Reversible pulmonary hypertension associated with lungworm infection in a young cat

Developmental lung disease in a cat associated with high probability of severe pulmonary hypertension: natural history, histopathology and genetic analysis

Case summary

This report describes the diagnostic findings, natural history and genetic analysis of the candidate gene Forkhead Box F1 (FOXF1) in a young cat with developmental lung disease and high probability of pulmonary hypertension. A 1-year-old male entire Chartreux cat was referred for cardiac murmur investigation and exercise intolerance. Echocardiography identified a high-velocity tricuspid regurgitant jet with right-sided cardiac changes, supporting a high probability of pulmonary hypertension. No congenital cardiac shunts or left-sided cardiac changes were found to support a primary cardiac cause of pulmonary hypertension. Extensive laboratory work, thoracic radiographs and CT were performed. Histopathological characterisation (lung biopsy and later post mortem) was necessary to reach the final diagnosis. Eight months after diagnosis, the cat developed right-sided congestive heart failure, eventually leading to euthanasia. Survival from diagnosis to death was 12 months.

Relevance and novel information

Developmental lung disease belongs to a group of diffuse lung diseases in humans associated with pulmonary hypertension. The veterinary literature describing lung growth disorders in cats is sparse, and the present report provides information on clinical presentation and progression alongside a thorough diagnostic workup, which may aid clinicians in identifying this condition. Lung biopsy was pivotal in reaching the final diagnosis. No causal variants in FOXF1 were identified.

Clinical, Radiological, and Echocardiographic Findings in Cats Infected by Aelurostrongylus abstrusus

Cats infected by Aelurostrongylus abstrusus may show a plethora of clinical signs, and pulmonary hypertension (PH) seems to be one of the possible alterations induced by the infection; however, data on this association are scant and contradictory. Therefore, the aims of this study were to investigate the association between aelurostrongylosis and PH and to evaluate the correlation between the number of A. abstrusus larvae expelled in the faeces and the clinical, echocardiographic, and radiological alterations. Fifteen cats (i.e., eight males and seven females) older than 3 months and naturally infected by A. abstrusus with different parasitic loads, expressed as larvae per grams of faeces (l.p.g.), were enrolled in the study. Each animal underwent clinical, echocardiographic, and radiographic examinations. Most cats (i.e., 10/15) showed pathological patterns on thoracic radiograms; particularly, the alveolar pattern (four cats), interstitial-nodular pattern (five cats), and bronchial pattern (one cat). No significant echocardiographic findings of PH were detected. No correlation between the number of l.p.g. and the severity of clinical signs was observed, but a significant correlation with activated partial thromboplastin time (aPTT), radiographic alterations (interstitial nodular pattern), and ultrasonographic findings (RIVIDs) were noticed. These findings suggest that other factors such as animal age and health status, as well as comorbidity, may influence the presentation of the disease or the clinical manifestation and severity of the disease.

Feline pulmonary hypertension: are we overlooking an important comorbidity?

Pulmonary hypertension (PH) is a potential complication in many disease states, yet it has been largely overlooked in feline medicine. Recently, increased awareness of potential underlying causes has led to a wider understanding of the disease process in humans, with a focus on tailoring therapy to include specific treatment of the underlying etiology. Most of these treatments are not yet available in veterinary medicine, but as they move from the human to the veterinary field, it would be beneficial to better understand the forms of PH encountered in different species. Recently, diagnosis and classification of PH in dogs has been the focus of an American College of Veterinary Internal Medicine consensus statement, yet this condition has received little attention in cats. It is therefore our intention to raise awareness of this condition in cats and to propose a classification system for the types of PH seen in feline patients. As new medications are developed for the treatment of PH, it is important to recognize which forms of PH are seen in feline patients and understand the etiology of the disease. There are many reports of PH (or suspected PH based on echocardiographic assessment) in cats. In this review, we highlight the large number of conditions, and different etiologies, that are associated with PH. Improving understanding of this condition will bring us closer to being able to investigate the benefits of potential new diagnostics and therapies as they become available.

Ultrasonography of Parasitic Diseases in Domestic Animals: A Systematic Review

Simple Summary

The aim of this literature review was to summarize the current knowledge on the application of ultrasonography in diagnosis, staging and monitoring of helminthic diseases in domestic animals. We selected and analyzed 122 papers about the application of ultrasonography in parasitic disease in ruminants, equids, swine, and companion animals. Helminths can be recognized in ultrasound images by their morphology, size, and location. In some cases, the parasites are not directly seen by ultrasound, but the lesions caused by them can be easily visualized. Ultrasound imaging is taking on an increasingly important role in veterinary parasitology.

Abstract

The aim of this review was to summarize the current knowledge on the application of ultrasonography in diagnosis, staging and monitoring of helminthic diseases in domestic animals. Only peer reviewed papers written in English language were included in this systematic review. All papers concerning unicellular parasites, wild animals, non-domestic experimental animals, or ex vivo or in vitro applications of ultrasonography were excluded from the review. A total of 122 papers met the inclusion criteria. Among them 47% concerned nematodes, 37% cestodes, and 16% trematodes with the genus Dirofilaria, Echinococcus, and Fasciola the most represented, respectively. Helminths can be recognized in ultrasound images by their morphology, size, and location. In some cases, the parasite stages are not directly seen by ultrasound, but the lesions caused by them can be easily visualized. Ultrasound imaging is taking on an increasingly important role in the diagnosis, staging, monitoring, and control of parasitic diseases in veterinary medicine. However, it cannot replace the clinical approach and the diagnostic tests commonly used in veterinary parasitology.

First Case of Clinical Cat Aelurostrongylosis in the Brazilian Amazon: Clinical and Molecular Insights

Aelurostrongylus abstrusus is the most important respiratory parasite infecting domestic cats worldwide. Nevertheless, most records and epizootiological data come from Europe, whilst poor and fragmentary information are available for other regions, including the Americas. The present article describes the first description of cat aelurostrongylosis from Amazonia, Brazil. Eighty-one cats, 13 from a shelter and 68 admitted at the Teaching and Research Unit in Veterinary Medicine (UV) at the Federal University of Acre (UFAC), Brazil, were included in the study. For all cats, three faecal samples from consecutive defecations were examined using the Baermann’s technique. Nematode first stage larvae (L1), retrieved in 2/81 (2.5%) samples, were microscopically identified as A. abstrusus and then subjected to a molecular assay able to identify the three most important species of metastrongyloids infecting felids. This test confirmed the A. abstrusus identity in one sample, while the second scored negative. The cat with confirmed aelurostrongylosis showed radiographic changes, i.e., an interstitial pattern, compatible with the infection. The other cat, which scored positive at the Baermann’s examination, was apparently healthy at the physical examination and showed no thoracic alterations. The occurrence of A. abstrusus in domestic cats from Brazilian Amazon is herein demonstrated for the first time. Clinical, epizootiological and molecular implications are discussed.

Cat Respiratory Nematodes: Current Knowledge, Novel Data and Warranted Studies on Clinical Features, Treatment and Control

The nematodes Aelurostrongylus abstrusus, Troglostrongylus brevior and Capillaria aerophila are the most important parasites inhabiting the airways of cats. They are receiving growing attention from academia, pharmaceutical companies and veterinarians, and are now considered a primary cause of respiratory diseases in feline clinical practice and parasitology. In the past few years, several studies have been conducted in both natural and experimental settings to increase knowledge, provide new insights and fill gaps on respiratory parasitoses of cats. Awareness and knowledge of clinical scenarios towards appropriate and timely diagnosis and prompt and efficacious treatment options have become a priority to investigate. At the same time, chemopreventative approaches have been evaluated to assess the geographical spreading of these parasites and the rise in the number of clinical cases in cat populations of different countries. Given the intense accumulation of novel data, this review presents and discusses the state of the art and the latest updates on the clinical features, treatment, and control of major respiratory parasitoses of cats. Moreover, food for thought is also provided with the aim of spurring on new studies in the near future.

Aelurostrongylus abstrusus Infections in Domestic Cats (Felis silvestris catus) from Antioquia, Colombia

Although Aelurostrongylus abstrusus infections in domestic cats (Felis silvestris catus) have sporadically been reported in Colombia, there is still no data available on epidemiology nor on the biology of this neglected lungworm parasite. Thus, this epidemiological study aimed to evaluate the occurrence of patent A. abstrusus infections in domestic cats from the Colombian Federal State of Antioquia. In total, 473 fecal samples of indoor/outdoor domestic cats were collected and analyzed thereafter by the Baermann funnel migration technique for the presence of A. abstrusus first stage larvae 1 (L1). The occurrence of A. abstrusus was confirmed in 0.4% (2/473) of investigated cats. Due to the presence of patent A. abstrusus infections in investigated cats, it is unfailing to include this lungworm within differential diagnoses of feline pulmonary disorders. Despite the fact that the Baermann funnel technique is currently the cheapest and the gold standard diagnostic tool for feline aelurostrongylosis, this technique is still unknown by Colombian veterinary surgeons and rarely utilized in small animal veterinary clinics. The current survey intends to generate awareness on this neglected parasitosis and to be considered as a baseline study for future surveys monitoring feline aelurostrongylosis not only in domestic/stray cats but also in endemic wild felid species of Colombia.

Fatal Pulmonary Hypertension and Right-Sided Congestive Heart Failure in a Kitten Infected with Aelurostrongylus abstrusus

Simple Summary

Infections caused by lungworms are an emerging issue in feline medicine. Clinical features in cats may vary from subclinical infections to a severe disease, occasionally including fatal pneumonia, depending on different factors, e.g., lungworm species, parasitic burden, and age of the animal. A case of infection caused by Aelurostrongylus abstrusus in a domestic kitten presenting acute dyspnoea and ascites is presented here. Clinical, radiological, echocardiographic, parasitological, molecular, and pathological data are described. This is the first report of life-threatening pulmonary hypertension inducing congestive heart failure caused by A. abstrusus infection in a domestic kitten.

Abstract

Aelurostrongylus abstrusus is considered the most important respiratory nematode of domestic cats worldwide. This parasite inhabits the alveoli, alveolar ducts, and bronchioles and causes a subacute to chronic respiratory clinical disease. Clinical signs may occur in domestic cats of any age, though they are more often described in young animals. Physical examination, echocardiography, thoracic radiography, pulmonary and cardiac pathological findings, classical, and molecular parasitological analysis of a six-month-old kitten referred at the Veterinary Teaching Hospital of the University of Pisa (Italy) led to a diagnosis of parasitic bronchopneumonia caused by A. abstrusus, which was complicated by severe pulmonary hypertension (PH) and right-sided congestive heart failure (R-CHF) that caused the death of the animal. Cases of reversible PH associated with A. abstrusus infection have been seldom reported in cats. This is the first report of fatal PH and R-CHF in a kitten with clinical aelurostrongylosis.

Clinical-parasitological Screening for Respiratory Capillariosis in Cats in Urban Environments

Respiratory capillariosis is a widely distributed zoonotic parasitic disease caused by the nematode Capillaria aerophila (Trichocephalida, Trichuridae) that commonly infects wild carnivores but also cats and dogs. This retrospective study aims to describe cases of respiratory capillariosis in cats from the city of Belgrade, Serbia. Between 2015 and 2019, a total of 155 pet cats with or without respiratory symptoms were submitted to physical examination and parasitological examination of the feces. All cats lived indoor but had free access to outdoor. In suburban settlements, wild carnivores commonly share their living environments with owned cats and dogs. It can be assumed that more intense urbanization spreading into the natural habitats of will carnivores creates the opportunity for closer and more frequent contacts between the population of cats and feral carnivores which might increase the risk of feline contamination. The findings confirm the existence of capillaries in cats in urban areas of the city of Belgrade, contribute to a better understanding of the epidemiology of this nematode and warn that, because of close contacts between cats of pets and humans, capillaries can cause human infection.

Efficacy of imidacloprid 10%/moxidectin 1% spot-on formulation (Advocate®) in the prevention and treatment of feline aelurostrongylosis

Background

In three randomized, controlled laboratory efficacy studies, the efficacy in the prevention of patent infections of a topical combination of imidacloprid 10%/moxidectin 1% (Advocate® spot-on formulation for cats, Bayer Animal Health GmbH) against larval stages and immature adults of Aelurostrongylus abstrusus, as well as the treatment efficacy of a single or three monthly treatments against adult A. abstrusus, were evaluated.

Methods

Cats were experimentally inoculated with 300–800 third-stage larvae (L3). Each group comprised 8 animals and the treatment dose was 10 mg/kg bodyweight (bw) imidacloprid and 1 mg/kg bw moxidectin in each study. Prevention of the establishment of patent infections was evaluated by two treatments at a monthly interval at three different time points before and after challenge infection. Curative efficacy was tested by one or three treatments after the onset of patency. Worm counts at necropsy were used for efficacy calculations.

Results

In Study 1, the control group had a geometric mean (GM) of 28.8 adult nematodes and the single treatment group had a GM of 3.4 (efficacy 88.3%). In Study 2, the control group had a GM of 14.3, the prevention group had a GM of 0 (efficacy 100%), while the treatment group had a GM of 0.1 (efficacy 99.4%). In Study 3, the GM worm burden in the control group was 32.6 compared to 0 in all three prevention groups (efficacy 100% for all of those groups).

Conclusions

The monthly administration of Advocate® reliably eliminated early larval stages and thereby prevented lung damage from and patent infections with A. abstrusus in cats. Regarding treatment, a single application of Advocate® reduced the worm burden, but it did not sufficiently clear the infection. In contrast, three monthly treatments were safe and highly efficacious against A. abstrusus.

Doppler-derived echocardiographic evidence of pulmonary hypertension in cats with left-sided congestive heart failure

INTRODUCTION

Pulmonary hypertension (PH) caused by left-sided congestive heart failure (L-CHF) is common in dogs and contributes to clinical signs and outcome. The aim of this study was to evaluate the prevalence of Doppler echocardiography-derived PH in a population of cats with L-CHF.

ANIMALS

The study involved 131 cats with L-CHF and 56 control cats.

METHODS

The study design is retrospective, observational study. Tricuspid regurgitation velocity, right atrial dimension, right ventricular (RV) dimension and function, RV wall thickness, pulmonary artery (PA) dimension, Doppler-derived systolic time intervals of PA flow, and presence of septal flattening were evaluated. Pulmonary hypertension was considered if tricuspid regurgitation velocity was >2.7 m/s.

RESULTS

Tricuspid regurgitation was present in 57/131 (44%) of cats with L-CHF and 24/56 (43%) in control cats based on color flow Doppler. Doppler-derived of PH was identified in 22/131 cats with L-CHF (17%). In 15/22 cats, PH was associated with cardiomyopathy, in 5/22 cases with congenital heart disease, and in 2/22 cases with other causes. Cats with Doppler-derived PH more often had chronic L-CHF, as opposed to acute L-CHF (p<0.05). All cats with Doppler-derived PH had subjectively-assessed right-sided heart enlargement, with larger right atrial and RV diameters (p<0.001), increased RV wall thickness (p<0.05), and higher prevalence of septal flattening (<0.001) and PA enlargement (p<0.05).

CONCLUSIONS

Pulmonary hypertension identified by Doppler echocardiography is not a common finding in cats with L-CHF. Right-sided heart enlargement, more frequently observed, may raise the suspicion of PH in cats with L-CHF.

Diagnosis of Aelurostrongylus abstrusus verminous pneumonia via sonography-guided fine-needle pulmonary parenchymal aspiration in a cat

Case summary A 9-year-old, male neutered, indoor–outdoor domestic shorthair cat from the northern Alabama countryside presented for a 3 week history of coughing, lethargy and an episode of self-resolving dyspnea that occurred 1 week prior to presentation. Three-view thoracic radiographs revealed a moderate-to-severe, diffuse, mixed bronchial to structured interstitial (miliary-to-nodular) pulmonary pattern in all lung lobes with peribronchial cuffing and multifocal areas of mild patchy alveolar opacity. Ultrasound-guided evaluation and fine-needle aspiration of the caudodorsal lung parenchyma was performed with sedation. Cytology revealed many widely scattered Aelurostrongylus abstrusus larvae and ova. Upon the confirmed diagnosis of A abstrusus verminous pneumonia, treatment with fenbendazole and selamectin resulted in complete resolution of clinical signs within 6 weeks of the initial diagnosis.

Relevance and novel information We report herein the first documented case in the Americas of A abstrusus verminous pneumonia diagnosed via cytologic evaluation of an in vivo, percutaneous ultrasound-guided fine-needle aspirate of affected lung. Additionally, to our knowledge, we offer the first account of the sonographic (pulmonary) features of the disease.

Case report: Severe and progressive bronchopneumonia by Aelurostrongylus abstrusus in an adopted stray cat from Portugal

The cat lungworm Aelurostrongylus abstrusus is the most common respiratory parasite of cats. This nematode has a worldwide distribution and is considered an emerging pathogen. Respiratory signs overlap with those of other pathologies, and some agents which co-exist in the same animal may concur in the clinical scenario. Nonetheless, feline verminous bronchopneumonia is underestimated by practitioners and is not commonly included in differential diagnosis in routine practice. The present report describes the clinical presentation of a 6-month old stray cat from central Portugal, which developed respiratory distress. A clinical improvement of lower respiratory signs was achieved after a course of doxycycline and prednisolone course. However, a relapse with a progressive decline in the respiratory functions occurred two weeks later. A further investigation led to the identification of an A. abstrusus infection that was treated with fenbendazole. Ten days after the treatment the cat became negative for A. abstrusus and further analyses performed in the followings 2 months showed improvement of the animal's pulmonary condition and negative results at the faecal examinations. These findings indicate that veterinarians should include aelurostrongylosis in the differential diagnosis of feline respiratory distress even in non-endemic regions and should perform appropriate diagnostics procedures in the presence of compatible signs.

Computed tomography, radiology and echocardiography in cats naturally infected with Aelurostrongylus abstrusus

Objectives The aims of the study were to describe the radiographic and computed tomographic features in cats naturally infected with Aelurostrongylus abstrusus, and to identify signs of pulmonary hypertension with echocardiography. Methods Fourteen cats positive on Baermann test for A abstrusus were included in the study. All cats underwent thoracic radiography, CT and echocardiography. Results The most common clinical signs were coughing (10/14) and dyspnoea (5/14). Radiographic findings included a generalised unstructured interstitial pulmonary pattern (8/14), mixed bronchointerstitioalveolar pattern (3/14) and bronchointerstitial pattern with bronchial wall thickening (3/14). Sternal lymphadenopathy was detected on thoracic radiographs in six cats. On CT, features were mixed bronchointerstitioalveolar pattern with ground-glass appearance in six cats, interstitioalveolar with multiple pulmonary nodules in five, interstitial ground-glass infiltrates in three, regional lymph node enlargement in 11 (10 sternal, three cranial mediastinal and three tracheobronchial lymph nodes) and subpleural thickening in four. None of the thoracic radiographs revealed subpleural thickening. In all cases, pulmonary vessels were normal in terms of size, shape and attenuation on both radiography and CT. Pulmonary hypertension and cardiac abnormalities were not observed in any cat during echocardiography. Conclusions and relevance CT provided a more thorough characterisation of pulmonary and mediastinal lesions compared with thoracic radiographs in cats naturally infected with A abstrusus. Although feline aelurostrongylosis has been previously associated with histopathological lesions in lung arteries, in this cohort clinical evidence of pulmonary hypertension was not documented.

Vasoproliferative process resembling pulmonary capillary hemangiomatosis in a cat

BACKGROUND

Pulmonary capillary hemangiomatosis is a rare, vascular obstructive disorder that uniformly causes pulmonary arterial hypertension. Clinically, pulmonary capillary hemangiomatosis is indistinguishable from primary pulmonary arterial hypertension and histology is required for definitive diagnosis. The distinctive histologic feature of pulmonary capillary hemangiomatosis is non-malignant extensive proliferation of capillaries in the alveolar septae. Vasodilator treatment of humans with primary arterial hypertension due to pulmonary capillary hemangiomatosis can result in fatal acute pulmonary edema. Computed tomography is thus critical to discern pulmonary capillary hemangiomatosis from other causes of pulmonary arterial hypertension prior to vasodilator therapy. This is the first report of a vasoproliferative process resembling pulmonary capillary hemangiomatosis in the feline species.

CASE PRESENTATION

A 15-year-old, male castrated, domestic shorthair cat presented for persistent labored breathing presumptively due to congestive heart failure despite treatment with diuretics for 7 days. Echocardiography showed evidence of hypertrophic cardiomyopathy with severe pulmonary hypertension; however, a normal sized left atrium was not consistent with congestive heart failure. Thoracic computed tomography was performed and showed evidence of diffuse ill-defined nodular ground glass opacities, enlarged pulmonary arteries, and filling defects consistent with pulmonary thromboembolism. The cat acutely decompensated after a single dose of sildenafil and was euthanized. Histopathology of the lungs showed severe multifocal alveolar capillary proliferation with respiratory bronchiolar infiltration, marked type II pneumocyte hyperplasia and multifocal pulmonary arterial thrombosis.

CONCLUSION

This is the first description in a cat of a vasoproliferative disorder resembling pulmonary capillary hemangiomatosis complicated by multifocal pulmonary arterial thrombosis. Inspiratory and expiratory ventilator-driven breath holds with angiography revealed lesions predominantly characterized by ground glass opacification and vascular filling defects with absence of air trapping. The results from this report suggest that, as in humans, the cat can develop a pulmonary capillary hemangiomatosis-like disease in which vasodilator therapy to address pulmonary hypertension may lead to fatal pulmonary edema.

Respiratory distress associated with lungworm infection in a kitten

CASE SUMMARY

A 5-month-old feral kitten developed worsening respiratory signs, including tachypnea, coughing and wheezing after standard anthelmintic treatment with fenbendazole at a local shelter. The kitten was referred to the University of California, Davis, William R Pritchard Veterinary Medicine Teaching Hospital for further evaluation. Thoracic radiographs revealed a severe diffuse bronchointerstitial pattern with bronchial cuffing, ill-defined nodules and lymphadenomegaly. Differentials included infectious etiologies such as toxoplasmosis, feline infectious peritonitis and cryptococcosis. Parasitic infection was considered less likely, owing to previous anthelmintic treatment. Bronchoalveolar lavage revealed marked neutrophilic and eosinophilic inflammation, and parasitic larvae were observed in a swab of trachea mucus. PCR confirmed the larvae as Aelurostrongylus abstrusus. The kitten recovered with two more rounds of anthelmintic treatment.

RELEVANCE AND NOVEL INFORMATION

Parasitic pneumonia should be considered as a cause of respiratory distress in kittens and cats. Lungworm infections have been more commonly reported in free-roaming young and adult cats, but cannot be excluded as a differential diagnosis in cats from varied environments and in kittens. Kittens appear to be especially sensitive to lungworm infections, manifested by the development of more severe clinical signs; thus lungworm infection should always be considered when presented with a kitten in respiratory distress. In the absence of cytologic confirmation of infection via bronchoalveolar lavage or oropharyngeal swab, PCR provides a valuable means for identification of lungworms, such as A abstrusus and Troglostrongylus brevior.

Updates on feline aelurostrongylosis and research priorities for the next decade

Feline aelurostrongylosis, caused by the metastrongyloid nematode Aelurostrongylus abstrusus, is an important gastropod-borne parasitic lung disease in cats. Infection with A. abstrusus is widespread globally, but the increasing awareness of this parasite and the advent of more sensitive diagnostics have contributed to the apparent increase in its prevalence and geographic expansion. Clinical features may range in severity from subclinical to life-threatening respiratory disease. Parasitological standard techniques, such as visualization of the nematode first larval stage in faecal and respiratory (bronchial mucus or pleural fluid) samples, remain the mainstays of diagnosis. However, diagnosis is evolving with recent advances in serological and molecular testing, which can improve the time to initiation of effective anthelmintic therapy. Despite numerous anthelmintics that are now available as treatment options, the role of host immunity and lifestyle factors in selecting cats that may benefit from more targeted anthelmintic prophylaxis or treatment practice remains unclear and is likely to guide therapeutic choices as newer data become available. This review summarizes the biology, epidemiology, pathophysiology, diagnosis and treatment options currently available for feline aelurostrongylosis.

Partial anomalous pulmonary venous connection with suspected pulmonary hypertension in a cat

Partial anomalous pulmonary venous connection has previously been reported in the dog, but never in a cat. A 14-month-old Devon Rex cat was presented for echocardiography to evaluate a heart murmur noticed during a routine examination. The pertinent finding was right-sided cardiomegaly in the absence of an atrial septal defect or tricuspid regurgitation; pulmonary hypertension was suspected. A thoracic computed tomographic angiography study identified a partial anomalous pulmonary venous connection with the lobar veins of the left caudal, right middle, right caudal and accessory lung lobes draining into the caudal vena cava. The resultant volume overload is an easily overlooked differential diagnosis for right-sided cardiac enlargement. This is the first such report of this anomaly in a cat.

Diagnosis and management of lungworm infections in cats: Cornerstones, dilemmas and new avenues

PRACTICAL RELEVANCE

Respiratory parasites infecting domestic cats are attracting increased attention in feline clinical practice. In addition to the most commonly recognised 'cat lungworm' Aelurostrongylus abstrusus, Troglostrongylus brevior and Capillaria aerophila are now considered important pathogens of the respiratory tract of cats.

GLOBAL IMPORTANCE

These parasites are being increasingly diagnosed in several regions of the world and a continuous update on epidemiological changes and advances in diagnosis and control is of practical importance.

AIMS

This article reviews current knowledge of lungworms affecting cats, with a special focus on recent insights into diagnosis and management of the diseases they cause. The article also explores some potential new avenues for control of feline parasitic respiratory diseases, and highlights some key areas requiring further research.

Felid Lungworms and Heartworms in Italy: More Questions than Answers?

Nematodes infecting the cardiorespiratory system of cats have recently stimulated high scientific interest. Over the past few years, different aspects of these parasites have been clarified and various issues elucidated. This increased knowledge has improved awareness on this topic but, at the same time, some dilemmas have not been solved and new questions have been raised. In this review, we underline and discuss current knowledge of, and new doubts relating to, feline lungworms and heartworms, with the aim of stimulating new studies to fill gaps of basic (i.e., epidemiology and biology) and applied (i.e., clinical aspects) knowledge of the old and new parasites affecting the cardiorespiratory system of cats.

Irreversible pulmonary hypertension associated with Troglostrongylus brevior infection in a kitten

A four month-old kitten was referred at the Veterinary Teaching Hospital of Teramo, Italy. Physical examination, echocardiography, thoracic radiography, copromicroscopy and biomolecular assays led to a diagnosis of severe parasitic bronchopneumonia by Troglostrongylus brevior complicated by pulmonary hypertension. A single administration of a spot on solution containing imidacloprid 10%/moxidectin 1% was effective in stopping larval shedding but clinical, radiographic and echocardiographic signs of bronchopneumonia and pulmonary hypertension still persisted after further follow-ups.While cases of pulmonary hypertension are known in infections by Aelurostrongylus abstrusus, this is the first report of irreversible pulmonary hypertension in a kitten with troglostrongylosis.

Lungworm disease in cats: ABCD guidelines on prevention and management

OVERVIEW

Cardiopulmonary nematodes are emerging parasites of cats in Europe. A number of helminth parasites may be involved. The most prevalent lungworm in domestic cats is Aelurostrongylus abstrusus. Oslerus rostratus and Troglostrongylus species are found mainly in wild cats. The trichurid Capillaria aerophila has a low host specificity and is not uncommon in cats. Additionally the lung flukes Paragonimus species are reported in many species outside of Europe, including cats.

CLINICAL SIGNS

Lungworm infections may be asymptomatic, or cause mild to severe respiratory signs, dependent on the worm species and burden; mixed infections are observed. Kittens can be vertically infected and may develop a more severe disease. Affected cats show a productive cough, mucopurulent nasal discharge, tachypnoea, dyspnoea and, in severe cases, respiratory failure and death.

MANAGEMENT

Early diagnosis and treatment greatly improves the prognosis. First-stage larvae can be easily detected in fresh faecal samples; the Baermann migration method is the enrichment technique of choice, but takes 24 h. Lungworm larvae can be found in tracheal swabs and bronchoalveolar lavage fluid, but with less sensitivity than in faeces. Molecular methods have been developed that exhibit high specificity and sensitivity, and allow diagnosis in the prepatent phase. Treatment options include fenbendazole paste, milbemycin oxime/praziquantel and various spot-on formulations. Severe cases should receive prompt medical care in an intensive care unit.

PREVENTION

Avoiding predation is at present the only preventive measure for pulmonary worms with indirect life cycles.

ZOONOTIC RISK

C aerophila has zoonotic potential, causing severe pulmonary disease in humans. Some Paragonimus species are also of zoonotic concern.

Use of sildenafil citrate in a cat with Eisenmenger’s syndrome and an atrial septal defect

A 2-year-old male neutered Siamese cat presenting with weakness and dyspnoea was diagnosed with an atrial septal defect and pulmonary hypertension, which resulted in right-to-left shunting (Eisenmenger’s syndrome). The cat was treated with sildenafil (0.25–0.6 mg/kg) for 10 months. There were no apparent treatment-related adverse effects. Improvement in clinical signs was noted, although increasing doses of sildenafil were required. After 10 months the cat significantly deteriorated and was euthanased.

Gross and histopathological changes associated with Aelurostrongylus abstrusus and Troglostrongylus brevior in a kitten

Aelurostrongylus abstrusus affects the respiratory system of domestic cats worldwide, causing different clinical signs. Recently, Troglostrongylus brevior, a parasite found only in feral and wild animals until 2010, has been regarded as a cause of potentially severe bronchopneumonia in domestic cats. The life cycle of both nematodes involves the same intermediate (i.e. land mollusks) and paratenic hosts (i.e. lizards, birds and small mammals). Biological and epidemiological drivers may cause the spreading of A. abstrusus along with a possible emergence of T. brevior from marginal areas and limited hosts. Given the merit in increasing knowledge on these potentially emerging nematodes, the present paper describes clinical features and the first post mortem gross and histopathological observations in a case of mixed infection by A. abstrusus and T. brevior in a kitten.

Feline lungworms: what a dilemma

Aelurostrongylus abstrusus is regarded as the major lungworm infecting Felis catus, although other, albeit poorly studied, nematodes have been described from the respiratory system of domestic cats. Recent records of these neglected parasites have renewed the attention of the scientific community, but their actual role in respiratory disease in cats is blurred. The epidemiology, pathogenic role, and diagnosis of Troglostrongylus spp., Oslerus rostratus, and Capillaria aerophila in domestic cats are far from being clarified. Indeed, recent studies have provided novel information but have also given rise to relevant doubts. We discuss here the state of current knowledge regarding felid lungworms together with the dilemmas recently roused in the scientific literature.