Predictors of owner response to companion animal death in 177 clients from 14 practices in Ontario

OBJECTIVE

To identify predictors of grief and client desires and needs as they relate to pet death.

DESIGN

Cross-sectional mail survey.

SAMPLE POPULATION

177 clients, from 14 randomly selected veterinary practices, whose cat or dog died between 6 and 43 days prior to returning the completed questionnaire.

PROCEDURE

Veterinary practices were contacted weekly to obtain the names of clients whose pets had died until approximately 200 clients were identified. Clients were contacted by telephone, and a questionnaire designed to measure grief associated with pet death was mailed to those willing to participate within 1 to 14 days of their pet's death. The questionnaire measured potential correlates and modifiers of grief and included three outcome measures: social/emotional and physical consequences, thought processes, and despair. Demographic data were also collected.

RESULTS

Approximately 30% of participants experienced severe grief. The most prominent risk factors for grief included level of attachment, euthanasia, societal attitudes toward pet death, and professional support from the veterinary team.

CONCLUSIONS AND CLINICAL RELEVANCE

Bivariate and multivariate analyses highlighted the impact owners' attitudes about euthanasia and professional intervention by the veterinary team had on reactions to pet death. Owners' perceptions of societal attitudes, also a predictor of grief, indicate that grief for pets is different than grief associated with other losses.

Sampling considerations for herd-level measurement of faecal Escherichia coli antimicrobial resistance in finisher pigs

The objective of this study was to determine the most efficient means of sampling faeces of finisher pigs for accurate and precise farm-level estimates of antimicrobial resistance among faecal Escherichia coli. Resistance to tetracycline and gentamicin of 8250 isolates of E. coli from 55 finisher pigs on one farm was measured with a hydrophobic grid membrane filter method. The between-pig, within-pen component of variance in resistance was large (97.5%), while between-pen, within-room and between-room components were small (2.5% and 0%, respectively). Using these resistance data, the abilities of two sampling strategies to estimate prevalence were modelled with a Monte Carlo 'bootstrap' procedure. Compositing faecal samples from several pigs before testing produced unbiased and precise estimates of prevalence and is simpler technically than individual animal testing.

Owner response to companion animal death: development of a theory and practical implications

This study used an inductive research method known as grounded theory to develop a theory to describe owner response to the death of a pet. Participants were identified from 8 veterinary clinics in Wellington Country, Ontario. Eighty percent (8 of 10) of the practices approached agreed to participate and there was a 77% (44 of 57) participation rate by clients. Nondirective interviews were conducted with participants approximately 10 days following the death of their pet, and at 3, 6, and 12 mo thereafter. The theory developed suggests that people's reactions are best described as a social and psychological search for meaning. Factors that contributed to the search for meaning included societal values and norms, the cultural milieu of pet death, and the cultural milieu of veterinary medicine. Other factors, such as the participant's personal beliefs, life stage, critical life events, and animal attributes, either alleviated or aggravated the experience. The outcome for participants grieving the death of a pet was a self-governing approach to coping with the death. Practical implications and suggestions for veterinarians are presented.

Individual and group antimicrobial usage rates on 34 farrow-to-finish swine farms in Ontario, Canada

Antimicrobial drug-use was assessed on 34 farrow-to-finish operations that marketed at least 500 hogs/yr. These operations either did not use any antimicrobials or used narrow-spectrum or broad-spectrum antimicrobials in rations of post-weaning pigs. Total antimicrobial use was measured for two months after obtaining inventories and records of all antimicrobials used. The collection of empty medication bottles and inventories of drugs on hand was convenient for producers and useful for estimating or validating recorded treatment rates, particularly for antimicrobials that were used only in one class of pig. Treatment records, however, underestimated by approximately 35% the amounts used for 27/29 farm-antimicrobial combinations. Rates of individual-pig treatment varied from 0-24.1 pigs treated/1000 pig-days, with a median of 5.29. Most individual animal treatments were given to piglets and sows at parturition and penicillin was the most commonly used antimicrobial. Gentamicin was administered to suckling piglets on 19 of the farms.

Associations among antimicrobial drug treatments and antimicrobial resistance of fecal Escherichia coli of swine on 34 farrow-to-finish farms in Ontario, Canada

Logistic regression was used to model associations between antimicrobial treatment and resistance among fecal Escherichia coli of finisher pigs at the farm level. Four sets of potential risk factors representing different levels of refinement of antimicrobial use on farms were modelled on resistance to antimicrobials. Final models for each antimicrobial were constructed from treatment and management variables significant on initial screening, and corrections for overdispersion were made. In general, in-feed antimicrobial treatment of pigs was more consistently associated with an increased risk of resistance than individual-animal treatment. Antimicrobial treatment in starter rations was significant in final models of resistance to ampicillin, carbadox, nitrofurantoin, sulfisoxizole, and tetracycline. Treatment in grower-finisher rations was significantly associated with resistance to ampicillin, spectinomycin, sulfisoxizole, and tetracycline. There was little evidence that in-feed antimicrobials increased the risk of resistance to gentamicin, which is a drug used only for individual-pig treatment in this study population. These results suggest that antimicrobial medication of rations of post-weaning pigs selects for and maintains antimicrobial resistance among E. coli of finisher pigs. Although resistance was common on farms that did not medicate rations of post-weaning pigs, the results indicate that antimicrobial use does increase the risk of resistance to the antimicrobials studied.

Prevalences of resistance to seven antimicrobials among fecal Escherichia coli of swine on thirty-four farrow-to-finish farms in Ontario, Canada

Fecal specimens were composited and a hydrophobic-grid membrane-filter method was used to measure antimicrobial resistance to ampicillin 16 micrograms/ml, carbadox 30 micrograms/ml, gentamicin 4 mu/ml, nitrofurantoin 32 micrograms/ml, spectinomycin 16 micrograms/ml, sulfisoxazole 32 micrograms/ml and tetracycline 8 micrograms/ml among 8119 Escherichia coli isolates from 68 fecal samples collected on 34 farrow-to-finish swine farms marketing over 500 hogs/yr. The overall prevalences of resistance to antimicrobials among these isolates were: ampicillin 29%, carbadox 3.5%, gentamicin 0.6%, nitrofurantoin 27%, spectinomycin 28%, sulfasoxizole 38% and tetracycline 71%. Thirty to seventy-six per cent of the variations in prevalences were explained by between-farm differences.

Antimicrobial drug use and related management practices among Ontario swine producers

A mail survey of swine producers in Ontario was undertaken during 1991 to describe the types, frequency, and motives for antimicrobial use. Two hundred operations that marketed fewer than 350 hogs per year, and 800 that marketed more than 350 per year were sent questionnaires, 63% of which were completed and returned. Most operations (86%) added antimicrobials to starter (weanling pig) rations, while fewer (29%) added these drugs to finisher pig rations. The most commonly used antimicrobials were tylosin, carbadox, and furazolidone in weanling pigs, and tylosin, lincomycin, and tetracycline in finishers. Water medication of grower-finisher pigs was practised on 25% of farms; 80% of farms had injected at least some grower-finisher pigs with antimicrobials in the 12 mo preceding the survey. Approximately 20% of operations that added antimicrobials to finisher rations did so for growth promotion purposes only, while others used them for disease treatment, prevention, control, or a combination of reasons. Among those not using antimicrobials in finisher rations, 83% did not believe they were necessary and 37% were concerned about the potential for residues in marketed hogs.

Measurement of antimicrobial-resistant Escherichia coli in pig feces with a hydrophobic grid membrane filter interpreter system

Hydrophobic grid membrane filter technology was used to measure resistance among Escherichia coli in pig fecal samples to ampicillin, sulfisoxazole, and tetracycline. The method accurately measured resistance, with sensitivities ranging from 96.5 to 99.5% and specificities ranging from 87.0 to 98.3%, and it identified E. coli with 96% confidence.

Impact of stocking density, breed, and feathering on the prevalence of abdominal skin scratches in broiler chickens

Associations between abdominal skin scratches and stocking density, strain of birds, and degree of feathering were investigated in a clinical trial. Four hundred eighty 1-day-old male broiler chicks from two different strains (A and B) were assigned to four groups: 1) high density (0.07 m2/bird) and strain A, 2) high density and strain B, 3) normal density (0.14 m2/bird) and strain A, and 4) normal density and strain B. Birds were examined for scratches and feathering at 28, 35, and 42 days of age. Two outcomes were considered for scratches: presence (yes/no) and severity (severe [if a deep cut or at least three superficial cuts were present]/not severe). Only the examination at 35 days of age was blind. The outcome "scratches" was significantly associated with stocking density at all ages (P < or = 0.0001), strain A at 28 days of age (P = 0.0480), and poor feathering at 35 days of age (P < or = 0.0001). The outcome "severe scratches" was significantly associated with stocking density at 35 (P = 0.0003) and 42 days of age (P = 0.0021), strain A at 35 (P = 0.0089) and 42 days of age (P = 0.0306), and poor feathering at 35 days of age (P = 0.0018). Stocking density, strain of birds, and degree of feathering could be considered as potential risk factors for abdominal scratches in broiler chickens.

A prospective study of cellulitis in broiler chickens in southern Ontario

This study investigated the associations among cellulitis and hatchery, farm, and abattoir factors. Forty-four broiler flocks from 24 farms located in southern Ontario were followed from hatching to processing. Poisson regression was used to analyze the data. Cellulitis as a count outcome (CELLCOUNT) was significantly associated (P < or = 0.05) with the hatchery of origin, strain of birds, farm size, type of litter, lighting system, total down time, prevalence of abdominal scratches, Escherichia coli-related conditions (SEROSITIS), ascites, and valgus varus deformity. However, only farm size, abdominal scratches, SEROSITIS, ascites, and valgus varus deformity were significant (P < or = 0.05) after adjusting for clustering. No significant associations were found between cellulitis and source of eggs, sex, average bird weight, feed company, growth promoter, or stocking density. Factors significantly associated with cellulitis in this study could be considered as potential risk factors for cellulitis in broiler chickens in southern Ontario.

Farm management risk factors associated with cellulitis in broiler chickens in southern Ontario

A mail survey of 171 farms with broiler chicken flocks processed in a single processing plant in southern Ontario was conducted during the period July-August 1993 as part of a retrospective study. The population farm prevalence of cellulitis was 31/10,000 birds. The survey provided information about the management of broiler chickens in southern Ontario and allowed investigation of the association between cellulitis and management risk factors. Univariate and multivariate analyses were performed to examine the relationship between a binary outcome (high/low prevalence) and management risk factors using logistic regression. Cellulitis was positively associated (P < or = 0.05) with male and mixed (males and females) flocks, use of straw as litter, certain feed companies, use of zinc bacitracin as a growth promoter, and other diseases diagnosed at the processing plant. Total down time was negatively associated with cellulitis.

Description of cellulitis lesions and associations between cellulitis and other categories of condemnation

A total of 110 broiler flocks processed in a single processing plant in southern Ontario were studied for purposes of describing the cellulitis lesions and investigating possible associations between cellulitis and other categories of condemnation at the processing plant. Two hundred and ninety-five carcasses condemned for cellulitis were examined. They came from 65 of the 110 flocks. The lesions tended to be unilateral with most carcasses (87%) having one lesion. The majority of the lesions (92%) were located on the abdomen. Almost 65% of the lesions were large (> or = 8.1 cm2), and 27% were medium (2.1-8.0 cm2). On the basis of gross appearance, 69% of the lesions were classified as severe, 26% moderate, and 5% mild. Of 149 lesions examined histologically, 74% were classified as chronic, 21% ongoing, and 5% mild-acute. Condemnation data from the 110 broiler flocks were analyzed using Poisson regression. Simple relationships were examined between a count outcome (number of cellulitis-condemned carcasses per flock) and other categories of condemnation and average bird weight. Cellulitis was significantly associated with average bird weight (P = 0.0018), Escherichia coli-related conditions (SEROSITIS; P < or = 0.0001), ascites (P = 0.0004), cyanosis (P < or = 0.0001), valgus varus deformity (P < or = 0.0001), REJECT (combined carcass condemnations for bruising, mutilation, and contamination; P = 0.0003), and the interaction terms "average bird weight and ascites" (AVWT*ASCIT; P < or = 0.0001) and "average bird weight and cyanosis" (AVWT*CYAN; P < or = 0.0001). Average bird weight, SEROSITIS, ascites, cyanosis, valgus varus deformity, and AVWT*ASCIT were the only significant factors after adjusting for clustering. No association was observed between cellulitis and emaciation and dead on arrival. Variables significantly associated with cellulitis in the multivariate analysis could be considered as potential predictors. These predictors may share common risk factors predisposing broiler chickens to cellulitis.

Postoperative complications of elective surgeries in dogs and cats determined by examining electronic and paper medical records

Postoperative complications (POC) that developed in dogs and cats that underwent elective ovariohysterectomy, castration, and declaw at a veterinary teaching hospital were determined by examining the computerized abstracts of the medical records and by examining a random sample of the paper medical records. When the computerized abstracts were examined, POC were found to have occurred in 62 (6.1%) of 1,016 dogs. One dog died and 6 others developed major complications. Postoperative complications were found to have occurred in 38 (2.6%) of 1,459 cats. Two cats died and 1 was euthanatized. Four other cats developed major complications. Complete paper medical records for 218 dogs and cats were examined. When the paper medical records were examined, the proportions of dogs and cats with POC were 19.4% and 12.2%, respectively. These proportions were 4 to 7 times higher than when the computerized abstracts were the data source. Results of this study indicate that the frequency of clinically relevant POC of elective surgeries in dogs and cats is substantial. Examination of the computerized abstracts of medical records at this hospital allowed us to rapidly identify cases that could be included in the study but the frequency of POC would be significantly underestimated if paper records were not also assessed.

The pattern of fatal fibrinous pneumonia (shipping fever) affecting calves in a large feedlot in Alberta (1985-1988)

Data from a retrospective field study were used to describe the epidemiology of fatal fibrinous pneumonia as it affected beef calves entering a large commercial feedlot in southwestern Alberta during the fall months of y 1985 to 1988. A chute-side computer system was used to record processing and health data on 58885 calves during this period. The large annual variation (10%-57%) in the proportion of total mortality due to fibrinous pneumonia indicated that crude mortality cannot be used in epidemiological studies as a surrogate measure of fibrinous pneumonia mortality. Yearly epidemic curves for fatal fibrinous pneumonia were very similar, with a short time interval (median, 19-22 d) between arrival and fatal disease. Fully 75% of the calves that died of fibrinous pneumonia already were sick within 2 weeks of arrival. Studies of the biological, environmental, and population factors that are present before and shortly after arrival at the feedlot are needed to identify strategies for reducing the incidence of fatal fibrinous pneumonia.

Effect of transportation on fatal fibrinous pneumonia and shrinkage in calves arriving at a large feedlot

A retrospective, epidemiologic field study was performed to determine whether calves that were transported greater distances from the auction market to the feedlot were at significantly higher risk of developing fatal fibrinous pneumonia (shipping fever). The study involved all 45,243 springborn steer calves that were purchased from auction markets and moved into a large commercial feedlot between September 1 and December 31 over a 4-year period (1985-1988). For all 4 years of the study, the distance calves were transported from the market to the feedlot and their shrinkage or subsequent death loss from fibrinous pneumonia were not correlated. The risk of fatal fibrinous pneumonia for calves arriving from nearby markets was just as high as that for calves transported much greater distances. The results suggested that calves can be purchased from more distant markets without having to discount their price for higher expected death losses. Differences between short and long hauls explained little, if any, of the variation among truckloads of calves in the risk of fatal fibrinous pneumonia.

Effect of pretransit mixing on fatal fibrinous pneumonia in calves

A retrospective, epidemiologic study was performed to quantify the mixing of calves from various sources at auction markets, and to determine whether mixing at the markets and the risk of fatal fibrinous pneumonia (FFP) at the feedlot were associated. In this study, 32,646 spring-born steer calves that entered a single large feedlot during the fall seasons between 1985 and 1988 were traced back to their originating auction market, and sales tickets were used to measure the number of farm sources that contributed to each truckload of calves. Individual cow/calf producers contributed a median of only 2 calves/truckload arriving at the feedlot in this study. An average truckload of 60 steers comprised calves from as many as 20 to 30 farms. The degree of mixing varied little over time and could not, therefore, be used to explain the large variations in FFP risk during different months and different years of the study. However, variation in the degree of mixing of calves from various sources at the markets evidently was responsible for differences in FFP risk among truckloads assembled by different buyers. When truckloads were grouped by buyer, FFP risk and mean number of calves per source were negatively correlated in 1986 (r = -0.67, P = 0.099), and in 1987 (r = -0.90, P = 0.002). These variables also were negatively correlated in 1988 (r = -0.56), although the correlation was not significant. The positive linear relationship between mixing of calves in truckloads supplied by different buyers and subsequent FFP risk suggested that veterinarians and feedlot owners should more aggressively observe and treat calves from truckloads that were highly mixed.(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of time of year, weather, and the pattern of auction market sales on fatal fibrinous pneumonia (shipping fever) in calves in a large feedlot in Alberta (1985-1988)

A total of 58,885 spring-born calves entering a large commercial feedlot in southwestern Alberta were studied to examine the associations between shipping fever mortality and the pattern of calf sales at the auction markets, time of year, and weather. The observational study followed calves purchased from 42 auction markets in the 4 western provinces between September 1 and December 31 in each of the years from 1985 to 1988. Calf sales at the auction markets consistently peaked during the last week of October and the first week of November. Calves entering the feedlot in November had a risk of fatal shipping fever 2 to 8 times greater than calves entering in September or December. The pattern was the same for all 4 years, with maximum risk occurring 2 to 4 weeks after the peak time for calf sales at the markets. A number of factors could have contributed to this pattern, including changes in transport truck availability, changes in the density of calves at the markets, changes in population dynamics at the feedlot that affected feedlot crew efficiency, and weather. The finding that the risk of fatal shipping fever appears to increase significantly as the feedlot fills with calves in the fall deserves the attention of feedlot owners, so they can design their treatment strategies appropriately, and of researchers, who may gain useful knowledge about the natural history of the disease by investigating why this change in risk occurs.

Prevalence of bovine parvovirus infection in Ontario dairy cattle

Studies were conducted to determine prevalence and dynamics of bovine parvovirus (BPV) infection. Dairy cows from 29 randomly selected herds in southwestern Ontario were tested twice, one year apart, for the presence of hemagglutination inhibition (HI) antibodies against BPV. Fifty-one percent of 1141 cows tested had BPV-HI titers > 1:32. One year later, the seroprevalence was 83% in 1131 cows from the same farms. The herd mean seroprevalence was 49% and 86% for the year-1 and year-2 samples, respectively. Evidence of BPV infection was found in 96% (27/28) of herds in year-1 and 100% of herds in year-2. A comparison of titers from 716 cows tested twice showed evidence of frequent BPV infection. Sixty-two percent of 326 animals selected in a systematic manner from 40 Guelph area dairy farms had BPV-HI titers > 1:32. The herd mean seroprevalence was 64% Two herds had no animals with titers above the critical titer (1:32) while in one-quarter of the herds all animals exceeded the critical titer.

An epidemiological investigation of pet ownership in Ontario

An epidemiological study was undertaken to elucidate factors associated with pet ownership. The study utilized questionnaires that were mailed to a systematic random sample of 700 households in the city of Guelph and Eramosa township. Reasons for ownership were analyzed by factor analysis while differences between owning and nonowning households were investigated using logistic regression. Sixty-five percent of dogs and 71% of cats were neutered. Only 2% of urban and 3% of rural dogs had never been vaccinated, compared to 12% and 17% for urban and rural cats. Families that included preschoolers were less likely to own pets, as were those from an urban area. The highest scoring reason for ownership was "companionship," followed by "love and affection" and for the "benefit of the children". The highest ranked reason for nonownership was "pets are a problem when I go away," followed by "I don't have enough time to devote to a pet" and "poor housing".

Antibiotic residues (bacterial inhibitory substances) in the milk of cows treated under label and extra-label conditions

The objectives of this study were to describe the depletion pattern of antibiotic residues (microbial inhibitory substances) from the milk of cows treated under field conditions of clinical disease and antibiotic administration, including both label and extra-label use, and to determine if the type of extra-label use, the route of administration, and the drug used were factors associated with prolonged shedding of residues in milk.Milk samples from 138 cows, treated with a variety of antibiotic products on farms in southwestern Ontario in 1989 and 1990, were collected before treatment and for six days after cessation of treatment. Samples were tested for antibiotic residues with the Brilliant Black reduction test (BR-test) and the Bacillus stearothermophilus var calidolactis disc assay. In 13/138 (9.4%) of cow treatments, at least one milk sample was positive on both antibiotic residue tests after the label milk withholding time for the drug(s) used. In ten of these instances, the antibiotics were administered in extra-label fashion and in three the drugs were reportedly used according to label instructions. Extra-label use of antibiotics was significantly associated with increased risk of antibiotic residues in milk beyond the label withholding time. No significant differences in risk were observed among the various antibiotic products used in the study.The farms involved in this study were selected on the basis of their proximity to our laboratory; therefore, the frequency of antibiotic residue detection after withholding times may not be indicative of the provincial or national situation. If farmers and veterinarians find themselves in a situation where extra-label use of an antibiotic is necessary, use of an alternative antibiotic that can be used at label dose and with a known withdrawal time may avoid a problem with residues.

Implementation and use of a microcomputer-based management information system to monitor dairy herd performance

A microcomputer-based herd management information system was implemented as part of the herd health program provided to 13 dairy clients by the Ontario Veterinary College, University of Guelph. The study was conducted over a two year period. Data were collected from on-farm event diaries, veterinary visit reports, and production testing information. Selected indices of reproduction, udder health, production, and heifer performance were reported. It was concluded that the implementation of a microcomputer-based information management system, operated as a bureau service, was feasible. However, limitations to the implementation in veterinary practice were identified.

Attitudes and expectations of producers to the use of a microcomputer-based management information system to monitor dairy herd performance

The attitudes and expectations of producers toward the use of a microcomputer-based herd management information system were assessed. The study was conducted over a two-year period, beginning in January 1986, and was operated as a bureau service. The implementation and use of the program are described elsewhere. Pre- and posttrial questionnaires were administered to assess producer attitudes. We found that the monthly analysis reports were used in the management of the dairy farms and were found to be a useful management tool. The majority of producers indicated a willingness to pay, on average, $6.86/cow/year for such a service.

Associations between dairy production indices and lipoarabinomannan enzyme-immunoassay results for paratuberculosis

Data from an epidemiological study in Ontario, involving 304 dairy herds, were used to identify associations between selected production indices and lipoarabinomannan antigen serological test results for paratuberculosis (LAM-ELISA). Analyses were conducted at both the herd and individual cow levels of organization. After analytically controlling for management and cow factors in the respective regression models, positive serological paratuberculosis status (as defined by the LAM-ELISA test), was associated with higher milk somatic cell counts at both the herd average (p less than 0.01), and individual cow levels of organization (p less than 0.0001). In contrast, LAM-ELISA test results were consistently not associated with calving intervals in either the herd average or individual cow level analyses. Associations between LAM-ELISA results and milk production were inconsistent. No associations were found at the herd level of organization, and LAM-ELISA results were not associated with a change in breed class average (BCA) for milk, between the previous and the most recent lactations of individual cattle. However, at the individual cow level, LAM-ELISA results were positively associated with higher milk production as measured by the current BCA (p less than 0.05), and individual cow average kg of milk produced per year of life since two years of age (p less than 0.0001).

An evaluation of selected screening tests for bovine paratuberculosis

The objective of this study was to evaluate the performance of the lipoarabinomannan antigen enzyme-linked immunosorbent assay (LAM-ELISA), carbohydrate antigen complement fixation (CH-CFT), and protein D antigen agar gel immunodiffusion (D-AGID) tests for bovine paratuberculosis, relative to histopathology, and to culture and isolation of Mycobacterium paratuberculosis from tissues and feces. Samples for test evaluation were collected from four sources including blood and tissues from 400 cull cows at three abattoirs in Ontario, blood and feces from a paratuberculosis survey of cattle from 120 dairy farms in Ontario, a serum bank containing samples from cattle from Ontario and Québec, and a bank of sera from cattle from Pennsylvania and the northeastern United States. The data were analyzed using receiver operator characteristic curves, estimates of relative sensitivity and specificity, and kappa statistics of agreement between tests. The LAM-ELISA performed significantly better than both the CH-CFT and the D-AGID tests. The LAM-ELISA was better at predicting fecal shedding status than tissue infection. However, the LAM-ELISA also had limitations. When interpreted as positive or negative (+/-), at a critical optical density of 0.675, its sensitivity and specificity relative to bacteriology were 49% and 87% respectively. Although the serological tests examined in this study provided some information, they did not predict well the infection status of individual animals.

An epidemiological study of paratuberculosis in dairy cattle in Ontario: study design and prevalence estimates

An observational study involving 304 dairy herds and three abattoirs was conducted between 1986 and 1989 to investigate the epidemiology of paratuberculosis in dairy cattle in Ontario. The objectives of this paper were to describe the method of data collection for the study, to present descriptive production statistics and to present estimates of the prevalence of paratuberculosis among dairy cattle in Ontario. Mycobacterium paratuberculosis was isolated from the distal ileum and/or the ileocecal lymph node of 5.5% of 400 cull cows. Based on a lipoarabinomannan antigen enzyme-linked immunosorbent assay (LAM-ELISA) on sera, the predicted true prevalence of paratuberculosis among 14,923 dairy cattle from 304 herds, was 6.1%. Nineteen percent of 2,943 fecal cultures were uninterpretable because of overgrowth with contaminating bacteria or fungi. It was concluded that the true prevalence of paratuberculosis among dairy cattle in Ontario was no greater, and may be less than the true prevalence among dairy cattle from various regions of the United States. However, at a practical level, for the purposes of trade policy, the present study suggests that the functional prevalence is very similar in the two countries.

Antibiotic residue prevention methods, farm management, and occurrence of antibiotic residues in milk

The objective of this study was to determine associations among the occurrence of antibiotic residues in bulk milk and various farm management practices. Ninety-four dairy farms were visited after antibiotic residues were detected in samples of their bulk milk (case farms) along with an equal number of residue-free farms (controls). Farmers completed questionnaires designed to elicit details of management practices used on farms and methods employed for prevention of antibiotic residues. Factors were initially examined unconditionally for statistical association with occurrence of residues; then multivariate associations were determined using multiple logistic regression. After adjusting for herd size in a logistic model, the risk of residues in milk was observed to increase in association with the frequent use of part-time labor in the milking of cows. The risk of residue occurrence was decreased in association with the use of milk residue test kits, when the farmer believed that increasing the dose of antibiotic required an increase in the withholding time of milk, and when tie stall and pipeline milking systems were used rather than milking parlors or tie stall and dumping station systems.

A benefit cost analysis of dry-cow mastitis therapy in Ontario dairy herds

Data collected from 297 dairy farms in Ontario were analyzed to investigate the economic consequences of using dry-cow antibiotic therapy, and to demonstrate the elements of an economic evaluation. Benefit/cost ratios ranged from 0.5 to 31.0 depending on the methods used to assess the benefits of therapy. In general, within the assumptions outlined in this analysis, dry-cow therapy was found to be economically advantageous. However, many factors can influence milk production and somatic cell counts. In this observational study, it is possible that some such factors were confounded with the use of dry-cow therapy, and may have biased the estimates of economic impact.

Tail tip necrosis in Ontario beef feedlot cattle

Studies were performed to establish the prevalence and importance of tail tip necrosis in the southern Ontario beef feedlot industry and to characterize the gross appearance and histopathology of the condition. In a mail survey, 96% of 71 feedlots with slatted floors, but only 5% of 184 feedlots with solid floors, reported a problem with tail tip necrosis from 1982-1986. Treatments reported included antibiotics, amputation of the tail (therapeutic or preventive), and slaughter. Lameness was associated with tail tip necrosis.A scoring system for severity of necrosis was developed. Repeated inspections revealed that mild lesions were unlikely to progress to more severe stages. Histological alterations such as perivascular edema and hemorrhage, dermal scarring, follicular atrophy, and paucity of leukocytes were compatible with cutaneous ischemia.Of 441 tails inspected at slaughter plants, 34.5% were affected, with 3.4% involving skin lacerations and infection, and 4.3% amputated before slaughter.

Epidemiology of Haemophilus somnus in young rams

The prevalence of Haemophilus somnus in the prepuce of young rams was examined. Of 473 rams entering Record of Performance (ROP) stations at 50 days of age, 43 (9.1%) were positive. Average daily gain was not affected by Haemophilus status, but was influenced by breed of ram. Suffolks were predicted to gain 0.515 kg daily compared to 0.427 kg for a group combining all other breeds. Using logistic regression to identify risk factors for individual H. somnus infection, rams in 1989 were 0.382 times as likely to be infected as rams in 1988, and Suffolks were 0.314 times as likely to be infected as the other breeds group, but these factors were not significant at the flock level. Of 80 eligible flocks of origin, 22 (27.5%) were classified as infected with H. somnus, based on rams submitted to the ROP station. Infected flocks contributed 133 rams, 43 (32.3%) of which were positive. There was no association between H. somnus status and lambing percent of the percent of abortions and stillbirths, but there was a statistically significant association with the percent of ewes which failed to lamb. In the model developed, 6% of the bred ewes in noninfected flocks failed to lamb, compared to a rate of 12% in infected flocks. These results suggest H. somnus may influence ewe fertility earlier, rather than later in gestation. Purchasing replacement animals and having cattle on the farm were risk factors for Haemophilus infection in the flock. Where replacements had been purchased within the previous year, the risk of flock infection rose 8.5 times, and on farms having cattle as well as sheep, the risk rose 13.2 times.(ABSTRACT TRUNCATED AT 250 WORDS)

The prevalence of verocytotoxin-producing Escherichia coli and antimicrobial resistance patterns of nonverocytotoxin-producing Escherichia coli and Salmonella in Ontario broiler chickens

The prevalence of verocytotoxin-producing Escherichia coli and Salmonella in Ontario broiler chickens was determined by culturing cloacal samples from 500 individual birds selected from 50 poultry farms. Resistance to antimicrobials was determined for each of the isolates. In addition, abattoir and farm-level management data were obtained to evaluate variables that may be considered risk factors for infection. The variables selected included: Percentage of birds condemned at slaughter, percentage of birds dead-on-arrival, bird weight, truck number, farm size, hatchery source, litter source and type, feed source, mortality levels, type of water drinker, water sanitization, down time, barn clean out and history of antibiotic treatment. None of the cloacal samples revealed the presence of verocytotoxin-producing E. coli, though 19/500 (3.8%) contained Salmonella organisms. Nine different Salmonella serotypes were isolated; the most common being S. hadar, S. heidelberg and S. mbandaka. Resistance to tetracycline and streptomycin was common among Salmonella (63%) and E. coli (25.2%) isolates. Resistance to two or more antimicrobials occurred in 420/500 (84%) of the E. coli isolates. No statistically significant associations between abattoir or farm-level management variables and the Salmonella-status of farms were demonstrated.

Factors associated with average daily gain, fever and lameness in beef bulls at the Saskatchewan Central Feed Test Station

Data obtained from the Saskatchewan Central Feed Test Station in Saskatoon, Saskatchewan, Canada were examined for evidence of factors related to average daily gain and the diseases occurring in 326 beef bulls during the 1983-84 test. Average daily gain was found to be significantly associated with breed, pen assignment and initial test weight but was not associated with disease or age upon arrival at the test station. Lameness was associated with breed and initial weight, while fever (suspected respiratory disease) was associated with age. The predicted odds of lameness was approximately seven times greater in the animal with the heaviest as compared to the lightest initial test weight and the predicted odds of fever was approximately five times greater in the youngest as compared to the oldest animal.

The prevalence of leptospirosis and its association with multifocal interstitial nephritis in swine at slaughter

An abattoir survey was undertaken to determine the prevalence of leptospirosis and its association with lesions of multifocal interstitial nephritis (so-called "white spotted kidneys") in swine at slaughter. Both cross-sectional and case-control study designs were used. Of 197 kidneys from hogs randomly selected at slaughter, 11 (5.6%) had generalized grey-white foci typical of multifocal interstitial nephritis (MFIN). Antibody titers greater than or equal to 1:80 against Leptospira pomona were detected in nine (4.6%) hogs and against L. bratislava in 63 (32%) of these hogs. Leptospira pomona (kennewicki) was detected by immunofluorescence in 5/197 (2.5%) of randomly selected hogs. Leptospires identified as genotype kennewicki were isolated from six (9.8%) of 61 kidneys cultured. Leptospira bratislava was not detected by immunofluorescence or culture. There was a highly significant (p = 0.00) and strong association (odds ratio (OR) = 195) between high L. pomona titer (greater than or equal to 1:80) and the presence of leptospires in the kidneys, as detected by culture. There was also a significant (p = 0.046) and strong (OR = 8.10) association between multifocal interstitial nephritis and the presence of renal leptospires as detected by culture. The association between leptospiral titer and MFIN lesions in the prevalence survey group of animals was statistically significant (p = 0.031), but this association was not significant in the case-control study group (p = 0.071) The failure to identify L. bratislava despite serological evidence of infection suggests that some of these seropositive animals may have been transiently infected at an early age, that serological findings were falsely positive, or that immunofluorescence and isolation attempts failed to detect L. bratislava if they were indeed present in the kidneys.(ABSTRACT TRUNCATED AT 250 WORDS)

An assessment of condemnations of broiler chicken carcasses

An epidemiological study was conducted to assess the rates of condemnation and the diagnoses made on condemned broiler chicken carcasses in a federally-inspected abattoir. The first objective was to determine the predictive value of a positive test: the proportion of birds that were truly unfit for human consumption among condemned carcasses. The second objective was to assess the degree of agreement between diagnoses made in the abattoir and diagnoses determined by a detailed gross postmortem examination on the same condemned carcasses. A two-stage convenience sampling technique was used to obtain the birds needed. Fifteen lots of birds were selected and within each of these, approximately 45 condemned carcasses were selected for a total of 680. All the diagnoses made on these birds at the abattoir were recorded and the carcasses individually identified. The sampled carcasses were transported to the Ontario Veterinary College where a panel of three federal veterinarians independently judged whether the birds were fit for human consumption. In addition, a detailed gross postmortem examination was conducted on each carcass. An overall predictive value of a positive test of approximately 70% was found. The degree of agreement among members of the panel of examiners was also tested. The overall agreement was good (Kappa = 0.62 between examiners 1 and 2 and 0.51 between examiners 1 and 3). However, carcasses condemned for specific conditions at the abattoir, namely valgus varus deformity, mutilation, cellulitis and hepatitis showed no agreement beyond chance, while other carcasses condemned for conditions such as cyanosis and bruising showed poor agreement concerning their disposition for at least one pair of examiners.(ABSTRACT TRUNCATED AT 250 WORDS)

An assessment of the utility of microcomputers and dairy herd management software for dairy farms and dairy practices

Microcomputer systems were placed in three veterinary practices each serving three farms (bureau), and onto nine dairy farms (on-farm). Over a twenty-four week period, the utilization of the computer system and the DHM software was monitored. The on-farm system was more costly in terms of equipment and technical support effort, but the information was utilized to a greater extent than it was by the bureau participants who had invested more user time per cow. Note that actual time will vary with the software program used. The farmers indicated that they wished to have access to the information offered by the software. ;Computer phobia' was not found to be a problem. The expectations of the computer system and its benefits generally remained high. In general, the information available through the microcomputer system and the DHM software was found to be useful to both the dairy farmers and the veterinarians in this study.

The Dairy Herd Management System. Application to dairy herd reproductive management as a bureau and on-farm system

This article describes the field use of the Dairy Herd Management System Microcomputer software. The practical experiences gained from the use of the program in dairy reproductive management are discussed for operation both as a bureau service and as an on-farm system.

Perceived Usefulness of the Collection of Subclinical and other Disease Entities Detected at Slaughter

Based on a survey of 1820 Ontario pork producers and 16 veterinary members of the Ontario Swine Practitioners Association, condemnation/demerit data, while viewed as potentially valuable, are seldom, if ever, utilized in the provision of herd health programs. We found, however, that: 1) 89.4 percent (SD 1.04 percent) of producers and all veterinarians would use the disease information made available by a computerized system that would collect and report on subclinical and other disease entities detected during the slaughter of hogs; 2) Iesion diagnosis should be as detailed as possible and report on severity of disease; and 3) with the exception of those producers who ship larger numbers of hogs to market for which reports were wanted for each kill, monthly reports would be adequate.Written comments by producers expressed concerns about confidentiality of individual herd data, costs for the information/service, and veterinary expertise in the interpretation of findings.

Factors associated with productivity in Canadian sheep flocks

A mail survey of Canadian sheep flocks registered on the Record of Performance program was conducted, and the association of management practices and diseases with productivity was studied using multiple regression techniques. The relationships between management practices and diseases of lambs which were associated with production were also investigated using discriminant analysis. Flocks in the maritimes had a lower average flock productivity than those in Ontario-Quebec and the western provinces. In purebred flocks, the average adjusted weight at 100 days of age was higher than in other types of flocks, and the prevalence of scours was lower. At the herd level, the rates of pregnancy toxemia and vaginal prolapse were associated with heavier lambs, while the average daily weight gain between 50 and 100 days of age was lower in herds affected by scours and starvation. Using pasture and bush as winter housing was also detrimental to lamb productivity. No management practices discriminated between case and control flocks for scours and starvation in lambs. It was concluded that the reasons for the geographic differences should be investigated as should the management differences between purebred and other producers. Prevention of scours and starvation in lambs should be given priority in order to increase productivity.

Selenium content in the hair of newborn dairy heifer calves and its association with preweaning morbidity and mortality

Hair samples from newborn heifer calves on Holstein dairy farms in southwestern Ontario were analyzed for selenium content by means of instrumental neutron activation analysis. The mean selenium level in the hair of calves which subsequently died at less than six weeks of age did not differ from selenium levels in the hair of calves matched by farm and birthday (overall mean 0.28 ppm). The mean selenium level in the hair of calves which were not treated for disease during the first four weeks of life was 0.42 ppm, while that from appropriately matched treated calves was 0.36 ppm; the difference between the means was significant at p = 0.054. Based on the above associations, it is suggested that higher selenium levels in newborn calves may have some protective effect against morbidity.

The effect of early calfhood health status on survivorship and age at first calving

Survival to maturity and age at first calving were studied in heifer calves from 34 randomly selected Holstein dairy farms in southwestern Ontario. Calves were divided into cohorts on the basis of treatment for pneumonia, scours, other diseases, or no treatments, during the first 90 days of life. An effect of pneumonia and scours together, over and above the effects of each disease alone, was assessed by means on an interaction term in the statistical analyses. Heifers which had been treated for pneumonia during the first three months of life were 2.5 times more likely to die after 90 days of age than heifers which had not been treated for pneumonia, after controlling for the farm effect. Heifers with a calfhood history of being treated for scours were 2.5 times more likely to be sold for dairy purposes than other calves. Heifers which had been treated for scours were 2.9 times more likely to calve after 900 days of age than other heifers, after controlling for the farm effect.

An epidemiological study of selected calf pathogens on Holstein dairy farms in southwestern Ontario

Fecal samples from calves on 78 randomly selected Holstein dairy farms in southwestern Ontario were screened for Salmonella, Campylobacter jejuni/coli, enteropathogenic Escherichia coli, rotavirus and coronavirus. Based on the observed prevalence, 22% of farms had calves infected with Salmonella, 13% with Campylobacter jejuni/coli, 41% with enteropathogenic E. coli, 19% with rotavirus and 5% with coronavirus. These estimates can be modified, using a method developed by Mullen and Prost (1983) for the World Health Organization, to account for the nature of the laboratory test used. If the test is assumed to have no false positives (that is, if an organism is detected it must be there), then the observed prevalence estimates seen on this study may greatly underestimate the true prevalence of infected premises. The use of nipple feeders for calves was associated with an increased probability of farms having calves shedding detectable fecal levels of Salmonella, E. coli, or one of the two viruses. The use of group pens was associated with an increased odds of finding C. jejuni. Calves with diarrhea on these farms tended to have increased odds of shedding rotavirus, and E. coli with the K99 antigen. However, at the farm level, none of the organisms was associated with above median levels of morbidity. Farms positive for one or other of the viruses had increased odds of experiencing calf mortality relative to virus-negative farms, and farms positive for C. jejuni/coli had decreased odds of mortality.(ABSTRACT TRUNCATED AT 250 WORDS)

A path model of factors influencing morbidity and mortality in Ontario feedlot calves

The principles of path analysis and causal modelling are discussed. Path analysis was applied to three data sets to assess the relationship between group characteristics (number per group and "mixing" subgroups of cattle, feeding-management of the group and processing factors (vaccination and prophylactic antimicrobials) and subsequent morbidity and mortality in feedlot cattle. The major findings agree with previously reported results but the timing and pathways of the effects are elaborated. In general, morbidity in week 1 was correlated with morbidity in week 2, which was correlated with morbidity in weeks 3-5. The same was generally true for mortality. In general, morbidity was not strongly correlated with mortality. Lots (unmixed groups) did not arrive in better condition, but experienced fewer subsequent health problems than mixed groups. (Silage-fed lots appeared to do poorly, however this was apparently due to the positive association between lots and vaccination, the latter being detrimental to mortality rates.) The more cattle per group, the greater the health problems in weeks 3-5 postarrival. Prophylactic antimicrobials in the water supply on arrival lead to increased health problems in the three to five week postarrival period. Antibiotic containing starter rations had a beneficial effect on health status in this period. This effect appeared to be partly due to delaying making silage the major ration component in silage-fed cattle receiving antimicrobial containing starter rations. Vaccination against respiratory disease in either of the first two weeks postarrival had detrimental direct and indirect effects on subsequent health status. Vaccination during weeks 3-5 postarrival was not significantly related to health status in that period.

Calf-related Drug Use on Holstein Dairy Farms in Southwestern Ontario

Calf-related drug use was studied on 104 randomly selected Holstein dairy farms in southwestern Ontario between October 1980 and July 1983. About 20% of dairy farmers were observed to administer antimicrobials preventively to healthy newborn calves (primarily as commercial "cocktails" of various antimicrobials, vitamins and minerals given in an oral bolus form) at some time during the year. About 30% of the farmers were observed to use vitamins (primarily vitamins A,D and E) preventively. The pattern of types of antimicrobials used preventively appeared to be different from the pattern seen for therapeutic use. Chloramphenicol was the single most commonly used therapeutic antimicrobial in this population of calves, accounting for some 30% of overall therapeutic antimicrobial use. In this study population, the prophylactic use of antimicrobials was associated with a decreased risk of being treated for pneumonia, and of dying, but an increased risk of being treated for scours. Case fatality rates for calves treated therapeutically varied, depending on the antimicrobial used and the routine of treatment. Calves treated with penicillin consistently suffered the highest case fatality rates. Case fatality rates for calves treated with chloramphenicol were considerably higher for calves treated once per day than for calves treated twice per day. For instance, calves first treated for scours with chloramphenicol, if treated once per day, suffered a case fatality rate of 22%. For scouring calves treated twice per day the case fatality rate was just under five percent. Clinical field trials of specific antimicrobials used preventively and therapeutically are required to delineate the conditions under which they might be useful.

The relationship among current management systems, production, disease and drug usage on Ontario dairy farms

The study involved 110 randomly selected dairy farms located in the Ontario, Canada counties of Bruce, Grey, Huron, Oxford, Perth, Waterloo and Wellington. Herds were classified as "intensive" and "extensive". On extensive farms, data were collected at the herd level only, while on intensive farms, data were recorded at both the individual animal and herd level. Data collection continued for approximately two and one-half years. At each visit, technicians collected production data from the most recent production recording scheme report and from the "daily log" maintained by each producer. As well as the ongoing data collection procedures, a number of supplementary data collections were made. The average 305 day milk production increased gradually during the three calendar years from 6224.6 kg in 1981 to 6443.7 kg in 1983. The average calving interval was stable at 13.2 months for all three years. The majority of cows removed from the herds were culled for beef (0.243 per animal year). The next highest removal rate was for domestic sale, followed by death, export sale and destroyed. The highest disease rate, for those conditions whose rates were based on calving, was for retained placenta (0.09 per calving), while clinical mastitis was highest for those conditions whose rates were based on animal years (0.37 per animal year). The overall crude antimicrobial dosage rate, that is, including any antimicrobial used for either prophylactic or therapeutic purposes, was 3.85 doses per animal year. The rate for therapeutic purposes only was 3.6 doses per animal year. Penicillin/streptomycin was used most often with a rate of 1.45 doses per animal year.

A field trial to evaluate the efficacy of a combined rotavirus-coronavirus/Escherichia coli vaccine in dairy cattle

A field trial was designed to determine the efficacy of a combination rotavirus-coronavirus/Escherichia coli vaccine on dairy farms in southwestern Ontario. In Part A of the trial, 321 cows on 15 farms were randomly assigned to either vaccination or placebo groups. On eight farms, 50% of the dams were vaccinated, while on the other seven farms, 80% of the dams were vaccinated. In Part B of the trial, 26 farms were randomly assigned to either a total vaccination program or to no vaccination program. Mortality, disease occurrence and weight gains were recorded on all calves for the first two weeks of life. In Part A, 23.5% of all calves were treated in the first two weeks of life, 20.9% were treated specifically for scours and 3.6% of live-born calves died. Enteropathogenic E. coli was identified on 13 of the 15 farms, rotavirus on 11 and coronavirus on ten. At least one of the three potential pathogens was found on every farm. There were no significant differences between calves from placebo-treated and vaccine-treated dams with regard to the proportion treated for all diseases, or for scours, or the proportion which died. Neither were there differences in days to first treatment for all diseases (seven days on average), days to first scour (6.7 days), duration of treatments (3.9 days for all diseases, 3.7 days for scours), or estimated weight gains (0.5 kg/day to 14 days). These results were not altered when the presence or absence of enteropathogenic E. coli, rotavirus or coronavirus on the premises was accounted for.(ABSTRACT TRUNCATED AT 250 WORDS)

Reproductive efficiency and calf survival in Ontario beef cow-calf herds: a cross-sectional mail survey

A survey of the efficiency of production of Ontario beef cow-calf herds was conducted using a stratified systematic random sample of Ontario producers. In general, about 87% of females exposed to breeding produced a live calf and 6% of these died before reaching four weeks of age. The herd to herd variation in these rates was quite large, the coefficient of variation being about 17%. The stillbirth rate was 1.7% and the abortion rate 1.2%. In general, herds in northern Ontario and herds whose owners kept breeding and calving records, had reduced livebirth rates, the latter probably reflecting accuracy of data. Herds with a restricted (less than three months) breeding season had increased livebirth rates. Herds using injectable vitamins ADE, and prophylactic antibiotics, had increased neonatal losses. Herds with a restricted calving season (less than or equal to 3 months) and/or feeding free choice salt to cows had decreased neonatal losses. Herdsize and calf mortality rate were directly related, but this did not appear to be due to increased density of cows at calving time. In herds, where calving occurred during the spring, using scour vaccines in calves was associated with increased calf mortality.

Somatic cell counts: associated factors and relationship to production

Factors affecting somatic cell counts and the association between somatic cell counts and milk production were evaluated. Data were collected from 748 Ontario Dairy Herd Improvement Corporation supervised herds that were on production and somatic cell count programs between April 1981 and March 1983. Two data files were created; one, the lactation summary file, contained one record per cow on each of 9406 Holsteins and the other, the test day file, included results of all tests during the complete lactation on each of the above cows. The latter file contained 85,236 records. Multiple curvilinear least squares regression was used to create five separate models. The dependent variables used in the models were natural logarithms (Loge) of the geometric mean of the somatic cell count for the lactation, 305 day milk production and breed class average for milk from the lactation summary file, and loge of the 24 hour somatic cell count and 24 hour milk production from the test day file. The somatic cell count at both the lactation and test day level increased with age up to approximately ten years and thereafter slowly decreased. The variable "days in milk" was not significantly associated with the lactation average somatic cell count. A curvilinear relationship was found between days in lactation at the time of test and the somatic cell count of 24 hour milk production. The somatic cell count increased until approximately 250 days in lactation and thereafter slowly decreased. It was found that the highest cell counts occurred in summer and the lowest in winter.(ABSTRACT TRUNCATED AT 250 WORDS)