Transient leucopenia, thrombocytopenia and anaemia associated with severe acute phenobarbital intoxication in a dog

Abstract

A nine-year-old Labrador retriever dog was admitted to the emergency unit of the Hebrew University Veterinary Teaching Hospital with acute-onset tremors and coma. It had recently ingested a large quantity of phenobarbital and had a high serum phenobarbital concentration. On this basis, a diagnosis of acute phenobarbital intoxication was made. Significant leucopenia, thrombocytopenia and mild anaemia developed on the third day after admission. The leucopenia resolved on day 6 and the thrombocytopenia on day 13. The red blood cell count remained low for the next month. The dog was discharged on day 13 at which time it was ambulatory but weak. It was completely recovered clinically eight days later. In summary, high levels of serum phenobarbital as a result of acute intoxication induced pancytopenia, which improved when the serum phenobarbital level was normalised.

Drug-induced blood cell dyscrasia associated with phenobarbital administration in a dog

“…Previous reports have demonstrated that PB intoxication, accompanied by high PB levels, can induce pancytopenia [6]. However, PB can induce severe blood dyscrasia even at low dosages, as in the present case, where the PB level was even lower than the reference range (15-45 µg/mL).…”

“…The mechanism by which PB induces leukopenia, thrombocytopenia, and anemia as ADE of PB treatment has not been fully explained [6]. A previous report that evaluated the bone marrow of dogs with PB-induced pancytopenia showed the occurrence of myeloid hyperplasia [5].…”

“…No actual hepatocellular damage during PB treatment has been confirmed; however, PB administration can contribute to the induction of serum liver enzyme activities in dogs [2,8]. In addition, PB has infrequently been associated with hematologic adverse drug events (ADEs) in dogs, including reversible neutropenia, thrombocytopenia, and anemia [5,6]. Long term use of PB can also lead to bone marrow necrosis [13].…”

Epilepsy beyond seizures: a review of the impact of epilepsy and its comorbidities on health‐related quality of life in dogs

“…Phenobarbital treatment in dogs has been associated with idiosyncratic adverse drug reactions, including haematological abnormalities (phenobarbital-induced haematological abnormalities [PBIHA]) such as neutropenia, anaemia and thrombocytopenia (Jacobs and others 1998, Weiss and Smith 2002, Weiss 2005, Von Klopmann and others 2006, Vargo and others 2007, Khoutorsky and Bruchim 2008, Behne and Engelhardt 2010, Thrift and others 2010). The prevalence of these abnormalities is variable, with estimates of 4.2 to 22 per cent (Haböck and Pakozdy 2012, Bersan and others 2014).…”

International Veterinary Epilepsy Task Force consensus proposal: medical treatment of canine epilepsy in Europe

“…These effects occur uncommonly in dogs and include hepatotoxicity [ 13 , 22 , 39 , 75 ], haematologic abnormalities (anaemia, and/or thrombocytopenia, and/or neutropenia) [ 51 , 56 ]), superficial necrolytic dermatitis [ 66 ], potential risk for pancreatitis [ 38 , 46 ], dyskinesia [ 58 ], anxiety [ 58 ], and hypoalbuminaemia [ 41 ] (Table 1 ). Most of these idiosyncratic reactions are potentially reversible with discontinuation of PB.…”