Vascular permeability and coagulation during Rickettsia rickettsii infection in dogs.
The vascular permeability of the ocular fundus, alterations in the coagulation system, and plasma concentrations of thromboxane B2 (TXB2) and 6-keto-prostaglandin F1 alpha (6-keto-PGF1 alpha) were studied in dogs following intradermal inoculation with 5 x 10(5) TCID50 of Rickettsia rickettsii. Twenty-four to 48 hours after the onset of fever and rickettsemia, multifocal areas of retinal vasculitis were evident, which corresponded to areas of altered vascular permeability demonstrated by fluorescein angiography. The number and intensity of retinal vessels with sodium fluorescein leakage peaked during the second week after inoculation, and retinal vascular permeability remained altered during the third week of infection, well past the phase of clinical and clinicopathologic recovery. Development of retinal vasculitic foci was associated with thrombocytopenia, increased concentrations of circulating fibrinogen, and slight prolongation of activated partial thromboplastin time. Increased concentrations of fibrin/fibrinogen degradation products were detected in 4 of 9 dogs. Despite the degree of vascular endothelial damage evident on fluorescein angiographic and histologic studies in these dogs, plasma TXB2 and 6-keto-PGF1 alpha concentrations were not increased.
Davidson
M G
MG
Department of Companion Animal and Special Species Medicine, College of Veterinary Medicine, North Carolina State University, Raleigh 27606.
Breitschwerdt
E B
EB
Walker
D H
DH
Levy
M G
MG
Carlson
C S
CS
Hardie
E M
EM
Grindem
C A
CA
Nasisse
M P
MP
D015121:6-Ketoprostaglandin F1 alpha / Q000097:blood*; D000818:Animals; D001777:Blood Coagulation; D002199:Capillary Permeability; D004285:Dogs; D005260:Female; D007958:Leukocyte Count / Q000662:veterinary; D008297:Male; D010976:Platelet Count / Q000662:veterinary; D011859:Radiography; D012160:Retina / Q000000981:diagnostic imaging; D012161:Retinal Artery; D012284:Rickettsia rickettsii; D012373:Rocky Mountain Spotted Fever / Q000097:blood / Q000662:veterinary*; D013929:Thromboxane B2 / Q000097:blood*
D013929:Thromboxane B2; D015121:6-Ketoprostaglandin F1 alpha