Professor Ed Hall, our Breed Health Co- ordinator, attended the recent Large and Giant Breed Working Group meeting and one of the speakers was Professor Mark Dunning who gave a presentation on bloat. He is working with The Deerhound Club investigating the factors influencing bloating and the development and outcome of GDV in Deerhounds in the UK. Below are the minutes concerning his presentation and reproduced with kind permission from the Kennel Club.
Gastric Dilatation Volvulus (GDV)/ Bloat in Large and Giant Breeds
Prof Dunning gave a presentation to the group regarding current knowledge surrounding GDV.
He began by differentiating bloat and GDV, explaining that GDV, an acute life-threatening disease, results from serious bloat (or GD). The mechanisms of GDV were described, with the stomach turning on to its left side, which results in the oesophagus becoming twisted, preventing any air escaping out of the stomach and escalating the bloating. This causes extreme stretching of the tissues and displacement of the spleen and other organs. The following YouTube video was shared to show the movement: Patterson Veterinary DIA Client Education Video- Gastric Dilatation-Volvulus (GDV)- Bloat – YouTube
Torsion is incredibly serious as the movement of the stomach causes a stretching of the gastric wall, which prevents blood circulation and oxygen reaching tissues properly, leading to necrosis (cell death), clots, haemorrhage and possible peritonitis/ septicaemia. This leads to a wider obstruction of blood flow across the body of an affected individual, causing an elevated heart rhythm, whole-body inflammation and poorer chance of survival.
There is no simple solution for every dog but there are multiple factors that lead to an outcome, and therefore by understanding the general indicators we can better mediate and treat affected individuals. Risk factors include both intrinsic (within the body) and extrinsic (i.e. environmental) factors. Extrinsic factors include diet, frequency of feeding, type of food, elevated/ low-level feeding, exercise, history of or ongoing chronic gastrointestinal disease, and aerophagia (gulping air). Intrinsic factors are more difficult to change as they are inherent to the individual, these factors include the following: breed, the genetics of the immune system (i.e. whether it takes form in an autoimmune state and begins attacking tissues/ organs within the body, such as within the gut), body size, being deep-chested, gastric volume and position, how laxly the stomach is attached to the abdomen, being able to release gas, familial history of GDV, and temperament and stress.
MD noted that as such GDV is incredibly complex, and cannot be avoided by merely reducing one factor, but by reducing the risk of all the above where possible it is more likely to minimise overall risk.
With respect to research, MD noted there is a trend investigating the gut microbiome (bacteria populations) in affected dogs and underlying genetic components, pointing towards difficult inherent factors. There have been certain differences in gut microbiome found between GDV affected and unaffected dogs in recent years, which are being more easily identified thanks to advancements in technology and analysis. Future research and establishing the association between gastrointestinal flair-ups with GDV could allow for better prophylactic (preventative) treatments. The importance of educating owners in normalising abnormal underlying disease (e.g. ongoing loose stools) was also highlighted as being important due to the established links between such disease and GDV risk. This research indicates an element of immune dysfunction and that further genetic research is necessary to establish whether any genes that maintain the immune system also influence GDV. Several recent papers have begun to identify a number of genes associated with GDV affected dogs.
A limitation of research is that many breeds affected have very numerically small populations, and therefore the disease has not been well described in some of these breeds. With this, much of MD’s research is to work with the breeds and BHCs to access these data, which would otherwise be lost through veterinary practice/ hospital datasets.
MD then gave an overview on outcomes in affected dogs and how mortality rates have changed overtime post-surgery. Certain procedures will alter the likelihood of outcome, with removal of organs (i.e. parts of the stomach/ spleen) further increasing the risk of mortality. Outside of surgery other factors that can impact prognosis include, how quickly a dog is presented to the vets, and whether the dog is showing signs of critical inflammation/ hypotension/ sepsis/ peritonitis/ necrosis and splenic trauma. A further factor identified has been arrhythmia which can lead to an increased risk of mortality. Echocardiogram is needed to identify any dangerous or unstable arrhythmias, particularly any abnormalities where the heart is attempting to contract during its relaxed phase – these arrhythmias will require intervention to prevent fatality.
Sadly, MD reported that studies have found 50% of dogs presented with GDV are euthanised on arrival, without undergoing any further treatment. There are a number of factors which lead towards this, primarily being cost and/ or being uninsured, and time of day (i.e. cases presented overnight are less likely to survived). Longer surgeries have also been suggested to negatively influence a dog’s likelihood of survival, however MD did note that there will be variability in a surgeon’s/ support team’s skills which makes data difficult to interpret.
Biomarkers available that help predict a dog’s outcome post-surgery include CRP, lactate, cPLI, and procalcitonin which give indication for the amount of inflammation and circulatory distress occurring in the body. Having the ability to measure these will allow the vet team to further assess a dog’s clinical status and gives strategic measurements, which can be taken into account for a dog’s recovery, and give a better prediction of a dog’s likelihood to survive.
MD then walked the group through the process from development of symptoms to presentation at veterinary level. Diagnosis is needed to differentiate between bloating and GDV. Primary clinical signs included non-productive and continuous retching/ vomiting, a progressive abdominal swelling, pain, depression, pacing, and being in shock. MD noted that having even a small inkling of something being wrong is enough to warrant taking a dog to the vet, as it has been proven that early action is key to survival.
Surgeons on presentation will be looking to restore circulation and oxygen to tissues, decompressing the stomach via a stomach tube, determining whether the disease is GD or GDV through imaging (X-ray or CT scan), surgical correction if needed, and further prophylaxis to prevent any future episodes. If lavage via a stomach tube is not effective, letting the air out through a needle in the abdomen is also an effective method. During surgery a surgeon will untwist the stomach, then look at whether any stomach/ spleen tissue needs removing, and then fix the stomach via gastropexy to prevent any further GDV episodes.
Prophylactic gastropexy is becoming more widely used and can be undertaken at the time of neutering as part of a routine procedure. MD did note that incisional gastropexies appear to be less effective than other prophylactic gastropexies, however further work is needed here to tease apart efficacy. MD did go on to note that any form of pexy is going to give a better chance than no prophylaxis. Studies that have monitored dogs that have had appropriate gastropexies have found that none of these have gone on to develop GDV. It was noted that gastropexy should not be undertaken on dogs that have not yet reached maturity.
MD went on to discuss ‘low-hanging fruit’ (e.g. epidemiology) and complex investigations (e.g. genetics) research and management, and that both of these approaches should be made in tandem to manage disease risk. It was noted that as this is not a simple genetic disorder and cannot be selected against to be completely eradicated, but can be taken into account to produce less-predisposed progeny, and continuing to manage extrinsic factors will help to minimise risk.
MD’s research suggest that different breeds have different factors contributing towards disease risk; for example for Deerhounds a recent stressful event has been thought to contribute more heavily to disease, in comparison to Greyhounds where having a history of abdominal surgery contributes further. Identifying such subtle signs and pointers will allow owners to manage their animals with this in mind, and determine whether and how quickly they need to get their dog to the vets. MD’s student is working on analysis for a number of other breeds, where it is hoped that other findings can be established.
The importance of improving communications between owners, breeders and vets was stressed, to allow a more complimentary approach to breed care. As such, MD was keen to work with the BHCs to improve breed-specific understanding. Any breeds that would like to collaborate with MD’s project should email Hannah who will put them in touch with MD’s team. Many breeds have worked on their own surveys which have been very useful in gauging prevalence and identifying initial factors involved in their breed’s risk, however it was mentioned that to allow a consistent and universal approach it would be beneficial to make use of MD’s team and resourcing to further expand on this work.
The floor was then opened up to the breed representatives for any questions or comments.
A query was raised with respect to raised feeding, with MD noting that the picture is mixed, and should be tailored to an individual dog. The most important factor to consider is whether a dog is aerophagic or not therefore owners should observe whether the dog gulps food. To manage this factor owners should aim to slow down rate of feeding and evaluate whether raised/ low-level feeding improves this.
The picture surrounding diet is still complex, but increasing the amount of time that the body takes to digest food is thought to have an impact. The group queried what the current knowledge is in respect to raw versus kibble and risk. MD noted that raw is a difficult factor to pick apart as there are a number of different forms of raw, alike to kibble. At this stage anecdotally dogs that move onto raw have less gastrointestinal disease, however long-term studies are needed to follow dogs overtime to try to identify influence. Underlying intestinal health certainly appears to have an influence on development of GDV, but further work is needed in this area. There are also subtleties in diet, with many dogs fed extra supplements/ bits of raw, kibble etc. so obtaining a study group with set and consistent feeding patterns will be a difficult objective to meet.
“Simple” genetic gene tests have been said to be available, however the efficacy of these have not been published in the peer-reviewed literature, and given that the condition is thought to be a complex disease with multiple interplaying genes, it is unlikely that these tests are, at present, good predictors of disease.
Many of the BHCs reported in their own experience that stress had seemed to be a contributing factor, and the importance of knowing your own animal and improving understanding owner awareness and husbandry.
The group thanked MD for his time and willingness to join the group to share his experience.