Coagulation status in dogs with naturally occurring Angiostrongylus vasorum infection

First case of autochthonous Angiostrongylus vasorum infection in a Norwegian dog

A fifteen-month-old Pembroke Welsh corgi with respiratory distress, exercise intolerance, and moderate regenerative anemia was referred to The Norwegian University of Life Sciences, Small Animal Hospital.Hematology revealed moderate regenerative anemia without evidence of hemolysis. Thoracic radiographs showed a generalized mixed interstitial to alveolar lung pattern and enlarged pulmonary arteries. Changes suggestive of moderate pulmonary hypertension were noted on echocardiography. Baermann fecal diagnostic flotation identified large numbers of Angiostrongylus vasorum larvae, and the AngioDetect serological antigen test was positive. The dog was treated with a two-week course with fenbendazole (51 mg/kg q24h po) and topical imidacloprid/moxidectin (250 mg/62.5 mg) and a one-week course with sildenafil (0.45 mg/kg q12h po). Complete clinical, clinicopathological and echocardiographic resolution was observed after only four weeks. Rapid improvement of echocardiographic abnormalities in cases with suspected pulmonary hypertension is not usually reported in cases with angiostrongylosis.Infection with A. vasorum should be considered in dogs with respiratory signs and bleeding tendencies, even in countries with no endemic history or reported cases.

Clinical bleeding diathesis, laboratory haemostatic aberrations and survival in dogs infected with Angiostrongylus vasorum: 180 cases (2005-2019)

OBJECTIVES

Bleeding diathesis is a complication in dogs infected with Angiostrongylus vasorum. This retrospective study investigated clinical and laboratory haemostatic differences in A. vasorum-positive dogs with and without signs of bleeding and impact of bleeding on survival.

MATERIALS AND METHODS

Demographics, type of clinical bleeding, haematocrit and a range of haemostatic tests, including thromboelastography and derived velocity curves were retrospectively registered from A. vasorum-positive dogs. All parameters were compared between dogs with and without signs of bleeding using univariable analyses. Binomial and multinomial regression models were applied to examine specific indicators in the bleeding dogs. P-values were false discovery rate adjusted, and adjusted P<0.05 was considered significant.

RESULTS

One hundred and eighty dogs entered the study, including 65 dogs (36.1%) presenting with bleeding diathesis. Different types of cutaneous and mucosal bleeding were the most common clinical findings. Twenty dogs presented with neurological signs associated with intracranial and intra-spinal bleeding. One hundred and thirty-seven dogs had haematological and/or haemostatic laboratory analyses performed. Haematocrit, platelet count, thromboelastographic angle, maximum amplitude, global clot strength, maximum rate of thrombin generation and total thrombin generation were decreased, while prothrombin time was prolonged in bleeding dogs. Survival rate of bleeding dogs was lower at hospital discharge (76.9%) and 1 month after diagnosis (66.0%) than in dogs without signs of bleeding (94.8% and 90.1% at discharge and at 1 month, respectively).

CLINICAL SIGNIFICANCE

Several haemostatic aberrations were detected in A. vasorum-positive dogs with bleeding diathesis. Bleeding was identified as an important negative prognostic indicator in A. vasorum-positive dogs.

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.

Evaluation of the Effect of Induced Endotoxemia on ROTEM S® and Platelet Parameters in Beagle Dogs Anaesthetized with Sevoflurane

Endotoxemia is thought to induce severe changes in coagulation status. In this study, blood samples from six beagle dogs receiving 1 mg/kg E. coli lipopolysaccharide (LPS) intravenously were analyzed to describe the concurrent changes in platelet count, platelet function assessed with impedance thromboaggregometry, thromboelastometry and d-dimers during artificially induced endotoxemia and its therapy with fluids and vasopressors at five timepoints (baseline, after LPS and 30 mL/kg Ringer's acetate, during noradrenaline ± dexmedetomidine infusion, after a second fluid bolus and a second time after vasopressors). Results were analyzed for changes over time with the Friedman test, and statistical significance was set at p < 0.05. We found decreased platelet count and function and changes in all platelet-associated rotational thromboelastometry (ROTEM) variables indicating hypocoagulability, as well as increases in d-dimers indicating fibrinolysis within one hour of intravenous administration of LPS, with partial recovery of values after treatment and over time. The fast changes in platelet count, platelet function and ROTEM variables reflect the large impact of endotoxemia on the coagulation system and support repeated evaluation during the progress of endotoxemic diseases. The partial recovery of the variables after initiation of fluid and vasopressor therapy may reflect the positive impact of the currently suggested therapeutic interventions during septic shock in dogs.

Comparative biology of parasitic nematodes in the genus Angiostrongylus and related genera

The rise to prominence of some Angiostrongylus species through associated emerging disease in humans and dogs has stimulated calls for a renewed focus on the biology of this genus and three related genera. Although significant research efforts have been made in recent years these have tended to focus on individual species and specific aspects such as diagnosis and treatment of disease or new records of occurrence and hosts. This comprehensive review takes a comparative approach, seeking commonalities and differences among species and asking such questions as: Which species belong to this and to closely related genera and how are they related? Why do only some species appear to be spreading geographically and what factors might underlie range expansion? Which animal species are involved in the life cycles as definitive, intermediate, paratenic and accidental hosts? How do parasite larvae find, infect and develop within these hosts? What are the consequences of infection for host health? How will climate change affect future spread and global health? Appreciating how species resemble and differ from each other shines a spotlight on knowledge gaps and provides provisional guidance on key species characteristics warranting detailed study. Similarities exist among species, including the basic life cycle and transmission processes, but important details such as host range, climatic requirements, migration patterns within hosts and disease mechanisms differ, with much more information available for A. cantonensis and A. vasorum than for other species. Nonetheless, comparison across Angiostrongylus reveals some common patterns. Historically narrow definitive host ranges are expanding with new knowledge, combining with very broad ranges of intermediate gastropod hosts and vertebrate and invertebrate paratenic and accidental hosts to provide the backdrop to complex interactions among climate, ecology and transmission that remain only partly understood, even for the species of dominant concern. Key outstanding questions concern larval dynamics and the potential for transmission outside trophic relations, relations between infection and disease severity in different hosts, and how global change is altering transmission beyond immediate impacts on development rate in gastropods. The concept of encounter and compatibility filters could help to explain differences in the relative importance of different gastropod species as intermediate hosts and determine the importance of host community composition and related environmental factors to transmission and range. Across the group, it remains unclear what, physiologically, immunologically or taxonomically, delimits definitive, accidental and paratenic hosts. Impacts of infection on definitive host fitness and consequences for population dynamics and transmission remain mostly unexplored across the genus. Continual updating and cross-referencing across species of Angiostrongylus and related genera is important to synthesise rapid advances in understanding of key traits and behaviours, especially in important Angiostrongylus species that are emerging causative agents of disease in humans and other animals.

Case report: Intracranial and spinal subarachnoid hemorrhage in a dog with Angiostrongylosis

A 1-year-old male intact Staffordshire terrier, born and raised in the Netherlands, was presented with a 3-week history of progressive lethargy and spinal, predominantly cervical, hyperesthesia. Other than hyperthermia and cervical hyperesthesia, general and neurological examination did not reveal any abnormalities. Comprehensive hematological and biochemical tests were considered normal. Magnetic resonance imaging of the craniocervical region revealed heterogeneity of the subarachnoid space, characterized by pre-contrast T1W hyperintensity, corresponding to a T2* signal void. Extending from the caudal cranial fossa to the level of the third thoracic vertebra, there were uneven patchy extra-parenchymal lesions that caused mild spinal cord compression, most marked at the level of C2. At this level, the spinal cord showed an ill-defined hyperintense T2W intramedullary lesion. Mild intracranial and spinal meningeal contrast enhancement was evident on post-contrast T1W images. Subarachnoid hemorrhage was suspected, and further diagnostic tests including Baermann coprology resulted in a diagnosis of hemorrhagic diathesis caused by an Angiostrongylus vasorum infection. The dog rapidly responded to treatment with corticosteroids, analgesic medication, and antiparasitic treatment. Follow-up over 6 months yielded complete clinical remission and repeatedly negative Baermann tests. This case report details clinical and magnetic resonance imaging findings in a dog with subarachnoid hemorrhage associated with an Angiostrongylus vasorum infection.

Gurltia paralysans: A Neglected Angio-Neurotropic Parasite of Domestic Cats (Felis catus) and Free-Ranging Wild Felids (Leopardus spp.) in South America

Gurltia paralysans is a neglected and re-emerging metastrongyloid angio-neurotropic nematode causing severe chronic meningomyelitis in domestic cats (Felis catus) as well as in free-ranging small wild felids such as kodkods (Leopardus guigna), margays (Leopardus wiedii) and the northern tiger cat (Leopardus triginus) in South America. Within these definitive hosts (DH), adult males and females of G. paralysans parasitize the leptomeningeal veins of the subarachnoid space and/or the meningeal veins of spinal cord parenchyma, inducing vascular alterations. Feline gurltiosis has been associated with progressive thrombophlebitis of the meningeal veins, resulting in ambulatory paraparesis, paraplegia, ataxia, hindlimb proprioceptive deficit, uni- or bilateral hyperactive patellar reflexes, faecal and urinary incontinence, and tail paralysis. The complete life cycle of G. paralysans has not been elucidated yet, but most probably involves gastropods as obligate intermediate hosts (IH). In terms of epidemiology, G. paralysans infections in domestic and wild felids are scattered around various South American countries, with hyperendemic areas in southern parts of Chile. Etiological diagnosis of G. paralysans still represents a challenge for clinicians due to a lack of evidence of the excretion of either eggs or larvae in faeces or in other body fluids. Diagnosis is based on clinical neurological signs, imaging findings through computed tomography (CT), myelography, magnetic resonance imaging (MRI), and post mortem examination. Nonetheless, novel diagnostic tools have been developed, including semi-nested PCR for detecting circulating G. paralysans DNA in the cerebrospinal fluid, serum and blood samples as well as in serological diagnostic kits detecting parasite-derived antigens, but these need validation for routine usage. The hypothetical life cycle of G. paralysans is addressed in this article, including the exogenous stages (i.e., eggs, and first- (L1), second- (L2) and third-stage (L3) larvae) and obligate gastropod IH and/or paratenic hosts (PH), and we propose possible anatomical migration routes of infective L3 that reach the leptomeningeal veins in vivo. Finally, the pro-inflammatory endothelium- and leukocyte-derived innate immune reactions of the host against G. paralysans, which most likely result in thrombophlebitis and meningomyelitis, are briefly touched on.

Hemostatic Dysfunction in Dogs Naturally Infected with Angiostrongylus vasorum—A Narrative Review

This narrative review aims to describe Angiostrongylus vasorum-induced hemostatic dysfunction of dogs with emphasis on clinical and laboratory findings as well as potential therapeutic strategies for the bleeding patient. Canine angiostrongylosis (CA) is a disease with potentially high morbidity and mortality in endemic areas and with fatal outcome often associated with either severe respiratory compromise, pulmonary hypertension and right-sided heart failure, or hemostatic dysfunction with severe bleeding. The most common signs of hemorrhage are hematomas, petecchiation, ecchymoses, oral mucosal membrane bleeding and scleral bleeding, while intracranial and pulmonary hemorrhage are among the most severe. The pathophysiological mechanisms underlying hemostatic dysfunction in these patients are presently researched. While the larval effect on platelets remains unknown, the parasite appears to induce dysregulation of hemostatic proteins, with studies suggesting a mixture of pro-coagulant protein consumption and hyperfibrinolysis. Importantly, not all dogs display the same hemostatic abnormalities. Consequently, characterizing the hemostatic state of the individual patient is necessary, but has proven difficult with traditional coagulation tests. Global viscoelastic testing shows promise, but has limited availability in general practice. Treatment of A. vasorum-infected dogs with hemostatic dysfunction relies on anthelmintic treatment as well as therapy directed at the individual dog’s specific hemostatic alterations.

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.

Angiostrongylus vasorum in Estonia: Multi-center study in dogs with clinical signs suggestive of canine angiostrongylosis, survey of potential risk behaviors among the dogs, and questionnaire survey of knowledge about the parasite among veterinarians

Angiostrongylus vasorum is a parasite that can cause life-threatening disease in dogs. In recent years, A. vasorum has been reported spreading into new areas, in particular towards northeastern Europe. Despite being detected in wildlife in Estonia, no studies have focused on A. vasorum in domestic dogs in the country. We conducted a multi-center study in 2018-2019: at eight small animal clinics, altogether 115 dogs that had clinical signs that could be suggestive of canine angiostrongylosis were enrolled for testing using a commercial A. vasorum antigen detection test. In addition, we collected information on potential risk behaviors for acquiring A. vasorum infection - eating potential intermediate hosts and paratenic hosts - among the dogs, using a questionnaire for dog owners. Moreover, we surveyed knowledge about A. vasorum among veterinarians authorized to work in Estonia. None (0.0%, 95% confidence interval 0.0-2.6) of the 114 dogs included in the study tested A. vasorum antigen positive. Two (2.0%) of the 102 dogs included in the risk behavior analysis had been seen to eat slugs and/or snails, and this behavior was considered possible for further 17 (16.7%) of the dogs. Four (3.9%) of the dogs had been seen to eat frogs, and this behavior was considered possible for further 14 (13.7%) of the dogs. Thirty-eight (90.5%) of the 42 veterinarians who participated in the questionnaire survey selected the correct host and 28 (66.7%) selected the correct vectors of the parasite, from the provided options. Our results indicate that A. vasorum was either not established or not common in dogs in Estonia in 2018-2019, but this needs to be interpreted with caution due to the limited sample size, possible false negative results in recently infected dogs and the limited sensitivity of the test applied. Most local veterinarians seemed to know the parasite, and this awareness and knowledge among veterinarians should be maintained and further improved. Taken the presence of the parasite in local wildlife, it is prudent to include A. vasorum infection in the list of differential diagnoses for dogs with clinical signs that could be suggestive of canine angiostrongylosis in Estonia.

The Angiostrongylus vasorum Excretory/Secretory and Surface Proteome Contains Putative Modulators of the Host Coagulation

Angiostrongylus vasorum is a cardiopulmonary nematode of canids and is, among others, associated with bleeding disorders in dogs. The pathogenesis of such coagulopathies remains unclear. A deep proteomic characterization of sex specific A. vasorum excretory/secretory proteins (ESP) and of cuticular surface proteins was performed, and the effect of ESP on host coagulation and fibrinolysis was evaluated in vitro. Proteins were quantified by liquid chromatography coupled to mass spectrometry and functionally characterized through gene ontology and pathway enrichment analysis. In total, 1069 ESP (944 from female and 959 from male specimens) and 1195 surface proteins (705 and 1135, respectively) were identified. Among these were putative modulators of host coagulation, e.g., von Willebrand factor type D domain protein orthologues as well as several proteases, including serine type proteases, protease inhibitors and proteasome subunits. The effect of ESP on dog coagulation and fibrinolysis was evaluated on canine endothelial cells and by rotational thromboelastometry (ROTEM). After stimulation with ESP, tissue factor and serpin E1 transcript expression increased. ROTEM revealed minimal interaction of ESP with dog blood and ESP did not influence the onset of fibrinolysis, leading to the conclusion that Angiostrongylus vasorum ESP and surface proteins are not solely responsible for bleeding in dogs and that the interaction with the host's vascular hemostasis is limited. It is likely that coagulopathies in A. vasorum infected dogs are the result of a multifactorial response of the host to this parasitic infection.

Fox Serum Proteomics Analysis Suggests Host-Specific Responses to Angiostrongylus vasorum Infection in Canids

Dogs infected with the cardiopulmonary nematode Angiostrongylus vasorum may suffer from respiratory distress and/or bleeding disorders. Descriptions of clinical signs in foxes are rare, despite high prevalence. To evaluate the impact of infection on coagulation and immune response, serum proteins from eight experimentally infected foxes before and after inoculation (day 0, 35, 84, 154) were subjected to differential proteomic analyses based on quantitative data and compared to available data from dogs. The number of proteins with differential abundance compared to the uninfected baseline increased with chronicity of infection. Bone marrow proteoglycan, chitinase 3-like protein 1 and pulmonary surfactant-associated protein B were among the most prominently increased proteins. The abundance of several proteins involved in coagulation was decreased. Enriched pathways obtained from both increased and decreased proteins included, among others, "platelet degranulation" and "haemostasis", and indicated both activation and suppression of coagulation. Qualitative comparison to dog data suggests some parallel serum proteomic alterations. The comparison, however, also indicates that foxes have a more adequate immunopathological response to A. vasorum infection compared to dogs, facilitating persistent infections in foxes. Our findings imply that foxes may be more tolerant to A. vasorum infection, as compared to dogs, reflecting a longer evolutionary host-parasite adaptation in foxes, which constitute a key wildlife reservoir.

Coagulation Status in Dogs Naturally Infected with Angiostrongylus vasorum

Angiostrongylus vasorum infection has been associated with coagulopathies including hyperfibrinolysis. We compared coagulation status including thromboelastometry (ROTEM) parameters in dogs naturally infected with A. vasorum versus healthy dogs to determine clinicopathological parameters associated with bleeding, hypocoagulopathy, and hyperfibrinolysis. Clinical signs, white blood cell count, platelet count, hematocrit, plasmatic coagulation tests (PT, aPTT, fibrinogen concentration), D-dimer, and ROTEM S parameters (Ex-tem, In-tem, Fib-tem, Ap-tem) were analysed and compared between bleeding, nonbleeding, and control dogs and between hypo- and normocoagulable animals. Clinical signs of bleeding were present in 6/9 (67%) hypocoagulable and 1/9 (11%) normocoagulable dogs. PT, fibrinogen concentration, and several ROTEM parameters were significantly different between hypocoagulable and normocoagulabe A. vasorum infected dogs. Hyperfibrinolysis was identified in 44% of infected dogs and was significantly more common in bleeding and hypocoagulable dogs. Hyperfibrinolysis was significantly associated with low MCFFib-tem but not with low fibrinogen concentration or increased D-dimers. CFTEx-tem > 248 swas 100% sensitive and 89% specific to predict hyperfibrinolysis. Hyperfibrinolysis, hypocoagulability and bleeding are common in A. vasorum infected dogs. Only Ex-tem and Fib-tem parameters and potentially PT were associated with bleeding or hypocoagulability. Ex-tem analysis enables detection of bleeding, hypocoagulability and hyperfibrinolysis within minutes.

Canine Angiostrongylus vasorum-Induced Early Innate Immune Reactions Based on NETs Formation and Canine Vascular Endothelial Cell Activation In Vitro

Simple Summary

Angiostrongylus vasorum is a cardiopulmonary nematode that affects canids, residing in the pulmonary artery and right atrium/ventricle. Due to its location, the parasite will have a close interaction with the different components of the innate immune system, including endothelial cells and polymorphonuclear neutrophils (PMN). Here we evaluated the expression of adhesion molecules of canine aortic endothelial cells (CAEC), and NETs formation by co-culture of freshly isolated canine PMN with A. vasorum L3. Overall, we found distinct inter-donor variations in adhesion molecule expression among CAEC isolates. Additionally, PMN and A. vasorum co-culture induced NETs release without affecting larval viability.

Abstract

Due to its localization in the canine blood stream, Angiostrongylus vasorum is exposed to circulating polymorphonuclear neutrophils (PMN) and the endothelial cells of vessels. NETs release of canine PMN exposed to A. vasorum infective stages (third stage larvae, L3) and early pro-inflammatory immune reactions of primary canine aortic endothelial cells (CAEC) stimulated with A. vasorum L3-derived soluble antigens (AvAg) were analyzed. Expression profiles of the pro-inflammatory adhesion molecules ICAM-1, VCAM-1, P-selectin and E-selectin were analyzed in AvAg-stimulated CAEC. Immunofluorescence analyses demonstrated that motile A. vasorum L3 triggered different NETs phenotypes, with spread NETs (sprNETs) as the most abundant. Scanning electron microscopy confirmed that the co-culture of canine PMN with A. vasorum L3 resulted in significant larval entanglement. Distinct inter-donor variations of P-selectin, E-selectin, ICAM-1 and VCAM-1 gene transcription and protein expression were observed in CAEC isolates which might contribute to the high individual variability of pathological findings in severe canine angiostrongylosis. Even though canine NETs did not result in larval killing, the entanglement of L3 might facilitate further leukocyte attraction to their surface. Since NETs have already been documented as involved in both thrombosis and endothelium damage events, we speculate that A. vasorum-triggered NETs might play a critical role in disease outcome in vivo.

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.

Gross, microscopic, radiologic, echocardiographic and haematological findings in rats experimentally infected with Angiostrongylus cantonensis

Although the gross and microscopic pathology in rats infected with Angiostrongylus cantonensis has been well described, corresponding changes detected using diagnostic imaging modalities have not been reported. This work describes the cardiopulmonary changes in mature Wistar rats chronically infected with moderate burdens of A. cantonensis using radiology, computed tomography (CT), CT angiography, echocardiography, necropsy and histological examinations. Haematology and coagulation studies were also performed. Thoracic radiography, CT and CT angiography showed moderately severe alveolar pulmonary patterns mainly affecting caudal portions of the caudal lung lobes and associated dilatation of the caudal lobar pulmonary arteries. Presumptive worm profiles could be detected using echocardiography, with worms seen in the right ventricular outflow tract or straddling either the pulmonary and/or the tricuspid valves. Extensive, multifocal, coalescing dark areas and multiple pale foci affecting the caudal lung lobes were observed at necropsy. Histologically, these were composed of numerous large, confluent granulomas and fibrotic nodules. Adult worms were found predominantly in the mid- to distal pulmonary arteries. An inflammatory leukogram, hyperproteinaemia and hyperfibrinogenaemia were found in most rats. These findings provide a comparative model for A. cantonensis in its accidental hosts, such as humans and dogs. In addition, the pathological and imaging changes are comparable to those seen in dogs infected with Angiostrongylus vasorum, suggesting rats infected with A. cantonensis could be a model for dogs with A. vasorum infection.

Quantitative proteomics analysis of Angiostrongylus vasorum-induced alterations in dog serum sheds light on the pathogenesis of canine angiostrongylosis

Blood contains hundreds of proteins, reflecting ongoing cellular processes and immune reactions. Infections with the blood-dwelling cardiopulmonary nematode Angiostrongylus vasorum in dogs manifest with a broad spectrum of clinical signs including respiratory distress, bleeding diathesis and neurological signs, and are associated with a perturbed blood protein profile in dogs. However, current knowledge does not completely explain the observed pathologies induced by A. vasorum infections, including bleeding disorders. Using sera from experimentally infected dogs, dog serum proteome was analysed by quantitative mass spectrometry methods over several time points before and after inoculation. Following computational analysis, we identified 139 up- and downregulated proteins after infection (log2 ratio cut-off ≥ 1.0; q-value ≤ 0.05). Among upregulated proteins were chitinase 3-like 1 and pulmonary surfactant-associated protein B (log2 fold-changes ≥ 5). Pathway enrichment revealed the complement (especially the lectin pathway) and coagulation cascades as significantly affected upon analysis of downregulated proteins. Among them were mannan-binding lectin serine peptidases, ficolin, and coagulation factor XIII-B. These results bring new elements towards understanding the underlying pathomechanisms of bleeding diatheses observed in some A. vasorum-infected dogs.

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.

Abnormal platelet activity in dogs and cats - impact and measurement

Abnormal platelet activity can either lead to bleeding tendencies or inappropriate thrombus formation and can occur secondarily to a wide variety of disease processes, with a range of clinical consequences and severity. This article will discuss the pathophysiology of platelet function abnormalities and consider a logical diagnostic approach applicable to veterinary practice. Recent advances in platelet function testing will then be discussed, with regards to detection of platelet dysfunction and tailoring of pharmacological manipulation. Although many of these tests are still confined to research or academic institutions, techniques for indirectly assessing platelet function are starting to become more widely available. Although we still require further research to develop guidelines for the use of these tests in clinical decision-making, the recent advances in this field are an exciting step forward in being able to detect and manage platelet dysfunction in both primary care and referral practice.

A review of hyperfibrinolysis in cats and dogs

The fibrinolytic system is activated concurrently with coagulation; it regulates haemostasis and prevents thrombosis by restricting clot formation to the area of vascular injury and dismantling the clot as healing occurs. Dysregulation of the fibrinolytic system, which results in hyperfibrinolysis, may manifest as clinically important haemorrhage. Hyperfibrinolysis occurs in cats and dogs secondary to a variety of congenital and acquired disorders. Acquired disorders associated with hyperfibrinolysis, such as trauma, cavitary effusions, liver disease and Angiostrongylus vasorum infection, are commonly encountered in primary care practice. In addition, delayed haemorrhage reported in greyhounds following trauma and routine surgical procedures has been attributed to a hyperfibrinolytic disorder, although this has yet to be characterised. The diagnosis of hyperfibrinolysis is challenging and, until recently, has relied on techniques that are not readily available outside referral hospitals. With the recent development of point-of-care viscoelastic techniques, assessment of fibrinolysis is now possible in referral practice. This will provide the opportunity to target haemorrhage due to hyperfibrinolysis with antifibrinolytic drugs and thereby reduce associated morbidity and mortality. The fibrinolytic system and the conditions associated with increased fibrinolytic activity in cats and dogs are the focus of this review article. In addition, laboratory and point-of-care techniques for assessing hyperfibrinolysis and antifibrinolytic treatment for patients with haemorrhage are reviewed.

Thromboelastography-guided transfusion in dogs with hypocoagulable disorders: a case series

BACKGROUND

Thromboelastography (TEG) is a global whole blood hemostasis assay which includes plasma as well as cellular components of hemostasis in the analysis and follows the quality and dynamics of clot development, stabilization, and lysis. In human medicine TEG is also a valuable asset in the therapeutic setting, allowing evaluation of the effect of transfusion therapy in vitro. This case series describes the use of TEG as a guiding tool for transfusion therapy in four dogs with hypocoagulable hemostatic disorders.

CASE PRESENTATION

Four dogs presented with hypocoagulable disorders of hemostasis, diagnosed as rodenticide intoxication, angiostrongylosis, disseminated intravascular coagulation following severe systemic inflammation, and immune-mediated thrombocytopenia, respectively. TEG was used as a diagnostic tool as well as a guiding tool in the decision of whether or not, and in what dose, fresh frozen plasma would be of benefit in the treatment protocol for each dog.

CONCLUSIONS

TEG may be applied in the therapeutic setting as a means to tailor individual patient transfusion therapy in critically ill dogs with hypocoagulable states.

Pulmonary arterial response to Angiostrongylus vasorum in naturally infected dogs: echocardiographic findings in two cases

Background

Angiostrongylus vasorum is a nematode living in the pulmonary arteries of canids. Infected dogs develop severe pulmonary lesions which can potentially lead to pulmonary hypertension (PH). However, reports of PH in natural infected dogs are scant. One of the possible causes of the low prevalence of PH in A. vasorum-infected dogs could be the establishment of large diameter intrapulmonary arteriovenous anastomoses (IPAVAs), which attenuate pulmonary vascular resistance, thus reducing the pulmonary arterial pressure. The present report describes the pulmonary arterial pressure (PAP) response to A. vasorum natural infection in two dogs, assessed by echocardiography and by the saline contrast echocardiographic test (SCE).

Results

Both dogs showed clinical signs of respiratory disease. At presentation, case 1 did not show echocardiographic signs of PH and the SCE test was positive proving the presence of IPAVAs. However, at the follow-up visit, despite A. vasorum infection resolution, the same dog showed PH and the SCE test resulted negative, which ruled out the presence of IPAVAs. Case 2 suffered from severe pulmonary arterial hypertension and right-side congestive heart failure since the day of presentation. Saline contrast echocardiography was negative both at the time of presentation and at the follow-up visit.

Conclusions

In the two cases described above, the PH was not associated with IPAVAs. During A. vasorum infection, IPAVAs recruitment mechanism is able to contrast the rise of PAP until a certain level. It probably represents an initial escape mechanism of PH that, over time, exhausts its compensatory capacities allowing PAP to rise and to be detectable on echocardiography.

Electronic supplementary material

The online version of this article (10.1186/s13071-019-3544-2) contains supplementary material, which is available to authorized users.

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.

Autochthonous Angiostrongylus vasorum in Finland

Angiostrongylus vasorum has spread farther north in Europe. In this study, two autochthonous findings from dogs from Finland are described: in February 2014, the infection was diagnosed in a 10-month-old labrador retriever, and in February 2017, in a three-year-old French bulldog. These diagnoses were based on direct detection of the larvae from faeces of the dogs. The dogs had no history of travel to or import from abroad; the first lived in Southern Finland and the other in Western Finland, about 150 km apart. The dogs had no clinical signs attributable to angiostrongylosis. An online questionnaire was used to survey the extent to which veterinarians in Finland have self-reportedly observed canine A vasorum infections. A total of 38 veterinarians authorised to work in Finland answered the questionnaire in December 2017, and 9 (24%) of them reported having seen one or more dogs with A vasorum infection in Finland. The results suggest that at least five individual dogs with A vasorum infection would have been seen in Finland, three of which had an apparently autochthonous infection. While the geographical distribution of A vasorum in Finland remains largely unknown, findings have started to appear from domestic dogs. It remains possible that some veterinarians could have misdiagnosed, for example, Crenosoma vulpis larvae as those of A vasorum, and the findings without confirmation using antigen test could be due to coprophagy and passage of ingested larvae; however, this does not change the main conclusion that can be made: A vasorum is already multifocally present in Finland. Increasing awareness about A vasorum is important in areas where it is emerging and spreading.

Determining resolution of Angiostrongylus vasorum in dogs following anthelmintic treatment with an imidacloprid 10 per cent/moxidectin 2.5 per cent spot-on

Objectives

To determine the time from treatment with a product containing imidacloprid 10 per cent/moxidectin 2.5 per cent spot-on (Advocate™), to dogs becoming negative for Angiostrongylus vasorum (A. vasorum). The authors hypothesised that most dogs would have resolution of A. vasorum within four weeks of treatment with Advocate™.

Design

Prospective, non-randomised, prepost treatment study.

Setting

Cases were enrolled from general practices along the southern coast of the United Kingdom.

Participants

Nine dogs completed the study and were enrolled if A. vasorum had been diagnosed based on a positive commercially available, in-clinic, serological A. vasorum antigen test (Angio Detect®) or Baermann performed at an external laboratory or both.

Interventions

The only treatment A. vasorum-positive dogs received was Advocate™ which was applied at the time of diagnosis and reapplied if necessary at four-weekly intervals until dogs tested negative by Angio Detect.

Primary outcome measures

Angio Detect® was performed and Advocate™ was reapplied at four-weekly intervals until dogs tested negative by this method.

Secondary outcome measures

Baermann was also performed at four-weekly intervals until dogs tested negative by this method.

Results

Application of Advocate™ was an effective treatment for A. vasorum infection in dogs and resulted in resolution of the infection, based on Angio Detect® testing and Baermann, within four weeks, in eight out of nine dogs. Post-treatment Angio Detect® testing was concordant with Baermann in seven of nine dogs.

Conclusions

Application of Advocate™ was an effective treatment for A. vasorum infection in dogs and resulted in resolution of the infection within four weeks in most dogs. Repeat Angio Detect® testing is recommended following treatment of A. vasorum to confirm resolution of the infection.

Hyperfibrinolysis and Hypofibrinogenemia Diagnosed With Rotational Thromboelastometry in Dogs Naturally Infected With Angiostrongylus vasorum

Background

The pathomechanism of Angiostrongylus vasorum infection‐associated bleeding diathesis in dogs is not fully understood.

Objective

To describe rotational thromboelastometry (ROTEM) parameters in dogs naturally infected with A. vasorum and to compare ROTEM parameters between infected dogs with and without clinical signs of bleeding.

Animals

A total of 21 dogs presented between 2013 and 2016.

Methods

Dogs with A. vasorum infection and ROTEM evaluation were retrospectively identified. Thrombocyte counts, ROTEM parameters, clinical signs of bleeding, therapy, and survival to discharge were retrospectively retrieved from patient records and compared between dogs with and without clinical signs of bleeding.

Results

Evaluation by ROTEM showed hyperfibrinolysis in 8 of 12 (67%; 95% CI, 40–86%) dogs with and 1 of 9 (11%; 95% CI, 2–44%) dogs without clinical signs of bleeding (P = .016). Hyperfibrinolysis was associated with severe hypofibrinogenemia in 6 of 10 (60%; 95% CI, 31–83%) of the cases. Hyperfibrinolysis decreased or resolved after treatment with 10–80 mg/kg tranexamic acid. Fresh frozen plasma (range, 14–60 mL/kg) normalized follow‐up fibrinogen function ROTEM (FIBTEM) maximal clot firmness in 6 of 8 dogs (75%; 95% CI, 41–93%). Survival to discharge was 67% (14/21 dogs; 95% CI, 46–83%) and was not different between dogs with and without clinical signs of bleeding (P = .379).

Conclusion and Clinical Importance

Hyperfibrinolysis and hypofibrinogenemia were identified as an important pathomechanism in angiostrongylosis‐associated bleeding in dogs. Hyperfibrinolysis and hypofibrinogenemia were normalized by treatment with tranexamic acid and plasma transfusions, respectively.

[Acquired von-Willebrand factor and factor-VIII deficiencies caused by angiostrongylosis in a dog]

An 8-year-old male Australian Shepherd was presented with bleeding from the lip and hemoabdomen. Hematology demonstrated marked thrombocytopenia and anemia. Abdominal ultrasound followed by laparotomy did not detect the cause of bleeding. Plasma transfusion resulted in temporary stabilization. Severe von-Willebrand factor deficiency and factor-VIII deficiency were diagnosed. After subsequent bleeding episodes, infection with Angiostrongylus vasorum was found in both a fecal parasitological examination and by PCR from EDTA-blood. Following successful therapy with fenbendazole, von Willebrand factor and factor VIII were within the normal range. This is the second case report of an acquired von-Willebrand-factor deficiency associated with Angiostrongylus-vasorum infection in a dog, and the first case report with concurrent factor-VIII deficiency.