Clinical, laboratory and pathological findings in cats experimentally infected with Aelurostrongylus abstrusus

Abstract

Aelurostrongylus abstrusus parasitizes the respiratory tract and can heavily affect the breathing and general condition of cats. Experimental infections of six cats were initiated by intragastric administration with 100 or 800 third-stage larvae (L3) obtained from the terrestrial snail Helix aspersa. First-stage larvae were isolated from faecal samples after 35-41 days post infection (dpi) in five animals and until end of study (84 dpi) in two cats. Cough and respiratory sounds were observed starting from 28 to 41 dpi and dyspnoea and panting starting from 52 dpi. All cats had enlarged lymph nodes and, starting from 56 dpi, reduced body weight, and four cats showed intermittent reduced general condition with apathia and anorexia. Eosinophilia and leucocytosis partially with massive lymphocytosis, and occasional basophilia and monocytosis were observed. Mild anaemia was present in five cats, while alterations in coagulation parameters suggested stimulation of the coagulation cascade with increased consumption of coagulation factors (delayed PT, hypofibrinogenemia). Adult A. abstrusus specimens were isolated from the five patent cats at necropsy and all six cats showed pathological changes in the lungs, including disseminated inflammatory cell infiltrates, often associated with incorporated larvae and eggs. There was some degree of overlap between the severity and the inoculation doses. Infections starting from 100 L3 of A. abstrusus had an impact on the lung tissues and on the health of the cats, despite the presence of only mild haematological abnormalities. Due to the worldwide occurrence of feline lung worms, parasitic infections should be considered in the differential diagnosis of lung diseases regardless of the presence of clinical signs and larval excretion.

Larval development of the cat lungworm Aelurostrongylus abstrusus in the tropical freshwater snail Biomphalaria glabrata

“…Infected cats mostly show respiratory signs (Grandi et al 2005;Traversa et al 2008), but nonpathognomic signs (Genchi et al 2014;Schnyder et al 2014) or asymptomatic cats are also commonly observed (Genchi et al 2014). In some cases, an infection with A. abstrusus may result in death (Gerdin et al 2011;Dirven et al 2012;Philbey et al 2014).…”

Efficacy of Emodepside/Praziquantel Spot-on (Profender®) against adult Aelurostrongylus abstrusus Nematodes in Experimentally Infected Cats

“…As these guidelines do not include specific information on A. abstrusus, the study design was based on scientific knowledge and experience gained in a preliminary study (Schnyder et al 2014). The study designs are summarised in Table 1.…”

“…In general, these guidelines consider a minimum of 6 animals in the control group with at least 5 worms each to be adequate. However, as the guidelines do not include specific recommendations for studies with A. abstrusus and lower infection rates were observed in a preliminary study (Schnyder et al 2014), an infection with at least one worm in each of 6 control animals was deemed to be adequate. Additionally, the lower limit of the 95 % confidence interval was required to be greater than 10 % of the geometric mean.…”

“…Depending on the worm burden, age and immune response of the infected animal, the clinical presentation varies from asymptomatic to fatal. Symptoms include respiratory signs such as dyspnoea, coughing, sneezing and nasal discharge and unspecific signs such as lethargy, depression and weight loss (Hamilton 1967, Scott 1973, Schnyder et al 2014. Aelurostrongylus abstrusus has a worldwide distribution and, although the infection is considered sporadic in many countries, prevalences can reach around 20 % in endemic areas, e.g.…”

Aelurostrongylus abstrusus - the cause of respiratory disease

“…The infection is usually asymptomatic. However, in the case of an intensive infection of the respiratory system, symptoms such as a chronic cough, dyspnea, nasal discharge, accelerated breathing, loss of appetite and sometimes diarrhoea and anorexia may be observed (4,18,23). The laboratory diagnosis during the prepatent period also presents difficulties due to the lack of diagnostic tests.…”