navle questions Flashcards
In order of occurrence, the typical pattern of events in the life cycle of a coccidian parasite, such as Eimeria organisms, are:
a. schizont, schizont, gametocyte, oocyst, sporocyst, sporozoite
b. oocyst, gametocyte, schizont, schizont, sporozoite, sporocyst
c. oocyst, sporocyst, sporozoite, gametocyte. schizont, schizont
d. gametocyte, schizont, schizont, oocyst, sporocyst, sporozoite
e. schizont, schizont, oocyst, gametocyte, sporocyst, sporozoite
A.
Necropsy of a horse reveals infection of the skeletal and cardiac muscle with Sarcocystis bertrami. Typical clinical signs of chronic myositic infection (infection with the bradyzoite stage) with this parasite, as with other species of Sarcocystis, are:
a. muscle pain and loss of function
b. inappetence and wasting
c. diarrhea and dehydration
d. central nervous system signs
e. absent
E.
Concerning infestations of ectoparasites in horses, which statement is least accurate?
a. Lice infestations most commonly involve the biting louse (Damalinia equi) and the sucking louse (Haematopinus asini). Infestations can occur at any time but tend to most common in the winter.
b. Scabies in horses usually begins on the head, Chorioptes infestations begin on the legs, and Psoroptes infestations begin on the trunk.
c. Culicoides hypersensitivity is one of the most common fly-bite dermatoses of horses. In general, the head, tail, and ventrum are affected; pruritus may be generalized in severe cases.
d. Onchocerciasis can cause cutaneous and ocular lesions. Cutaneous lesions are represented by alopecia, ulcerations, depigmentation, and scaling. The face, neck, and ventral midline are most commonly infested. The filarial nematode is transmitted by Musca domestica.
e. The treatment of choice for equine mite and lice infestation is ivermectin.
D.
Concerning tapeworm infection, which statement is least accurate?
a. The common tapeworms of horses are Anoplocephala magna and Anoplocephala perfoliata.
b. The life cycle involves snails as intermediate hosts.
c. Tapeworms are more common in adult horses than in foals.
d. Clinical signs attributable to tapeworm infection include unthriftiness, intestinal ulceration, and intussusception.
e. Pyrantel pamoate is the treatment of choice against Anopolocephala.
B.
A smear of blood collected from a newborn foal contains microfilariae identified as those of Setaria equina. If the microfilariae in the foal are not killed by anthelmintic treatment, they will:
a. develop to adults within the abdominal cavity
b. develop to infective larvae in the dermis
c. cause “summer sores” in the saddle area
d. die from natural causes without serious consequences to the foal
e. migrate to the brain, causing serious neurological disease
D.
Which procedure is required to control house flies and stable flies?
a. frequent spraying of insecticides around the barn
b. applying repellants and insecticidal sprays to horses
c. installing electric light traps around barns
d. proper disposal of hay and manure
e. administering oral insecticides
D.
Concerning larval cyanthostomiasis, which statement is least accurate?
a. Larval cyanthostomiasis is most common in young horses but can occur in horses of all ages.
b. Clinical signs of cyanthostomiasis may include diarrhea, colic, weight loss, dependent edema, and delayed shedding of the winter haircoat.
c. The disease is seasonal and associated with emergence of larvae from the gut wall after hypobiosis.
d. Adult cyanthostomiasis does not usually cause diarrhea but can contribute to protein-losing enteropathy.
e. Ivermectin and some benzimidazole dewormers are the only anthelmintics effective against third-stage larvae encysted in the gut wall.
E.
Concerning onchocerciasis, which statement is least accurate?
a. Cutaneous onchocerciasis is characterized by alopecia and depigmentation.
b. Adult Onchocerca cervicalis worms live in the nuchal ligament.
c. Culicoides gnats ingest the microfilariae of Onchocerca in the dermis
d. Ivermectin therapy kills both microfilariae and adult O. cervicalis worms.
e. Lesions can appear on the face, chest, withers, and ventral midline.
D.
Infection of a horse with large numbers of Oxyuris equi is likely to lead to:
a. verminous arteritis
b. gastritis
c. accute diarrhea in late winter and spring
d. bare patches around tail and perineum
e. chronic bloody diarrhea
D.
Donkeys infected with Dictyocaulus arnfieldi are considered a threat to horses because they contaminate the environment with larvae. Grazing horses acquire lungworm infections by ingesting:
a. free-living infective larvae
b. infective larvae in a snail intermediate host
c. infective larvae in a oribatid mite
A.
Concerning fecal examination for parasite ova in horses, which statement is most accurate?
a. Fecal egg counts (eggs per gram of feces) correlate well with the severity of clinical signs.
b. Parasitism can be ruled out as a cause of chronic diarrhea in horses when fecal egg counts are less than 500 eggs/ g feces.
c. Parasitism can be ruled out as a cause of chronic diarrhea in horses when the fecal examination is negative for parasite ova.
d. Examination of feces from several horses in same environment for parasite ova is useful for determining the efficacy of the parasite control program.
e. Parasitism can be ruled out as a cause of diarrhea in horses when fecal egg counts are less than 200 eggs/ g feces.
D.
Concerning the parasitic life cycle of Parascaris equorum, which statement is least accurate?
a. The life cycle begins with ingestion of infective eggs.
b. Third-stage larvae migrate via the mesenteric artery to the liver in the first week after infection.
c. Larvae migrate to the lungs about 10 days after infection
d. Larvae migrate within the lungs for about 1 week before proceeding to the major airways.
e. Most larvae arrive in the small intestine 2 to 3 weeks after ingestion.
B.
In horses the larvae of Strongylus vulgaris are the pathogenic stage of this parasite. Damage is caused by migration of larvae within the:
a. bile canaliculi of the liver
b. islet cells of the pancreas
c. intima of the cranial mesenteric arteries
d. lymphatic vessels in the small intestine wall
e. meninges of the spinal cord
C.
Concerning the evaluation of efficacy of parasite control programs, which statement is least accurate?
a. At 1 to 2 weeks after anthelmintic therapy, 20% of the horses should be evaluated for nematode ova.
b. Tapeworm ova are best detected using the Wisconsin technique.
c. Fecal egg counts should be performed on all fecal samples that show eggs on fecal flotation.
d. Fecal egg counts cannot predict the number of parasites a horse harbors.
e. Pasture contamination can be considered low if fecal egg counts are below 50 eggs/ g.
B.
Anthelmintic treatment for Parascaris is equorum infection:
a. is most important with respect to the patient’s parasite burden
b. should consist of a benzimidazole if a rapid kill is desired
c. should consist of a avermectin if a rapid kill is desired
A.
Which of the following is associated with Parascaris equorum infection?
a. weight loss
b. coughing and nasal discharge
c. lethargy
d. slow weight gain
e. protein-losing enteropathy
E.
Cutaneous habronemiasis (summer sores) is a:
a. disease of the lymphatics of the extremities
b. skin disease of the ventral midline, transmitted by midges
c. seasonal granulomatous skin disease transmitted by house flies and stable flies
d. seasonal granulomatous skin disease transmitted by Culicoides gnats
e. skin disease of the face, transmitted by Colicoides gnats
C.
The prepatent period for Parascaris equorum infection is:
a. 75 to 100 days
b. 65 to 120 days
c. 55 to 65 days
d. 35 to 50 days
e. 115 to 135 days
A.
A large cyst (8 cm in diameter) is found in the lung of a cow in Utah. The cyst contains thousands of microscopic tapeworm scolices. This cyst represents which of the following?
a. A sparganumk
b. A cysticercus
c. A coenurus
d. A hydatid
e. A cysticercoid
D. These findings describe a hydatid cyst.
Cattle become infected with Ostertagia ostertagi by which of the following means?
a. ingestion of infective larvae
b. ingestion of infective oribatid mites
c. transmammary migration of infective larvae
d. transplacental migration of infective larvae
e. ingestion of infective larvae encysted in water plants
A. Ostertagia ostertagi, like most other trychostrongyles and strongyles, has a direct life cycle.
The most likely cause of diarrhea without intestinal blood loss in a 2-week-old calf is which of the following?
a. Sarcocystis cruzi
b. Bunostomum phlebotomum
c. Eimeria bovis
d. Toxoplasma gondii
e. Cryptosporidium parvum
E. In certain housing situations, it is not uncommon for 100% of the calves to be infected by the third week of life. Cryptosporidium muris, another mammalian parasite, also found in cattle, but usually in older animals. The oocysts of C. parvum are 5mm, and those of C. muris are 7mm.
Occasionally, cattle serve as host to a long adult tapeworm, Moniezia benedeni. Cattle become infected by ingesting which of the following?
a. infective eggs
b. infective ants
c. larvae on aquatic plants
d. infected snails
e. infected free-living mites
E. One tapeworm of people and rats, Vampirolepis nana, has no need of an intermediate host.
Horses in herd develop ventral midline dermatis, that disappears each winter. The shelter where they are fed each evening is near a stand of rather open forest. After other measures fail, a veterinarian suggests placing a slowly revolving fan at one end of the shelter. The fan is an overwhelming success during the next spring and summer. The decision to suggest the fan was based on the guess as to the causative agent from the veterinarian’s knowledge of the flight behavior of which of the following?
a. mosquitos
b. tabanids
c. black flies
d. biting midges (heleids, ceratopogonids)
e. deer flies
D. Midges are very weak fliers that can be deterred with fans.
Skin scrapings of a lesion at the base of the tail of a cow reveals mites. The mites are identified as Chorioptes bovis by which of the following?
a. Long, jointed pedicles of the pretarsi
b. Long, nonjointed pedicles of the pretarsi
c. Short pedicles of the pretarsi
d. Elongate body
e. Lack of caruncles on the pretarsi
C. The pretarsi of Chorioptes bovis have short pedicles
Within a steer’s ear, on examination, there appear to by very large mites (about 1 cm in diameter). The parasites are subsequently identified as a stage of the soft tick Otobius megnini. The stages present in the ear of this steer are which of the following?
a. larvae, nymphs, and adults
b. nymphs and adults
c. nymphs and eggs
d. eggs, larvae, and nymphs
e. larvae and nymphs
E. Larvae and nymphs of Otobius megnini can be observed in the ear canal of infested cattle.
Winter coccidiosis in cattle is characterized by which of the following?
a. anemia and icterus
b. wasting and myositis
c. diarrhea and dysentery
d. cardiac failure
e. fever and loss of hair at the base of tail
C. Coccidiosis causes diarrhea in the winter.
In horses, small strongyles (cyanthostomes) can cause disease when present in large numbers or, apparently, when there is mass emergence of arrested larvae. In which of the following are the hypobiotic larvae (arrested larvae) of these worms located in a parasitized horse?
a. the lungs
b. the cranial mesenteric arteries
c. caseous nodules on the small bowel
d. the wall of the cecum and colon
e. the wall of the stomach
D. Arrested larvae are found in the cecal and colonic wall.
Which of the following diseases is not transmitted by hard ticks (Ixodidae)?
a. Babesiosis
b. Ehrlichiosis
c. Theileriosis
d. Lyme disease
e. Rift Valley fever
E. Rift Valley fever is caused by a virus that is transmitted by mosquitoes
The most likely cause of diarrhea without intestinal blood loss in a 2-week-old calf is which of the following?
a. Sarcocystis cruzi
b. Bunostomum phlebotomum
c. Eimeria bovis
d. Toxoplasma gondii
e. Cryptosporidium parvum
E.
In certain housing situations, it is not uncommon for 100% of calves to be infected by the third week of life. Cryptosporidium muris, another mammalian parasite, also found in cattle, but usually in older animals. The oocysts of C. parvum are 5mm, and those of C. muris are 7mm.
In a calf that died from severe diarrhea associated with high serum pepsinogen levels, necropsy reveals the rumen, reticulum, and omasum to be full of feed, while the remainder of the alimentary tract is virtually empty. The mucosa of the abomasum is covered with gray-white, 3- to 5-mm nodules, each of which contains a small worm. The parasite responsible for this type of lesion in cattle is which of the following?
a. Hemonchus placei
b. Trichostrongylus axei
c. Ostertagia ostertagi
d. Nematodirus helvetianus
e. Bunostomum phlebotomum
C. Ostertagia species typically cause abomasal nodules.
Which of the following is the major clinical sign of hemonchosis in sheep?
a. pale mucus membranes
b. diarrhea
c. hypoproteinemia
d. constipation
e. bloody diarrhea
A. This is a manifestation of anemia.
Young beef cattle in Mississippi develop anemia and anascara during a wet period of the summer. None of the animals show any signs of diarrhea and some seem constipated. One animal dies and necropsy reveals numerous red and white worms, 20 to 30 mm long, within the abomasum. The worms most likely responsible for the disease in these cattle is which of the following?
a. Hemonchus placei
b. Trichostrongylus axei
c. Ostertagis ostertagi
d. Nematodirus helvetianus
e. Bunostomum phlebotomum
A.
The white reproductive organs of the female can be seen through the red translucent body spiraling about the intestine, giving the worm a “barber pole” appearance.
A 4-year-old Standardbred mare developes paralysis of the right side of its face. Despite various treatments, the disease progresses to lameness and
D.
In horses, the larvae of Strongylus vulgaris are the pathogenic stage of this parasite. Damage is caused by migration of larvae within which of the following?
a. The bile canaliculi of the liver
b. The islet cells of the pancrease
c. The intima of the cranial mesenteric arteries
d. Lymphatic vessels of the small intestine wall
e. The meninges of the spinal cord
C.
Strongylosis is a common cause of colic in horses.
