Hematological and Biochemical Changes in Dogs Naturally Infected With Dirofilaria repens

Abstract

Subcutaneous dirofilariosis is a zoonotic disease emerging throughout Europe caused by the filarial nematode Dirofilaria repens . Despite its increasing prevalence, there is a large gap in knowledge of the impact of the parasite on the host. Currently classified as being non-pathogenic, recent evidence suggests that skin dirofilariosis is associated with dermatological conditions including concomitant pruritus, neoplastic processes, inflammation, and even blindness in dogs and humans. The aim of this study was to determine if natural canine D. repens infection leads to biological changes in the canine host. In a real-life veterinary clinic setting, animals are often presented to clinicians for unrelated issues, and D. repens is incidentally identified during inspection. As such, we compared hematological and biochemical parameters of 218 uninfected and 197 dogs naturally infected with D. repens . Interestingly, animals infected with D. repens had lower numbers of lymphocytes ( p < 0.001), red blood cells ( p < 0.001), and thrombocytes ( p = 0.025), decreased hematocrit ( p < 0.001), and increased alkaline phosphatase ( p = 0.016) and creatinine activity ( p = 0.023) compared to uninfected dogs. We further selected a subpopulation of 214 dogs having prima facie hematological and biochemical results within normal reference ranges to evaluate the effect of D. repens infections in seemingly healthy dogs. Among these patients, 93 dogs infected with D. repens had lower numbers of lymphocytes ( p = 0.031), red blood cells ( p = 0.025), and hematocrit ( p = 0.002), higher glucose levels ( p = 0.023), and border line elevated alkaline phosphatase levels ( p = 0.054) compared to 121 uninfected animals. Despite being categorized as asymptomatic, we have observed hematological and biochemical changes associated with D. repens infections in dogs, and our data suggest that dirofilariosis may induce a state of chronic stress. These results link the presence of skin dirofilariosis to biological changes in the canine host, suggesting a mechanism for pathogenicity and shedding new light on the host–parasite relationship.

Case Studies of Severe Microfilaremia in Four Dogs Naturally Infected With Dirofilaria repens as the Primary Disease or a Disease Complicating Factor

“…The goal of this article was to report the details of four cases of high D. repens microfilaremia. Hematological and biochemical findings in dogs infected with Dirofilaria repens included anemia, thrombocytopenia, leucocytosis, neutrophilia, eosinophilia, monocytosis and increased values of alkaline phosphatase, aspartate transaminase, alanine aminotransferase, blood urea nitrogen, creatinine, bilirubin as well as hypoalbuminemia, which is in keeping with results described by other authors (28,29).…”

“…Helminths are known to suppress the host immune response in order to establish infection. For instance, it has been recently reported that D. repens may influence the host immune response by inducing a state of chronic in the canine host (29). It is possible that patients with high Mf counts may represent a population with pre-existing immunosuppression and are unable to naturally control or respond to the parasites.…”

Emergence of zoonotic filariasis,&nbsp;Dirofilaria repens, in eastern Thailand 2019-2020:&nbsp;The&nbsp;impact of climate change

“…But recently, some studied suggested that subcutaneous diro lariasis is related with dermatological symptoms together with concomitant pruritus, neoplastic processes, in ammation and blindness in dogs and humans. The blood parameters in dogs were changed during infection along with deceasing of white blood cell, red blood cell and platelet and increasing of alkaline phosphatase and creatinine activity (Wysmolek et al, 2020).…”

Emergence of Dirofilaria repens (Spirurida: Onchocercidae) in dogs in Eastern Thailand

“…Dirofilariasis caused by D. repens is considered as a nonpathogenic disease. However, recent research has suggested that subcutaneous dirofilariasis is associated with dermatological symptoms together with concomitant pruritus, neoplastic processes, inflammation, and blindness in dogs and humans [19].…”

“…It was observed that the blood parameters in dogs were altered during infection, with a reduction in the number of white blood cells, red blood cells, and platelets and an increase in alkaline phosphatase and creatinine activities [19].…”