This week we continue discussing heart disease in pets, now looking at what your vet will be checking for when they examine them.
A thorough cardio-thoracic (heart and lungs) physical examination will often give your vet a lot of information, including whether or not further investigation is required. The clinical signs you have witnessed and report will also provide valuable clues to determining the severity and likely cause of the condition.
The first thing your vet may look at is the colour of your pet’s gums or inner eyelids, checking for pallor or, in extreme cases, a bluish tinge. They are likely also to push on the gum so it blanches to see how fast blood returns to the area (known as capillary refill time). If it takes longer than expected, it may indicate that blood is not being distributed as normal by the heart or circulation.
The blood vessels may be examined next, starting with the big vein in the neck, the jugular, in which they are looking for distension or pulsation. In addition, the femoral artery (felt high up on the inner thigh) is often palpated on both sides. It can either be made stronger or weaker depending on the nature of the heart problem and, in certain conditions, you get one pulse strong the next one weak, or even where the quality of the pulse varies with the breaths in and out.
Auscultation of the heart (listening to it) with a stethoscope is a big part of the examination. The normal heart rate in dogs is 70-150 beats per minute and in cats is 150-200 but as well as the heart rate factors such as how loud the heart is, whether there is any abnormality in the rhythm (known as an arrhythmia) or if there are any additional sounds or murmurs are just as important.
The femoral artery may be palpated in conjunction with listening to the heart to make sure there is a pulse felt for every beat. The normal rhythm and sound of the heart is the classic “lub-dub” repeated evenly. In dogs you can also get something called a sinus arrhythmia which can occur in a normal heart. With this you hear the heart rate increasing on inspiration and decreasing on expiration. A murmur is usually heard as a kind of whoosing noise over the top of the heart sounds. The position in which the murmur is loudest (which side of the chest as well as where on the chest wall), how long it lasts, how loud it is, whether you can feel it radiate and how far externally, and when the murmur occurs in relation to the lub-dub are all important to note. Some murmurs are only present under stress or can be present or disappear under anaesthetic, for example.
All these factors allow the vet to try to start localising which part of the heart is involved and how serious the condition is. Most murmurs occur when the heart is contracting (systole) which will be heard between the lub and dub making the heart sound now whoosh-dub.
The lungs will also be listened to with the respiratory rate (normal being 20-30 breaths per minute for dogs and 20-40 for cats) and amount of effort required observed. With a stethoscope, sounds such as crackles and wheezes may be heard in the lungs and again the location they are picked up will help with diagnosis and selecting appropriate treatment and investigative tests.
Next week we continue looking at hearts, moving on to how heart disease is further investigated and discussing the most common conditions seen.