As Halloween approaches get ready for the witches, broomsticks, black cats and rats to be out and about in the full force of fancy dress. You may notice that rats get a really rough deal; they’re often portrayed as the bad-guys in films and decorations. They do have one unusual trait that can be a little more ‘trick’ than ‘treat’, however!

Those of you that have owned rats may have noticed that they can occasionally get red or orange staining or crusting around their eyes and nose. This can give the appearance that they have been crying or sneezing blood – perhaps they are the scary little creatures we see in Halloween films? Or maybe there’s something else behind it…


The fancy name for this condition is actually ‘chromodacryorrhea’ or ‘red tears’ and is caused by a pigment in the normal tears of a rat. You may see an increase of a pink, red or orange liquid around the eyes or nose of your rat. This can give the appearance they have been sneezing or crying blood-tinged fluid. As the colour can vary in intensity, it can look severe and be quite concerning.  


If it’s not blood, what is it? 

Lots of mammals have third-eyelids (this is the pink bit you sometimes can see at the inner corner of cats/dogs eyes). Those with third-eyelids also possess an extra lacrimal gland (or tear gland) called the Harderian gland. In humans this gland is really small, and doesn’t really do anything. In rodents (including ratties!) this gland is larger and has an important function. 

This gland secretes a mixture of lipids (oils/fats) and products called melatonin and porphyrin. These secretions function to lubricate the eye and third eyelid, produce pheromones (chemical messages) and help to protect the retina (back of the eye) from ultraviolet (UV) light. 

It is these porphyrins, which are secreted by the gland, that are responsible for the red colouration given to the rat’s tears and are to blame for them “crying blood”.


 Prophyrin facts:

  • It is produced and stored within the gland itself. 
  • Production increases as a rat ages (until around 2 years of age), then decreases again after that age. 
  • It will fluoresce (glow!) under UV light and your vet can use this fact to differentiate between blood or porphyrin secretions. 


Why is this important?

A very small amount of porphyrin staining around the eyes and nostrils can be normal; your rat should clean this by themselves during normal grooming. However, an increase can indicate an underlying health issue. 

Remember that there are some situations where your rat may actually be sneezing blood or may have injured themselves, and if you are concerned you must speak to or visit your vet for a health check. 

 Reasons for an increase in production include: 

  • Environmental stressors = arguments between cage-mates, overcrowding, competition for food, household noise.
  • Irritants = bedding materials, scented air-fresheners/candles in the home, strong cage disinfectants, smoking.
  • Illness:
    • Dental disease
    • Respiratory disease = bacterial or viral infections
    • Skin disease/tumours
    • Other
  • Eye issues = infection, trauma to the eye, blocked tear ducts
  • Poor nutrition = lack of access to good food or poor appetite
  • Dehydration 


What do we do about it? 

An increase or sudden production of red tears is a symptom of an underlying issue this is important. 

If your rat is not well then you must take him or her to a vet for a health check as soon as there are any signs of illness – I cannot stress this enough.  

At a health check your vet will check the front teeth, listen to the heart, lungs and examine for any other issues; of course, this depends on how wriggly your rat is for the examination!  Whether or not there are concerns raised at the health-check you need to review your management at home: 

  • Reduce stress in the household
  • Ensure your rat’s housing is appropriately sized (for the number in there!)
  • Provide enrichment (toys/climbing) to help reduce stress 
  • Check your bedding material; avoid scented or dusty materials
  • Don’t smoke (or allow others to!) around your pets
  • Ensure good quality food is available and that there’s enough for everyone to avoid competition.
  • Provide fresh water (bowls and/or bottles), change this daily. 


Remember, it’s not just hocus-pocus…

The sooner you start treatment for a condition or improve management at home then the better the chance of a positive outcome, and most importantly – the better your rat’s quality of life.