Protostrongylid parasites and pneumonia in captive and wild thinhorn sheep (Ovis dalli).

We describe health significance of protostrongylid parasites (Parelaphostrongylus odocoilei and Protostrongylus stilesi) and other respiratory pathogens in more than 50 naturally infected Dall's sheep (Ovis dalli dalli) from the Mackenzie Mountains, Northwest Territories (1998-2002) as well as in three Stone's sheep (O. d. stonei) experimentally infected with P. odocoilei (2000-2002). Histological lesions in the brain and distribution of P. odocoilei in the muscles of experimentally and naturally infected sheep were consistent with a previously hypothesized "central nervous system to muscle" pattern of migration for P. odocoilei. Dimensions of granulomas associated with eggs of P. odocoilei and density of protostrongylid eggs and larvae in the cranial lung correlated with intensity of larvae in feces, and all varied with season of collection. Prevalence of P. stilesi based on the presence of larvae in feces underestimated true prevalence (based on examination of lungs) in wild Dall's sheep collected in summer and fall. Similarly, counts of both types of protostrongylid larvae in feces were unreliable indicators of parasitic infection in wild Dall's sheep with concomitant bacterial pneumonia associated with Arcanobacterium pyogenes, Pasteurella sp., and Mannheimia sp. Diffuse, interstitial pneumonia due to P. odocoilei led to fatal pulmonary hemorrhage and edema after exertion in one experimentally infected Stone's sheep and one naturally infected Dall's sheep. Bacterial and verminous pneumonia associated with pathogens endemic in wild Dall's sheep in the Mackenzie Mountains caused sporadic mortalities. There was no evidence of respiratory viruses or bacterial strains associated with domestic ruminants, from which this population of wild sheep has been historically isolated.

Actinobacillus lignieresii infection in two horses.

A 10-year-old pregnant Norwegian Fjord horse was examined for gross swelling of the muzzle of 2 years' duration. Examination of biopsy specimens revealed diffuse dermal fibrosis, micropustule formation, and vascular thrombosis; large numbers of Actinobacillus lignieresii were isolated in pure culture. Prolonged treatment with i.v. administration of sodium iodide and oral administration of trimethoprim-sulfamethoxazole caused regression of the swelling and did not induce abortion. A 5-month-old American Paint filly was examined for swelling in the udder region. Bacteriologic culture of purulent material obtained from the left teat revealed A lignieresii. Treatment with oral administration of rifampin and trimethoprim-sulfamethoxazole resulted in complete resolution of clinical signs. To the authors' knowledge, these findings represent the first report of mastitis and chronic nasal cellulitis caused by A lignieresii infection in horses.

Lesions caused by natural infection with Streptococcus suis type 9 in weaned pigs.

In this paper we report on the spectrum and frequency of lesions observed in a prospective study of naturally occurring infections with Streptococcus suis type 9 (SS-9) in weaned pigs. SS-9 produced arthritis, meningitis, interstitial pneumonia, and endocarditis in 100%, 91%, 73%, and 42%, respectively, of pigs dying from the disease. The lesions were similar to those caused by S. suis type 2 (SS-2), however, SS-9 produced a different frequency of lesions. In SS-2 infections, bronchopneumonia is the most commonly observed lesion; meningitis, arthritis, and endocarditis are less frequently observed. Thus, SS-9 produced a different distribution of lesions from that reported for SS-2. Possible explanations for the differences found are discussed.

A case of bovine mastitis caused by Campylobacter jejuni.

A Campylobacter jejuni mastitis in a Holstein cow, 60 days into the first lactation, is reported. This was characterized by a sudden onset, a pyrexia, painful quarter and pink milk with a few small clots present. There was good response to a treatment protocol of: parenteral oxytetracycline, frequent stripping and intramammary infusions of erythromycin. This organism has a zoonotic property.

Protection of foals against experimental Rhodococcus equi pneumonia by oral immunization.

Two groups of three one to three week old foals were immunized orally on four occasions over five weeks with two strains of Rhodococcus equi, a clinical isolate from a pneumonic foal and a laboratory passaged Congo red negative variant of this strain. Three nonimmunized foals of similar age acted as controls. Three weeks after the last immunization, all foals were challenged on five occasions over seven days by aerosol infection with about 10(10) of the pneumonic foal isolate on each occasion. Control foals became seriously ill and were euthanized. Immunization with either strain protected foals equally against the challenge, and resulted in rapid lung clearance. Oral immunization can thus protect foals against severe challenge with R. equi. The proteins associated with Congo red colony staining appear not to be involved in protective immunity.

Polyacrylamide gel electrophoresis of whole-cell preparations of Rhodococcus equi.

The whole-cell proteins of ten strains of Rhodococcus equi isolated from horses, pigs, or humans, including the type strain ATCC 6939, were examined by sodium dodecyl sulphate-polyacrylamide gel electrophoresis. The protein profiles of seven different capsular serotypes and the type strain were very similar when bacteria were cultured under the same conditions. Protein profiles were largely unaffected by incubation at two temperatures (30 degrees C, 37 degrees C) or times (12 h, 48 h). There were generally minor differences in protein profiles between strains grown in different media (brain heart infusion, nutrient, minca broths, tryptic soy-blood agar) with the marked exception of a prominent diffuse 17.5 kd protein which was expressed in nutrient broth. This protein was not produced by the type strain and was lost on repeated passage in vitro (50th, 100th passage) in two of three other strains examined.

Antibody response of horses to Rhodococcus equi antigens.

The antigens extracted from strains belonging to seven capsular serotypes of Rhodococcus equi, as well as from two wild strains isolated from pneumonic foals, were examined. Whole-cell antigens and soluble products present in broth culture supernatants were separated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, electroblotted onto nitrocellulose, and stained with serum from hyperimmunized rabbits or foals. Foal sera used included sera from pneumonic animals with known titer to equi factors; from animals bled monthly on a farm with enzootic pneumonia, and from animals bled monthly on a farm with no history of R. equi pneumonia. The humoral response of foals to somatic antigen preparations was negligible, with few differences noted between sera from healthy, subclinically affected, and sick foals. The humoral response to R. equi broth culture supernatant products appeared more marked and was related to equi factor antibody titer. These findings suggest that the humoral response to R. equi whole-cell antigens is unimportant in protection against disease, which is consistent with the behavior of the organism as a facultative intracellular pathogen.

The identification and antimicrobial susceptibility of anaerobic bacteria from pneumonic cattle lungs.

One hundred and forty-four lungs obtained postmortem from cattle with pneumonia were cultured for anaerobic bacteria. Forty-five lungs yielded 73 anaerobic isolates belonging to 20 species. The number of isolations of anaerobes from acute fibrinous or suppurative bronchopneumonias (32.5%) was slightly lower than from similar chronic bronchopneumonias (36.5%). Anaerobes were not recovered from 15 lungs showing macroscopic changes not of bacterial origin, nor from 13 healthy lungs. The predominant genera isolated were Bacteroides, Peptococcus, Fusobacterium and Clostridium. The most common species were P. indolicus (15 isolates), B. asaccharolyticus (nine), F. necrophorum (six), C. perfringens (four) and B. fragilis (four). There was a significant correlation between the presence of Corynebacterium pyogenes (p less than 0.001) or Escherichia coli (p less than 0.01) and the presence of anaerobes in the lungs. The isolated anaerobic bacteria were generally susceptible to ampicillin, penicillin G, cefoxitin, cephalothin, clindamycin, chloramphenicol, erythromycin, tetracycline and metronidazole. The B. fragilis and C. perfringens isolates showed multiple antibiotic resistance, and five P. indolicus isolates were resistant to tetracycline.