Prevalence and Chemotherapy of Parascaris equorum in Equines in Pakistan

CASE REPORT Prevalence and Chemotherapy of Parascaris equorum in Equines in Pakistan A. Khan, DVM, MPhil, M.S. Khan, DVM, PhD, M. Avais, DVM, MSc (Hons), A.K. Mahmood, DVM, MSc (Hons), and M. Ijaz, DVM, MPhil

ABSTRACT The prevalence of Parascaris equorum in paddock horses, donkeys, and mules (n ¼ 150 for each) of the Mona Remount Depot, Sargodha, Pakistan, was examined and the efficacy of two treatments, doramectin and garlic, measured on the basis of fecal egg counts. Parascaris equorum infection was found in 54 (36%) horses, 47 (31%) donkeys, and 42 (28%) mules. The final efficacy of treatment with doramectin was 92.5% in horses, 80.6% in donkeys, and 81.4% in mules, compared to 44.4%, 51,6%, and 37%, respectively, with garlic, making doramectin the more effective treatment. Keywords: Ascariasis; Doramectin; Garlic; Chemotherapeutic efficacy; Equidae; Fecal egg counts Parasitic infection is a major problem in raising equines. Factors such as continuous exposure to parasites, climatic conditions, and lack of knowledge on the part of livestock farmers regarding parasite transmission play an important role in sustaining parasitic diseases. Equines host a large quantity of parasites, both in terms of number of individual parasites and the number of species represented, sometimes with as many as 100,000 worms in a single animal.1 Equines are mainly infected by parasites of the families Ascarididae, Strongylidae, and Oxyuridae. Worms can affect all types of equines, whether stabled or on grass. A high density of horses per paddock increases infection incidence and intensity. Overgrazing forces horses to graze rough patches of grass growing around droppings. Inevitably, increasing numbers of worm eggs are passed in the droppings onto the pasture and ingested, leading to re-infection and high worm counts.2

From the Department of Clinical Medicine and Surgery, University of Veterinary and Animal Sciences, Lahore, Pakistan. Author contributions: The initiation, conception and planning of this project were by A. Khan, M. S. Khan, and M. Avais. Its execution was by A. Khan, M. Avais, and M. Ijaz. Writing of the paper and statistics were by A.K. Mahmood, A. Khan, M.S. Khan, M. Avais, and M. Ijaz. Reprint requests: A. Khan, DVM, MPhil, Department of Clinical Medicine and Surgery, University of Veterinary and Animal Sciences, Lahore, 54000, Pakistan. 0737-0806/$ - see front matter Ó 2010 Elsevier Inc. All rights reserved. doi:10.1016/j.jevs.2010.01.057

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Parascaris equorum (P. equorum), the causative parasite of ascariasis in equines, is a common and ubiquitous species that persists for many years in stables and on pasture in spite of good hygiene and anthelmintic treatment regimes. Among the factors influencing rearing of equines, ascariasis is the major problem which should be considered to have greater importance than other parasitic diseases.3 Ascarids have the greatest effect on young horses with naive immune systems,4 but are also responsible for substantial economic losses because of weight loss, failure of young horses to grow, and reduction in performance capabilities. Regular deworming aims to reduce the population to a critical point at which it becomes unstable and eventually interferes with the pre-patent period.5 An ideal anthelmintic shows a wide therapeutic index, wide spectrum of activity, and short residual period in the tissues.6 Doramectin is a veterinary drug approved by the Food and Drug Administration for the treatment of internal and external parasites of bovines and equines and is an avermectin derivative. In Pakistan, many equine owners consider garlic a viable alternative to commercial anthelmintics. It is readily available, appears to improve the health of the animals, and costs less than commercial preparations. This study investigated the prevalence of P. equorum and its treatment with doramectin and garlic in paddock horses, donkeys, and mules of the Mona Remount Depot, Sargodha.

MATERIALS AND METHODS A total of 450 fecal samples were collected from each of 150 horses, donkeys, and mules in the Mona Remount Depot. Feces were collected from the rectum and placed in sterile bottles for transport to the laboratory. Samples not tested immediately were held at 48C for no longer than 3 days. P. equorum eggs were identified on the basis of a key, using the direct smear method and salt flotation technique.7 Of the 54 horses, 42 donkeys, and 47 mules of mixed age, gender, and breed testing positive for P. equorum, 18 each of horses, donkeys, and mules were randomly selected and placed in three groups, A, B, and C. Each group was divided into three sub-groups of 6 (A1, A2, A3, B1, B2, B3, C1, C2, C3). Other subgroups A4, B4, and C4 each comprised six uninfected horses, donkeys, and mules,

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Table 1. Prevalence of Parascaris equorum in horses, donkeys, and mules from Mona Depot, Sargodha Pakistan Equine Species a

Horses Donkeysa Mulesa Total (%) a b

No. Examined at Age

No. Positive (%)

n

<2 Years

R2 Years

<2 Yearsb

R2 Yearsb

Total (%)

150 150 150 450

50 50 50 150

100 100 100 300

32 (64.0) 28 (56.0) 26 (52.0) 86 (57.3)

22 (22.0) 19 (19.0) 16 (16.0) 57 (19.0)

54 (36.0) 47 (31.3) 42 (28.0) 143 (31.8)

Nonsignificant difference (P > .05) among different species. Significant difference (P < .05) between age groups.

Table 2. Parascaris equorum Eggs g1 (EPG) in different groups at various days (Mean  SD) EPG gL1 Feces at Day Group

0*

3*

7*

14*

A1 A2 A3 A4 B1 B2 B3 B4 C1 C2 C3 C4

1000.00  63.25 1050.00  102.47 1350.00 128.45 0.00  0.00 2050.00  120.42 1600.00  184.40 1550.00  196.21 0.00  0.00 1600.00  184.40 1450.00  92.20 1350.00  128.45 0.00  0.00

250.00  92.20 750.00  102.47 1150.00  120.42 0.00  0.00 900.00  77.40 1050.00  128.45 1450  120.42 0.00  0.00 450.00  128.45 1100.00  63.25 1300.00  100.00 0.00  0.00

100.00  63.25 700.00  63.25 1000.00  100.00 0.00  0.00 200.00  100.00 750.00  67.08 1300.00  126.50 0.00  0.00 250.00  92.20 900.00  134.16 1100.00  100.00 0.00  0.00

100.00  63.25 750.00  102.47 1150.00  120.45 0.00  0.00 300.00  154.91 750.00  67.08 1300.00  167.33 0.00  0.00 250.00  120.42 850.00  92.20 1250.00  50.00 0.00  0.00

A1 horses treated with doramectin; A2 horses with garlic (Allium sativum); A3 horses as positive control; A4 as negative control; B1 donkeys treated with doramectin; B2 with garlic; B3 donkeys as positive control; B4 as negative control; C1 mules treated with doramectin; C2 treated with garlic; C3 mules as positive control; C4 as negative control. * Significant difference among groups at various days (P < .05).

Table 3. Comparative efficacy of doramectin and garlic Efficacy (%) at Day 3

7

14

Equine Species

Doramectin*

Garlic*

Doramectin*

Garlic*

Doramectin*

Garlic*

Horses Donkeys Mules

81.4 41.9 66.6

44.4 37.9 18.5

92.5 87.1 81.4

48.1 51.6 33.3

92.5 80.6 81.4

44.4 51.6 37.0

* Significant difference between two anthelmintics (P < .05).

respectively. Groups A1, B1, and C1 were treated with doramectin (Dectomex, Pfizer Pvt. Ltd., Pakistan) at 0.2 mg kg1 body weight (BW), groups A2, B2, and C2 were given garlic (Allium sativum) (National Garlic Powder, National Foods Pvt. Ltd., Pakistan) at 0.2 mg kg-1 BW. Groups A3, B3, and C3 served as positive controls, and groups A4, B4, and C4 were negative controls. Fecal samples were collected at day 0 (premedication) and on days 3,

7, and 14 (post-medication) for P. equorum egg counts. The number of P. equorum eggs per gram (EPG) of feces was calculated using the McMaster technique.7 The efficacy of drugs was calculated as described by Varady et al.8 Pretreatment EPG  Posttreatment EPG =pretreatment EPG  100

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Data were evaluated using the c2 test. P % .05 was considered significant.

RESULTS AND DISCUSSION Data on pretreatment prevalence of P. equorum are shown in Table 1. Of 450 equines, 143 (31.8%) contained P. equorum eggs. There were no significant differences among horses, donkeys, and mules, but significant differences were observed between the two age groups for all equines. Our findings are in agreement with the results of Lyons et al9 who found 42.9% prevalence of P. equorum in horses. In a more recent study, Lyons et al10 reported 39% prevalence in foals in Kentucky. Our results were also consistent with the findings of Ayele et al11 who reported 50% prevalence in Ethiopia. Vercruysse et al12 also observed 50% prevalence in Burkina Faso. Our findings are also supported by the results of Alani et al13 who recorded 63.3% prevalence in mules in Iraq. Tolliver et al14 recorded the prevalence of P. equorum as 50% in horses <2 year old and 23% in >2 year old horses, which was broadly consistent with our results. The increased prevalence of P. equorum in young equines may be due to the initial infection of foals from pastures and to coprophagy on farms. Furthermore, young animals have most likely had no, or infrequent, treatment with anthelmintics.14,15 Gawor16 has cited improper dosages of anthelmintics as a basic problem in young animals. The EPG in various groups are shown in Table 2. A significant decrease (P < .05) in EPG was observed in groups A1, A2, B1, B2, C1, and C2 compared with control groups A3, B3, and C3. The therapeutic efficacy of doramectin and garlic is given in Table 3. The efficacy of doramectin was significantly higher (P < .05) than that of garlic. The efficacy of doramectin and garlic in horses, donkeys, and mules showed a nonsignificant difference (P > .05) among species. Doramectin belongs to the avermectin group of macrocyclic lactone compounds of which ivermectin is another. Our results are in agreement with those of Yazwinski et al,17 who reported 100% efficacy of ivermectin against adult P. equorum and 98.5% against immature P. equorum. Similarly, Dipietro et al18 recorded the efficacy of ivermectin to be 100% against experimentally induced P. equorum infection in pony foals. Our findings are also consistent with those of French et al,19 who reported 100% efficacy of ivermectin against P. equorum in foals of ponies and horses. Seri et al20 also observed 100% efficacy of ivermectin against P. equorum in donkeys, which is in close agreement with our findings. Sutton and Haik21 reported that garlic was ineffective in decreasing the fecal ova counts in donkeys. They suggested that it simply may not be effective or that the extraction

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method or dose was inappropriate. In the present study, garlic powder was given orally at the dose rate of 0.2 g kg1 BW, following Blumenthal et al22 and Pearson et al,23 but efficacy was low in all the equines. The reason for low efficacy may be insufficient availability of allicin, the antiparasitic constituent of garlic. Further study of garlic is required to determine an effective dose and frequency of treatment. No side effect or adverse reaction to the injection of doramectin or oral administration of garlic was observed. It was concluded that P. equorum is of considerable concern as an infection of young horses, donkeys, and mules in the study population, and that doramectin is an effective treatment. ACKNOWLEDGMENT The authors thank the Mona Remount Veterinary Farms Corps (RVFC) for their support and collaboration in conducting this research.

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