Introduction

Parasitism is the most encountered disease in dogs all over the world. Dogs may be infected with parasites that are dangerous to man and domestic animals Zelon (2003). Among various parasitic diseases, gastro-intestinal (GI) helminths have been identified as the major impediment to dog health worldwide owing to the direct and indirect losses they cause Smith (1991). Parasitized animals show a variety of symptoms, depending on the parasite species and parasitic load. These signs include intestinal obstruction, irritation, maldigestion, malabsorbtion, and protein losing gastroentropathy induced by the parasites Dunn (1978). Regardless of the availability of effective medications to treat parasitic diseases, most parasites of dogs have evolved their life cycles to make their elimination impossible. Further, impact of intestinal helminth infection on the haemogram of infected dogs has appeared in the literature Mittra and Sasmal (1984). Toxocara canis and Ancylostoma caninum are the highly encountered parasitic species in dogs because of their high fecundity rate and more than one route of infection to the host. The present study was carried out to generate the data on prevalence of GI parasitic infection in naturally infected dogs and their effect on haematological and biochemical parameters.

Materials and Methods

The study was carried out at Indian Veterinary Research Institute (IVRI), Izatnagar, Bareilly, Uttar Pradesh, India, located 28.10^° N, 78.23^° E in the northern region of India at an average altitude of 240m ASL during year 2001 -2012. Fecal samples were collected from 434 dogs (253 males and 181 females) attending the Referral Veterinary Polyclinic, IVRI for routine examination between September and March. Dogs aged less than 6 months were classified as young (n=88) and those above 7 months were taken to be adults (n=346). Fecal samples were collected from dogs for routine examination by direct smear method and negative samples were subjected to further examination by concentration methods viz. sedimentation and floatation methods. The eggs were identified by morphology and morphometry Soulsby (1986). Based on the presence or absence of parasitic infections, the dogs were divided into parasitized (n=190) and non-parasitized (n=244) groups.

For haematological examination, blood was collected from the cephalic vein of each dog. Each blood sample was divided into a pair. One sample was kept in a clean sterile vial containing ethylene diamine tetra-acetic acid (EDTA) as anticoagulant for estimation of haemoglobin (Hb), packed cell volume (PCV) and total erythrocyte count (TEC), total leucocyte counts (TLC) and differential leucocyte counts (DLC) by standard protocols. Another blood sample was kept as such for extraction of serum for the biochemical analysis including serum creatinine, blood urea nitrogen (BUN), alanine transaminase (ALT) and alkaline phosphatase (ALKP) which was carried out with ready to use kits using automatic analyser (IDEXX labs.).

Data Analysis

Haematological and biochemical data was analysed statistically using Wilcoxon–Mann–Whitney test.

Results and Discussion

Out of the 434 dogs coprologically examined, 190 (43.77%) were found to be positive for GI helminths and harboured one or more intestinal helminth parasites. The overall infection rate (43.77%) recorded in the present study is almost similar to the findings of Kutdang et al. (2010) from Nigeria, who recorded the prevalence of gastro-intestinal parasites as 41.69%. Ancylostoma caninum and Toxascaris canis were found in 90 and 64 samples, respectively, with a prevalence rate of 20.74% and 14.74%, respectively. 36 samples were found positive for both T. canis and A. caninum i.e., mixed infection. The intensity of A. caninum infection was highest, with mean egg counts of 965.56 ±105.75, followed by Toxocara canis (324.74±79.34). Similar prevalence rate of Ancylostoma caninum was reported in Ethiopia (22%) by Yacob et al. (2007) and in Ludhiana, Punjab (22.41%) by Singh et al. (2012). However, much lower prevalence rates were reported by Miró et al. (2007) from Spain (4%); whereas much higher were reported by Wang et al. (2006) from China (66.3%). Using a combination of PCR and conventional microscopy, Traub et al. (2004) reported a prevalence of 36% of A. caninum in the endemic tea growing communities of Assam, India. This variation in the prevalence rates in different parts of the world may be due to various factors such as geographical location, status of animal ownership, sampling protocols, demographic factors, anthelmintic usage¸ diagnostic techniques employed and also differences in management systems viz. health care facilities, degree of environmental contamination with infective stages and exposure to natural infection.

Prevalence of A. caninum, T. canis and mixed infection (A. caninum + T. canis) was 26.88%, 18.58% and 6.32% in males and 12.15%, 9.39% and 11.05% in females, respectively. A. caninumhad significantly (P<0.05) higher prevalence rates in male as compared to female dogs. Prevalence of A. caninum, T. canis and mixed infection (A. caninum + T. canis) was 26.13%, 29.54% and 13.64% in pups and 19.36%, 10.98% and 6.94% in adult dogs, respectively. T. canishad significantly (P<0.05) higher prevalence rates in pups as compared to adult dogs. The study recorded higher prevalence of A. caninum in males as compared to female dogs and also a higher prevalence of T. canis in pups as compared to adults dogs. Previous studies reported no difference in the prevalence rates of T. canis between the two sexes (Singh et al., 2012). Higher prevalence rates were recorded during winter months from December to March with highest prevalence rate during March (55.37%) and lowest was recorded in November (38.46%) (Fig.1).

Fig. 1: Month wise prevalence of gastro-intestinal helminths in dogs

The trend of the present results on seasonal prevalence is also supportive of the observations recorded by Sharma et al. (2006). The specific use of anti-hookworm drugs in pregnant bitches and prophylactic therapy in pups may have further reduced the prevalence rate of the parasite in Bareilly, India.

Haematological data from parasitized and non-parasitized dogs are summarized in Table 1. The levels of erythrocytic parameters (Hb, PCV and TEC) were significantly lower (P<0.01) in the parasitized than in the non-parasitized group of animals, whereas group differences for TLC, neutrophils, monocytes and basophils were non-significant. A significant increase (P<0.01) in eosinophils and decrease in lymphocytes was also recorded in parasitized compared to non-parasitized animals. These findings strengthen the earlier claims that the parasite under investigation, is a voracious blood sucker and leads to anemia (Mittra and Sasmal, 1984). Eosinophilia observed in the helminth infected dogs may be the result of constant irritation caused by the bites of parasite on intestinal mucosa causing damage and inflammation along the way (Leder and Weller, 2000). Eosinophils are potent effector cells associated with the killing of helminths, as evidenced from their close association with damaged or dead parasites in histological sections and positive correlation with acquired resistance by the parasitized host (Kirkova et al., 2005). These observations are also in accordance to the established fact that GI parasitism is characterized by absolute eosinophilia.

Table 1: Haematological parameters in parasitized and non-parasitized dogs (Mean ± SE)

n= number of samples examined. Significance *P<0.01

Data for biochemical parameters is shown in Table 2. A significant increase(P<0.01) in blood urea nitrogen (BUN) and alanine transaminase (ALT) levels were observed in parasitized than in non-parasitized group of animals. However, difference between the groups for creatinine and alkaline phosphatase levels were not significant. The increase in activity of ALT and BUN might be due to necrosis and fatty degeneration of liver (Soulsby, 1986). The rise in the activity of these biochemical parameters reflects severe muscle and liver damage due to migratory phase of the helminths. Similar trend of enzyme activity was also observed by Chaudhary and Iqbal (2000).

Table 2: Biochemical parameters in parasitized and non-parasitized dogs (mean+SE)

n= number of samples examined; Significance *P<0.01

CONCLUSION SHOULD BE A PARAGRAPH NOT ONE LINE

In conclusion, gastrointestinal helminthiasis results in haemato-biochemical alteration in dogs.

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