Mycotoxins – When food goes bad 

Written by HeIdi Hilburn RVN
September 21, 2023

Why is mould poisonous?

Mycotoxins are produced by mould species. Mould is a type of fungus. Moulds like to grow on spoiled food or organic matter like plant material. There are over 300,000 species of mould and they can be either harmful or harmless.  

Some moulds produce highly poisonous substances known as mycotoxins, and it’s these mycotoxins that can be fatal if our pets eat them. Not all moulds produce dangerous mycotoxins, but it is impossible to tell by looking at them as they do all just look like mould. 

Which mycotoxins are a concern for our pets?

There are many types of mycotoxins. They are split into different groups. 

The most common group is: 

Tremorgenic mycotoxins - The moulds found on decaying food and organic material produce tremorgenic mycotoxins. 

Another form of mycotoxin is: 

Aflatoxins – The moulds found growing on plants and plant products produce Aflatoxins. This type of mycotoxin is less common in the UK.  

Where can they be found?

Mycotoxins are found where there is mould. Primarily mould grows where the environment is warm and humid. 

Unlike plants, mould is a fungus and doesn’t grow from seed, instead they grow from tiny spores that float around in the air. When these spores land in an environment that has adequate moisture, correct temperature, and good oxygen supply, the spores grow into mould, some of which may produce these toxic substances called mycotoxins. It is these mycotoxins that have the potential to cause serious health issues for our pets. 

Places tremorgenic toxins are found. 

  • Mouldy dairy products 
  • Mouldy bread 
  • Mouldy cheese 
  • Mouldy fruit and nuts (that has fallen from the tree) 
  • Food waste 
  • Rubbish 
  • Compost

Places aflatoxins are found.  

  • Mouldy corn  
  • Mouldy Nuts such as peanuts  
  • Mouldy grain 
  • Old or contaminated pet food

When do mycotoxins occur?

Tremorgenic mycotoxins 

When food waste is disposed of into the bin, it is often a warm, humid environment. This is perfect for spores that have landed on the food, to grow into mould with the potential to produce these highly poisonous tremorgenic mycotoxins.

Aflatoxin mycotoxins 

This type of mould is less common in the UK thankfully, but it could occur on ingredients that go into pet food like types of grain, or more commonly may occur during storage, particularly if there is high humidity and temperatures.

Why is it dangerous for our pets to eat mouldy food?

Pets that eat mouldy food can become ill very quickly. You may have seen them eat the mouldy food or noticed that they have become unwell and are showing some of the signs listed below. Mycotoxin poisoning and the effects it can have on your pet can be fatal, therefore the sooner your pet receives treatment the better the outcome is for them.

Who is at risk of poisoning?

  • Pets that raid bins which have mouldy food waste in them. 
  • Curious dogs that are unattended in the garden which has a compost area, where decaying organic matter like fallen fruits, nuts, silage or rubbish can be found.
  • Pets fed contaminated pet food or food that has been stored incorrectly.  

Common symptoms of tremorgenic mycotoxin poisoning can include: 

  • Vomiting 
  • Wobbliness 
  • Tremors 
  • Agitation and hyperactivity 
  • High temperature and panting  

Common Symptoms of Aflatoxin poisoning can include: 

  • Vomiting 
  • Diarrhoea 
  • Increased thirst  
  • Lethargy 
  • Jaundice (yellowing of the mucus membranes, skin and whites of the eye). 

How to prevent mycotoxin poisoning 

Top tips: 

  • Don’t feed mouldy leftovers to your pet, food that is out of date for humans will likely be toxic to our pets. 
  • Rubbish bins should be out of reach of your pet, maybe secured in a cupboard with a child lock on it. 
  • Empty your rubbish bins regularly and carefully, into a secure bin outside.  
  • Ensure the outside waste bin is a sealed container with a lid that your pet can’t remove! 
  • Train your dog the ‘leave it’ command (especially useful if they try to pick something up off the floor) 
  • Supervise your pets’ visits to the garden so they don’t have access to a compost heap or a fruit tree that may have fallen fruit. 
  • Consider having a secure container to put your compostables in  
  • Clean your pet’s storage container out before tipping in a new bag of food, ensure the food container has been completely dried before putting the new food in it. 
  • Make sure your pets food storage container is: airtight, not in direct sunlight, kept away from any moisture or humidity. 

Aflatoxin poisoning is much less of a concern to our pets in the UK, but moulds that produce tremorgenic mycotoxins can be a worry. By following the simple top tips above, you will be preventing your pet from encountering these moulds. 

Although pet food that includes grain has a slightly higher risk of containing aflatoxin-producing moulds, with proper storage this risk diminishes greatly. It's important to consider all aspects of the food when finding what fits best for your pet, including its storage requirements.  

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