Discussion
Diskospondylitis is an infection of the intervertebral disk and adjacent vertebral bodies. It most commonly affects large-
and giant-breed dogs.1 Males are affected twice as frequently as females.2 The most common clinical sign is spinal pain, which is present in more than 80% of cases.3 Other clinical signs are more variable and include anorexia, weight loss, lethargy, fever, and neurologic deficits.4
Hematogenous spread of organisms from local or systemic infection is thought to be the most common cause of diskospondylitis.1 Conditions that may contribute to diskospondylitis include urogenital tract infections, bacterial endocarditis, periodontal
disease, and skin infections.1,5,6 Other potential sources of infectious organisms include penetrating skin wounds, migrating foreign bodies, vertebral surgery,
and extension of paravertebral infections.1,7-9 A variety of bacterial organisms have been isolated from diskospondylitis lesions; Staphylococcus and Streptococcus species, Escherichia coli, and B. canis have been reported most frequently, and Pasteurella haemolytica, Pseudomonas aeruginosa, and Enterococcus, Nocardia, Actinomyces, Micrococcus, Proteus, and Corynebacterium species have been reported sporadically.7,8,10-12 Rarely, fungal organisms have been identified, including Aspergillus, Fusarium, Mucor, Penicillium, Paecilomyces, Chrysosporium, and Pseudallescheria species.10,13
Brucella canis has been implicated as the causative organism in 12.5% and 10.4% of canine diskospondylitis cases in two studies.4,14
Brucella canis is a small, gram-negative, aerobic coccobacillus.15 It can cause systemic infections in dogs, with a variety of clinical manifestations. These clinical abnormalities are the
result of organism localization within tissues and immune-complex-associated pathology.16 Abortions and infertility resulting from placental infections, orchitis, and epididymitis are the most common clinical abnormalities
associated with infection.17 Enlarged lymph nodes, uveitis, diskospondylitis, osteomyelitis, meningitis, glomerulonephritis, and dermatitis have also
been reported.14,17-20 It is interesting that no clinical signs attributable to the urinary, lymphatic, or reproductive tract were present in this
case, as would be expected in an animal infected with B. canis. Histologic examination of the testes and epididymides confirmed extensive pathology, but no abnormalities were found on
clinical examination.
Brucella canis infection can be transmitted between dogs by several routes. Infections may be acquired by ingestion, by inhalation of aerosolized
organisms, by venereal contact, in utero, and by fomites (e.g. from instruments used during artificial insemination or blood transfusion).15 Organisms can be found in vaginal discharge, seminal fluid, aborted materials, urine, milk, saliva, and nasal secretions
from infected individuals.15,21,22 Natural infection is thought to most commonly occur by oronasal contact with aborted materials.
A diagnosis of B. canis infection carries many important clinical implications. Brucella canis is a potential zoonotic agent. More than 35 human infections with B. canis have been reported in the literature, but people appear relatively resistant to infection, and the disease is typically responsive
to antimicrobial therapy.23,24 The mechanism of B. canis transmission from dogs to people has not been fully elucidated, but it is thought to occur by contact with infected tissues
or body fluids.24 Typical clinical signs in people include fatigue, fever, chills, weight loss, and enlarged lymph nodes.24-26 Rarely, serious complications, such as meningitis, endocarditis, hepatitis, arthritis, osteomyelitis, and visceral abscesses,
may develop.23,27
|
Featuring Information from:
