Etiology Corynebacterium psuedotuberculosis
Soil-borne, gram-positive, bacillus, intracellular, facultative anaerobe
Cultures in ~48 hours
2 biotypes Biovar equi
Multiple strains Biovar ovis
Multiple strains
Epidemiology 3 general forms
External abscesses 96% Internal abscesses 2% Ulcerative lymphangitis 2%
Cellulitis with multiple draining lesions
Entry via abrasions and/or wounds to the skin or mucous membranes Summer sores (ventral midline dermatitis)
Horses, cattle, humans, sheep, goats
Epidemiology Transmission
Horse to horse contact Insects “Other” vectors Contaminated soil
“Contagious” Not as bad as Strangles Absolute quarantine not required
Survival times Up to 2 months in hay or shavings More than 8 months in the soil
Epidemiology Yearly fluctuations
Herd immunity Environmental factors
Rainfall Temperature
Hot, dry
Not definitively determined at this time
All breeds, all ages are at risk
Risk factors Appropriate environmental conditions
map review
<5 years or age
Horses in contact with others on summer pastures
Horses housed outside or with access to an outside paddock > stabled horses
Pathogenesis Incubation period
7 to 28 days
Intracellular survival
Toxins reduce disease fighting abilities Similar to that produced by the Brown Recluse spider
Recovery 2 to 4 weeks
Although rare, horses can develop persistent recurrent infections lasting for more than 1 year
External Abscesses Clinical signs
Edema - 100% of the time Lameness or stiffness
100% of the time location, location
Anorexia - general malaise Fever ~25% of the time Weight loss Non-healing wounds
Internal Abscesses Clinical signs
Consistent with the involved organ or area Changes in lab work
Blood Abdominal fluid Thoracic fluid Urine Serology
Most commonly found in the liver or lungs
Treatment Time
“You want me to..............wait?!” Yeah…
lets allow the abscess to “cook” for a bit
Drainage Ultrasound guidance
Determine vascularity, depth, site
Treatment Antibiotics
Variable Penicillins, Sulfas Rifampin, Doxycycline
Antiinflammatories Bute, Banamine, Equioxx, Dexamethasone
Hydrotherapy Cold or warm
Survival Rates <1% mortality rate associated with
external abscessation with treatment
30 to 40% mortality rate associated with internal abscessation with treatment 100% without
Ulcerative lymphangitis Similar mortality to internal abscesses
Long-term recovery In some horses, it can take up to 1 year for
them to fully recover from the effects of pigeon fever
Some horses will never fully recover from the effects of pigeon fever They die They are chronically lame They can suffer irreversible damage to vital
organs
Up Coming Classes
September
30th Veterinary Medicine 101: I want to be a veterinarian
October
7th Forelimb Lameness
21st Hindlimb Lameness
November
4th Colic and GI Disease
18th Respiratory Disease
December
2nd Disease Recognition