IMHA (AIHM) - using cyclophosphamide or azathioprine

Re: IMHA (AIHM) - using cyclophosphamide or azathioprine

Toby Birch — Wed, 10 Feb 2010 01:34:13 GMT

Always an interesting topic.

Pred is generally the mainstay drug at 2-4mg/kg SID (hopefully tapering over many months). Often used BID but the half-life is such that SID is fine. Also generally add omeprazole while the dose is high. The problem is however that response can take up to a week and without the crystal ball we have no way of knowing which dogs are not going to respond. There is definately an argument for starting azothiaprine early due to the delayed response time and the fact that it may be too late if you wait until the pred has not had the desired effect.

Cyclophosphamide used to be used but some studies have shown that it can actually worsen the prognosis and therefore should be avoided. That having been said certain well known experts in the USA report no problems and are still advocating its use.

As said above there are also other options and new products becomming available even if they are costly. Also do not forget that this disease is one where multiple blood transfusions may be required. Not as a treatment but as a management tool to try and buy time to allow the immunosuppresives to work.

Hope that helps.

Toby

Re: IMHA (AIHM) - using cyclophosphamide or azathioprine

Rob Loxley — Tue, 09 Feb 2010 21:03:01 GMT

[quote user="i am ed"]re: cyclophosphamide, I was a bit confused about using this as well. I read a proposal/discussion for using it on the clinical notes of dog from another practise. Perhaps it was a mistake.[/quote]

Did they mean cyclosporin (Atopica)?

Re: IMHA (AIHM) - using cyclophosphamide or azathioprine

Edward Jones — Tue, 09 Feb 2010 10:07:07 GMT

Thank you for your replies everyone.

re: cyclophosphamide, I was a bit confused about using this as well. I read a proposal/discussion for using it on the clinical notes of dog from another practise. Perhaps it was a mistake.

Personally I tend to lean toward the keep it simple (,stupid) approach, especially if the crisis is under control and you've got a bit of time on your side.

Re: IMHA (AIHM) - using cyclophosphamide or azathioprine

Fiona French — Mon, 08 Feb 2010 22:16:15 GMT

Cyclophosphamide has been used, but has not been shown to have any benefit and is not advised due to the side effects.

It is often sufficient to use pred alone (2-4mg/kg/day) and you should see a response in a few days, but as already mentioned, if the patient is not responding and you need to add in azothioprine, it can take several weeks for this to take effect! So I would use pred alone in less severe cases, and pred and azothioprine (1-2mg/kg SID or EOD) in the worse ones. Not sure about azothioprine, but with pred I would keep on the full dose for at least 4 weeks, then slowly start to taper dose, reducing every 2 weeks if all seems to be well. Apparently some cases seem to need pred for the rest of their lives, at a fairly low dose, but I have never had a case like this.

Another therapy for IMHA is human immunoglobulins. These work by blocking several of the mechanisms causing erythrocyte production, so are immunomodulatory rather than immunosupressive. They are very quick to take effect, and are great in patients that are fading before your eyes. It is given as a one off, IV in a similar manner to a blood transfusion. Only problem is the cost! You need to give 0.5 -2g/kg, and 5g costs around £400-£450! I have never used this, so don't know where to get it from.

By the way, I'm not an expert in this, but recently I saw an archived webinar from Idexx on the subject. Might be worth contacting Idexx to see if they will give you access to it, very useful.

Re: IMHA (AIHM) - using cyclophosphamide or azathioprine

Hanna Bennett — Mon, 08 Feb 2010 19:32:28 GMT

i tend to judge on severity of anaemia and clinical signs. the bad ones get preds and azathioprine from the outset, as said crsytal ball is never as clear as i like, and a week is a long time when a dog has a pcv of 15%!

never used cyyclophosphamide - this is cytotoxic and myelosuppressive so surely not appropriate. do you mean cyclosporin?

Re: IMHA (AIHM) - using cyclophosphamide or azathioprine

Laurence Webb — Mon, 08 Feb 2010 17:42:28 GMT

My understanding (based on CPD a couple of years ago so not bang up to date!) is that pred is generally the 1st line treatment. In refractory cases azothioprine is the next in line.

One down side of azothioprine is that is can take a week to have its effect, so you need to use your crystal ball to know whether the IMHA going to be refractory.

From the point of view of the cascade you should be using pred alone unless clinically indicated. I've tended only to use azothiprine in severe cases at the outset (belt and braces approach) then withdrawn it once under control or when unacceptable side effects of steroids are present. Generally I've found pred to work OK in its own though