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Rocky Mountain Spotted Fever |
RMSF presents seasonally (March-October). The most common clinical
signs in dogs are:
- high fever (temperatures of 106F and above are not uncommon)
- anorexia
- muscle and joint pain
- facial edema or stocking edema of the extremities
- Scrotal edema in male dogs is very characteristic. Occasionally
this will progress to complete scrotal necrosis.
- Thrombocytopenia, petechiae, retinal hemorrhage, CNS signs
and possibly shock may be evident.
- The rash that is so characteristic of Rocky Mountain "spotted"
fever in humans doesn't appear to occur in dogs.
- The pathogenesis of RMSF involves replication of the organism
in endothelial cells, leading to vasculitis, increased vascular
permeability and petechiae.
In enzootic areas of the East Coast of the U.S., Lyme disease
(LD) may appear clinically similar and can be a difficult differential
diagnosis. However, in comparison to dogs with LD:
- Dogs with RMSF are generally remarkably more depressed, myalgic
and arthralgic.
- Dogs with Lyme disease typically don't develop the edema
and petechiae that occur with RMSF.
