antiparasitics

Lungs

· Dictyocaulus spp. (R, H)

· Prostostrongylus rufescens (S, G)

· Muellerius capillaris (S, G)

· Metastrongylus spp. (Sw)

· Filaroides spp. (D)

Kidneys

Stephanurus dentatus (Sw)

Urinary bladder

Capillaria spp. (D, F)

Stomach and Intestines

· Habronema spp. (H)

· Draschia spp. (H)

Skin

Onchocerca spp. (H)

Small intestines cestodes

Moniezia benedeni (R)

· Taenia spp. (R, D, F)

· Echinococcus granulosus (R is intermediate host, D)

· Dipylidium caninum (D, F)

· Anoplocephala perfoliata, A. magna (H)

· Paranoplocephala mamillana (H)

liver trematode

Fasciola hepatica (R)

deer liver

Fascioloides magna (R)

lung trematode

· Paragonimus kellicotti (D, F)

Abomasum in ruminants, stomach in monogastric animals

· Barberpole worm Haemonchus contortus, H. placei (R)

· Brown stomach worm Ostertagia ostertagi (R)

· Small stomach worm or hairworm Trichostrongylus axei (R, H)

· Red stomach worm Hyostrongylus rubidus (Sw)

· Large-mouth stomach worm Habronema muscae (H)

Intestines

· Small intestinal worms Cooperia punctata, C. oncophora, C. mcmasteri (R)

· Hookworms Bunostomum phlebotomum (R), Ancylostoma spp. (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, Triodontophorus spp. (R, H)

· Small strongyles Cyathostomum spp., Cylicocyclus spp., Cylicostephanus spp., Cylicodontophorus spp. (R)

· Whipworms Trichuris suis (Sw), Trichuris vulpis (D), Trichuris discolor (R)

· Threadworms Strongyloides ransomi (Sw), Strongyloides westeri (H), Strongyloides stercoralis (D), Strongyloides papillosus (R)

· Ascarids Parascaris equorum (H), Toxocara canis (D), Toxocara cati (F), Toxascaris leonina (D, F), Ascaris suum (Sw)

· Pinworms Oxyuris equi (H)

Anthelmintics

kill or expel worm parasites by acting on metabolic pathways that are present in the invading worm

but absent or significantly different in the animal host. Anthelmintics are further categorized as

antinematodal, anticestodal, or antitrematodal drugs. These drugs are given in a variety of ways

lable 15-3). The drug's solubility largely dictates the route of administration. Water-insoluble

nthelmintics are usually given orally (suspension, paste, granules), whereas more water soluble

pounds can be given orally as a solution, topically as a pour-on, or via injection. The drug

uce size also plays a role in the route of administration. Generally, smaller particles are more

ay absorbed from the Gl tract; larger particles (especially those that are insoluble) have mini-

mal absorption from the GI tract and therefore may be less toxic to the host.

Antinematodal

work against nematodes. Nematodes are elongated, non-segmented, cylin-

kical worms that come in a variety of sizes and shapes and infect a variety of organs and organ

eustems. The groups of antinematodal drugs are listed in Table 15-4. Some products contain drugs

from several of these groups to make them effective against more than one type of parasite.

Benzimidazoles (Think: -azole)

Antinematodal

· fenbendazole (Panacur) (also works on tapeworms and Giardia protozoa)

· oxibendazole (Anthelcide EQ Equine Wormer Paste)

· albendazole (Valbazen) (also works on tapeworms, flukes, and Giardia protozoa)

· oxfendazole (Benzelmin Paste for horses and Synanthic Suspension for

cattle [also works on tapeworms])

· febantel (Drontal Plus also contains pyrantel pamoate and praziquantel

Imidazothiazoles

Antinematodal levamisole (LevaMed) member of the imidazothiazole group of antinematodal drugs.

Levamisole stimulates the nematode's cholinergic nervous system, leading to paralysis of the

parasite. Because levamisole works on the adult nematode's nervous system, it is not ovicidal.

Levamisole causes expulsion of most nematodes within 24 hours, though the worms may be

passed alive. Levamisole comes in oral forms and is approved for use in cattle, sheep, and swine.

Levamisole is effective against ascarids, strongyles, whipworms, and hookworms. It also has

anti-inflammatory and immunostimulant properties. Levamisole toxicity in the host animal is due

mainly to its cholinergic effects, which may cause salivation, ataxia, and muscle tremors.

Tetrahydropyrimidines

Antinematodal

· pyrantel pamoate (Nemex and Strongid-T)

· pyrantel tartrate (Strongid-C)

· morantel tartrate (Rumatel)

include pyrantel pamoate, pyrantel tartrate, and morantel tart ..

These drugs are cholinergic agonists that mimic the action of acetylcholine This causes Inn

stimulation and then paralysis of the worm, causing it to release its grin on the intestinal

and be eliminated in the feces. These drugs come in tablet, paste, suspension (v

pleasant taste), and top dress forms and adverse effects are rare. They are approved for us s,

livestock, horses, dogs, and cats. This group is effective at treating ascarids, pinworms, strongyus

and hookworms. Particles in suspensions can settle to the bottom of the container: thereforerved

pensions should be shaken thoroughly prior to withdrawing a dose. There are many FDA

products containing pyrantel; trade names include Nemex and Strongid-T (pyrantel

Strongid-C (pyrantel tartrate), and Rumatel (morantel tartarate) (Figure 15-3A to C).

Piperazines

Antinematodal· piperazine (Pipa-Tabs and Hartz Advanced Care Once-a-Month Wormer for Puppies)

Macrocyclic lactones (Think: -ectin)

Antinematodal·

ivermectin (Heartgard, Heartgard Plus, Ivomec, Zimecterin Gold, EquiMax)

· eprinomectin (Eprinex , Eprizero, LongRange for cattle, Centragard for cats)

· selamectin (Revolution)

· doramectin (Dectomax)

· milbemycin oxine (Interceptor, Sentinel, MilbeGuard)

· moxidectin (ProHeart-6, ProHeart-12, Cydectin, Quest 2% Equine Oral Gel)

are a structurally related class of drugs that includes the avermectins

and milbemycins. Drugs with names ending in -ectin, such as ivermectin (the first avermectin),

doramectin, eprinomectin, and selamectin are typically avermectins.

The milbemycins are milbemycin and moxidectin. These drugs are approved for use in livestock, horses, dogs, and cats,and they may be administered orally, by injection, or topically.

Macrocyclic lactones bind to certain chloride channels in the nervous system of invertebrates causing paralysis and death of the parasite. Relatively low dosages, given orally and parenterally, work well against a wide range of internal and external parasites such as nematodes, bots, lice, mange mites, and grubs. They are not effective against cestodes and trematodes. The low dosage and inability to cross into the nervous system of most mammals make this class of drugs relatively safe in most instances. An exception is in collies, collie crosses, and collie-type dogs (Shetland Sheepdogs, Australian Shepherds) with the MDR1 mutation. Macrocyclic lactone drugs more easily enter the CNS and cause neurotoxicity in dogs that carry the MDR1 mutation resulting in depression, ataxia, and possibly death. Ivermectin has a higher risk of toxicity in susceptible dogs and in cats and kittens compared to the newer avermectin drugs.

Macrocyclic lactones are unusual as they are usually dose in micrograms per kilogram, while most drug dosages are in milligrams per kilogram.

Depsipeptides

Antinematodal. emodepside (Profender, which also contains praziquantel)

Pyrazine derivatives (Think: -antel)

Anticestodal praziquantel (droncit, profender (also contains emodepside)), interceptor plus (which also contains milbemycin, and quest plus (which also contains moxidectin))

Benzimidazoles (Think: -azole)

Anticestodal.albendazole (Valbazen), (also works on roundworms, flukes, and Giardia protozoa)

fenbendazole (panacur) (also works on roundworms and Giardia protozoa)

oxfendazole (Benzelmin Paste for horses and synanthic suspension for cattle (also works on roundworms))

Benzene sulfonamide

Antitrematodal. Clorsulon (ivomec plus and normectin plus which also contains ivermectin

Benzimidazoles

Antitrematodal. albendazole (valbazen) also works on roundworms, tapeworms, and Giardia protozoa)

Pyrazine derivative

Antitrematodal. Praziquantel (droncit, profender (which also contains emodepside), interceptor plus (which contains milbemycin, and quest plus (which also contains moxidectin)

Coccidiostats

Antiprotozoal. sulfadimethoxine (albon)

amprolium (corid)

decoquinate (deccox)

monensin (coban 60, rumensin)

robenidine (robenz Type A medicated article)

Nitroimidazoles

Antiprotozoal Metronidazole (flagyl)

Benzimidazoles

Antiprotozoal Fenbendazole (panacur) (also works on roundworms, tapeworms, and flukes.

albendazole (valbazen) (also works on roundworms, tapeworms, and flukes)

category of antinematodal drugs has excellent efficacy against nematode

infections. They are always administered orally, usually with a regimen that includes multiple

doses because their killing effects are slow. Benzimidazoles are believed to work by affecting

mitosis and meiosis in the parasite, which results in deformed, nonviable worms. Adverse effects

are rare with benzimidazoles but may include vomiting, diarrhea, and lethargy. Benzimidazoles

(Table 15-4) include the following:

Carbanilide derivative

Antiprotozoal imidocarb (imizol)

Folic acid antagonist

Antiprotozoal pyrimethamine (daraprim)

pyrimethamine plus sulfadiazine (rebalance)

Triazine

Antiprotozoal ponazuril (marquis)

diclazuril (protazil)

fenbendazole

is commonly used in small animals, food animals, horses, birds,

and reptiles. It has a wide spectrum of activity, including nematodes (hookworms and

whipworms) and the cestode Taenia pisiformis in small animals. Fenbendazole may also be

used to treat giardiasis. Although adverse effects are not common, vomiting and diarrhea

have been associated with this drug. It has been approved for use in lactating dairy animals.

An example is Panacur, which is found in a variety of formulations including granules, suspension and pastes

oxibendazole (anthelcide EQ Equine Wormer Paste)

a horse dewormer used to treat ascarids, large strongyles, small strongyles, threadworms, and pinworms. Adverse effects are4 rare

albendazole (valbazen)

primarily used in cattle to treat abomasal and intestinal

nematodes, flukes, and cestodes. It is not labeled for use in pregnant cows or in dairy

mws of breeding age. Albendazole also has a long withdrawal time, which limits it use.

nbendazole has a wide margin of safety in large animals, but there is a risk of bone marrow

toxicity causing leukopenia and thrombocytopenia in dogs and cats.

oxfendazole (benzelmin)

Paste for horses [not available in the United States but is made in other countriesl and Suspension for cattle) is available as an oral paste and solution that is used in horses against strongyles, ascarids, and pinworms and in cattle as

solution to treat lung worms, stomach worms, intestinal worms, and tape worms. When

used as labeled, adverse effects are rare.

thiabendazole is

not available in the United States for systemic treatment of parasitic

infestations, but it is included in some FDA-approved canine and feline otic preparations fo

its antifungal properties Chapter 18.

febantel (drontal plus)

probenzimidazole, a type of prodrug. Prodrugs must be

metabolized in the animal's body to the active form of the drug. Febantel is metabolized to

fenbendazole. Formulations of febantel usually combine it with another antiparasitic drug for a

broader spectrum of anti-endoparasite activity.

Organophosphates

used to treat and prevent ectoparasite infestations. Historically, organophosphates were also used for the treatment of endoparasites, but they have a narrow range of safety and so have been replaced with safer drugs for such use. Currently, OPs are used in products used to treat agricultural premises to decrease the presence of parasites, so veterinary professionals should be aware of the risk of OP toxicity in animals. OPs inhibit cholinesterase causing acetylcholine to remain active in the neuromuscular junction of the parasite and producing parasympathomimetic effects. They are neurotoxic to parasites and can cause some neurologic adverse effects in animals such as the development of tremors and hyperexcitability. Other adverse effects of OPs result from parasympathetic nervous system stimulation and produce SLUDDE (salivation, lacrimation, urination, defecation, dyspnea, and emesis).

ivermectin

found alone or in combination with other drugs in more than 50 FDA-approved

veterinary products such as Heartgard , Heartgard Plus, and Ivomec. The "Plus" products

contain other antiparasitic agents to broaden their spectrum of activity, Ivermectin is markete

for injection, for oral administration, as a paste, liquid, or feed additive, or as a pour-ion for

transdermal absorption. It is approved for use in horses, cattle, sheep, and swine.

moxidectin

the chemical used in ProHeart-6, the six-month injectable heartworm

preventive and ProHeart-12", the 12-month injectable heartworm preventive, which

also treat existing larval and adult hookworm (Ancylostoma caninum and Uncinaria

stenocephala) infections and in the monthly spot-on Coraxis for prevention of heartwuent

disease and control of hookworms, ascarids, and whipworms. It is also the active ingredie

in Cydectin in cattle and Quest 2% Equine Oral Gel. It is combined with imidocloprid in Advantage Mult" products, which are approved for the prevention of heartworm and

the treatment and control of intestinal worms and fleas in dogs, cats, and ferrets; sarcoptic

mange in dogs; and ear mites in cats. Imidocloprid provides the antiflea activity in these

aroducts. Adverse effects of moxidectin are the same as avermectins, with a low risk of CNS

signs such as stupor and seizures.

pyrethrins and pyrethroids

names end in -rin or -thrin. pyrethrins are natural plant products. pyrethroids are synthetic pyrethrins. Ex pyrethrin (mycodex shampoo, bio spot shampoo). Ex. permethrin and imidacloprid (K9 advantix). Usually safe except in cats (permethrin is metabolized poorly by

cats; therefore, permethrin must be used in a significantly lower

concentration (0.05-0.1% versus the 45-65% concentration used

in topical canine products) or avoided altogether in cats)

· Do not use forms labeled for dogs in cats

· Quick kill

· Adulticide, insecticide/miticide

· Often manufactured in combination products with other drugs such

as imidacloprid and pyriproxyfen

· Acts on the parasite's nerve cell membrane to disrupt the sodium

channel current, which delays repolarization and paralyzes the parasite

. May have limited residual effects

. In small animals used primarily for fleas and ticks in dogs

. In large animals used primarily for flies, lice, mites, mosquitoes,

ticks, and keds

· Commonly used in sprays, dips, foggers, pour-ons, insecticidal ear

tags, and premise sprays

insect growth regulators (IGR)

insect development inhibitors and juvenile hormone mimics. Methoprene (ovitrol and siphotrol). Pyriproxyfen. . Provide the flea with high levels of IGR, which mimics the insect's

juvenile hormone (JH). Fleas need low levels of JH to molt to the

next stage; high levels interrupt normal molting, so the insect stays in

the larval stage and eventually dies

· When combined with an adulticide (permethrin, fipronil, phenothrin,

etc.), it kills all stages of the parasite, making reinfestation unlikely

· Do not have adulticide activity by themselves

· Found in sprays and flea collars

chitin synthesis inhibitor

lufenuron (program), lufenuron and milbemycin (sentinel), Lufenuron and nitenpyram (capstar, flea mangement system, program flavor tabs. ·

• Chitin is an insect protein that gives strength and stiffness to its body;

• chitin synthesis inhibitors prevent proper formation of this protein

• · Lufenuron is an oral tablet given to dogs, a suspension or tablet given

• orally, or a SQ injection given to cats to protect against fleas for one month

• · Fleas that feed on blood containing lufenuron continue to lay eggs,

• but the eggs fail to develop normally

• · Does not kill adult fleas

neonicotinoid

nitenpyram (capstar capguard), nitenpyram and lufenuron (capstar flea management system, program flavor tabs) Binds and inhibits nicotinic acetylcholine receptors. ex dinotefuran and pyriproxyfen (vecra for cats, vectra for cats and kittens)

· Tablet that kills adult fleas within 30 minutes (nitenpyram is not effective against eggs or immature forms if used alone)

· Can safely give a dose as often as once per day

· Can use on puppies and kittens older than four weeks and weighing more than 2 pounds

Third-generation neonicotinoid (dinotefuran) and IGR (pyriproxyfen) that

can be used on kittens older than eight weeks of age

. Once-monthly topical spot-on that kills adult fleas within six hours

and controls the development of all flea stages

isoxazoline

fluralaner (bravecto), afoxolaner (nexgard), sarolaner (simparica), lotilaner (credelio)

. Binds to GABA and inhibits chloride channels in nerve and muscle cells, which blocks nerve transmission causing paralysis and death in insects and ticks

. Kills adult fleas and treats and controls ticks (black-legged, American dog, and brown dog ticks are controlled for 12 weeks in dogs and puppies over 6 months of age and lone star ticks are controlled for 8 weeks in dogs and puppies over 6 months of age)

. Based on postmarketing information, the FDA issued a warning that this class of drugs may produce muscle tremors, ataxia, and seizures in some animals

imidacloprid

imidacloprid (advantage),

• Acts as an insect neurotoxin by binding to the niconyl receptor (inhibits cholinergic activity of the parasite)

• . Marketed for dogs and cats

• . Applied topically at the back of the neck and is not absorbed into the blood

• · Kills adult fleas on contact

• · Has four-week residual effect

imidacloprid and permethrin (K9 advantix)

• · Works synergistically to rapidly paralyze and kill parasites

• · Kills fleas (adult and larval stages) and kills and repels mosquitoes, and

• ticks (deer, American dog, brown dog, lone star)

• · For use on dogs and puppies seven weeks of age or older

• . Not for use on cats

imidacloprid and moxidectin (advantage multi for dogs, advantage multi for cats

• · Kills adult fleas, adult and immature hookworms, adult

• roundworms, and adult whipworms, and prevents heartworm disease in dogs over seven weeks of age

• · Kills adult fleas, ear mites, adult and immature hookworms, and

• adult roundworms, and prevents heartworm disease in cats over nine weeks of age

• · Once-monthly topical solution

phenylpyrazole

fipronil (frontline), fipronil with methoprene (frontline plus)

• Interferes with chloride channels of insects, which overstimulates their nervous system causing death of adult fleas, ticks, and chewing lice (Figure 15-13)

• · Methoprene is an insect growth regulator, which makes the combination product effective against flea eggs and flea larvae

• · Is applied topically but is not absorbed into the blood

• . Collects in the oils of the skin and hair follicles and continues to be released over time resulting in residual activity (spread over the body in 24 hours) (see Figure 15-12)

• . Kills newly emerged adult fleas before they can lay eggs

• · Residual activity even after bathing

• · Labeled for treatment of fleas, ticks, and chewing lice when used monthly and control of sarcoptic mange with repeated treatment

• . Not for use in puppies or kittens less than eight weeks of age

macrocyclic lactones

selamectin (revolution)

• Interferes with postsynaptic stimulation of the muscle fiber in arthropods or neurons in nematodes causing paralysis and death. In cats, works on adult fleas and eggs, heartworms, ear mites, hookworm, and roundworms

• . In dogs, works on adult fleas and eggs, heartworms, ear mites, sarcoptic mange, and American dog tick

ivermectin (ivomec, equel paste, equimax, eqvalan)

• Injectable or oral solution used for some ectoparasites and endoparasites

• · Potentiates insect's GABA neural and neuromuscular transmission

• · Blood-feeding ectoparasites (such as fleas, mites, and lice) are killed more effectively by ivermectin than superficial, nonblood feeders (like Cheyletiella spp.)

• . Effective against the following ectoparasites: bots, grubs, lice, and mites (including demodex)

doramectin (dectomax)

• Injectable and topical solution used for some ectoparasites and endoparasites

• . Used as a pour-on in cattle for biting lice and mites; used in dogs and cats for generalized demodicosis

eprinomectin (ivomec, eprinex)

• . Topical pour-on for beef and dairy cattle

• · Used to treat and control GI nematodes and ectoparasites (cattle grubs, lice, mange mites, and horn flies), and ear mites (Psorpotes cuniculi) in rabbits

• . Increases permeability of the parasite's cell membrane to chloride ions resulting in paralysis and death of the parasite.

• · No milk or meat withdrawal

acetylcholine receptor agonist

spinosad (comfortis)

· Once-a-month oral chewable flea protection for treatment and

prevention of fleas in dogs 14 weeks of age or older

. Causes involuntary muscle contractions in fleas that leads to

seizures, paralysis, and death

. Fast acting and long acting

. Flea death begins in 30 minutes and is complete in four hours

. May cause systemic side effects such as vomiting, anorexia,

lethargy, or diarrhea

. Administration with food increases its effectiveness

formamidine

amitraz (preventic collar)

Alpha-2 adrenergic agonist and monoamine oxidase inhibitor that

causes excess adrenergic activity in the parasite's nervous system

. Animals may show sedation for 24-72 hours following treatment

· Toxic to cats and rabbits (although has been used on cats in diluted

form)

sulfurated lime solution

lime sulfur (limeplus dip generic brands)

Provídes antimicrobial and antiparasitic activity through the

formation of pentathionic acid and hydrogen sulfide after application

· Used in the treatment of sarcoptic and notoedric mange, cheyletiellosis,

chiggers, fur mites, and lice; also demodicosis in cats

· Also effective for the treatment of ringworm

· May stain light-colored animals

· Used as a rinse or dip following dilution

repellent

butoxypolypropylene glycol (vip fly repellent ointment)

· Used to repel mosquitoes, flies, and gnats

. May be used in combination with pyrethrins and pyrethroids

· Include sprays, ear tags, and topical forms for ear tips

d limonene

d limonene (adams d limonene flea and tick shampoo)

Extract of citrus peel that has some insecticidal activity

· Provides quick kill

· No residual

· Pleasant smell

antitrematodal

used in the treatment of trematodes, the flat, leaf-shaped helminths whose

bodies lack segmentation (Table 15-4). Trematodes are commonly referred to by the area they infect

e.g., the liver trematode commonly called the liver fluke) (Figure 15-5A). Trematodes have interme-

ulate hosts, the first of which is almost always a snail. Snails are found in wet, rainy environments;

environmental management is important in preventing recurrent trematode infections.

clorsulon,

benzene sulfonamide, inhibits the trematode's enzyme systems used in energy

production and robs the trematode of its energy. Clorsulon is effective against the adult and immature

forms of the liver trematode. Fasciola hepatica, in cattle. Clorsulon is available in combination with ivermectin in multiple injectable products including lvomec" Plus and Normectin Plus. Adverse effects are not common but include swelling at the injection site. These products have weeks-long withdrawal times, so they are not used in female dairy cattle of breeding age

albendazole (valbazen)

benzimidazole, is effective against Fasciola hepatica adults in cattle. It also

is a broad-spectrum anthelmintic (it also works on cestodes and nematodes). Milk withdrawal times for

albendazole have not been established; therefore, it is not approved for use in lactating animals.

the anticestodal drug praziquantel may also be used to treat lung trematodes in dogs and cats.

hwtx

Adult heartworms may develop in the right ventricle, right atrium, or vena cava (referred to as

caval syndrome when the vena cavae are involved) because of improper or no use of preventives.

lreatment of heartworm disease is far more expensive, complex, and risky than the safe and sim-

ple administration of heartworm preventive drugs.

Prior to the administration of a heartworm adulticide (antiparasitic drug used to kill adult helminths),

Lis recommended that a heartworm-positive dog be treated for up to two months with a macrocyclic

actone (ivermectin-type) drug and the tetracycline-class antibiotic drug doxycycline. This combina-

n of drugs eliminates heartworm larvae and Wohlbachia species bacteria that often infect heart-

em larvae. By eliminating the larvae and bacteria prior to treatment with a heartworm adulticide.

ne risk of complications (including death) during adulticide treatment is reduced.

melarsomine (immiticide, diroban)

arsenical drug given by deep IM injection to kill adult heartworms (Figure 15-9C). The drug is given in the epaxial muscles on either side of the vertebral column. in the area between the L3 and L5 vertebrae. Because it causes substantial tissue irritation, melarsomine is administered with a long (1.5 inches), small-gauge needle (22- or

Mo ge) to place it deep in the muscle and minimize leakage of drug from the injection site.

dra somine is not recommended for use in animals with large numbers of heartworms, because

Bes eatment of such animals results in obstruction of the right side of the heart, the large ves-

ad and the lungs with large numbers of dead worms. Coughing, gagging, and lethargy are

Dose effects of this drug along with the risk of hepatotoxicity and pulmonary inflammation.

ogs should be kept inactive after receiving adulticide treatment.

Imidocarb dipropionate (imizol)

FDA approved for the treatment of dogs and horses infected

with Babesia sp., a family of blood parasites transmitted by ticks; it may also be used in cats.

Babesiosis can be treated by intramuscular injection with imidocarb, which appears to have a

cholinergic effect on the protozoan. Adverse effects of imidocarb include cholinergic effects such

as salivation, dyspnea, and restlessness, pain at the injection site, and vomiting. Using tick pre-

vention can reduce the occurrence of infections with Babesia sp.

Equine protozoal myeloencephalitis (EPM) is a neurological disease in horses that is caused by the

protozoan Sarcocystis neurona. The immature forms of this protozoan are ingested by the horse anu

then they enter the bloodstream, replicate, and migrate to the central nervous system, where ther

cause clinical signs that, if untreated, progress from ataxia to recumbency and death.

pyrimethamine sulfate,

approved for the treatment of EPM. marketed in a combined formulation with sulfadiazine

(ReBalance) as an oral suspension for the treatment of EPM in horses. Pyrimethamine

works by inhibiting an enzyme that converts one form of folic acid used for metabolism.

parasites to an inactive form of folic acid. Myelosuppression (suppression of cell producto

by the bone marrow) has been associated with the use of pyrimethamine in horses. Tne

drug may also be used extra-label to treat protozoal infections in dogs and cats.

ponazuril (marquis)

approved for the treatment of EPM. extra-label to treat protozoal infections in dogs and cats.

· ponazuril (Marquise) is a triazine antiprotozoal drug that targets metabolic processes sped

to some protozoa. Ponazuril may also be used in dogs and cats to treat toxoplasmosis and

coccidiosis. Because the drug targets pathways specific to protozoa, adverse effects are rare.

diclazuril (protazil)

approved for the treatment of EPM. prodrug that is metabolized to ponazuril after oral administration to horses.