Cat Lung Research Articles

Detection of Feline Coronavirus in Bronchoalveolar Lavage Fluid from Cats with Atypical Lower Airway and Lung Disease: Suspicion of Virus-Associated Pneumonia or Pneumonitis.

The premortem understanding of the role of feline coronavirus (FeCoV) in the lungs of cats is limited as viruses are seldom inspected in the bronchoalveolar lavage (BAL) specimens of small animal patients. This study retrospectively analyzed the prevalence of FeCoV in BAL samples from cats with atypical lower airway and lung disease, as well as the clinical characteristics, diagnostic findings, and follow-up information. Of 1162 clinical samples submitted for FeCoV RT-nPCR, 25 were BAL fluid. After excluding 1 case with chronic aspiration, FeCoV was found in 3/24 (13%) BAL specimens, with 2 having immunofluorescence staining confirming the presence of FeCoV within the cytoplasm of alveolar macrophages. The cats with FeCoV in BAL fluid more often had pulmonary nodular lesions (66% vs. 19%, p = 0.14) and multinucleated cells on cytology (100% vs. 48%, p = 0.22) compared to the cats without, but these differences did not reach statistical significance due to the small sample size. Three cats showed an initial positive response to the corticosteroid treatment based on the clinical signs and radiological findings, but the long-term prognosis varied. The clinical suspicion of FeCoV-associated pneumonia or pneumonitis was raised since no other pathogens were found after extensive investigations. Further studies are warranted to investigate the interaction between FeCoV and lung responses in cats.

The study of the course of the infectious process in lungs of cats during experimental infection with SARS-CoV-2

Aim. To study and characterise the features of the course of coronavirus infection in a domestic cat model, as well as to assess the danger of SARSCoV-2 isolated in Russia for these animals based on the data obtained, with the possibility of extrapolating to wild felines.Material and Methods. For the study, model animals – Felis silvestris catus – were divided into 3 groups. The viral strain of SARS-Cov-2/human/RUS/Nsk-FRCFTM-1/2020 was cultivated on Vero E6 cell culture and then administered intranasally in a volume of 200 μl, 105TCID50/ml, to animals from the first and second groups. Model animals from the first group were euthanized and lung fragments were taken on 6–day post infection (d.p.i.), animals from the second group – on 14 d.p.i. The third group – the control group, was injected with saline in an equivalent volume. Histological sections colored with hematoxylin and eosin were investigated for pathomorphological changes in lung tissue using light microscopy.Results. According to the obtained results the pathomorphological picture in the lungs of experimental animals indicates the course of interstitial pneumonia for both 6 and 14 d.p.i. In addition, it has been determined that by 14 d.p.i. the growth of fibrous tissue in the lungs begins to be visualised, indicating the beginning of light regenerative processes.Conclusion. The study showed that cats are susceptible to the SARS-CoV-2 virus, and these model animals are characterized by the emergence of clinical manifestations and morphological patterns in the lungs, which correspond to interstitial pneumonia.

Ultrasound and x-ray examination at lung edema of domestic cat

The aim: This study aims to determine the diagnostic value of lung ultrasound compared with radiography for respiratory distress in cats.
 Materials and methods: The database of the veterinary center was analyzed. 130 animals diagnosed with pulmonary edema were selected. The lungs of sick cats were examined ultrasonographically; The line was counted in 4 anatomical sections on each hemithorax. A site was evaluated as positive when > 3 "B-lines" were detected. Animal treatment protocols were studied to clarify the final diagnosis (reference standard), and the sensitivity and specificity of lung ultrasound and chest X-ray for the diagnosis of pulmonary edema were calculated.
 Result: Cats with a final diagnosis of cardiogenic pulmonary edema had a greater number of positive areas on ultrasound than those, in which respiratory distress was caused by non-cardiogenic pulmonary edema. The overall sensitivity and specificity of US for the diagnosis of pulmonary edema were 87 % and 89 %, respectively, and these values were similar to those of chest radiography (85 % and 86 %, respectively). The use of ultrasound led to a false diagnosis of cardiogenic pulmonary edema (ie, a false-positive result) in animals with diffuse interstitial or alveolar changes.
 Conclusions: Ultrasound examination of the lungs in cats with respiratory distress syndrome is a promising diagnostic method. Emergency diagnosis of pulmonary edema in cats is difficult, especially in patients with severe shortness of breath, and limits the diagnostic evaluation. Chest x-rays are considered the standard diagnostic test, but the results are sometimes ambiguous and the process of obtaining the x-rays can increase respiratory distress in the animal.
 According to the results of the study, it was established, that ultrasound examination of the lungs can be used to differentiate the causes of shortness of breath (cardiogenic and non-cardiogenic) with sufficiently high sensitivity and specificity and less influence of the iatrogenic factor on the development of respiratory distress in cats, compared to chest radiography

Determination of Aelurostrongylus abstrusus Prevalence and Risk Factors in Cats from Balıkesir

The lungworms are nematodes that live as parasites in cat lungs. It is reported that the most common lungworm is Aelurostrongylus abstrusus in cats, and also Capillaria aerophila is observed. The lungworms can cause infection of the lower respiratory tract, often resulting in bronchitis and pneumonia. In this study, it was aimed to determine the prevalence and risk factors of A. abstrusus in cats in the Balıkesir province. This study was carried out on 100 cats in Balıkesir province. Fresh stool samples (>15 g) were collected for detection of lungworms after recorded all cat information (breed, age, sex, etc.). Parasite-specific L1 forms were determined from the stool samples by the Baerman-Wetzel technique. A. abstrusus L1's were found in 5 of the 100 stool samples examined. While symptoms of respiratory system disease were observed in 2 of the cats with lungworm, no clinical finding of the presence of parasites was found in 3 of them. A. abstrusus was observed at a level of 5% in this first prevalence study in cats in Balıkesir province.

Characterization of the pathogenicity of extraintestinal pathogenic Escherichia coli isolates from pneumonia-infected lung samples of dogs and cats in South Korea

This study aimed to investigate the pathogenicity of extraintestinal pathogenic Escherichia coli (ExPEC) isolated from dog and cat lung samples in South Korea. A total of 101 E. coli isolates were analyzed for virulence factors, phylogroups, and O-serogroups, and their correlation with bacterial pneumonia-induced mortality was elucidated. P fimbriae structural subunit (papA), hemolysin D (hlyD), and cytotoxic necrotizing factor 1 (cnf1) were highly prevalent in both species, indicating correlation with bacterial pneumonia. Phylogroups B1 and B2 were the most prevalent phylogroups (36.6% and 32.7%, respectively) and associated with high bacterial pneumonia-induced mortality rates. Isolates from both species belonging to phylogroup B2 showed high frequency of papA, hlyD, and cnf1. O-serogrouping revealed 21 and 15 serogroups in dogs and cats, respectively. In dogs, O88 was the most prevalent serogroup (n = 8), and the frequency of virulence factors was high for O4 and O6. In cats, O4 was the most prevalent serogroup (n = 6), and the frequency of virulence factors was high for O4 and O6. O4 and O6 serogroups were mainly grouped under phylogroup B2 and associated with high bacterial pneumonia-induced mortality. This study characterized the pathogenicity of ExPEC and described the probability of ExPEC pneumonia-induced mortality.

Ambient particulate matter (PM10)-induced injury in feline lung cells and nutritional intervention

Ambient particulate matter (APM) is extremely harmful to life's health. In this study, we investigated cellular injury in cat (Felix catus) lung cells (FCA-L2) exposed to organic and water-soluble extracts from APM. As well, the protective effect of vitamin E (VE), lycopene and a mixture of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) (molar concentration ratio of 2:1) against this damage was evaluated. Organic and water-soluble extracts induced oxidative stress in FCA-L2 cells, as evidenced by excess reactive oxygen species production and mitochondrial damage, while treatment with VE, lycopene and EPA: DHA remarkably alleviated these indices. It was further found that treatment with EPA: DHA decreased lactate dehydrogenase and malondialdehyde, as well as increased activities of superoxide dismutase, glutathione peroxidase and catalase. Our study confirmed that nutrients mediates APM-induced oxidative stress via antioxidant proteins. Also, these findings could provide new insights into reducing APM-induced cytotoxicity by nutritional supplementation based on antioxidant compounds for animals.

The Upper Respiratory Tract of Felids Is Highly Susceptible to SARS-CoV-2 Infection.

Natural or experimental infection of domestic cats and virus transmission from humans to captive predatory cats suggest that felids are highly susceptible to SARS-CoV-2 infection. However, it is unclear which cells and compartments of the respiratory tract are infected. To address this question, primary cell cultures derived from the nose, trachea, and lungs of cat and lion were inoculated with SARS-CoV-2. Strong viral replication was observed for nasal mucosa explants and tracheal air–liquid interface cultures, whereas replication in lung slices was less efficient. Infection was mainly restricted to epithelial cells and did not cause major pathological changes. Detection of high ACE2 levels in the nose and trachea but not lung further suggests that susceptibility of feline tissues to SARS-CoV-2 correlates with ACE2 expression. Collectively, this study demonstrates that SARS-CoV-2 can efficiently replicate in the feline upper respiratory tract ex vivo and thus highlights the risk of SARS-CoV-2 spillover from humans to felids.

Differential susceptibility of SARS-CoV-2 in animals: Evidence of ACE2 host receptor distribution in companion animals, livestock and wildlife by immunohistochemical characterisation.

Angiotensin converting enzyme 2 (ACE2) is a host cell membrane protein (receptor) that mediates the binding of coronavirus, most notably SARS coronaviruses in the respiratory and gastrointestinal tracts. Although SARS‐CoV‐2 infection is mainly confined to humans, there have been numerous incidents of spillback (reverse zoonoses) to domestic and captive animals. An absence of information on the spatial distribution of ACE2 in animal tissues limits our understanding of host species susceptibility. Here, we describe the distribution of ACE2 using immunohistochemistry (IHC) on histological sections derived from carnivores, ungulates, primates and chiroptera. Comparison of mink (Neovison vison) and ferret (Mustela putorius furo) respiratory tracts showed substantial differences, demonstrating that ACE2 is present in the lower respiratory tract of mink but not ferrets. The presence of ACE2 in the respiratory tract in some species was much more restricted as indicated by limited immunolabelling in the nasal turbinate, trachea and lungs of cats (Felis catus) and only the nasal turbinate in the golden Syrian hamster (Mesocricetus auratus). In the lungs of other species, ACE2 could be detected on the bronchiolar epithelium of the sheep (Ovis aries), cattle (Bos taurus), European badger (Meles meles), cheetah (Acinonyx jubatus), tiger and lion (Panthera spp.). In addition, ACE2 was present in the nasal mucosa epithelium of the serotine bat (Eptesicus serotinus) but not in pig (Sus scrofa domestica), cattle or sheep. In the intestine, ACE2 immunolabelling was seen on the microvillus of enterocytes (surface of intestine) across various taxa. These results provide anatomical evidence of ACE2 expression in a number of species which will enable further understanding of host susceptibility and tissue tropism of ACE2 receptor‐mediated viral infection.

Immunology of COVID-19 and its clinical implications for therapy

The newly emerged novel coronavirus (COVID-19) is highly contagious, large enveloped, single-stranded, nonsegmented, positive-sense RNA viruse that belong to coronaviridae family and genus Beta coronavirus The viruses of coronaviridae family are further divided into two subfamilies;Middle East respiratory syndrome coronavirus and severe acute respiratory syndrome coronavirus COVID-19 show close similarities to SARS-CoV due to phylogenetic relationship and genome structure Word Health Organisation has designated the current pandemic of SARS-CoV-2 infection as COVID-19 The virus shows high infectivity and mainly transmitted in the form of droplets with an incubation period of about 4-5 days The onset of symptoms in patients is usually within 11-12 days Here, Rao and Gupta discuss the immunology of COVID-19

Pathogistological changes in the lungs of Felis silvestris catus when infected with Aelurostrongylus abstrusus

Aelurostrongylus abstrusus is a parasite that belongs to Nematoda type, Metastrongyloidea superfamily, Angiostrongylidae family, Aelurostrongylus genus and is known as feline helminth, whose intermediate hosts are slugs and snails and reservoir hosts are mice and birds. In cats, Aelurostrongylus abstrusus parasitizes in bronchioles and alveoli, causing specific inflammatory changes in the lower respiratory tract and enables the development of such clinical signs as cough, shortness of breath as well as mucous-purulent discharge from the nasal cavity, when complicated by bacterial infections. Females of parasite lay eggs, which the larvae of L1 hatch from. Subsequently, these larvae cough with bronchial mucus and are swallowed by an animal. They pass through the digestive channel without changes and together with the faeces are released into the environment. The first stage larvae actively penetrate into the body of the slugs, fade twice and are becoming invasive. Duration of larvae development from the stage L1 to L3 depends on the biological cycle of intermediate hosts – slugs and snails. Cats are becoming infected by eating slugs or snails with invasive larvae of the third stage (L3), which are transmitted from the digestive channel of the definitive host (cat) with blood flow to the lungs. Usually, the pathogen has low pathogenicity and invasions are primarily detected after animal’s death, during pathoanatomical dissection. Acute clinical signs of the disease have not been described much up to date. The article presents the results of pathomorphological examination of the cat's lungs infected by Aelurostrongylus abstrusus. The severity of pathomorphological changes of the cat’s pulmonary tissue depends on the intensity of the invasion. When dissected, the lungs appear unevenly coloured, dark red with light and slightly denser areas, where focal parasitic nodules are clearly distinct, surrounded by pink halo and different in size but mostly round, dense consistency. Main morphological characteristic of Aelurostrongylus abstrusus infection is the presence of numerous eggs and L1 larvae in the alveoli but also in the bronchi. Helminth eggs accumulated in the alveolar lumps, surrounded by a thin shell; a severe cellular reaction from lymphocytes, macrophages and histiocytes occurred around this shell. An inflammatory reaction resulted in the thickening of the interstitial tissue with a strong vascular response, characterized by fraying and edema of the vessel walls. The results of pathomorphological researches have shown that the main changes were localized in the lungs and bronchial tubes with diffuse damage of the pulmonary tissue parenchyma and development of croupous pneumonia.

Production of Neutrophil Extracellular Traps Contributes to the Pathogenesis of Francisella tularemia.

Francisella tularensis(Ft) is a highly virulent, intracellular Gram-negative bacterial pathogen. Acute Ft infection by aerosol route causes pneumonic tularemia, characterized by nodular hemorrhagic lesions, neutrophil-predominant influx, necrotic debris, fibrin deposition, and severe alveolitis. Ft suppresses activity of neutrophils by impairing their respiratory burst and phagocytic activity. However, the fate of the massive numbers of neutrophils recruited to the infection site is unclear. Here, we show that Ft infection resulted in prominent induction of neutrophil extracellular traps (NETs) within damaged lungs of mice infected with the live attenuated vaccine strain of Ft(Ft-LVS), as well as in the lungs of domestic cats and rabbits naturally infected with Ft. Further, Ft-LVS infection increased lung myeloperoxidase (MPO) activity, which mediates histone protein degradation during NETosis and anchors chromatin scaffolds in NETs. In addition, Ft infection also induced expression of peptidylarginine deiminase 4, an enzyme that causes citrullination of histones during formation of NETs. The released NETs were found largely attached to the alveolar epithelium, and disrupted the thin alveolar epithelial barrier. Furthermore, Ft infection induced a concentration-dependent release of NETs from neutrophils in vitro. Pharmacological blocking of MPO reduced Ft-induced NETs release, whereas addition of H2O2 (a substrate of MPO) significantly augmented NETs release, thus indicating a critical role of MPO in Ft-induced NETs. Although immunofluorescence and electron microscopy revealed that NETs could efficiently trap Ft bacteria, NETs failed to exert bactericidal effects. Taken together, these findings suggest that NETs exacerbate tissue damage in pulmonary Ft infection, and that targeting NETosis may offer novel therapeutic interventions in alleviating Ft-induced tissue damage.

Molecular detection of Pneumocystis in the lungs of cats.

The genus Pneumocystis comprises potential pathogens that reside normally in the lungs of a wide range of mammals. Although they generally behave as transient or permanent commensals, they can occasionally cause life-threatening pneumonia (Pneumocystis pneumonia; PCP) in immunosuppressed individuals. Several decades ago, the presence of Pneumocystis morphotypes (trophic forms and cysts) was described in the lungs of normal cats and cats with experimentally induced symptomatic PCP (after immunosuppression by corticosteroids); yet to date spontaneous or drug-induced PCP has not been described in the clinical feline literature, despite immunosuppression of cats by long-standing retrovirus infections or after kidney transplantation. In this study, we describe the presence of Pneumocystis DNA in the lungs of normal cats (that died of various unrelated causes; n = 84) using polymerase chain reactions (PCRs) targeting the mitochondrial small and large subunit ribosomal RNA gene (mtSSU rRNA and mtLSU rRNA). The presence of Pneumocystis DNA was confirmed by sequencing in 24/84 (29%) cats, with evidence of two different sequence types (or lineages). Phylogenetically, lineage1 (L1; 19 cats) and lineage 2 (L2; 5 cats) formed separate clades, clustering with Pneumocystis from domestic pigs (L1) and carnivores (L2), respectively. Results of the present study support the notion that cats can be colonized or subclinically infected by Pneumocystis, without histological evidence of damage to the pulmonary parenchyma referable to pneumocystosis. Pneumocystis seems most likely an innocuous pathogen of cats’ lungs, but its possible role in the exacerbation of chronic pulmonary disorders or viral/bacterial coinfections should be considered further in a clinical setting.

Molecular characterization of a feline calicivirus isolated from tiger and its pathogenesis in cats

Feline calicivirus (FCV) is a virus that causes respiratory disease in cats. In this study, the FCV TIG-1 was isolated from Siberian tiger feces collected in 2014 in Heilongjiang Province, China. Phylogenetic analysis among TIG-1 and other FCVs showed that TIG-1 does not share the same lineage with other FCV isolates from Heilongjiang or other regions in China but is located in the same cluster with the FCV strain Urbana, which was isolated from the United States. The growth kinetics in vitro and the pathogenicity in cats between TIG-1 and the domestic cat-origin FCV strain F9 (vaccine strain) and strain 2280 were compared. We found that the growth kinetics of strains TIG-1 and 2280 were faster than that of strain F9 from 12h to 36h post-infection, indicating that strains TIG-1 and 2280 produce infectious virions and reach peak yields earlier. Challenge experiments in cats showed that TIG-1 grew faster than the other two strains in the lungs of cats and that TIG-1 is a virulent FCV with 100% morbidity and lethality. In addition, the histopathological results showed that the virulent TIG-1 strain directly led to severe lung tissue damage and indirectly led to intestinal damage. The results presented here show that a tiger-origin FCV exhibits high virulence in cats.

Effects of High-Intensity Swimming on Lung Inflammation and Oxidative Stress in a Murine Model of DEP-Induced Injury.

Studies have reported that exposure to diesel exhaust particles (DEPs) induces lung inflammation and increases oxidative stress, and both effects are susceptible to changes via regular aerobic exercise in rehabilitation programs. However, the effects of exercise on lungs exposed to DEP after the cessation of exercise are not clear. Therefore, the aim of this study was to evaluate the effects of high-intensity swimming on lung inflammation and oxidative stress in mice exposed to DEP concomitantly and after exercise cessation. Male Swiss mice were divided into 4 groups: Control (n = 12), Swimming (30 min/day) (n = 8), DEP (3 mg/mL—10 μL/mouse) (n = 9) and DEP+Swimming (n = 8). The high-intensity swimming was characterized by an increase in blood lactate levels greater than 1 mmoL/L between 10th and 30th minutes of exercise. Twenty-four hours after the final exposure to DEP, the anesthetized mice were euthanized, and we counted the number of total and differential inflammatory cells in the bronchoalveolar fluid (BALF), measured the lung homogenate levels of IL-1β, TNF-α, IL-6, INF-ϫ, IL-10, and IL-1ra using ELISA, and measured the levels of glutathione, non-protein thiols (GSH-t and NPSH) and the antioxidant enzymes catalase and glutathione peroxidase (GPx) in the lung. Swimming sessions decreased the number of total cells (p<0.001), neutrophils and lymphocytes (p<0.001; p<0.05) in the BALF, as well as lung levels of IL-1β (p = 0.002), TNF-α (p = 0.003), IL-6 (p = 0.0001) and IFN-ϫ (p = 0.0001). However, the levels of IL-10 (p = 0.01) and IL-1ra (p = 0.0002) increased in the swimming groups compared with the control groups, as did the CAT lung levels (p = 0.0001). Simultaneously, swimming resulted in an increase in the GSH-t and NPSH lung levels in the DEP group (p = 0.0001 and p<0.002). We concluded that in this experimental model, the high-intensity swimming sessions decreased the lung inflammation and oxidative stress status during DEP-induced lung inflammation in mice.

Greater virulence of highly pathogenic H5N1 influenza virus in cats than in dogs.

Highly pathogenic H5N1 influenza virus continues to infect animals and humans. We compared the infectivity and pathogenesis of H5N1 virus in domestic cats and dogs to find out which animal is more susceptible to H5N1 influenza virus. When cats and dogs were infected with the H5N1 virus, cats suffered from severe outcomes including death, whereas dogs did not show any mortality. Viruses were shed in the nose and rectum of cats and in the nose of dogs. Viruses were detected in brain, lung, kidney, intestine, liver, and serum in the infected cats, but only in the lung in the infected dogs. Genes encoding inflammatory cytokines and chemokines, Toll-like receptors, and apoptotic factors were more highly expressed in the lungs of cats than in those of dogs. Our results suggest that the intensive monitoring of dogs is necessary to prevent human infection by H5N1 influenza virus, since infected dogs may not show clear clinical signs, in contrast to infected cats.

Local pulmonary immune responses in domestic cats naturally infected with Cytauxzoon felis

Cytauxzoonosis is a hemoprotozoal disease of cats and wild felids in the South and Southeastern United States caused by Cytauxzoon felis. Although the causative agent has been recognized since the seventies, no study has examined the local immune response in affected organs, such as the lung, and compared them to the lungs of uninfected domestic cats. Previous studies have suggested that the histopathologic findings in the lungs of C. felis-infected cats are caused by the release of pro-inflammatory mediators, such as cytokines and increased production of inducible nitric oxide synthase (iNOS), by the infected macrophages. Our laboratory had previously found an upregulation of the adhesion molecule CD18, which can stimulate the release of these pro-inflammatory mediators. The objective of this study was to characterize local pulmonary immune responses in cats naturally infected with C. felis. Immunohistochemistry was performed to detect tumor necrosis factor-α (TNF-α), interleukin (IL)-1β, IL-6, iNOS, and major histocompatibility complex (MHC) II in 19 lungs from affected cats that died between 2005 and 2013. Results showed increased expression of all of these molecules when compared to lungs from uninfected, healthy cats. Furthermore, MHC II is expressed in the endothelium of C. felis naturally infected cats. These results support that there is a marked, local, pro-inflammatory immune response that can contribute to the pathogenesis of cytauxzoonosis in the lungs.

Aelurostrongylus abstrusus in a stray cat’s blood stream

Aelurostrongylus abstrusus (Raillet), the cat lungworm, is a parasitic round worm which lives in the terminal bronchioles and the alveolar ducts inside the lungs of cats as final hosts. Snails or slugs can be intermediate hosts while rodents, frogs, toads, lizards, birds, and snakes can play the role of transporter from the intermediate host into the final host. The ingested third-stage larvae migrate towards the lungs through the blood vessels. In this research, first, the observation of A. abstrusus infection in a stray cat in Iran is described. Later, the larval detection of this worm in infected cat’s blood throughout the world will be discussed.

Pulmonary hypertension and the right ventricle in hypoxia

Hypoxia causes pulmonary vasoconstriction. Regional hypoxic vasoconstriction improves the matching of perfusion to alveolar ventilation. Global hypoxic vasoconstriction increases right ventricular afterload. The hypoxic pulmonary pressor response is universal in mammals and in birds, but with considerable interspecies and interindividual variability. Chronic hypoxia induces pulmonary hypertension in proportion to initial vasoconstriction. Prolonged hypoxic exposure is also associated with an increase in red blood cell mass, which aggravates pulmonary hypertension by an increase in blood viscosity. Hypoxic pulmonary hypertension in humans is usually mild to moderate, but pulmonary vascular pressure-flow relationships are steep, which corresponds to a substantial afterload on the right ventricle during exercise. A partial recovery of 10-25% of the hypoxia-induced decrease in maximal oxygen uptake has been reported with intake-specific pulmonary vasodilating interventions. Hypoxia has been reported to decrease myocardial fibre contractility in vitro. However, the acutely hypoxic right ventricle remains able to preserve the coupling of its contractility to increased afterload in intact animals. Echocardiographic studies of the right ventricle in healthy hypoxic human subjects show altered diastolic function, but systolic function that is preserved or even increased acutely and slightly depressed chronically. These findings are more pronounced in patients with chronic mountain sickness. Their clinical significance remains incompletely understood. Almost no imaging studies of right ventricular function have been reported in a minority of subjects who develop severe pulmonary hypertension and clinical right ventricular failure in hypoxia. No imaging studies of right ventricular function during hypoxic exercise in normal subjects are yet available. Thus, while it is plausible that the right ventricle limits exercise capacity in hypoxia, this still needs to be firmly established.

Light Microscopy of Bronchial Associated Lymphoid Tissue of Healthy Domestic Cat with Suggested New Nomenclature

Background: Bronchial associated lymphoid tissue (BALT) is present in humans and several other animal species including the cat which was reported that only present during infection. The role of BALT in antigen uptake and immune response is well established, and its location is varied in different species. The aim of this study was to investigate the presence and morphology of healthy cat lungs lymphoid tissue using traditional light microscopical techniques. Methods: Tissues were collected from all lung lobes from (2 to 3 years old) healthy domestic cats and processed using standard histological techniques. The tissues were cuts into small pieces and embedded in an Epon-Araldite mixture. Tissue sections were stained with hematoxylin and eosin, and periodic acid Schiff stains. Results: The majority of lymphatic tissue was located along the bronchial tree and associated neurovascular bundles. Both nodular and diffuse forms were present in healthy domestic cats. These lymphoid tissues extended distally into the wall of terminal bronchioles. The nodules had distinct marginal and central areas and were located in the tunica adventitia of the bronchi, bronchioles and diffusely infiltrated the adventitia of the wall of adjacent blood vessels. However, a diffuse form was found primarily in the submucosa of the bronchial tree intermingled with the submucosal glands. In addition, the diffuse form was also located around bronchioles, blood vessel and alveoli. Conclusion: This study shows presence of diffuse and nodular forms of lymphoid tissues within the lungs of a healthy cat. The nodular form was not only associated with bronchial tree all the way down to terminal bronchioles, but also with veins, arteries and parenchyma of the lungs. Hence, PALT (Pulmonary Associated Lymphatic Tissue) seems to be a better nomenclature than BALT to describe the relationship and distribution of the distal lymphatic tissue in the lungs of healthy domestic cat.

Structural and ultrastructural changes in the lungs of cats Felis catus (Linnaeus, 1758) experimentally infected with D. immitis (Leidy, 1856)

Clinical signs are seldom observed in feline heartworm disease, and the pathophysiological changes in the lungs of infected animals remain undefined. The goal of this study was to evaluate the structural and ultrastructural changes in the lungs of cats experimentally infected with Dirofilaria immitis. Six healthy cats were each infected with two adult heartworms by intravenous transplantation (Receptor Group, RG). The control group consisted of two uninfected animals kept under the same conditions as the RG. At 42 days after transplantation, all cats were euthanized and necropsied for worm recovery and collection of lung samples for examination by light microscopy (LM) and transmission electron microscopy. By LM, lung sections from the six infected cats exhibited bronchial and bronchiolar lesions. Alterations in all tissues of the pulmonary arteries were observed in the infected animals. In conclusion, cats infected experimentally with D. immitis developed lesions in their lungs as a consequence of arterial disease and intense interstitial pneumonia.