Hi Natalie,
Some great questions, treating cats is confusing with little or no evidence for very much!! I will answer each question in turn:
My understanding from the lectures is that all cats in congestive heart failure get frusemide at lowest effective dose.
Yes, that’s correct. We will cover this later in the CHF section. However, as a rule of thumb I use 2mg/kg PO BID (TID if they were difficult to control) and then once I am happy the cat is stable I will try and reduce the dose to lowest effective, although not really below 1mg/kg BID.
Those with evidence of smoke / spontaneous contrast on echo get clopidogrel to reduce risk of thrombus.
Yes, clopidogrel is the one we choose as we have evidence for its use from the FATCAT study (2015) in recurrent ATE events. So, I prescribe it to cats with moderate dilation of the LA, smoke, or poor LA systolic function.
Do you ever use aspirin in these cases?
Not really, no. the therapeutic index isn’t very high (its not COX selective) and I would prefer to use clopidogrel with rivaroxaban (a factor Xa inhibitor) or one or the other. I might use aspirin if the cat is very difficult to tablet though, as better than nothing probably (although we don’t know this either!).
I know a lot of clinicians use every third day (think it’s a quarter tablet?). Can this be given in combination with clopidogrel?
Yes, you can use it in combination with clopidogrel as they work in different ways.
You said there’s no good evidence that ACE inhibitors such as benazepril improve survival so we should not give these unless hypertensive?
I will use an ACE inhibitor if the cat isn’t doing very well, but the King paper suggests that including an ACE inhibitor has no benefit either before CHF develops or during CHF. I will use spironolactone though as there is a (poor) study that suggests some benefit, but what I really use it for is boosting the potassium levels.
And pimobendan is contraindicated unless it is DCM which is much rarer.
It’s not contraindicated per se, it is just that there is no evidence that it works. This makes sense as pimobendan increases contractility but HCM is a diastolic disease. a recent paper showed no benefit in using it in cats with HCM to 180 days, so it is going out of fashion. I would definitely use it in a cat with DCM though, or possibly end-stage HCM where you see poor systolic function secondary to myocardial ischaemia.
Then where I’m a little confused is – do you use beta blockers such as atenolol only in obstructive hypertrophic cases where there is systolic anterior motion, and then diltiazem in HCM cases without obstruction to improve diastolic filling? Or am I mixed up?
Yes, atenolol only in severe HOCM. Again, no benefit here but physiologically it makes sense to use a beta blocker. You need to demonstrate the severity of the obstruction via Doppler though before prescribing it. We don’t use diltiazem in cats, unless they have an arrhythmia. It used to be prescribed for HCM as the thought was that slowing the HR down would improve myocardial perfusion, but it is TID dosing and there is no evidence that it works.
Hope that clears things up for you 🙂
Liz
