Cutaneous blastomycosis in a horse

This report describes the case of a horse presented with cutaneous lesions caused by Blastomyces dermatitidis in the absence of signs of other organ involvement. Diagnosis was achieved through cytology, histopathology and culture. Surgical debulking associated with systemic therapy with oral fluconazole resulted in significant remission; however, recurrence occurred following presumed early cessation of treatment.     

Treatment of incisive bone fracture in a horse using an acrylic splint

A ventrally displaced incisive bone fracture was diagnosed in a 3-year-old Andalusian stallion. Symptoms included swelling of the lips, dysphagia and ptyalism. External manipulation revealed pain and crepitus in the gingival region of the rostral maxilla. An intraoral examination revealed upper gingival haematomas, misalignment and malocclusion of the incisors (prognathism). A radiograph of the rostral maxilla confirmed ventrally displaced bilateral fractures of the incisive portion of the maxilla rostral to the canine teeth (Triadan 104/204). The fracture was reduced under general anaesthesia. A methylmethacrylate intraoral splint was used to stabilise the fracture. Post operative radiographs confirmed the fracture reduction. Post operative clinical control confirmed the correct position of the splint. No complications were encountered in the post operative period and good stabilisation was obtained. The splint was removed 60 days post operatively. The use of an acrylic intraoral splint successfully stabilised a bilateral, ventrally displaced incisive bone fracture. Normal occlusion was obtained. The use of an acrylic splint may represent a relatively simple, inexpensive and noninvasive technique for the repair of incisive bone fractures rostral to canine teeth in horses.     

Treatment of appendicular osteosarcoma in a horse

A 14‐year‐old Arabian gelding was examined for a mass on the lateral aspect of the left tarsus and proximal lateral metatarsus. Radiography revealed a predominately osteolytic lesion involving the fourth tarsal bone and the proximal third and fourth metatarsal bone. Results of histopathological examination of the mass prior to surgery were consistent with an undifferentiated sarcoma. The mass was surgically excised and the remaining bone defect treated with absorbable beads containing cisplatin. Histology and immunohistochemistry of the mass removed at surgery revealed a telangiectatic osteosarcoma. The surgical site healed uneventfully and the horse was performing as a low level jumper 8.5 years after surgery.     

Cutaneous mucormycosis caused by Absidia corymbifera in a horse

A 5-year-old pregnant Spanish thoroughbred mare was presented with an extensive granulomatous lesion, of four months duration, on the left medial foreleg. On examination, the wound was covered by a large mass of ulcerated granulation tissue exuding thick serosanguinous fluid. The mare had not responded to previous treatment. Physical examination revealed no fever, no lameness and the presence of intense pruritus. A surgical resection was carried out to take samples for histopathology. On histopathologic examination the dermis and subcutaneous tissue showed large multifocal necrotic eosinophilic areas and inside these areas, irregularly ramified fungal hyphae. Microbiological examination showed abundant fungal growth and the strain corresponded to Absidia corymbifera . Treatment with amphotericin B was started but there was no improvement in the lesion. The mare aborted, became anorexic, had febrile episodes, had very poor body condition and was euthanized.     

Treatment of mycotic tracheitis in a horse with fluconazole and systemic iodine

Fungal infections of the equine trachea have been rarely reported. This case report describes the successful treatment of a mare with fungal infection of the trachea that had severe diffuse granulomatous thickening, erosions and haemorrhage of the proximal half of the trachea. The horse was treated with oral fluconazole and systemic iodine therapy. Serial endoscopic examinations confirmed rapid resolution of the condition.     

Treatment of a poorly differentiated sarcoma in the oropharynx of a horse

A 10-year-old Thoroughbred mare was referred to Tennessee Equine Hospital for evaluation and treatment of a subepiglottic mass. Physical and laboratory examinations revealed no other abnormalities. The tumour was excised through a laryngotomy site using transendoscopic laser and sharp excision. Histological evaluation revealed a poorly differentiated sarcoma with features of a leiomyosarcoma, a rarely identified neoplasm in the oropharynx of the horse. The mare developed intermittent dorsal displacement of the soft palate (iDDSP) after surgery but was able to resume full training. There was no evidence of regrowth 8 months post-operatively.     

Pyogranulomatous lesion causing neurological signs localised to the sacral region in a horse

This case report describes neurological signs associated with a pyogranulomatous lesion within the sacral vertebral canal of a horse. The clinical findings included urinary overflow incontinence and reduced anal, perianal and tail tone. The horse failed to respond to medical management and a guarded prognosis for return to athletic performance initiated the decision for euthanasia.     

Treatment of a subchondral cystic-like lesion in the distal scapula with a translesional bone screw in a horse

A 2-year-old French Warmblood stallion was presented for lameness investigation. The diagnostic procedures identified the reason for lameness as being a subchondral cystic-like lesion (SCL) in the glenoid cavity of the scapula. The horse was surgically treated with a translesional 4.5 mm cortical bone screw inserted through the SCL under radiographic guidance. Sixty days after surgery, the horse was sound and the SCL showed significant radiographic signs of healing. Radiographs obtained 180 days after surgery showed further radiographic healing, with the SCL presenting a radiodensity similar to the surrounding bone. At 4 years post-operative follow-up, the horse is sound and competing successfully as a 6-year-old in Concours de Saut International (CSI) competitions.     

Treatment of a metallic foreign body in the cranial cervical region of a horse

Ingestion of foreign bodies is uncommon in horses when compared with indiscriminate grazers such as cattle. This case report describes the diagnosis and treatment of a cervical abscess in a Thoroughbred racehorse thought to be associated with ingestion of wire. Radiographic and ultrasonographic examination provided a diagnosis, and conservative treatment of the lesion with antimicrobials initially allowed the lesion to localise closer to the skin for safer surgical exploration. Intra-operative ultrasonographic imaging facilitated surgical access, removal of the foreign body, and drainage. While surgical treatment is usually necessary to resolve an abscess, initially conservative therapy may help to improve the prognosis by simplifying surgical access and reducing the risk of surgical complications.     

Periocular neurofibrosarcoma in a horse

A periocular neurofibrosarcoma was debulked and treated with intralesional cisplatin in a 5-year-old Thoroughbred mare. The horse presented with a 1-year history of a large slowly progressing subcutaneous mass over the right supraorbital process. The mass was surgically debulked, and intralesional cisplatin (1.0 mg/cm3) was injected in 3 doses at 2 weeks, 5 weeks, and 8 weeks postoperatively. No recurrence was noted over a 15-month follow-up period. Histopathology of the mass indicated neurofibrosarcoma.     

Neurologic signs and hyperammonemia in a horse with colic

A 23-year-old Thoroughbred gelding was referred for the evaluation of acute onset of ataxia and depression, and a 2-day history of fever. On physical examination, the gelding was profoundly depressed and 10-12% dehydrated. The horse appeared very unstable, with a wide-based stance in the hind limbs, severe symmetric ataxia in all 4 limbs, and proprioceptive deficits in both hind limbs. Nasogastric intubation produced 4 L of brown, fetid reflux, and rectal examination revealed mild small intestinal and cecal distention. Hematologic abnormalities included neutropenia with toxic change, compatible with acute inflammation and endotoxemia, and prolonged coagulation times. Serum biochemical abnormalities included prerenal azotemia. metabolic acidosis, and electrolyte abnormalities consistent with enteritis. Blood ammonia concentration was markedly increased (406 micromol/L; reference interval 4-49 micromol/L), however, serum bile acids concentration and hepatic enzyme activities were within reference intervals. Histopathologic examination of a liver biopsy revealed no abnormalities and results of tests for several infectious agents were negative. Clinical signs resolved with correction of the dehydration and electrolyte abnormalities and with antibiotic therapy. The horse was diagnosed with hyperammonemic neuropathy associated with gastrointestinal disease. In such cases, hyperammonemia is caused by increased production of ammonia by organisms in the gastrointestinal tract in combination with increased gut permeability that facilitates ammonia absorption.     

Treatment and ophthalmic sequelae in a horse with facial cellulitis and orbital abscess

A 22‐year‐old Quarter Horse gelding with a history of dental (107) extraction 2 weeks previously was presented with facial cellulitis and an orbital abscess. The abscess was drained surgically dorsally and ventrally to the zygomatic arch and the horse was treated with parenteral antimicrobial and anti‐inflammatory drugs. The affected eye was protected with a temporary tarsorrhaphy and treated via a subpalpebral catheter. Six months after presentation, the horse was in excellent general condition and returned to previous level of exercise but showed blindness on the affected side. Pallor of the optic disc and severe attenuation of the retinal vessels, suggestive of optic disc atrophy, were present.     

Laparoscopic‐assisted splenectomy in a horse with splenomegaly

This reports describes the surgical management of a horse evaluated for recurrent colic. These frequent colic episodes were attributed by exclusion to an abnormally enlarged spleen (idiopathic splenomegaly). Splenectomy was elected and performed with a laparoscopic assisted technique. The advantages observed by using this surgical approach were a clear view of the visceral aspect of the spleen and consequently an accurate dissection of the hilus of the spleen and associated vasculature. Ultimately the laparoscopic technique allowed the surgeons to reduce the size of the laparotomy incision required to remove the spleen and the overall invasiveness of the procedure. The horse recovered well from the procedure and ultimately returned to the previous level of competitiveness.     

Renal cell carcinoma with bone metaplasia in a horse

A case of renal tubular carcinoma with bone metaplasia is reported in a 20-year-old male, mixed breed horse having a history of weight loss and hematuria. This report includes the clinical signs, macroscopic and microscopic lesions, and the immunohistochemical findings of this neoplasm.     

Surgical repair of a chronic,oronasal fistula in a horse using an alveolar bone flap

An 8‐year‐old Andalusian stallion was presented to the Equine Hospital with a 1.5 year history of an oronasal fistula measuring approximately 2 cm long (caudal to rostral) by 1.5 cm wide following an oral extraction of the right second maxillary premolar (106). An alveolar bone flap was created adjacent to the oronasal fistula and rotated axially and ventrally to close the oral aspect of the fistula. At 3 days after surgery, clinical signs of the fistula, such as green‐tinged purulent nasal discharge and malodorous breath, were no longer evident. At 10 days after surgery, the oral opening of the fistula filled with granulation tissue and mucosa and decreased in size to less than 2 ml. The horse was fed a pelleted mash and grass diet and the small fistula was flushed orally twice daily until it completely healed. At 6 months following surgery, the fistula had completely healed. Few options are available for repairing an oroantral or an oronasal fistula in horses. This case report suggests that a large, chronic oronasal fistula involving the alveolus of a maxillary second premolar can be repaired successfully with an alveolar bone flap.     

Bicavitary effusion in a horse with multicentric lymphoma

A 14-year-old Quarter Horse gelding presented for a 2-week history of increased respiratory rate, fever and weight loss. The referring veterinarian performed an ultrasonographic examination on the farm and considered a differential diagnosis of pleuritis and pleuropneumonia. On presentation, transtracheal wash showed suppurative septic inflammation with bacteria within macrophages. Thoracic ultrasonography showed increased hypoechoic fluid in the pleural and peritoneal cavities. Cytologic analysis of pleural and peritoneal fluids revealed lymphorrhagic effusion with atypical lymphocytes, suggestive of a lymphatic flow obstruction or lymphoma. Treatment consisted of drainage of the pleural fluid, anti-inflammatory agents, fluid therapy and antimicrobial therapy. Continued fluid accumulation in the thoracic cavity, tachypnoea, lack of response to pain medication and progressive lethargy resulted in the horse being subjected to euthanasia. At necropsy, bicavitary effusion was confirmed and histopathological diagnosis of multicentric lymphoma was made. Horses presenting with pleural effusion should also be evaluated for peritoneal effusion, as bicavitary effusion may indicate noninflammatory conditions such as neoplasia.     

Diarrhea and hyperammonemia in a horse with progressive neurologic signs

A 2-year-old, Quarter Horse filly was referred to Michigan State University, Veterinary Teaching Hospital with a 2-3 day history of depression and partial anorexia progressing to severe, watery diarrhea with severe neurologic abnormalities, including repetitive muscle fasciculations, muscle stiffening, and collapse. Laboratory findings included severe polycythemia, neutropenia, metabolic acidosis, and electrolyte and fluid loss, consistent with watery diarrhea and endotoxic shock. Increased creatine kinase and aspartate transaminase activities were consistent with recent transport and the muscle abnormalities. Severe hyperammonemia (1369.0 micromol/L; control value, 15.3 micromol/L) was found, without other substantial laboratory evidence of hepatic dysfunction. The horse was euthanized because of poor prognosis and rapid clinical deterioration. Necropsy findings were unremarkable with the exception of severe diffuse colitis. Culture of colonic contents recovered >1000 colony-forming units of Clostridium perfringens. Based on these findings, marked hyperammonemia in this filly was attributed to changes in colonic flora leading to increased bacterial production of ammonia that was readily absorbed through the inflamed bowel wall, exceeding the hepatic capacity for deamination. Intestinal bacteria as a source of hyperammonemia in the absence of hepatic disease has been linked rarely to positive culture results for clostridial organisms.     

Prolonged anesthesia using sevoflurane,remifentanil and dexmedetomidine in a horse

HistoryA 10–year old Arabian mare had a slow–growing mass on the lower right mandible and required a large partial mandibulectomy.Physical examinationNo abnormalities were detected apart from the mass.ManagementA temporary tracheostomy was performed pre–operatively. Anesthesia was induced with xylazine followed by ketamine and diazepam. For 13 hours, anesthesia was maintained using sevoflurane, dexmedetomidine and remifentanil infusions, with the exception of surgical preparation time. Intra–operatively, ventilation was delivered through the cuffed tracheotomy tube. Heart and respiratory rates, ECG, arterial pressures, inspired and expired gases, pulse oximetry values and body temperature were monitored. Dobutamine and whole blood were necessary, and romifidine was used to control recovery. Post–operatively, phenylbutazone and buprenorphine given systemically and bupivacaine administered through a wound soaker catheter were used to provide analgesia. Head–shaking from buprenorphine was controlled with acepromazine and detomidine once standing after 87 minutes in recovery. For 3 days after surgery, analgesia was provided with butorphanol, phenylbutazone and bupivacaine. The mare recovered well, appeared comfortable and started eating the following day with no signs of ileus.Follow–upSeven months later, the mare was doing well.ConclusionsSevoflurane, dexmedetomidine and remifentanil infusions were suitable for a long and invasive procedure.