Clinical and Microbiological Study of an Otitis Media Outbreak in Calves in a Dairy Herd

On a dairy farm, otitis media was diagnosed in 64 suckler calves (21.8 %) during a study period of 2 years, and in 10 calves (3.4 %) in the third year. The inflammation was unilateral in 63 and bilateral in 11 calves. The affected calves were dull, lacked appetite, were pyrexic and displayed drooping ear or ears and tilted heads with purulent discharge exuding from the external ear canal. Of the affected animals, 56 (87.5 %) were aged between 3 and 8 weeks. Morbidity was higher during the calving season and during the autumn and winter months (October–December). Pasteurella haemolytica was isolated from 21 (32.8 %), P. multocida from 20 (31.2 %), Actinomyces pyogenes from 11 (17.2 %) and Streptococcus pneumoniae from three (4.7 %) of the clinically affected calves only during the first two study years. The exudate of the acute ear infections contained, in addition to Pasteurella spp., various bacteria and yeasts. Most of these bacteria were isolated from healthy ears as well, and are likely to be part of the normal ear flora. On the other hand, most of the yeasts were isolated from otitic calves. After a short course of an appropriate treatment, infections healed in all cases. Possible preventive measures are discussed.     

Clinical efficacy of florfenicol in the treatment of calf respiratory tract infections

This paper reports on a study of the aetiology of calf pneumonia and the clinical efficacy of florfenicol, a new antibiotic in Turkey. Twenty-seven weaned and unweaned calves (13 males and 14 females) between 1 and 16 months of age brought to the clinics of Sel?uk University, Faculty of Veterinary Science. Broncho-alveolar lavage (BAL) fluid samples were taken from the animals diagnosed to have upper respiratory tract infection associated with bronchitis (N=2), bronchitis (N=5), bronchopneumonia (N=4), pneumonia (N=3), pleuropneumonia (N=11), bronchopneumonia plus pulmonary oedema (N=2) based on the results of the clinical and laboratory examinations. Then microbiological isolation and antibiotic culturing were performed. The animals were treated with 1 ml/15 kg (20 mg/kg) florfenicol (Nuflor, DIF) twice within 48 hours via intramuscular injection. At the end of the treatment, 23 of the weaned and unweaned calves were completely healed, 1 calf had died and 3 calves showed no healing. The results of BAL samples and microbiological examinations of the 3 calves that did not respond to the treatment indicated that these cases were affected by mixed infections of yeasts, fungi, and bacteria. Widespread pleuropneumonia was observed. According to the results of the microbiological examination of the BAL samples, Mannheimia (Pasteurella) haemolytica had the highest isolation rate (25%) compared with the other isolated bacteria, namely, Klebsiella pneumonia (20%), Actinomyces pyogenes (15%), beta-hemolytic streptococci. (10%), Staphylococcus spp. (5%), and E. coli (5%). The study also revealed fungi [Penicillum spp. (5%) and Aspergillus spp. (5%)] and two calves (10%) had a yeast infection.. We conclude that florfenicol has a high bacteriological and clinical efficacy (100% and 96% respectively) in the treatment of calf respiratory tract diseases.     

Treatment of feline otitis externa due to Otodectes cynotis and complicated by secondary bacterial and fungal infections with Oridermyl auricular ointment

A blinded randomized study was conducted on 24 cats to confirm the presence of bacterial and/or fungal secondary infections associated with otoacariasis and to verify the efficacy of Oridermyl, an acaricidal/antibiotic/antifungal/anti-inflammatory ointment, for treatment of the primary infestation and secondary infections. Sixteen cats were treated once daily for 10 d; 4 cats were not treated and 4 were treated with a placebo ointment. On Days 0 and 10, ears were swabbed for counts of bacteria and yeasts, for bacterial culture and sensitivity, and examined for determination of the degree of clinical otitis. Auricular secretions were removed for mite counts on Day 10, except for 8 treated cats that were done on Day 30. There was a high number of bacteria and yeasts in most cats and Oridermyl treatment significantly decreased those numbers. Staphylococci were the most frequently isolated bacteria. No live ear mites were found in cats treated with Oridermyl or the placebo ointment.     

The aerobic bacterial flora of the middle and external ears in normal dogs

The aerobic bacterial flora of the middle and external ears was elucidated in 30 normal dogs (60 ears). Bacterial swab samples were obtained by rubbing the surface of the tympanic cavity and external ear canal. In the middle ear, bacteria were cultured from 48 per cent of the total ears and mainly included Escherichia coli (8 per cent), yeasts (8 per cent), staphylococci (7 per cent) and branhamella (7 per cent). In the external ear, bacteria were found in 46 per cent of the total ears and staphylococci (19 per cent) and yeasts (7 per cent) were the main isolates. Mycoplasma was found in one external ear sample, but in no middle ear samples in an examination of 20 ears. The same type of bacterium was hardly ever found in both the middle and external parts of each ear.     

Isolation of Mycoplasmas from nasal swabs of calves affected with respiratory diseases and antimicrobial susceptibility of their isolates

Nasal swabs of 293 calves were examined for Mycoplasma. The samples were collected from calves affected with respiratory diseases on 71 farms in various parts of Japan between 1996 and 1997. Mycoplasma bovirhinis was isolated from 47 of 293 calves (16.0%). Mycoplasma alkalescens, M. bovis, M. arginini, M. bovigenitalium and Acholeplasma spp. were isolated from 19 (6.5%), seven (2.4%), four (1.4%), four (1.4%) and 18 (6.1%) calves, respectively. Pasteurella multocida and P. haemolytica were isolated from 60% of Mycoplasma-positive calves. However, other bacteria were not isolated from calves. To evaluate the antimicrobial susceptibility of their isolates, 68 M. bovirhinis, 21 M. alkalescens and 10 M. bovis strains were examined for 12 antimicrobial agents. All isolates showed higher susceptibility to tiamulin than to the other drugs used in the study. However, erythromycin had no effect on any of the Mycoplasma strains studied. The field isolates were less susceptible than the type strains to some drugs, such as spiramycin, oxytetracycline and tylosin.     

Mycoplasma otitis in California calves.

A retrospective study of Mycoplasma otitis in California calves submitted for necropsy between 1993 and 2002 was conducted to characterize the demographic features of the disease and the pathologic findings associated with infection. Sixty-one confirmed cases of Mycoplasma otitis were identified among 20,525 necropsied cattle. All affected animals were calves, ranging in age from 2 weeks to 4 months and with a median age of 1.5 months. Ninety-two percent of the cases were dairy breeds. A higher percent of necropsied calves with Mycoplasma otitis were males (0.45%) than females (0.23%). The proportion of cases that had Mycoplasma otitis increased from 1993 to 2002, and there was a significant (P < 0.05) seasonal distribution, with the highest proportion in the spring and the lowest in the summer months. Infections involved both the middle and inner ear and were characterized by a suppurative inflammatory response with extensive bony involvement. Three species of Mycoplasma were isolated from the ears: M. bovis, M. bovirhinis, and M. alkalescens. Concurrent pneumonia occurred in 47 cases (77%), and Mycoplasma was isolated from the lungs of 30 of those cases. The increasing proportion of Mycoplasma otitis cases in the past 10 years emphasizes the importance of identifying risk factors that could be modified to lower the incidence of this disease in calves.     

Bovine herpesvirus-1 and Pasteurella haemolytica aerobiology in experimentally infected calves

Eight calves (2 calves in each of 4 groups) were exposed to an aerosol of bovine herpesvirus-1 (BHV-1) and 4 days later to an aerosol of Pasteurella haemolytica. Samples of tracheal and exhaled air were taken simultaneously beginning 1 day before viral exposure and once a day up to 3 to 4 days after the bacterial exposure. Samples were also taken during the period of aerosol exposure. Only 0.04% to 0.42% of P haemolytica-carrying droplets of the bacterial aerosol passed beyond the cranial part of the respiratory tract to the trachea. Nevertheless, numbers of bacteria as few as 1 bacterium/L of tracheal air were sufficient to produce fatal disease in the lungs of BHV-1-infected calves. In 1 of 4 groups, BHV-1 was isolated from most daily samples of exhaled and tracheal air. Pasteurella haemolytica was isolated 7 times more frequently from air when calves were kept at 1 C than when calves were kept at 23 C. The number of P haemolytica-carrying droplets in exhaled air was low (less than 1/L of air); however, samples obtained during the time that calves were coughing contained up to 10 P haemolytica-carrying droplets/L of air. It was learned that the cranial part of the respiratory tract serves as an efficient filter on inhalation and exhalation, but this filter is deficient in the animal when coughing occurs. This process expels infective droplets of size suitable for inhalation by other cattle in close proximity.     

P-76 The effect of omega-3 fatty acid supplementation on cutaneous and plasma fatty acid concentrations in dogs with atopic dermatitis

The objectives of this study were to evaluate in vivo tolerance, and antimicrobial and clinical activities of a topical otic preparation containing EDTA tromethamine (Tris) and chlorhexidine digluconate 0.15% solution (Otodine^®) in dogs with chronic bacterial otitis externa. Eleven dogs were included. The affected ears were filled with the solution once daily during a 2-week period. Dogs were evaluated on days 0, 14 and 28. Three clinical parameters (exudate, erythema, pain) and three cytologic parameters ( Malassezia , cocci, rods) were scored (0–4 scale) by otoscopic and cytological examinations of otic exudate. Bacterial cultures were performed at each time point. If there were bacteria on cytological examination on day 14, the dogs were treated with the original product, with the addition of enrofloxacin (5%) applied 10 min after the original product, for a further 2 weeks. All 11 cases yielded isolates of resistant gram-negative bacteria; gram-positive bacteria were also isolated from six of 11 dogs. On day 14, six of 11 dogs were negative on culture examination; on day 28, 10 of 11 were negative and only one case had a positive culture. On day 14, clinical and microbial scores (cytology) were reduced by 54.6 and 71.1%, respectively, and by 85.7 and 94% on day 28. All cases reported good tolerance of the treatment. The results show that this ear solution was helpful in the management of chronic bacterial otitis externa in dogs and was well tolerated. There seems to be a synergistic effect of the combination of Tris-EDTA/chlorhexidine digluconate 0.15% solution, and an antimicrobial agent (enrofloxacin) against resistant gram-positive and gram-negative bacteria.
Funding: Self-funded.     

Evaluation of an ear cleanser for the treatment of infectious otitis externa in dogs

Thirty-one ears (16 dogs) with otitis externa originating from bacterial or yeast infections were enrolled in a study to evaluate the in vivo efficacy of an ear cleanser containing 2.5% lactic acid and 0.1% salicylic acid for the treatment of infectious otitis externa. The affected ears were treated with the ear cleanser twice daily for 2 weeks and evaluated after 1 and 2 weeks of treatment. The ear cleanser was effective in resolution of infection in 67.7% of the ears, and clinical signs of infectious otitis externa were significantly reduced within 2 weeks.     

P‐74 Evaluation of the in vivo effects of Tris‐EDTA and chlorhexidine digluconate 0.15% solution in chronic bacterial otitis externa: 11 cases

The objectives of this study were to evaluate in vivo tolerance, and antimicrobial and clinical activities of a topical otic preparation containing EDTA tromethamine (Tris) and chlorhexidine digluconate 0.15% solution (Otodine^®) in dogs with chronic bacterial otitis externa. Eleven dogs were included. The affected ears were filled with the solution once daily during a 2‐week period. Dogs were evaluated on days 0, 14 and 28. Three clinical parameters (exudate, erythema, pain) and three cytologic parameters (Malassezia, cocci, rods) were scored (0–4 scale) by otoscopic and cytological examinations of otic exudate. Bacterial cultures were performed at each time point. If there were bacteria on cytological examination on day 14, the dogs were treated with the original product, with the addition of enrofloxacin (5%) applied 10 min after the original product, for a further 2 weeks. All 11 cases yielded isolates of resistant gram‐negative bacteria; gram‐positive bacteria were also isolated from six of 11 dogs. On day 14, six of 11 dogs were negative on culture examination; on day 28, 10 of 11 were negative and only one case had a positive culture. On day 14, clinical and microbial scores (cytology) were reduced by 54.6 and 71.1%, respectively, and by 85.7 and 94% on day 28. All cases reported good tolerance of the treatment. The results show that this ear solution was helpful in the management of chronic bacterial otitis externa in dogs and was well tolerated. There seems to be a synergistic effect of the combination of Tris‐EDTA/chlorhexidine digluconate 0.15% solution, and an antimicrobial agent (enrofloxacin) against resistant gram‐positive and gram‐negative bacteria. Funding: Self‐funded.     

Etiology of respiratory disease in non-vaccinated, non-medicated calves in rearing herds

The aim of this study was to examine the occurrence of bacterial, mycoplasmal and viral pathogens in the lower respiratory tract of calves in all-in all-out calf-rearing units. According to clinical status, non-medicated calves with and without respiratory disease signs were selected of the 40 herds investigated to analyse the micro-organisms present in healthy and diseased calves. Tracheobronchial lavage (TBL) and paired serum samples were analysed for bacteria, mycoplasmas, respiratory syncytial virus (RSV), parainfluenza virus 3 (PIV3), bovine corona virus (BCV) and bovine adenovirus (BAV). Pasteurella multocida was the most common bacterial pathogen. It was isolated from 34% of the TBL samples in 28 herds and was associated with clinical respiratory disease (p < 0.05) when other pathogenic bacteria or mycoplasma were present in the sample. Mannheimia spp. and Histophilus somni were rarely found. Mycoplasma bovis was not detected at all. Ureaplasma diversum was associated with clinical respiratory disease (p < 0.05). TBL samples from healthy or suspect calves were more often negative in bacterial culture than samples from diseased calves (p < 0.05). No viral infections were detected in six herds, while 16-21 herds had RSV, BCV, BAV or PIV3. In the herds that had calves seroconverted to BCV, respiratory shedding of BCV was more frequently observed than faecal shedding. This study showed that the microbial combinations behind BRD were diverse between herds. M. bovis, an emerging pathogen in many countries, was not detected.     

Response of the respiratory tract of calves kept at controlled climatic conditions to bovine Herpesvirus 1 in aerosol.

Seven experiments with four calves each were conducted in which the calves spent at least four days of adaptation in an environmental chamber and then were subjected to climatic stress in the form of a number of constant ambient temperature and humidity combinations. On the second day of climatic stress the calves were individually exposed to measured numbers of infectious units of bovine herpesvirus 1 (BHV1, virus of infectious bovine rhinotrachetis) in aerosol. The calves were killed seven or eight days later. Mycoplasma were found in some nasal swabs and in one lung. Certain bacteria but no Pasteurella were often isolated from the lungs. Bovine herpesvirus 1 was isolated from chamber air and from most postinoculation nasal swabs, tracheas and lungs. The number of macro- and microscopic lesions did not appear to be influenced by the climatic conditions of the experiments. The histopathological changes in epithelium at all levels of the respiratory tract were described in detail.     

Bacterial Identity and Characteristics in Healthy and Unhealthy Respiratory Tracts of Sheep and Calves

Barbour, E.K., Nabbut, N.H., Hamadeh, S.K. and Al-Nakhli, H.M., 1997. Bacterial identity and characteristics in healthy and unhealthy respiratory tracts of sheep and calves. Veterinary Research Communications, 21 (6), 421-430The aim of this study was to compare different bacteriological aspects of the respiratory systems of healthy (H) versus unhealthy (UH) animals with respiratory signs. The prevalence of different bacterial species was determined in the upper and lower respiratory tract of H and UH Najdi sheep, Somali sheep and Holstein calves. The characteristics of Pasteurella spp. isolates, and the biotype of Pasteurella haemolytica were identified in H and UH animals. Eighteen out of 28 (64.3%) of the identified bacterial species in the upper respiratory tract were more prevalent in the nasal cavities of UH Najdi and Somali sheep and Holstein calves with respiratory signs than in apparently healthy animals; four of the most prevalent bacteria in the upper respiratory system of UH sheep were Moraxella spp., Pseudomonas pseudomallei, Erysipelothrix spp., and Pasteurella multocida, while three of the most prevalent bacteria in UH calves were Pasturella haemolytica, Actinomyces spp., and Pseudomonas aeruginosa. The prevalence of six different bacterial species was greater in the lungs of UH animals, namely Actinomyces pyogenes, Erysipelothrix spp., P. haemolytica, Pasteurella ureae, Staphylococcus aureus, and Staphylococcus epidermidis, which could be risk factors in the complexity of the prevalent respiratory diseases of the animals surveyed.Of the biochemical, cytological and colonial characteristics studied in the identified P. haemolytica and P. multocida, two characters were significantly different (p < 0.05) in organisms isolated from UH as compared to those from H animals. These were the higher loss of haemolytic power by the strains of P. haemolytica and the decreased fermentation of trehalose by all the strains of P. multocida recovered from healthy animals.The only biotype of P. haemolytica isolated from H animals was biotype A, while both biotypes A (88.0% of the isolates) and T (12.0% of the isolates) were recovered from UH animals.     

Immunoperoxidase evaluation of pneumonic lesions in calves naturally infected with Pasteurella haemolytica

Immunoperoxidase technique was applied for pathological study on naturally occurring pneumonic tissues of calves from which Pasteurella haemolytica was isolated. Multifocal necrosis occurred in the lungs of 25 out of 42 calves (59.5%) and P. haemolytica antigen was detected in 22 out of the 25 calves (88.0%). The calves were divided into 3 groups according to the number of P. haemolytica isolated. The positive rate of the bacterial antigen detected by the technique was 66.6% (28/42) on the average, reaching up to 85.7% (18/21) in the group from which the largest number of P. haemolytica was isolated.     

Evidence that blood-borne infection is involved in the pathogenesis of bovine pneumonic pasteurellosis

Five calves were inoculated intravenously with 10(8) colony forming units (cfu) of Pasteurella haemolytica A1; the mean score for pneumonic consolidation 3 days post-inoculation was 28%, and the mean clinical score was 7.8. Five calves inoculated intratracheally with 10(9) cfu of the same strain of P. haemolytica had comparable scores (34% and 8.8). Histological lesions of fibrinous pneumonia were similar in all calves. P. haemolytica was recovered from all but one of the affected lungs. From one calf killed in extremis 3 hours after intravenous inoculation, numbers of bacteria recovered from lung were 1,000-fold greater than from liver and spleen. A similar difference in bacterial numbers was also obtained from a gnotobiotic calf killed in extremis, 12 hours after intravenous inoculation of 10(8) cfu P. haemolytica. Evidence from these experiments supports the hypothesis that the blood-borne route is important in the pathogenesis of bovine pneumonic pasteurellosis.     

Pneumonia in calves: characterization of the bacterial spectrum and the resistance patterns to antimicrobial drugs

The population under study included young calves with pneumonia (group A, n = 13) and their controls (group B, n = 9), as well as older calves from which the lungs with (group C, n = 90) or without (group D, n = 10) lesions were collected after slaughter. Arcanobacterium pyogenes was the organism most commonly isolated from calves in group A (46%), followed by Haemophilus somnus (23%), Mannheimia haemolytica (15%), Streptococcus suis and Pasteurella multocida (7.7% each). Only S. suis (22%) and P. multocida (11%) were found in group B. P. multocida was isolated from 32% group C calves, H. somnus from 11%, A. pyogenes from 7.8%, M. haemolytica from 2.2% and S. suis from 1.1%. No specific pathogens were isolated in group D. Prevalence of Mycoplasma bovis infection was 69% in group A and 37% in group C. Ninety-eight strains were tested for resistAnce to antibiotics. Resistance to penicillin and ampicillin was present only in M. haemolytica (46%). High percentages of resistant strains were observed for streptomycin (48-100%), tetracycline (15-43%), sulfonamides alone (14-100%) or in combination with trimethoprim (0-100%). Therapeutic approaches to bacterial calf pneumonia in the area under study should be modified according to the isolated bacterial population, the observed antimicrobial resistances and the growing importance of Mycoplasma bovis.     

Experimental infection of calves with Pasteurella multocida Serovar A: 3 isolated in Japan

Pasteurella multocida, serovar A: 3, selected by pathogenicity in mice from among 10 strains isolated from pneumonic lesions of calves, was adjusted to 10(7), 10(8) and 10(10) colony-forming units (CFU), and inoculated intratracheally into four calves. All calves showed pyrexia and had lungs with congestion and hepatization. Inoculation with 10(10) CFU of bacteria produced respiratory symptoms and abscesses in lungs. This information will aid elucidation of the pathogenicity of P. multocida and the development of vaccines.     

Meningitis in neonatal calves: 32 cases (1983-1990).

Case records of 32 neonatal calves with the antemortem diagnosis of meningitis were reviewed. Mean age at admission was 6 days (range, 11 hours to 30 days), and the most common concurrent clinical problem was diarrhea (16/32). Twenty-seven of the calves were available for necropsy. At postmortem, there was evidence of septicemia in 22 (81%) of these calves. Escherichia coli was the organism most frequently isolated (11/16; 69%) from the CNS. The major clinical signs of CNS disturbance observed over the course of hospitalization were lethargy, recumbency, anorexia, loss of suckle reflex, and coma. Leukocytosis and a left shift was evident in 11 of 15 (73%) calves. Concurrent metabolic problems that could have aggravated the CNS disturbance included hyperkalemia and respiratory acidosis. Analysis cerebrospinal of fluid from 22 of the calves, revealed pleocytosis, xanthochromia, turbidity, and high total protein concentration. Cytologically, neutrophils predominated in the CSF in calves with acute disease. Mononuclear cells dominated in calves with chronic disease. Microscopically, bacteria were evident in 10 of 22 (45%) of the antemortem CSF samples and bacteria were isolated from slightly more than half (11/19) of the specimens subjected to microbial culturing. Escherichia coli was the agent most frequently isolated from the CSF. Two of the 9 E coli isolates were resistant to trimethoprim potentiated sulfonamide drugs and all (4/4) of the CSF E coli isolates tested for susceptibility to triple-sulfonamide drugs were resistant. Twenty-seven of the 32 calves died or were euthanatized within 2.43 days after hospitalization.(ABSTRACT TRUNCATED AT 250 WORDS)     

The pulmonary clearance of Pasteurella hemolytica in calves infected with bovine parainfluenza-3 virus.

The purpose of this study was to determine if parainfluenza-3 virus in calves interfered with normal pulmonary bacterial clearance. Three groups (A, B and C) of four calves each were exposed to an aerosol of parainfluenza-3 virus. Three days later the four hour pulmonary clearance of Pasteurella hemolytica was determined on the first group (A), seven days later on the second (B) and 11 days later on the third (C). Group A had a mean pulmonary bacterial retention of 3.6 +/- 3.5%. Group B was 83.1 +/- 35.9% and Group C was 41.2 +/- 30.9%. The results demonstrate that parainfluenza-3 virus interfered with the pulmonary bacterial clearance of Pasteurella hemolytica particularly on day 7 and also on day 11 but not on day 3. This inhibition of pulmonary clearance caused by the virus may be a key factor in the pathogenesis of pneumonic pasteurellosis. Histological examination of the lungs did not demonstrate a correlation between pulmonary retention of bacteria and the development of pathological changes.     

Genetic analysis of virulence factors of Mannheimia (Pasteurella) haemolytica A1

Sixteen 3-week-old calves were intratracheally inoculated with Mycoplasma bovis. Follow-up consisted of regular bronchoalveolar lavages (BALs) and clinical examinations. Animals were slaughtered from 4 to 21 days after inoculation. Counts were made of the mycoplasmas and other bacteria systematically isolated from the BAL liquids and lung lobes after slaughter. On the 6th day, spectinomycin 20mg/kg was given intramuscularly in three repeated doses at 24h intervals to six randomly chosen calves. All animals had developed a persistent M. bovis infection with a maximum BAL count on the 6th day (start of treatment). Co-occuring Pasteurella multocida infection was found in most animals with a maximum rate on the 14th day. The extent of lung surface lesions varied widely (0-64%) but was greater in the later slaughtered calves. Average counts of M. bovis and P. multocida in the BAL liquids were lower in treated calves than in untreated ones but the difference was not statistically significant. However, M. bovis and P. multocida counts in the lungs of the treated group were significantly lower than in the untreated group (p=0.003 and 0.009, respectively).