Laryngeal chrondritis (LC), is an obstructive disease of the upper respiratory tract in sheep caused by abscesses on the larynx which, along with swelling and inflammation of the throat, restrict the windpipe.
It was found to be the most common cause of death among 170 rams on which veterinary surgeon Ben Strugnell, Hamsterley, carried out post-mortems from 2014-2019.
The problem was responsible for 17 per cent of deaths and a large proportion of these were Texels, which is why the disease is often referred to as ‘Texel throat’.
Trainee pathologist at the University of Nottingham, Katie Waine, who had been working with Mr Strugnell on the project said: “LC is seen in other breeds, but is more common in Texels and similar breeds, such as Beltex and Blue Texels.
“Although it has been well known for many years, up until recently there has been very little research into why this is the case and how it might be tackled.”
The larynxes of 23 Texel rams and 23 Bluefaced Leicester rams were removed and preserved following post-mortem and their anatomy compared and measured.
It was found that the larynxes of the Bluefaced Leicesters were larger and wider than those of the Texels with a clear airway through, whereas the Texel larynxes were narrower, the windpipe narrower and, in many cases, the vocal folds were touching, which was not the case with Bluefaced Leicesters.
Ms Waine said: “We also took measurements of the head and neck, but there did not seem to be any correlation between this and the anatomy of the larynx, although we cannot be sure.
“It is likely that the folds of the larynx rub together because they are so close, creating entry points for bacteria, which is naturally in the throat of sheep, leading to infection.”
Mr Strugnell said: “Not all Texels are like this and it does not always result in death. There is variation within the breed and with other breeds.
“However, there are a number of questions which need to be asked, such as how big is the problem; how can it be managed, what should we do and who should pay? This project is a starting point for the industry to see how breeding and selection may be used to address the problem.”
Reinard Everts, veterinary surgeon and managing director of the Dutch Sheep and Goat Breeders Organisation, said that Texel throat was also a problem in the Netherlands.
His recommendation was to select rams to be kept for breeding on a hot day to see to see how they coped, and to regularly observe sheep and any which had breathing difficulty when the temperature was above 20degC should not be retained for breeding.
The Texel Sheep Society has also been working with Scotland’s Rural College on a pilot to investigate any detectable laryngeal variation within the Texel breed with extra information being collected from animals CT scanned in Edinburgh.
The society’s research and development project manager, Ed Smith said: “We intend to continue collecting this information with the aim of building up data and keeping track of scanned animals through their life to see if they have any health issues.
“This should help us build up a picture of what is happening and if certain bloodlines are predisposed to the problem.”