Under normal conditions, the blood circulates in an orderly manner inside the blood vessels and maintains a balance between the factors that favor and those that prevent coagulation. However, when there is an alteration in blood circulation, in the vessel wall or in blood coagulation, thrombi can be generated inside the blood vessels, which will cause a lack of irrigation in those organs or body regions normally supplied by these vessels.
If you want to know more about what is thrombosis in dogs, its treatment and symptoms , join us in the next article on our site in which we will explain the most important aspects of this pathology, its causes and diagnosis.
What is thrombosis in dogs?
Thrombosis is the pathological process characterized by the coagulation of the blood within the blood vessels or within the heart of a living animal. The blood passes from a liquid state to form a solid mass, called a thrombus, which totally or partially occludes the vessel in which it is located. This compromises the circulation in that vessel and hinders blood supply to the organs or body regions supplied by the affected vessels.
Thrombosis and embolism are terms that are often confused, however, do not mean exactly the same thing. Thrombi always remain attached to a vessel wall, however, emboli are parts of a thrombus that break off and travel through the bloodstream until they reach a vessel small enough to occlude it.
Although thrombi in dogs can be located in any blood vessel, it is more common to find them in:
- The pulmonary circulation.
- The renal circulation.
- The aortic circulation.
- Generalized throughout the circulatory system (multiorgan involvement).
The three mechanisms that can give rise to this pathological process are known as “Virchow's triad”, which includes:
- Alterations in blood flow: Turbulence, eddies or slowing phenomena (blood stasis) disorganize the flow columns in inside the vessel, which favors the formation of thrombi.
- Blood vessel wall injury: Blood circulates in an orderly manner; negatively charged platelets circulate around the periphery, and blood vessel endothelial cells also have a negative charge, causing them to repel each other. However, when the vessel endothelium is injured, the positively charged subendothelium is exposed, encouraging platelets to aggregate and bind to the vessel wall.
- Hypercoagulability states: there are certain pathologies that trigger an imbalance between pro-coagulant and anticoagulant factors, which favors the formation of thrombi.
Any of these causes, alone or in combination, can lead to thrombus formation directly.
Causes of thrombosis in dogs
What can cause thrombosis in dogs? As we have just explained, thrombosis occurs as a consequence of some of the alterations that make up Virchow's triad. Specifically, the causes that can give rise to each of these alterations are:
- Alterations in blood flow: heart disease (mainly endocarditis and endocardiosis), anatomical malformations, increased blood viscosity and prolonged decubitus.
- Blood vessel wall injury: Systemic Inflammatory Response Syndrome (SIRS), sepsis, heartworms, neoplasms, trauma severe injuries, injuries from injections or intravenous catheters, vasculitis, shock, atherosclerosis
- Hypercoagulable states: Cushing's syndrome, kidney disease, gastrointestinal diseases, pancreatitis, disseminated vascular coagulation (DIC), neoplasms and diseases heart rate.
In particular, thrombi in dogs are especially common in cases of sepsis, kidney disease and heart disease.
Symptoms of thrombosis in dogs
The symptoms of thrombosis occur as a consequence of the lack of blood supply (ischemia) of the organs or body regions normally supplied by the affected vessel. Some of the most common symptoms seen in cases of thrombosis in dogs are:
- Weakness or paralysis of the hind limbs (in case of aortic thrombosis).
- Skin paleness.
- No pulse.
- Pain in the affected body region.
- Hypothermia of the affected body region.
- Signs of failure: Depending on the affected organ, signs of kidney, liver, respiratory failure, etc. may appear.
Diagnosis of thrombosis in dogs
The patient's clinical symptoms may lead to suspicion of thrombosis, however, to reach a diagnosis of thrombotic disease it is necessary to carry out a series of complementary tests:
- Bloodwork: A blood sample should be taken from the patient to measure clotting times, platelet count, determination of fibrinogen, antithrombin and fibrin degradation products (PDFs and D-dimers). However, it must be taken into account that these laboratory tests are not specific for the diagnosis of thrombosis, so normal results should not rule out the disease.
- Colour Doppler Ultrasound: This is a type of ultrasound that assesses blood flow within blood vessels by display the speed and direction of blood in real time.
- Angiography: This is a type of contrast x-ray in which contrast material is introduced into blood vessels.
Although imaging tests allow diagnosing thrombotic disease, it is necessary to perform a battery of diagnostic tests in addition to discerning the possible cause of thrombosis. For this reason, in these animals it is advisable to carry out:
- Blood analysis: with full blood count and complete biochemical profile.
- Urinalysis: with protein/creatinine ratio.
- Echocardiography.
- Abdominal ultrasound.
- Chest x-ray.
Only in this way will we be able to determine the primary cause of the thrombosis and establish a treatment against it that prevents the formation of new thrombi.
Treatment of thrombosis in dogs
When thrombi are recent and small, the body is capable of destroying them thanks to the action of thrombolysin. However, in chronic cases or large thrombi, it is essential to establish a treatment based on the following points:
- Induce a state of hypocoagulability: to reduce thrombus formation. This is achieved through the use of fibrinolytic or antithrombotic drugs (such as heparin and clopidogrel).
- Surgery: When the patient's conditions allow it, it will be necessary to remove the thrombus by means of a thrombectomy technique (surgical or percutaneous by catheterization).), which restores blood flow in the affected vessel.
In addition, whenever possible, it will be necessary to establish a specific treatment for the underlying pathology that has given rise to the thrombotic phenomenon, to prevent the formation of new thrombi.
