C-reactive protein (CRP), serum amyloid A (SAA) and α-1 acid glycoprotein (AGP) are APPs which increase in response to infection, traumatic, immunologic and neoplastic causes. The aims of this pilot study were to investigate whether these APPs could be used in dogs with primary bone marrow (BM) disorders to assist disease management.

Eight dogs with primary BM disorders were included in the study. Diagnosis was confirmed by BM biopsy in the absence of other diseases accounting for the cytopenias. Two dogs had BM neoplasia (BMN), 4 hypoplasia (BMH) and 2 dysplasia (BMD). Five dogs were untreated for at least 2 weeks prior to BM biopsy but 3 (2 with BMD and 1 BMH) received immunosuppressive therapy.

Serum samples were obtained from 7 out of 8 dogs at the time of referral and at subsequent intervals following instigation of treatment. In one dog APP monitoring was started 4 weeks post BM biopsy and 2 weeks after starting treatment while the animal was still severely anaemic and clinically symptomatic. Long term (>2 weeks) immunosuppressive therapy was given to 4 dogs (3 with BMH, 1 with BMD) and one dog with BMH also received lithium.

Twenty five samples were obtained from the 8 dogs (range of 1-9 samples per dog; mean of 3.1). Initial CRP concentration was above reference range in 6 dogs (1 with BMN, 3 with BMH and 2 with BMD); AGP was increased in 4 dogs (1 with BMN, 1 with BMH and 2 with BMD); and SAA was elevated in 2 dogs (1 with BMN, 1 with BMD).

Three of the 4 dogs that received treatment responded favourably. A negative correlation between CRP concentration, clinical improvement and a rise in PCV was observed. Moreover, the normalization in CRP concentration preceded the normalization in PCV. The dog that did not respond to immunosuppressants had BMH, with normal APP concentrations on presentation. Two weeks after starting treatment no clinical or haematological improvement was detected and euthanasia was performed at the owner's request. APP concentrations were still normal at this time.

These initial findings suggest APP concentrations may be elevated in primary BM diseases. Animals with BMH or BMD and elevated APP concentrations may benefit from immunosuppressant treatment if no other cause of their BM disorder is apparent. CRP appears more reliable than AGP and SAA.