Cardiovascular diseases are pathologies that affect the heart and the blood vessels (veins, arteries or capillaries). Similarly to the humans, the incidence of these diseases has also been increasing in animals, as a result of the rise in life expectancy due to the advances in medicine.
The majority of cardiovascular diseases in dogs and cats are the result of old age, usually attributed to the natural aging of the heart and the blood vessels, but it can also be caused by injuries and infections. Examples include myocardial disease (weakening of the heart muscle), cardiac arrhythmias or valvular problems (characterised by the deterioration of the heart valves, preventing them to close properly). Nevertheless, cardiovascular diseases can also have a genetic origin. These are rare and tend to affect mainly younger individuals, often leading to further health issues and increased susceptibility to other diseases.
Furthermore, the prevalence of these pathologies are not the same for all species. For instance, certain animals are resistant to a diet-induced blood vessel disease called atherosclerosis, characterised by the narrowing or blockade of arteries as a result of the buildup of fat, cholesterol or calcium. This shows the importance of the genetic component in some of these diseases. Similarly, the prevalence of some congenital heart malformations is also different between species. For example, it is known that the blood pressure is higher in giraffes and turkeys than in other species. Also some irregularities in the heart beating are normal and harmless in dogs, horses and moles but can have serious consequences in other animals. Moreover, incidences can also vary betwen breeds. For example, certain breeds of pigeons suffer from a higher incidence of atherosclerosis than others. Equally, some congenital heart diseases are known to be more common in purebred dogs, such as Boxers, German Shepherds and male Cocker Spaniels.
As well as in humans, animals can also live with heart disease for long periods without showing any symptoms, so early diagnosis is essential to delay their onset. Symptoms can emerge either slowly or suddenly after intense exercise, and in some occasions can be fatal. Dogs and cats are susceptible to heart disease at any age, so it is important that the owners are alert to symptoms such as tiredness, intolerance to exercise, dry cough, shortness of breath, weight loss, abdominal bloating or loss of consciousness (fainting) caused by the lack of blood reaching the brain. More rarely, animals can also show swelling of their legs, jaundice (yellow eyes, skin or mucous membranes) or coughing sometimes accompanied by blood.
In addition to heart diseases, older animals are also be susceptible to pathologies affecting the blood vessels. For example, hypertension is a common problem in cats that suffer from hyperthyroidism or kidney disease and can lead to the formation of blood clots potentially resulting in cerebral ischemia, usually referred as stroke. Stroke happens when there is a disruption in blood supply to parts of the brain. This can lead to a variety of symptoms depending on the area of the brain affected as well as the severity of the incident. As well as in humans, animals can suffer from two types of stroke: ischemic (caused by reduced blood supply) or hemorrhagic (caused by accumulation of blood). Ischemic stroke occurs when a clot of blood or other material is lodged in a vessel, blocking the blood from reaching certain areas of the brain and leading to cell death. Hemorrhagic stroke is less common and occurs when a vessel ruptures, normally as a result of trauma or disease, damaging the cells due to excess blood inside the skull. The symptoms of stroke in pets are usually sudden but can vary depending on the location and the severity. It is therefore important for the owner to be alert to symptoms such as inability to move, incoordination, head tilt, abnormal eye movements, blindness, convulsions, loss of consciousness or behavioural changes.
In summary, the prevention of cardiovascular diseases is of paramount importance. Healthy eating and regular exercise are key to keep the animal in good physical condition. Furthermore, it is important that the owners are aware and attentive to any symptomatology the animal may present in order to allow an early detection and prevent problems that may arise, enabling a happier and healthier life.
by Ricardo Ribas, PhD
Veterinary doctor, doctorate in veterinary sciences and researcher in the area of oncology
The subjects and opinions discussed on this article are for informational purposes only. For more information consult your vet or a professional in the area.