Page 11 - VetCPD Jnl Volume 7, Issue 4

VETcpd - Cardiology
Brigite Pedro
DVM MSc DipECVIM-CA (Cardiology) MRCVS
Willows Veterinary Centre and Referral Service Brigite.pedro@willows.uk.net
Brigite graduated
in 2008 from the University of Porto, in Portugal. In 2012 she started a three-year residency in Veterinary Cardiology at
the University of Liverpool. In 2014 Brigite completed a Masters degree
in cardiovascular pathophysiology.
In 2016 Brigite joined the cardiology team at Willows. She is currently doing a PhD in atrial fibrillation in dogs.
João Neves DVM MRCVS
Willows Veterinary Centre and Referral Service Joao.neves@willows.uk.net
João graduated
in 2009 from Oporto University, Portugal. He moved to the UK in 2013 to undertake a cardiology internship at the
University of Liverpool, followed by
a general internship at Dick White Referrals. In 2014, he started a residency in Small Animal Cardiology at the University of Liverpool. After completion of his residency, João was promoted to Lecturer. He then joined the Willows team in 2018.
Chris Linney
BVSc GPCertSAP CertAVP(VC) DipECVIM-CA (Cardiology) MRCVS
Willows Veterinary Centre and Referral Service Chris.linney@willows.uk.net
Chris graduated with Honours from the University of Liverpool in 2007. In 2009 he returned as an Intern in small animal studies, followed by a three
year residency in Cardiology. He was subsequently promoted to the position of Lecturer in Cardiology. He has worked at Willows since 2015 and
is the clinical lead and Head of the Cardiology team.
Peer Reviewed
Atrial Fibrillation in Dogs: Treatment and Monitoring
Atrial fibrillation (AF) is the most common cardiac arrhythmia seen in dogs. It can occur in any condition where there is significant atrial stretch, with mitral valve disease and dilated cardiomyopathy being the top two causes. Atrial fibrillation typically indicates that there is advanced and marked underlying cardiac chamber dilation but it is occasionally seen in the absence of cardiomegaly, the so called “lone” AF. Atrial fibrillation is a rapid and disorganised discharge of electrical activity from the atria with a variable ventricular response rate, which results in the erratic and irregular rhythm. Where the AF heart rate is fast and/or where there is a low cardiac output, dogs will be symptomatic and AF management is indicated. Rate control is the initial treatment of choice where there is underlying heart disease; based on recent retrospective studies, good control of AF with an improved survival and prognosis may require rate control to <125bpm. In addition to medical management, electrical DC cardioversion may be an option for some dogs which can revert them back to a sinus rhythm; this requires no or minimal structural heart disease for the greatest chance of success. AF can be managed readily in general practice and good quality of life can be expected.
Key words: arrhythmia, canine, heart, rhythm, rate
Introduction
Atrial fibrillation (AF) is the most common non- physiological arrhythmia in dogs (Bonagura 1986; Noszczyk-Nowak et al. 2017). It has a significant
impact on morbidity and mortality, therefore it is important for the clinician to be able to identify and treat this arrhythmia appropriately.
Epidemiology
In dogs,AF is more common in males; adult to old dogs are most commonly affected, mainly because of the higher prevalence of underlying cardiac diseases in that population (Bonagura 1986; Westling et al. 2008; Jung et al. 2016; Noszczyk-Nowak et al. 2017; Pedro et al. 2018), which is frequently seen in association with this arrhythmia.
Any breed can be affected by AF, however large and giant breed dogs are overrepresented, particularly Dogue de Bordeaux, Great Dane, Newfoundland, Mastiff, Irish Wolfhound, German Shepherd, Rottweiler, Labrador Retriever and Australian Shepherd (Menaut et al. 2005; Jung et al. 2016;Vollmar and Fox 2016; Pedro et al. 2018).
Considering these breeds, it is not surprising to see an association between AF and dilated cardiomyopathy (DCM).
In fact, up to 50 % of dogs with DCM have been reported to also be affected
by AF (Martin et al. 2010;Ward et al. 2019). However, dogs with myxomatous degenerative valvular disease (MDVD) can also develop this arrhythmia: a recent study showed that AF was detected in 52% of dogs with MDVD and congestive heart failure (CHF) weighing over 15 kg (Jung et al. 2016), while dogs weighing over 20 kg have a 5.8 times higher chance than smaller breed dogs of developing the arrhythmia (Borgarelli et al. 2006).
Pathophysiology
Frequently AF presents in two different scenarios:
Lone or Primary AF
In some cases,AF is detected in animals without an obvious underlying structural heart disease.This is the so called “lone” or primary AF. In these cases, the atria appear within normal dimensions (as
no obvious remodelling is noted on echocardiography), although histopatho- logical analysis has revealed subclinical cardiomyopathies and atrial fibrosis in Irish Wolfhounds (Vollmar and Aupperle 2016), a breed where a genetic compo- nent also appears to play an important role (Fousse et al. 2019). Furthermore, it has been reported that IrishWolfhounds diagnosed with primary AF had higher chances of developing DCM than those
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