Clinical findings and treatment
On admission, a clinical assessment of the horse found that despite having poor body condition ( BCS 4/9), the TPR values ​​were within normal limits, the mucous membranes were normal, and the submandibular lymph nodes were not enlarged. Hematological and biochemical parameters were also found to be completely normal. However the horse was extremely pruritic and presented with generalised “moth-eaten” alopecia, with scabs containing blood (Fig. 2) over some of the alopecic areas. The lesions were however superficial (Fig. 3 and 4). Additionally there was no skin efflorescence observable to indicate the pruritus was caused by a common skin disease. Skin smears and scrapings were performed and were positive for Pantoea agglomerans , Staphylococcus epidermidis , and aerobic spore-forming species. These pathogens were discounted as being the primary source of the pathology and interpreted as being a consequence of secondary infection. Additionally there was no evidence of ectoparasites or fungal infection present. After skin scraping samples were obtained, the horse was repeatedly bathed once a day with Vetericyn Foam Care medicated shampoo, combined with ketoconazole (Innovacyn Inc, California), but to no effect. The parasitologist who was asked to examine the horse strongly suspected hypersensitivity to the bite of Culicoides spp . 30 ml of Ancesol (Chlorphenamine maleate, 10 mg/ml, Richter Pharma AG, Austria) was administered IV for three days in a row, but also to no effect. Due to the tail rubbing and the suddenly slightly increased eosinophils (0.84x10ˆ9/l; RI 0.00-0.80x10ˆ9/l), a coprological examination was performed, which was highly positive for Strongylus spp . The horse was dewormed with a 5-day course of fenbendazole per os (Panacur; Intervet International BV, The Netherlands) and on the sixth day moxidectin with praziquantel (Equest pramox, Zoetis, Czech Republic) was applied PO for 600 kg of BW. For psychogenic pruritus, amitriptyline (Amitriptyline-Slovakofarma tbl flm 50x25 mg, Zentiva, as; The Netherlands) was administered twice a day at a dose of 1-2 mg/kg which had a mild calming effect lasting for a few hours after application, but the pruritus was still present. To reduce the pathological effects of stress and the medication administered, antiulcer therapy, 4 mg/kg of omeprazole (Peptizole, Norbrook, Ireland) PO SID was introduced. After the first week of the above-mentioned therapy, the pruritus was still intense and did not respond to the therapy. Due to suspicion of atopic dermatitis, prednisolone was administered for 10 days per os, initially at a dose of 0.1 mg/kg once a day, increasing to to 1.5 mg/kg twice a day, without effect. Topical therapy with mometasone-furoate (Elocom ung; Organon, The Netherlands) was applied only once to the lesions, however also without effect. Due to a secondary skin infection, the patient was bathed with a 4% chlorhexyderm shampoo (Clorexyderm, Industria Chimica Fine sri, Italy), which improved the pruritus only for a few hours, but subsequently worsened to the extent that the horse bit himself intensively and started to bleed from the self inflicted wounds around the coronary bands and groin (Fig 6 and 8). The distal limbs were subsequently bandaged to prevent further occurance. Sulfadiazine ointment (Ialugen, IBSA Group, Switzerland) was applied to the wounds for skin softening and laser was applied to promote healing. At this point there were also changes in the haematological examination; with an increase in WBC (14.36x10ˆ9/l; RI4.9-11.10x10ˆ9/l) and NEU (12.65x10ˆ9/l; RI 2.50-6.90 x10ˆ9/l).The secondary skin infection worsened and the body temperature increased in one evening to 39.6°C, however the pulse rate remained normal. Skin smears and scrapings were performed again and were positive for Bacillus spp .,Dermatophilus congolensis and Staphylococcus aureus.Mycological examination was positive for the species Alternaria spp . and Candida albicans . These findings were considered again to be secondary infection due to skin trauma, but at this time trimethoprim-sulfate (Norodine 45g; Norbrook, Ireland) PO BID for 7 days was started and the WBC and NEU returned to normal values. Serological tests were negative for Culicoides saliva hypersensitivity.
Because paraneoplastic pruritus was suspected, an ultrasonographic examination of the thorax and abdominal cavity was performed, but did not yield any pathological findings. Rectal examination was negative for a mass. Generally the horse continued to have an appetite, but on occasion was not interested in food especially during episodes of nervousness due to pruritus. On dental examination a few lesions around the incisors were observed as well as sharp edges on the premolars and molars, which were likely the cause of the erosions on the buccal mucosa. The lesions near the incisors were small and it is impossible to deduce if they could have been a clinical sign or if they arose as a consequence of self-mutilation and rubbing of the nose against the walls. After two weeks of hospitalization, the horse started to loose body condition to 3/9 BCS. During the third week, the hematological profile showed a decrease in lymphocytes (0.91x10ˆ9/l; RI 1.50-5.10 x10ˆ9/l) and monocytes (0.15x10ˆ9/l; RI 0.20-0.60x10ˆ9/l) and at the same time a slight swelling in the preputial area was noticed. At the end of the third week of hospitalization, the horse began to clinically deteriorate over the course of one evening. The horse became nervous, started kicking at the abdomen, and became aggressively pruritic. On clinical exam it was observed that the pulse rate had increased to 60 beats per minute, while the body temperature remained normal. Additionally the right submandibular lymph node become slightly oedematous, and the jugular veins were prominent. Hematological examination showed an increased hematocrit/ PCV (48) despite the intake of 30 liters of fluids per os and also a further decrease in lymphocytes (0.77 x10ˆ9/l; RI 1.50-5.10 x10ˆ9/l) and monocytes (0.10x10ˆ9/l; RI 0.20-0.60x10ˆ9/l). Biochemical blood analysis values remained normal. Blood lactate, haptoglobin, and SAA also stayed within normal values. Rectal examination showed mild dehydration of the large colon, otherwise there were no pathological findings. Ultrasonographic examination of the abdominal cavity revealed an increase in free fluid and a change on the ultrasonographic pattern of the spleen around ​​the gastrosplenic vein (Fig. 11). Ultrasonographic examination of the thoracic cavity showed massive pleural effusion and secondary compressive atelectasis of the lungs (Fig. 12). It was deduced that the increased heart rate was as a consequence of compensation for this condition. An ultrasonographic examination of the mediastinal nodes was attempted, but no mass was identified ultrasonographically. Thoracocentesis was performed bilaterally, due to a non-fenestrated mediastinum, from which 12 liters of serosanguinous fluid was drained from the thorax. The pulse rate did not however drop after drainage of the chest chavity or after analgesia was provided with flunixin 1.1 mg/kg IV (Flunixin, Norbrook, Ireland). The drained fluid was sent to the laboratory for analysis (Table 1). A cytological examination was concurrently performed as a tumour within the thoracic cavity was highly suspected. The sample contained large numbers of small lymphocytes with round nuclei and reduced cytoplasm. The findings of numerous poorly differentiated anaplastic cells with marked macrokaryolysis and numerous nuclei confirmed the presence of a lymphoblastic process. On the second day after thoracentesis, the patient developed a fever of 38.9 °C (the second time during hospitalization). The pulse rate increased to 74 beats per minute and anorexia was evident for the first time. A repeated ultrasonographic examination of the thorax confirmed a massive pleural effusion, and due to the poor prognosis, the horse was humanely euthanized and subjected to a post-mortem examination.