Chlamydial infections in dogs
The diagnosis of chlamydial infections in dogs
is uncommon, perhaps reflecting a failure to consider chlamydiae as potential causes of disease in this species.
Nevertheless, chlamydiae have been implicated in a number of cases of canine disease (Shewen, 1980).
In early reports, chlamydial agents were isolated from the brains of dogs with
encephalitis (Giroud et al.,
1954; Groulade et al.,
1954; Contini, 1956). A
distemper-like disease syndrome was identified in affected dogs. It presented as a systemic infection,
acute, sub-acute or chronic, with young dogs affected most severely. Clinical signs included fever, bronchopneumonia, peritonitis,
lack of appetite, vomiting, diarrhoea and skin lesions. Rising antibody titres to chlamydiae were
present. Chlortetracycline achieved striking cures, which, in addition to rising
chlamydial antibody titres, distinguished this chlamydial disease from canine distemper. Chlamydiae
were also recovered from cases of conjunctivitis in German Shepherd dogs and other breeds
(Voigt et al., 1966; Scott,
1968).
Antibodies to C. psittaci have been demonstrated in dogs
(Fukushi et al., 1985; Werth et al., 1987). As many as 50% of the sera of asymptomatic, clinically normal
dogs had antibodies to chlamydiae (Terzin and
Miskov, 1965) while Popovici (1966) found chlamydial antibodies in dogs in contact with chlamydial-infected ewes.
Kocianova et al., (1992)
found that almost 50% of canine sera from wild
dogs in Sri Lanka contained antibodies to chlamydiae. [MEW Comment: Given the poor
specificity of serological tests for chlamydiae, the significance of all this is
unclear]. Sixl et al., (1988)
found the highest prevalence of chlamydial antibody in private guard dogs,
some working dogs and strays, dogs although the animals were largely healthy.
A case of Chlamydia-induced septic polyarthritis in a dog was
described by Lamrechts et al.,
(1999), in which systemic disease was associated with fever, swollen lynmph
nodes, plus arthritis in several joints. Chlamydial agents of unknown species were identified in joint fluid. The origin of the infection
was unknown, but
this was considered the first description of a case of canine chlamydial
arthritis.
Like humans, dogs may occasionally be
unusual hosts for avian chlamydiae, becoming infected but rarely transmitting the
infection. Several reports describe dogs acquiring avian chlamydial infections (Fraser et al.,
1969; Fukushi et al.,
1985; Krauss et al., 1988). In the case described by Fraser, a dog and several people contracted
a presumed avian chlamydial infection from budgerigars that died of chlamydiosis in an aviary. The dog developed respiratory signs and a high chlamydial antibody titre, and chlamydial agents were recovered from the faeces of two other contact dogs. In another report, a dog contracted a highly pathogenic chlamydial strain from a turkey
(Arizmendi et al., 1992). Chlamydiae were isolated from pleural effusion in the affected animal.
C. psittaci infection was also identified by Krauss et al.,
(1988) in a case of conjunctivitis in a dog.
Gresham et al., (1996) reported
a remarkable household outbreak of chlamydiosis affecting multiple hosts. Three humans and two of three dogs acquired infection with an avian strain of C. psittaci
two to three weeks after acquiring a new cockatiel [a
psittacine bird]. The bird developed a mild oculo-nasal discharge and C. psittaci DNA was detected by PCR in a
faecal sample. Symptoms in the humans included nausea, lethargy, cramps, fever, headache, photophobia and hallucinations. One person was ill for three months.
Symptoms in the dogs, included acute onset shivering, coughing, retching, dyspnoea and
fever plus a slight oculo-nasal discharge. C. psittaci DNA was detected by PCR in one of the affected dogs. The people and the dogs were treated with antibiotics, and the cockatiel was
killed [ ] on the grounds that it presented a significant risk of further
infection. One of the dogs continued to show chronic signs of lethargy and fever and was treated with a second course of antibiotic after which it
recovered.
Cats and dogs, as well as birds and
farm mammals, are potential sources of animal-derived chlamydial infection in humans (Elliot et al.,
1985; Werth, 1989).
[MEW Comment: The
paucity of modern references, uncertainty concerning the chlamydial species
primarily responsible for canine infection and the fact that dogs are companion
animals to humans suggests the need for further research].
Bibliography
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