Immune-mediated haemolytic anaemia in the dog

IMHA can often be a simple condition to diagnose, but treatment in both the short-term and long-term can bemo re problematical. The following case details some of the common dilemmas in dealing with IMHA.

HISTORY

A 7 y Mn Border Collie initially presented to his own vets in August 2007 with sudden onset lethargy and pallor. His PCV was initially 14%, strongly regenerative anaemia, which was Coombs positive. Screening radiographs failed to show any evidence of underlying disease, routine biochemistry showed mild increases in liver enzymes. Treatment with prednisolone 2mg/kg BID was initiated and when his PCV dropped to 11% azathioprine was added 2mg/kg SID. Over the following 2 months Toby's PCV slowly increased to 34%, but then started to decrease again. Danazol was added and Toby was referred.

EXAMINATION

On examination Toby was severely Cushingoid, with marked muscle atrophy, muscle weakness, hepatomegaly, thin skin and with a non-healing pressure sore over his right ischium. He had a marked plantigrade stance and could only stand for short periods. He was tachycardic, pale with hyperkinetic femoral pulses.

INVESTIGATIONS

Routine haematology showed PCV was 21%, with spherocytosis, suggesting poor control of his disease. His anaemia appeared moderately regenerative. Abdominal ultrasonography confirmed hepatomegaly, no other abnormalities were detected. Biochemistry confirmed changes consistent with a marked steroid hepatopathy, with bile acids >100umol/l. Clotting times were within normal limits. A swab of Toby's non-healing wound showed no evidence of MRSA.

Despite the poor response to high doses of steroids and immunosuppressives it was felt necessary to reduce his steroid dose, to allow wound healing and start to ameliorate the severe Cushingoid signs. Over 3 days his steroid dose was halved to 1mg/kg BID. He was started on 20mg/kg potentiated Amoxycillin. The azathioprine was stopped, because of it's potential myelosuppressive effects, the Danazol was stopped due to its potential hepatotoxic side-effects. Cyclosporin (Neoral) was started at 5mg/kg SID. When his PCV dropped to 15% 4 days after admission it was decided to transfuse Toby with 1 unit DEA 1.1 negative packed red blood cells, to improve his oxygenation. This brought about a immediate improvement in his demeanour and he was able to walk for short periods. His PCV increased to 23%. After 7 days cyclosporin levels were found to be subtherapeutic and the dose increased to 5mg/kg BID. Over the following 3 weeks Toby's PCV steadily increased, his steroid dose was further reduced to 0.5mg/kg BID when his PCV normalised. Four months after referral, he remains on prednisolone 0.5mg SID and 5mg/kg cyclosporin SID, his PCV remains well in the normal range (PCV 43%). Although still pot-bellied with poor hair re-growth Toby is very much brighter in himself. Further dose reductions will be implemented in the coming months and it is hoped that Toby can be weaned off all medication eventually.