SHB Category: J, Parasites Flashcards
Pages 381-410 Complete Deck
What is another name for internal parasites?
Endoparasites
What type of segmentation does a nematode have?
None
What is another name for ectoparasites?
External parasites
What is another name for endoparasites?
Internal parasites
Which 3 species of strongyles are the most damaging to the horse?
Strongylus vulgaris, strongylus edentatus, and strongylus equinus
What is another name for external parasites?
Ectoparasites
What is the genus of the bot?
Gasterophilus
Which adult parasite resembles a honey bee?
Bot fly
What is a parasite?
Small organism that lives on or in and at the expense of a larger organism called a host
Define an ectoparasite.
Parasites that attack the skin and body openings of the horse
What are nits?
Lice or bot eggs
What is another name for nematodes?
Roundworms
Name the 2 general types of parasites.
Internal (endoparasites), and external (ectoparasites)
What is another name for a nematode?
Roundrowm
Which insect does the horse bot fly resemble?
Honey bee
Which sex of the horse fly bites the horse?
Female
What is the most common cause of colic and undernourished horses?
Internal parasites
What is the very large (5-22 inches) yellowish-white nematode parasite of the small intestine?
Ascarids
Describe a nematode.
Round worm with slender, unsegmented cylindrical bodies that taper towards each end
What is the more common term for Parascaris Equorum?
Ascarids
What is the more common term for Gasterophilus Intestinalis?
Common bot
Which parasite spends their entire life from egg to adult clinging to the hairs of a horse?
Lice
What are the 2 principal undesirable effects of oxyuris equi infections?
Disfigurement and discomfort
Describe the parascaris equorum.
Large (5-15 inches) yellowish-white nematode of the small intestine
How many eggs does the pinworm lay?
8000 to 60,000
Describe an ascarid.
Very large (5-15 inches) yellowish-white nematode of the small intestine
Musca Autumnalis is the species of which common parasite?
Face flies
Strongylus vulgaris, strongylus edentatus, and strongylus equinus are usually found where and can cause what condition?
Blood vessels of the large intestine and can cause anemia or possibly an embolism
What is the infective stage of a parasite?
The stage which is adapted to gaining access and taking up residence in the host
Stomach worms can cause severe itching and production of exuberant granulation tissue. What is the common name for the tissue that is produced?
Proud flesh
What is the third stage molt of all nematodes?
Ecolysis (casting of old larval skin)
What are the common terms for external and internal parasites?
Ectoparasites (external) and Endoparasites (internal)
How many eggs are laid by a female louse?
20-30 eggs at intervals of 1 1/2 days
Which parasite’s second stage larvae is encased in a sticky and protective shell and can remain alive and stuck to a surface for years?
Ascarids
How long is an ascarid?
5-15 inches
How many species of bot flies are there in North America
3
What does the adult bot fly feed on?
Nothing, they only have vestigial mouth parts and cannot eat
How many species of strongyles is the horse a host to?
54
All nematodes undergo how many molts?
4
Name 3 parasites that can cause tail rubbing.
Pinworms, mites, and lice
Which type of parasite is Chorioptes equi?
Mite (this one causes tail mange)
Severe louse infestations are rarely observed in pastured horses during what season of the year?
Warmer months (summer) it is most common in late fall
What is a form of dermatitis characterized by the formation of crusts or scabs, intense itching, and is caused by mites?
Mange
Name 3 causes of pruritus ani.
Pinworms, mites, and lice
What causes persistent, disfiguring, and intensely itching skin lesions called summer sores?
Stomach worms (habronema)
What stage of life would the large strongyles live in water films of vegetation, stable walls, managers, and etc?
Third stage larva
Which internal parasite can cause chronic conjunctivitis?
Stomach worms
What is a slender, unsegmented cylindrical parasite that tapers towards each end?
Nematodes (roundworm)
Which type of parasite has a tendency to group together near the ileo-cecal junction, may cause chronic diarrhea and can cause instersusception (telescoping of the intestines)?
Tape worm
Which internal parasite’s eggs are usually not found in the manure but are usually adhered to the skin of the anus?
Pinworms
Which adult parasite of the horse has no mouth parts, can not eat anything and must rely on energy it stored while a parasitic larvae in the stomach?
Bot fly (must say fly)
How many species belong to the family, Strongylidae?
54
Of the 3 species of bots, which one is the most common?
Gasterophilus intestinalis
Which parasite of the horse is closely related to the common house fly?
Face fly
What type of endoparasite can cause a foal to have a dull hair coat, dry skin, and distended abdomen?
Ascarids
Which is the only species of common bots to lay black eggs?
Gasterophilus hemorrhoidalis
How large is parascaris equorum?
5-15 inches long
What is another name for a roundworm?
Nematode
Which parasite is slender, the tails terminate into a point, and they cause disfigurement and discomfort to the horse?
Pinworm
Which stage of the Strongylus vulgaris’ life cycle does the most damage to the host?
Fourth stage larvae
Small strongyles’ larvae are the most numerous in fecal cultures, which species of strongyles has the next highest numbers?
Strongylus vulgaris
Which parasite is at a maximum level in the early weeks of a foal’s life but finally disappears at approximately 5 months of age?
Strongyloides westeri
What is the only nematode that does not have a separate male and female parasitic form?
Strongyloides westeri
The horse is host to approximately 54 species of this worm family, name it.
Strongyles
Which species of pinworm is the largest?
Oxyuris equi
When should the treatment for bots be scheduled?
From mid to late summer and after a killing frost
What are the large roundworms that primarily affect foals and young growing horses?
Ascarids (parascaris equorum)
What are the 2 basic methods of internal parasite reduction?
Management and chemical control
Adult horse flies are the intermediate host to which parasite?
Stomach worm (habronema)
A large population of bloodsucking stable flies may cause several problems, name 2.
Severe dermatitis (skin problems), possible infections, secondary affects of blood loss, fractured leg bones from stomping
How long is the life cycle of a mosquito?
10-14 days
Name 2 methods of purge deworming.
Paste, stomach tube and those using feed as a carrier for the compound
Many veterinarians recommend deworming foals and weanlings how often?
Every 30-60 days for first year of life
Lone Star, Rocky Mountain, American dog. Tropical and Spinose are all different types of what?
Ticks
Which parasite can cause erosion on the tongue and gums of the horse?
Bot larvae
What type of test is used by your vet to determine the number and type of parasites found in your horse?
Fecal examination
Threadworms (strongyloides westeri) infections originate from what 2 sources in the foal’s environment?
By ingesting larvae in dam’s milk or by larvae present in bedding by penetrating foal’s skin
Which intestinal parasite is not affected by the ‘continuous’ deworming program?
Bots
What is the most common physical form of administering anti-parasitic compounds to horses?
Paste
Which fly is so annoying to some horses that they may lose weight because they spend more time fighting this fly than grazing?
Bot fly
Infections of strongyloides westeri are most common in young foals of what ages?
From 4-47 days old
What is the main problem caused by threadworms?
Diarrhea
After being swallowed by the horse, where do the bot larvae attach themselves?
Wall of the horse’s stomach
Organophosphates are used primarily to kill which parasite?
Bots
Which part of the horse’s digestive system is affected by strongyles, pinworms, and tapeworms?
Large intestine
What term describes insects that carry disease producing organisms?
Insect vector (vector)
Name the 3 most important strongyles as far as doing the most damage.
Strongylus vulgaris, Strongylus edentatus, strongylus equinus
What is the scientific name for threadworms?
Strongyloides westeri
What is the scientific name for the red bloodworms that infect horses?
Strongyles
What is the life cycle of a fly?
Egg, larvae, pupa and adult
What is the scientific name for the common horse bot fly?
Gasterophilus instestinalis
Name the parasite that depends on wet saliva from the horse’s mouth in order to hatch and become infective.
Bot
Name the parasite that affects foals through its dams milk by penetrating the foal’s skin.
Strongyloides westeri (threadworms)
Approximately how much money is spent per year on pest control?
$270 million
Which adult parasite may reach a length of 5-22 inches?
Ascarids (parascaris equorum)
Name the parasite responsible for the most damage to the horse’s lungs and liver.
Ascarid larvae (parascaris equorum)
How long does it take to complete the life cycle of a house fly?
1-2 weeks
How long does it take for a nymph to reach maturity?
3-4 weeks
How should cattle grubs be removed from horses?
Surgically by a vet
Doubling the normal dose of pyrantel pamoate is an effective treatment for which parasite?
Tape worms
Oribatid mites are an intermediate host for which parasite?
Tape worms
What is the primary objective to a successful parasite control program?
Interruption of the parasite’s life cycle
During which season are lice more of a problem for horses?
During winter
How many distinct species of small strongyles infect the large intestine of the horse?
about 40
How long is the life cycle of the threadworm?
Less than 2 weeks
Which of the strongyles is the most damaging to the horse?
Strongylus vulgaris
Of the Big 3 of the strongles family, which one is the most important and most destructive?
Strongylus vulgaris
What 2 things are necessary for bot eggs to hatch?
Friction and moisture
What is the poisonous chemical found in the secretion of the blister beetle?
Cantharid
Which of the 2 general types of strongyles is the most numerous in the naturally infected horse?
Small strongyles
There is strong evidence that the so-called foal heat diarrhea is not related to any alteration the the chemical composition of the mare’s milk but is in fact caused by what?
INfections with strongloides westeri (threadworms)
Strongyles are divided into 2 major groups, what are they?
Large and small strongyles
In which organ does the third stage larva of strongylus endentatus and strongylus equinus molt into their fourth stage larva?
In the liver
Which 2 parasites serve as an intermediate host for the stomach worm?
House flies and stable flies
Name the parasite associated with summer sores.
Stomach worm
What is the vector for lyme disease?
Ticks
What is the foundation of any fly control program?
Good sanitation
What would be an acceptable fecal egg count in a few horses that occupy a relatively large pasture?
500 eggs per gram or lower
The fourth stage larvae of which parasite will migrate to the anterior mesenteric artery where they cause inflammation?
Strongyles
What would be an acceptable fecal egg count in large amounts of horses confined to a small paddock?
100 eggs per gram or lower
Which type of parasite can cause malnutrition, perforation of the bowel wall, and fatal peritonitis?
Ascarids
Which type of parasite has parasitic females that develop from unfertilized eggs and there are no parasitic males?
Strongyloides westeri (threadworms)
In what 2 areas are adult pinworms most commonly found?
Colon and rectum
Ascarids eggs will start to appear in the manure of foals at what age?
10-13 weeks
What is the most successful way to control parasites?
Interrupt the parasite’s life cycle or have a good deworming program
How many eggs will the adult female ascarid lay per day?
Up to 200,000
Strongyles occur in horses of all ages except one, name this age.
Neonatal foals
What is the incubation time for bot eggs and what stimulates them to hatch?
Incubation is 1-5 days, hatch when horse licks them
How many eggs does the strongyle female lay per day?
Several thousand eggs per day
How long is the average life cycle of the strongylus vulgaris?
6-7 months
What type of parasite is the trichostronglus axei?
Stomach worm
How long is the average life cycle of strongylus equinus and edentatus?
8-11 months
What percentage of strongle eggs in a naturally infected horse are produced by small strongyles?
75-100%
Which of the major internal parasites of the horse has no migratory state after being ingested?
Pinworms
What is an anastomosis?
Network of interconnections in the intestinal arterial tree
What 3 endoparasites utilize only the horse as a host?
Strongles (blood worms), Ascarids (intestinal worms), Stomach bots
What blood vessel is the most converged on in the migration route of the strongyles in every horse?
Cranial mesenteric artery
Name the parasite that is responsible for foal heat diarrhea, that in fact has nothing to do with the first postparturient heat of its dam.
Strongyloides westeri
Which is the smallest of the Big 3 strongyle nematodes?
Strongylus vulgaris
The horse’s arterial evolution in feeding blood to its intestines is an adaptation from attacks of what form?
Strongylus vulgaris
Which external parasite can cause anemia if enough are on the horse?
Bloodsucking lice
Which parasite causes an itchy anus?
Pinworms
What are the 2 types of lice that infect horses?
Bloodsucking (haematopinus asini) and biting (damalinia equi)
How do horses become infected with tapeworms?
By ingesting free-living mites infected with tapeworm larvae
What are the 2 species of pinworms that infect horses?
Probstmayria vivipara and oxyuris equi
What do we call lice eggs?
Nits
Why are foals particularly susceptible to threadworm infections?
They can ingest larvae from their dam’s milk
How many species of tapeworms are there?
3
How long does the bot larvae stay in the stomach of a horse?
9 months
Approximately how long after the administration of an effective anthelmintic drug is it before strongyle eggs reappear?
6-8 weeks
Name 2 parasites that utilize horses and other animals as hosts.
Horse flies, mosquitos, face flies, trichostrongylus axei, certain ticks
What are 2 of the favorite breeding sites for the house fly?
Manure and decaying organic matter
Where do the first stage larvae of Gasterophilus intestinalis hatch?
On the outside of the horse-usually on the hairs of the forelegs
Which parasite is a distant cousin to the spider?
Mange mites
Why is a knowledge of the life cycles of parasites and the nature and habits of their infective stage important?
To understand the parasite control programs
What is pruritus ani?
Itching of the anus
In what part of the horse do ascarid larvae do the most damage?
Liver and lungs
How many species of pinworms are there that infect the horse?
2
How often should a horse be dewormed?
6 times per year (every 2 months)
Which female parasite travels through the horse’s intestines to lay its eggs on the horse’s anus?
Pinworm
What are the 8-legged nuisances that live on or in the epidermis and cause a form of dermatitis?
Mange mites
Why must adult bot flies use stored energy to mate and lay their eggs?
They have no mouthparts with which to eat anything
Where do the larvae of ascarids do the most damage?
Liver and lungs
Which stage of development of the bot is found in the stomach?
Larvae
What are anthelmintics?
Deworming remedies
Doubling the does of pyrimidines has been effective in controlling which internal parasite?
Tape worm
What are the larvae of Gasterophilus called?
Bots
Name 2 general types of internal parasites that are usually found in the intestines.
Ascarids and strongyles
Mature tape worms first occur in what 2 ages of horses?
Weanlings and yearlings
How are lice usually transmitted?
By direct contact with other lice infected horses
Where does the Gasterophilus intestinalis deposit its eggs?
On the hairs of the forelimbs and shoulders of the horse
What are the 3 species of bots that deposit their eggs on the hair of the horse?
Gasterophilus intestinalis, Gasterophilus nasalis, Gasterophilus hemorrhoidalis
What do face flies feed on?
Secretions of eyes, nostrils, and mouth of horse
What is the purpose of screening or dragging your pastures to spread out manure piles?
To reduce parasites
Mange mites are distant cousins to what other insect?
Spiders
How many legs do mange mites have?
8
What is the purpose of anthelmintic medications?
Dewormers used to prevent environmental contamination by reducing adults that produce eggs
Where do face flies lay their eggs?
Cow manure
What is the primary cause of Foal Heat Diarrhea?
Parasite, strongyloides westeri (threadworms)
What causes summer sores on horses?
Stomach worms
Name 5 breeds of flies that annoy the horse.
House, bot, horse, stable, and horn
Name the external parasite of the horse that is a distant cousin to the spider and that causes mange.
Mange mites
Mosquitos commonly feed on horses at what time of day?
At dusk
Tapeworms infect horses through what intermediary host?
Mites
What are 4 criteria for successful fly control?
Eliminate breeding material, control moisture, mechanical control, use of insecticides
How do horses get tapeworms?
By ingesting free-living mites in pasture
Name 2 places where stomach worms are found.
Stomach and injured skin (summer sores)
Name the deworming drug that requires the most caution in use due to its toxicity.
Organophosphates
What is the scientific name for the small, almost invisible pinworm?
Probstmyria vivipara
Vesicular stomatitis affects what part of the horse?
Mouth
Name 3 practices of a good internal parasite control program.
Deworm every 2 months, rotate deworming drugs, worm all horses on premises, take fecal examinations, frequent removal of manure, rotation of pastures
Which type of insecticide spray used in the control of lice is preferred?
Wettable powders because they can be more sensitive to skin burns
What are cyathostomes?
Small strongyles
Where does the ascarid larvae migrate to, after they burrow into the wall of the horse’s intestines?
Into the veins of the circulatory system
After being swallowed by the horse, where do bot larvae attach themselves?
To the stomach walls
What blood vessel is damaged by Strongylus vulgaris?
Anterior mesenteric artery
The I Dammini tick species is a primary vector that causes which disease?
Lyme disease
At what time of day do mosquitos commonly feed on horses?
At dusk
What species of parasite can cause a weakening and bulging of the arterial wall, known as an aneurysm?
Strongylus vulgaris
Which parasite’s eggs can survive freezing winters but are killed by hot, dry summer conditions?
Strongyles
What is the most dangerous class of dewormers?
Organophosphates
Name the least safe dewormer in regards to toxicosis in horses.
Organophosphates
What is the recommended age for a foal to be dewormed for strongyles and ascarids?
At 60 days of age (2 months)
The larvae of which internal parasite often appears in the mare’s milk soon after foaling and is commonly the first parasite encountered by the foal?
Threadworms (strongyloides westeri)
What is the only parasite that infects both horses and ruminants?
Trichostrongylus axei
What is the largest class of dewormers?
Benzimidazoles
Which parasite is the most significant and the most common of all equine internal parasites?
Strongyles (blood worms)
What dewormer has shown the most parasite resistance in horses?
Benzimidazoles
What is an ‘obligate parasite’?
Parasite that cannot survive away from the host animal
Name 2 internal parasites that contaminate their stalls with sticky eggs.
Ascarids and pinworms
Name 2 areas on the horse’s body that are affected by the psoroptic mange mites.
Beneath forelock, beneath mane, at base of tail
All nematodes undergo a series of 4 molts, name them.
Lethargus (resting stage), metamorphosis (restructuring), ecdysis (casting of old larval skin), and emergence of new worm
Describe what is happening during each of the following molts of the nematode, lethargus, metamorphosis, ecdysis
Lethargus-resting stage, metamorphosis-restructuring, ecdysis-casting of old larval skin
What is the scientific names for the 3 bot flies and where does each on lay their eggs?
Gasterophilus nasalis-eggs on hair in the space between the jawbones, Gasterophilus intestinalis-eggs on the horse’s forelimbs and shoulders, Gasterophilus hemorrhoidalis-eggs on short hairs around horse’s lips
