Community-acquired infectious pneumonia in puppies: 65 cases (1993-2002)

OBJECTIVE

To identify causative organisms, treatment, outcome, and prognosis for dogs < 1 year old with community-acquired infectious pneumonia.

DESIGN

Retrospective case series.

ANIMALS

65 dogs.

PROCEDURES

Dogs were considered to have community-acquired infectious pneumonia if they had clinical signs of primary respiratory tract disease in conjunction with radiographic evidence of alveolar disease and positive results following bacterial culture of tracheal wash fluid.

RESULTS

Most dogs were hypoxemic at the time of initial examination, with pulmonary function becoming worse during the first few days of hospitalization before improving; 57 (88%) dogs survived to discharge. Bordetella bronchiseptica was isolated from tracheal wash fluid from 32 (49%) dogs, and other organisms, predominantly gram-negative enteric bacteria, were isolated from the other 33 (51%). Dogs with Bordetella pneumonia were significantly younger (median, 14 vs 21 weeks), were significantly more likely to have been obtained from a pet store (19/31 vs 7/32), had been owned for a significantly shorter time prior to the onset of illness (median, 18 vs 90 days), had significantly higher PvCO2 values at initial examination (median, 48.7 vs 41.3 mm Hg), were significantly more likely to receive supplemental oxygen (25/32 vs 16/33), and had significantly longer hospitalization times (mean, 7.2 vs 4.9 days) than did dogs with pneumonia caused by any other organism.

CONCLUSIONS AND CLINICAL RELEVANCE

Results suggested that a type of community-acquired infectious pneumonia could be identified in dogs < 1 year old, with disease being more severe in dogs with Bordetella pneumonia than in dogs with pneumonia caused by other bacterial organisms.

CD11b is required for the resolution of inflammation induced by Bordetella bronchiseptica respiratory infection

CD11b is a cell surface receptor that contributes to many cellular processes which are involved in the generation of a protective immune response against pathogenic organisms. In this work, the natural host-pathogen model of murine Bordetella bronchiseptica infection was used to explore the role of CD11b in respiratory immunity. Following intranasal inoculation, CD11b-/- mice rapidly succumb to B. bronchiseptica respiratory infection, highlighting the prominent role of CD11b in the generation of a protective immune response in this model. CD11b appears to be required for both the control of bacterial numbers and the regulation of cellular responses in the lungs. An increased accumulation of neutrophils in the lungs of CD11b-/- mice as compared with wild-type mice suggests that CD11b contributes to the regulation of cellular responses to respiratory infection. This accumulation may be explained by a decrease in apoptosis that is observed in the absence of CD11b following cellular interactions with B. bronchiseptica. Interestingly, this role for CD11b in the regulation of cellular accumulation appears to be critically important for the resolution of damage associated with the type III secretion system (TTSS) of B. bronchiseptica. These data provide new insight into the key role CD11b plays in the resolution of damage in the lower respiratory tract, as well as the B. bronchiseptica virulence determinant that induces it.

Canine distemper and related diseases: report of a severe outbreak in a kennel

An outbreak of canine distemper in a kennel of German shepherds in the province of Bari is reported. Six 42-day-old pups developed typical signs of canine distemper (fever, conjunctivitis, respiratory distress and enteritis) and died within 7-10 days. Neurological symptoms were observed only in one pup. Four additional pups, which had shown no sign of illness, were separated and vaccinated, but two of these developed a severe, fatal nervous form 15 days later. Post-mortem examination, carried out on two pups which died without neurological signs, showed pneumonia and enteritis, more severe in one of the two examined pups. Smears from the brain and the conjunctiva of both dogs tested positive for canine distemper virus (CDV) by an immunofluorescent assay, confirmed by the identification of viral RNA using RT-PCR. Bordetella bronchiseptica and a canine adenovirus strain, characterized as canine adenovirus type 2 by a differential PCR assay, were isolated from the lungs of the pup showing the most pronounced lesions. Furthermore, canine coronavirus was detected by PCR in the intestinal content of this pup, suggesting a multifactorial aetiology of the outbreak.

Protection against experimental Bordetella bronchiseptica infection in mice by active immunization with killed vaccine

Mice immunized with a killed vaccine of phase I Bordetella bronchiseptica were challenged with various numbers of virulent B. bronchiseptica by intraperitoneal, intracerebral, or intranasal routes. The course of infection was compared among these routes, and the protective effect of vaccination was quantitatively analyzed. In ddN mice infected intraperitoneally with 1.8 X 10(8) cells (ca. 80 times the 50% lethal dose [LD50]) the organisms rapidly increased in the intraperitoneal fluid, spleen, and liver within few days and caused splenic atrophy, septicemia, and death. However, immunizations with 5 X 10(9) cells gave the mice a high agglutinin titer and suppressed the increase in the number of organisms. With four immunizations, the lungs and livers were clear within 3 days, and with one or two immunizations, they were clear within 7 days. These immunizations effectively protected the mice from death but did not protect them from splenic atrophy. In the intracerebral infection with 1.4 X 10(6) cells (ca. 1.2 X 10(5) LD50), the number of organisms rapidly increased in the brain and caused encephalitis, splenic atrophy, and death. However, four or five immunizations completely suppressed the increase in the brain and protected the mice from death and splenic atrophy. After intranasal infection with 4 X 10(6) cells (ca. 25 LD50), the organisms rapidly increased in the nasal cavity and lungs and caused pneumonia and death. Immunization with 5 X 10(9) cells was effective in clearing the organisms from the lungs and in protecting against death and splenic atrophy. However, the organisms were not cleared from the nasal cavity for 60 to 150 days after the challenge with as little as 10(2) cells, even in the mice with an agglutinin titer as high as 1:10,000.

Bordetella pertussis respiratory tract infection in the mouse: pathophysiological responses

The influence of living Bordetella pertussis on the induction and duration of pathophysiological reactions in mice infected intranasally with graded doses of culture was studied. Lethally infected mice showed loss of body weight, spleen atrophy, pronounced hypothermia and hypoglycemia, and highly elevated levels of leukocytes and serum immunoreactive insulin. Sublethally infected mice showed normal weight gain, practically normal temperature, spleen enlargement, lesser pronounced hypoglycemia, lower but significantly elevated levels of leukocytes and serum immunoreactive insulin, and histamine sensitization. Intensity of each reaction was related to the degree of lung infectivity. Hypothermia and leukocytosis were highly correlated. Concentration of serum immunoreactive insulin was closely related to the level of leukocytosis but not to the level of glucose. The strain and age of mice significantly affected the degree and duration of the reactions. The results suggest that the intranasally infected mouse may provide a useful model for investigations on whooping cough.

Bordetella parapertussis. Recent experience and a review of the literature

During 1974, eight of 37 (22%) Bordetella organisms isolated from patients in Cincinnate were Bordetella parapertussis. This is in contrast to other experience in the United States where parapertussis has comprised less than5% of the Bordetella species isolated and suggest that B parapertussis infection may be more common in this country than generally recognized. The failure to appreciate the presence of this infection may result from the lack of cultures taken from children with mild disease and the failure todistinguish B parapertussis from B pertussis. Ccultures were obtained from family members of three of the children with B parapertussis, and B pertussis was isolated from members of two families, including the mother and sister of a child who died of pneumonia and encephalopathy. These cases suggest that patients with severe disease associated with B parapertussis should be carefully evaluated for the possibility of dual infection caused by b pertussis.