99:
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is available for PHF, it does not cover all strains of the bacterium, and recent vaccine failures seem to be on the rise. Additionally, the vaccine usually produces a very weak immune response, which may only lessen the severity of the disease rather than prevent it. The vaccine is administered twice
133:. It is thought that the main mode of infection is by accidental ingestion of infected adult insects, who may fly into barns and die in stalls or on pastures after enclosure. Experimental infection has been produced with oral administration of infected insects and subcutaneous inoculation of
194:(20 to 40 percent of cases). Infected horses founder usually within three days of the initial symptoms, thought to be secondary to endotoxemia. Death may occur and is usually due to severe laminitis leading to founder.
146:; these insects hatch en masse and may be found littering the ground in nearby stables, where they are attracted by light. The entire natural history and life cycle of
329:
Cleaning water buckets and feed areas frequently and keeping food covered will reduce the chance that the horse will accidentally ingest infected insects
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a year, in early spring and in early summer, with the first one inoculation given before the mayflies emerge and the second administered as a booster.
255:
Supportive care for severe cases is aimed at minimizing the effects of endotoxemia and preventing laminitis. This may include
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241:
150:
has yet to be elucidated, but bats and birds may be wild reservoirs of infection. Unlike other causes of acute
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opt to initiate treatment right away, as the disease can progress quite quickly. Veterinarians may also run
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Several outbreaks of PHF have been found to coincide with mass emergences of burrowing mayflies of the genus
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Some veterinarians have started making recommendations for farm management to try to prevent this disease:
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102:
Accidental ingestion of the mayfly is thought to be one of the main modes of transmission of PHF.
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barriers along bodies of water may encourage aquatic insects to stay near their places of origin
51:, in the 1980s, but cases have been described in many other parts of the United States, such as
26:) is a potentially-fatal febrile illness affecting horses caused by the intracellular bacterium
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280:
48:
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Signs and symptoms of PHF include acute-onset fever, depression (sometimes profound),
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Turning off outside lights around the barn will prevent insects from being attracted
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60:
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182:-like symptoms, decreased manure production, profuse watery non-fetid diarrhea
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or plasma for endotoxemia; supportive shoeing; low doses of intramuscular
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testing to look for the bacterium in the blood and feces. However, most
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64:
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122:
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Horses may not always display any other symptoms beyond a fever.
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due to protein imbalances, abortion by pregnant mares, and acute
137:. All attempts to transmit the disease using ticks have failed.
63:. Currently, it is found in more than 40 U.S. states and
248:, while severe cases are usually treated with intravenous
229:
may be taken to track the progress of laminitic horses.
114:(fluke). The life cycle of the fluke takes it through
166:, PHF is not spread directly from horse to horse.
43:. It was first described in areas surrounding the
121:and back into water, where it is ingested by the
205:Diagnosis of PHF is accomplished by measuring
259:and electrolytes to counteract the diarrhea;
125:stages of several aquatic insects, including
8:
225:panels to determine the course of care.
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244:. Mild cases may be treated with oral
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271:; administration of products such as
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367:Pascoa, Elaine. "PHF Prevention."
14:
75:The causative agent of PHF is
1:
386:The Merck Veterinary Manual
16:Bacterial disease of horses
429:
242:tetracycline antibiotics
32:. PHF is also known as
108:Neorickettsia risticii
103:
77:Neorickettsia risticii
29:Neorickettsia risticii
382:"Potomac Horse Fever"
219:complete blood counts
101:
110:is believed to be a
83:), an intracellular
154:in horses, such as
20:Potomac Horse Fever
369:Practical Horseman
277:activated charcoal
269:dimethyl sulfoxide
265:flunixin meglumine
263:such as Banamine (
257:intravenous fluids
221:and chemistry and
170:Signs and symptoms
104:
81:Ehrlichia risticii
371:July 2008: 60-66.
240:responds well to
38:Equine Monocytic
34:Shasta River Crud
420:
397:
396:
394:
393:
378:
372:
365:
289:polymyxin B
281:nasogastric tube
238:N. risticii
148:N. risticii
135:N. risticii
49:Washington, D.C.
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267:); intravenous
250:oxytetracycline
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207:antibody titers
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96:
73:
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12:
11:
5:
426:
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413:Horse diseases
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404:
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297:pentoxifylline
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106:The vector of
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2:
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215:veterinarians
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50:
47:northwest of
46:
45:Potomac River
42:
41:
35:
31:
30:
25:
21:
390:. Retrieved
385:
376:
368:
319:Maintaining
314:
306:
293:acepromazine
254:
237:
236:
204:
196:
173:
161:
155:
147:
141:
139:
134:
127:caddis flies
107:
105:
94:Transmission
80:
76:
74:
61:Pennsylvania
40:Ehrlichiosis
37:
33:
27:
23:
19:
18:
246:doxycycline
227:Radiographs
223:electrolyte
184:endotoxemia
176:inappetence
163:Clostridium
85:rickettsial
392:2007-06-14
334:References
303:Prevention
285:endotoxins
157:Salmonella
116:freshwater
79:(formerly
57:California
273:Biosponge
233:Treatment
201:Diagnosis
192:laminitis
143:Hexagenia
112:trematode
88:bacterium
53:Minnesota
407:Category
321:riparian
307:While a
283:to bind
131:mayflies
309:vaccine
178:, mild
152:colitis
388:. 2006
295:; and
261:NSAIDs
123:larval
119:snails
65:Canada
59:, and
188:edema
180:colic
71:Cause
279:via
160:and
129:and
36:and
275:or
211:PCR
209:or
24:PHF
409::
384:.
342:^
299:.
287:;
252:.
186:,
90:.
67:.
55:,
395:.
22:(
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