Midterm Critical Thinking Questions

The magnification of the ocular (eyepiece) on a microscope is 10x. T/F

True

The magnification powers of each of the objectives on the microscope is 5x, 10x, 20x & 100x. T/F

False, there is 4x (scanning), 10x (low power), 40x (high power), and 100x (oil immersion).

An efficient vet tech should read their slides under the microscope the same way every time. T/F

True, as long as the slides were made correctly.

Free-living nematodes are pseudoparasites. T/F

True

Tree pollen granules may be confused with the eggs of Toxocara species. T/F

True, due to their shape and size being like each other.

Sheather's solution and zinc sulfate are the 2 different types of fecal flotation solutions that we use in lab. T/F

False, we do not use Sheather's solution in our lab. We use Sodium nitrate & zinc sulfate.

Timing is not important when performing a fecal flotation.

False, it is important. The eggs won't be able to float and attach to the cover slip if its under 15 minutes, and too much time means crystals could form on the coverslip and the slide would be hard to read.

When collecting a pooled sample for a fecal exam, the specific animal of origin is known. T/F

False, it won't be known, but it will be adequate since all those animals will be tested. Several samples are taken from the same pen, as well, in a pooled sample.

The centrifugal sedimentation technique concentrates eggs at the bottom of a centrifuge tube. T/F

True

If a parasite is zoonotic, it cannot be transmitted from animals to humans.

False, it can. Through bites, contaminated food or water that has animal feces, and just direct contact.

The scientific name of an organism

Genus species

A definitive host harbors ______ of a parasite

adult stage

A nematode may or may not use an ____________________ as a means of transmission to their definitive host; therefore, life cycles can be either ______________ with the use of an intermediate host or _____________ with no intermediate host.

intermediate host

indirect

direct

T. canis, T. cati & T. leonina are commonly known as ___________ of dogs & cats.

roundworms

Adult ascarids (roundworms of dogs & cats) are found in the _______________.

small intestines

T. canis & T. cati can be characterized by a deeply pigmented center, which is typically _______________ in color, & a thick-walled rough pitted outer shell.

dark brown

T. ____ is smaller in diameter than T. canis.

cati

Toxocara species are ____________!

zoonotic

Ancylostoma canis is commonly known as canine hookworm. T/F

False, it is spelled out as Ancylostoma caninum.

Trichuris vulpis, commonly known as canine whipworm, can be confused with E. aerophilus, a lungworm of dogs, cats & foxes. T/F

True

T. vulpis eggs are trichuroid or football-shaped, thick & dark brown with a symmetric shell & smooth rounded ends. T/F

False, their color is yellow brown, the smooth rounded ends = polar plugs, which are an identifying characteristic of T. vulpis; this is the only parasite egg we study that has polar plugs.

When adult hookworms attach to the mucosa of the large intestine & suck blood, they secrete an anticoagulant which can essentially cause anemia as one of the clinical signs, especially in puppies. T/F

False, they are attached to the small intestine

Hookworms are zoonotic, leading to a condition in humans called Cutaneous Larva Migrans. T/F

True

The eggs of Ancylostoma caninum contain a(an) _____________________.

8 to 16 cell morula

Tapeworms are in the phylum Platyhelminthes & the class  __________.

Cestodes

Eucestoda or true tapeworms absorb nutrients through their _________.

body walls

If a tapeworm has anchor-like, backward facing hooks, it is armed because it possesses a ____________.

rostellum

Tapeworms are dorsoventrally flattened and contain segments known as ____________.

proglottids

A dog or cat becomes infected with the tapeworm, _________________________ (scientific name), by ingesting the flea intermediate host.

Dipylidium caninum

.  Three intermediate hosts for Taenia species include _________ , _________ , and _________________.

rodents, rabbits, and small ruminants

The tapeworm, _____________________ (scientific name), is the hydatid cyst tapeworm of dogs.

Echinococcus granulosus

The intermediate host for Anoplocephala species is the ________________ which contains the cysticercoid larval stage.

oribatid grain mite

Moniezia species are found in the small intestines of _____________, their definitive host.

ruminants

. Diphyllobothrium latum, a pseudotapeworm, is commonly known as the _________________ tapeworm.

broad fish

The definitive host of Taenia pisiformis, Taenia hydatigena & Taenia ovis is the ____.

dog

Class for flukes

Trematoda

Subclass Digenea

Endoparasites of Wild & Domesticated Animals & Humans

Life Cycle of Digentic Flukes

Complex indirect

1st Intermediate Host of All Digenetic Flukes

snail

Free-Living Larval Stage

Cercariae

Dicrocoelium dendriticum

lancet fluke of sheep, goats, and cattle

Fasciola hepatica

liver fluke of cattle, sheep, and other ruminants

Platynosomum fastosum

lizard poisoning fluke of cats

Nanophyetus salmincola

salmon poisoning fluke of dogs

Paragonimus kellicotti

lung fluke of cats and dogs

Dicrocoelium dendriticum, the lancet fluke, is unusual because it uses two __________________________________________.

Intermediate hosts from only dry environments (1st/land snail; 2nd/ants)

Cystoisospora sp. can cause coccidiosis in young or immunosuppressed animals. T/F

true, in young puppies and kittens

Giardia sp. can be fatal to a developing human fetus. T/F

False, it is Toxoplasma gondii.

The oocysts of Eimeria sp. may or may not have a micropyle or cap-like opening at one end and may contain 1 to 4 nuclei. T/F

True, it depends on the species

Giardia is the cause of "Beaver Fever." T/F

True, because beavers are often reservoir hosts - the cysts passed in their feces can survive for months in cold water.

. Heavy burdens of Oxyuris equi can cause GI stasis.  T/F

False, it is Parascaris equorum.

The protozoan commonly called coccidia is from the phylum __________________.

Apicomplexa

How should a fecal sample be preserved if it can't be examined when fresh?

Preserved in a cool, dark place (cooler) or a clean, sealed container in the fridge away from food

They should be tested within 24 hours and never frozen

Describe the collection of a small animal fecal sample. How much is needed?

2 grams needed

Owner should witness animal defecating, observe for straining, blood, etc.

Collect the feces immediately and place sample in baggy/ sealed container, then label: owner & pet's name, date, and time

Describe the collection of a large animal fecal sample. What is a "pooled" sample?

Collect feces directly from the rectum or watch for defecation and collect immediately, then labeled properly

For grouped animals, use a pooled sample (several samples taken from the same pen without knowing the specific animal of origin)

Why is a pooled sample adequate?

If 1 animal is positive, likely many/all of them are. So, if the fecal is positive, all the animals will be treated.

What are 3 practices that should be followed when preforming fecal examinations?

Wearing gloves, safety glasses, scrubtop, and closed toe shoes

Always wash hands before and after handling/testing feces

No food or drink near samples/testing area

List 6 gross characteristics of a fecal sample that should be noted in the record

Consistency (hard, soft, watery)

Color

Blood (fresh/ frank red vs dark/tarry)

Mucus

Age of feces (dry or fresh)

Parasites

Why is a fresh sample necessary?

Protozoan parasites die & disappear within a few days

Nematode larvae hatch within a few days. It's harder to ID larvae than eggs.

Free living nematodes from the environment can invade the feces

Giardia is the easiest to see when stool is fresh; the motile stage will not survive very long outside the host

Why is a direct rectal fecal sample preferred for identification of parasites?

Lowers contamination by free living nematodes and prevents eggs ID confusion between lungworms and the 1st stage larvae of GI nematodes or free-living nematodes (true internal parasite vs free living)

why should vet techs demonstrate skills for interpreting negative samples?

Parasites don't constantly produce eggs! So, just because you don't see it, doesn't mean a parasite isn't present in the animal.

Sample may be (-) for parasites, but you might see non-parasitic material which could be the culprit of the animal's clinical signs and symptoms, which helps with the diagnosis

What is the common name of Toxocara spp.?

roundworm

Why is host knowledge critical for identification of Toxoxara spp.?

Toxoxara spp are found in the small intestines of dogs and cats. Knowing the host helps determine the species of canis or cati and how to treat them.

What is the purpose of a centrifugal flotation?

It forces heavier objects to the bottom much faster than gravity alone, allowing the parasite to float to the top faster.

More effective in the parasite recovery rate of heavier eggs, like those of the Toxocara.

What eggs would you see on a centrifugal sedimentation that you couldn't see on a simple flotation?

Heavier, denser eggs. Fluke eggs typically are more dense and larger than roundworm eggs.

Using a denser media for the float can damage fluke eggs, so sedimentation is preferred for them.

How would you diagnose Toxocara spp.?

Preform a simple centrifugal float and look for eggs specific to the species you're looking at.

Keep in mind the clinical signs the animal may have.

What clinical signs would you look for to reinforce your diagnosis?

Vomiting (+/- worms), diarrhea, constipation, potbellied appearance, coughing, emaciation, poor hair coat

A client brings in a 3-week-old puppy for a wellness exam and informs you that because the puppy hasn't been exposed to the outdoors, a fecal exam isn't necessary. Why, then, would you explain to the client that a fecal sample is necessary?

The mother of the patient could've had a parasite that remained dormant until having her puppies & if so, the parasite can be passed trans placentally or trans mammary. The only way to know if the puppy is infected is to check the feces.

What happens when ancylostoma larvae undergo somatic migration?

They enter the body through the skin into skeletal muscle, fat, or connective tissue. This causes inflammation. They go into the blood, to the intestine and stay there to such blood, which then causes anemia activated by the hormones of a pregnant or lactating mother.

Why is anemia associated with hookworm infections?

Since hookworms suck blood, they secrete an anticoagulant & change their feeding sites frequently. The sites will continue to bleed from the anticoagulant, which will then cause anemia.

What preventative measure could you take when walking your dog to prevent a whipworm infection from reoccurring?

Picking up their feces and making sure they don't go near other's poop. If they're infected, make sure they aren't near others and use a preventative.

What zoonotic health threat would Ancylostoma pose if you walked your dog on a public beach?

For humans, there's percutaneous zoonosis/cutaneous larva migrans by being transferred through the skin.

Theoretically speaking, could the hookworm parasite survive in Siberia?

Usually no since they prefer warmer areas like the tropics. But if someone were to have the worm already and traveled over there, it can survive as long as its in the body.

What parasite egg is the Trichuris vulpis egg often confused with & why? How would you differentiate between the 2?

They're confused with E. aerophilus, the lungworm. They have similar shapes at a quick glance.

E. aerophilus is smaller and more broadly barrel shaped. They are also lighter in color with a rough outer shape.

How is tapeworm infection commonly diagnosed in the dog and cat?

Found in infected feces, haircoat, or bedding.

They resemble cucumber seeds that move when fresh, or white rice grains when dried.

Are the eggs of tapeworms commonly found on fecal flotations?

Usually they do fecal flotations, but could use centrifugal sedimentation. That's only for the Diphyllobothrium latum.

What is the scolex? What is its function?

The scolex is the head

It uses its acetabula to hold onto the lining of the small intestine

What is a proglottid? What is its function?

It is what the strobila is made up of.

There are different parts of it that has a function.

Immature- not sexually mature to do anything

Mature- is the body, holding the reproductive organs

Gravid- the ones that pass in feces, containing eggs

How can humans become infected with Echinococcus spp.?

Not washing hands, cleaning up feces, cooking meat thoroughly.

How can domestic animals become infected with Echinococcus spp.?

By eating infested poop, animals, and not being clean.

If a client brings you a cat that has fleas, what other parasite might you suspect it has?

Dipylidium caninum, since fleas are the intermediate host. Too much grooming is how cats get it.

Upon examining a fresh fecal sample, you notice some "rice-shaped" segments. What could you do to determine the presence of parasites?

Look for foreign body signs. Vomiting, diarrhea, weight loss. Check the haircoat for fleas. Break open a gravid proglottid.

Fecal float

How do domestic animals and man acquire trematode infections?

Infections through ingestion of I. host or through penetration of the skin by cercariae (larval form)

Describe clinical signs associated with liver flukes.

anemia

decreased milk yield

bad haircoat.

Describe clinical signs associated with lung flukes.

chronic deep intermittent cough

labored breathing

lethargy

hemoptysis

irritation in lungs

What diagnostic techniques could you use to differentiate between lung and liver flukes?

Lung flukes can be recovered by tracheal washing and X-rays.

What lab technique is best for recovering the eggs of F. hepatica? What technique WOULDN'T you use?

C. sedimentation & direct smear

C. flotation, because they're so dense

What intermediate host does all trematodes have in common?

snails

You are vacationing in S. Carolina in August. Because of the intense heat, you can't resist SWIMMING in a pond teeming with geese and snails. What parasite might you contract from this activity? What clinical signs might you display?

Avian schistosomes (blood flukes)

Swimmer's itch, rash, burning

McKinley the dog has come into your clinic and is presenting with dehydration and lethargy as a result of severe diarrhea. The owner mention that during a fishing trip in Alaska last month, McKinley ate a large number of trout. What may McKinley have contracted?

Nanophyetus salmincola, the salmon poisoning fluke

You are a contestant on the reality show Fear Factor. The network assures you that eating ants for your "gross stunt" is perfectly harmless. As a wise vet tech, you then proceed to inform the show host that you can contract what parasite?

Dicrocoelium dendritcum, the lancet fluke of sheep, goats, and cattle. This is because the ants are second intermediate hosts.

Name the species of coccidia found in the gastrointestinal tract of each:

Dogs and Cats

Horses

Ruminants

Birds

Cystoisospora sp., Toxoplasma gondii, cryptosporidiun

Eimeria

Cryptosporidiun, Eimeria

Cryptosporidium, Eimeria, Cystoisospora sp.

How is the presence of coccidia diagnosed?

Can see unsporulated in fresh feces, and use a simple float to see

What are some predisposing factors for the development of coccidiosis?

Poor sanitation, young animals, immune compromised,

What lab techniques would you use to find Giardia cysts? Trophozoites?

Cysts- fecal float using zinc sulfate, +/- iodine stain

Trophozoites- direct smear with saline, +/- iodine stain to aid in ID. Should be fresh feces

What are the primary dangers of Parascaris equorum?

Can cause GI stasis, intestinal rupture, and death

What is the diagnostic method used to diagnose Oxyuris equi?

Fecal float, but the most common is microscopic exam of cellophane tape impressions, or scraping the surface of the anus.

How do you differentiate between the coccidia oocyst from the egg of Ancylostoma?

Cysts- smaller, oval to round, thicker wall

Ancylostoma- much larger, oval, thin walls, contains 6-18 morulla

Buddy the black lab comes into your clinic with severe diarrhea (watery with large amounts of mucus) and a painful abdomen upon palpation. The owner mentions that they have recently returned from a camping trip at Beaver Pond, where Buddy spent much of his time fetching sticks from the water. What parasite might Buddy have contracted on vacation?

Giardia, because beavers are the reservoir host and it does take days

Client X calls your clinic in a panic. She has just been informed that her champion thoroughbred racehorse has Oxyuris. The big race is in 2 weeks, and her children have been spending large amounts of time getting him ready. What do you advise her about their exposure?

It's not zoonotic, so it can only spread to horse to horse.

It needs to be treated with Ivermectin, and a possible quarantine. They need to maintain stable and pasture management.