Prevalence and clinico-diagnostic evaluation of mixed gastrointestinal parasitic infections in dogs

Introduction

Gastrointestinal (GI) parasitic infections are among the important health problems affecting dogs and may adversely influence their health and productivity. Dogs can harbour a variety of gastrointestinal parasites, some of which are of zoonotic importance, thereby posing a potential public health concern (Souza et al., 2023; Wani et al., 2017; Mathew et al., 2016) [23,24] . The occurrence and severity of parasitic infections may vary depending on several factors, including age, breed, management practices, environmental conditions and exposure to infective stages of parasites. (Ferreira et al., 2016; Wani et al., 2017) [9,24] Gastrointestinal parasitic infections may produce a wide range of clinical manifestations in dogs, including anorexia, diarrhoea, vomiting, weakness, weight loss, anaemia, abdominal distension and poor coat condition. The severity of clinical manifestations depends on the parasite species, intensity of infection and the general health status of the animal. Mixed infections involving two or more gastrointestinal parasites may result in overlapping clinical manifestations and may complicate their diagnosis and clinical management. (Matthew et al., 2016) [13] . Several gastrointestinal parasites of dogs, including Ancylostoma caninum, Toxocara canis, Toxascaris leonina www.extensionjournal.com and Dipylidium caninum, are commonly encountered, and some have zoonotic significance. Toxocara canis is associated with visceral and ocular larva migrans in humans (Dogan et al., 2007) [7] , while hookworm infections may cause cutaneous larva migrans and other zoonotic manifestations. Therefore, accurate detection and appropriate identification of gastrointestinal parasites in dogs are important from both veterinary and public health perspectives. (Souza et al., 2023) [23] Copro-parasitological examination remains an important approach for the diagnosis of gastrointestinal parasitic infections. Different techniques, including direct faecal smear, sedimentation and flotation methods, may vary in their ability to detect parasitic stages. Evaluation of haematological and serum biochemical alterations may additionally provide useful information regarding the systemic effects associated with gastrointestinal parasitism. (Qadir et al., 2011; Shahat et al., 2022; Payghan et al., 2023) [17, 20, 15] . Although gastrointestinal parasitic infections in dogs have been widely reported, information specifically concerning mixed gastrointestinal parasitic infections, their prevalence, clinical manifestations, diagnostic findings and associated haemato-biochemical alterations is comparatively limited in the study region. Therefore, the present study was undertaken to determine the prevalence of mixed gastrointestinal parasitic infections in dogs and to evaluate their clinical manifestations, copro-parasitological diagnostic findings and associated haemato-biochemical alterations.

Materials and methods

Study Area and Study Population

The study was conducted at the Veterinary Clinical Complex, College of Veterinary Science, Proddatur. A total of 604 dogs presented to the clinical complex were screened for gastrointestinal parasitic infections based on clinical examination and relevant clinical history.

Faecal

Sample Collection and Parasitological Examination Fresh faecal samples were collected from the dogs in clean, labelled containers and subjected to copro-parasitological examination. Three diagnostic techniques, namely direct faecal smear, sedimentation and zinc sulphate flotation, were employed for detection and identification of gastrointestinal parasitic ova and other parasitic stages. Identification was carried out based on the morphological characteristics of the parasitic eggs as described by Soulsby (1982) [22] . Of the 604 dogs screened, 314 were positive for gastrointestinal parasitic infections. Among these positive dogs, 293 had single parasitic infections, and 21 had mixed gastrointestinal parasitic infections. The 21 dogs with mixed infections constituted the study group for evaluation of their clinical, diagnostic and haemato-biochemical findings.

Clinical Examination

Detailed clinical examination was performed in dogs diagnosed with mixed gastrointestinal parasitic infections. Clinical findings including anorexia, diarrhoea, vomiting, weakness, pale mucous membranes, poor coat condition, emaciation, abdominal bloating, pyrexia, lethargy and congested mucous membranes were recorded.

Haematological and Serum Biochemical Examination

Blood samples were collected from the affected dogs for haematological and serum biochemical evaluation. Haematological parameters included haemoglobin, total erythrocyte count, total leucocyte count, packed cell volume, differential leucocyte count and platelet count. Serum biochemical parameters evaluated included alanine aminotransferase, aspartate aminotransferase, alkaline phosphatase, blood urea nitrogen, creatinine, total bilirubin, total protein and albumin. The obtained results were evaluated and interpreted based on the standard reference values reported by Jain (1993) [11] .

Statistical Analysis

The data were analysed using SPSS software. The association of breed, age and gender with the occurrence of mixed gastrointestinal parasitic infection was evaluated using the chi-square test. Haematological and serum biochemical parameters of healthy and mixed gastrointestinal parasiticinfected dogs were compared using a two-sample t-test. A probability value of P<0.05 was considered statistically significant.

Results

Prevalence and Pattern of Mixed Gastrointestinal Parasitic Infections

A total of 604 dogs were screened for gastrointestinal parasitic infections during the study period. Of these, 314 dogs (51.98%) were found to be positive for gastrointestinal parasitic infections. Among the 314 positive dogs, 293 had single gastrointestinal parasitic infections, whereas 21 had mixed gastrointestinal parasitic infections. Thus, mixed gastrointestinal parasitic infections were recorded in 21/604 dogs, giving an overall prevalence of 3.48% in the screened population. Mixed infections constituted 21/314 (6.69%) of the gastrointestinal parasite-positive dogs. Among the 21 dogs with mixed gastrointestinal parasitic infections, Ancylostoma caninum + Toxocara canis was the most frequently detected combination, occurring in 9/21 dogs (42.86%). This was followed by Ancylostoma caninum + Dipylidium caninum in 7/21 dogs (33.33%) and Toxocara canis + Toxascaris leonina in 5/21 dogs (23.81%). The distribution of mixed gastrointestinal parasitic infections is presented in Table 1 and representative photomicrographs of gastrointestinal parasitic ova identified during faecal examination are shown in Plate 1.

Association of Mixed Gastrointestinal Parasitic Infection with Breed, Age and Gender

The occurrence of mixed gastrointestinal parasitic infection was evaluated in relation to breed, age and gender. Among the 21 dogs with mixed infections, mongrel dogs showed the highest occurrence (6/21; 28.57%), followed by Labrador (4/21; 19.04%), Pomeranian (3/21; 14.28%), German Shepherd (3/21; 14.28%), Golden Retriever (2/21; 9.52%), Dachshund (2/21; 9.52%) and Shih Tzu (1/21; 4.76%). However, no statistically significant association was observed between breed and occurrence of mixed gastrointestinal parasitic infection (χ² = 5.33; P = 0.50) as shown in Table 2. Age showed a highly significant association with the occurrence of mixed gastrointestinal parasitic infection (χ² = www.extensionjournal.com 14.24; P = 0.0026). The highest proportion of mixed infections was recorded in dogs aged 0-6 months (12/21; 57.14%), followed by 7-12 months (6/21; 28.57%), 13-36 months (2/21; 9.52%) and 37-60 months (1/21; 4.76%) as given in Table 3. Regarding gender, mixed gastrointestinal parasitic infection was recorded in 11/21 male dogs (52.38%) and 10/21 female dogs (47.62%). The association between gender and occurrence of mixed infection was not statistically significant (χ² = 0.0476; P = 0.83) as indicated in Table 4.

Copro-parasitological

Diagnosis of Mixed Gastrointestinal Parasitic Infections Three copro-parasitological techniques, namely direct faecal smear, sedimentation and zinc sulphate flotation, were employed for the detection of mixed gastrointestinal parasitic infections in the 21 affected dogs. Zinc sulphate flotation detected mixed infections in 9/21 dogs (42.86%), followed by sedimentation in 8/21 dogs (38.09%) and direct faecal smear in 4/21 dogs (19.05%). Zinc sulphate flotation showed the highest detection rate among the three techniques. However, the difference in detection among the diagnostic methods was not statistically significant (χ² = 2.024; P = 0.3635) as summarized in Table 5.

Clinical Manifestations

The major clinical manifestations observed in dogs with mixed gastrointestinal parasitic infections were anorexia ( 6. Anorexia and weakness were the most frequently recorded clinical manifestations, followed by diarrhoea and vomiting. The occurrence of these clinical manifestations may be associated with the gastrointestinal effects and systemic consequences of parasitic infection.

Haematological Alterations

Haematological parameters were evaluated in 21 dogs with mixed gastrointestinal parasitic infections and compared with those of 12 healthy dogs as detailed in Table 7 The mean haemoglobin, total erythrocyte count and packed cell volume values were significantly reduced in infected dogs compared with healthy dogs (P≤0.01). A highly significant reduction in lymphocyte count was also observed in infected dogs. In contrast, total leucocyte count, neutrophil count and eosinophil count were significantly increased (P<0.01), indicating leucocytosis, neutrophilia and eosinophilia, respectively. No statistically significant differences were observed in monocyte and platelet counts (P>0.05). The observed reduction in haemoglobin, erythrocyte count and packed cell volume indicates anaemia associated with mixed gastrointestinal parasitic infection, whereas the increases in leucocyte, neutrophil and eosinophil counts reflect the haematological response associated with parasitic infection.

Serum Biochemical Alterations

Serum biochemical parameters were evaluated in 21 dogs with mixed gastrointestinal parasitic infections and compared with those of 12 healthy dogs as depicted in Table 8. The mean serum alanine aminotransferase (ALT), aspartate aminotransferase (AST) and alkaline phosphatase (ALP) activities were significantly higher in infected dogs than in healthy dogs (P<0.01). Mean blood urea nitrogen (BUN) concentration was significantly lower in infected dogs (P<0.05). Total protein and albumin concentrations were also significantly reduced in infected dogs compared with healthy dogs (P<0.01). No statistically significant differences were observed in serum creatinine or total bilirubin concentrations between healthy and infected dogs (P>0.05). The observed increases in ALT, AST and ALP, together with reductions in total protein and albumin, indicate alterations in serum biochemical parameters associated with mixed gastrointestinal parasitic infection.

Discussion

Mixed gastrointestinal parasitic infections are of clinical and epidemiological importance in dogs because simultaneous infection with more than one parasite may result from exposure to multiple sources of infection. In the present study, 21 of 604 dogs screened were affected with mixed gastrointestinal parasitic infections, corresponding to an overall prevalence of 3.48%. Among the 314 gastrointestinal parasite-positive dogs, mixed infections accounted for 6.69% (21/314). The prevalence observed in the present study was comparable with the prevalence reported by Souza et al. (2023) [23] , whereas higher prevalences were reported by Ahmed et al. (2018) and Wani et al. (2017) [24] . Variation among studies may be associated with differences in geographical location, management practices, environmental conditions, host population and diagnostic methods. Among the mixed infections identified in the present study, Ancylostoma caninum + Toxocara canis was the most frequently detected combination, followed by Ancylostoma caninum + Dipylidium caninum and Toxocara canis + Toxascaris leonina. The occurrence of these combinations may reflect simultaneous exposure of dogs to different infective stages present in the environment. Breed was not significantly associated with the occurrence of mixed gastrointestinal parasitic infections (P>0.05). Although mongrel dogs represented the largest proportion of affected animals, this difference was not statistically significant. These findings are similar to those of Dubie et al. (2023) [8] . Breed-related variation in parasitic infection may be influenced by management practices, housing, nutrition, veterinary care and roaming or scavenging behaviour. A highly significant association was observed between age and occurrence of mixed gastrointestinal parasitic infection (χ² = 14.24; P = 0.0026). The highest proportion of mixed infections was recorded in dogs aged 0-6 months, followed by those aged 7-12 months. The higher occurrence among younger dogs may be associated with their comparatively immature immune response and, in some parasitic infections, transplacental or transmammary transmission of infective larvae. (Bowman, 2009 and Ambily et al., 2011) [5,2] Similar age-related susceptibility has been reported by Ferreira et al. (2016) [9] and Matthew et al. (2016), while differences among www.extensionjournal.com studies may reflect variations in study population and environmental exposure. Gender was not significantly associated with mixed gastrointestinal parasitic infection (P>0.05). Male dogs accounted for 11/21 (52.38%) cases, whereas female dogs accounted for 10/21 (47.62%). Similar findings were reported by Nguyen et al. (2022) [14] and Souza et al. (2023) [23] , although some studies have reported higher infection rates in males. Such variations may be influenced by differences in behaviour, management, hormonal status and environmental exposure. Among the copro-parasitological techniques evaluated, zinc sulphate flotation showed the highest detection rate (9/21; 42.86%), followed by sedimentation (8/21; 38.09%) and direct faecal smear (4/21; 19.05%). However, the difference among the three diagnostic techniques was not statistically significant (χ² = 2.024; P = 0.3635). The higher detection observed with zinc sulphate flotation may be related to its ability to concentrate parasitic stages and facilitate their microscopic detection. Similar observations regarding the usefulness of flotation techniques have been reported by Rodriguez et al. (2023) [18] . The major clinical manifestations recorded in affected dogs were anorexia, weakness, diarrhoea, vomiting and pale mucous membranes, followed by poor coat condition, emaciation, abdominal bloating, pyrexia, lethargy and congested mucous membranes. These findings were comparable with those reported by Kumar et al. (2014) [12] , Pradeep (2016) [16] , Campos et al. (2017) [6] and Gayatri and Soya (2018). The clinical manifestations may vary according to the parasite species, intensity of infection and the general health status of the affected animal. The haematological findings demonstrated significant reductions in haemoglobin, total erythrocyte count and packed cell volume in infected dogs compared with healthy dogs, consistent with the findings of Qadir et al. (2011) [17] , Kumar et al. (2014) [12] , Baba et al. (2017) [4] , Shahat et al. (2022) [20] and Payghan et al. (2023) [15] . The reduction in erythrocytic parameters may be associated with blood loss, nutritional deficiencies and the effects of gastrointestinal parasites (Smith et al., 2005; Da Silva et al., 2015). A significant decrease in lymphocyte count was observed, in agreement with Qadir et al. (2011) [17] and Baba et al. (2017) [4] , whereas Kumar et al. (2014) [12] and Shahat et al. (2022) [20] reported no significant alteration. Total leucocyte, neutrophil and eosinophil counts were significantly increased, with similar findings reported by Kumar et al. (2014) [12] , Shahat et al. (2022) [20] and Audu et al. (2024) [3] for leucocytosis, Audu et al. (2024) [3] for neutrophilia, and Qadir et al. (2011) [17] , Kumar et al. (2014) [12] , Baba et al. (2017) [4] , Shahat et al. (2022) [20] , Audu et al. (2024) [3] and Payghan et al. (2023) [15] for eosinophilia. These changes may reflect inflammatory and host immune responses to parasitic infection. No significant differences were observed in monocyte and platelet counts, consistent with Qadir et al. (2011) [17] , Kumar et al. (2014) [12] , Baba et al. (2017) [4] , Shahat et al. (2022) [20] and Payghan et al. (2023) [15] . Serum biochemical analysis showed significantly increased ALT, AST and ALP activities, along with significant reductions in BUN, total protein and albumin in infected dogs. These findings were comparable with the observations of Kumar et al. (2014) [12] , Shahat et al. (2022) [20] , Saichenko et al. (2022) [19] , Campos et al. (2017) [6] and Payghan et al. (2023) [15] . The increased hepatic enzyme activities may reflect hepatic alterations associated with parasitic infection, whereas reduced protein and albumin concentrations could be related to intestinal protein loss, poor nutrient absorption and reduced feed intake (Kumar et al., 2014; Campos et al., 2017) [12, 6] . Creatinine remained comparable between groups, consistent with Baba et al. (2017) [4] and Saichenko et al. (2022) [19] , while total bilirubin showed no significant variation, contrary to the findings of Saichenko et al. (2022) [19] . Overall, the observed biochemical changes suggest systemic effects of gastrointestinal parasitism involving hepatic function and protein metabolism.

Conclusion

Mixed gastrointestinal parasitic infections were recorded in 21/604 dogs screened, with an overall prevalence of 3.48%, and accounted for 6.69% of the gastrointestinal parasitepositive dogs. Ancylostoma caninum + Toxocara canis was the most frequently observed mixed infection. Age showed a highly significant association with the occurrence of mixed gastrointestinal parasitic infection, whereas breed and gender were not significantly associated. Zinc sulphate flotation showed the highest detection rate among the coproparasitological techniques evaluated, although the difference among diagnostic methods was not statistically significant. Mixed gastrointestinal parasitic infections were associated with significant haematological and serum biochemical alterations, including anaemia-associated changes, leucocytosis, neutrophilia, eosinophilia, increased hepatic enzyme activities and reductions in total protein and albumin. The findings emphasize the importance of routine coproparasitological examination and appropriate diagnostic evaluation for the detection and management of mixed gastrointestinal parasitic infections in dogs.

References

1. Ahmad PA, Sharma R, Katoch R, Yadav A, Godara R, Rafiqui SI. Incidence of gastrointestinal helminths of stray dogs: a post mortem study. Haryana Vet. 2018;57(2):222-223.
2. Ambily VR, Pillai UN, Arun R, Pramod S, Jayakumar KM. Detection of human filarial parasite Brugia malayi in dogs by histochemical staining and molecular technique. Vet Parasitol. 2011;181(2-4):210-214.
3. Audu Y, Yusuf. Prevalence of Gastrointestinal Nematodes of Dogs and Associated Hematological Changes in Gombe State, Nigeria. Research Square. 2024. doi:10.21203/rs.3.rs-4852349/v1.
4. Baba A, Khuranna K, Dar S, Shah O, Rather M, Khaliq T. Prevalence and haemato-biochemical alterations in GI helminthes infected dogs from Bareilly, India. Int J Livestock Res. 2017;7(7):166-171.
5. Bowman DD. Georgi's Parasitology for Veterinarians. 9th ed. Saunders Company; 2009:182-183.
6. Campos DR, Perin LR, Camatta NC, Oliveira LC, Siqueira DF, Aptekmann KP, et al. Canine hookworm: correlation between hematological disorders and serum proteins with coproparasitological results. Braz J Vet Med. 2017;39(3):147-151.
7. Dogan N, Dinleyici EC, Bor O, Toz SO, Ozbel Y. Sero epidemiological survey for Toxocara canis infection in the northwestern part of Turkey. Turkiye Parazitol Derg. 2007;31(4):288-291.
8. Dubie T, Sire S, Fentahun G, Bizuayehu F. Prevalence of gastrointestinal helminths of dogs and associated factors in Hawassa city of Sidama region, Ethiopia. J Parasitol Res. 2023;2023:6155741.
9. Ferreira JIGDS, Pena HFJ, Azevedo SS, Labruna MB, Gennari SM. Occurrences of gastrointestinal parasites in fecal samples from domestic dogs in Sao Paulo, SP, Brazil. Rev Bras Parasitol Vet. 2016;25(4):435-440.
10. Gayathri S, Soya K. An epidemiological study of gastrointestinal parasitism in tamed dogs and its zoonotic prevalence in the society of Southern Kerala. Indian J Sci Res. 2018;19(2):17-20.
11. Jain NC. Examination of blood and bone marrow. In: Essentials of Veterinary Haematology. Lea and Febiger; 1993:185-207.
12. Kumar M, Sharma B, Kumar A, Lal HP, Kumar V, Tripathi MK. Prevalence and haemato-biochemical studies of Toxocara canis infestation in dogs and risk perception of zoonoses by dog owners in Mathura, India. Asian J Anim Vet Adv. 2014;9(10):653-663.
13. Matthew TT, Seer IJ, David OK. The prevalence of gastrointestinal helminths (GIH) infection of dogs in Makurdi metropolis. Imperial J Interdiscip Res. 2016;2(8):1042-1049.
14. Nguyen TTM, Dorny P, Dinh TD, Nguyen VT, Nguyen HN, Nguyen TGT, Dermauw V. Helminth infections in dogs in Phu Tho Province, northern Vietnam. Curr Res Parasitol Vector Borne Dis. 2022;2:100091.
15. Payghan PS, Bhojne GR, Dhoot VM, Panchbhai CG, Kolte SW, Tembhurne PA, Shrideeksha. Therapeutic management and haemato-biochemical alterations in diarrhoeic dogs affected with ancylostomosis. Pharma Innov J. 2023;12(5):4669-4672.
16. P.V. Narsimha Rao Telangana Veterinary University; 2016.
17. Qadir S, Dixit AK, Dixit P, Sharma RL. Intestinal helminths induce haematological changes in dogs from Jabalpur, India. J Helminthol. 2011;85(4):401-403.
18. Rodriguez JY, Cummings KJ, Hodo CL, Hamer SA. A repeated cross-sectional study of intestinal parasites in Texas shelter dogs using fecal flotation and saline sedimentation. Parasitol Res. 2023;122(1):237-243.
19. Saichenko I, Antipov A, Bakhur T, Bezditko L. Deworming schemes' efficacy for adult dogs with mixed gastro-intestinal helminthoses. Folia Vet. 2022;66(1):15-25.
20. Shahat MS, Abdel RA, Abdel R, Adel EAM. Hematobiochemical changes in dogs infected with Toxocara canis in Hurghada and Luxor governorate. South Valley Univ Int J Vet Sci. 2022;5(1):56-67.
21. Smith VH, Jones TP, Smith MS. Host nutrition and infectious disease: an ecological view. Front Ecol Environ. 2005;3(5):268-274.
22. Soulsby EJL. Helminths, Arthropods and Protozoa of Domesticated Animals. 7th ed. Baillière Tindall; 1982.
23. Souza CTVD, Dorr AP, Silva VLDB, Silva FDL, Silva EBD, Ramos DGS, Pacheco RC, Sousa VRF. Occurrence of gastrointestinal parasites in dogs from Cuiabá, Mato Grosso. Rev Bras Parasitol Vet. 2023;32(1):e012322.
24. Wani Z, Allaie I, Shahardar RA, Maqbool I, Gazi M. Gastrointestinal parasitism in stray dogs at Srinagar city of Kashmir Valley. Indian Vet J. 2017;94(8):18-20.