26 Aug 2019
In his latest Research Review column for Veterinary Times, Alex Gough presents more research from the veterinary field.
Alex Gough
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Image: © sonsedskaya / Adobe Stock
Oesophageal feeding tubes are a relatively straightforward way of placing a tube to allow enteral nutrition in cats. However, potential complications are associated with the procedure to put the tube in place.
Breheny et al1 performed a retrospective case review of clinical records at two referral centres to look for data on signalment, indication for placement, method of placement, time of removal and complications. A total of 248 cases were identified and included in the study.
For cats that survived to discharge, the tubes were kept in place for a median duration of 11 days. However, the range was up to 93 days. In total, 36% of cats experienced complications, including dislodgement of the tube and infection of the stoma site.
Cats receiving glucocorticoids or chemotherapy had an increased risk of stoma site infection. A lower weight – or pancreatic, neoplastic, urogenital, respiratory and infectious diseases – increased the odds of death.
The authors suggested the risks of oesophageal tube placement need to be discussed with owners prior to the procedure.
Restrictive cardiomyopathy is one of the cardiomyopathies seen in cats and may predispose to an increased risk of aortic thromboembolism, as it is often associated with markedly enlarged atria.
Chetboul et al2 performed a retrospective study of 92 cats with restrictive cardiomyopathy to describe clinical, epidemiological, echocardiographic and prognostic features of the disease. In total, 90% of cats had the myocardial form of the condition, while 10% had the endomyocardial fibrosis form. A total of 70% of cases were showing clinical signs at the time of diagnosis, and of these, 89% were showing dyspnoea due to congestive heart failure.
The median survival time for cats with the myocardial form was 667 days. Severe left atrial enlargement was associated with a shorter time until cardiac death.
The authors concluded cardiac death is common in cats with restrictive cardiomyopathy, and the size of the left atrium appears to be independently associated with decreased survival time.
The Ehmer sling is a bandaging technique commonly used after closed reduction of craniodorsal hip luxation. It holds the leg in flexion with the hip in abduction and internal rotation.
Schlag et al3 performed a retrospective multicentre cohort study of 92 dogs that had Ehmer slings placed after closed reduction of hip luxation. In total, 44% of the dogs suffered a reluxation around the time of removal of the sling. Dogs with a known trauma as the cause of the luxation were five times more likely to reluxate than those without known trauma.
A total of 46 dogs (50%) suffered soft tissue injuries caused by the use of the sling; 17 of these dogs had severe injuries and 1 required amputation. The odds of a severe sling injury were greatly increased where poor owner compliance with home care instructions existed, where the sling was placed by an intern or resident rather than a board-certified surgeon, and where the sling was noted to be wet or soiled on at least one occasion.
The authors concluded the use of an Ehmer sling after closed reduction of hip luxation has a low success rate and a high complication rate.
Cannabidiol (CBD) is one of the cannabinoids found in cannabis plants. It has been reported to improve seizure control in children with rare and severe epilepsy syndromes.
McGrath et al4 performed a randomised, blinded, controlled clinical trial of 26 dogs with intractable idiopathic epilepsy. The dogs were randomly assigned to receive CBD or placebo for 12 weeks, in addition to their existing antiepileptic drug treatments.
In total, 2 dogs that received CBD were withdrawn from the study after experiencing ataxia, and 9 dogs in the CBD group and 7 in the placebo trial were included in the study analysis.
Dogs in the CBD group experienced a significant reduction in seizure frequency, with a median change of 33%. However, to be considered a responder, a 50% decrease in seizures was required, and no significant difference existed in the numbers classified as responders between the groups. A correlation existed between plasma CBD concentration and the reduction in seizure frequency. Alkaline phosphatase levels increased in the CBD group.
The authors concluded more research is needed to ascertain whether a higher CBD dose might improve seizure control further.
Risk factors associated with lifespan are of great interest to vets and pet owners to adjust lifestyle and other recommendations to maximise longevity.
Urfer et al5 performed a population-based retrospective cohort study to identify risk factors associated with lifespan in pet dogs attending 1 of 787 primary care veterinary practices in the US.
Dogs of at least three months of age visiting a hospital at least twice in 2010-12 were included in the study. Reproductive status, breed, body size and pure-breed versus mixed-breed status were assessed. More than two million dogs were included in the study, and 7.6% died during the study period.
Mixed-breed dogs were found to live significantly longer than pure-breed dogs, and a greater difference was noted with increasing body size. Being neutered reduced hazard of death in both sexes when other factors were controlled for. Hazard of death reduced with increased frequency of dental prophylaxis.
The authors concluded this study supports previous evidence that suggests an impact on longevity for body size and neutering, and provides new evidence that mixed-breed dogs and dogs experiencing regular ultrasonic dental scaling had an increased lifespan.
Non-traumatic haemoabdomen is an emergency presentation that can have a number of causes. Schick et al6 performed a retrospective, multicentre, observational cohort study of 406 dogs presenting with non-traumatic haemoabdomen to calculate a risk prediction model for haemangiosarcoma (HSA) diagnosis. All dogs included in the study had a histological diagnosis from surgical exploration or postmortem examination.
A risk score was calculated from bodyweight, total plasma protein, platelet count and thoracic radiography. HSA incidence was 36% in those with a low risk score, 76% in those with a medium risk score and 96% with a high risk score.
The authors concluded a simple risk score was useful in predicting the risk of HSA, and this could aid in the diagnostic and treatment decisions for dogs presenting with non-traumatic haemoabdomen.
Hip dysplasia (HD) screening schemes have been in place in many countries for decades, attempting to reduce the incidence of this disease in the population. Importing sires with good hip dysplasia genetics from other countries may be of benefit in improving the gene pool with HD, by increasing genetic variability, and attempting to select against HD without importing sires can lead to inbreeding. However, different countries use different scales to estimate HD scores, which can decrease the efficacy of this strategy.
Wang et al7 used simulations to analyse the genetic change and inbreeding levels for different scenarios in which sires with high genetic merit for HD were imported. Real data from UK and Swedish populations of Labrador retrievers and golden retrievers were used in the models with respect to population size and genetic parameters, such as heritability and genetic correlation.
Where different HD scales were used in different countries, and an estimated breeding value (EBV) had been calculated, it was found to be useful to import sires if their EBV was in the top 50% and if high genetic correlations between the EBV systems existed. For the top 10% of EBVs in sires, only moderate accuracy of EBV and moderately strong genetic correlation was needed.
The authors concluded importing sires with high genetic merits can select against HD while maintaining genetic variability. However, when countries are using different HD scales to estimate breeding values, high genetic correlation is needed. The authors recommended a greater international consensus in HD screening protocols.
