Asmita Narang1, Niddhi Arora2 and V.S. Rajora3
1M.V.Sc. Student, 2Associate Professor and 3Professor; Department of Veterinary Medicine; College of Veterinary and
Animal Sciences; G.B. Pant University of Agriculture and Technology, Pantnagar-263145, U.S. Nagar (Uttarakhand).
[Received: 01.5.2017; Accepted: 20.11.2017]
w/v) applied topically in 18 dogs diagnosed
with clinical generalized demodicosis (Fourie
et al., 2013) reported. The present study was
envisaged to study the therapeutic efficacy of
amitraz pour-on against ectoparasites in dogs.The present work aimed to study the therapeutic efficacy of amitraz pour-on applied topically against canine
acariasis in `12 dogs. Diagnostic methods considered for ticks/fleas/lice were coat and skin evaluation and microscopic examination for mites. The clinical examination of the dogs was performed at an interval of 7 days with minimum of 21 days and maximum of 42 days upto two negative scrapings and evaluation of samples for hemato-biochemical profiles at pre and post treatment in various groups. Therapeutic study was done on the basis of disappearance of clinical manifestations, recovery rate, return of hemato-biochemical profiles to normal at post treatment. Clinicotherapeutic study showed 100% recovery post treatment against ticks/fleas and lice infestation with amitraz pour-on. However, in mange infestation, amitraz pour-on was clinically efficacious to 50 % recovery.
Key words: Amitraz, Canine, Ectoparasites, Pour-on.
Acariasis is one of the most common problem in canines. Mites cause variable skin diseases characterized by inflammation, pruritis and lesions. Sarcoptic mange has a zoonotic significance. Demodicosis is a parasitic inflammatory skin disease of dogs caused by an excessive proliferation of Demodex canis. A small number of mites
may constitute a normal component of the dog’s skin fauna (Ravera et al., 2013) but a proliferation of mites can lead to serious disease. Lice, fleas and ticks cause restlessness, intense pruritis and alopecia making the skin susceptible to secondary infections (Attri, 2003). When ectoparasites are vectors or intermediate hosts of bacterial, rickettsial or parasitic diseases, they become even more important. A protracted skin disease is often difficult to control due to its chronicity and recurrence, and may require persistent efforts and long duration of therapy. Amitraz dip concentrate is superior to deltamethrin and ivermectin in in treatment of Demodex affected pups (Nayak et al.,
2000). The high efficacy of metaflumizone plus amitraz spot-on formulation (ProMeris Duo) against generalized demodectic mange in a two year-old male dog (Tarallo et al., 2009). A 100% parasitological efficacy of Certifect (containing fipronil 6.26% w/v, amitraz 7.48% w/v, (S)-methoprene 5.63% w/v) applied topically in 18 dogs diagnosed with clinical generalized demodicosis (Fourie et al., 2013) reported. The present study was envisaged to study the therapeutic efficacy of amitraz pour-on against ectoparasites in dogs.
Materials and Methods
Animals brought to the Teaching Veterinary Clinical Complex, Pantnagar for various skin infections were routinely
subjected to clinical examination and skin scrapping examination. Twelve dogs irrespective of sex, age and breed confirmed for ectoparasitic dermatitis were included randomly in the present study. Moderate to severely ticks/fleas or lice infested and mange affected dogs constituted Group A and Group B (n=6) respectively. Diagnostic methods
considered for ticks/fleas or lice infestation were skin coat evaluation through physical/visual examination and clinical manifestations, whereas microscopic examination of superficial and deep skin scrapings were done to detect mites. The severity of infestation was designated as Very severe (++++), Severe (+++), Moderate (++), Mild (+). The hemato-biochemical studies were carried out to know the effect of various dermatological agents on the affected dogs and compared with the healthy control (Group C, n=6) dogs at pre and post treatment period. About 2 ml of blood sample was collected from cephalic vein of each dog and transferred to EDTA vials for the analysis of
blood cellular components within 2 hours of collection, deploying standard laboratory procedures. Biochemical analysis was done for glucose, protein profiles, enzymes and microminerals from the serum samples.
The amitraz pour-on was administered at the dose rate of 1 mg/kg bwt. by pour on method topically at an interval of 7 days. The drug was poured over the dorsal midline to have good vascular supply and even distribution. The pour-on was administered for a maximum of 3 times in case of ticks, fleas or lice infestation whereas in case of mites infestation it was administered upto two negative skin scrapings in the affected dogs.
Results and Discussion
The results of clinical observations are presented in (Table-1). In treated dogs, scales, hyperkeratosis, excoriation and nodules resolved on day 7 of initiation of therapy whereas patches of alopecia, erythema and pruritis reduced considerably by day 14. There was complete elimination of ticks/fleas/lice on day 14 in all the dogs but one dog got rid off the ectoparasites on day 21. Our findings are in accordance with Estrada-Pena (2005), who found that amitraz concentrate provided a better control of ticks even in the case of high infestations and also with Sharma et al. (2008) who reported 53.74%, 81.03% and 98.43% of female tick mortality achieved at 24, 48 and 72 hours of
post treatment when amitraz dip concentrate applied topically in the treated group. Amitraz exerts its effect in part by inactivating an adenylate cyclase system in the target ectoparasites giving rise to increased nervous activity as also reported by Sandhu and Rampal, 2011). Pour-on formulation is probably better than amitraz dip concentrate possibly due to its less chances of toxicity to following licking by the dogs, as it is applied on the dorsal midline.
Moreover its application is easier than the dip concentrate which requires direct application by owners’ hands.
Hematological parameters including Hb, PCV, TEC, TLC, ESR and eosinophils showed significant differences (P<0.05) in the treated dogs on day 21 post treatment in comparison to pre treatment values and were comparable to values in healthy control (Table-3). The haemoglobin concentration, PCV and total erythrocyte
counts were significantly lower in ticks/fleas/lice infestation and mange infestation. The decrease in Hb in the affected animals was probably due to decrease in total erythrocytes as a result of blood loss due to blood sucking behavior of ectoparasites causing anaemia in the affected host as also reported by Biswas and Roy (2005) who have
also observed significantly lower mean haemoglobin in demodectic dogs and Chhabra et al. (2000) reported significantly low PCV levels Sarcoptes scabiei infested dogs.. The TLC values increased significantly in both the groups. The leucocytosis might be explained as an allergic reaction caused by the mites and their products, inflammatory reactions or stress of parasitism in affected dogs. In case of ectoparasite infestation, eosinophilia might have contributed to leucocytosis. Stress may also be a possible reason. The differential leukocyte count
showed a non significant alteration for all the cells except eosinophils in both the groups. The eosinophil count was significantly higher in both the groups. Eosinophilia was attributed to large number of mites representing a highly significant antigen concentration and the consequent antigen antibody reaction. There was a significant increase in ESR in both the groups. Increase in ESR owed to decrease in TEC and increase in serum globulins. Due to anaemia, less number of cells settle more easily in the large volume of fluid indicating immature forms of erythrocytes. Simillar findings were reported by Benjamin (2010) who had reported that the alterations in globulins were directly
proportional to the ESR. Protein profiles of group A showed significant increase (P<0.05) in serum total proteins, albumin and A:G ratio and decrease in globulins on day 21 after initiation of therapy as compared to their pre
treatment values and were almost similar to healthy control (Table-4). There was a significant increase in serum total protein and globulins, and a significant decrease in both the groups. The increased values in total proteins might be due to increased immunoglobulins and circulatory immune responses.Initiation of recovery was observed
on day 7 post therapy when four dogs recovered completely and thereafter one recovered on day 14 and one on day 21 after treatment showing 100% recovery (Table-1).
In group B, the mange affected dogs were treated with amitraz pour-on at the dose rate of 1 mg/kg bwt. by pour on method at an interval of 7 days. The results of clinical observations of post treatment are presented in (Table-2). The clinical improvement in dogs of group B started on day 7 when number of mites started decreasing in the skin
scrapings along with reduction in erythema, folliculitis, papules, vesicles, pustules, crusts, scales and improvement in hyperkeratosis, rough hair coat, lichenification and nodules. There was complete elimination of mites from the skin scraping of three dogs on day 28. However, rest three dogs in group B remained affected upto day 42. In two dogs, the clinical manifestations got exaggerated where we had to switch over to injectable ivermectin.
Haemoglobin and TLC values in affected dogs post treatment with amitraz pour-on differed significantly (P<0.05) from pre treatment values as well as healthy values and did not show any improvement on day 35 after institution of therapy. Post treatment values for PCV, TEC and ESR were non significantly different than pre treatment
values (Table-3). Biochemical profiles of group B showed non significant differences (P<0.05) in pre and post treatment values (Table-4) for blood glucose, AST, serum copper, zinc and manganese. However, serum total proteins and albumin showed values similar to healthy group. Serum globulins, A:G ratio and ALT values were significantly different (P<0.05) in comparison to their pre treatment values and healthy control values
(Table-4). The activity of serum enzyme alanine amino transferase and alanine amino transferase increased significantly in mange. The increased liver specific enzymes were attributed to the hepatic damage caused by
the toxic byproducts of tissue breakdown. So topical preparations are also effective like injectable preparations. The authors could not find any citation on the efficacy of amitraz pour-on formulation on mange infested dogs.
Out of six, three dogs showed complete improvement showing only 50% recovery and it may be due to only once weekly application of pour-on when generalized infection require more intensive therapy.
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