs were categorized as Chronic Bronchitis (CB, n = 53) or non-CB (n = 11). Community structure was compared between groups, as well as to historical data from healthy research dogs (n = 16) of a uniform breed and environment. The lung microbiota detected in all client-owned dogs was markedly different in composition from that previously detected in research dogs and contained increased relative abundance of multiple canine fecal and environmental bacteria, likely due to aspiration associated with their clinical signs. While inter-sample diversity differed significantly between samples from CB and non-CB dogs, the variability within both groups made it difficult to discern reproducible bacterial classifiers of disease. During subsequent analyses to identify other sources of variability within the data however, population-wide temporal dynamics in community structure were observed, with substantial changes occurring in late 2015 and again in early 2017. A review of regional climate data indicated that the first change occurred during a historically warm and wet period, suggesting that changes in environmental conditions may be associated with changes in the respiratory microbiota in the context of respiratory disease. As the lung microbiota in humans and other animals is believed to result from repetitive micro-aspirations during health and in certain disease states associated with dyspnea and laryngeal dysfunction, these data support the increased colonization of the lower airways during compromised airway function, and the potential for temporal effects due to putative factors such as climate.

Thoracic computed tomographic interpretation for clinicians to aid in the diagnosis of dogs and cats with respiratory disease.

In humans, high-resolution computed tomography (CT) is a key diagnostic modality for pulmonary disorders. Its success likely lies in excellent correlation of lung diseases with associated subgross anatomic changes, as assessed by histopathology, and because of a multidisciplinary approach between clinicians, radiologists and pathologists. Although thoracic CT studies have been performed in dogs and cats for nearly three decades, there is a lack of uniformity in both protocols for acquisition and in terminology used to describe lesions. Importantly, terms such as a bronchial, interstitial, and alveolar patterns are inappropriate descriptors for canine and feline thoracic CT imaging changes; instead, lung patterns should be classified as increased or decreased attenuation, nodular patterns, and linear patterns, with specific vocabulary to describe subtypes of lesions. In this manuscript, the authors provide an overview of basic CT principles, strategies to optimize and acquire high-quality diagnostic studies (inclusive of paired inspiratory and expiratory series, contrast and triphasic angiography) and provide a roadmap for systematic interpretation of thoracic CT images.