Equine Infectious Diseases Flashcards
1
Q
- Larvae L3 migrate though portal vein to the liver (peritoneum and retroperitoneum space)
A
Strongylus edentatus / equinus
2
Q
- Migration of the larvae and the corresponding immune response can result in thrombosis of the cranial or anterior mesenteric arteries leading to colic and infarction of the bowel
- Severe colic (infarction of a mesenteric artery)
- Verminous arteritis - colic with an associated painful mass at the root of the mesenteric - damage to the cranial mesenteric artery and its branches
- Antihelmintics: Benzimidazoles, pyrantel and ivermectin
- Rectal palpation: painful enlarged root of the mesentery
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Strongylus vulgaris
3
Q
- Colic in foals causing intestinal impaction
- Likely t predispose young foals to develop pneumonia
- Roundworm
- During migration in foals damage the lower respiratory tract and carry bactera
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Parascaris equorum
4
Q
- Foal heat diarrhea
- Migration through the lung causing damage
- Prevention: Treatment of post-partum mares with ivermectin.
- Transmitted to foals in the mare’s milk.
- Ivermectin or Oxibendazole are effective
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Strongyloides westeri
5
Q
- Culicoides hypersensitivity (sweet itch)
- Allergy to the saliva of the gnat. Seasonally, in the warmer months.
- Horses are pruritic and develop lesions on the poll, mane and tail form self trauma.
- Ventral midline can occur.
- More chronically, scarring can occur.
- Recurrent seasonal pruritus during summer months.
- Ventrum or dorsum, depending on the species of the fly.
- Horse develops type I hypersensitivity, developing excoriations, alopecia, and thickened skin as a result of scratching. Flies more active during dusk and dawn.
- Treatment: controlling the fly population.
- Extremely pruritic
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Culicoides
6
Q
- Larvae of the stomach worm migrate and emerge creating granulomatous lesions around the eye, male genitalia, or lower extremities.
- Inside the granuloma - dead larvae
- Granulomatous skin lesions that often contain the small calcified larvae inside.
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Habronemiasis
7
Q
- Dermatitis due to hypersensitivity to dying microfilariae
- Alopecia and scaling of the ventral midline, face and pectoral region.
- Ventral midline dermatitis is also commonly associated
- Diamond shape lesions “bull’s eye”. Annular lesions of alopecia and scaling
- Nonseasonal
- Uveitis, conjunctivitis and keratitis. Uveitis is caused by aberrant migration of the microfiliariae, when they die and inflammatory response is generated.
- Numerous annular lesions of alopecia and scaling in the face and neck.
- Signs result from hypersensitivity of dying microfilariae. Most horses will remain asymptomatic. Lesions: patchy to diffuse alopecia, erythema and scaling.
- Usually not pruritic.
- Most common parasitic cause of uveitis
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Onchocerca cervicalis
8
Q
- Equine lungworm. Horses housed with donkeys highest risk.
- Generally does not cause clinical signs in foals, however, can cause cough and respiratory signs in adults
- Definitive host: Donkey.
- Infective larva ingested and migrates through the mesenteric lymph nodes to the lungs - adults and produces eggs that are coughed up, swallowed and passes in feces
- Diagnosis: Baermann. Other techniques: Transtracheal wash (eosinophils, and possible parasite, ova or larvae).
A
Dictyocaulus arnfeldi
9
Q
- Horse bot fly (Gasterophilus spp)
- Prevention: Administer ivermectin twice annually, once early summer and again fall
- Frequently asymptomatic but treatment is recommended because bots can cause gastritis, and annoyance and stress to the horse. The larval instars can cause stomatitis and colic
- Life cycle: complete metamorphosis (3 larval instars) only one generation per year. Cycle starts wth female ovipositing eggs (early summer) on hears front legs, abdomen, flanks and shoulder. Eggs develop into 1st instar (forced to emerge by horse licking) - larvae crawl to mouth and ingested - gingiva 28 days. Larvae molt to 2nd stage move into stomach. 2nd and later 3rd stage attached to the lining of stomach (non-glandular portion) - remain immobile 9-12 months. 3rd mature - detachpass int he feces. Larvae dried in soil - pupate and remain for 1-2 months (late winter and early spring)
- Cause Gastritis
- Yellowish eggs noted on the medial aspect of cannon bone fore limb.
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Gasterophilus
10
Q
- Verminous encephalomyelitis (Halicephalobus deletrix, Draschia megastoma, Hypoderma, Strongyloid nematodes).
- Aberrant migration through CNS is uncommon; causes neurologic disease.
A
Helicephalobus deletrix
11
Q
- “Myeitis”. Sarcocystis neurona.
- No changes in CSF
- Any age. Asymmetric neurological signs, multifocal disease of the CNS.
- FDA-approved treatment: Ponazuril. Anticoccidial compound wth cidal activity. Trimethoprim-sulfamethoxazole + Pyrimethamine
- Diagnosis: Clinical signs. Western Blot, IFAT, PCR
A
Equine protozoal myeloencephalitis (EPM)
12
Q
- Sarcoptes scabei
- Treatment: Oral ivermectin and topical 2% lime sulfur spray. 2 treatments at 14 day intervals.
- Severe itching, skin thickening and crusting, usually around the head, neck and ears.
- Diagnosis: clinical signs and response to therapy (skin scraping usually unrewarding - very deep)
- Quarantined to avoid spread.
A
Sarcoptic mange
13
Q
- Equine protozoal myeloencephaitis (EPM)
- FDA-approved treatment: Ponazuril. Anticoccidial compound wth cidal activity
- Historically combination with trimethoprim sulfa
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Sarcocystis neurona
14
Q
- Horn fly. Feed on blood.
- Ventral midline dermatitis (horses housed near cattle)
- Multifocal, round, crusty lesions ventral abdomen not particularly pruritic
- Fly found around horns, back and sides of cattle on cooler days, affect the ventral abdomen on hot sunny days.
- Economicloses
- Treatment; insecticides sprays, dust bags, insecticide feed additives
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Haemtobia irritans
15
Q
- Mite: Chorioptic mange
- Affects distal limb region and can extend to ventral abdomen
- Pruritus distal limbs,particularly feathered areas
- Irritation, scabbing, and alopecia of the fetlock area, self-induced trauma due to pruritus
- Most common in winter months and causes intense pruritus
A
Chorioptes equi
16
Q
- Burkholderia mllei (previously known as Pseudomonas mallei)
- Endemic: Middle East, Asia, Africa, and South America
- Horses, donkeys, mules, and small ruminants
- Horses can become chronic and occult carriers that shed
- Potential zoonotic pathogen
- Forms: nasal gliders, pulmonary glanders, and cutaneous glanders (Farcy)
- Nasal: high fever, loss of appetite, labored breathing with cough. Viscous mucopurulent discharge or crusting around nares. Ulceration upper respiratory passages - form of star-shaped cicatrices “stellate scars”. Regional lymphadenopathy, may rupture or adhere to deeper tissues.
- Pulmonary: over several months, starting as fever, dyspnea and cough. Lung lesions commence as light colored nodules surrounded by hemorrhage or diffuse pneumonia. Nodules can become caseous or calcified, discharge to the upper respiratory tract. Nodules in other organs.
- Cutaneous: over several months, cough and dyspnea. Nodules developed in subcutaneous tissue along course of ymphatics - thickened cord-like lesions coalesce into a string “farcy pipes”. Nodular lesions of other organs.
- Identify bacteria in smears from fresh lesions as many extracellular straight G(-) rods with rounded ends.
- Diagnostic tests: PCR, ELISA and Western Blot. Important: international trade: CF (complement fixation), serology and mallein test. Mallein test most reliable, sensitive and specific; involves injection of mallein purified protein derivate intradermally into the lower eyelid. Read 24-48 hr - positive reaction (edematous swelling or purulent discharge).
- No treatment - humanely destroyed + affected carcasses burned and buried.
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Glanders
