What is the pathological process that involves inflammation and necrosis of vascular walls?
- Usually 2' to:
- Immune response
Hallmark of vasculitis?
Predominant involvement of small vessels in the skin
C/S associated with vasculitis? 9
- Edema- Peripheral/Limb
- Ulceration of MM
- Vascular necrosis in any organ (lameness, colic, dyspnea)
Sequela to vasculitis? 4
- Thrombophlebitis (occluded jugular v)
4 common causes of vasculitis?
- Equine viral arteritis
- Equine purpura hemorrhagica
- Equine infectious anemia
What is a non-contagious disease that is sequela to systemic diseases like Strangles?
Purpura hemorrhagica (EPH)
Signalment often associated with EPH?
- Young to middle aged horses
- 2-4 weeks following respiratory infection
- (not neonates, up to ~8yrs old)
Expected findings on MDB with purpura hemorrhagica? 5
- Elevated muscle enzymes (CK, AST)
- (thrombocytopenia rare)
Classic findings on skin biopsy with purpura hemorrhagica? 3
- Leukoclastic vasculitis w/necrotic vessels
- Complexes of IgM/IgA (type 3 hypersensitivity)
- Strep M protein
EPH Tx? 4
- Tx primary condition
- Hydrotherapy + Distal limb bandages
- *steroids* 2-4wk minimum
Which Vx is associated with EPH formation?
How can this be avoided?
Strep. equi (strangles)
Titers >1:1600 = poor candidate for the Vx, Greater risk for causing EPH
which infectious disease causes vasculitis and abortions?
equine viral arteritis
Mechanism of transmission for EVA?
- Respiratory secretions
- Fetal fluids
- NOT arthropod borne
C/S's in a horse with EVA? 6
How long after infection will signs appear?
- "Pink eye"
1-10days post infection
How far into gestation will mares abort if infected with EVA?
Will mare remain carrier for life?
Abort 3-10 months
- Mares NOT carrier for life
- *stallion remains carrier for life*
Mare may show no signs while shedding and then fully recovers w/long natural immunity
Target organ with EVA?
- Blood vessels
- (=Fibrinoid necrosis of tunica media w/perivascular lymphocytic infiltrates; thrombi)
why is castration of stallion curative for EVA?
- Testosterone dependent disease
- Virus resides in ejaculate
- (also can not become infected until after puberty - testosterone)
What happens to foal born to mother infected with EVA (assuming she doesn't abort)?
Interstitial pneumonia in the newborn
Dx of EVA?
4 fold increase in titer
Serum + Stallions then get PCR/culture/viral isolation
- Can't distinguish Vx from infection
- Can prevent infection in males vaccinated before puberty
how is equine infectious anemia transmitted? 4
- Tabanid insects (horseflies, deer flies)
- Blood transmission
- Fomites (re-use of needles, etc)
- Verticle (in utero/colostrum)
In the acute stage of EIA there is a burst of viremia that leads to what C/S's? 4
- *thrombocytopenia*(evident before anemia?)
Findings with chronic EIA?
- Sick horses "swampers" = acute or chronic Episodes
Would horse in the inapparent stage of EIA test + for the virus?
- No viremia during inapparent stage
What is a risk and possible cause of death in any horse exhibiting signs of EIA?
- (virus attacks endothelium - vasculitis - death)
Gold standard Dx test for EIA?
Coggin's Test (USDA approved test) = agar gel immunodiffusion for p26 Ag
Since the coggin's test requires 24 hours to complete, what is another option for testing EIA?
- ELISA = serology for detection of transmembrane glycoprotein p26 and gp45
- (all positives must be confirmed w/coggins)
EIA is a reportable disease. What happens to EIA positive horses?
- Remove from population (euthanasia)
- Brand/tattoo and separate at least 200yd from other horses
How is Equine piroplasmosis transmitted?
Ixodes ticks carry protozoa - theileria equi and babesia caballi
What does equine piroplasmosis cause?
How common is this disease in the US?
Will infected horses be carriers for life?
Acute hemolytic anemia (intravascular)
Seropositive for life
How old are horses when infected with piroplasmosis?
- <1 yr (naive horse intro to endemic herd)
- Neonates (In utero, poor prognosis)
C/S for Piroplamasmosis...
- No signs and low parasitemia
- Incr. RR/HR
Dx for Piroplasmosis?
- Blood smear + C/S (☩ = merozoites)
- *Competitive ELISA* (TOC)PCR (early & carrier)