New genetic test will eliminate a form of inherited blindness in dogs
Progressive retinal atrophy (PRA) is a group of inherited diseases that causes progressive degeneration of the light sensitive cells at the back of the eye. Dogs with PRA have normal sight at birth, but by the age of four or five they will be totally blind. There is no treatment.
Now a team led by the University of Cambridge has identified the genetic mutation that causes PRA in English Shepherd Dogs, and developed a DNA test for it. By identifying dogs carrying the disease before their eyesight starts to fail, this provides a tool to guide breeding decisions so the disease is not passed on to puppies.
Owners usually don’t realise their dog has PRA until it is middle-aged, by which time it might have bred, and passed on the faulty gene to its puppies. This has made it a difficult disease to control.
The new discovery means that progressive retinal atrophy can now be completely eliminated from the English Shepherd Dog population very quickly.
The results are published today in the journal Genes.
“Once the dog’s eyesight starts to fail there’s no treatment – it will end up totally blind,” said Katherine Stanbury, a researcher in the University of Cambridge’s Department of Veterinary Medicine and first author of the report.
She added: “Now we have a DNA test, there’s no reason why another English Shepherd Dog ever needs to be born with this form of progressive retinal atrophy – it gives breeders a way of totally eliminating the disease.”
The genetic mutation identified by the team is recessive, which means it only causes blindness if the English Shepherd Dog inherits two copies of it. If the dog only has one copy this makes it a carrier – it will not develop PRA but can pass the mutation on to its puppies. If two carriers are bred together, about one in four of the puppies will be affected with PRA.
Dogs breeds are very inbred, so many individuals are related – giving them a much higher chance of being affected by recessive diseases than humans.
The team began the research after being contacted by a distraught owner of an English Shepherd Dog that had been recently diagnosed with PRA. The dog had been working as a search and rescue dog but had to retire due to visual deterioration that has resulted in total blindness. The researchers put out a call for DNA samples from other owners or breeders of this breed, and received samples from six English Shepherds with PRA and twenty without it. This was enough for them to pinpoint the genetic mutation responsible for PRA using whole genome sequencing.
The team offers a commercial canine genetic testing service providing DNA tests to dog breeders to help them avoid breeding dogs that will develop inherited diseases. As part of this they will now offer a DNA test for Progressive Retinal Atrophy in English Shepherds. Anyone can buy a testing kit, costing just £48, to take a swab from inside their dog’s mouth and send it back for testing.
“An owner won't necessarily notice their dog has got anything wrong with its eyes until it starts bumping into the furniture. Unlike humans who will speak up if their sight isn’t right, dogs just have to get on with things,” said Dr Cathryn Mellersh in the University of Cambridge’s Department of Veterinary Medicine, senior author of the report.
She added: “For the price of a decent bag of dog food people can now have their English Shepherd tested for Progressive Retinal Atrophy prior to breeding. It’s about prevention, rather than a cure, and it means a huge amount to the people who breed these dogs. They no longer need to worry about whether the puppies are going to be healthy or are going to develop this horrible disease in a few years’ time.”
The English Shepherd is a breed of herding dog popular in the United States and is closely related to the Border Collie.
The new discovery is the thirty-third genetic mutation causing an inherited disease in dogs that the team has found – twenty-three of which cause eye diseases. They say that the health and wellbeing of many dogs has been compromised because of how they have been bred by humans.
PRA occurs in many dog breeds including the English Shepherd Dog. And it is similar to a disease called retinitis pigmentosa in humans, which also causes blindness. The researchers say that their work with dogs could shed light on the human version of the disease and potentially identify targets for gene therapy in the future.
The work was carried out in collaboration with Wisdom Panel, Mars Petcare, as part of the Consortium to Research Inherited Eye Diseases in Dogs (CRIEDD), with funding from the Dog’s Trust and the Kennel Club Charitable Trust.
Reference: Stanbury, K. et al, ‘Exonic SINE insertion in FAM161A is associated with autosomal recessive progressive retinal atrophy in the English Shepherd.’ July 2024.
Cambridge scientists have identified the genetic mutation that causes progressive retinal atrophy in English Shepherd Dogs, which results in incurable blindness, and developed a genetic test to help eliminate the disease from future generations of the breed.
animal healthgeneticsKatherine StanburyCathryn MellershWisdom PanelDepartment of Veterinary MedicineSchool of the Biological SciencesNow we have a DNA test, there’s no reason why another English Shepherd Dog ever needs to be born with this form of progressive retinal atrophy – it gives breeders a way of totally eliminating the disease.Katherine StanburyEnglish Shepherd puppy
The text in this work is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License. Images, including our videos, are Copyright ©University of Cambridge and licensors/contributors as identified. All rights reserved. We make our image and video content available in a number of ways – on our main website under its Terms and conditions, and on a range of channels including social media that permit your use and sharing of our content under their respective Terms.
Pork labelling schemes ‘not helpful’ in making informed buying choices, say researchers
Researchers have evaluated different types of pig farming – including woodland, organic, free range, RSPCA assured, and Red Tractor certified, to assess each systems’ impact across four areas: land use (representing biodiversity loss), greenhouse gas emissions, antibiotics use and animal welfare. Their study concludes that none of the farm types performed consistently well across all four areas – a finding that has important implications for increasingly climate conscious consumers, as well as farmers themselves.
However, there were individual farms that did perform well in all domains, including an indoor Red Tractor farm, an outdoor bred, indoor finished RSPCA assured farm and fully outdoor woodland farm. “Outliers like these show that trade-offs are not inevitable,” said lead author Dr Harriet Bartlett, Research Associate at the University of Oxford's Smith School of Enterprise and the Environment, who was formerly at the University of Cambridge.
“Somewhat unexpectedly we found that a handful of farms perform far better than average across all four of our environmental and welfare measures,” added senior author Andrew Balmford, Professor of Conservation Science at the University of Cambridge. However, none of the current label or assurance schemes predicted which farms these would be.
“The way we classify farm types and label pork isn’t helpful for making informed decisions when it comes to buying more sustainable meat. Even more importantly, we aren’t rewarding and incentivising the best-performing farmers. Instead of focusing on farm types or practices, we need to focus on meaningful outcomes for people, the planet and the pigs – and assess, and reward farms based on these,” said Bartlett.
The findings also show that common assumptions around food labelling can be misplaced. For instance, Organic farming systems, which consumers might see as climate and environmentally friendly, have on average three times the CO2 output per kg of meat of more intensive Red Tractor or RSPCA assured systems and four times the land use. However, these same systems use on average almost 90% fewer antibiotic medicines, and result in improved animal welfare compared with production from Red tractor or RSPCA assured systems.
The way we classify livestock farms must be improved, Bartlett says, because livestock production is growing rapidly, especially pork production, which has quadrupled in the past 50 years and already accounts for 9% of greenhouse gas emissions from livestock. Pig farming also uses more antibiotics than any other livestock sector, and 8.5% of all arable land.
“Our findings show that mitigating the environmental impacts of livestock farming isn’t a case of saying which farm type is the best,” said Bartlett. “There is substantial scope for improvement within types, and our current means of classification is not identifying the best farms for the planet and animals overall. Instead, we need to identify farms that successfully limit their impacts across all areas of societal concern, and understand, promote and incentivise their practises.”
The study reached its conclusions using data from 74 UK and 17 Brazilian breed-to-finish systems, each made up of 1-3 farms and representing the annual production of over 1.2 million pigs. It is published today in the journal Nature Food.
“To the best of our knowledge, our dataset covers by far the largest and most diverse sample of pig production systems examined in any single study,” said Bartlett.
James Wood, Professor of Equine and Farm Animal Science at the University of Cambridge, commented: “This important study identifies a key need to clarify what different farm labels should indicate to consumers; there is a pressing need to extend this work into other farming sectors. It also clearly demonstrates the critical importance that individual farmers play in promoting best practice across all farming systems.”
Trade-offs in the externalities of pig production are not inevitable was authored by academics at the University of Oxford, University of Cambridge and the University of São Paulo.
The research was funded by the Biotechnology and Biological Sciences Research Council (BBSRC).
Reference: Bartlett, H.,‘Trade-offs in the externalities of pig production are not inevitable.’ Nature Food, April 2024. DOI: 10.1038/s43016-024-00921-2
Adapted from a press release by the University of Oxford.
Farmers don’t have to choose between lowering environmental impact and improving welfare for their pigs, a new study has found: it is possible to do both. But this is not reflected in the current food labelling schemes relied on by consumers.
food systemGlobal food securityEnvironmentHarriet BartlettJames WoodMark HolmesAndrew BalmfordUniversity of OxfordUniversidade de Sao PauloDepartment of Veterinary MedicineDepartment of ZoologySchool of the Biological SciencesCambridge Global Food Security Interdisciplinary Research CentreChurchill CollegeThe way we classify farm types and label pork isn’t helpful for making informed decisions when it comes to buying more sustainable meat.Harriet BartlettCharity Burggraaf/ GettyTwo pigs on a farm
The text in this work is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License. Images, including our videos, are Copyright ©University of Cambridge and licensors/contributors as identified. All rights reserved. We make our image and video content available in a number of ways – on our main website under its Terms and conditions, and on a range of channels including social media that permit your use and sharing of our content under their respective Terms.