Antiparasitics

organism that lives in or on another organism at its expense

live on surface of animal's body; like ticks; cause infestations

live inside the animal's body; cause infections

• - sometimes on surface of animals
• - other times need to exam a fecal sample (eggs/larvae released in feces)

• - selectively toxic
• - no resistance
• - economical
• - effective against all stages

• - drugs that treat= antihelminthics
• - include nematodes and platyhelminths
• - not protozoa

• - cylindrical and nonsegmented
• - generally inhabit GIT
• - filarial nematodes are a special group

• - flat worms
• - include cestodes (tapeworms) and trematodes (flukes)

• - single cell, not helminth
• - include coccidia, toxoplasmosis

• - infective larvae penetrate skin
• - infective larvae enter host transplacentally
• - host ingests infective larvae in food, colostrum, or milk

• 1. benzimidiazoles
• 2. tetrahydropyrimidines
• 3. piperazines
• 4. organophosphates
• 5. imidazothiazoles
• 6. macrocyclic lactones (macrolides)

• - include thiabendazole (has some antifungal properties), oxibendazole (equine past deworm), fenbendazole (Panacur), albendazole, Febantel (pro benizimadole)
• - low toxicity
• - attacks proteins necessary for cell divisions in parasites
• - problems with resistance
• - targets microtubules of all
• - liquid gran powder past

• - pyrantel- 2 forms
• - suspension
• - highly effective against hookworms and roundworms
• - only targets adults
• - classified as cholinergic agonist
• - parasympathomimetic ( targets ACh neurotransmitter, contractions)
• - if parasite is freely living and not attached it will be expelled
• - only acts within GI tract
• - also used in people with pinworms; horses get pinworms too

• - GABA agonists
• - OTC
• - roundworms
• - narrow spectrum
• - normal side effect: bolus of worms through vomit or defecation
• - MA: pump protein--> pump out Cl- --> into cell depolarize --> expel worm

• - used for ectoparasites
• - narrow range of safety
• - MA by irreversibly inhibiting acetylcholinesterase
• - end up with cholinergic signs: paralysis
• - cats more prone to OP toxicity-- dip
• - antidote for toxicity = atropine
• - used a lot in large animal pour-ons, powders
• - cholinergic crisis = salivation, lacrimation, urinating, diarrhea

• - only levamisol in large animals
• - cholinergic agonist; stimulating --> paralysis
• - same toxic side effects as OP
• - used in poultry

• - endectocide; broad spectrum against nematodes and get ectoparaistes like mites and lice
• - include avermectins and milbemycins
• - not effective against cestodes or trematodes
• - MA: induce spastic paralysis through GABA receptor at high concentrations
• - some effect at glutamate ion channels: hyperpolarization of parasite; muscle spasms; cannot move; parasites are washed away or attacked by immune cells
• - cause paralysis of pharygeal muscles of parasites
• - worms lack CNS

• - kills mites by paralyzing pharyngeal muscles
• - toxicity causes mutation of transporter proteins
• - accumulation = hyperpolarization and neurological problems
• - ivermectin hazardous to collies, australian shepherds, and sheep dogs

• -once/month preventative = low dose; not effective for L1/L4
• - significant disease in right side of heart leading to CHF
• - diagnosed by snap test or x-ray through enlargement of right side of heart
• - expensive to treat= arsenic cmpds for adult worms; restrained for 1-2 months to prevent thromboembolism
• - treatment also depends on if microfilaria is being produces

heartworm adulticide; deep intramuscular injection (back muscles)

- melarsomine dihydrochloride

macrocyclic lactones at high doses (extra label)

there is a risk of neurotoxicity with no antidote

antinematidal in large animals; given by injection and in horses given orally only

occurs when a greater # of individuals in a population are resistant or no longer affected by the medication; permanent

• - affects both small and large animals
• - not affected by macrocyclic lactones
• - thin end (head); proglottins (segments) packed full of eggs and passed in feces when shedding
• - each egg has immature head of tapeworm
• - suckers on head attach to mucosa of sm. intestine and absorb nutrients
• - parthenogenesis (need no mate)
• - infection through ingestion

• - attack the attachment site (scolex= head), causing paralysis, and worm gets purged through feces
• - causes an increase in calcium ion permeability, parasite loses calcium with is necessary for muscle contraction and relaxation
• - includes Praziquantel (Droncit), Epsiprantel (Cestex)
• - oral tablets

• - fasciola hepatica
• - great economic impact in cattle
• - unsegmented parasitic flat worms, visible to naked eye (1 cm in length)
• - lead to liver condemnation, unthriftiness and loss of condition in cattle
• - cysts in liver, adults reside in these cysts
• - intermediate host = snail
• - ingestion when grazing on pastures near ponds or natural water supply

• - includes praziquantel (used in sm animals to treat lung flukes), albendazole, and curatrem (colorsulon; main)
• - inhibits the energy production system of these parasits (glycolysis)
• - given by drench (oral solution)

class of organisms, single celled, eukaryotic

include giardia, coccidia, and sarcocystis neurona

• - intestinal protozoa; causes GI problems in young animals, diarrhea, scours in calves
• - problem in poultry
• - prevent by decreasing stocking #'s and increasing sanitization
• - parasite invade cell that line sm intestine, replicate, cell ruptures, release in lumen, infect other cells, and cells are not able to absorb nutrients which causes the diarrhea
• - treat with coccidistats: monensin which effects metabolism of protozoa
• - narrow spectrum: corid (amprolium) in large animal and sulfa antibiotic (albon) in cats and dogs

• - zoonotic disease, infect sm. intestine, epithelial stage
• - have flagella
• - diagnose with fecal elisa tests
• treat with fembendazol (panacur)
• - can treat with antimicrobial agent= flagel (metronidazole) but not approved yet; can lead to nausea/vomiting at high levels (neurotoxin); unpalatable for cats, effective against anaerobic microbes

• - protozoal disease cusing EPM (equine protozoal myolitis)
• - affects CNS of host
• - intermediate host = armadilos, raccoons, skunk
• - Definitive host = opposums
• - Dead end host = horse
• - drug: ponazuril which inhibits nuclear division in parasite (cocciostatic)
• - EPM: nurological signs, prevalent, muscle atrophy, lameness, CSF test, expensive

• - Albon (sulfadimethoxine)
• - Panacur (fenbendazole)
• - Flagyl (metronidazole)
• - Marquis (ponazuril)

• - Organophosphates and carbamates
• - pyrethrins and pyrethroids
• - macrolides
• - imidacloprid
• - frontline (Fipronil)
• - capstar (nitempyram)
• - program (lufeneron)
• - mitaban, preventic (amitraz)

• - Developed as nerve gas originally
• - Dips
• - Toxicity signs: (parasympathetic over stimulation), Hypersalivation, Defacation, Pupils dilation (mydriasis), Epiphora, will progress to muscle tremors/seizures

• - Mechanism of action: irrevesibly inhibit acetylcholinesterase causing paralysis; parasite falls off or is destroyed
• - Cats very sensitive; Antidote: atropine

• - safe; applied external (spray or dip)
• - Pyrethrins: natural products, toxic to fish, not a good kill effect on adults but great knockdown effect; MA: open Na+ channels in insects causing hyperpolarization

- Pyrethroids: synthetic; used as a room defogger to kill larval stages; cant penetrate eggs; good kill effect; can cause toxicity in cats; use on adult animals

- Insect growth regulators to prevent molting can be added--- mimic effect of juvenile growth hormone

• - Include selomectic (active ingredient in Revolution)
• - In ruminants by injection; horses= paste; drench; topically

• - Topically-- between shoulder blades; not absorbed systemically; Trifexis
• - Advantix in dogs has pyrethrin added; Advantage in cats

• - Not absorbed systemically
• - Interferes with nicotinic insect receptors
• - Gets into sebaceous gland --> 30 day absorbed
• - Nontoxic even if animals accidentally ingest
• - Alopecia or hair loss at site
• - Need a couple days to be absorbed and avoid touching area

• - oral
• - Kill adult fleas; absorbed systemically
• - Animals have to get bitten
• - Works well for maggot infestation in animals
• - Can be used in fly-strike in rabbits

• - chewable tablet
• - Inhibits insect growth by interfering with chitin

• - Preventic collar --> if ingested causes coma and lead to death; trim excess collar
• - Mitaban dip-- only approved product to treat demodectic mange in dogs (not all dogs respond to it); caused by demodex canis

• - CANNOT BE USED IN CATS
• - Miticidal; effective against ticks too
• - Highly toxic if ingested
• - Staff must wear personal protective equipment
• - Alpha2 receptor agonist (depresses norepinephrine)
• - See depression and sedation
• - MAO inhibitor (recycling norepi)
• - Antidote --> yohimbe
• - Milbomycin works better than ivermectin

• - Demodectic: Live in hair follicles; causes hair loss; inflammation; severe skin infestation; bacterial infection; Genetic: neuter or spayed a must
• - Another type of mange is sarcoptic mange: burrows under skin into dermis; treat with ivermectin