Angiostrongylosis in dogs with negative fecal and in-clinic rapid serological tests: 7 Cases (2013-2017)

Control line failure in Angiostrongylus vasorum point-of-care serology test in dogs with angiostrongylosis due to suspected hook effect

OBJECTIVES

Angiostrongylosis is a significant differential for a diverse range of clinical signs in dogs, many of whom present acutely and sometimes with fatal consequences. Point-of-care diagnostic assays include a commercially available Angiostrongylus vasorum qualitative direct lateral flow assay.

MATERIALS AND METHODS

Case records from one referral centre from dogs with an invalid A. vasorum lateral flow assay, comprising an absent control line alongside a visible test line, were reviewed. As control line failure was hypothesised to be due to antigen excess; where available the A. vasorum lateral flow assay was repeated using dilutions of the original serum.

RESULTS

Six dogs had an invalid A. vasorum lateral flow assay result. Five dogs had presented with acute-onset, severe clinical disease consistent with angiostrongylosis, and one dog was a clinically healthy in-contact. Clinical suspicion of angiostrongylosis was confirmed using alternative diagnostic testing and/or response to treatment. Repetition of the A. vasorum lateral flow assay, in four cases, using diluted plasma (10% to 12.5% v/v) resulted in the appearance of a control line alongside the visible test line.

CLINICAL SIGNIFICANCE

A heavy burden of A. vasorum infection resulting in angiostrongylosis should be suspected in dogs with compatible clinical signs and an invalid A. vasorum lateral flow assay result due to control failure alongside a visible test line. Repetition of the test with a diluted serum may be considered to account for the hook effect, also known as the postzone phenomenon, as a possible cause.

A Taq-Man-based multiplex quantitative PCR for the simultaneous detection and quantification of Angiostrongylus vasorum, Crenosoma vulpis, and species of respiratory capillarids in canids

In recent years, Angiostrongylus vasorum, Crenosoma vulpis, Eucoleus aerophilus (syn. Capillaria aerophila) and Eucoleus boehmi (syn. Capillaria boehmi), commonly referred to as canine lungworms, have gained a growing interest worldwide as the result of their geographical expansion. Each of these nematode species differs considerably in its biology and pathogenicity. Despite their impact on dogs' health, these parasites are often underdiagnosed owing to diagnostic challenges. Here, we describe the development and validation of a Taq-Man-based multiplex quantitative PCR (qPCR) for the simultaneous detection of the main species of canine lungworms in faeces of infected dogs. Using 10-fold serial dilutions of synthetic gene block fragments containing individual sequence targets of each lungworm species, the analytical sensitivity of the assay ascertained was 1.84 ng/μl for A. vasorum, 3.08 ng/μl for C. vulpis and 0.79 ng/μl for Eucoleus spp. The sensitivity of the assays and their ability to detect mixed species infections were compared with microscopy-based techniques (faecal floatation and Baermann technique) applied to faecal samples submitted for lungworm testing through an accredited diagnostic laboratory at the Institute of Parasitology, University of Zurich, Switzerland, and from community dogs as part of a research project on canine endoparasites in Cambodia. The multiplex qPCR displayed high diagnostic sensitivity (42/46, 91.3%; 95% Confidence Interval (CI): 79.1-97.1%) and a diagnostic specificity of 100% (45/45, 95% CI: 90.6-100%), and was able to detect 42.9% additional mixed lungworm species infections compared with microscopy-based methods. Kappa statistics showed substantial agreement between the qPCRs and microscopy for mixed infections (κ = 0.72, 95% CI: 0.4-1) and Eucoleus spp. (κ = 0.65, 95% CI: 0.45-0.85) and almost perfect agreement for C. vulpis (κ = 0.85, 95% CI: 0.63-1) and A. vasorum (κ = 0.92, 95% CI: 0.84-1). This multiplex qPCR enables timely, accurate, and sensitive diagnosis of canine lungworm species in faecal samples and can be used to monitor the geographical distribution and emergence of these parasitic species, globally.

Allogenic blood patch pleurodesis for management of pneumothorax in a Cavalier King Charles Spaniel puppy with multiple pulmonary blebs and bullae

A 9‐week‐old male intact Cavalier King Charles Spaniel was presented for evaluation of acute onset dyspnea caused by left‐sided pneumothorax. Thoracic computed tomography (CT) identified multiple pulmonary bullae and blebs in multiple lung lobes. Rupture of ≥1 pulmonary blebs or bullae, precipitated by low impact trauma, was the suspected cause of pneumothorax. A volume of 7.5 mL/kg of fresh whole blood was collected from a type‐matched donor dog and administered into the left pleural space using a thoracostomy tube. The pneumothorax was successfully resolved and no adverse effects of blood patch pleurodesis were noted. The dog was clinically normal 12 months later.

Pneumothorax in a persistent canine Angiostrongylus vasorum infection

Canine angiostrongylosis is a gastropod-borne parasitosis caused by the cosmopolitan nematode Angiostrongylus vasorum. It is associated with cardiorespiratory disorders and eventually fatal coagulopathies. A 6-months-old female dog previously diagnosed with bronchopneumonia and pneumothorax, treated accordingly without success, was hospitalized for further treatment. Complementary diagnostics confirmed previous findings plus pneumomediastinum, thoracic exudate, leucocytosis, thrombocytosis, hypercoagulability, and hyperglobulinemia. Coprological analysis showed a severe patent A. vasorum infection. After the third daily fenbendazole administration, all A. vasorum larvae were found dead in follow-up coprological analyses while in intensive care. Upon release, the dog was monitored until full clinical recovery 3 months later. Up to date, A. vasorum infection-related pneumothorax was rarely described, particularly with full recovery of such a young patient. Thus, a parasitological aetiology should be considered for dogs with severe bronchopneumonia or pneumothorax, especially in Europe and South America where increasing numbers of canine angiostrongylosis cases call for enhanced awareness of veterinary practitioners.

Dorsal mediastinal haemorrhage in dogs: four cases (2010-2018)

OBJECTIVE

This retrospective case series describes the clinical presentation and CT findings of dogs with presumed mediastinal haemorrhage with no apparent identifiable underlying cause.

MATERIALS AND METHODS

Medical records were searched for dogs with presumed or suspected mediastinal haemorrhage of non-thymic origin. For all dogs, data on signalment, history, physical examination, treatment and outcome were collected by reviewing the medical records. Follow-up information was collected by telephone interviews with the owners and/or their primary-care veterinarians.

RESULTS

Four dogs were included. All survived to discharge with apparent resolution of the mediastinal haemorrhage (based on repeat imaging and/or clinical signs) with supportive treatment alone. Follow-up information was available from 2 months to 5 years following discharge, and none of the patients showed a recurrence of clinical signs during this period.

CLINICAL SIGNIFICANCE

This case series highlights that presumed haemorrhage into the mediastinum can occur in dogs without an obviously identifiable cause and, whilst rare, should be considered as a cause of dorsal mediastinal masses and may be successfully managed with supportive care alone.

Utility of thoracic ultrasonography in a rapid diagnosis of angiostrongylosis in young dogs presenting with respiratory distress

The nematode, Angiostrongylus vasorum is a nematode that lives in the pulmonary arteries of canids and has an obligate gastropod intermediate host. It can cause various clinical signs. with the two most common clinical scenarios consisting of acute respiratory distress and haemorrhagic diathesis, either separately or together. Younger dogs (< 2 years) are overrepresented, and dogs often show pulmonary granulomata (radiographically and pathologically). Thoracic ultrasonography offers a safe, rapid, commonly available, non-invasive means of assessing the lungs. We prospectively examined the utility of thoracic ultrasonography in the diagnosis of angiostrongylosis in 26 client-owned dogs <2 years old, presenting with respiratory distress. We identified small hypoechoic subpleural nodules in 15/26 dogs; 14 of these were subsequently confirmed to have angiostrongylosis by faecal Baermann concentration test, A. vasorum antigen testing or both. The remaining 11 dogs without subpleural nodules had negative faecal analysis and A. vasorum antigen testing and diagnosed with other respiratory diseases. This resulted in a sensitivity of 100% and a specificity of 92% for the detection of angiostrongylosis by thoracic ultrasonography in young dogs presenting with respiratory distress. Our results suggest that thoracic ultrasonography might offer a safe, rapid, relatively accurate diagnostic test for diagnosis of angiostrongylosis in young adult dogs with respiratory distress living in endemic areas.

First report of fatal autochthonous angiostrongylosis in a dog in Greece

Canine angiostrongylosis caused by Angiostrongylus vasorum is a life-threatening disease which is emerging in regions of Europe. Thus, there is the merit for a continuous epidemiological surveillance in dog populations. This is the first description of a clinical autochthonous case of canine angiostrongylosis in Greece. A 7-month-old, male, mixed-breed dog was presented with progressively worsening anorexia, respiratory distress, coughing, bleeding diathesis and succumbed four days post admission. Gross post mortem examination revealed numerous nodular fistulated lesions in the lungs, and pulmonary cytology and histopathology showed a verminous pyogranulomatous pneumonia. The definitive diagnosis was based on the morphological identification of first stage larvae (L1) retrieved in the feces by the Baermann method, the detection of the circulating antigen by an in-clinic test and the molecular identification of L1. This report underlines the epidemiological and clinical implications, as well as the infection risks when the index of clinical suspicion is low and the disease is unexpected in a country.

Angiostrongylosis in northeastern Italy: First report of two autochthonous fatal cases in dogs and first detection in a wild red fox

Canine angiostrongylosis is an emergent cardio-pulmonary gastropod-borne helminthic infection caused by the metastrongyloid nematode Angiostrongylus vasorum. Clinically, it is characterized by a wide spectrum of non-specific signs and the red fox serves as the most important reservoir for dog infections. In Italy, this disease has been well documented both in northwestern and central-southern regions, whereas it is apparently poorly recognized in the northeastern area of the country. This report describes the diagnostic findings of two autochthonous cases of fatal canine angiostrongylosis and of one case in a wild red fox detected in northeastern Italy. Reporting cases is relevant to clinicians in order to increase their awareness for the prompt diagnosis of a potentially life-threatening disease that may go unnoticed or misdiagnosed.

Respiratory Emergencies

Respiratory distress is commonly seen in dogs and cats presenting to the emergency room. Rapid identification of respiratory difficulty with strategic stabilization and diagnostic efforts are warranted to maximize patient outcome. This article focuses on the relevant anatomy and physiology of the respiratory system and the clinical recognition, stabilization, and initial diagnostic planning for small animal patients that present for respiratory emergencies.

Analysis of the lung microbiota in dogs with Bordetella bronchiseptica infection and correlation with culture and quantitative polymerase chain reaction

Infection with Bordetella bronchiseptica (Bb), a pathogen involved in canine infectious respiratory disease complex, can be confirmed using culture or qPCR. Studies about the canine lung microbiota (LM) are recent, sparse, and only one paper has been published in canine lung infection. In this study, we aimed to compare the LM between Bb infected and healthy dogs, and to correlate sequencing with culture and qPCR results. Twenty Bb infected dogs diagnosed either by qPCR and/or culture and 4 healthy dogs were included. qPCR for Mycoplasma cynos (Mc) were also available in 18 diseased and all healthy dogs. Sequencing results, obtained from bronchoalveolar lavage fluid after DNA extraction, PCR targeting the V1–V3 region of the 16S rDNA and sequencing, showed the presence of Bb in all diseased dogs, about half being co-infected with Mc. In diseased compared with healthy dogs, the β-diversity changed (P = 0.0024); bacterial richness and α-diversity were lower (P = 0.012 and 0.0061), and bacterial load higher (P = 0.004). Bb qPCR classes and culture results correlated with the abundance of Bb (r = 0.71, P < 0.001 and r = 0.70, P = 0.0022). Mc qPCR classes also correlated with the abundance of Mc (r = 0.73, P < 0.001). Bb infection induced lung dysbiosis, characterized by high bacterial load, low richness and diversity and increased abundance of Bb, compared with healthy dogs. Sequencing results highly correlate with qPCR and culture results showing that sequencing can be reliable to identify microorganisms involved in lung infectious diseases.

The 'French heartworm' in Greece: A countrywide serological survey of Angiostrongylus vasorum infection by combined detection of circulating antigens and specific antibodies

Angiostrongylus vasorum is a nematode of the superfamily Metastongyloidea and was first described in the south of France in the nineteenth century where its biology was extensively studied in the 1960ies, leading to the common use of the byname "the French heartworm". The life cycle of the parasite is indirect including slugs and snails as intermediate hosts, while the adults live in the right heart and pulmonary arteries. Since then, many studies have been conducted in different European countries. However, there is scant knowledge regarding the prevalence and distribution of this parasite in Greece. Therefore, the objective of the present study was to investigate the current seroprevalence of A. vasorum in dogs in Greece. Overall 1000 apparently healthy and randomly selected dogs, presented in veterinary clinics, were involved at national level (n = 66 locations). Individual serum samples were obtained and tested using two in-house ELISAs by combining the detection of specific antibodies against the parasite and of circulating antigens of A. vasorum. Overall, 3.0% (n = 30, CI 95% 2.1 to 4.3%) of the sampled dogs were seropositive to at least one of the two ELISAs: 0.4% (n = 4, CI 95% 0.2 to 1.0%) were positive by both ELISAs, while 1.0% (n = 10, CI 95% 0.5 to 1.8%) were seropositive only for specific antibodies and 1.6% (n = 16, CI 95% 1.0 to 2.6%) were antigen-positive only. This is the first multicentric seroepidemiological study about A. vasorum in dogs from Greece. We showed that this parasite circulates in the local canine population and further studies should be carried out to elucidate its significance in the country.

Irreversible Ocular Lesions in a Dog With Angiostrongylus Vasorum Infection

This report describes a 10-month-old dog with a sudden loss of vision and severe dyspnoea. The ocular examination revealed bilateral panuveitis, lens subluxation, secondary glaucoma, and retinal detachment. In addition, the ocular ultrasound showed in the vitreous body of the right eye, a small doubled-lined foreign body compatible with an intraocular parasite. Radiographs of the thorax revealed an increased opacity with mixed lung pattern (alveolar and bronchial) and thoracic ultrasonography showed several subpleural nodules. The presence of Angiostrongylus vasorum first stage larvae was confirmed with 324 larvae per gram of feces and an antigen test for the parasite (AngioDetect, IDEXX) also yielded a positive result. The severe and irreversible ocular lesions described in this case enhanced the complexity of the clinical picture of canine angiostrongylosis. Infection with the parasite should be included in the list of differential diagnoses for ocular uveitis to avoid potentially serious complications related to a missed or delayed diagnosis.

Angiostrongylosis in dogs with negative fecal and in-clinic rapid serological tests: 7 Cases (2013-2017)

BACKGROUND

Angiostrongylosis is considered as emerging disease in dogs in Belgium. Detection of first-stage larvae in feces using the Baermann method has an imperfect sensitivity.

OBJECTIVES

Investigation of efficacy of noninvasive blood and fecal diagnostic tests in comparison with PCR on bronchoalveolar lavage (BAL) material in a small series of coughing or dyspnoeic dogs naturally infected with Angiostrongylus vasorum.

ANIMALS

Seven dogs with angiostrongylosis.

METHODS

Retrospective study. Dogs with cough, exercise intolerance and dyspnea of 2- to 8-week duration. Diagnostic methods used included Baermann analysis, AngioDetect rapid assay, ELISAs for detection of circulating antigen and specific antibodies and qPCR on BAL material.

RESULTS

Baermann analysis, AngioDetect rapid assay, antigen ELISA, antibody ELISA, and qPCR on BAL material were positive in 3/7, 2/7, 3/6, 6/6, and 7/7 dogs, respectively. ELISA for antibodies or qPCR on BAL material were essential for definitive diagnosis in 3 dogs. Relative sensitivities of AngioDetect rapid assay, Baermann analysis, and ELISA for antigen detection were lower than 50% compared with ELISA for antibodies or qPCR on BAL material.

CONCLUSION AND CLINICAL IMPORTANCE

In this small clinical series, Baermann analysis and AngioDetect rapid assay failed to confirm the diagnosis in some dogs. Therefore, ELISA for antibody detection and qPCR on BAL material should strongly be considered in clinically suspected dogs when antigen detection methods (AngioDetect or ELISA) and Baermann analysis are negative.