The intricate network of blood vessels within cats forms their circulatory system, a dynamic internal transport system. These vessels circulate blood throughout the feline body, delivering oxygen, nutrients, hormones, and immune substances to tissues and organs. They also collect waste products and carbon dioxide for elimination, playing a role in maintaining body temperature and fluid balance. This continuous flow is fundamental for every bodily function.
How Blood Vessels Work in Cats
The feline circulatory system operates as a closed loop, where blood is continuously pumped by the heart through three primary types of blood vessels: arteries, veins, and capillaries. Arteries are muscular vessels that carry oxygenated blood away from the heart to various parts of the body. They branch into smaller arterioles, which regulate blood flow into the capillary beds.
Capillaries are the smallest and most numerous blood vessels, forming a vast network within tissues. Their walls are extremely thin, allowing for the efficient exchange of oxygen, nutrients, and waste products between the blood and surrounding cells. After this exchange, deoxygenated blood flows from the capillaries into tiny venules.
Venules then merge to form larger veins, which carry deoxygenated blood back towards the heart. Unlike arteries, veins have thinner walls and contain one-way valves that prevent blood from flowing backward, ensuring its steady return to the heart. The blood completes its circuit by entering the right side of the heart, then travels to the lungs for re-oxygenation, before returning to the left side of the heart to be pumped back into systemic circulation.
Key Vascular Diseases in Cats
Cats can experience several vascular diseases that impact their overall health. Hypertension, or high blood pressure, is common, particularly in older cats, affecting approximately 1 in 5 felines over nine years of age. This condition is frequently secondary to underlying issues such as chronic kidney disease or hyperthyroidism, where the increased metabolic rate can elevate blood pressure. Untreated hypertension can lead to damage in organs like the eyes, brain, heart, and kidneys, potentially causing sudden blindness due to retinal vessel damage or detachment.
Thrombosis and embolism involve the formation of blood clots that can obstruct blood flow. A particularly severe form in cats is feline aortic thromboembolism (FATE), often called a “saddle thrombus.” This occurs when a blood clot, originating from the heart due to underlying heart disease, dislodges and travels down the aorta. The clot commonly lodges at the “saddle”—the point where the aorta branches to supply blood to the hind legs—leading to sudden paralysis, severe pain, and cold limbs due to compromised blood supply.
Heartworm disease, caused by Dirofilaria immitis parasites, primarily affects the pulmonary arteries and heart. Even a small number of worms can cause inflammation and damage to the pulmonary vessels and lung tissue, leading to Heartworm Associated Respiratory Disease (HARD). This can result in symptoms such as coughing, wheezing, and difficulty breathing, or sudden death.
Vasculitis involves inflammation of the blood vessel walls, which can lead to vessel destruction and reduced blood flow to tissues. This condition can manifest as ulcers, crusted lesions, or bruising on the skin. It is a reaction to an abnormal immune response, which might be triggered by infections or certain medications.
Congenital vascular defects are structural abnormalities present from birth. One example is Patent Ductus Arteriosus (PDA), where a fetal blood vessel connecting the aorta and pulmonary artery fails to close after birth. This allows oxygenated blood to recirculate to the lungs, increasing the workload on the heart and leading to heart failure or pulmonary hypertension. Another defect, portosystemic shunts, involves abnormal vessels that allow blood from the digestive system to bypass the liver, leading to a buildup of toxins in the systemic circulation.
Diagnosing and Managing Feline Vascular Health
Recognizing signs that suggest a vascular problem is important for prompt veterinary intervention. Owners might observe lethargy, weakness, changes in breathing patterns, or a sudden onset of lameness. Other signs include changes in appetite, unexplained weight loss, or visible swelling. If any of these signs appear, seek veterinary consultation promptly.
Veterinarians employ a range of diagnostic tools to assess feline vascular health. A physical examination includes listening to the heart and lungs with a stethoscope to detect abnormal sounds like murmurs or irregular rhythms, and palpating pulses. Blood tests and urinalysis provide insights into organ function and can indicate underlying conditions, such as kidney disease or hyperthyroidism.
Blood pressure measurement, often performed using a cuff on the leg or tail, helps identify hypertension. Imaging techniques like X-rays can reveal heart enlargement or fluid accumulation in the lungs. Ultrasound offers detailed views of the heart’s structure and blood flow, aiding in diagnosis. Specialized angiography may be used to visualize blood vessels.
Management approaches for feline vascular conditions vary depending on the specific diagnosis. Medications are a common treatment, including anti-hypertensives like amlodipine to lower blood pressure, or anti-coagulants to prevent blood clot formation. For heartworm disease, managing symptoms with medications like prednisolone to reduce inflammation is an option, alongside prevention.
Dietary changes may be recommended, especially for conditions influenced by kidney health. Surgical interventions are necessary for correcting congenital defects or repairing portosystemic shunts. Ongoing monitoring through regular veterinary check-ups is important to assess effectiveness and adjust therapies.