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Tackling Small Animal Cardiology Cases

By Jane Pigott BVMBVS CertAVP(VC) MRCVS | June 25th, 2020

It is estimated that approximately 10% of dogs and 15% of cats presenting to first opinion practice will have cardiac disease of some form.

You therefore have a great opportunity to have a positive clinical impact on many of your patients by picking up on these potential cardiology cases and taking some initial steps toward diagnosis and treatment with the aim of improving their long term survival and quality of life.

My favourite thing about the heart is that it is very logical and it generally reads the rule book. If you approach heart cases with an air of calm and give yourself time to think about what you find, it won’t be long before you’re pointing in the right direction.

Tip #1 Spend time taking a thorough history

With these cases, a thorough history from the owner is vital. It’s the small things that give the big clues – for example: does the dog walk really calmly next to the owner now whereas he used to tear off all over the shop? Exercise intolerance is rarely a dog grinding to a halt on a walk, its usually far more subtle.

Key areas to cover in taking a cardiac history include:

  • Signalment – breed predilections can be a helpful clue
  • Onset of signs – chronic versus acute deterioration
  • Dyspnoea or tachypnoea
  • Presence and character of a cough
  • General demeanour at home – lethargy, appetite etc.
  • Presence of exercise intolerance
  • Detailed description of any weakness or collapse episodes (watch any videos if the owner has them)

Try to get a sense at this early stage of whether the owner is willing and able to medicate their pet at home – this will have a massive impact on decision making later.  Spending this time building a solid working relationship with your owner now will pay dividends later if your cardiac patient requires treatment.

Tip # 2 Assess the respiratory rate and effort before you touch the patient.

Although in-clinic respiratory rates are never the most accurate (sleeping respiratory rates in the home environment are best), they will be a lot more accurate before you start examining the patient and potentially causing any stress than at the middle or end of your exam. With cats, open the door of the cat box and peek in to take a respiratory rate before you take them out.

Tip #3 Palpate the apex beat prior to auscultation.

Palpate the precordium by placing your hands over the heart on each side of the chest. Use the most distal part of your palm (over your metacarpophalangeal joints) and fingertips as these are generally the most sensitive areas of the hands for this purpose.

Feel for the apex beat:

  • Is it normal, pronounced or reduced/absent? A reduced or absent apex beat might suggest the presence of a pleural or pericardial effusion, reduced myocardial contractility or be associated with a generous body condition score.
  • Is there a precordial thrill? If so, expect a loud murmur.

This information gained prior to auscultation can help to put what you hear later into context – essentially it gives you a few clues about what you’re facing before you start to have a listen.

Tip #4 Create a good environment for auscultation

Give yourself a fighting chance of picking up murmurs or arrhythmias and appreciating the subtleties of pulmonary auscultation by optimising your environment. If things are noisy in the consult room, taking a patient out the back to have a listen in a quiet place can help enormously, and has the happy side effect that you have some peace and quiet away from the owner to process what you’ve found and make a plan of action for the patient.

Purring cats usually stop purring if you put a water tap running nearby.

Atrial Fibrilllation is characterised on physical examination by a chaotic rhythm on auscultation with frequent pulse deficits. Characteristic findings on ECG include an absence of p waves and irregular R-R intervals.

 

Tip #5 Keep it simple when auscultating the heart

If you do not know what all the differentials for a pansystolic or holosystolic or crescendo-decrescendo murmur are, don’t worry. This stuff is not important in my opinion in the early stages of your career. Those nuances can develop later.

Focus on the big questions:

  • Can I hear the heart?
    • Yes – great.
    • No or the heartbeat sounds dulled – is there something in the way like a pleural or pericardial effusion, a mass, or the chest wall of an extremely obese patient?
  • What is the heart rate?
  • If there is a murmur:
    • Is it systolic, diastolic or continuous?
    • Is it loudest on the left or the right?
    • Is it loudest at the base or the apex?
    • Is it soft, moderate or loud? If possible, grade the murmur on the 1-6 scale, but this is not essential.
  • Are there any diastolic gallop sounds?
  • Is the heart beat regular, irregular (chaotic beats or tripping in the rhythm), or regularly irregular (i.e. likely respiratory sinus arrhythmia)?
  • Is there a femoral pulse for every heartbeat?

With a full cardio-respiratory examination including a thorough auscultation, you can go a long way toward narrowing down your differential list and deciding on what diagnostic steps might be required. Try to do a full cardiac exam in every patient if you can – we need to calibrate what ‘normal’ looks, feels and sounds like in our minds. This way, the abnormalities will become more obvious in contrast and you will learn to trust your ears when something does not sound right.

Tip #6 Look for Sinus Arrhythmia in your physical exam

If the dog has a respiratory sinus arrhythmia (i.e. heart rate increases during inspiration and then decreases during expiration in a cyclical fashion), it highly unlikely to have congestive heart failure. A respiratory sinus arrhythmia can be a normal clinical finding in dogs and signifies normal or high vagal tone.

Alterations in both sympathetic and parasympathetic tone associated with advancing cardiac disease lead to loss of a respiratory sinus arrhythmia, hence the predominant underlying rhythm usually observed in patients with congestive heart failure is sinus rhythm (i.e. regular R-R intervals that do not change with respiration), although arrhythmias such as atrial fibrillation or ventricular premature complexes may also be noted in these cases depending on the underlying pathology.

In contrast, a sinus arrhythmia is an abnormal finding in a cat in an in-clinic environment.

Tip #7 Cats are not small dogs

Cats are not small dogs when it comes to cardiology – be aware of the various species differences in both the normal findings and disease processes.

Tip #8 Take good quality radiographs, but be realistic about what can be achieved in each case.

  • Try to get good inspiratory views if xray is indicated – this will make assessment for oedema and cardiomegaly much easier. Obtain right lateral and dorso-ventral views for chests (but remember to take the DV first to avoid atelectasis).
  • If judged safe and possible in the case, lightly sedate the patient if you can. The resulting images will be of superior diagnostic quality and this is best practice under ALARA principles.
  • Put a wedge under the sternum and draw the forelimbs well forward. – it can make a big difference to the quality of your lateral view.
  • If your patient is dyspnoeic and won’t tolerate being in lateral for xrays, then don’t push it – a perfect right lateral xray is not worth causing patient deterioration for. In these cases, consider an alternative diagnostic modality, for example lung ultrasound to assess for the presence of numerous B lines etc.

Do your best to get images of diagnostic quality, but be pragmatic about what is possible in each particular situation. For cats that are too stressed to be handled for xrays, put them in a metal wire cat carrier, with the plate inside the carrier under the cat. Take your xray in this manner with the cat just sitting on the plate, with the lid of the carrier left open. These views will be far from perfect, but are a good initial step for basic assessment of the chest for pulmonary oedema or pleural effusion without causing your patient to get stressed and further decompensate.

Severly compromised dyspnoic patiens need careful handling during diagnostic investigations to avoid further deterioration. In cats, initial radiography may be achieved by allowing the patient to sit on top of the radiographic plate whilst placed inside a wire cage. The exposure is taken in this way with the lid of the cage remaining open, and the patient minimally stressed.

Tip #9 Don’t be afraid to take a hands-off approach with dyspnoeic cardiac emergency cases.

Perform a basic triage examination, give them oxygen, careful sedation, any medication you feel is essential to improve the situation and then give them space to relax. Watch them and then proceed carefully once they have calmed down a little. This is especially important with cats, as they can easily be pushed over the edge in these situations.

For yourself, panic on your part in these cases is also futile – cardiac emergencies can be stressful to begin with, but you still need to be able to think clearly and proceed calmly. Try to take a breath and remain calm, take things slowly with the patient and remember that providing oxygen is never a wrong first step.

Tip #10 Don’t be afraid to ask for help

You don’t need to have all the answers with cardiac cases as a new grad. All you need to recognise is that ‘something is not right with this heart’. Give yourself time to think logically and formulate an initial diagnostic plan based on your physical exam. This may include asking for help or an opinion from a more experienced vet in your practice or advice from your local cardiologist. Referral for additional work-up may be indicated in many cases in order to make a firm diagnosis and to optimise the treatment plan, as many cardiac diseases require additional modalities including echocardiography or ECG/holter monitoring for a firm diagnosis.

Jane graduated from the University of Nottingham in 2014. Following 2 years in general mixed and small animal practice in both Ireland and the UK, Jane undertook a Small Animal Rotating Internship at the Small Animal Teaching Hospital, University of Liverpool. This was followed by a Cardiology Internship in Willows Veterinary Centre and Referral Service, where she developed a particular interest in congenital cardiac disease and interventional cardiology. Jane was awarded the RCVS Certificate in Advance Veterinary Practice in Veterinary Cardiology in Spring 2019 and became an RCVS Advanced Practitioner in Veterinary Cardiology in Spring 2020.  Jane is currently undertaking a Masters in Interventional Cardiovascular Medicine at the National University of Ireland, Galway to further develop her interest in cardiac device development for use in dogs.  Jane returned home to practice in north Cork and is now a partner in Millstreet Veterinary Group. She offers a cardiology referral service through the recently launched Flow Veterinary Referrals Ireland, an independent referral service based in Millstreet, Co.Cork. Jane is always happy to discuss any cardiology cases should you need informal advice or support. You can contact her via email – flowreferrals@gmail.com. 

To keep up to date with the interesting cases at Flow Referrals you can follow them on Instagram here. 

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