Fibrin

Fibrin is the protein that turns a bleeding dog wound into a protective scab. When your dog gets injured, the body converts the fibrinogen floating in the blood into fibrous fibrin networks, thus forming the clot that stops the bleeding.

Why does a scab form on dog wounds?

The enzyme thrombin cleaves fibrinogen and forms thread-like fibrin from it. These fibres network over the wound like a biological plaster. The resulting scab protects against bacteria and gives the tissue growing underneath time to heal.

You can see this process within minutes with small cuts on the paws. The bleeding stops, a reddish scab forms; that is fibrin at work.

When does fibrin become a problem?

It becomes problematic when the body produces too much fibrin or forms it in the wrong places. In severe inflammation, fibrin can deposit in body cavities; vets then speak of fibrinous inflammation.

An example: In fibrinous pleuritis, fibrin deposits between the lung and the ribcage. The dog struggles to breathe because the lung is no longer freely movable.

What are signs of coagulation problems?

You can recognise excessive fibrin formation by unusual symptoms: the dog suddenly limps without an apparent reason (possible thrombosis in the leg), has shortness of breath without exertion, or shows pale mucous membranes.

In disseminated intravascular coagulation (DIC), blood clots uncontrollably in small vessels. Paradoxically, this leads to a tendency to bleed because the clotting factors are used up.

How do vets treat fibrin disorders?

Treatment depends on the trigger. For thromboses, vets use anticoagulants such as heparin. Bacterial infections are treated with antibiotics to stop the excessive production of fibrin.

Surgical intervention may be necessary for fibrinous deposits in body cavities. Cortisone is used when autoimmune reactions drive the overproduction of fibrin.

When should you go to the vet with bleeding?

Normal minor injuries stop bleeding within 5–10 minutes. Book an appointment if the bleeding does not stop, the dog becomes apathetic, or the wound is gaping.

For large abrasions or deep cuts, go to the practice immediately; normal fibrin formation may not be sufficient here.