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 contortus, H. placei (R) • Brown stomach worm Ostertagia ostertagi (R) • Small stomach worm or hairworm 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) • 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 (H), (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) • 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.) • (R is intermediate host, D) • Dipylidium caninum (D, F) • Anophocephala perfoliata, A. magna (H) • Paranoplocephala mamillana (H) Trematodes (flukes) • (R) Deer liver fluke • Fascioloides magna (R) fluke • 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) • (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 • (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 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 blood containing lufenuron continue to lay eggs, but the eggs fail to develop normally Neonicotinoid • nitenpyram (Capstar®) • Neonicotinoid compound that binds and inhibits nicotinic acetylcholine receptors • Tablet that kills adult fleas within 30 minutes • Can safely give a dose as often as one per day • Can use on puppies and kittens older than 4 weeks and weighing more than 2 pounds Carbamates • carbaryl (Mycodex shampoo with • Act as a cholinesterase inhibitor, carbaryl®, Sevin Dust®, Adams Flea causing continual stimulation of and Tick Dust®) the postsynaptic neuron • May cause SLUDDE in animals (salivation, lacrimation, urination, defecation, dyspnea, and emesis) • Found in dusts, sprays, shampoos, and collars Table 15-5 Continued Fundamentals of Pharmacology for Veterinary Technicians Chapter 15

and • cythioate (Proban® tablets and liquid) systemic medications • diazinon (Escort®) • With oral products, fleas must bite animal to get medication Formamidines • amitraz (Mitaban® Dip, PrevenTIC® • Used for treatment of demodectic Collar, Taktic®) mange in dogs • Animals may show sedation for 24–72 hours following treatment • Toxic to cats and rabbits • Use gloves and protective clothing when applying to animals • Use in well-ventilated area Synergists • piperonyl butoxide • Have no activity against arthropods; • N-octyl bicycloheptene dicarboximide however, they increase the efficacy of pyrethrins and pyrethroids TABLE 15-5 Continued

Product Trade Name Examples Efficacy

Imidacloprid • imidacloprid (Advantage®) • Acts as an insect neurotoxin • Marketed for dogs and cats • Applied topically at the back of the neck, but is not absorbed into the blood • Kills adult fleas on contact • Has four-week residual effect Imidacloprid and permethrin • imidacloprid and permethrin • Works synergistically to rapidly (K9 Advantix®) paralyze and kill parasites • Kills fleas, mosquitoes, ticks (deer, American dog, Brown dog, lone star) Lime sulfur • lime sulfur (Lym Dyp®) • Provides antimicrobial and antiparasitic activity • Used in the treatment of sarcoptic mange • Also effective for the treatment of ringworm • May stain light-colored animals Table 15-5 Continued

Fundamentals of Pharmacology for Veterinary Technicians Chapter 15

• Residual activity even if dog is bathed • Labeled for fleas and ticks Repellents • DEET (Blockade®) • Used to repel mosquitoes, flies, • butoxypolypropylene glycol and gnats (VIP® Fly Repellent Ointment) • May be used in combination with pyrethrins and pyrethroids • Include sprays, ear tags,

Table 15-5 Continued Fundamentals of Pharmacology for Veterinary Technicians Chapter 15

TABLE 15-6 Drugs for Monthly (or Longer) Prevention of Fleas, Ticks, and Heartworm Disease Effective for Prevention Effective for Fleas Effective for Ticks of Heartworm Disease

permethrin (ProTICall®) permethrin (ProTICall®) imidacloprid (Advantage®) imidacloprid and permethrin (K9 Advantix®) selamectin (Revolution®) selamectin (Revolution®) selamectin (Revolution®) (labeled for American dog (also works on ear mites) tick only) nitenpyram (Capstar®) lufenuron (Program®) fipronil (Frontline®) fipronil (Frontline®) amitraz(PrevenTIC collar®) ivermectin (Heartgard®, Heartgard Plus®, Tri-Heart Plus® and Iverhart™ Plus) (Plus products also work on some intestinal parasites) milbemycin (Interceptor®) (also works on some intestinal parasites) milbemycin (Sentinel®) (also works on some intestinal parasites) Moxidectin (ProHeart®-6 works for six months)

Table 15-6 Fundamentals of Pharmacology for Veterinary Technicians Chapter 15

Figure 15-2