Article Text

Download PDFPDF

Evaluating the evidence
Comparing survival times in cattle with a left displaced abomasum treated with roll-and-toggle correction or right pyloro-omentopexy
Free
  1. Lisa Morrow and
  2. Marnie Brennan
  1. School of Veterinary Medicine and Science, University of Nottingham, UK

Statistics from Altmetric.com

Bottom line

  • The evidence suggests that there is no difference in survival time between cattle with a left displaced abomasum (LDA) treated using the roll-and-toggle technique and those with an LDA treated using pyloro-omentopexy. Therefore, the choice of approach should be based on the surgeon’s/farmer’s preference and practice/farm management guidelines.

Clinical scenario

One of your clients, Mr Bradford, calls and states that he thinks he might have a cow with a left displaced abomasum (LDA). You visit the farm, perform an examination and congratulate Mr Bradford on his deduction.

Mr Bradford is keen for a correction to be performed as the cow is one of his best milkers and he would like to give her the best possible chance of survival. You have had experience performing both the roll-and-toggle technique and right pyloro-omentopexy, and you discuss the risks and benefits associated with these two approaches. Mr Bradford’s primary concern is how many more lactations the cow will have following the procedure. You wonder if there is any evidence of increased postoperative longevity with either approach.

The question

In [cattle with a left displaced abomasum] does [roll-and-toggle correction compared with right pyloro-omentopexy] affect [survival in the herd]?

Search parameters

The search strategy can be viewed at https://bestbetsforvets.org/bet/573, and is also available as a supplement to this article on Vet Record’s website at https://veterinaryrecord.bmj.com/content/187/5/192

Supplemental material

Search outcome

  • One hundred and sixty-six papers were found in the Medline search.

  • One hundred and sixty-one were excluded because they did not answer the question.

  • Three were excluded because they were review articles, in vitro research or conference proceedings.

  • In total, two relevant papers were obtained.

  • Five hundred and three papers were found in the CAB search.

  • Four hundred and ninety-six were excluded because they did not answer the question.

  • Four were excluded because they were review articles, in vitro research or conference proceedings.

  • One was excluded because it was not written in English.

  • In total, two relevant papers were obtained.

  • Overall, two relevant papers were identified.

Search last performed: 16 June 2020

Summary of evidence

Paper 1: Economic comparison of the pyloro-omentopexy vs the roll-and-toggle procedure for treatment of left displacement of the abomasum in dairy cattle1

Patient group: A total of 72 Holstein cows with an LDA that was corrected using either the roll-and-toggle procedure or pyloro-omentopexy were included in the study. All of the cows were from a single farm in the USA.

Study type: Randomised controlled trial.

Outcomes: Daily milk production was measured for 120 days after correction of the LDA and compared with that of cows unaffected by LDA. The value of milk production lost as a result of LDA was then calculated. The number of cows that died or were culled after surgery was also recorded. The estimated cost of cows removed from the herd and the value of lost milk production were combined to calculate the estimated total economic impact of LDA.

Key results: No statistical analysis was performed to compare livestock loss (ie, the number of cows that died or were culled) between the pyloro-omentopexy and roll-and-toggle groups. However, our own analysis of the data presented in the paper found no significant difference between the two groups.

Study weaknesses: Comparing survival in the herd between the two treatments for LDA – the outcome of interest for this evidence evaluation – was not a primary aim of the study. Survival in the herd is influenced by many factors that have not been measured or quantified in this study.

Cows from only one farm were included, and it is somewhat unclear how the cows were assigned to the three different surgeons that performed the LDA correction procedures. Referenced methods were not used for the measurement of all outcomes, and not all causes of death or reasons for culling are described.

There is a lack of basic data reported in the results, and null findings are not adequately interpreted in the discussion. Not all statistics used were described in the methods, so it is difficult to determine what type of analysis was carried out to obtain all of the results given.

Paper 2: Retrospective evaluation of milk production and culling risk following either surgical, toggle-pin suture or conservative treatment of left displaced abomasum in Chilean dairy cows2

Patient group: A total of 129 dairy cows, from four high-producing herds in Chile, that had been treated for an LDA between 2010 and 2012 were included in the study. The same number of unaffected control cows, matched by days in milk, parity and herd, were also included.

Study type: Retrospective cohort study.

Outcomes: The proportion of cows from each herd that were enrolled in the study and the proportion of these cows that were culled before 300 day in milk was calculated. The mean daily milk yield for each week (up to four weeks of lactation), the mean daily milk yield for each month (up to five months of lactation) and the total milk yield at 300 days in milk were recorded for each cow enrolled.

Key results: The proportion of cows in the unaffected control group that were culled was significantly less than in the groups treated for LDA (P=0.001). The risk of culling, corrected for parity and herd, was higher for the conservatively treated cows than for the cows treated using pyloro-omentopexy or the roll-and-toggle technique (P=0.03). However, the risk of culling, corrected for parity and herd, did not differ between the pyloro-omentopexy and roll-and-toggle groups (P=0.78).

Study weaknesses: Only four herds participated in the study, and the animals included were those operated on by one of the authors ‘when scheduling and availability permitted’. It is, therefore, possible that not all animals with an LDA in these herds were included.

The roll-and-toggle procedure was performed by farm staff and the pyloro-omentopexy was carried out by a vet. Cases were not randomly allocated to treatment groups as the choice of treatment was dependent on vet availability and management choice. This could have introduced bias into the treatment group allocations. It is unknown whether the animals had more than one treatment option attempted.

No information is provided regarding how the decision to cull was made. Other factors that may influence culling risk, such as mastitis, ketosis, milk fever, endometritis, history of previous LDA and management choice, are not considered in this study.

As the main purpose of the study was to compare cows with LDA with healthy herd mates, there is limited analysis comparing the roll-and-toggle technique with pyloro-omentopexy. Direct comparison is further complicated due to the comparatively small number of animals in the roll-and-toggle group.

Variation in disease severity and/or time of diagnosis in relation to onset of disease between the treatment groups could confound the results obtained. However, the latter is unlikely as the study reports high levels of postpartum health checks and similar cow management between herds. Additionally, it is not common practice in all countries for farm staff to perform the roll-and-toggle procedure, and this may affect the extent to which the results can be generalised.

Comments

There appears to be no difference in survival time between cattle treated for LDA using the roll-and-toggle technique and those treated using pyloro-omentopexy. However, survival in the herd is determined by multiple factors associated with the individual cow as well as herd management factors. Therefore, farmers and vets will also need to consider these factors when making decisions on treatment options for LDA.

The ‘Evaluating The Evidence’ section of Vet Record aims to answer specific clinical questions using a systematic approach to identify and succinctly summarise the relevant evidence from the scientific literature. The shortcomings of this evidence are also taken into account, thereby enabling vets to incorporate the best available evidence from the literature when making clinical decisions. Please contact us at vet.research@bmj.com if you have an article you would like us to consider for publication in this section.

References

View Abstract

Request Permissions

If you wish to reuse any or all of this article please use the link below which will take you to the Copyright Clearance Center’s RightsLink service. You will be able to get a quick price and instant permission to reuse the content in many different ways.