Page 1026 - Clinical Small Animal Internal Medicine

964 Section 9 Infectious Disease

discharge may persist in aborting bitches for up to six ancillary testing before the animal is considered to be
VetBooks.ir weeks. Some bitches may have perceived infertility due truly positive.
Agar gel immunodiffusion (AGID) assays are fre-
to early embryonic loss.
Males develop a characteristic epididymitis approxi-
mately five weeks after infection. Increased presence of quently used as the confirmatory test of choice for other
serologic assays, although positive cross‐reactions are
neutrophils and teratozoospermia with sperm agglutina- common. Enzyme‐linked immunosorbent assays
tion is often seen 18 weeks post infection. Over 90% of (ELISAs) detect antibodies to the organism and may be
sperm are morphologically abnormal by week 20 post more rapid and specific than agglutination or AGID
infection. The enlarged epididymis is often painful and assays. Positive dogs can be detected within 30 days of
scrotal dermatitis may also be seen due to increased infection using this test, but current availability of this
licking of the scrotum because of discomfort. Chronic test is limited commercially.
infection often leads to testicular atrophy. Concurrent Most recently, real‐time polymerase chain reaction
prostatitis is common. (PCR) testing has become available as a rapid, sensitive,
Dogs with systemic infection may also present with and specific assay for Brucella species. It also has the
clinical signs outside the reproductive tract, depending benefit of being able to directly detect Brucella canis
on the site of infection. Discospondylitis, lymphadenitis, DNA in blood and tissues. It is likely that PCR will be the
lameness, ataxia, recurrent anterior uveitis, and low‐ diagnostic test of choice in the future as it becomes more
grade meningitis have all been reported in B. canis‐ widely available.
infected animals.

Therapy
Diagnosis
Due to the intracellular location of Brucella bacteria,
Direct detection of the organism in culture remains the antimicrobial treatments are challenging. There is no
only definitive diagnostic method available; however, the vaccine currently available. While it is possible for abort-
slow growth rate, intracellular location, and previous ing females to subsequently carry and produce litters
antibiotic therapy may affect the results. Therefore, a without treatment, infection is likely to be transmitted to
negative culture does not rule out disease. Positive blood offspring and infected dogs remain a risk to other dogs
cultures may occur starting at 2–4 weeks post infection and humans.
up to several years following infection due to intermit- Infected animals should be quarantined and removed
tent shedding of the organism. Placenta, fetus, lymph from the breeding population via surgical sterilization. In
nodes, bone marrow, prostate, spleen, urine, vaginal kennel situations where infected animals are identified,
discharge, and semen may all be potential sites for cul- euthanasia may be recommended to prevent transmis-
ture of organisms. sion of disease and resident animals should be tested
Due to the difficulty in growing the organism in monthly. New animals introduced to the kennel should be
culture, serology can be a helpful screening tool for the isolated until two negative screening tests are obtained at
disease. Antibodies can be detected 3–4 weeks post least 30 days apart. Breeding animals should be screened
infection and serology is most accurate as a screening serologically every six months prior to breeding.
test 8–12 weeks post infection. Serologic testing is highly No single antimicrobial protocol has been shown to con-
sensitive, but has low specificity due to cross‐reactivity sistently eliminate the disease long term. Many believe
with other bacterial species. Serologic tests include the that permanent cures may not be possible even with
rapid slide agglutination test (RSAT), which is available surgical sterilization and antimicrobial treatment.
as a commercial, cage‐side screening test, with or with- Combination protocols with aminoglycosides and tetra-
out the addition of 2‐mercaptoethanol (2‐ME). If a sam- cyclines (gentamicin 5 mg/kg SC q24h for seven days,
ple tests positive with the RSAT test, 2‐ME should be repeated every three weeks for three months, and doxy-
added to prevent cross‐reactivity with IgM antibodies to cycline 10 mg/kg orally q12h), or tetracyclines and strepto-
other bacteria species and increase the specificity of the mycin (tetracycline 30 mg/kg orally q12h for 28 days and
test. A second serologic test, the tube agglutination test streptomycin 20 mg/kg IV q24h for 14 days) show the
(TAT), is similar but is quantitative. Titers less than most success, but even with treatment, titers may reap-
1:200 should be retested approximately two weeks later. pear much later after infection, especially during times
Any positive agglutination test should be validated with of stress. A protocol using twice‐daily oral enrofloxacin