Title: Brucella canis

{{Short description|Species of bacterium}}
{{Speciesbox
| image = Brucella canis.jpg
| image_alt = Gram-stained photomicrograph depicting numerous Gram-negative &quot;Brucella canis&quot; bacteria
| image_caption = [[Gram-stain]]ed photomicrograph depicting numerous [[gram-negative bacteria|gram-negative]] ''Brucella canis'' bacteria
| status = 
| status_system = 
| status_ref = 
| genus = Brucella
| species = canis
| authority = Carmichael &amp; Bruner, 1968
| synonyms = 
| synonyms_ref = 
}}

'''''Brucella canis''''' is a [[gram-negative bacteria|Gram-negative]] [[bacterium]] in the family [[Brucellaceae]] that causes [[brucellosis]] in [[dog|dogs]], other [[Canidae|canids]], and in rare cases, humans.&lt;ref name=&quot;:13&quot; /&gt; It is a [[Non-motile bacteria|non-motile]] short-rod or coccus-shaped organism, and is [[oxidase]], [[catalase]], and [[urease]] positive.&lt;ref name=&quot;:0&quot; /&gt;  ''B. canis'' causes infertility in both male and female dogs. It can also cause inflammation in the eyes.  The hosts of ''B. canis'' ranges from domestic animals to foxes and coyotes.&lt;ref name=&quot;pmid36014002&quot;&gt;{{cite journal |vauthors=Kurmanov B, Zincke D, Su W, Hadfield TL, Aikimbayev A, Karibayev T, Berdikulov M, Orynbayev M, Nikolich MP, Blackburn JK |date=August 2022 |title=Assays for Identification and Differentiation of Brucella Species: A Review |url= |journal=Microorganisms |volume=10 |issue=8 |page=1584 |doi=10.3390/microorganisms10081584 |pmc=9416531 |pmid=36014002 |doi-access=free}}&lt;/ref&gt; It is a [[Zoonosis|zoonotic]] organism, meaning it is able to be passed from animals to humans.&lt;ref name=&quot;:4&quot; /&gt; It is passed from species to species via bodily fluids such as genital secretions and urine.&lt;ref name=&quot;:7&quot; /&gt; Treatments such as spaying, neutering, and long-term antibiotics have been used to combat ''B. canis'' in dogs''.'' The species was first described in the United States in 1966 where mass abortions of [[beagle]]s were documented.&lt;ref name=&quot;:0&quot; /&gt; ''Brucella canis'' can be found in both pets and wild animals and lasts the lifespan of the animal it has affected.&lt;ref name=&quot;pmid36014002&quot;/&gt; ''B. canis'' has two distinct circular chromosomes that can attribute to horizontal gene transfer.&lt;ref name=&quot;:1&quot;&gt;{{Cite journal |last1=Suárez-Esquivel |first1=Marcela |last2=Chaves-Olarte |first2=Esteban |last3=Moreno |first3=Edgardo |last4=Guzmán-Verri |first4=Caterina |date=2020-10-20 |title=Brucella Genomics: Macro and Micro Evolution |journal=International Journal of Molecular Sciences |language=en |volume=21 |issue=20 |pages=7749 |doi=10.3390/ijms21207749 |doi-access=free |issn=1422-0067 |pmc=7589603 |pmid=33092044}}&lt;/ref&gt;

== Morphology ==
''Brucella canis'' are non-motile organisms and cannot move independently due to the absence of [[Flagellum|flagella]]. Brucella are also non-[[Bacterial capsule|encapsulated]], non-spore forming bacteria that replicate in the [[Endoplasmic reticulum|ER]] of their host cells.&lt;ref&gt;{{Cite journal |last1=González-Espinoza |first1=Gabriela |last2=Arce-Gorvel |first2=Vilma |last3=Mémet |first3=Sylvie |last4=Gorvel |first4=Jean-Pierre |date=2021-02-09 |title=Brucella: Reservoirs and Niches in Animals and Humans |journal=Pathogens |volume=10 |issue=2 |page=186 |doi=10.3390/pathogens10020186 |issn=2076-0817 |pmc=7915599 |pmid=33572264|doi-access=free }}&lt;/ref&gt; The bacteria  are Gram-negative coccobacilli or short rods measuring 0.6 to 1.5 μm long, and 0.5 to 0.7 μm wide, do not have a capsule, do not form spores, and are aerobic.&lt;ref name=&quot;:2&quot;&gt;{{Cite journal |last1=Khairullah |first1=Aswin Rafif |last2=Kurniawan |first2=Shendy Canadya |last3=Puspitasari |first3=Yulianna |last4=Aryaloka |first4=Suhita |last5=Silaen |first5=Otto Sahat Martua |last6=Yanestria |first6=Sheila Marty |last7=Widodo |first7=Agus |last8=Moses |first8=Ikechukwu Benjamin |last9=Effendi |first9=Mustofa Helmi |last10=Afnani |first10=Daniah Ashri |last11=Ramandinianto |first11=Sancaka Chasyer |last12=Hasib |first12=Abdullah |last13=Riwu |first13=Katty Hendriana Priscilia |date=2024-05-31 |title=Brucellosis: Unveiling the complexities of a pervasive zoonotic disease and its global impacts |journal=Open Veterinary Journal |volume=14 |issue=5 |pages=1081–1097 |doi=10.5455/OVJ.2024.v14.i5.1 |issn=2218-6050 |pmc=11199761 |pmid=38938422}}&lt;/ref&gt; 

On blood or chocolate agar, colonies are small (~0.5-2 mm after 48-72 hours), convex, non-hemolytic and non-pigmented. Often ''B. canis'' colonies can present themselves as rough variants, a reflection of their naturally rough lipopolysaccharide ([[Lipopolysaccharide|LPS]]) phenotype.&lt;ref name=&quot;:9&quot;&gt;{{Cite journal |last1=Di Bonaventura |first1=Giovanni |last2=Angeletti |first2=Silvia |last3=Ianni |first3=Andrea |last4=Petitti |first4=Tommasangelo |last5=Gherardi |first5=Giovanni |date=2021-12-14 |title=Microbiological Laboratory Diagnosis of Human Brucellosis: An Overview |journal=Pathogens (Basel, Switzerland) |volume=10 |issue=12 |page=1623 |doi=10.3390/pathogens10121623 |doi-access=free |issn=2076-0817 |pmc=8709366 |pmid=34959578}}&lt;/ref&gt; The optimal growth temperature for ''B. canis'' is 37°C, but growth is still possible within the range from 20°C to 40°C. Additionally, the pH range in which ''B. canis'' grows most effectively is from pH 6.6-7.4, making this organism neutrophilic in nature.&lt;ref name=&quot;:2&quot; /&gt;

Brucella species, specifically ''B. canis,'' possess a highly specialized outer cell envelope characterized by an atypical profile of membrane lipids. Their outer membrane contains very-long-chain fatty acids ([[Very long chain fatty acid|VLCFAs]]) and modified lipid A structures that differ markedly from traditional Gram-negative bacteria.&lt;ref&gt;{{Cite journal |last1=Alakavuklar |first1=Melene A. |last2=Fiebig |first2=Aretha |last3=Crosson |first3=Sean |date=2023-09-15 |title=The Brucella Cell Envelope |journal=Annual Review of Microbiology |volume=77 |pages=233–253 |doi=10.1146/annurev-micro-032521-013159 |issn=1545-3251 |pmc=10787603 |pmid=37104660}}&lt;/ref&gt; Importantly, ''B. canis'' is a &quot;natural rough&quot; ''Brucella.'' Its [[Lipopolysaccharide]] lacks the O-polysaccharide that is present in smooth strains; an envelope trait that influences colony phenotype and host interaction without implying [[Avirulent|a-virulence]].&lt;ref&gt;{{Cite journal |last1=Stranahan |first1=Lauren W. |last2=Arenas-Gamboa |first2=Angela M. |date=2021-07-15 |title=When the Going Gets Rough: The Significance of Brucella Lipopolysaccharide Phenotype in Host–Pathogen Interactions |journal=Frontiers in Microbiology |language=English |volume=12 |article-number=713157 |doi=10.3389/fmicb.2021.713157 |pmid=34335551 |pmc=8319746 |doi-access=free |issn=1664-302X}}&lt;/ref&gt;

''B. canis'' is also unique from other ''Brucella'' species in that they demonstrate a distinctive phospholipid arrangement that differ greatly from other Gram-negative bacteria. Their envelope incorporates uncommon lipid species such as altered [[phosphatidylethanolamine]] and [[lipid A]] derivatives enriched with long-chain and branched fatty acids; features that reflect evolutionary adaptation to an intracellular lifecycle. &lt;ref&gt;{{Cite journal |last1=Alakavuklar |first1=Melene A. |last2=Fiebig |first2=Aretha |last3=Crosson |first3=Sean |date=2023-09-15 |title=The Brucella Cell Envelope |journal=Annual Review of Microbiology |volume=77 |pages=233–253 |doi=10.1146/annurev-micro-032521-013159 |issn=1545-3251 |pmc=10787603 |pmid=37104660}}&lt;/ref&gt; Additionally, its phospholipid portion is mainly composed of [[Vaccenic acid|cis-vaccenic]] cyclopropane with small amounts of [[Lactobacillic acid|lactobaccilic]] acid. This differs from other ''Brucella'' species, as they demonstrate the opposite composition, with lactobacillic acid making up the majority of the phospholipid fraction. ''Brucella'' is unusual in this composition because lactobacillic acid is typically within Gram-positive organisms but not common within Gram-negative organisms such as ''Brucella''.&lt;ref name=&quot;:3&quot;&gt;{{Cite book |last=Bergey |first=David Hendricks |url=https://books.google.com/books?id=9cwgo-9IyTUC&amp;q=brucella+canis&amp;pg=PR9 |title=Bergey's Manual of Systematic Bacteriology |date=2001 |publisher=Springer Science &amp; Business Media |isbn=978-0-387-24145-6 |language=en}}&lt;/ref&gt; These specific envelope features are discussed alongside the organisms hallmark intracellular cycle. After uptake, ''Brucella'' replicate within [[Endoplasmic reticulum|ER-derived]] ''Brucella'' containing vacuoles, a niche specific to replication and survival within ''B. canis''.&lt;ref&gt;{{Cite journal |last=Celli |first=Jean |date=2019-03-08 |title=The Intracellular Life Cycle of Brucella spp |journal=Microbiology Spectrum |volume=7 |issue=2 |pages=10.1128/microbiolspec.bai–0006–2019 |article-number=7.2.07 |doi=10.1128/microbiolspec.bai-0006-2019 |pmc=6448592 |pmid=30848234}}&lt;/ref&gt;

=== Identification ===
''B. canis'' is a [[Zoonosis|zoonotic organism]]. The bacteria are [[oxidase]], [[catalase]] and [[urease]] positive and non-motile. Unlike [[haemophilus]], which they resemble, they have no requirements for added X ([[hemin]]) and V ([[nicotinamide adenine dinucleotide]]) factors in cultures. Full identification is established by [[serology]] and [[Polymerase chain reaction|PCR]]. Due to ''B. canis'' being naturally rough (lacking O-polysaccharide), smooth-antigen serology is unreliable. Modern practice uses ''B. canis''-adapated serological assays such as RSAT/2-ME, IFAT (Immunofluorescence Antibody test) and [[ELISA]] to make full identification.&lt;ref name=&quot;:7&quot;&gt;{{Cite journal |last1=Santos |first1=Renato L. |last2=Souza |first2=Tayse D. |last3=Mol |first3=Juliana P. S. |last4=Eckstein |first4=Camila |last5=Paíxão |first5=Tatiane A. |date=2021-03-02 |title=Canine Brucellosis: An Update |journal=Frontiers in Veterinary Science |language=English |volume=8 |article-number=594291 |doi=10.3389/fvets.2021.594291 |pmid=33738302 |pmc=7962550 |doi-access=free |issn=2297-1769}}&lt;/ref&gt; ''B. canis'' is not acid-fast, but they tend to maintain their color when exposed to weak acids. This results in their red color when stained.&lt;ref&gt;{{Cite web |last=Spickler |first=Anna Rovid |date=2018 |title=Brucellosis: Canine Brucellosis |url=http://www.cfsph.iastate.edu/DiseaseInfo/factsheets.php }}&lt;/ref&gt; When isolated, ''B. canis'' is always in a rough form, with hydrophobic LPS imbedded in its outer membrane. [[MALDI-TOF]] mass spectrometry with validated databases and whole-genome sequencing (WGS) are now increasingly used for definitive confirmation of ''B. canis'' and specific outbreak tracing.&lt;ref&gt;{{Cite journal |last1=da Silva |first1=David Attuy Vey |last2=Brendebach |first2=Holger |last3=Grützke |first3=Josephine |last4=Dieckmann |first4=Ralf |last5=Soares |first5=Rodrigo Martins |last6=de Lima |first6=Julia Teresa Ribeiro |last7=Keid |first7=Lara Borges |last8=Hofreuter |first8=Dirk |last9=Al Dahouk |first9=Sascha |date=2020-11-06 |title=MALDI-TOF MS and genomic analysis can make the difference in the clarification of canine brucellosis outbreaks |journal=Scientific Reports |language=en |volume=10 |issue=1 |page=19246 |doi=10.1038/s41598-020-75960-3 |pmid=33159111 |pmc=7648634 |bibcode=2020NatSR..1019246D |issn=2045-2322}}&lt;/ref&gt;

Colonies of ''Brucella'' can typically start to be seen after 48 hours. These colonies tend to be 0.5-1.0 mm in diameter, with a convex shape and are typically circular. Growth is often slower than other bacteria, with colonies requiring up to 72 hours for clear visualization.&lt;ref name=&quot;:9&quot; /&gt; ''B. canis'' presents itself as a rough species, so colonies are generally non-mucoid rather than sticky, glue-like of presenting smooth strains. Their colonies are small, white to yellowish white and non-pigmented, consistent with rough ''Brucella''.&lt;ref name=&quot;:7&quot; /&gt;

=== Metabolism ===
''B. canis'' functions as a chemoorganotroph, deriving energy from the oxidation of organic compounds and utilizing organic electron sources. Studies indicate that ''B. canis'', like other ''Brucella'' species, shares a conserved metabolic architecture within the genus. This includes a lack of phosphofructokinase (PFK), an enzyme required for the Embden–Meyerhof–Parnas (EMP) pathway (classical glycolysis). Instead, glucose catabolism is accomplished using the pentose phosphate pathway.&lt;ref name=&quot;:9&quot; /&gt; While select ''Brucella'' species can also rely on a functional Entner–Doudoroff pathway, this pathway is not functional in most ''Brucella'' species, including ''B. canis'', due to inactivating mutations.&lt;ref&gt;{{Cite journal |last1=Machelart |first1=Arnaud |last2=Willemart |first2=Kevin |last3=Zúñiga-Ripa |first3=Amaia |last4=Godard |first4=Thibault |last5=Plovier |first5=Hubert |last6=Wittmann |first6=Christoph |last7=Moriyón |first7=Ignacio |last8=De Bolle |first8=Xavier |last9=Van Schaftingen |first9=Emile |last10=Letesson |first10=Jean-Jacques |last11=Barbier |first11=Thibault |date=2020-10-20 |title=Convergent evolution of zoonotic Brucella species toward the selective use of the pentose phosphate pathway |journal=Proceedings of the National Academy of Sciences of the United States of America |volume=117 |issue=42 |pages=26374–26381 |doi=10.1073/pnas.2008939117 |doi-access=free |issn=1091-6490 |pmc=7584911 |pmid=33020286 |bibcode=2020PNAS..11726374M }}&lt;/ref&gt; ''B. canis'' also possesses a complete tricarboxylic acid (TCA) cycle, which primarily utilizes oxygen as its terminal electron acceptor within its electron transport chain. In anaerobic conditions, nitrate can also function as a terminal electron acceptor because ''B. canis'' is capable of producing nitrate reductase.&lt;ref&gt;{{Cite journal |last1=Freddi |first1=Luca |last2=de la Garza-García |first2=Jorge A. |last3=Al Dahouk |first3=Sascha |last4=Occhialini |first4=Alessandra |last5=Köhler |first5=Stephan |date=2023-10-26 |title=Brucella spp. are facultative anaerobic bacteria under denitrifying conditions |journal=Microbiology Spectrum |volume=11 |issue=6 |pages=e02767–23 |doi=10.1128/spectrum.02767-23 |pmc=10714718 |pmid=37882559}}&lt;/ref&gt;

''B. canis'' also exhibits strong urease activity, producing the enzyme urease to hydrolyze urea into ammonia and carbon dioxide. This enzymatic activity is relevant for its role in nitrogen acquisition and as a notable virulence factor, as it helps to neutralize and facilitate survival within surrounding acidic environments.&lt;ref&gt;{{Cite journal |last1=Occhialini |first1=Alessandra |last2=Hofreuter |first2=Dirk |last3=Ufermann |first3=Christoph-Martin |last4=Al Dahouk |first4=Sascha |last5=Köhler |first5=Stephan |date=2022-04-14 |title=The Retrospective on Atypical Brucella Species Leads to Novel Definitions |journal=Microorganisms |language=en |volume=10 |issue=4 |pages=813 |doi=10.3390/microorganisms10040813 |doi-access=free |issn=2076-2607 |pmc=9025488 |pmid=35456863}}&lt;/ref&gt;

For laboratory identification, a relevant metabolic characteristic of ''B. canis'' is that it does not require supplemental {{CO2}} for growth, unlike some other ''Brucella'' species. Additionally, ''B. canis'' has demonstrated growth on media containing thionine, but no growth on media containing basic fuchsin.&lt;ref&gt;{{Cite journal |last1=Massis |first1=Fabrizio De |last2=Sacchini |first2=Flavio |last3=Petrini |first3=Antonio |last4=Bellucci |first4=Fabio |last5=Perilli |first5=Margherita |last6=Garofolo |first6=Giuliano |last7=Savini |first7=Giovanni |last8=Tittarelli |first8=Manuela |date=2023-01-09 |title=Canine brucellosis due to Brucella canis: description of the disease and control measures |url=https://www.veterinariaitaliana.izs.it/index.php/VetIt/article/view/2561 |journal=Veterinaria Italiana |language=en |volume=58 |issue=1 |pages=5–23 |doi=10.12834/VetIt.2561.16874.1 |pmid=35766163 |issn=1828-1427}}&lt;/ref&gt;

=== Genome ===
''B. canis'' has two distinct circular chromosomes, a structure conserved across the ''Brucella'' genus. For the reference strain ATCC 23365, Chromosome 1 has 2,199 genes, and Chromosome 2 has 1,224 genes. These two circular chromosomes contain multiple distinct shared regions, which can be attributed to horizontal gene transfer.&lt;ref name=&quot;:1&quot; /&gt; Evidence suggests that Chromosome 2 was derived from a plasmid, though both chromosomes contain essential genes.&lt;ref name=&quot;:9&quot; /&gt;

''B. canis'' and ''B. suis'' in particular share extremely similar genomic content, exceeding what would traditionally be expected from similarities between different species in the same genus. Genomic analysis suggests that ''B. canis'' is part of the ''B. suis'' clade, and represents a host-adapted variant of ''B. suis''.&lt;ref&gt;{{Cite journal |last1=Whatmore |first1=Adrian M. |last2=Koylass |first2=Mark S. |last3=Muchowski |first3=Jakub |last4=Edwards-Smallbone |first4=James |last5=Gopaul |first5=Krishna K. |last6=Perrett |first6=Lorraine L. |date=2016 |title=Extended Multilocus Sequence Analysis to Describe the Global Population Structure of the Genus Brucella: Phylogeography and Relationship to Biovars |journal=Frontiers in Microbiology |volume=7 |pages=2049 |doi=10.3389/fmicb.2016.02049 |doi-access=free |issn=1664-302X |pmc=5174110 |pmid=28066370}}&lt;/ref&gt; Despite this significant similarity, it is still possible to differentiate between ''B. canis'' and ''B. suis'' using PCR assays targeting specific known genetic variations.&lt;ref name=&quot;:12&quot;&gt;{{Cite journal |last1=Kurmanov |first1=Berzhan |last2=Zincke |first2=Diansy |last3=Su |first3=Wanwen |last4=Hadfield |first4=Ted L. |last5=Aikimbayev |first5=Alim |last6=Karibayev |first6=Talgat |last7=Berdikulov |first7=Maxat |last8=Orynbayev |first8=Mukhit |last9=Nikolich |first9=Mikeljon P. |last10=Blackburn |first10=Jason K. |date=2022-08-06 |title=Assays for Identification and Differentiation of Brucella Species: A Review |journal=Microorganisms |language=en |volume=10 |issue=8 |pages=1584 |doi=10.3390/microorganisms10081584 |doi-access=free |issn=2076-2607 |pmc=9416531 |pmid=36014002}}&lt;/ref&gt; The most notable distinguishing factor is the lack of O-polysaccharide in its lipopolysaccharide, causing the naturally &quot;rough&quot; phenotype for ''B. canis'' in contrast to ''B. suis'' which retains the naturally &quot;smooth&quot; phenotype.&lt;ref&gt;{{Cite journal |last1=Stranahan |first1=Lauren W. |last2=Arenas-Gamboa |first2=Angela M. |date=2021 |title=When the Going Gets Rough: The Significance of Brucella Lipopolysaccharide Phenotype in Host-Pathogen Interactions |journal=Frontiers in Microbiology |volume=12 |article-number=713157 |doi=10.3389/fmicb.2021.713157 |doi-access=free |issn=1664-302X |pmc=8319746 |pmid=34335551}}&lt;/ref&gt;

[[File:PIXNIO-38568-4206x3153.jpg|thumb|269x269px|Image of ''B. canis'' colonies growing on blood agar culture media.]]

==Pathogenicity ==
The disease is characterized by [[epididymitis]] and [[orchitis]] in male dogs, [[endometritis]], [[placentitis]], and [[abortion]]s in females, and often presents as [[infertility]] in both sexes. Other symptoms such as inflammation in the eyes and axial and appendicular skeleton; [[lymphadenopathy]] and [[splenomegaly]], are less common.&lt;ref name=&quot;:9&quot; /&gt;  Although there has been an increase in the international movement of dogs, ''Brucella canis'' is still very uncommon.&lt;ref name=&quot;:0&quot;&gt;{{cite journal |last1=Cosford |first1=Kevin L. |title=Brucella canis: An update on research and clinical management |journal=The Canadian Veterinary Journal |date=2018 |volume=59 |issue=1 |pages=74–81 |pmc=5731389 |pmid=29302106 }}&lt;/ref&gt; Signs of this disease are different in both genders of dogs; females that have ''B. canis'' infections face an abortion of their developed fetuses. Males face the chance of infertility, because they develop an antibody against their spermatozoa. This may be followed by inflammation of the testes which generally settles down a while after. Another symptom is the infection of the spinal plates or [[vertebrae]], which is called [[spondylitis|diskospondylitis]].&lt;ref name=&quot;pmid31814636&quot;&gt;{{cite journal |vauthors=Forbes JN, Frederick SW, Savage MY, Cross AR |title=Brucella canis sacroiliitis and discospondylitis in a dog |journal=The Canadian Veterinary Journal |volume=60 |issue=12 |pages=1301–1304 |date=December 2019 |pmid=31814636 |pmc=6855227 |doi= |url=}}&lt;/ref&gt; It is generally spotted in the animal's reproductive organs. This infection usually causes the animal to spontaneously abort a fetus and can also cause an animal to become sterile.&lt;ref&gt;[https://www.nj.gov/health/cd/documents/topics/Brucellosis/Canine%20Brucellosis%20Fact%20Sheet-%20general%20public-%20NJDOH.pdf Canine Brucellosis: Facts for Dog Owners]&lt;/ref&gt;

=== Host range ===
The host range of the bacterium is mainly domestic dogs but evidence of infections in foxes and coyotes has been reported.&lt;ref name=&quot;:9&quot; /&gt; ''B. canis'' is a [[Zoonosis|zoonotic organism]]&lt;ref name=&quot;pmid31814636&quot; /&gt;  and although rare, humans can contract the infection. It is unlikely, but most common in dog breeders, those in laboratories dealing with the bacteria, or people who are immunocompromised.&lt;ref name=&quot;:8&quot; /&gt;

=== Transmission ===
''B. canis'' is commonly transmitted during sexual intercourse, as well as physical contact with infected bodily fluids.&lt;ref name=&quot;:7&quot; /&gt; ''B. canis'' is passed through contact with fluids from the [[Mucous membrane|mucous membranes]] of the genitals (semen and vaginal discharge), eyes, and oronasal cavities. The highest bacterial loads of ''B. canis'' are found in the genital secretions of dogs infected with the bacteria.&lt;ref name=&quot;:7&quot; /&gt; Contact can occur during sexual activity as well as other daily grooming and social interactions. Though dog-to-dog transmission is most commonly during breeding, it can also happen after contact with uterine discharge, semen, and aborted material.&lt;ref name=&quot;:7&quot; /&gt;

High levels of ''B. canis'' exist in these secretions in the six weeks following abortion in females, and around six to eight weeks following infection in males. Lower levels of ''B. canis'' still remain in the semen of infected males for two years following infection, which can serve as a large source of transmission to other dogs.&lt;ref name=&quot;:0&quot; /&gt; Offspring of infected females can be infected with ''B. canis'' through intrauterine vertical transmission or via drinking the milk of the infected female.&lt;ref name=&quot;:7&quot; /&gt;

Urine can also serve as a route of transmission in males, as the bladder resides in close proximity to the prostate and epididymus. The bacterial load in the urine of infected dogs is lower than in genital discharges.&lt;ref name=&quot;:6&quot;&gt;{{Cite journal |last1=van Dijk |first1=Marloes A.M. |last2=Engelsma |first2=Marc Y. |last3=Visser |first3=Vanessa X.N. |last4=Keur |first4=Ingrid |last5=Holtslag |first5=Marjolijn E. |last6=Willems |first6=Nicole |last7=Meij |first7=Björn P. |last8=Willemsen |first8=Peter T.J. |last9=Wagenaar |first9=Jaap A. |last10=Roest |first10=Hendrik I.J. |last11=Broens |first11=Els M. |date=July 2021 |title=Transboundary Spread of Brucella canis through Import of Infected Dogs, the Netherlands, November 2016–December 2018 |url=https://wwwnc.cdc.gov/eid/article/27/7/20-1238_article.htm |journal=Emerging Infectious Diseases |volume=27 |issue=7 |pages=1783–1788 |doi=10.3201/eid2707.201238 |issn=1080-6040 |pmc=8237882 |pmid=34152959}}&lt;/ref&gt; In their urine, infected dogs can carry up to 10&lt;sup&gt;6&lt;/sup&gt; bacteria per milliliter, compared to the genital discharges that can carry up to 10&lt;sup&gt;10&lt;/sup&gt; bacteria per milliliter.&lt;ref name=&quot;:6&quot; /&gt; This leads to contamination of the urine making it another vehicle for ''B. canis'' transmission.&lt;ref name=&quot;:6&quot; /&gt; Infected dogs carry the highest bacterial load of ''B. canis'' after 1-6 months after infection.&lt;ref name=&quot;:6&quot; /&gt; Infected neutered animals are not able to display reproductive symptoms, however both intact and neutered dogs are able to shed ''B. canis'' in urine.&lt;ref name=&quot;:6&quot; /&gt; This means that both neutered and intact dogs are able to transmit the disease via urine.&lt;ref name=&quot;:6&quot; /&gt; ''B. canis'' is found to be localized in the prostate of male dogs, thus transmitting through the urine in both intact and neutered males.&lt;ref name=&quot;:6&quot; /&gt; It has been suggested that male dogs carry higher concentrations of the bacteria when compared to female dogs due contamination from seminal fluid.&lt;ref name=&quot;:4&quot;&gt;{{Cite journal |last1=Hensel |first1=Martha E. |last2=Negron |first2=Maria |last3=Arenas-Gamboa |first3=Angela M. |date=August 2018 |title=Brucellosis in Dogs and Public Health Risk |volume=24 |issue=8 |journal=Emerging Infectious Diseases Journal |pages=1401–1406 |publisher=CDC |url=https://wwwnc.cdc.gov/eid/article/24/8/17-1171_article |language=en-us |doi=10.3201/eid2408.171171|pmid=30014831 |pmc=6056133 }}&lt;/ref&gt; Neutered dogs are also capable of shedding the bacteria in their saliva and nasal secretions.&lt;ref name=&quot;:4&quot; /&gt;

''B. canis'' is the least common cause of [[Brucellosis]] in humans.&lt;ref name=&quot;:10&quot;&gt;{{Cite web |last=CDC |date=2025-09-08 |title=Clinical Overview of Brucellosis |url=https://www.cdc.gov/brucellosis/hcp/clinical-overview/index.html |access-date=2025-11-25 |website=Brucellosis |language=en-us}}&lt;/ref&gt; Transmission to humans is rarely diagnosed but is possible.&lt;ref&gt;{{Cite journal |last1=Dentinger |first1=C. M. |last2=Jacob |first2=K. |last3=Lee |first3=L. V. |last4=Mendez |first4=H. A. |last5=Chotikanatis |first5=K. |last6=McDonough |first6=P. L. |last7=Chico |first7=D. M. |last8=De |first8=B. K. |last9=Tiller |first9=R. V. |last10=Traxler |first10=R. M. |last11=Campagnolo |first11=E. R. |last12=Schmitt |first12=D. |last13=Guerra |first13=M. A. |last14=Slavinski |first14=S. A. |date=2015 |title=Human Brucella canis Infection and Subsequent Laboratory Exposures Associated with a Puppy, New York City, 2012 |journal=Zoonoses and Public Health |language=en |volume=62 |issue=5 |pages=407–414 |doi=10.1111/zph.12163 |issn=1863-2378 |pmc=4639931 |pmid=25363807}}&lt;/ref&gt; It can be transmitted via bodily fluids and aborted material.&lt;ref name=&quot;:11&quot;&gt;{{Cite journal |last=Moore |first=Tori S. |date=2024 |title=Notes from the Field: Multidisciplinary Approach to Investigating Brucella canis Exposures — South Carolina, September 2023 |url=https://www.cdc.gov/mmwr/volumes/73/wr/mm7325a3.htm |journal=MMWR. Morbidity and Mortality Weekly Report |language=en-us |volume=73 |issue=25 |pages=581–582 |doi=10.15585/mmwr.mm7325a3 |pmid=38935566 |pmc=11254343 |issn=0149-2195}}&lt;/ref&gt; Signs and symptoms are very non-specific, such as fever, joint pain, and fatigue.&lt;ref name=&quot;:11&quot; /&gt; The disease can also be debilitating, causing conditions such as [[endocarditis]], [[splenomegaly]], or [[Neurological symptoms|neurologic symptoms]].&lt;ref name=&quot;:11&quot; /&gt;   

=== Diagnosis and Treatment ===
In current practice for dogs, ''B. canis'' is diagnosed using [[Polymerase chain reaction|PCR]], [[Microbiological culture|cultures]], and [[Serological testing|serologic testing]].&lt;ref name=&quot;:4&quot; /&gt; The most standard test for ''B. canis'' is culture.&lt;ref name=&quot;:4&quot; /&gt; These cultures are typically conducted on the host's blood, vaginal discharge, or semen.&lt;ref name=&quot;:4&quot; /&gt; However, this method is not effective if the dog has been treated with [[Antimicrobial|antimicrobial drugs]], as this will clear ''B. canis'' bacteria even if the disease has not resolved.&lt;ref name=&quot;:4&quot; /&gt; Serology is used to evaluate the antibody response against ''Brucella'' spp. cell wall antigens, the downfall of this method is it's lack of specificity.&lt;ref name=&quot;:4&quot; /&gt; PCR testing has shown potential as a rapid test, however it is not readily available and is currently considered an experimental test.&lt;ref name=&quot;:4&quot; /&gt;  

Currently, there are not commercially available vaccines for ''B. canis''.&lt;ref name=&quot;:5&quot;&gt;{{Cite journal |last1=Djokic |first1=Vitomir |last2=Freddi |first2=Luca |last3=de Massis |first3=Fabrizio |last4=Lahti |first4=Elina |last5=van den Esker |first5=Marielle H. |last6=Whatmore |first6=Adrian |last7=Haughey |first7=Anna |last8=Ferreira |first8=Ana Cristina |last9=Garofolo |first9=Giuliano |last10=Melzer |first10=Falk |last11=Sacchini |first11=Flavio |last12=Koets |first12=Ad |last13=Wyllie |first13=Stephen |last14=Fontbonne |first14=Alain |last15=Girault |first15=Guillaume |date=2023-12-08 |title=The emergence of Brucella canis as a public health threat in Europe: what we know and what we need to learn |journal=Emerging Microbes &amp; Infections |volume=12 |issue=2 |article-number=2249126 |doi=10.1080/22221751.2023.2249126 |pmc=10540651 |pmid=37649455}}&lt;/ref&gt; Antimicrobial treatment and [[Sterilization of dogs|sterilization]] of the infected animals is considered an alternative to removing the animal.&lt;ref name=&quot;:5&quot; /&gt; There have been reports of anti-''Brucella'' vaccines (used for cattle and small ruminants), used along with previously mentioned methods but is not considered practical due to its risk of vaccine strain shedding in a domestic environment with current vaccines maintaining an amount of virulence for humans.&lt;ref name=&quot;:5&quot; /&gt; 

Treatment for ''B. canis'' is very difficult to find and often very expensive. This is due to ''B. canis'' being a intracellular bacteria, meaning it replicates inside of host cells rather than outside of them.&lt;ref name=&quot;:5&quot; /&gt; This makes it difficult for antibiotics to reach the bacteria. Different antibiotics have been tried both alone and together, but none are completely effective at eliminating the disease.&lt;ref name=&quot;:5&quot; /&gt; The combination of [[minocycline]] and [[streptomycin]] is thought to be useful, but it is often unaffordable. [[Tetracycline]] can be a less expensive substitute for minocycline, but it also lowers the effect of the treatment.&lt;ref name=&quot;:5&quot; /&gt;

Long term antibiotics can be given but usually results in a relapse. Spaying and neutering can be effective, and frequent blood tests are recommended to monitor progress. Dogs in kennels that are affected by ''B. canis'' are usually euthanized for the protection of other dogs and the humans caring for them.&lt;ref name=&quot;:0&quot; /&gt;

''B. canis'' is relatively easy to prevent in dogs.  Any dog that will be used for breeding or has the capability to breed should be serologically tested before mating.&lt;ref name=&quot;:0&quot; /&gt; All dogs new dogs being introduced to a kennel should be examined for signs of the disease and quarantined before being exposed to other dogs.&lt;ref name=&quot;:0&quot; /&gt;

There are currently no approved serologic tests approved for testing for ''B. canis'' in humans.&lt;ref name=&quot;:11&quot; /&gt; Treatment for human Brucellosis usually includes combination antibiotic treatment for at least 6 weeks.&lt;ref name=&quot;:10&quot; /&gt; Recovery can range from a few weeks to months, however brucellosis rarely causes death in humans (estimated no more than 2% die from infection).&lt;ref name=&quot;:10&quot; /&gt;

=== Ecology ===
Under natural conditions ''Brucella spp'', including ''B. canis'' are [[Obligate parasite|obligate parasites]] and do not grow outside the host except in laboratory cultures. However, at specific temperatures and moisture levels ''Brucella'' can persist in soil and surface water up to 80 days. The bacterium can also survive for months in frozen conditions.&lt;ref name=&quot;pmid29783033&quot;&gt;{{cite journal |vauthors=Xue S, Biondi EG |title=Coordination of symbiosis and cell cycle functions in Sinorhizobium meliloti |journal= Biochimica et Biophysica Acta (BBA) - Gene Regulatory Mechanisms|volume=1862 |issue=7 |pages=691–696 |date=July 2019 |pmid=29783033 |doi=10.1016/j.bbagrm.2018.05.003|s2cid=29166156 |url=https://hal-amu.archives-ouvertes.fr/hal-01916124/file/S1874939917304157.pdf }}&lt;/ref&gt; 

''B. canis'' is mainly found in dogs, but can also affect other wild canine species such as wolves, foxes, and coyotes.&lt;ref&gt;{{Cite journal |last1=Kosoy |first1=Michael |last2=Goodrich |first2=Irina |date=2019-01-04 |title=Comparative Ecology of Bartonella and Brucella Infections in Wild Carnivores |journal=Frontiers in Veterinary Science |language=English |volume=5 |article-number=322 |doi=10.3389/fvets.2018.00322 |doi-access=free |issn=2297-1769 |pmc=6328487 |pmid=30662899}}&lt;/ref&gt; The bacterium persists in these hosts, being an adaptive pathogen towards canines. The environment these hosts reside in further contribute to the canine specificity. Dog kennels are a favored environment for the bacterium to spread due to transmission through urine and reproductive fluids. Movement of infected animals through pet trade or shelter transport also plays a critical role in the broader distribution of the bacterium. In wildlife, ''B. canis'' is also circulated through hunting and scavenging.&lt;ref&gt;{{Cite journal |last1=Pinn-Woodcock |first1=Toby |last2=Frye |first2=Elisha |last3=Guarino |first3=Cassandra |last4=Franklin-Guild |first4=Rebecca |last5=Newman |first5=Alexandra P. |last6=Bennett |first6=Joy |last7=Goodrich |first7=Erin L. |date=2023-04-01 |title=A one-health review on brucellosis in the United States |url=https://avmajournals.avma.org/view/journals/javma/261/4/javma.23.01.0033.xml |journal=Journal of the American Veterinary Medical Association |volume=261 |issue=4 |pages=451–462 |doi=10.2460/javma.23.01.0033 |pmid=36862545 |issn=0003-1488}}&lt;/ref&gt;

Zoonotic transmission to humans is rare but possible, particularly for people in close contact with infected reproductive tissues.&lt;ref name=&quot;:8&quot; /&gt; Certain occupations are at higher risk of exposure to ''B. canis''. These persons include veterinarians, kennel workers, dog breeders, and laboratory personnel.&lt;ref name=&quot;:13&quot;&gt;{{Cite journal |last1=Pinn-Woodcock |first1=Toby |last2=Frye |first2=Elisha |last3=Guarino |first3=Cassandra |last4=Franklin-Guild |first4=Rebecca |last5=Newman |first5=Alexandra P. |last6=Bennett |first6=Joy |last7=Goodrich |first7=Erin L. |title=A one-health review on brucellosis in the United States |url=https://avmajournals.avma.org/view/journals/javma/261/4/javma.23.01.0033.xml |access-date=2025-11-25 |journal=Journal of the American Veterinary Medical Association |date=2023 |volume=261 |issue=4 |pages=451–462 |doi=10.2460/javma.23.01.0033 |pmid=36862545 }}&lt;/ref&gt;

== History ==
''Brucella canis'' was first discovered in the United States by Leland Carmichael in 1966, when the bacterium was identified in canine vaginal discharge and the tissues from mass abortions in beagles.&lt;ref name=&quot;:0&quot; /&gt; ''B. canis'' was said to be a [[biovar]] of ''B. suis.'' With recent research, PCR assay data was able to contradict ''B. canis'' and ''B. suis''. PCR data showed a complete difference between the two strains along with ''B. suis'' biovars unattained from ''B. canis'' DNA. PCR assays have been proven beneficial when differentiating between ''Brucella'' strains and vaccine strains.&lt;ref name=&quot;:12&quot; /&gt;

Investigations into the bacterium revealed that domestic dogs are primarily affected along with other canine species. ''B. canis'' causes reproductive issues in female dogs, usually in the form of late-term spontaneous abortions. While in males, [[epididymitis]], [[orchitis]], and infertility were observed due to the bacterium.&lt;ref name=&quot;:7&quot; /&gt;

During the 1970s and 1980s, ''B. canis'' was reported in North America, Europe, and Asia. The reports were mainly from commercial breeding kennels wherein the bacterium can easily spread.&lt;ref name=&quot;:7&quot; /&gt; Increase in infections were also attributed to the growing adoption of dogs as pets.&lt;ref&gt;{{Cite journal |last1=Sebzda |first1=Mary K. |last2=Kauffman |first2=Lin K. |date=2023-09-01 |title=Update on Brucella canis: Understanding the Past and Preparing for the Future |url=https://www.sciencedirect.com/science/article/pii/S019556162300075X |journal=Veterinary Clinics of North America: Small Animal Practice |series=Small Animal Theriogenology |volume=53 |issue=5 |pages=1047–1062 |doi=10.1016/j.cvsm.2023.05.002 |pmid=37385876 |issn=0195-5616|url-access=subscription }}&lt;/ref&gt; By the 2000s, molecular analysis revealed that ''B. canis'' is unique from other ''Brucella'' species, categorized as a naturally occurring rough species that needs an anti-rough lipopolysaccharide reagent for detection.&lt;ref name=&quot;:8&quot;&gt;{{Cite journal |last1=Weese |first1=J. Scott |last2=Weese |first2=Heather E. |year=2025 |title=Brucellosis in humans caused by Brucella canis: A scoping review |journal=The Canadian Veterinary Journal = la Revue Veterinaire Canadienne |volume=66 |issue=3 |pages=327–334 |issn=0008-5286 |pmc=11891790 |pmid=40070936}}&lt;/ref&gt; 

''B. canis'' has been recognized as a growing zoonotic risk worldwide, having the ability to infect humans. Laboratory exposure or contact with pet dogs that had aborted fetuses were the main sources of exposure to the bacterium.&lt;ref name=&quot;:8&quot; /&gt; Human infections are often underdiagnosed due to limited diagnostic awareness and the overlapping clinical presentation with other ''Brucella'' species, which hinders precise identification.&lt;ref name=&quot;:5&quot; /&gt;&lt;ref name=&quot;:8&quot; /&gt;

==References==
{{Reflist|2}}

==External links==
*[https://web.archive.org/web/20110727165723/http://patricbrc.org/portal/portal/patric/Taxon?cType=taxon&amp;cId=36855 ''Brucella canis''] genomes and related information at [http://patricbrc.org patricbrc.org], a Bioinformatics Resource Center funded by [https://www.niaid.nih.gov/    NIAID]

{{Taxonbar|from=Q4978547}}

{{DEFAULTSORT:Brucella canis}}
[[Category:Dog diseases]]
[[Category:Parasites of dogs]]
[[Category:Bacteria described in 1968]]
[[Category:Hyphomicrobiales]]