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Volume 31, Number 11—November 2025

Research

Isolation and Characterization of Rickettsia finnyi, Novel Pathogenic Spotted Fever Group Rickettsia in Dogs, United States

Praveen K. Korla1, Michael G. Karounos1, Sarah B. Clarke, Cynthia Robveille, James M. Wilson, Edward B. Breitschwerdt, Adam J. Birkenheuer, and Barbara A. QurolloComments to Author 
Author affiliation: North Carolina State University College of Veterinary Medicine, Raleigh, North Carolina, USA

Main Article

Table 2

Date, location, signalment, and vectorborne disease diagnostic results from dogs naturally infected with Rickettsia finnyi sp. nov. strain 2024-CO-Wats in study of isolation and characterization of novel pathogenic spotted fever group Rickettsia in dogs, United States*

Dog no. Date State Breed Age, y/sex Rickettsia 23S-5S ITS PCR (Cq, Mt)† R. rickettsii IFA titer Vectorborne disease co-infections, test type (titer)
1‡
 2018 May 17
 TN
 MB
 10/MC
 37.7, 77.5°
 1:512
 None
2‡ 2019 May 8 IL BT 9/MC 39.1, 78° 1:256 None
2019 May 15§
ND
 1:8,192
3‡ 2019 Aug 28 OK MB 9/MC 33.8, 77.5° 1:1,024 None
2019 Sep 10§
ND
 1:8,192
4 2020 May 3 OK V 8/MC 38.1, 78° 1:256 Ehrlichia SNAP4DxPlus
2020 May 28§
ND
 1:512
5
 2020 May 7
 TX
 MB
 7/MC
 34.5, 77°
 1:512
 Mycoplasma hematoparvum PCR+
6 2020 Jul 16 NC KSD 2/FS 35.4, 77.5° <1:32 Bartonella henselae IFA (1:64)
2020 Aug 19§
ND
 1:1,024
7
 2020 Aug 1
 CO
 ESS
 12/FS
 33.8, 77.5°
 <1:32
 Babesia sp. (Coco) PCR+
8
 2022 May 23
 KS
 LR
 4/MC
 37.7, 77.5°
 1:265
 Ehrlichia SNAP4DxPlus
9 2022 May 24 MO LR 6/M 38.3, 77.5° 1:2,048 None
2022 Jun 17§
ND
 1:8,192
10
 2023 May 5
 KS
 ASP
 3/FS
 33.9, 77.5°
 <1:32
 None
11
 2023 May 5
 KS
 MB
 13/MC
 36.5, 77.5°
 1:4,096
 Anaplasma SNAP4DxPlus, B. canis IFA (1:256),
12 2023 Sep 13 AL MB 8/MC 36.6, 78° 1:512 None
2023 Oct 2§
ND
 1:4,096
13
 2023 Sep 18
 MO
 LR
 8/M
 33.1, 77.5°
 1:256
 None
14 2023 Oct 10 IA GR 5/FS 37.4, 78° 1:64 Ehrlichia SNAP4DxPlus, E. canis IFA (1:64)
2023 Oct 19§
ND
 1:4,096
15¶
 2024 Apr 25
 IN
 MB
 9/M
 28.8, 77°
 1:1,024
 None
16
 2024 Oct 23
 LA
 TP
 4/M
 36.5, 77.5°
 1:2,048
 None
17 2025 May 14 LA MB 8/MC 36.4, 77.5° 1:4,096 None

*ASP, American Staffordshire terrier; BT, Boston terrier; Cq, quantification cycle; ESS, English springer spaniel; FS, female spayed; GR, golden retriever; IFAT, indirect immunofluorescent antibody; ITS, internal transcribed spacer; KSD, Kangal shepherd dog; LR, labrador retriever; MC, male castrated; Mt, melting temperature; MB, mixed breed; ND, not detected; TP, toy poodle; VBD, vectorborne disease; V, Vizsla.
†Rickettsia 23S-5S ITS amplicons were Sanger sequenced and 100% identical to Rickettsia sp. strain 2019-CO-FNY.
‡Dogs described previously (1).
§Post doxycycline treatment.
¶Sample used for culturing.

Main Article

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Main Article

1These authors contributed equally to this article.

Page created: September 24, 2025
Page updated: November 26, 2025
Page reviewed: November 26, 2025
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