Equine SAA: The Inflammation Marker in Horses

Serum amyloid A, or SAA, is a protein that a horse's liver releases when the body has inflammation, and a blood test can measure it. SAA rises quickly when inflammation begins and falls quickly as it settles, so vets use it to spot inflammation and to follow recovery. It cannot say what is causing the problem.

What is SAA?

Inflammation is the body's reaction to germs or injury, and it can bring heat, swelling and fever. When it starts, the liver makes more of certain proteins and sends them into the blood. These are called acute-phase proteins, and SAA is one of them. In a healthy horse the SAA level is very low, so a rise stands out clearly.

The Equine Serum Amyloid A (SAA) measures SAA in a blood sample. It is a test made for horses, and foals can be tested too, although the vet reads a foal's result with its age in mind.

Why do vets like a fast marker?

Many blood markers of inflammation move slowly. SAA reacts quickly, so it may show a problem early, when a horse is only a little off colour and has few other signs. Because it also falls quickly once the inflammation eases, a second test taken a little later shows which way things are going.

Infections of the breathing passages, wounds, joint trouble, surgery and some gut problems may all raise SAA. The result is a clue that something is inflamed. It is your vet's examination that finds where.

How do SAA, fibrinogen and CBC fit together?

Each test shows a different side of inflammation.

• SAA reacts fast and falls fast, so it is useful for early signs and for follow-up.
• The Plasma Fibrinogen measures a clotting protein made by the liver. It also rises with inflammation, but more slowly, and it stays high for longer.
• The Complete Blood Count (CBC) counts red cells, white cells and platelets. White cell changes can point to infection, and anaemia (too few red cells) may show that a long illness is wearing the horse down.

Together they give your vet a fuller picture than any one alone. For a horse with fever and cough, the Horse Fever & Respiratory RT-PCR Panel typically combines RT-PCR tests for respiratory germs with a CBC and an SAA test. The exact list is confirmed when you book.

How is SAA used to follow recovery?

A vet may take a first sample when the horse falls ill and another one later. If SAA falls, it suggests that the inflammation is settling. If it stays high or climbs again, your vet may look again for a hidden problem, such as an abscess (a pocket of pus), a second infection or a wound that is not healing.

The number is only a guide. Your vet, not the result, decides about rest, return to work and any treatment, and a falling value is read together with how the horse looks and behaves.

How is the sample collected?

Your vet draws blood from a vein in the neck. SAA, fibrinogen and a CBC may each need a different kind of tube, so ask the lab which ones to use before the blood is taken. Label the tubes with the horse's name and the date, and keep them cool.

What can SAA not tell you?

SAA does not name the germ. A virus, a bacterium, a wound and an operation can all raise it, and it does not show which part of the body is affected. A normal result does not rule illness out either, because a small or local problem may not raise SAA much.

A horse that looks unwell still needs to see a vet, and urgent care should never wait for a lab result. Think of SAA as one clue that your registered veterinarian puts together with the examination and the horse's history.

Read next

Surra in Horses: Trypanosoma evansi Tests and Tick Fever in Horses: Equine Piroplasmosis Testing describe two blood-borne illnesses that can make a horse feverish. SAA can show that inflammation is present, but only those specific tests look for the parasites themselves.

Testing in Bhopal

The vet usually draws the blood, and the lab at C-200, C Sector, Shahpura, Bhopal collects samples free of charge anywhere in Bhopal. If your stable is in another district, your vet can send the tubes by courier or bus parcel. Before you book, call or WhatsApp +91 88175 01118. The lab confirms the method, sample needs and reporting time at that point.