Dr David Marlin discusses Blue Tongue
- What do we know?
- What do we THINK we know?
- What do we NEED to know?
Why have we only been seeing images fairly recently?
What can we learn from the photos we have seen? And why photos can’t tell us everything we need.
David also discusses a small pilot survey about Blue Tongue and what could be causing it.
https://embed.acast.com/636a2ad585c2b00011dbf45d/66f689c0067f94ba3faa8689
https://embed.acast.com/636a2ad585c2b00011dbf45d/66f689c0067f94ba3faa8689
Transcription
Here is a transcription of the podcast. (Please note this is an automated transcription, so we apologise for any errors from the original podcast.)
Hi, in this podcast, I’m going to be talking about blue tongues in horses. This is something that seems to have come around relatively recently. And what I want to try and cover in this podcast is what do we know about this? What do we think we know? And what do we need to know?
The starting point for this is really that images of horses with blue tongues, generally when being ridden, have started to appear more and more frequently. These are clearly quite disturbing. In some cases, the tongues are distorted by the bit and by perhaps heavy rein tension. Our obvious and instant reaction is that this isn’t normal.
A change in colour of the tissues when they go blue is referred to as cyanosis, and the blue colour is due to low oxygen tension, or what we call pressure. Venous blood, for example, is a darker blue colour than arterial blood, which has more oxygen and tends to be a much brighter red.
What I want to discuss is what we really know at this stage versus all the opinions that are circulating. It’s interesting that this is something that appears to have been noticed only relatively recently. Many of the images circulating on social media, in magazines, and even in documentaries have been taken by one particular photographer, who appears to be making a lot of money from selling them.
After one image was widely shared a few months ago, I contacted the photographer and asked if I could see the metadata for the image. Metadata is the data tagged to a photo or file that shows information such as when and where it was taken and whether it has been altered in any way. Interestingly, the photographer refused, and many people have raised the possibility that some of these images showing extremely blue and even distorted tongues may have been photoshopped to create a more striking effect. Obviously, if you’re looking to sell images, striking and extreme photos are the ones media outlets are more likely to buy and use.
As a follow-on from this, discussions on social media have led some people to initiate projects asking for submissions of images of horses’ tongues. Unfortunately, this approach isn’t going to provide any useful data. The colour captured in an image depends heavily on factors such as lighting, camera type, settings, and even the angle at which the photo is taken.
For example, lighting has a measurable colour temperature, expressed in Kelvins. Daylight is typically around 5600 Kelvins, while tungsten lighting (which has an orangey tone) is around 3200 Kelvins. Early morning light is even lower, at around 2000 Kelvins, giving it a reddish hue, whereas a bright blue sky can be as high as 10,000 Kelvins. Taking a photo of the same horse at different times of day will naturally produce differences in colour perception. This means that collecting images without strict standardisation of lighting, distance, exposure, and other settings will be unreliable for research purposes.
To get a better idea of how common blue tongues might be, a small survey was conducted. This was an attempt to structure the discussion rather than relying on unverified comments on social media. The survey had just four questions:
- Have you ever seen a horse (your own or someone else’s) with a blue tongue in person, rather than in a photo, video, or on TV?
- 7% said they had seen it once.
- 7% said they had seen it several times.
- 2% said they had seen it often.
- 84% said they had never seen it.
- For those who had seen it, was it on their own horse or someone else’s?
- 21% had seen it on their own horse.
- 79% had seen it on another horse.
- What discipline was the horse involved in at the time?
- Over half were in dressage.
- 11% were in driving.
- 11% were in racing.
- A few each were involved in showing, pleasure riding, and eventing/cross-country.
- What did respondents think was the cause of the blue tongue?
- 50% thought the horse was stressed or anxious.
- 39% thought rein tension was high.
- 39% couldn’t recall the exact circumstances.
- 28% said a double bridle was involved.
- A similar number said the horse’s head was behind the vertical for more than a few seconds.
- A similar number again said the horse appeared to be pulling hard.
- 10% believed it was linked to a severe bit.
- 5% thought it was related to head carriage.
Although this was only a small survey, it does suggest that people have observed horses with blue tongues. Following the survey and a post on this topic, around ten people privately shared their experiences of horses developing blue tongues.
- Three cases occurred while the horse was in the stable, tacked up but not being ridden, with a loose or undone noseband.
- Two cases occurred in horses at pasture, with no tack involved.
- The remaining cases occurred while being ridden, but most had only happened once.
Some riders offered to allow further observation to determine if it would happen again.
This topic has sparked significant debate, with some calling for riders whose horses develop blue tongues to face lengthy bans or even lifetime disqualifications. However, before taking such steps, we need to understand the cause. There is certainly evidence that some horses are developing blue tongues, but many questions remain unanswered. It could even be idiopathic, meaning it arises from an unknown or spontaneous cause.
To explore this further, here are some key questions:
- Are blue tongues the result of blood flow restriction, either into (arterial) or out of (venous) the tongue?
- Does it cause pain?
- If blood flow is restricted, where in the vascular system is this occurring—large vessels or tiny capillaries?
- What is the actual oxygen tension in the tongue before, during, and after a blue tongue develops?
- How quickly does it develop, and how quickly does it resolve?
- Is it more common in certain disciplines?
- What role do bits, rein tension, and head and neck position play?
- Do horses with blue tongues have normal vascular structures, or could there be congenital or acquired abnormalities?
- Could low oxygen tension in the tongue indicate low oxygen elsewhere in the body?
- Is there nerve damage involved?
- How reliable are photographs in assessing cyanosis severity?
- How can we measure tongue oxygenation during exercise?
- Do blue tongues occur in wild or non-exercising horses?
- Could it be related to upper airway obstruction?
- Once a horse develops a blue tongue, does it become more frequent or severe?
- Does it affect swallowing?
At this stage, there is simply not enough information to justify penalising riders, especially when we don’t fully understand why this occurs. More research is urgently needed to determine how common it is, why it happens, whether it causes pain, and whether it is related to training methods or tack. Only with evidence can we make informed decisions, whether through education, rule changes, or appropriate disciplinary action.
This is an issue the equestrian world needs to pay attention to – not only to protect social licence but also to improve horse welfare, which should be the priority for everyone involved in the industry.
