Feline Respiratory Disease Research Articles

Feline respiratory disease complex: insights into the role of viral and bacterial co-infections.

Feline respiratory disease complex (FRDC) is a highly prevalent syndrome in cats that often result in fatal outcomes. FRDC etiology is complex, and often, multiple viral and bacterial pathogens are simultaneously associated with disease causation. There is limited information about the role of co-infections in pathogenesis and the current prevalence of pathogens in North America. We aimed to conduct a study using technical advances in molecular diagnosis and statistical modeling analysis to elucidate the occurrence of pathogens and how co-infections affect disease severity. We attained information from three diagnostic laboratories in North America regarding the occurrence of Bordetella bronchiseptica, Chlamydia felis, Mycoplasma, Felid alphaherpesvirus 1 (FeHV-1), feline calicivirus (FCV), and influenza A, along with age, seasonality, sex, and clinical signs. We also evaluated the role of co-infections in disease severity. These pathogens were also investigated in clinically normal cats (control). The most detected pathogens were Mycoplasma, FCV, and FeHV-1. Most pathogens were detected in the control group, highlighting the challenge of interpreting positive testing results. Co-infections of Mycoplasma and FCV, as well as Mycoplasma and FeHV-1, were important predictors of disease severity. Age, sex, and season had a minor impact on pathogen occurrence. This study provides new insights into FRDC and underlines the relevance of diagnostic panels to screen for a range of pathogens, providing knowledge for timely diagnosis and therapeutic interventions.

Spectrum detection and analysis of the epidemiological characteristics of infectious pathogens in the feline respiratory tract.

Our study was designed to investigate the original spectrum of feline respiratory tract infection and to provide a scientific basis for the clinical diagnosis and treatment of feline respiratory infections and for precise prevention and control measures. A total of 400 cats with upper respiratory tract infections from animal hospitals in 12 provinces in China were examined from November 2022 to October 2023 to investigate the epidemiology of feline calicivirus (FCV), feline herpes virus type 1 (FHV-1), influenza A virus (IAV), Mycoplasma felis, Chlamydia felis, and Bordetella bronchiseptica through loop-mediated isothermal amplification (LAMP) with microfluidic chip detection. The results showed that 396 of the 400 samples tested were positive for at least one of these pathogens, with an overall detection rate of 99.00%. The detection rates were as follows: FCV, 36.00% (144/400); M. felis, 34.00% (136/400); FHV-1, 21.50% (86/400); C. felis, 15.75% (63/400); B. b, 13.00% (52/400); IAV, 4.50% (18/400). There were no statistically significant differences in the detection rates of respiratory pathogens between different sexes, ages, seasons, breeds, or regions (P > 0.05). There were 88 mixed infections, giving a total mixed infection rate of 22.00% (88/400). It is worth noting that the detection rate of FCV at different ages and of FHV-1 in different sexes showed significant differences (P < 0.05). The highest rate of FCV infection was found in animals that were 1 to 2 years old, and the rate of FHV-1 infection in male cats was higher than that in female cats. The results showed that the spectrum of feline respiratory pathogens is complex, with diverse epidemiological characteristics and mixed infections, and some differences among different respiratory pathogens were found with regard to the sex, age, and breed of the cat. Studies should be continued to provide a scientific basis for precise prevention and control of feline respiratory diseases.

Retrospective study of 540 cats with respiratory diseases in Japan (2003-2020).

Few epidemiological studies on respiratory medicine and the relationship between clinical signs and various respiratory diseases in cats have been reported. This retrospective study aimed to investigate the prevalence and breed predisposition to feline respiratory diseases in Japan and determine the association between clinical signs, duration and type of respiratory diseases. The medical records of cats with feline respiratory diseases were examined to obtain information on age, sex, breed, final diagnosis, clinical signs and duration. The odds ratios (ORs) and 95% confidence intervals were calculated to evaluate breed predispositions. Mann-Whitney U, Kruskal-Wallis and Dunn's tests were used to assess the duration of clinical signs. This study included 540 cats with 615 respiratory diagnoses. The American Shorthair breed was predisposed to bronchopneumonia (BP; OR: 5.0) and pulmonary tumour (PT; OR: 3.6), while the Russian Blue breed exhibited a predisposition to inflammatory lower airway diseases (OR: 3.4), BP (OR: 6.1) and interstitial lung diseases (OR: 11.1). Similarly, the Scottish Fold breed displayed predisposition to PTs (OR: 5.8). The duration of clinical signs among nasal diseases, nasopharyngeal diseases and lower tracheal/bronchial and pulmonary diseases differed significantly (p = 0.001, p = 0.012, p < 0.0001, respectively). The results suggest that some popular breeds in Japan are predisposed to feline respiratory diseases, especially the American Shorthair, Russian Blue and Scottish Fold breeds. The characteristics of occurrence, clinical signs and duration of each disease will aid in diagnosing, treating, preventing and elucidating the pathophysiology of feline respiratory disease.

Development and validation of multiplex one-step qPCR/RT-qPCR assays for simultaneous detection of SARS-CoV-2 and pathogens associated with feline respiratory disease complex.

Feline respiratory disease complex (FRDC) is caused by a wide range of viral and bacterial pathogens. Both Influenza A virus (IAV) and Severe Acute Respiratory Syndrome Coronavirus-2 (SARS-CoV-2) also induce respiratory diseases in cats. Two one-step multiplex qPCR/RT-qPCR assays were developed and validated: FRA_1 (Feline respiratory assay 1) for the detection of four viral targets and FRA_2 for the detection of three bacteria associated with FRDC. Both multiplex assays demonstrated high specificity, efficiency (93.51%-107.8%), linearity (> 0.998), analytical sensitivity (≤ 15 genome copies/μl), repeatability (coefficient of variation [CV] < 5%), and reproducibility (CV < 6%). Among the 63 clinical specimens collected from FRDC-suspected cats, 92.1% were positive for at least one pathogen and co-infection was detected in 57.1% of samples. Mycoplasma felis (61.9%) was the most found pathogen, followed by feline herpesvirus-1 (30.2%), Chlamydia felis (28.7%) and feline calicivirus (27.0%). SARS-CoV-2 was detected in two specimens. In summary, this new panel of qPCR/RT-qPCR assays constitutes a useful and reliable tool for the rapid detection of SARS-CoV-2 and viral and bacterial pathogens associated with FRDC in cats.

Metastrongyloid Infection with Aelurostrongylus abstrusus, Troglostrongylus brevior, Oslerus rostratus and Angiostrongylus chabaudi in Feral Cats from the Canary Islands (Spain)

Lungworms are a major cause of feline respiratory disease, frequently underdiagnosed due to its presentation of symptoms being similar to that of other feline respiratory pathologies. Epidemiological data about these nematodes are scarce in the Canary Islands (Spain). Given the veterinary importance of these parasites, the aim of the present study was to improve the current epidemiological knowledge of the lungworm species that could be affecting feral cats in this archipelago. A total of 29 feral cats from La Gomera were analyzed. The respiratory tract of each animal was inspected and the nematodes obtained were identified by morphological keys and molecular techniques. Metastrongylids were detected to be widely distributed throughout the island with a prevalence of 55.2% (16/29). The species Aelurostrongylus abstrusus, Troglostrongylus brevior, Oslerus rostratus and Angiostrongylus chabaudi were identified. Also, coinfections with A. chabaudi and O. rostratus were detected in two animals. The present study shows a high diversity of lungworms in feral cats in La Gomera, with the first report of A. chabaudi and T. brevior for the Canary Archipelago and the first citation of A. chabaudi in cats for Spain. The wide distribution and high prevalence found in this study indicate a high risk of exposure to pulmonary infections in cats.

Feline respiratory disease. Part 2: management of the common causes

Background: Chronic nasal discharge and sneezing are common problems in cats and can be among the most frustrating conditions we have to deal with. While conditions that cause unilateral signs can usually be diagnosed and often effectively treated, the most common cause of bilateral nasal discharge is chronic rhinosinusitis, a lifelong condition that can be managed with varying degrees of success but will rarely resolve.Aim of the article: This article, the second in a two‐part series, reviews the treatment options and current approaches to managing common causes of feline respiratory disease. The first article, published in last month's In Practice, covered the common causes of nasal discharge in the UK cat population and the diagnostic investigations that can assist in reaching a definitive diagnosis.

Feline respiratory disease. Part 1: common causes and reaching a diagnosis

Background: Chronic nasal discharge and sneezing are common presenting signs in cats and can be caused by a number of underlying disorders, some of which can be effectively treated but others of which are among the most frustrating conditions we have to deal with. Secondary bacterial infections are a common complication whatever the primary aetiology, so there is often improvement in response to a course of antibiotics, but it is frequently only a temporary fix. Reaching a definitive diagnosis at an early stage identifies those conditions that can be treated effectively and leads to a better understanding of the prognosis for those that can't. Given the similarity in clinical signs for all underlying causes, reaching a diagnosis will require investigation under anaesthesia in most cases, but investigations can often be undertaken in first‐opinion practice without the need for referral.Aim of the article: This article, the first in a two‐part series, will review common causes of nasal discharge in the UK cat population and the diagnostic investigations that can assist in reaching a definitive diagnosis. The second article, to be published in a subsequent issue of In Practice, will review current approaches to managing these conditions.

Development of immortalized feline respiratory epithelial cells in an air-liquid-interface culture system for feline herpesvirus-1 study

Feline herpesvirus-1 (FHV-1) is responsible for approximately 50% of diagnosed viral upper respiratory tract disease in cats. The virus infects and replicates in the epithelial cells located in upper respiratory tract. Commercial vaccines do not protect cats from the infection itself or development of latency. Previously, our lab developed a cell culture model using primary feline respiratory epithelial cells (pFRECs) to study respiratory innate immunity to FHV-1 and FHV-1 deletion mutants. However, the numbers of pFRECs that can be obtained per cat is limited. To improve the usage of respiratory epithelial 3D cultures in FHV-1 research, the present study immortalized feline respiratory epithelial cells (iFRECs) and characterized them morphologically and immunologically and evaluated the response to FHV-1 infection. Immortalization was achieved by transduction with Lenti-SV40T and Lenti-HPV E6/E7. Immortalized FRECs could be successfully subcultured for >20 passages, with positive gene expression of SV40T and HPV E6/E7. Immortalized FRECs expressed similar innate immunity-associated genes compared to pFRECs, including genes of Toll-like receptors (TLR1–9), interferon induced genes (OAS1, OAS3, IFI44, IFITM1, IFIT1), chemokines (CCL2, CCL3, CXCL8), pro-inflammatory and regulatory cytokines (IL-6, IL-4, IL-5, IL-12, and IL-18), and antimicrobials (DEFβ10, DEFβ4B). Finally, FHV-1 inoculation resulted in characteristic cytopathic effects starting at 24 hpi, with more than 80% cells detached and lysed by 72 hpi. Overall FHV-1 growth kinetics in iFRECs resembled the kinetics observed in pFRECs. In conclusion, we demonstrated that iFRECs are a useful tool to study feline respiratory disease including but not limited to FHV-1.

Occurrence of Aelurostrongylus abstrusus in domestic cats in Vilhena, Rondônia, Brazil.

Aelurostrongylosis, caused by the metastrongylid nematode Aelurostrongylus abstrusus, is an underestimated feline respiratory disease. Cats infected by A. abstrusus may show subclinical to severe clinical signs. Aelurostrongylus abstrusus has a worldwide distribution. Nevertheless, studies on this parasite in Brazil are scarce, and most have been conducted in the southern regions. This study investigated the occurrence of A. abstrusus in cats in Vilhena, Rondônia, Brazil, from April 2020 to February 2021. Three consecutive individual fecal samples from 101 cats were examined using Baermann and Hoffman tests. Two cats (1.98%) scored positive for A. abstrusus, one with the Baermann examination, and one with the Hoffman technique. No other lungworms were retrieved. The clinicopathological and epizootiological implications are described and discussed.

Поширення та особливості клінічного прояву ринотрахеїту котів у м. Харкові

Feline respiratory infectious diseases have spread to many countries around the world. The isolation of a specific pathogen and its identification are of great importance. It is also important for the use of specific agents for the treatment and prevention of these diseases. In 2019-2020 the studies at the private veterinary clinic «Aibolit» in Kharkiv were conducted in the conditions of private breeding cattery for cats in the city and using the equipment of the educational - scientific laboratory of molecular - genetic research methods at KHZVA. Materials for research were cats of different breeds and sex-age groups with clinical signs of respiratory diseases, as well as biomaterials from them (blood and nasal discharge), which were studied both by virological methods and PCR. The nosological profile of respiratory infectious diseases of cats in Kharkiv is formed by 3 nosological units. In 24% of cases, the clinical manifestations of rhinotracheitis in cats were caused by the association of two or three pathogens (calicivirus, herpesvirus and chlamydia). The herpes viruses accounted for 33.1% of the total samples of cats’ biomaterials that were examined. From animals with infection using PCR herpes virus was isolated in 83.8% of cases. In 55 cases (42.6%) this virus was the only pathogen that was detected. The analysis of the disease of cats taking into account their age showed that rhinotracheitis was more often affected by young cats at the age of 1.5-3.5 months to 5.5 years and older. Cats that were kept individually and in groups were ill. Cats of certain breeds were sick. Cases of the disease were recorded more often in spring and autumn. The disease proceeded in respiratory, conjunctival and less often in genital forms. The main pathway to isolate the rhinotracheitis pathogen into the external environment was respiratory, with outflows from the nasal cavity of animals, where they were detected in an amount of 2.03 ± 0.12 lg TCD 50 / ml - 2.05 ± 0.16 lg TCD 50 / ml. (by age group) even with latent infection. The pathogen was isolated in 38,4% of cats with clinical manifestations of the disease using PCR. In 23.8% of cases the herpes virus was isolated as the only pathogen.

Mucoid Pseudomonas aeruginosa infection in a cat with severe chronic rhinosinusitis

A 6-year-old male neutered Bengal cat was presented to the University of Wisconsin Veterinary Care Hospital with a history of severe chronic rhinitis that was unresolved from kittenhood. In weeks prior to presentation, the cat's upper respiratory signs had significantly worsened and a left-sided facial swelling overlying the left frontal sinus was noted. Skull computed tomography, rhinoscopy, bilateral nasal biopsies, bacterial and fungal cultures of fluid from the left frontal sinus, and cryptococcal fungal antigen testing were performed. The cat was diagnosed with severe chronic rhinosinusitis and determined to have an infection with a mucoid variant of Pseudomonas aeruginosa (Paeruginosa). This case highlights an atypical cytomorphologic appearance of the well-known bacterial pathogen, Paeruginosa, an appearance that could be confused cytologically with other microorganisms, such as septate fungi. Mucoid variants of Paeruginosa are often associated with progressive lung or airway disease in people with cystic fibrosis and have not been previously documented in feline respiratory tract disease. This report also presents a brief review of chronic rhinosinusitis (CRS) in cats and describes a novel interventional treatment approach to feline CRS via sinusotomy and sinus flushing for severely affected cats.

Identification of a novel parvovirus in domestic cats

A novel protoparvovirus species was identified in domestic cats. The virus was distantly related to the well-known feline (feline panleukopenia virus) and canine (canine parvovirus type 2) parvoviruses, sharing low nucleotide identities in the capsid protein 2 (less than 43%). The virus was genetically similar (100% at the nucleotide level) to a newly identified canine protoparvovirus, genetically related to human bufaviruses. The feline bufavirus appeared as a common element of the feline virome, especially in juvenile cats, with an overall prevalence of 9.2%. The virus was more common in respiratory samples (9.5%–12.2%) than in enteric samples of cats (2.2%). The role of bufaviruses in the etiology of feline respiratory disease complex, either as a primary or a secondary agents, should be defined.

Feline Troglostrongylosis: Current Epizootiology, Clinical Features, and Therapeutic Options.

Parasitic bronchopneumonia plays an important role in feline respiratory medicine, thus it is receiving growing attention by researchers and practitioners. In recent years, Troglostrongylus brevior, a lungworm usually infecting wild felids, has been recognized as an agent of the lower respiratory tract in domestic cats. In particular, as a likely consequence of a spill-over from wild reservoirs (e.g., the European wildcat), T. brevior infection is increasingly reported in cats from Mediterranean and Balkan countries. This parasitic nematode has an indirect life cycle, and its biology overlaps that of the better known “cat lungworm” Aelurostrongylus abstrusus. In fact, cases of co-infections caused by both lungworms are not infrequent in domestic cats. Knowledge on clinical features of troglostrongylosis is still incomplete. Available data indicates that clinical signs and radiographic evidence are severe especially in kittens and young cats, are non-specific and often overlap with those of other feline respiratory diseases, such as feline bronchial disease/asthma, or infectious pneumonia. These characteristics make a definitive diagnosis of troglostrongylosis challenging, this disease requires a timely ancillary therapy and an appropriate anthelminthic treatment. As feline troglostrongylosis is an emerging parasitic disease of domestic cats, it should be included in differential diagnosis for lower respiratory tract disease in cats from regions where this parasite is present but also where it is unexpected. This article reviews current knowledge on the pathogenic role of T. brevior in domestic cats and resulting respiratory illness, with a special focus on clinical aspects, diagnosis, and management of the disease.

Not feline fine

Abstract Management of feline respiratory disease doesn’t need to be a hassle for owner or vet, as delegates at BSAVA Congress will discover.

Feline respiratory disease: what is the role of Mycoplasma species?

Non-hemotropic Mycoplasma species are frequently implicated in cases of respiratory disease, and also conjunctivitis, in cats. Mycoplasma species are considered commensal bacteria of the conjunctiva and the upper respiratory tract of cats, and hence their role as a primary pathogen is difficult to determine. These organisms certainly appear to play a significant role as a secondary pathogen in the upper airways, and there is increasing evidence that in some animals they may represent a primary infection. However, mycoplasmas have not been found in the lower airways of clinically healthy cats - suggesting that, when present, they likely represent a pathologic process. Diagnostic challenges exist as well; Mycoplasma species are not typically identified via cytology due to their small size, and culture of these organisms requires special media and handling. Although PCR has improved identification and allowed for speciation, conflicting culture and PCR results can create a dilemma regarding the clinical relevance of infection. This article draws on original research and case reports to provide information about the role of Mycoplasma species in the feline upper and lower respiratory tract, diagnostic methods and associated challenges, and treatment options. The goal is to provide small animal practitioners with a current and organized review of the often-conflicting literature regarding the role of Mycoplasma species in feline respiratory infections.

Nasopharyngeal disease in cats: 1. Diagnostic investigation.

Nasal discharge, sneezing and upper respiratory noise are frequent presenting signs in feline practice. The small nasal cavity of the cat can make visualisation of lesions challenging. In addition, investigations may identify only secondary complications of a disease process, rather than the initial aetiological agent. Nasopharyngeal disease is a worldwide problem. However, fungal disease shows regional variations in prevalence. This review, aimed at general practitioners as well as those undertaking more specialist investigations in feline respiratory disease, aims to provide practical guidance on the approach necessary to obtain a diagnosis in cats with nasopharyngeal disease. It should also help to explain why a specific diagnosis may not always be possible. While access to endoscopy and computed tomography is advantageous, extensive information can be gained from equipment readily available in all practices. The information presented in this article is based on peer-reviewed publications and the clinical experience of the authors.

Pandemic and Seasonal Human Influenza Virus Infections in Domestic Cats: Prevalence, Association with Respiratory Disease, and Seasonality Patterns

Domestic cats have several features that make them ideal vehicles for interspecies transmission of influenza viruses; however, they have been largely overlooked as potential reservoirs or bridging hosts. In this study, we conducted serological surveillance to assess the prevalence of novel pandemic H1N1 as well as seasonal human influenza virus infections in domestic cats in Ohio. Four hundred serum samples collected from domestic cats (September 2009 to September 2010) were tested using a hemagglutination inhibition (HI) test. The seroprevalences of pandemic H1N1, seasonal H1N1, and H3N2 were 22.5%, 33%, and 43.5%, respectively. In addition, a significant association between clinical feline respiratory disease and influenza virus infection was documented. In this sample of cats, the prevalence of pandemic H1N1 did not follow the seasonality pattern of seasonal H1N1 or H3N2 influenza, similar to observations in humans. Pandemic H1N1 seroprevalence did not vary in relation to ambient temperature changes, while the seroprevalence of seasonal H3N2 and H1N1 influenza viruses increased with the decline of ambient temperature. Our results highlight the high prevalence of influenza virus infection in domestic cats, a seasonality pattern of influenza virus infection comparable to that in humans, and an association of infection with clinical respiratory disease.

Terapia floral em gatos domésticos (Felis catus, Linnaeus, 1758) portadores do complexo da doença respiratória felina: estudo clínico e hematológico

A terapia floral é considerada, atualmente, prática médica alternativa utilizada em diversas situações clínicas, constituindo possibilidade a mais de prevenção e cura de muitas doenças de natureza física e emocional. Este estudo objetivou pesquisar o efeito das essências do Sistema Brasileiro de Florais Compostos de Joel Aleixo num mesmo grupo de gatos domésticos com sinais clínicos sugestivos de Doença Respiratória Felina (DRF), tratados em diferentes momentos (M0, M1, M2, M3). Foram utilizados 20 gatos domésticos, de ambos os sexos, sem raça definida, com idade média de 5,63 ± 3,02 anos criados em gatil na UFRPE. Os animais foram submetidos ao tratamento com os florais por via oral em duas etapas. Na primeira etapa com os florais Desintus Total e Helminthus Total por 14 dias, e na segunda etapa com os florais Antibius e Regius por 28 dias. Os resultados observados, quanto aos aspectos clínicos, foram redução de secreção nasal, secreção ocular e estertores pulmonares; desaparecimento de sinais clínicos como fezes alteradas, úlceras na cavidade oral, pêlos eriçados e permanência da hipertrofia dos linfonodos. Quanto aos aspectos hematológicos houve interferência nas variáveis relacionadas ao hemograma (hemoglobina, VCM, CHCM, leucócitos, linfócitos e monócitos). Conclui-se que a terapia floral mostrou-se eficaz em gatos domésticos com sinais sugestivos de DRF criados nas mesmas condições de manejo.

Aelurostrongylus abstrusus in a feline colony from central Italy: clinical features, diagnostic procedures and molecular characterization

Clinical features and conventional and molecular diagnostic procedures have been investigated and evaluated for the infection caused by the lungworm Aelurostrongylus abstrusus (Nematoda, Strongylida). Individual fecal samples from all cats living in a colony with suspected lungworm infection underwent coprological flotation with sugar and zinc sulfate solution and the Baermann migration method. Also, pharyngeal swabs collected for each animal were subjected to a diagnostic nested PCR assay specific for a region internal to the ribosomal Internal Transcribed Spacer 2 of A. abstrusus. Eighteen animals were positive at the Baermann method, while 12 and ten out of them were negative when feces were subjected to the flotation with sugar and zinc sulfate solution, respectively. The nested PCR assay yielded positive results when using the pharyngeal swabs from the 18 coprologically positive cats and from six more cats which were coprologically negative, thus indicating an overall infection rate of 24.4%. Twenty-two out of 24 infected cats showed clinical respiratory symptoms and the most common were general respiratory distress, cough, wheezing, sneezing, and nasal discharge. These results indicate that cat aelurostrongylosis is of clinical importance and, thus, needs to be included in differential diagnosis of feline respiratory diseases. The importance of the disease is discussed together with pros and cons of different conventional and innovative diagnostic approaches.

Diagnosis and risk factors of Aelurostrongylus abstrusus (Nematoda, Strongylida) infection in cats from Italy

Aelurostrongylus abstrusus (Nematoda, Strongylida) in cats and associated risk factors have been investigated by classical coprology in central (site A) and southern (site B) Italy, i.e. by floatations with sugar and zinc sulphate solutions and a Baermann technique. Overall, 227 individual stool samples (i.e. 162 from site A and 65 from site B) were processed and risk factors were related to infection by binary logistic multiple-regression models. The presence of A. abstrusus was used as the dependent variable and the epidemiological data as independent variables. Twenty-eight (17.3%) and 12 (18.5%) cats were positive for A. abstrusus in sites A and B, respectively, both using the Baermann and flotation with zinc sulphate solution methods. Six and three (from site A and B, respectively) of the infected cats were negative for A. abstrusus when faeces were processed with sugar solution. Stray and free-ranging ( P = 0.357), young cats ( P = 0.008) and the presence of respiratory symptoms ( P = 0.000) were risk factors for A. abstrusus infection. The results suggest that A. abstrusus is spread in Italy. Furthermore, these results possibly include infection in the differential diagnosis of feline respiratory diseases and offer a correct diagnostic approach by using either a Baermann method or flotation with zinc sulphate solution in suspected cases.