Doxycycline clearance of experimentally induced chronic Ehrlichia canis infection in dogs.

Abstract

BACKGROUND:

Ineffective clearance of Ehrlichia canis after doxycycline administration has been reported despite the fact that the recommended treatment for canine ehrlichiosis is doxycycline. The effectiveness of doxycycline in clearing E canis infection from the blood and tissues of dogs requires additional evaluation.

HYPOTHESIS:

Doxycycline (5 mg/kg PO q12h), administered for 4 weeks, will eliminate E canis infection from the blood and tissues of experimentally infected dogs.

ANIMALS:

Fifteen Walker hound-mixed breed dogs were inoculated subcutaneously with E canis-infected canine histiocytic cells 4 months before doxycycline treatment.

METHODS:

Four dogs were treated with doxycycline (5 mg/kg PO q12h for 3 weeks), 5 dogs were treated with doxycycline at the same dosage for 4 weeks, and 5 control dogs were not treated. Dexamethasone (0.4 mg/kg i.v.) was given after treatment to precipitate recrudescence of any remaining E canis organisms. Platelet counts, anti-E canis immunofluorescent antibodies, and polymerase chain reaction (PCR) detection of E canis deoxyribonucleic acid (DNA) in blood and tissues were evaluated.

RESULTS:

E canis DNA was not detected in the blood and tissues of doxycycline-treated dogs after treatment. Platelet counts were within reference intervals, and E canis antibodies decreased. Spontaneous clearance of E canis infection occurred in 2 of 5 control dogs. Three control dogs had E canis DNA detected in blood and tissues, platelet counts remained low or within the reference interval, and E canis antibodies remained high.

CONCLUSIONS AND CLINICAL IMPORTANCE:

As administered in this study, doxycycline cleared E canis from the blood and tissues of experimentally infected dogs.

• Authors: S M Eddlestone, P P V P Diniz, T M Neer, S D Gaunt, R Corstvet, D Cho, G Hosgood, B Hegarty, E B Breitschwerdt
• Journal: Journal of veterinary internal medicine (J Vet Intern Med) 2007 Nov-Dec Vol. 21 Issue 6 Pg. 1237-42 ISSN: 0891-6640 [Print] United States
• PMID: 18196732 (Publication Type: Journal Article, Randomized Controlled Trial, Research Support, Non-U.S. Gov't)

Chemical References

• Anti-Bacterial Agents
• Doxycycline

Topics

• Animals
• Anti-Bacterial Agents (therapeutic use)
• Chronic Disease
• Dog Diseases (drug therapy)
• Dogs
• Doxycycline (therapeutic use)
• Ehrlichia canis
• Ehrlichiosis (drug therapy, veterinary)