Reply To: Anaemia

Great question.

I have made some comments under your text below. I did not want to miss anything!

A 13yo MN PWD presented for multiple diarrhoea episodes (5 within the same day) and lethargy. He is on long term meloxicam for management of OA. No other historical abnormalities noted. The diarrhoea contained. No melena or haematochezia and were judged to be a normal colour. His vet opted to run full CBC and Biochemistry. Clinical examination all wnl apart from pale pink mms.

So, I wonder whether there could be a degree of GI bleeding. The absence of melena does not rule out GI bleeding. In humans, it has been experimentally determined that at least 50 to 100 mL of blood must be ingested before melenic (is that a word?!) stool is appreciated. Normally with chronic GI bleeding the anaemia would ne microcytic and hypochromic. I would definitely consider a faecal occult blood in this patient.

We know the severity of the anaemia will influence the degree of response we get from the bone marrow. His anaemia is mild and so his response would also be mild. However 2 weeks down the line and he is still mildly anaemic (would expect an adequate response in 3-5d), he has never had a reticulocytosis.

I think that what you were seeing on the blood smear was quite appropriate for the degree of anaemia. You are right, the anaemia is mild. The 3-5 day mark is more relevant for haemolysis/bleeding. In the context of this case the anaemia is more likely to be due to chronic inflammatory disease. This could be the OA or even something diagnosed. Inflammatory cytokines suppress erythropoiesis, erythropoietin release, and response to erythropoietin, and sequester iron via hepcidin. This cytokine release will be ongoing and will be the reason you are not seeing the anaemia ‘bounce back’.

The question is in older dogs would we expect a reduction in an ability to respond to anaemia or do we investigate this dog further, for a cause? likely as a mild, non-regenerative anaemia?

This is a great question. This definitely a thing in people:

https://pubmed.ncbi.nlm.nih.gov/31230730/?from_term=anemia+response+with+ageing&from_pos=3

I cant find any evidence to say that this is something we worry about in dogs and cats. As with many things, our patients probably don’t live long enough to have some of the issues ageing people do. I would not worry about an anaemia of this degree if the dog is well. I would be looking for a focus of chronic inflammation if I was to investigate and would consider bone marrow biopsy if looking non-regenerative.

Hope that helps.

Scott 🙂