Exam 3 Review

Ascarid eggs can remain infectious at the environment for

Several years

Parascaris spp. eggs hatch and L3 larvae begin hepatotracheal migration, arriving in the lungs approximately

1 week after infection

At what age foals immune response begins clearing Parascaris spp. infection

Approximately 5 months old

Clinical signs of Parascaris spp.-associated colic include

Elevated heart rate

Risk of impaction due to Parascaris spp. infection correlates with

Presence of worms

In acute cases of Parascaris spp.-associated colic in horses

Treatment should be directed at resolving small intestinal impaction

To minimize the risk of disease caused by Parascaris spp. in horses, current recommendations include

Faecal diagnostic testing

Bloodworms enter the horse body after ingesting

L3 from the environment

It is important to consider the large strongyles when developing an internal parasite management plan

Because no immunity develops against this particular parasite as the horse ages

Large strongyles can impair a horse’s development and performance

Yes, even small populations of large strongyles can do so

Large strongyles can result in low body weight, anaemia, and death

Yes, due to aneurysms or blood clots in major artieries

The equine bloodworm Strongylus vulgaris is regarded as the most pathogenic equine GI helminth

Correct

Strongylus edentatus and Strongylus equinus - have not been associated with distinct diseases.

True

Strongylus vulgaris ingested in third-stage larvae

Migrate sub-endothelially in intestinal arterioles toward the root of the cranial mesenteric and celiac arteries

Strongylus vulgaris adults can attach to intestinal walls and they cause clinically important anaemia in horses

They ingest blood, but they are not described as a primary cause of anaemia to horses

Infarction occurs after Strongylus vulgaris migration through intestinal arteries which results in arterial wall damage

True

How Strongylus vulgaris migration can occlude small arteries and arterioles?

The migration can result in thrombus formation and detachment of emboli from the thrombus that flow downstream

Main clinical signs associated with Strongylus vulgaris infection in horse are

Signs are nonspecific

Faecal floatation and egg counts have no value for the diagnosis of S. vulgaris infection.

True. These tests do not differentiate between various strongyle species

In the acute phase of a nonstrangulating intestinal infarction in horses due to large strongyles

There is little or no value in administering anthelminthic medications

Small strongyles (cythostomes) are rapidly becoming a threat in the equine industry through resistance to anthelmintics, or deworming medications.

True

Small strongyles take refuge in the cecum and colon of the horse

They burrow there into the lining of the large intestine, leaving the tissue scarred and inflamed

The cythostomin parasite species can infect horses, and it is common to find coinfections with 10-20 different species in a single horse

Correct

Clinically normal horses can harbour cythostomin burdens ranging from

A few thousand to more than a million worms

The cythostomin L3 larvae undergo variable amounts of arrested development (hypobiosis) for durations ranging

From a few weeks or months to several years

Horses (especially those <5 years old) can harbour hundreds of thousands of encysted larvae

True

Typically, acute larval cythostominosis affects

Typically young horses (1-4 years old, rarely foals), however, this condition can occur in mature horses as well

Clinical signs of acute larval cythostominosis include the following

Sudden onset of profuse watery diarrhoea and severe dehydration

Faecal flotation and egg counts in larva cythostominosis daignosis

They are not useful, because the condition is caused by larval stages emerging from intestinal walls

Acute larval cythostominosis is a serious condition, with a mortality rate of approximately 50%

True

A single oral dose of moxidectin (0.4 mg/kg) has been documented to decrease the number of later larval stages (L3 and mucosal L4) of cythostomins by approximately 60-80%

True

Which host acts as intermediate hosts for Anoplocephala perfoliata?

Free-living oribatid mites (accidentally ingested by horses while grazing)

Tapeworm-associated colic can occur when large numbers of A. perfoliata attach to cecal and ileal walls

Correct

Definitively identifying tapeworms as the cause of colic has important implications for managing acute cases

It has limited implication for acute cases, but it is valuable for subsequently advising clients about future herd management

Currently available equine tapeworm diagnostic standard egg-counting techniques (eg, the McMaster technique) are useful and of high sensitivity

They have been shown to have a diagnostic sensitivity of <10%, making them practically useless for this purpose

The recommended treatment are Anoplocephala infections is

Praziquantel

Horse bots are the parasitic larvae of botflies Gasterophilus spp.

Correct

Gasterophilus larvae can spend up to 8-10 months within the horse. Outside of the horse’s body, they pupate in the soil for maximum 1 week before adult botflies emerge.

They pupate in the soil for 3-5 weeks before adult botflies emerge

The gastric stages of Gasterophilus can be numerous but rarely produce clinical signs; however, erosions and ulcerations do occur.

True

Diagnosis of Gasterophilus is made by

Gastroscopy to visualize second and third instars attached to gastric mucosa

Treatment of Gasterophilus larvae in the horse is made using

Ivermectin (0.2 mg/kg, PO, once) has high efficacy against oral and gastric stages

Habronema and Draschia spp. are vector-borne parasites of horses

They use muscid flies as intermediate hosts

Habronema adults are found in loose contact with gastric mucosa

True, but they do not produce clinical signs

Habronema eggs can be easily detected in faecal flotation

False

Gastric stages of Habronema spp. are expected to be susceptible to

Macrocyclic lactones

Gravid Oxyuris spp. females migrate through the descending colon and rectum to deposit their eggs in packets onto perianal skin (8,000-60,000 eggs in one deposit) and then die in the environment.

Correct

Adult Oxyuris spp. females can sometimes be observed in the horse’s faeces

Possible and look similar to ascarids due to their stout appearance (length 5-10 cm). However, their tapered posterior ends can confirm identification

Oxyuris equi larval stages can cause inflammatory reactions in the mucosal walls of the cecum and ventral colon

True, though associated clinical signs have not been described

Egg masses of Oxyuris equi can produce local perianal irritation and pruritus that can progress to tail rubbing

True. Also, yellow or brown egg masses can sometimes be observed in the perianal area

Diagnosis of Oxyuris equi infection is made by

Direct microscopy of egg mass material from the perianal area (morphologically distinguishable from other equine helminth egg types)

Effective treatment against Oxyuris equi Includes the administration of

Fenbendazole

Oxyuris equi is a zoonotic parasite

Not true

Strongyloides westeri is an intestinal threadworm that has been associated with small intestinal enterisis, resulting in diarrhoea commonly in young foals.

True

What is the most important route of Strongyloides westeri infection in young foals?

Lactogenic transmission

The highest concentration of Strongyloides westeri larvae in milk occurs

10-14 days post partum

Strongyloides westeri larvae obtained lactogenically do not migrate through extraintestinal tissues in foals

Correct

Strongyloides westeri larvae obtained via oral ingestion or percutaneous invasion are believed to migrate through the lungs in foals

Correct

The percutaneous route of Strongyloides westeri infection can lead to dermatitis

Correct, on distal extremities

Diagnosis of disease associated with Strongyloides westeri infection in horses is based on

Both the number of Strongyloides egg counts and on the presence of third-stage larvae, as identified in coproculture

Strongyloides westeri infection is treated very difficult due to the extensive spread of anthelmintic resistance

False

Trichostrongylus axei infections in humans from horses have been described

Infection occurs via the ingestion of infective larvae present on contaminated lettuce, cabbage, or other produce

Psoroptes ovis infests horses, causing psoroptic mange. A very common disease in horses.

A very rare disease of horses

Psoroptes ovis infestations can produce lesions on thickly haired regions of the body, such as under the forelock and mane

Correct

The most common form of mange in horses is

Chorioptes bovis

Ticks on horses should be eliminates as

Should be removed as quickly as possible, not to wait for it to detach

Babesia equi (reclassified as Theileria equi) infection is often asymptomatic but can result in outbreaks of disease characterized by fever, anaemia, and lethargy, leading to death of some animals.

Correct

Effective control of lice in horses should address

Both

Tabanus spp. (horse flies) only the females feed on vertebrate blood

Correct

Many of the insecticide adulticide compounds used for other biting flies can kill horse flies (Tabanus spp.), making control easy task.

Fasle. Horse flies are intermittent feeders for only a short time, they may not be exposed to these compounds long enough to be affected

Culicoides spp. feed on horses, which often become allergic to their bites.

Bites lead to scratching and rubbing these areas, causing alopecia, excoriations, and thickening of the skin.

The life cycle of Stomoxys calcitrans is completed on the host

Wrong. The larval and pupal forms develop in decaying organic matter

Stable flies control

The main consideration in stable fly control is sanitation, which can effect up to 90% control

Reproduction of Hippobosca equina flies

The fly lays larvae which rapidly pupate over one hour and exhibit varying duration as pupae

Hepatic coccidiosis in rabbits at necropsy present

Small, yellowish white nodules are found throughout the hepatic parenchyma

It is important not to confuse the rabbit coccidian oocysts with the normal yeast (Cyniclomyces guttulatus)

True, as it is commonly seen in faecal examinations

Rabbits cannot develop immunity to hepatic coccidiosis

Wrong. Rabbits treated successfully are immune to subsequent infections

Treatment of rabbit coccidiosis will not be successful unless a sanitation program is instituted simultaneously

Correct, both are needed

What is the best choice to disinfect cages or ancillary equipment exposed to faecal material for coccidiosis

Ammonia (10%) solution is lethal to oocysts

Good sanitation programs can eliminate both hepatic and intestinal coccidiosis in rabbits

Good sanitation programs that can eliminate hepatic coccidiosis do not seem to eliminate intestinal coccidiosis

Rabbits are intermediate hosts for the canine tapeworm Taenia pisiformis.

Right

Cysticercus pisiformis generally do not make clinical signs, and diagnosis occurs at necropsy.

Correct

Psoroptes cuniculi clinical signs include

Infested rabbits scratch and shake their head and ears

Mites on rabbits may be treated with selamectin

Correct

Cheyletiella mites are diagnosed by

Both of these

Cheyletiella mites are zoonotic

They may cause a mild dermatitis, especially on the arms

Rabbits are rarely infested with either Sarcoptes scabiei or Notoedres cati. What are the clinical signs?

The infested rabbits are extremely pruritic

Fipronil is effective against mites on rabbits

Its use is contraindicted in rabbits because of potential toxicity

Do flea collars protect rabbits from fleas?

Their use in rabbits is not recommended

Passalurus ambiguus, the rabbit pinworm

Usually is not clinically significant

Single treatments against Passalurus ambiguus are very effective, because the life cycle is direct

Single treatments are not effective, because reinfection is common

What is the mode of infection for Encephalitozoon cuniculi?

Rabbits can get infected in utero or by ingestion the spores, which are shed via the urine of affected animals

What are the main organs involved in the manifestation of the clinical signs of Encephalitozoon cuniculi following in utero infection?

Kidney, CNS, and lens