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 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.     

Clavulanate-potentiated amoxycillin: activity in vitro and bioavailability in the dog

Clavulanic acid is an inhibitor of beta-lactamase (penicillinase) and when used with amoxycillin the resulting combination becomes active against most bacteria resistant to amoxycillin through production of beta-lactamase. A total of 551 bacterial isolates from dogs and cats were examined by disc sensitivity testing, which showed that there was amoxycillin resistance particularly among staphylococci (50 per cent), Klebsiella species (97 per cent) and Escherichia coli (28 per cent). A combination of potassium clavulanate and amoxycillin reduced the incidence of resistance to 0.3, 3 and 7 per cent, respectively. Minimum inhibitory concentrations were determined for a number of the isolates and showed marked reductions in the presence of potassium clavulanate. A formulation containing amoxycillin trihydrate and potassium clavulanate (4:1) was dosed to beagles at 12.5 mg/kg. Concentrations of the drugs in blood, tissue fluid and skin showed that both drugs were sufficiently well absorbed and distributed to allow a prediction of efficacy against infections caused by beta-lactamase producing bacteria.     

Inflammatory middle ear disease of the dog: the clinical and pathological features of cholesteatoma, a complication of otitis media

During a study of inflammatory middle ear disease in the dog cholesteatoma was found to accompany otitis media in seven of the 62 ears examined (11 per cent). The clinical, radiological and pathological findings in these animals imply that cholesteatoma in the dog is an aggressive lesion which must be differentiated from uncomplicated otitis media.     

Prevalence, causes and laboratory diagnosis of subclinical mastitis in the goat

Five goat herds were examined to determine the prevalence and causes of subclinical mastitis and to assess the value of some laboratory tests currently used on milk samples as aids in the diagnosis of caprine mastitis. In the 170 samples taken from the pairs of mammary glands of 85 goats, the prevalence of infection in the different herds ranged from 15 per cent to 79 per cent of halves. Just over one-third (36 per cent) of all halves were infected, the organisms isolated being coagulase-negative staphylococci (80 per cent), coagulase-positive staphylococci (16 per cent), alpha-haemolytic streptococci (2 per cent) and Pasteurella haemolytica (2 per cent). Neither anaerobic organisms nor mycoplasmas were found. Tests confirmed that the coagulase-positive staphylococci were pathogens but that the coagulase-negative staphylococci rarely caused detectable disease in the caprine udder. The large between-herd variation in the geometric mean cell counts of uninfected milk samples means that somatic cell counts, the Whiteside test and the California mastitis test, are unreliable as aids in the diagnosis of caprine mastitis.     

The role of Pityrosporum pachydermatis in otitis externa of dogs: evaluation of a treatment with miconazole.

The bacterial and mycotic flora were assessed in 158 ears of dogs with otitis externa and in 101 ears of healthy control dogs. Pityrosporum pachydermatis occurred in 57 per cent of ears with otitis externa and in 17 per cent of clinically healthy ears. Staphylococci and Pseudomonas aeruginosa were the predominant bacteria in otitic ears, micrococci and Bacillus spp were the most frequent isolates from clinically healthy ears. P pachydermatis, Ps aeruginosa and Candida tropicalis occurred in monoculture in a significant number of mainly chronic cases of otitis externa. A combination preparation, containing miconazole, polymyzin B and prednisolone, was highly effective in controlling the clinical signs of otitis externa and eliminating flora from the affected ears. The data presented suggest that yeasts, and especially P pachydermatis, may be significant pathogens in otitis externa and that antimycotic treatment is an essential part of the treatment of otitis externa in dogs.     

Survey of the incidence and aetiology of mastitis on dairy farms in England and Wales

A survey of clinical and subclinical mastitis was carried out on 97 dairy farms in England and Wales, selected at random from members of a national milk recording scheme. The farmers were asked to collect aseptic milk samples from five consecutive cases of clinical mastitis and from five quarters with high somatic cell counts using a defined protocol, and they completed a questionnaire that included information on the cows sampled, the herd and the history of mastitis in the herd. The samples were collected throughout the year. The mean incidence of clinical mastitis was 47 cases per 100 cows per year (estimated from historic farm records) and 71 cases per 100 cows per year (estimated from the samples collected). Streptococcus uberis and Escherichia coli were isolated in pure culture from 23.5 per cent and 19.8 per cent, respectively, of the clinical samples; 26.5 per cent of the clinical samples produced no growth. The most common isolates from the samples with high cell counts were coagulase-negative staphylococci (15 per cent), S uberis (14 per cent) and Corynebacterium species (10 per cent). Staphylococcus aureus and coagulase-positive staphylococci together accounted for 10 per cent of the samples with high somatic cell counts; 39 per cent produced no bacterial growth.     

Effects of a mastitis control programme on the incidence of clinical mastitis

Summary

The results of a mastitis control field experiment in Utrecht over three and a half years, including sevens herds with a total of 225 lactating cows are presented. Every case of clinical mastitis was examined bacteriologically. Quarter samples were taken routinely at an average interval of five weeks.

The incidence of clinical mastitis in each herd at the start of the experiment varied from 10 to 104 quarter cases per 100 cows per year. The majority of cases of clinical mastitis (33.1 per cent) occurred during the first month of lactation.

In 74.4 per cent of the lactations marked by clinical mastitis only a single case was observed during that lactation period. If the animals were on pasture during the first month of lactation, the incidence of clinical mastitis was significantly lower during this month, compared with the first month when they were housed. Str. dysgalactiae was the most common isolate from clinical cases (21.5 per cent). A total proportion of 40.3 per cent of the clinical cases were caused by cocci, 20.3 per cent by Gram‐negative bacteria and 16.0 per cent were bacteriologically negative. Of the clinical cases caused by streptococci and staphylococci, 33.3 per cent were preceded by subclinical infection, compared with 11.8 per cent of the clinical cases due to E. coli. The overall incidence of clinical mastitis in this experiment decreased from 47 to 31 per 100 cows per year.     

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.     

Viral antibodies in bovine fetuses in Argentina

In order to establish the prevalence of viral infections of the bovine fetus in Argentina, a serological survey for antibodies against viral agents currently affecting cattle in this country was conducted. Antibodies against foot-and-mouth disease virus (FMDV), bovine herpesvirus-1 (BHV-1), bovine leukaemia virus (BLV), bovine rotavirus (BRV), bovine coronavirus (BCV), bovine viral diarrhoea virus (BVDV) and parainfluenza-3 (PI-3) were investigated in a total of 315 fetal serum samples. Conventional techniques were used: indirect immunofluorescence (FMDV, BHV-1, BVDv and BCV), radial immunodiffusion (BLV), ELISA (BRV) and haemagglutination inhibition (PI-3). Antibodies against BHV-1, BVDV and PI-3 were detected in samples from fetuses in the second and third trimester of gestation, with a prevalence of 1·21 per cent (two of 165), 2·03 per cent (four of 197) and 5·08 per cent (nine of 177), respectively. Either antibodies or non-antibody factors able to bind to BRV and Bcv antigens were detected with a prevalence of 2·44 per cent (five of 205) and 4·54 per cent (five of 110), respectively. In addition, 14·68 per cent of non-specific inhibitors of PI-3 mediated haemagglutination were found. No seropositives against FMDV and BLV were detected.     

Histopathological survey of neoplasms in flat-coated retrievers, 1990 to 1998

Over the period from March 1990 to December 1998, veterinary surgeons in general practice were invited to submit tissues suspected of being neoplastic which had been removed from flat-coated retrievers. When possible, pedigree details were obtained from the owners. In addition, data were collected from flat-coated retrievers known to have suffered from a neoplastic condition and for which a histopathological report was available. A total of 1023 submissions was obtained from 782 dogs. These included 165 non-neoplastic lesions (16 per cent), 447 benign samples (44 per cent) and 411 malignant samples (40 per cent). Soft tissue sarcomas accounted for 55 per cent of the malignant samples (26 per cent of all tumour samples and 22 per cent of all submissions) with 63 per cent of them being diagnosed as undifferentiated. Carcinomas accounted for 20 per cent of malignant samples (8 per cent of all submissions). Of the benign tumours, cutaneous histiocytoma was the most common diagnosis (48 per cent of benign tumours, 25 per cent of all tumours and 21 per cent of all submissions).     

Prevalence and associations between bacterial isolates from dry mammary glands of dairy cows

To assess the prevalence and patterns of bacterial isolates, cultures were made from the dry mammary glands of dairy cows in six commercial dairy herds in the UK. Milk samples were taken from all four quarters of 480 cows at drying off and at weekly intervals from 14 days before to seven days after calving. A major mastitis pathogen was isolated from at least one quarter of 220 (45.8 per cent) of the cows and from more than one quarter of 90 (18.8 per cent) of them. During the late dry to calving period, of the 957 quarters with three culture results, a major mastitis pathogen was cultured from 236 (24.7 per cent) quarters of 186 (38.8 [corrected] per cent) cows. The most commonly isolated major pathogen was Escherichia coli, followed by Streptococcus uberis and coagulase-positive staphylococci. There were significant differences between the patterns of isolates from different farms and in different calving months, suggesting that the rate of infection was partially dependent on external conditions. The isolation of E. coli, S. uberis or coagulase-positive staphylococci from a cow during the late dry/periparturient period was associated with an increased risk of that cow being culled in the next lactation. Bayesian general linear mixed models were used to assess the associations between the different bacterial species. The probability of isolating either E. coli or S. uberis was significantly greater when the other organism was cultured in a milk sample; this was also true of coagulase-positive staphylococci and S. uberis. When Corynebacterium species were isolated from a milk sample, the probability of isolating coagulase-positive staphylococci or S. uberis decreased significantly, and when coagulase-negative staphylococci were isolated the probability of isolating coagulase-positive staphylococci was reduced.     

Microbiological studies on bacterial spectra of milk samples from healthy udder quarters and from those with increased cell counts and/or conductivity values]

The germ levels of 2,182 milk samples obtained from udder quarters with subclinical mastitis were compared to milk sampled from 2,061 udder quarters with physiological cell counts or conductivity values. Three cattle herds were involved in the test programme. No germ growth was established from 9.5 per cent of all samples taken from udder quarters with increased cell counts and conductivities and from 4.1 per cent of those samples taken from intact udder quarters. Samples taken from udder quarters with subclinical mastitis exhibited the following rises in bacteria, as compared to samples from intact quarters: staphylococci by 3.1 per cent, staphylocci in germ mixtures by 3.0 per cent, CAMP-positive streptococci by 2.2 per cent, alpha-haemolytic CAMP-negative streptococci by 0.8 per cent, anhaemolytic streptococci in germ mixtures by 0.4 per cent, beta-haemolytic streptococci by 0.5 per cent, and Pseudomonas aeruginosa by 1.4 per cent. Other germ species and mixtures exhibited declining trends along with growing subclinical affection of udder quarters. All findings so far obtained in the presence of subclinical mastitis are likely to suggest that 11.4 per cent of detected bacteria were of pathogenicity to udders. However, attempts to localise those 11.4 per cent were unsuccessful, since no significant difference could be calculated by comparison of intact with affected udder quarters. Reference is made in the discussion to primary and secondary germ levels of milk samples and their relevance to the problem and its elucidation.     

Incidence of clinical mastitis on farms with low somatic cell counts in bulk milk

A total of 1140 clinical cases of mastitis, with at least one inflamed quarter, were reported on 125 farms with somatic cell counts in bulk milk less than 150,000/ml. The average annual incidence was 17.9 cases per 100 cows and ranged from none to 80 cases per 100 cows. The microorganisms most frequently isolated were Escherichia coli (16.2 per cent), coagulase negative staphylococci (13.0 per cent), Staphylococcus aureus (9.6 per cent) and Streptococcus uberis (8.0 per cent). Only two cases of Streptococcus agalactiae were found. As the incidence of clinical mastitis increased, the proportion of S aureus also increased, while the proportions of E coli, S uberis and Streptococcus dysgalactiae remained about the same. Most of the clinical cases of mastitis occurred in early lactation, in November, December and January. However, after correction for the number of calvings per month, the incidence of mastitis was highest in the early summer months.     

Antibiotic susceptibility of bacterial isolates from corneal ulcers of dogs in Taiwan

OBJECTIVES: To analyse antibiotic susceptibility of bacteria associated with ulcerative keratitis in dogs. METHODS: Bacteria isolated from 190 eyes with ulcerative keratitis were identified, and the antibiotic susceptibility of isolates was studied. RESULTS: In total, 258 species of bacteria were isolated from the 190 eyes. Of the isolates, 78 per cent were Gram-positive and 28 per cent were Gram-negative bacteria. The most commonly isolated Gram-positive bacteria in dogs were Staphylococcus spp (49 per cent), Streptococcus spp (7 per cent) and Corynebacterium spp (7 per cent); while Pseudomonas aeruginosa (7.6 per cent) and Escherichia coli (5.8 per cent) were the commonest Gram-negative pathogens. Resistance to commonly used ophthalmic antibiotics was seen in Staphylococcus, Streptococcus, Corynebacterium, Pseudomonas and Escherichia species isolates. CLINICAL SIGNIFICANCE: Isolates from dogs with corneal ulcers in Taiwan may be resistant to several commonly used ophthalmic preparations. Ciprofloxacin showed good action against most isolates, with the notable exception of Streptococcus species. Chloramphenicol or cephalothin had the best in vitro action against the Streptococcus species isolates.     

FC-47 Comparison of four different types of stain in ear cytology

Swab cytology is one of the most useful and rapid methods to assess the presence of external infections in ear canals. Smears are generally stained with Romanowsky-type stains, with or without prior heat fixation. The aim of this study was to compare four different ways of staining ear cytology swab samples. Eight animals with ceruminous or purulent otitis externa were selected. Cotton swabs were introduced in a total of 12 ear canals, and four cytologic samples on four different slides were obtained from each swab. Glass slides were air-dried and randomly identified with the number of the ear canal and the letters A, B, C or D. Slides marked with A were heat-fixed and stained with Dip Quick^®; slides marked with B were stained without heat fixation. Slides marked with C were heat-fixed and dipped in the blue colour only; slides marked with D were stained in the blue colour only without prior heat fixation. Ten high-power fields (oil immersion) were evaluated for each slide, and keratinocytes, yeasts, bacteria and neutrophils were counted. A statistical comparison was performed with parametric (Student's t -test applied after verifying the normal distribution of the data) and nonparametric tests (Wilcoxson's and signs' tests). There were no significant differences between the four staining methods ( P  ≤ 0.05). The authors conclude that heat fixation does not improve the cytological evaluation of ear swab samples and propose a one-step dip in the blue colour only as a rapid method of staining cytological samples from ear canals.
Funding: Self-funded.     

Comparative study of the microbial profile from bilateral canine otitis externa

Fifty dogs with bilateral otitis externa were studied over a 10-month period. The exudates of both external ears were obtained, using sterile swabs, and microorganisms were isolated according to standard microbiological techniques. Antimicrobial susceptibility testing of Staphylococcus intermedius was done by the agar diffusion method. There was bacterial and/or fungal growth in all of the samples. These were all polymicrobial infections. Anaerobic bacteria were not isolated in any sample. The most common pathogens isolated were S. intermedius and Malassezia pachydermatis. A statistically significant difference (P < 0.05) was observed in the isolation pattern between the right and left ears in 34 of the 50 animals (68%). High resistance rates of S. intermedius strains to penicillin, ampicillin, erythromycin, tetracycline, and clindamycin were found. The results suggest that in bilateral canine otitis externa, each ear should be cultured separately and considered as separate units.     

Conjunctival flora observed in 70 healthy domestic rabbits (Oryctolagus cuniculus)

Conjunctival swabs were taken from both eyes of 70 healthy domestic rabbits and cultured to determine the microbial population. Bacteria were recovered from 83 per cent of the specimens. DNase-negative Staphylococcus species (57 per cent) were the most commonly recovered organisms followed by Micrococcus species (25 per cent) and Bacillus species (19 per cent). Other organisms isolated included Stomatococcus species (8 per cent), Neisseria species (8 per cent), Pasteurella species (6 per cent), Corynebacterium species (6 per cent), Streptococcus species (6 per cent) and Moraxella species (4 per cent), and other bacteria were isolated less frequently. Statistical analysis showed that there appeared to be no significant difference between the bacterial isolation rates from different breeds of rabbit. Significantly more of the swabs taken from young rabbits yielded cultivable bacteria than did those taken from rabbits over 12 months of age.     

International disease surveillance. International disease monitoring, October to December 2004

To assess whether the rates of antimicrobial susceptibility in bacteria isolated from the urine of dogs with urinary tract infections are similar to those of bacteria isolated from bitches with pyometra, the antimicrobial resistance of Escherichia coli isolated from the two groups were determined and compared. The samples were collected in Sweden between April 2002 and March 2003, and potential changes over time were assessed by comparing the results with corresponding data from 1991 to 1993. Among 80 isolates of E coli from cases of pyometra, the proportions that were resistant to the antimicrobials used in canine practice were generally low (ampicillin 10 per cent, enrofloxacin 4 per cent, gentamicin 0 per cent, streptomycin 5 per cent, sulfamethoxazole 8 per cent, tetracycline 4 per cent and trimethoprim 2 per cent) and similar to the proportions reported previously. Significantly lower proportions of resistance were recorded among the pyometra isolates than among 92 isolates from urine samples submitted by animal hospitals to ampicillin (P=0.04), streptomycin (P=0.002) and tetracycline (P=0.03), but there were no differences between the pyometra isolates and 113 isolates from urine samples submitted by animal clinics.     

Prevalence of coagulase-negative staphylococci in bovine mastitis in Zimbabwe

This study was carried out to determine the prevalence of coagulase-negative staphylococci in clinical and subclinical mastitis in commercial and small-scale farms in Zimbabwe. Thirty five quarter milk samples from clinical mastitis cases and 371 quarter milk samples from cows with subclinical mastitis were cultured for bacterial pathogens. The most frequent pathogens isolated in clinical mastitis were the enteric bacteria (31.4%), followed by coagulase negative staphylococci (22.9%) and then Staphylococcus aureus (17.1%), whereas in subclinical mastitis S. aureus (34.2%) and coagulase-negative staphylococci were (33.2%) the most common. Bacillus species were only isolated in milk samples from subclinical mastitis. Coagulase-negative staphylococci were observed in mixed infections with other bacteria in only 2.2 of the 406 milk samples from clinical and subclinical mastitis where they were isolated together with Bacillus species in 6 of the 9 mixed infection cases. About 95% of the milk samples from which 131 coagulase-negative staphylococci were isolated had correspondingly high somatic cell counts. The coagulase-negative staphylococci isolated most frequently were S. chromogenes (7.9%), S. epidermidis (7.4%) and S. hominis (5.9%). They were all associated with high somatic cell counts. All the coagulase-negative staphylococci isolates were susceptible to cloxacillin and erythromycin, and more than 90% of the isolates were susceptible to neomycin, penicillin and streptomycin. The highest resistance was to tetracycline (17.6%), followed by lincomycin (13.7%). About 8% of the isolates were resistant to both penicillin and streptomycin.