Exploration of the potential utility of the luciferase immunoprecipitation system (LIPS) assay for the detection of anti-leptospira antibodies in dogs

Canine leptospirosis represents a diagnostic challenge to veterinarians, due to the variability in presenting clinical signs and interpretation of serology test results in dogs that have been vaccinated previously. None of the commercially available serological assays, including the microscopic agglutination test (MAT), have been verified to be capable of differentiating infected from vaccinated animals (DIVA). Recent work identified that half of primary practice attending dogs were up to date with their leptospirosis vaccination and would be expected to have circulating anti-leptospira antibodies (Taylor et al., 2022), indicating that this is a relevant issue for suspected leptospirosis cases in dogs in the UK. This study aimed to explore the utility of three leptospiral outer membrane proteins (OMPs: LipL32, LipL21 and LipL41) as potential DIVA targets in the luciferase immunoprecipitation system (LIPS) assay. N and C terminal nanoluciferase tagged recombinant proteins were generated for each OMP. Differences in reactivity between serum samples from MAT positive dogs (n = 29) and paired samples (n = 6 dogs) taken pre and 21 days post leptospirosis vaccination were assessed against these six constructs. Reactivity was greater towards the N terminal than the C terminal recombinant proteins for all three OMPs. None of the constructs appeared to demonstrate DIVA capability, although two (pNLF1-N-FLAG/LipL32 and pNLF1-N-FLAG/LipL21) were able to detect vaccine seroconversion. The findings of this work suggest that these particular OMP targets do not offer DIVA ability, however LipL32 and LipL21 may be suitable for use in immunoassays for vaccine trials or for detection of infections in humans, where there is no requirement for DIVA capability.

Epidemiology and risk factors for mammary tumours in female cats

OBJECTIVES

This study aimed to estimate the incidence and risk factors for mammary tumours in female cats attending UK primary-care practices. The study hypothesised that middle-aged, intact and certain breeds are associated with increased mammary tumour risk.

MATERIALS AND METHODS

A case-control study design identified mammary tumour cases by assessment of electronic patient records, nested within a denominator population of 259,869 female cats attending 886 primary-care VetCompass participating veterinary practices in the UK in 2016.

RESULTS

From 2858 potential mammary tumour cases identified within the denominator, 270 cats met the case definition, giving an incidence risk of 104 per 100,000 (0.104%, 95% confidence interval 0.092 to 0.117%) during 2016. In the risk factor analysis increasing age, purebred compared to crossbred and veterinary group were associated with increased odds of mammary tumour. Median survival after the diagnosis of mammary tumour cats was 18.7 months.

CLINICAL SIGNIFICANCE

The current study provides an updated estimate of the incidence of mammary cancer in cats seen in primary care veterinary practice in the UK with increasing risk seen in older cats and with purebred status. This study can aid veterinary surgeons to identify cats at greater risk of mammary tumour and advise on survival after diagnosis.

Antimicrobial usage in farm animal practices in the UK: A mixed-methods approach

Antimicrobial resistance (AMR) is a growing One Health problem. Monitoring antimicrobial usage in farm animals is crucial for tackling AMR. A cohort study using the electronic clinical records during 2019 from 23 farm animal veterinary practices across the UK belonging to two corporate groups, with a range of 2-14 veterinarians per practice, estimated the usage of antimicrobials and highest priority critically important antimicrobials (HP-CIAs). Risk factors for using HP-CIAs were evaluated using hierarchical mixed-effects logistic regression modelling with practice ID and farm ID added as random effects. Using a qualitative approach, veterinarians from one of the participating practice groups were recruited for a qualitative study to explore the barriers and facilitators in relation to antimicrobial use. Semi-structured interviews were conducted with participants and analysed thematically. During the year 2019, 98,824 antimicrobial prescribing events overall were recorded from the treatment records of the 23 participating practices. The median count of antimicrobial events per practice was 3226 (range 263-22,159). There were 17,111/98,824 (17.3%) HP-CIAs events overall, with a median of 15.4% at practice level (range 4.8-22.1%). Penicillins were the most frequently used antimicrobials 29,539/98,824 (29.9%) followed by tetracyclines 19,015/98,824 (19.2%). HP-CIA use was strongly clustered, with more clustering seen at the farm level (intraclass correlation coefficient (ICC)= 0.56) than at the practice level (ICC= 0.32). Country, route of administration, season and practice type were significantly associated with the usage of HP-CIAs. Four main themes were identified from the analysis of the veterinarians' interviews: pressure from the industry, drug-related factors, knowledge level of veterinarians and clinical factors. Supermarket contracts and farm assurance schemes were facilitators for reducing antimicrobial use and the use of HP-CIAs. Ease of administration and the withdrawal period of the antimicrobials influenced veterinarians' choice of antimicrobials. The clinical condition and clinical signs presented on farm were reported to influence participating veterinarians' prescribing decision. Participants showed a good understanding of AMR, responsible use of antimicrobials and the term 'critically important antimicrobials'. In conclusion, integrating the quantitative and qualitative findings can inform policymaking on antimicrobials stewardship in farm practice. By estimating the relative levels of clustering of antimicrobial use at the practice and farm level, as well as identifying major risk factors for using HP-CIAs, more targeted interventions can be designed to promote responsible antimicrobial use in farm practice. Furthermore, better understanding the industry pressures on farms to reduce antimicrobials usage could reduce the barriers for responsible antimicrobial use by veterinarians.

Incidence and risk factors for feline lymphoma in UK primary-care practice

Objectives

The study aimed to estimate the incidence and prevalence of feline lymphoma in cats attending primary‐care practices across the UK and to identify patient‐based and environmental (radon and pesticide exposure) risk factors.

Materials and Methods

Case records from the VetCompass programme from primary‐care veterinary practices in the UK were searched for a diagnosis of lymphoma in cats in 2016. Cases were required to have had an external laboratory confirmed diagnosis based on cytology and/or histopathology. A nested case–control study design was used to identify risk factors for lymphoma using multivariable logistic regression.

Results

From a cohort of 562,446 cats under veterinary care at VetCompass participating practices in 2016, a total of 271 lymphoma cases were identified (prevalence: 48/100,000, 95% confidence interval (CI) 44 to 56/100,000; incidence 32/100,000, 95% CI 26 to 35/100,000). There were 180 incident lymphoma cases and 803 controls, all aged 2 years and older. Male (odds ratio (OR) 1.7, 95% CI 1.2 to 2.4), insured (OR 3.6, 95% CI 2.3 to 5.6) and older cats (compared to cats 2 to <5 years, OR 5.0, 95% CI 2.8 to 8.8) were associated with increased odds of lymphoma diagnosis. Vaccinated cats were associated with decreased odds (OR 0.7, 95% CI 0.5 to 1.0) compared to unvaccinated cats, although the type of vaccination received was not statistically significant. Breed and environmental factors studied were not associated with a diagnosis of lymphoma.

Clinical Significance

This is the first study to estimate the frequency and report risk factors for lymphoma in cats attending UK primary‐care practice.

Epidemiology of road traffic accidents in cats attending emergency-care practices in the UK

OBJECTIVES

To estimate the incidence proportion of road traffic accidents in cats attending emergency out-of-hours clinics in the UK, identify major risk factors for road traffic accident occurrence and for survival to discharge.

MATERIALS AND METHODS

A retrospective study of a cohort of 33,053 cats in the VetCompass database attending emergency-care practice between January 1, 2012 and February 15, 2014. Incidence proportion was calculated and logistic regression was used to identify risk factors for road traffic accident and survival to discharge following road traffic accident.

RESULTS

Incidence proportion was estimated at 4∙2% (95% confidence interval: 4∙0 to 4∙4%). Cats aged 6 months to 2 years were at increased odds of road traffic accident, as were male cats and crossbred cats. Odds of road traffic accident were highest in the autumn. Spinal injury, abdominal injury and increasing count of injuries were associated with increased odds of death.

CLINICAL SIGNIFICANCE

Road traffic accident is a frequent presentation in emergency-care practice. Identification of risk factors for death within the first 24 hours following a road traffic accident can aid veterinarian and owner decision-making for treatment of cats involved in a road traffic accident.

Characterisation of antimicrobial usage in cats and dogs attending UK primary care companion animal veterinary practices

There is scant evidence describing antimicrobial (AM) usage in companion animal primary care veterinary practices in the UK. The use of AMs in dogs and cats was quantified using data extracted from 374 veterinary practices participating in VetCompass. The frequency and quantity of systemic antibiotic usage was described.Overall, 25 per cent of 963,463 dogs and 21 per cent of 594,812 cats seen at veterinary practices received at least one AM over a two-year period (2012-2014) and 42 per cent of these animals were given repeated AMs. The main agents used were aminopenicillin types and cephalosporins. Of the AM events, 60 per cent in dogs and 81 per cent in cats were AMs classified as critically important (CIAs) to human health by the World Health Organisation. CIAs of highest importance (fluoroquinolones, macrolides, third-generation cephalosporins) accounted for just over 6 per cent and 34 per cent of AMs in dogs and cats, respectively. The total quantity of AMs used within the study population was estimated to be 1473 kg for dogs and 58 kg for cats.This study has identified a high frequency of AM usage in companion animal practice and for certain agents classified as of critical importance in human medicine. The study highlights the usefulness of veterinary practice electronic health records for studying AM usage.

Population characteristics and survival in 127 referred cats with hypertrophic cardiomyopathy (1997 to 2005)

OBJECTIVES

To evaluate the characteristics and survival of a recent population of cats with hypertrophic cardiomyopathy.

METHODS

Records at the Royal Veterinary College Queen Mother Hospital for Animals were searched for cats diagnosed with hypertrophic cardiomyopathy between 1997 and 2005. Referring veterinarians and owners were contacted to determine survival times.

RESULTS

Cats with hypertrophic cardiomyopathy were evaluated for population characteristics (n=127) and survival times (n=109). Overall median survival from date of hypertrophic cardiomyopathy diagnosis at the Queen Mother Hospital for Animals was 1276 days. Cats with hypertrophic cardiomyopathy were younger (P=0·009), and more likely to be male (P<0·001) compared to a hospital control group (n=1473), and Ragdolls were over-represented (P<0·05). Characteristics associated with increased survival in univariate analysis included younger age (P=0·007), asymptomatic status (P<0·001), normal left atrial size (P<0·001) and presence of systolic anterior motion of the mitral valve (P=0·003). Systolic anterior motion was associated with asymptomatic status, and did not influence survival in asymptomatic cats or those in congestive heart failure. Age, left atrial size and breed were significantly associated with survival time in a multivariate analysis.

CLINICAL SIGNIFICANCE

Cats with hypertrophic cardiomyopathy and left atrial enlargement have a poorer prognosis. The positive influence of systolic anterior motion on survival is likely to be linked to its association with asymptomatic status.

Evaluation of surface contamination with staphylococci in a veterinary hospital using a quantitative microbiological method

OBJECTIVES

To evaluate microbial contamination of the environment in a veterinary hospital using standards recommended for human hospitals and to provide a baseline against which further investigations can be compared.

METHODS

Surfaces were sampled twice daily for five consecutive days using a contact-based counting method to measure the levels of staphylococci in colony forming units (cfu) per cm².

RESULTS

Current recommendations for human hospitals were applied in this study; all samples with <2.5 cfu/cm² staphylococci were considered to have passed and those with ≥2.5 cfu/cm² to have failed. Of all the samples, 55.9% failed. The ICU did not have significantly higher failure rates than other areas of the hospital. The floor as a surface was associated with greater than a threefold increase in odds of elevated cfu concentrations relative to the door handle.

CLINICAL SIGNIFICANCE

This study provides information on the microbiological cleanliness of a veterinary teaching hospital using techniques and standards adopted by the food industry and recommended for human hospitals. This data can be used as a baseline for other hospitals, to evaluate the effectiveness in improvements in hygiene and cleaning measures and to design effective hospital cleaning protocols and assess ongoing hygiene standards.

Risk factors for tail injuries in dogs in Great Britain

The aim of the current study was to quantify the risk of tail injury, to evaluate the extent to which tail docking reduces this risk, and to identify other major risk factors for tail injury in dogs in Great Britain. A nested case-control study was conducted during 2008 and 2009. Data were obtained from a stratified random sample of veterinary practices throughout Great Britain, and questionnaires were sent to owners of dogs with tail injuries and owners of a randomly selected sample of dogs without tail injuries. The risks of injury were reported adjusting for the sampling approach, and mixed effects logistic regression was used to develop a multivariable model for risk factors associated with tail injury. Two hundred and eighty-one tail injuries were recorded from a population of 138,212 dogs attending 52 participating practices. The weighted risk of tail injuries was 0.23 per cent (95 per cent confidence interval 0.20 to 0.25 per cent). Thirty-six per cent of injuries were reportedly related to injuries sustained in the home, 17.5 per cent were outdoor-related injuries, 14.4 per cent were due to the tail being caught in a door, for 16.5 per cent the cause was unknown and the remainder were due to other causes. Dogs with a wide angle of wag and dogs kept in kennels were at significantly higher risk of sustaining a tail injury. Dogs with docked tails were significantly less likely to sustain a tail injury; however, approximately 500 dogs would need to be docked in order to prevent one tail injury. English springer spaniels, cocker spaniels, greyhounds, lurchers and whippets were all at significantly higher risk when compared to labradors and other retrievers. Differences between countries (England, Scotland and Wales) and between rural and urban environments were not significant.

Survey of veterinary practice policies and opinions on neutering dogs

A cross-sectional survey was conducted in 2008 to obtain information on the advice veterinary practices currently give to their clients and the opinions of veterinary surgeons regarding neutering of dogs. An additional survey of dog owners was conducted to obtain information on the neuter status of the general dog population in Great Britain. A significantly higher proportion of practices had a policy for the age of neutering bitches than for dogs. The average recommended age for neutering bitches was 6.5 months (95 per cent confidence interval [CI] 3.1 to 9.7 months) and for dogs it was 7.5 months (95 per cent CI 1.4 to 13.6 months). There was very little agreement between veterinary practices as to whether bitches should be allowed to have their first season before neutering, with 164 of 973 respondents (16.9 per cent) always recommending this, 198 (20.3 per cent) recommending it most of the time, 203 (20.9 per cent) sometimes, 203 (20.9 per cent) rarely and 201 (20.6 per cent) never recommending it. The owner study showed that 54 per cent of dogs (233 of 431) were neutered, with the North region having the lowest proportion of neutered dogs (11 of 25; 44.0 per cent).

Prospective evaluation of complications associated with jugular venous catheter use in a veterinary hospital

OBJECTIVES

To prospectively investigate the incidence of mechanical and infectious complications associated with the use of jugular catheters and risk factors for these complications.

METHODS

Data was collected over a 6-month period and risk factors associated with the occurrence of mechanical or inflammatory complications were investigated.

RESULTS

One hundred catheters were placed over a 6-month period, totalling 393 catheter days. Complications were seen in 39% of catheters with a total of 51 complications. Forty-one of these complications were mechanical. A total of 10 inflammatory or infectious complications were identified in eight catheters (a total of 0.03 infectious complications per catheter day). Complications were more likely to occur in patients requiring more than one attempt for placement and patients that were ASA status 3 to 5. Infectious complications were more likely in patients not having general anaesthesia for placement, those having medical rather than surgical disease and those placed out of theatre. No association was found between the skill of the person placing the catheter and risk of complication.

CLINICAL SIGNIFICANCE

Mechanical complications are frequently associated with jugular catheter placement. Identification of risk factors for complications is important and warrants further study.

N-terminal pro B-type natriuretic peptide and left ventricular diameter independently predict mortality in dogs with mitral valve disease

OBJECTIVES

To determine whether natriuretic peptide concentrations would predict all cause mortality in dogs with degenerative mitral valve disease.

METHODS

One hundred dogs with naturally occurring degenerative mitral valve disease were prospectively recruited for this longitudinal study. Analysis of outcome was undertaken for 73 dogs for which the outcome was known. Dogs underwent physical examination, electrocardiography and echocardiography. Natriuretic peptide concentrations were measured by Enzyme-linked immunosorbent assay. The ability of natriuretic peptide concentrations, clinical, electrocardiographic and echocardiographic data, to predict all cause mortality was determined using univariable and multivariable Cox proportional hazards analyses.

RESULTS

Thirty dogs died during the period of follow-up. Two variables were independently predictive of all cause mortality; these were the normalised left ventricular end-diastolic diameter and the N-terminal pro B-type natriuretic peptide concentration. An increase of the left ventricular end-diastolic diameter by 0.1 increased the hazard of all cause mortality by 20% (95% confidence interval: 4 to 37%, P=0.01) and a 100 pmol/l increase in N-terminal pro B-type natriuretic peptide increased the hazard by 7% (95 confidence interval: 2 to 11%, P=0.003).

CLINICAL SIGNIFICANCE

N-terminal pro B-type natriuretic peptide concentration and left ventricular end-diastolic diameter are significantly and independently predictive of all cause mortality in dogs with degenerative mitral valve disease.

Plasma lactate concentrations and blood gas values in dogs undergoing surgical attenuation of a single congenital portosystemic shunt

Plasma concentration of lactate and the values of pH, pO(2) and pCO(2) were measured in the portal, systemic venous and, when possible, systemic arterial blood of 31 dogs with a single congenital portosystemic shunt, before and shortly after the temporary complete occlusion of the shunt, and at the end of surgery. At completion of the surgery, the shunt in 16 of the dogs had been occluded completely whereas in the other 15 it had been occluded only partially. There were no significant differences between any of the measurements of these variables in the portal venous, systemic venous or arterial plasma of any of the dogs, or between the values measured in the groups in which the shunts had been occluded completely or partially. Furthermore, there were no significant differences between the two groups of dogs in the arteriovenous gradients calculated at any of the sampling sites or sampling times. None of the variables was associated with the development of postoperative complications.

Evaluation of predictors of the development of azotemia in cats

BACKGROUND

Chronic kidney disease (CKD) is a common condition in geriatric cats. Diagnosis is based on the development of persistent azotemia with inadequate urine concentrating ability. Biomarkers are sought for early identification.

HYPOTHESIS

Clinical variables, urine concentrating ability, proteinuria, and N-acetyl-beta-D-glucosaminidase (NAG) index will be predictive of cats at risk of developing azotemia within 12 months.

ANIMALS

Client-owned nonazotemic geriatric (>or=9 years) cats.

METHODS

Prospective longitudinal cohort study monitoring a population of healthy nonazotemic geriatric cats every 6 months until development of azotemia, death, or the study end point (September 30, 2007). Multivariable logistic regression analysis was used to assess baseline clinical, biochemical, and urinalysis variables, urine protein to creatinine ratio (UP/C), urine albumin to creatinine (UA/C) ratio, and urinary NAG index as predictors of development of azotemia.

RESULTS

One hundred and eighteen cats were recruited with a median age of 13 years. Ninety-five cats (80.5%) had been followed or reached the study end point by 12 months of which 30.5% (29/95) developed azotemia. Age, systolic blood pressure, plasma creatinine concentration, urine specific gravity, UP/C, UA/C, and NAG index were significantly associated with development of azotemia in the univariable analysis (P<or=.05). However, in the multivariable analysis, only plasma creatinine concentration with either UP/C (Model 1) or UA/C (Model 2) remained significant.

CONCLUSIONS AND CLINICAL IMPORTANCE

This study demonstrates a high incidence of azotemia in a population of previously healthy geriatric cats. Proteinuria at presentation was significantly associated with development of azotemia although causal association cannot be inferred. Evaluation of NAG index offered no additional benefit.