Alfie - a pale, interesting, cute cat
Ellie Mardell MA VetMB DSAM (Feline Medicine) MRCVS
RCVS Specialist and Diplomate in Feline Medicine
Alfie, a male neutered domestic short hair, was only a year old when he presented to his primary vet
with a 2 day history of lethargy. When blood samples alarmingly revealed a packed cell volume
(PCV) of 6%, Alfie was referred straight to Chester Gates.
Alfie was quiet, although remarkably well considering the degree of anaemia. He was in good body
condition. The mucus membranes were white. Alfie was tachycardic with a bounding pulse and a
murmur (likely to be haemic). The lung fields sounded normal. Abdominal palpation was
unremarkable.
A full blood count confirmed severe normocytic normochromic anaemia, and a reticulocyte count
showed no evidence of a regenerative response from the bone marrow. The white cell count and
differential was normal. A Coomb’s test was weakly positive (1:8) Coagulation times were within
normal limits. ELISA screening tests for FeLV antigen and FIV antibodies were negative, and a
confirmatory FeLV PCR was also negative. PCRs for the haemoplasmas, (mycoplasma haemofelis,
haemominutum, and turicencis) were negative for all three species. Screening imaging was
performed and showed cardiomegaly, probably secondary to the increased cardiac output
demanded during chronic hypoxia due to anaemia. The lung fields were normal. Abdominal
ultrasound was unremarkable.
During initial investigations, Oxyglobin (still available at this time) was administered as emergency
treatment in the absence of an immediately available blood donor. Clinically there was a reasonable
response, as Alfie was brighter and the heart rate a little reduced. However the haemoglobin levels
remained unmeasureable in-house before and after the Oxyglobin. In view of this, a type-matched
whole blood transfusion was given the following day prior to anaesthesia. Fortunately blood typing
showed that Alfie was the more common feline blood Type, A, meaning improved donor availability.
Stilton, a staff cat, gave up the necessary donation without too much protest.
Alfie was anaesthetised for a bone marrow sample. The procedure went smoothly and he recovered
well despite an arrythmia during the anaesthesia, presumably secondary to prior myocardial
hypoxia. Bone marrow cytology (received promptly the next day thanks to the efficiency of CTDS
labs), demonstrated a normal myeloid series, and lymphocytes, but almost total absence of red cell
precursors consistent with probable pure red cell aplasia (PRCA). Histology of a bone marrow core
confirmed this.
Following the transfusion, Alfie was brighter again, the tachycardia had resolved and his pulse
quality had improved, and his appetite had returned. Treatment for the PRCA was commenced with
immunosuppressive doses of prednisolone, and cyclophopshamide 50mg once every 10 days
(corresponding to 150mg/m2 once a week). Doxycycline was also given as a precaution until the
haemoplasma PCRs proved negative.
Alfie was discharged the following day, and regular follow-up appointments and monitoring
haematology samples were performed at his primary vets. A week later the PCV was 13%, low, but
Alfie felt on top of the world given this was more than double what he had been coping with
previously. More importantly, there was now a regenerative response evident from the bone
marrow. Two week further down the line, the PCV was 30% indicating an excellent response to
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treatment. Now two years on, Alfie is bright and well, and apparently quite a handful to examine
according to his primary vet! Alfie’s treatment is ongoing although the steroid dose has been
weaned right down.
When investigating any anaemic patient, the degree of anaemia compared to the severity of the
clinical signs, is likely to give some indication of chronicity. Patients with a chronic, gradually
developing anaemia, show physiological adaptation such that they can remain outwardly normal
with much lower haemoglobin (Hb) concentration than a patient with the same Hb deficiency that
has developed rapidly. Long standing, severe anaemias tend to be non-regenerative, but occasional
patients with chronic low grade bleeding (e.g. from the gastrointestinal tract) will present with a
severe, regenerative anaemia, and a reticulocyte count is essential in all cases of significant anaemia
to evaluate for a regenerative response. A careful history is required as anaemia and other blood
dyscrasias have been associated with certain drugs and toxins. Screening imaging can be useful to
look for sites of blood loss, systemic diseases such as lymphoma, or other neoplasia.
Evaluation of bone marrow cytology and histology is often required in the investigation of nonregenerative anaemia. It may help to identify disorders such as myelo or erythrodysplasia, red cell
aplasia, aplastic anaemia, neoplasia, immune mediated red cell destruction occurring within the
marrow, meyelophthesis (such as aleukaemic leukaemia) and myelofibrosis. In cats, careful testing
for FeLV is mandatory for all forms of anaemia and bone marrow disorders. Latent or sequestered
FeLV infection within the bone marrow has been recognised to occasionally cause anaemia and
other blood dyscrasias.
PRCA is typically a disease of young FeLV negative cats. Bone marrow samples show almost a
complete absence of the red cell line, including the very early precursor cells. In the absence of
underlying conditions such as toxin exposure or renal disease, the condition is often primary and
immune mediated, and will respond to aggressive immunosuppressive therapy. Reported treatment
combinations include prednisolone/cyclosporine, and prednisolone/cyclophopshamide. The latter
used to be the more frequently used combination and has been the author’s choice in the past with
good long term results. More recently a case series of cats with PRCA and excellent response to
prednisolone/cyclosporine has been reported. A good response to treatment is not guaranteed,
most cases of PRCA that do respond usually take around 1-4 weeks to do so, but some may take
many weeks or even months. To avoid early relapse, dose reductions of medication are usually made
very gradually (e.g. reducing the prednisolone dose by 25% every 3-4 weeks). Many patients will
eventually come off treatment altogether, however relapse may then occur, fortunately often with a
good response again to “rescue” therapy.
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Alfie; a great example of when not to give up even in the face of a PCV of 6% !
Stilton, blood donor extraordinaire
Alfie’s bone marrow cytology: Reduced cell numbers, red cell line conspicuous by its absence (rare
rubriblasts only), normal myeloid series, lymphocytes, and a few megakaryocytes
References
1. Stokol T and Blue JT (1999) Pure red cell aplasia in cats: 9 cases 1989-1997) J Am Vet Med
Assoc 214 75-9
2. Viviano KR and Webb JL (2011) Clinical use of ciclosporin as an adjunctive therapy in the
management of feline idiopathic pure red cell aplasia J Feline Med Surg 13, 885-95
Acknowledgements
Grateful thanks to CTDS laboratories for providing pictures of Alfie’s bone marrow cytology.
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