Fundamentals of Pharmacology for Veterinary Technicians Chapter 15 Helminths Nematodes Platyhelminths Cestodes Trematodes Figure 15-1 Fundamentals of Pharmacology for Veterinary Technicians Chapter 15 TABLE 15-1 Helminths Encountered in Veterinary Medicine Scientific and Main Category Location of Parasite Commo Names Nematodes Abomasal worms in ruminants or stomach • Barberpole worm Haemonchus worms in monogastric animals contortus, H. placei (R) • Brown stomach worm Ostertagia ostertagi (R) • Small stomach worm or hairworm Trichostrongylus axei (R, H) • Hyostrongylus rubidus (Sw) • Large-mouth stomach worm Habronema muscae (H) Intestinal worms • Small intestinal worms Cooperia punctata, C. oncophora, C. mcmasteri (R) • Hookworms Bunostomum phlebotomum (R), Ancylostoma sp (D, F) • Nodular worms Oesophagostomum spp. (R, Sw) • Thread-necked intestinal worm Nematodirus helvetianus (R) • Bankrupt worm Trichostrongylus colubriformis (R) • Large strongyles Strongylus vulgaris, S. edentatus, S. equinus, Triodon- tophorus spp. (R, E) • Small strongyles Cyathostomum spp., Cylicocyclus spp., Cylicostephanus spp., Cylicodontophorus spp. (R) • Whipworms Trichuris suis (Sw), Trichuris vulpis (D) • Threadworms Strongyloides ransomi (Sw), Strongyloides westeri (E), Table 15-1 Fundamentals of Pharmacology for Veterinary Technicians Chapter 15 Strongyloides stercoralis (D) • Ascarids Parascaris equorum (H), Toxocara canis (D), Toxocara cati (F), Toxascaris leonina (D, F) • Pinworms Oxyuris equi (E) Circulatory systems worms • Heartworms Dirofilaria immitis (D, F) Lungworms • Dictyocaulus spp. (R, H) • Prostostrongylus rufescens (S, G) • Muellerius capillaris (S, G) • Metastrongylus spp. (Sw) Kidney worms • Stephanurus dentatus (Sw) Gastrointestinal and skin • Habronema spp., worms Draschia worms spp., Onchocerca spp. (H) Cestodes (tapeworms) • Moniezia benedeni (R) • Taenia spp. (R, D, F) TABLE 15-1 Continued Scientific and Main Category Location of Parsite Commo Names Cestodes (tapeworms) (cont.) • Echinococcus granulosus (R is intermediate host, D) • Dipylidium caninum (D, F) • Anophocephala perfoliata, A. magna (H) • Paranoplocephala mamillana (H) Trematodes (flukes) Liver fluke • Fasciola hepatica (R) Deer liver fluke • Fascioloides magna (R) Lung fluke • Paragonimus kellicotti (D, F) Protozoa • Coccidia Eimeria spp. (R, Sw, H) • Coccidia Isospora spp. (Sw, D, F) • Toxoplasma gondii (F) • Giardia spp. (R, H, D, F) • Cryptosporidium spp. (R, Table 15-1 Continued Fundamentals of Pharmacology for Veterinary Technicians Chapter 15 H) • Sarcocystis spp. (R in muscle; D, F shed in stool) • Tritrichomonas foetus (C in reproductive tract) R = ruminants, C = cattle, S = sheep, G = goats, Sw = swine, D = dogs, F = cats, H = horses Table 15-1 Continued Fundamentals of Pharmacology for Veterinary Technicians Chapter 15 TABLE 15-2 Types of Antiparasitic Drugs Benzimidazoles (nematodes) • thiabendazole • oxibendazole • mebendazole (also works on tapeworms) • fenbendazole (also works on tapeworms and flukes) • albendazole (also works on tapeworms, flukes, and giardia) • oxenfendazole (also works on tapeworms and flukes) • febantel (a probenzimidazole used in combination with other products to broaden its spectrum of activity) Imidazothiazoles (nematodes) • levamisole Tetrahydropyrimidines (nematodes) • pyrantel pamoate • pyrantel tartrate • morantel tartrate Organophosphates (nematodes; ectoparasites, including bots) • trichlorfon • dichlorvos • coumaphos Piperazines (nematodes) • piperazine dihydrochloride • piperazine sulfate Macrocyclic lactones (nematodes; heartworm prevention; ectoparasites, such as bots and grubs) • ivermectin • eprinomectin • selamectin • moxidectin • milbemycin oxine • doramectin Pyrazine derivatives • praziquantel (tapeworms, flukes) • epsiprantel (tapeworms) Benzenesulfonamide (flukes) • clorsulon Coccidiostats (coccidia) • sulfadimethoxine • amprolium • decoquinate • nicarbazine • monensin • robenidine Nitroimidazoles (Giardia) • metronidazole Table 15-2 Fundamentals of Pharmacology for Veterinary Technicians Chapter 15 TABLE 15-3 Administration Routes for Anthelmintics Main Route Example Route Description Concerns Oral Tablets May be hard tablet, chewable tablet, • Allows greater control over amount or bolus (large pill) that animal ingests of drug given or is given • Palatability is important (especially with cats and horses) Liquid May be in the form of a solution, • Drug must be shaken well to ensure suspension paste, paste syringe, or adequate mixing of chemical drench throughout the liquid • Paste syringes contain a precalibrated amount of paste that need not be shaken Oral • Drenches are liquid forms given by mouth that force the animal to drink • Allows greater control over amount of drug given Feed additives May be in feed, added to mineral • Treats parasites in large numbers mixes, added to drinking water or of animals added to salt blocks • Allows little control over amount of drug ingested by an individual animal • Is stress-free for the animals • Saves expense of rounding up livestock Sustained-release Device is implanted in rumen to allow • Saves time in retreating of animals slow release of the drug over time • Can treat animals over a period (especially helpful in treating later (like the complete grazing season) stages of parasite larvae) Injectable Solution Given SQ usually (if given IM, may • Easy way to administer affect the carcass) • Local reaction is possible, but is rare • Allows greater control over amount of drug given • Achieves higher blood levels rapidly • Requires livestock to run through chutes or be Table 15-3 Fundamentals of Pharmacology for Veterinary Technicians Chapter 15 TABLE 15-4 Application Methods for Ectoparasiticides Type of Product Advantages Disadvantages Prediluted sprays • Convenient and easy to use (apply • Water-based sprays do not penetrate (include sprays for animals and premise from head to tail, avoiding eyes, oily coats or fabrics well sprays) mouth, and nose) • Alcohol-based sprays may be • Usually has quick kill drying and irritating to skin • May have residual effects • Available for animal and environment Concentrated Sprays • Concentrated form may offer cost • Error in dilution may occur savings • Diluted product may not have long • Can be diluted at different shelf life concentrations for different ectoparasites Yard spray/Kennel spray • Offer residual effects • Can only be used on Table 15-4 Fundamentals of Pharmacology for Veterinary Technicians Chapter 15 Dips • Offer residual effects • Must be diluted properly • Animal should be shampooed first • Animal must dry with dip product on—cannot rinse TABLE 15-4 Continued Type of Product Advantages Disadvantages Pour-ons • Can ensure that an individual animal • Activity of drug may be limited if is treated applied to unclean animal (e.g., • May treat many animals at a time animal with caked mud or manure with proper application devices on its hide) • May be applied incorrectly, resulting in limited value of the treatment or development of toxicity (application varies; may be along the backline from shoulders to the hip bones or in single spot) Shampoos • Rinse well • May only contain products for • May contain medication effective cleaning the coat against parasites • No residual effect even if medication present • May have to be diluted before use • Must leave on animal for a specified time prior to rinsing Dusts or powders • Can be used in animals that do not • Do not provide quick kill tolerate sprays • May irritate and dry skin Foggers • Work well in large, open rooms • Product does not get everywhere • Quick method for environmental needed can be improved if (corners, control furniture); this premise spray is used with the fogger • Can be toxic to fish; must cover food products when applying Oral products • No mess • May not kill all stages of Table 15-4 Continued Fundamentals of Pharmacology for Veterinary Technicians Chapter 15 TABLE 15-5 Chemical Products for Ectoparasite Control Product Trade Name Examples Efficacy Pyrethrins and pyrethroids • pyrethrin (Mycodex Shampoo®) • Very safe • Names end in -rin or -thrin • d-trans allethrin (Duocide Spray®) • Quick kill • Pyrethrins are natural plant products • permethrin (ProTICall®) • Often manufactured with other • Pyrethroids are synthetic pyrethrins products • May have limited residual effects • Form labeled for dogs may be too high a concentration for cats • Commonly used in sprays, dips, fogger, insecticidal ear tags, and premise sprays Insect growth regulators (IGR): • methoprene (Ovitrol® and Siphotrol®) • Products with IGR provide the Include insect development inhibitors • pyriproxyfen (Nylar®) flea with high levels of IGR, Table 15-5 Fundamentals of Pharmacology for Veterinary Technicians Chapter 15 and juvenile hormone mimics • fenoxycarb; pulled from the market which mimics the insect’s juvenile because it breaks down to hormone (JH). Fleas need low levels formaldehyde, a carcinogen of JH to molt to the next stage; high levels interrupt normal molting, so the insect stays in the larval stage and eventually dies TABLE 15-5 Continued Product Trade Name Examples Efficacy Insect growth regulators (IGR) • Do not have adulticide activity (cont.) • Found in sprays and flea collars Chitin synthesis inhibitor • lufenuron (Program®) • Chitin is an insect protein that gives strength and stiffness to its body; chitin synthesis inhibitors prevent proper formation of this protein • Lufenuron is given orally to dogs and orally or SQ to cats • Fleas that feed on