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Activity of praziquantel (0.5 mg kg−1) against Anoplocephala perfoliata (Cestoda) in equids
veterinary parasitology ELSEVIER
Veterinary Parasitology 56 (1995) 255-257
Short communication
Activity of praziquantel (0.5 mg kg- ) against Anoplocephala perfoliata ( Cestoda ) in equids E.T. Lyons*, S.C. Tolliver, S. Stamper, J.H. Drudge, D.E. Granstrom, S.S. Collins Department of VeterinaryScience, GluckEquine Research Center, Universityof Kentucky, Lexington, KY40546-0099, USA Accepted 28 January 1994
Abstract Praziquantel injectable formulation was administered at 0.5 mg kg- i per os to 24 equids naturally infected with 1-183 (average 40) Anoplocephala perfoliata. Drug activity was evaluated by a modified critical test method with necropsy 24 h after treatment. There was variable efficacy of 0-100% (aggregate average 85%); for 18 equids, 93-100%, for three equids, 70-85%, and for three equids, 0-20%.
Keywords:Anoplocephalaperfoliata; Horse; Control methods-Cestoda; Praziquantel
1. Introduction The tapeworm, Anoplocephala perfoliata, has been incriminated as a cause of several health problems in equids (Lyons et al., 1992). Two drugs, pyrantel pamoate and praziquantel, have been investigated recently by the present authors to determine efficacies against A. perfoliata (Lyons et al., 1986, 1989, 1992). The purpose of the research reported here was to evaluate the activity of praziquantel against this parasite at a lower dose rate (0.5 mg kg- 1) than previously tested. 2. Materials and methods
Between 30 October 1990 and 22 June 1993, praziquantel (Droncit ® Injectable; Miles Inc., Shawnee Mission, KS), on the market in the USA for dogs and * Corresponding author" Tel. (606) 257-3873; Fax. (606) 257-8542. 0304-4017/95/$09.50 © 1995 Elsevier Science B.V. All rights reserved SSD1 0304-4017 (94) 00661 -X
E.T. Lyons et al. / Veterinary Parasitology 56 (1995) 255-25 7
256
cats, was administered per os at 0.5 mg kg- ~to 42 equids. Determination of infection of the equids with .4. perfoliata was not attempted before treatment because of the difficulty in finding tapeworm eggs in feces. A modified critical test (24 h ) was used for evaluation of activity of praziquantel (Todd and Brown, 1952; Lyons et al., 1986, 1989). Specific details have been published (Lyons et al., 1986, 1989). Briefly, if specimens of.4. perfoliata are found at necropsy, 24 h post treatment, attached to the mucosa or in the contents of the small intestine and cecum, or attached to the mucosa of the ventral colon, they are considered as not removed by the drug. If they are recovered from the contents of the ventral colon, dorsal colon, small colon, and rectum, they are assumed to be removed by the drug. The basis for these assumptions is that .4. perfoliata is normally an inhabitant of the cecum, but can occasionally be present in the small intestine and ventral colon. The types of equids used in the tests ( n = 4 2 ) were Thoroughbred ( n = 2 9 ) , mixed lighthorse (n = 9), Shetland pony (n = 1 ), Welsh pony (n = 1 ), Standardbred (n = 1 ), and Trakehner (n = 1 ). They were cull animals; most were donated and included several wobblers. Sexes included 21 males (intact), five geldings, 15 females, and one animal whose sex was not recorded. Ages varied from less than l to over 22 years old (less than 1 year, n = l; 1 year, n = 18; 2 years, n = 7 ; 3 years, n = 3 ; 4 years, n = 3 ; 6 years, n = 2 ; 8 years, n = l; l0 years, n = l; 14 years, n = 1; 17 years, n = l; 22 years, n = 1; over 22 years, n = 3 ).
3. Results and discussion Twenty-four of the 42 (58%) treated equids were positive for I to 183 (average 40) A. perfoliata at necropsy. Efficacies in the 24 infected animals varied from 0 to 100% (aggregate average 85%). Individual efficacies were: 0% ( n = 2 ) , 20% ( n = 1 ), 70% ( n = 1 ), 80% ( n = 1 ), 85% ( n = 1 ), 93% ( n = 1 ), 94% ( n = 1 ), 96% ( n = 1 ), 97% ( n = 1 ), 98% ( n = 2 ) , and 100% ( n = 12). Summarily, removals were 93-100% for 18 equids, 80% and 85% for two, 70% for one, and 20% or less for three animals (Table 1 ). In the present tests, no definite explanation can be made for the variability in Table 1 Data for Anoplocephala perfoliata recovered from 24 equids treated with praziquantel injectable formulation at 0.5 mg kg-J per os in modified critical tests. The data presented are the range, with the mean in parentheses No. of equids
24
No. ofspecimens
Percent removal
Remaining Removed
Total
0-11 (1.58)
1-183 (39.75)
"Aggregate.
0-172 (38.2)
0-100 (85)"
Clearance 0-20%
70-85%
93-98%
100%
3
3
6
12
E.T. Lyons et al. / VeWrinary Parasitology 56 (1995) 255-257
257
efficacy of praziquantel at the 0.5 mg kg- ~dose rate. It is believed that one equid, for which removal was 0%, and harboring only one tapeworm specimen, possibly spit out the drug. However, there was no indication that the other animals with low efficacies ejected any drug after treatment. Previous testing of praziquantel at higher doses (0.75 and 1.0 nag kg -~ ) indicated higher aggregate average efficacies (Lyons et al., 1992). Aggregate average removals of A. perfoliata at 0.75 nag kg -~ were 91% and at 1.0 nag kg -1 were 98% or over. However, the lowest removal activity for the 0.75 and 1.0 mg kg- ~ dose rates (82%) was higher than for the 0.5 mgkg -~ dose rate (0%). Prevalence of A. perfoliata was 58% in the present tests, 66% for Thoroughbreds and 39% for non-Thoroughbreds. Most of the prevalence studies on this parasite species in this geographical area have been on dead Thoroughbreds, of which about 50-60% have been found to be infected (Lyons et al., 1992). Whether the somewhat higher infection rate for Thoroughbreds in the present tests is really indicative of an increase or that too low a number of equids was sampled for a more accurate measure of prevalence is unknown.
Acknowledgments Published as Paper No. 92-4-219 in connection with a project of the Kentucky Agricultural Experiment Station, with the approval of the director. The authors thank Miles Inc., Shawnee Mission, KS for supplying the praziquantel.
References Lyons, E.T., Drudge, J.H., Tolliver, S.C. and Swerczek, T.W., 1986. Pyrantel pamoate: Evaluating the activity against equine tapeworms. Vet. Med., 81: 280-285. Lyons, E.T., Drudge, J.H., Tolliver, S,C., Swerczek, T.W. and Collins, S.S., 1989. Determination of the efficacy of pyrantel pamoate at the therapeutic dose rate against the tapeworm Anoplocephala perfoliata in equids using a modification of the critical test method. Vet. Parasitol., 31: 13-18. Lyons, E.T., Tolliver, S.C., Drudge, J.H., Granstrom, D.E. and Stamper, S., 1992. Activity of praziquantel against Anoplocephala perfoliata (Cestoda) in horses. J. Helminthol. Soc. Wash., 59: 1-4. Todd, A.C. and Brown, R.G., 1952. Critical tests with toluene for ascarids and bots in horses. Am. J. Vet. Res., 13: 198-200.
Veterinary Parasitology 56 (1995) 255-257
Short communication
Activity of praziquantel (0.5 mg kg- ) against Anoplocephala perfoliata ( Cestoda ) in equids E.T. Lyons*, S.C. Tolliver, S. Stamper, J.H. Drudge, D.E. Granstrom, S.S. Collins Department of VeterinaryScience, GluckEquine Research Center, Universityof Kentucky, Lexington, KY40546-0099, USA Accepted 28 January 1994
Abstract Praziquantel injectable formulation was administered at 0.5 mg kg- i per os to 24 equids naturally infected with 1-183 (average 40) Anoplocephala perfoliata. Drug activity was evaluated by a modified critical test method with necropsy 24 h after treatment. There was variable efficacy of 0-100% (aggregate average 85%); for 18 equids, 93-100%, for three equids, 70-85%, and for three equids, 0-20%.
Keywords:Anoplocephalaperfoliata; Horse; Control methods-Cestoda; Praziquantel
1. Introduction The tapeworm, Anoplocephala perfoliata, has been incriminated as a cause of several health problems in equids (Lyons et al., 1992). Two drugs, pyrantel pamoate and praziquantel, have been investigated recently by the present authors to determine efficacies against A. perfoliata (Lyons et al., 1986, 1989, 1992). The purpose of the research reported here was to evaluate the activity of praziquantel against this parasite at a lower dose rate (0.5 mg kg- 1) than previously tested. 2. Materials and methods
Between 30 October 1990 and 22 June 1993, praziquantel (Droncit ® Injectable; Miles Inc., Shawnee Mission, KS), on the market in the USA for dogs and * Corresponding author" Tel. (606) 257-3873; Fax. (606) 257-8542. 0304-4017/95/$09.50 © 1995 Elsevier Science B.V. All rights reserved SSD1 0304-4017 (94) 00661 -X
E.T. Lyons et al. / Veterinary Parasitology 56 (1995) 255-25 7
256
cats, was administered per os at 0.5 mg kg- ~to 42 equids. Determination of infection of the equids with .4. perfoliata was not attempted before treatment because of the difficulty in finding tapeworm eggs in feces. A modified critical test (24 h ) was used for evaluation of activity of praziquantel (Todd and Brown, 1952; Lyons et al., 1986, 1989). Specific details have been published (Lyons et al., 1986, 1989). Briefly, if specimens of.4. perfoliata are found at necropsy, 24 h post treatment, attached to the mucosa or in the contents of the small intestine and cecum, or attached to the mucosa of the ventral colon, they are considered as not removed by the drug. If they are recovered from the contents of the ventral colon, dorsal colon, small colon, and rectum, they are assumed to be removed by the drug. The basis for these assumptions is that .4. perfoliata is normally an inhabitant of the cecum, but can occasionally be present in the small intestine and ventral colon. The types of equids used in the tests ( n = 4 2 ) were Thoroughbred ( n = 2 9 ) , mixed lighthorse (n = 9), Shetland pony (n = 1 ), Welsh pony (n = 1 ), Standardbred (n = 1 ), and Trakehner (n = 1 ). They were cull animals; most were donated and included several wobblers. Sexes included 21 males (intact), five geldings, 15 females, and one animal whose sex was not recorded. Ages varied from less than l to over 22 years old (less than 1 year, n = l; 1 year, n = 18; 2 years, n = 7 ; 3 years, n = 3 ; 4 years, n = 3 ; 6 years, n = 2 ; 8 years, n = l; l0 years, n = l; 14 years, n = 1; 17 years, n = l; 22 years, n = 1; over 22 years, n = 3 ).
3. Results and discussion Twenty-four of the 42 (58%) treated equids were positive for I to 183 (average 40) A. perfoliata at necropsy. Efficacies in the 24 infected animals varied from 0 to 100% (aggregate average 85%). Individual efficacies were: 0% ( n = 2 ) , 20% ( n = 1 ), 70% ( n = 1 ), 80% ( n = 1 ), 85% ( n = 1 ), 93% ( n = 1 ), 94% ( n = 1 ), 96% ( n = 1 ), 97% ( n = 1 ), 98% ( n = 2 ) , and 100% ( n = 12). Summarily, removals were 93-100% for 18 equids, 80% and 85% for two, 70% for one, and 20% or less for three animals (Table 1 ). In the present tests, no definite explanation can be made for the variability in Table 1 Data for Anoplocephala perfoliata recovered from 24 equids treated with praziquantel injectable formulation at 0.5 mg kg-J per os in modified critical tests. The data presented are the range, with the mean in parentheses No. of equids
24
No. ofspecimens
Percent removal
Remaining Removed
Total
0-11 (1.58)
1-183 (39.75)
"Aggregate.
0-172 (38.2)
0-100 (85)"
Clearance 0-20%
70-85%
93-98%
100%
3
3
6
12
E.T. Lyons et al. / VeWrinary Parasitology 56 (1995) 255-257
257
efficacy of praziquantel at the 0.5 mg kg- ~dose rate. It is believed that one equid, for which removal was 0%, and harboring only one tapeworm specimen, possibly spit out the drug. However, there was no indication that the other animals with low efficacies ejected any drug after treatment. Previous testing of praziquantel at higher doses (0.75 and 1.0 nag kg -~ ) indicated higher aggregate average efficacies (Lyons et al., 1992). Aggregate average removals of A. perfoliata at 0.75 nag kg -~ were 91% and at 1.0 nag kg -1 were 98% or over. However, the lowest removal activity for the 0.75 and 1.0 mg kg- ~ dose rates (82%) was higher than for the 0.5 mgkg -~ dose rate (0%). Prevalence of A. perfoliata was 58% in the present tests, 66% for Thoroughbreds and 39% for non-Thoroughbreds. Most of the prevalence studies on this parasite species in this geographical area have been on dead Thoroughbreds, of which about 50-60% have been found to be infected (Lyons et al., 1992). Whether the somewhat higher infection rate for Thoroughbreds in the present tests is really indicative of an increase or that too low a number of equids was sampled for a more accurate measure of prevalence is unknown.
Acknowledgments Published as Paper No. 92-4-219 in connection with a project of the Kentucky Agricultural Experiment Station, with the approval of the director. The authors thank Miles Inc., Shawnee Mission, KS for supplying the praziquantel.
References Lyons, E.T., Drudge, J.H., Tolliver, S.C. and Swerczek, T.W., 1986. Pyrantel pamoate: Evaluating the activity against equine tapeworms. Vet. Med., 81: 280-285. Lyons, E.T., Drudge, J.H., Tolliver, S,C., Swerczek, T.W. and Collins, S.S., 1989. Determination of the efficacy of pyrantel pamoate at the therapeutic dose rate against the tapeworm Anoplocephala perfoliata in equids using a modification of the critical test method. Vet. Parasitol., 31: 13-18. Lyons, E.T., Tolliver, S.C., Drudge, J.H., Granstrom, D.E. and Stamper, S., 1992. Activity of praziquantel against Anoplocephala perfoliata (Cestoda) in horses. J. Helminthol. Soc. Wash., 59: 1-4. Todd, A.C. and Brown, R.G., 1952. Critical tests with toluene for ascarids and bots in horses. Am. J. Vet. Res., 13: 198-200.