Toxicology for Writers: Haemotoxins

Haemotoxins: A Bloody Problem

Welcome back to another page of toxicology for writers, haemotoxins. Haemotoxins (or hemotoxins) are toxins that damage blood cells or interfere with blood clotting. They usually cause damage to other organs as well. I will have a page where I explain the types and functions of blood cells in more detail but here’s a quick rundown. Then we’ll delve into the toxicology of haemotoxins.

First, red blood cells. They are biconcave, non-nucleated cells which contain haemoglobin (Hb), an iron and protein complex that binds oxygen. On the other hand, white blood cells are nucleated cells involved in immune responses and dealing with pathogens like viruses and bacteria. Platelets are tiny cells responsible for blood clotting.

Haemotoxins cause damage by destroying red blood cells or preventing blood from clotting. They damage other organs and cells in the body as well. Blood clotting is a complex process involving platelets, and a series of proteins and factors.

Haemotoxins: Haemolysis and Anaemia

Anaemia means not having enough red blood cells to meet the body’s oxygen needs. Examples of things that can cause anaemia include severe bleeding, medical conditions such as bone marrow disease and iron deficiency, and parasite infestations. Haemolysis means red blood cells are destroyed within the body, this basically means it causes the red blood cells to burst. Here’s a list of toxins that cause haemolysis:

• Quinine anti-malaria medications
• Arsenic poisoning
• Some antibiotics
• Snake venom: Viper and Cobra species

Haemotoxins: Anticoagulant Toxins

So, we all know the saying, “Blood is thicker than water.” Setting aside the true meaning for a minute, let’s look at the haemotoxins that block blood clotting, or blood thinners. Medications that stop blood clots are essential for people with DVT, heart attacks or strokes. A blood clot forming inside the body is very dangerous. However, overdose or inappropriate use will cause a coagulation disorder, which is also very dangerous!

Anticoagulant Haemotoxins: Coumarins

Coumarins are a class of substances that prevent blood from clotting. Many people take warfarin if they have previously had a heart attack or stroke. Other coumarins are used in rat poisons, killing rodents by causing them to bleed uncontrollably. It takes a few days to weeks to take effect. Rodenticide toxicity is common in dogs and other species, either directly from eating the rat poison or from eating rodents that have eaten the poison.

I have seen cases of secondary poisoning, one in a dog and one in a bird of prey. Luckily, there is an antidote, vitamin K. Cases need treatment for a number of weeks. Unlike many other toxins, symptoms of coumarin ingestion don’t appear for a week or two after ingestion. Don’t wait though, seek advice immediately.

Other medications that prevent blood clotting include heparin, Non-Steroidal Anti-Inflammatory Drugs (NSAIDs) such as aspirin, and clopidogrel. Patients taking these medications must be cautious as even a small cut can bleed excessively. Some snake venoms also have anticoagulant effects.

Consequences of Anticoagulant Toxicity

You might think that thinning the blood isn’t that bad, but it can be very serious. Microtears in blood vessels happen all the time, but the body can deal with it via blood clotting. If the body can’t do this, blood will be lost through all areas of the body. Symptoms can include bruising, petechiae (microbruises), blood in urine, bleeding from the bowels, gums, stomach and nose.

This can become serious very quickly, and may even progress to internal bleeding or a bleed in the brain. Any injury, even a minor one, will become much more serious. Anaemia will develop due to loss of blood, which will lead to lethargy, weakness and eventually could lead to shock. This can kill.

Treatment of clotting disorders requires vitamin K supplementation, replacement of clotting factors (blood plasma infusion) and platelet transfusion. Whole blood transfusion may be needed in severe cases. You do want your blood to be thicker than water, at least in the most literal sense!

Conclusion

So that was a brief rundown of toxins that attack the blood. Blood is life, it’s essential for us to keep working. Without it, our cells would not get the oxygen, nutrients and water they need to keep functioning. So it’s an effective target for poisons, hence why anticoagulants are used for rodent control. I make no comment on the ethical side of this, as pest control is a part of disease control and it’s not a simple question to answer. At least there are options to treat accidental poisoning in some cases.

I hope you find this page useful. As always, this is about providing information only and is not a substitute for medical advice, nor is it encouraging anything against the law. Toxicology for writers, haemotoxins, is merely a resource for writers to inform their fictional works. For more, see the other pages. I hope you enjoy this series.

• TikTok
• Instagram
• Facebook
• YouTube