Ulcerative Dermatitis, Thrombocytopenia, and Neutropenia in Neonatal Foals

Abstract

This report describes transient ulcerative dermatitis, severe thrombocytopenia, and mild neutropenia in 6 foals from 4 mares from geographically diverse regions of the United States. The foals presented at Ͻ4 days of age with oral and lingual ulcers, and crusting and erythema around the eyes, muzzle, and perineal, inguinal, axillary, trunk, and neck regions. There was a severe thrombocytopenia (0-30,000 platelets/L), leukopenia (1,200 white blood cells/L), and mild neutropenia (500-1,800 neutrophils/ L). Four of the 6 foals had petechiae and ecchymotic hemorrhages and 3 had bleeding tendencies. Results of examination of a bone marrow biopsy from 1 foal were normal and results of a platelet surface immunoglobulin test in another were negative. Histopathology of the skin in all foals showed subepidermal clefting with subjacent vascular dilation, dermal hemorrhage, and superficial papillary necrosis. The foals were treated supportively with broad-spectrum antibiotics (5/6), corticosteroids (3/6), gastric ulcer prophylaxis (6/6), whole-blood transfusion (4/6), and platelet-rich plasma (1/6). The skin lesions and thrombocytopenia (Ͼ50,000 platelets/L) improved in 2 weeks (4/6). Two foals had a decline in their platelet counts when the steroids were decreased and needed protracted treatment. All foals survived and were healthy as yearlings. Two mares that had 2 affected foals each, upon subsequent pregnancies to different stallions, had healthy foals when an alternate source of colostrum was given. The findings in the cases in this report suggest a possible relationship between colostral antibodies or some other factor in the colostrum and the thrombocytopenia and skin lesions, although further investigation is warranted to confirm or refute this hypothesis.Key words: Dermatopathy; Horse; Neutrophil; Platelet; Skin.T he purpose of this paper is to describe a syndrome of transient ulcerative dermatitis, severe thrombocytopenia with bleeding tendencies, and neutropenia in neonatal foals. The physical examination, clinicopathologic, clinical progress, and histopathology of skin biopsy findings of 6 neonatal foals from geographically diverse regions of the United States will be presented. Materials and MethodsThe medical records of 6 neonatal foals examined between 1998 and 2002 with a transient ulcerative dermatitis and severe thrombocytopenia were summarized. The foals were seen at 3 referral hospitals throughout the United States, including Cornell University Hospital for Animals, Ithaca, NY (n ϭ 2), Washington State University Veterinary Teaching Hospital, Pullman, WA (n ϭ 2), and Peterson and Smith Equine Hospital, Ocala, FL (n ϭ 2). A CBC and skin biopsy were performed on all foals. The skin biopsies were fixed in formalin and the slides were evaluated by 1 dermatologist (WHM) retrospectively for the purposes of publication. Data collected from the record included the signalment and parity of the mare and events (medications, illness, and vaccinations) that occurred during pregnancy and parturition, the health of t...

Equine platelet concentrate preparation and validation

“…Regardless of the exact number, thrombocytopenic horses are significantly more likely to die or to be euthanized than are horses with normal platelet counts, highlighting the clinical importance of thrombocytopenia of any degree. Five of 6 neonatal foals with ulcerative dermatitis, thrombocytopenia, and neutropenia syndrome were treated with whole blood or platelet‐rich plasma (PRP) transfusions due to life‐threatening thrombocytopenia …”

Anti-inflammatory Drugs in Equine Neonatal Medicine. Part II: Corticosteroids

“…To the authors' knowledge, the pharmacokinetics and pharmacodynamics of dexamethasone administered PO or IV have not been investigated in neonatal foals notwithstanding its large use in a variety of clinical settings [3][4][5][6][7][8][9].…”

“…Corticosteroid therapy results in a rapid increase in platelet counts in foals with alloimmune thrombocytopenia [8,9], probably by inhibiting destruction of antibodycoated platelets by tissue mononuclear phagocytes. As it is suggested by many equine neonatologists, corticosteroids should be used with caution in young foals because of the immune suppression associated with prolonged or high doses.…”

“…The same dosage was used to treat a presumed IMHA in two older foals with Rhodococcus equi infection [5]. The therapeutic goal should be to maintain a platelet count high enough to provide adequate hemostasis rather than increase the count to normal levels; thus, many affected foals may not require corticosteroid therapy [8,80].…”

“…Other conditions that are treated with corticosteroids are acute lung injury or acute respiratory distress syndrome (ALI or ARDS) in foals of few months of age [3] and immune-mediated hemolytic anemia (IMHA), which have been reported in both neonate [4] and older foals [5]. Corticosteroids have also been used in the treatment of neonatal isoerythrolysis (NI) [6,7] and in immune-mediated thrombocytopenia [8,9].…”