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Biomedical subjects

I A Gardner

Publications and source records attributed to I A Gardner.

At least 55 records · Page 3Linked to original sources
PubMed1999

Evaluation of temporal and spatial clustering of horses with Corynebacterium pseudotuberculosis infection.

OBJECTIVE: To determine whether horses with Corynebacterium pseudotuberculosis infections that were examined at a veterinary medical teaching hospital between July 1, 1992, and June 30, 1994 had patterns of temporal or spatial clustering. ANIMALS: 134 case and 800 control horses randomly selected from all non-case horses admitted during the study period. PROCEDURES: Admission date and geographic location were determined. Scan, Cuzick & Edwards', and Knox tests were applied to determine whether case horses had patterns of temporal or spatial clustering. RESULTS: For all windows > or = 3 days (134 case horses) and > or = 7 days (subset of 69 case horses), results of the Scan test were significant. Results of Cuzick & Edwards' test were significant for all data sets. A significant spatial cluster of case horses was observed for October, November, and December 1992. Results of the Knox test were significant for temporal intervals between 7 and 56 days and spatial intervals between 4.3 and 6.5 km. Higher Knox(x) proportions were observed for temporal intervals of 0 to 7, 8 to 14, 22 to 28, and 29 to 35 days. CONCLUSIONS: Significant spatial and temporal clustering of horses with C pseudotuberculosis infection was detected. CLINICAL RELEVANCE: Analysis of the results strongly indicates that this disease is directly or indirectly (ie, short distance and time) transmitted. In addition, data analyses indicated an incubation period of 3 to 4 weeks. The disease could be transmitted through horse-to-horse contact or from infected to susceptible horses via insects, other vectors, or contaminated soil.

Animals↗
PubMed1998

Risk factors for brucellosis seropositivity of goat herds in the Mexicali Valley of Baja California, Mexico.

A case-control study was conducted in the Mexicali Valley to identify risk factors for goat-herd seropositivity for Brucella melitensis. Nineteen case herds (> or = 2 positive results with the 8% rose bengal plate test (RBT)) and 55 control herds (zero positive results in RBT), matched for herdsize and geographic location, were enrolled. Conditional logistic regression was used to construct a multivariable model of the odds of seropositivity using variables assessed in a questionnaire administered to goat ranchers. The final model for herd seropositivity included increased risk from importation of goats from other Mexican states, the presence of La Mancha breed does, and the presence of does born outside the herd. Increasing herdsize was also highly significant (p < 0.01). In addition, a significant (p < 0.05) positive association was found between the presence of seropositive dogs (as assessed by RBT) and seropositive goats on the same ranch.

Animals↗
PubMed1998

Evaluation of bluetongue virus diagnostic tests in free-ranging bighorn sheep.

Five bluetongue virus (BTV) diagnostic tests were evaluated for use in free-ranging bighorn sheep. We sampled one bighorn sheep population four times between 1989 and 1995. The tests evaluated included virus isolation (VI), polymerase-chain reaction (PCR), serum neutralization (SN), agar-gel immunodiffusion (AGID), and competitive enzyme-linked immunosorbent assay (c-ELISA). The c-ELISA, AGID and SN tests had high levels of agreement in determining serogroup exposure in bighorn sheep. We used maximum-likelihood algorithms to estimate the parameters of each diagnostic test used. Although the c-ELISA and AGID had high sensitivity and specificity, the SN had perfect specificity but lower apparent sensitivity. Due to the potential of cross-reactions among multiple serotypes, results of the SN must be interpreted with caution when assessing serotype exposure in an area where multiple serotypes are endemic. The PCR assay delineated convalescent antibody titers from more-recent infections, and consequently, was pivotal in distinguishing a different exposure pattern between the bighorn sheep and cattle in an adjacent herd. Based on an increasing seroprevalence (50% to 100%), BTV circulated through this bighorn sheep population between 1989 and 1993. This increase in seroprevalence coincided with a bighorn die-off due to BTV infection in June, 1991. An adjacent cattle herd was sampled in 1995 for comparison. The bighorn sheep and adjacent cattle had different patterns of exposure to BTV between 1994 and 1995. There was no evidence that BTV circulated through the bighorn sheep population from 1994 to 1995. In 1995, seroprevalence to BTV decreased to 72%, none of yearling bighorn was seropositive, and all of the 39 bighorn sheep were PCR-negative. In contrast, all adult cattle were seropositive to BTV by c-ELISA and SN, and 4 of the calves were seropositive; 11 of the 24 cattle were PCR-positive, including all five calves. Overall, the pattern of temporal herd immunity in the bighorn sheep appeared to follow a classic epidemic curve, with the appearance and subsequent disappearance of herd immunity coinciding with the 1991 die-off in this population. As low levels of herd immunity and high proportions of susceptible animals are key factors in the development of epidemics, this population of bighorn sheep may be at increased risk for a BTV epidemic in the future.

Animals↗
PubMed1998

Application and evaluation of a mailed questionnaire for an epidemiologic study of Corynebacterium pseudotuberculosis infection in horses.

The objective of this study is to describe the design, application and validity of a self-administered (mailed) questionnaire to collect data on potential risk factors for Corynebacterium pseudotuberculosis infection in California horses. Horses admitted to the UC Davis Veterinary Medical Teaching Hospital (VMTH) between 1 July 1992 and 30 June 1994 served as the study base for case identification and simple random sampling of 800 control horses. A questionnaire was mailed to owners of the study horses, followed by a reminder postcard and a second copy of a questionnaire. Data were collected on owner and horse identity and demographics, horse management and use, geographic location, and general health-related issues. Return pattern over time as well as differential return proportions were described. The overall return proportion was 66% (587/890), and the completion proportion 55% (491/890). The number of returns over time followed a negative binomial distribution, with over 90% of all returns being in by the end of the fifth week after mailing, and over 99% at the end of the tenth week. Some categories within the variables age (between 2 and 3 years), breed (Thoroughbred and Standardbred horses) and gender (stallions) had significantly lower return proportions than expected (differential return; p < 0.05). The profile of these horses fits a section of the racehorse population that is served by the VMTH. Age, breed and disease status information was available from the VMTH medical records and from the questionnaire, and was used to determine the validity of the survey data. There was good agreement between the data from the two sources, and we therefore concluded that the quality of the survey information was sufficient to perform a risk-factor analysis. The mailed survey provided a rapid and cost-effective method of collecting additional information to supplement existing medical records.

Animals↗
PubMed1998

Risk factors associated with Corynebacterium pseudotuberculosis infection in California horses.

A case-control study was designed using equine medical records from the UC Davis Veterinary Medical Teaching Hospital (VMTH) and data derived through a mailed survey. The objective was to evaluate the associations between horse demographics, horse-management factors, and equine Corynebacterium pseudotuberculosis infection in California. Horses admitted to the VMTH between July 1 1992 and June 30 1994 served as the study base for case identification and simple random sampling of 800 controls. A questionnaire was mailed to the owners of all horses enrolled in the study to collect data on demographics, management and health-related questions. A logistic-regression model containing age, outdoor activity level, other locations in California, insect-control measures, contact with other horses, and summer pasture was developed. The final model was adjusted for the suspected confounding variables admission type, regular teaching hospital patient and breed. Horses of age between 1 and 2 yrs and between 3 and 5 yrs, and horses in contact with other horses or horses on summer pasture had significantly increased odds (p < 0.05) of being diagnosed with C. pseudotuberculosis infection. The results support the hypotheses that the disease predominantly affects young-adult horses of all breeds and both sexes, and that management factors play an important role in occurrence of the disease. Since the existing serological test system is not reliable and destruction of infected animals is not feasible, the most-logical approach for disease prevention is the early identification and isolation of clinical cases and the implementation of management changes like improvement of stable hygiene and insect control and change of pasture practices.

Animals↗
PubMed1998

Association between long periods without high-speed workouts and risk of complete humeral or pelvic fracture in thoroughbred racehorses: 54 cases (1991-1994).

OBJECTIVE: To determine whether a two-month or longer period without official high-speed workouts (lay-up) is associated with humeral or pelvic fracture in Thoroughbred racehorses. DESIGN: Reprospective study. ANIMALS: Thoroughbred racehorses in California that were euthanatized because of a complete humeral or pelvic fracture. PROCEDURE: Age, sex, activity, number of lay-ups, number of days from a race or official timed workout to fracture, number of days from end of last lay-up to fracture, mean duration of lay-ups, and total number of days in race training were compared between horses with humeral fractures and horses with pelvic fractures. A case-crossover study was used to estimate relative risk for fracture of the humerus or pelvis occurring within hazard periods of 10 and 21 days following lay-up, compared with periods following more regular participation in official racing or timed workout events. RESULTS: Horses with pelvic fractures were more often female, older, and had 0 or > or = 2 lay-ups. Horses with humeral fractures were typically 3-year-old males that had 1 lay-up. Horses with pelvic fractures had more total days in race training, fewer days from last exercise event to fracture, and a greater number of days from end of last lay-up to fracture than horses with humeral fractures. Return from lay-up was strongly associated with risk for humeral fracture during hazard periods of 10 and 21 days (relative risk = 71 and 45, respectively). CLINICAL IMPLICATIONS: Risk of humeral fracture may be reduced if horses are cautiously reintroduced into race training after lay-up.

Animals↗
PubMed1998

Relationship between race start characteristics and risk of catastrophic injury in thoroughbreds: 78 cases (1992).

OBJECTIVE: To investigate relationships of several racehorse characteristics and race conditions with risk of a catastrophic musculoskeletal injury (CMI) resulting in euthanasia in Thoroughbreds during racing in California in 1992. DESIGN: Retrospective longitudinal study. ANIMALS: Thoroughbreds that incurred CMI during racing and all California race entrants in 1992. PROCEDURE: Necropsy records were reviewed, and race start information was obtained. Incidence risk of CMI/1,000 race entrants was estimated. Relationships between CMI during racing and race-meet, entrant age and sex, race type and length, and racing surface type and condition were evaluated by use of logistic regression. RESULTS: Incidence risk of CMI was 1.7/1,000 entrants. A higher risk of CMI was found at 2 fair race-meets, with incidence risks of 4.9 and 5.5/1,000 entrants. Risk of injury in male horses was 1.7 times greater than that in female horses, and influence of age on risk depended on race type. Risk of injury for horses 2 to 5 years old was two times greater for claiming horses than for maiden horses. Race length or racing surface type (dirt vs turf) or condition (fast, muddy, yielding) were not significantly associated with risk of CMI. CLINICAL IMPLICATIONS: Incidence of CMI was similar among 12 of 14 major and fair race-meets and among various race lengths and racing surface types and conditions, whereas incidence of CMI was influenced by entrant age and sex as well as race type. Investigators should consider controlling for age and sex, race-meet, and race type whenever possible in studies of risk of CMI.

Age Factors↗
PubMed1998

A case-crossover study of intensive racing and training schedules and risk of catastrophic musculoskeletal injury and lay-up in California thoroughbred racehorses.

The objective of this study was to investigate the relationship between intensive racing and training schedules and risk of either catastrophic musculoskeletal injury (CMI) or lay-up from racing in California Thoroughbreds. Thoroughbred racehorses that sustained a CMI during racing or training and either were subsequently euthanized or died on a California racetrack during 1991 and 1992 were studied using a case-crossover study design. Each study subject (case) provided its own self-matched control information in the form of 'typical' exposure frequency, determined or estimated from historic information. Periods of rapid average daily accumulation of high-speed exercise distance were identified for each horse from official race and training histories with a sliding 60-day window. Those window frames containing an average daily rate of distance accumulation exceeding 75th percentile cutoff values were classified as exposed frames followed by 30 days of increased risk, or hazard periods. All remaining days (excluding periods of layoff from racing) were considered non-hazard time at risk. The relative risk (RR) of CMI within 30 days following a period of rapid accumulation of high-speed exercise distance (during a hazard period) was 4.2 (95% confidence interval [CI] = 3.0, 5.8). Of these 214 cases, 84 (39%) were injured during a hazard period whereas on average only 22% of total career time at risk was hazard time for these horses. A second analysis was performed for horses with at least 1 lay-up period from racing of > or = 60 days. RR for a lay-up beginning during a hazard period was estimated for the last lay-up experienced by each horse. The RR for lay-up beginning during a hazard period was 4.8 (95% CI = 2.9, 8.1). Of these 98 cases, 32 (33%) of the lay-ups began during a hazard period whereas on average, only 22% of at-risk time up to last lay-up was hazard time for these horses.

Age Distribution↗
PubMed1998

Evaluation of North American antibody detection tests for diagnosis of brucellosis in goats.

The sensitivities and specificities of 17 antibody detection tests for brucellosis in goats were estimated. Tests evaluated included the U.S. Department of Agriculture (USDA) card test with 8% cell concentration (8%Card), USDA rapid automated presumptive test (RAP), Mexican rose bengal plate tests with 8 and 3% cell concentrations (8%RB and 3%RB), French rose bengal plate test with 4.5% cell concentration (4.5%RB), USDA standard plate test (SPT), USDA buffered acidified plate agglutination test (BAPA), USDA and Mexican rivanol tests (URIV and MRIV), USDA standard tube tests with Brucella abortus and Brucella melitensis antigens (SATA and SATM), serum enzyme-linked immunosorbent assay (ELISA), USDA cold-fixation complement fixation tests with B. abortus and B. melitensis antigens (CFA and CFM), USDA and Mexican milk ring tests (UBRT and MBRT), and a milk ELISA. Test sensitivity was evaluated by using two groups of 10 goats experimentally infected with B. melitensis or B. abortus and monitored for 24 weeks. Specificity was evaluated by using 200 brucellosis-free nonvaccinated goats from 10 California herds. The 3%RB was considered a good screening test because of high sensitivity at week 24 postinfection (90%), ease of performance, and low cost. The cold-fixation CFA and CFM had 100% specificity in the field study and were considered appropriate confirmatory tests. The milk ELISA was significantly more sensitive (P < 0.05) than the UBRT and significantly more specific (P < 0.05) than the MBRT. The milk ELISA also had the advantage of objectivity and ease of interpretation.

Agglutination Tests↗
PubMed1998

Epidemiological surveillance of rabies in Lithuania from 1986 to 1996.

Rabies has been endemic in Lithuania for centuries. The objective of this study was to evaluate rabies incidence and seasonal trends in domestic and wild animals in Lithuania from 1986 to 1996. Annual rabies reports and data on cattle numbers were collected. Descriptive epidemiology and time series data analyses were performed to detect seasonal trends. A total of 1,475 specimens were submitted for rabies testing. Of these, 1,248 (84.6%) were confirmed as rabies cases by immunofluorescence antibody testing. Domestic animals accounted for 73.8% (921/1,248) of all rabies cases, with cattle accounting for 61.1% (563/921) of domestic animal cases. Wildlife cases were reported principally in red foxes (56%; 183/327) and raccoon dogs (31.2%; 102/327). Time series analysis indicated a strong association between the occurrence of rabies in cattle and the season of the year (P = 0.0032), with the highest incidence of rabies occurring in autumn. The incidence declined from 3.4 to 4.8 cases per 100,000 cattle in the mid-1980s to < 1.5 cases per 100,000 cattle in 1994, but increased to 4.2 cases per 100,000 cattle in 1996. However, as the cattle population dramatically decreased (by 54%) over the eleven-year period of the study, the reduction in the total number of rabies cases in cattle was not reflected in the annual incidence rate of cattle rabies.

Animals↗
PubMed1998

Hoof size, shape, and balance as possible risk factors for catastrophic musculoskeletal injury of Thoroughbred racehorses.

OBJECTIVE: To evaluate hoof size, shape, and balance as risk factors for catastrophic musculoskeletal injuries (CMI), including suspensory apparatus failure (SAF) and cannon bone condylar fracture (CDY) in Thoroughbred racehorses. ANIMALS: 95 Thoroughbred racehorses that died between 1994 and 1996. PROCEDURE: 38 quantitative measures of hoof size, shape, and balance were obtained from orthogonal digital images of the hoof and were compared between case horses with forelimb CMI (70), SAF (43), and CDY (10) injuries and control horses whose death was unrelated to the musculoskeletal system (non-CMI, 25). Comparison of group means between cases and controls was done using ANOVA, and multivariable logistic regression was used to estimate odds ratios. RESULTS: Odds of CMI were 0.62 times lower for a 5mm increase in ground surface width difference and 0.49 times lower for a 100-mm2 increase in sole area difference. Odds of SAF were 6.75 times greater with a 10 degrees increase in toe-heel angle difference and 0.58 times lower with a 100-mm2 increase in sole area difference. Odds of CDY were 0.26 times lower with a 3 degrees increase in toe angle, 0.15 times lower with a 5-mm increase in lateral ground surface width, and 0.35 times lower with a 100-mm2 increase in sole area difference. CLINICAL RELEVANCE: Decreasing the difference between toe and heel angles should decrease risk of SAF for Thoroughbred racehorses and should be considered in addition to increasing toe angle alone to help prevent catastrophic injury. Trimming the hoof to perfect mediolateral symmetry may not be a sound approach to avoiding injury.

Animals↗
PubMed1997

Economic evaluation of risks to producers who use milk residue testing programs.

OBJECTIVE: To evaluate the decision to test for milk antimicrobial residues in milk from dairy cows treated with procaine penicillin G (PPG). DESIGN: Economic-decision analysis after stochastic simulation. SAMPLE POPULATION: 1,000 computer-simulated cows/model. PROCEDURE: Meta-analysis of the Food Animal Residue Avoidance Databank was used to generate PPG disappearance curves for cows given single PPG treatments, IM, of 6,600 U/kg (3,000 U/lb) of body weight or 26,400 U/kg (12,000 U/lb), and multiple treatments at 26,400 U/kg (12,000 U/lb), IM. These curves were entered into 1,000-replication stochastic pharmacokinetic models, generating population-level milk PPG profiles for each treatment group for each day after treatment, which were subjected to economic-decision analyses of feasibility of residue testing. The model was evaluated for changes in herd size, proportion of herd available for testing, milk production, test price, test sensitivity/specificity, and withdrawal periods. RESULTS: For both single-treatment groups, a 2-day withdrawal period avoided violative residues. However, nearly two thirds of the cows risked false identification for violative residues. For the multiple-treated group, nearly 40% had violative residues after a 5-day withdrawal period, and an additional 10 to 15% risked false identification for violative residues. Economic analysis yielded a decision against testing; mean cost was $2 (ie, 5% more than the mean cost of not testing). CLINICAL IMPLICATIONS: Complex dynamics of current milk residue tests discourage practitioners from recommending procedures to clients. In general, increases in herd size, milk production, proportion of a herd available for testing, or milk price will increase the value of testing. Increasing test sensitivity decreases its desirability to producers.

Animals↗
PubMed1997

Effects of antimicrobial treatment at the end of lactation on milk yield, somatic cell count, and incidence of clinical mastitis during the subsequent lactation in a dairy herd with a low prevalence of contagious mastitis.

OBJECTIVE: To determine whether treating cows with antimicrobials at the end of lactation would lower the incidence of clinical mastitis, improve milk production, and decrease somatic cell count (SCC) in the subsequent lactation. DESIGN: Randomized blind field trial. ANIMALS: 233 Holstein cows from a single herd. All cows were in lactation 2 or greater. PROCEDURE: Cows were randomly assigned to treatment groups. Treated cows were given procaine penicillin G and novobiocin by intramammary infusion. Control cows were not treated. Farm personnel recorded cases of clinical mastitis. Milk yield and SCC were recorded during the subsequent lactation. RESULTS: Treatment did not significantly reduce the incidence of clinical mastitis when data for all cows were grouped or when data were stratified by lactation groups (lactation 2 vs lactation > or = 3) or by last SCC (< or = 500,000 cells/ml vs > 500,000 cells/ml). Somatic cell counts (first, mean of first 5, maximum of first 5) for treated and control cows were similar, and proportions of treated and control cows with SCC > 500,000 cells/ml at least once were not significantly different. Treated cows produced 179 kg (394 lb) more milk during the first 17 weeks of lactation than did control cows. CLINICAL IMPLICATIONS: Treating cows with antimicrobials at the end of lactation increased 17-week milk production during the subsequent lactation and, at current milk prices, was financially preferable to not treating them.

Analysis of Variance↗
PubMed1997

Survivorship approaches to measuring and comparing cull rates for dairies.

A study was undertaken to develop the use of survivorship methods in characterizing the magnitude of culling and in testing for differences in culling among dairy herds. A prospective observational study was conducted on nine herds representing 19482 cows. The cull rate derived from survivorship data was estimated as the weighted slope of the cumulative proportion of cows remaining in a herd after first parturition, where cumulative proportion was computed using a cohort life-table with intervals of 1 month. Cull rates ranged from 9.0-13.8% per 12 months of age, compared with culling density rates of 22.2-39.7 culled per 100 cow-years. Comparison of ranks of density rates, weighted-slope rates and median ages at culling among the herds illustrated that the measures were not interchangeable. An advantage of a survivorship approach to measuring culling was illustrated by the use of the Cox proportional hazards model that tested for differences in cull rates among herds. Results suggested that variation in culling among herds during the first lactation, and particularly during the first part of the first lactation, may be an important consideration in future studies of optimal culling practices. In addition to being able to compare culling among herds, a survivorship approach to measuring culling provides an estimate of the rate of removal that is not biased by age, in contrast to currently used methods.

Age Factors↗
PubMed1997

Effect of different sampling techniques on odds ratio estimates using hospital-based cases and controls.

Potential biases introduced by the use of hospital admission records have rarely been discussed in the veterinary literature. Veterinary Medical Teaching Hospital (VMTH) patient records kept at the University of California, Davis (UCD) School of Veterinary Medicine provide a unique opportunity to perform in-depth analyses on the effect of different control selection (sampling) techniques on odds ratio (OR) estimates for disease risk factors in a retrospective case-control study. Horses with Corynebacterium pseudotuberculosis abscesses (134) and the (secondary) study base population (source for controls) were identified, and a 'gold standard' OR for each category of the factors admission type, age, breed and sex was derived. Example data were used to calculate sampling ratios (SRs), defined as the ratio between any sample proportion (of an arbitrary risk factor) and the study base proportion for this risk factor. Sampling ratios different from 1.0 introduced biases into the observed OR estimates, when compared with the 'gold standard' OR. Three randomized samples (simple random, stratified random, systematic sampling), one matched (on date of admission) and three different diagnosis samples ('colic', 'cuts and lacerations', 'fractures') were selected from the study base, and the SRs for all categories of the four factors were derived. The matched and two different disease samples ('colic' and 'fractures') had especially wide ranges of observed SRs (and large errors in the OR estimates), whereas simple random and systematic sampling had comparably narrow ranges (less biased OR estimates). For the three randomized sampling techniques under study, repeated sampling was used to derive SR distributions. The SRs were approximately normally distributed. Analysis of variance and covariance showed that simple random and systematic sampling provided SR distributions with means closest to 1.0 (expected value) and small standard deviations. The OR estimates obtained from records selected by these two sampling techniques therefore were least biased. The findings demonstrate the importance of selecting appropriate sampling techniques in addition to properly defining the study (base) population. Sampling design introduces uncertainty into the OR estimates. The direction of the bias, however, depends on the OR between factor and disease in the source population (the 'gold standard'), and on the direction and magnitude of the SR. When combining the results from single and repeated sampling we conclude that sampling design is most influential on the range of the observed SRs (single samples), on the absolute deviation of the SR from 1.0 (expressed as SR delta Mean) and on the SR standard deviation (SD) (repeated sampling).

Animals↗
PubMed1997

Prevalence of and associated risk factors for shedding Cryptosporidium parvum oocysts and Giardia cysts within feral pig populations in California.

Populations of feral pigs (Sus scrofa) may serve as an environmental reservoir of Cryptosporidium parvum oocysts and Giardia sp. cysts for source water. We conducted a cross-sectional study to determine the prevalence of and associated demographic and environmental risk factors for the shedding of C. parvum oocysts and Giardia sp. cysts. Feral pigs were either live-trapped or dispatched from 10 populations located along the coastal mountains of western California, and fecal samples were obtained for immunofluorescence detection of C. parvum oocysts and Giardia sp. cysts. We found that 12 (5.4%) and 17 (7.6%) of 221 feral pigs were shedding C. parvum oocysts and Giardia sp. cysts, respectively. The pig's sex and body condition and the presence of cattle were not associated with the probability of the shedding of C. parvum oocysts. However, younger pigs (< or = 8 months) and pigs from high-density populations (> 2.0 feral pigs/km2) were significantly more likely to shed oocysts compared to older pigs (> 8 months) and pigs from low-density populations (< or = 1.9 feral pigs/km2). In contrast, none of these demographic and environmental variables were associated with the probability of the shedding of Giardia sp. cysts among feral pigs. These results suggest that given the propensity for feral pigs to focus their activity in riparian areas, feral pigs may serve as a source of protozoal contamination for surface water.

Animals↗
PubMed1997

Testing to fulfill HACCP (Hazard Analysis Critical Control Points) requirements: principles and examples.

On-farm HACCP (hazard analysis critical control points) monitoring requires cost-effective, yet accurate and reproducible tests that can determine the status of cows, milk, and the dairy environment. Tests need to be field-validated, and their limitations need to be established so that appropriate screening strategies can be initiated and test results can be rationally interpreted. For infections and residues of low prevalence, tests or testing strategies that are highly specific help to minimize false-positive results and excessive costs to the dairy industry. The determination of the numbers of samples to be tested in HACCP monitoring programs depends on the specific purpose of the test and the likely prevalence of the agent or residue at the critical control point. The absence of positive samples from a herd test should not be interpreted as freedom from a particular agent or residue unless the entire herd has been tested with a test that is 100% sensitive. The current lack of field-validated tests for most of the chemical and infectious agents of concern makes it difficult to ensure that the stated goals of HACCP programs are consistently achieved.

Animals↗