# Blood Destruction II (DD-598)

> Many snake venoms, especially those of vipers (the family that includes rattlesnakes), are haemotoxic: they act on blood and blood vessels. A 2017 review in the British Journal of Haematology by Slagboom and colleagues describes three main routes. First, snake venom metalloproteinases (SVMPs) digest the basement membrane that supports capillary walls, especially type IV collagen. A 2016 review by Gutiérrez and colleagues explains that the weakened capillaries are then torn apart by the normal pressure of blood flow, so blood leaks into the tissue. Second, procoagulant toxins activate clotting factors such as Factor X and prothrombin, or act directly on fibrinogen. Inside the body this burns through the clotting factors, a condition called venom-induced consumption coagulopathy (VICC), and the blood ends up unable to clot. That's why a bite can cause both clotting and bleeding. Third, toxins such as disintegrins and C-type lectins can block platelets from clumping, or activate them until they're used up. Slagboom and colleagues cite about 1.8 million snake envenomings and up to 125,000 deaths a year. The same toxins are studied as drugs and diagnostic tools. The footage shows venom being collected from a snake held over a covered jar, then drawn into a syringe and added to blood in a glass, where the blood quickly thickens into a clot, a lab-glass illustration of the procoagulant effect. The snake isn't identified.

- Department: Nature (also Science)
- First published: 2025-06-17
- Last updated: 2025-06-17
- Permalink: https://detailenjoyer.com/case/blood-destruction-ii/
- Author: Marcus Easterling (DetailEnjoyer), The Detail Department

## Quick facts

- **DD-598-F01**: Snake venom metalloproteinases break down capillary walls. _(Write-up · Exhibit A (Vessel walls give way))_
- **DD-598-F02**: Venom can clot blood and then leave it unable to clot. _(Write-up · Exhibit A (Vessel walls give way))_

## Write-up

Venom that unmakes blood. Viper venoms attack clotting, platelets and vessel walls.

1. **Vessel walls give way**: Metalloproteinases digest the capillary basement membrane, and blood pressure then tears the vessel open.
2. **Clots that cause bleeding**: Procoagulant toxins use up clotting factors, leaving blood that can no longer clot (VICC).
3. **Platelets disabled**: Disintegrins and other toxins block platelet clumping or use platelets up.
4. **Mostly vipers**: Most snakes known to cause VICC are vipers, the family that includes rattlesnakes.
5. **A global toll**: Slagboom and colleagues cite about 1.8 million envenomings and up to 125,000 deaths a year.

## Related case files

- [Blood Destruction (DD-395)](https://detailenjoyer.com/case/blood-destruction/): I linked the first part of the Blood Destruction series, on how malaria parasites destroy red blood cells
- [insularis blue (DD-628)](https://detailenjoyer.com/case/insularis-blue/): Another case about a venomous pit viper
- [Blood Watch (DD-649)](https://detailenjoyer.com/case/blood-watch/): Another look at blood and blood vessels

## Reel vs. record

- **Note**: 'Causing uncontrolled bleeding or dangerous clots': both can happen, and often in the same patient. Procoagulant toxins trigger clotting, which uses up fibrinogen and other factors (venom-induced consumption coagulopathy), so the blood then can't clot.
- **Note**: 'Enzymes break down vessel walls': yes. Snake venom metalloproteinases digest the capillary basement membrane, especially type IV collagen, and blood-flow forces then rupture the weakened vessel.
- **Note**: 'Platelets fail to aggregate properly': some toxins block platelet aggregation, but others activate platelets. Either way, platelets end up depleted.
- **Note**: 'Like those from rattlesnakes': rattlesnakes are vipers, and most snakes known to cause consumption coagulopathy are vipers. Some Australasian elapids and some colubrids can cause it too.
- **Footage**: venom added to blood in a glass makes it clot quickly, which illustrates the procoagulant effect rather than the bleeding the captions describe.

## Video: Blood Destruction II: Venom That Unmakes Blood

- Duration: 16.4 s · Published: 2025-06-17
- File: https://detailenjoyer.com/assets/videos/DLBRZBkywmp.mp4

### Transcript

DID YOU KNOW? Snake venom's impact on human blood is a striking biochemical process. Hemotoxic venoms, like those from rattlesnakes, disrupt blood clotting, causing uncontrolled bleeding or dangerous clots. The venom's enzymes break down vessel walls, leading to hemorrhage, while platelets fail to aggregate properly. NOW YOU KNOW!

## Questions & answers

**Q: Which venom enzymes break down capillary walls?**  
A: Snake venom metalloproteinases (SVMPs). _(Source: Write-up · Exhibit A (Vessel walls give way) · Gutiérrez et al. (2016): Hemorrhage caused by snake venom metalloproteinases: a journey of discovery and understanding, Toxins (PMC); Kini & Koh (2016): Metalloproteases affecting blood coagulation, fibrinolysis and platelet aggregation from snake venoms, Toxins (PMC))_

**Q: What does VICC stand for?**  
A: Clotting factors get used up. _(Source: Write-up · Exhibit B (Clots that cause bleeding) · Slagboom et al. (2017): Haemotoxic snake venoms: their functional activity, impact on snakebite victims and pharmaceutical promise, British Journal of Haematology (PMC); Kini & Koh (2016): Metalloproteases affecting blood coagulation, fibrinolysis and platelet aggregation from snake venoms, Toxins (PMC))_

**Q: Which protein runs low in VICC?**  
A: Leaving blood that can't clot. _(Source: Write-up · Exhibit B (Clots that cause bleeding) · Slagboom et al. (2017): Haemotoxic snake venoms: their functional activity, impact on snakebite victims and pharmaceutical promise, British Journal of Haematology (PMC); Kini & Koh (2016): Metalloproteases affecting blood coagulation, fibrinolysis and platelet aggregation from snake venoms, Toxins (PMC))_

**Q: Which snake family causes most VICC cases?**  
A: Rattlesnakes are vipers. _(Source: Write-up · Exhibit D (Mostly vipers) · Slagboom et al. (2017): Haemotoxic snake venoms: their functional activity, impact on snakebite victims and pharmaceutical promise, British Journal of Haematology (PMC))_

**Q: About how many snake envenomings happen each year, per the 2017 review?**  
A: With up to 125,000 deaths. _(Source: Write-up · Exhibit E (A global toll) · Slagboom et al. (2017): Haemotoxic snake venoms: their functional activity, impact on snakebite victims and pharmaceutical promise, British Journal of Haematology (PMC))_

## Sources

- [Slagboom et al. (2017): Haemotoxic snake venoms: their functional activity, impact on snakebite victims and pharmaceutical promise, British Journal of Haematology (PMC)](https://pmc.ncbi.nlm.nih.gov/articles/PMC5484289/)
- [Gutiérrez et al. (2016): Hemorrhage caused by snake venom metalloproteinases: a journey of discovery and understanding, Toxins (PMC)](https://pmc.ncbi.nlm.nih.gov/articles/PMC4848620/)
- [Kini & Koh (2016): Metalloproteases affecting blood coagulation, fibrinolysis and platelet aggregation from snake venoms, Toxins (PMC)](https://pmc.ncbi.nlm.nih.gov/articles/PMC5086644/)

## Cite this case file

Easterling, Marcus. "Blood Destruction II." The Detail Department (DetailEnjoyer), case file DD-598, last updated Jun 17, 2025. https://detailenjoyer.com/case/blood-destruction-ii/