Equine - Gastrointestinal Dz Flashcards
1
Q
Describe the aetiologic agent of Potomac Horse Fever (PHF).
A
- Neorickestia risticii.
- Obligate intracellular gram negative bacteria.
2
Q
Describe the proposed pathophysiology of PHF.
A
- Intracellular parasite; infects peripheral monocytes and macrophages, SI epithelial cells and large colon mast cells.
- Incompletely understood; horses appear to develop CSx and complications similar to Salmonellosis.
- Experimental infection –> fever in 2-4d and GI signs in 10-14d.
- CSx of sepsis incl fever, leukopaenia, MM congestion, hypercoagulability.
- Magnitude of intestinal inflammation less than Salmonella, but hypoproteinaemia can be severe through GI loss.
3
Q
Described the epidemiology of PHF.
A
- Association between affected horse and proximity within 5 miles of a river is strong.
- Trematode stages have been found in aquatic snails (Pleurocerdia, Juga spp, Acanthatrium spp, Lecithodendrium spp) and aquatic insects (cadis flies).
- Suggested route of transmission is ingestion of aquatic insects or trematode stages release by snails into water.
4
Q
List clinical signs of PHF.
A
- Anorexia, lethargy, fever, depression, inappetence.
- GI signs from mild colic and soft faeces to severe dxa.
- Congested MMs.
- Laminitis in up to 30% horses w PHF (w or w/out dxa).
5
Q
Outline diagnosis of PHF.
A
- Serum IFA or ELISA: 4 fold inc b/w acute and convalescent samples confirms infection, but negative does not rule it out b/c CSx can be delayed up to 14d post-infection.
- qPCR of N. risticcii in leukocytes (whole blood) appears to be sensitive and specific in horses w supportive CSx.
6
Q
Describe treatment and prevention of PHF.
A
- Oxytet IV for 4d, can use doxy but absorption may be poor with GI dz; some horses replase 2-3 wks after initial resolution but ABs should eliminate infection.
- IVFT.
- +/- plasma.
- Endemic areas vacc horses early Spring and early to mid-Summer –> dec severity of dz.
