Combined surgical and radiotherapy treatment of a mandibular ameloblastic carcinoma in a pony

A 9‐year‐old Welsh Section D gelding was referred to an equine hospital for evaluation and computed tomographic (CT) imaging of a left mandibular swelling. An expansile mass, found within the left mandible at the level of the caudal 2 cheek teeth, was surgically debulked and histology of the lesion identified it as an ameloblastic carcinoma. Radiotherapy using 4 fractions of 800 cGy, 7 days apart, was subsequently undertaken. The pony made excellent clinical progression following treatment. Repeat CT imaging at 7.5 and 19.5 months post surgery showed no apparent recurrence of the lesion and marked improvement in the remodelling of the mandible. In conclusion, radiotherapy in conjunction with surgical debulking appears to have been successful in treating an ameloblastic carcinoma in this pony and could be considered for similar tumours in other cases.     

Oesophageal obstruction in an aged pony associated with squamous cell carcinoma

An aged miniature pony was referred for chronic recurrent oesophageal obstruction. Endoscopic examination demonstrated distal oesophageal constriction and radiography confirmed an irregular soft tissue mass in the region of the distal intrathoracic oesophagus. The pony was subjected to euthanasia and post mortem examination confirmed squamous cell carcinoma of the distal oesophagus and stomach. Oesophageal squamous cell carcinoma is a rare condition in horses, but should be considered as a differential diagnosis in cases of chronic recurrent obstruction, particularly in older horses.     

Surgical treatment of a rostral mandibular complex odontoma in a 3‐year‐old horse

Complex odontomas are rare odontogenic tumours in horses comprised of a combination of mesenchymal and epithelial tissues. Examination, radiographic and histopathological findings in this patient all represent the typical behaviour of a complex odontoma. Oral tumours in horses may have treatment limitations due to tumour size and location. Similar to treatment in other species, surgical enucleation was curative for this type of tumour.     

Surgical treatment of synovial osteochondromatosis in the middle carpal joint of a pony

A 9‐year‐old Paint pony gelding presented for signs of left carpal swelling of 1–2 weeks' duration. Radiographic, ultrasonographic and arthroscopic evaluation of the left carpus was consistent with synovial osteochondromatosis. This presumptive clinical diagnosis was confirmed histopathologically. Arthroscopic removal of the osteochondral bodies resulted in resolution of the carpal effusion and return to previous athletic activity by 4.5 months post operatively. Arthroscopic removal of osteochondral bodies is the treatment of choice in cases of suspected synovial osteochondromatosis.     

Rostral mandibulectomy for treatment of a sarcoma in a 16-year-old Thoroughbred mare

A 16-year-old Thoroughbred mare presented with a 1-year history of a growing mass on the rostral mandible. Biopsy performed by the referring veterinarian revealed chronic granulating fibrosis and stomatitis. Due to progressive loss of body condition and increasing size, the mare presented to the clinic. Radiographic examination of the mandible revealed osteolytic lesions. Mandibulectomy was performed under general anaesthesia. The horse's demeanour and feed intake improved significantly and the cosmetic outcome was acceptable. Histopathological examination confirmed a sarcoma, most likely a fibrosarcoma.     

Surgical management of a pony with a traumatic medial luxation of the patella

This report describes a successful surgical repair of medial patellar luxation in a Miniature Shetland pony where manual reduction of the patella was not possible. The surgical procedure involves transection of the medial femoropatellar ligament to facilitate patellar release, the placement of a prosthetic suture to replace the lateral femoropatellar ligament and reinforcement of the lateral retinaculum by the use of a mesh implant. This is a newly described surgical technique for the rare but recognised condition of a medial luxation of the patella.     

Surgical treatment of paraphimosis in a pony

Circumcision (or reefing operation) was performed on an aged pony stallion to remove excessive granulation tissue involving the preputial integument following an injury and subsequent paraphimosis. Postoperative swelling of the penis and prepuce was reduced daily with gentle massage. Initially, an improvised suspensory was used to support the penis postoperatively. The pony was able to voluntarily retract its penis six months following surgery.     

Complex mammary carcinoma with metastases to lymph nodes,subcutaneous tissue,and multiple joints in a dog

An 8‐year‐old, intact female, mixed‐breed dog presented to the Oklahoma State University Boren Veterinary Medical Teaching Hospital for evaluation of progressive lameness and joint effusion of multiple joints. Physical examination revealed joint effusion of the elbow, hock, and stifle joints bilaterally, enlarged left axillary and right popliteal lymph nodes, a subcutaneous mass over the left elbow, and a subcutaneous mass involving the left second and third mammary glands. Cytologic examination of the mammary mass, enlarged lymph nodes, and joint fluid from most affected joints revealed a monomorphic population of loosely cohesive neoplastic epithelial cells. The patient was humanely euthanized, and subsequent necropsy with histopathologic examination revealed a complex mammary carcinoma with metastases to enlarged lymph nodes, subcutaneous tissue over the left elbow, and the synovium of multiple joints. Immunohistochemical stains were performed and showed diffusely positive pan cytokeratin, CK8/18, and CK19 staining in the neoplastic luminal epithelial cells of the mammary carcinoma, synovium, and lymph nodes, and showed diffusely positive vimentin staining of the myoepithelial cells. Myoepithelial calponin positivity was diffuse in the mammary mass and lymph nodes but minimal in the synovium. Only the mammary mass showed p63 positivity. Metastatic mammary neoplasia is relatively common in dogs; however, metastasis to the synovium has only been reported once previously in the literature. This is the first case utilizing immunohistochemistry for confirmation and characterization of metastases.     

Surgical resection of a dysgerminoma in a mare

A mare was referred for further evaluation of a mass found in the left caudal abdomen during a routine postpartum reproductive palpation. The mare was clinically normal with no history of health problems. Ultrasonographic examination of the mass confirmed its presence, but the origin of the mass could not be accurately determined. Routine haematology and serum biochemistry results were within normal limits. The mare was initially treated conservatively with antibiotics, but the mass continued to increase in size, so it was surgically excised. The mass involved the left ovary. The mare showed transient abdominal pain after surgery, but developed no other complications and was in foal 7 months later. On histology, the mass was diagnosed as a dysgerminoma, a rare ovarian tumour of germ cell origin.     

Long-term outcome of treatment of a squamous cell carcinoma of the foot by amputation of the distal limb in a pony

This report describes a rare case of squamous cell carcinoma (SCC) in a 10-year-old Shetland pony. The pony was presented for evaluation of a chronic, ulcerating mass of the foot associated with a nonweightbearing lameness of the right forelimb. Foot radiographs revealed an aggressive bone lesion with severe osteolysis of the distal phalanx. Amputation of the digit was performed under general anaesthesia at the level of the metacarpophalangeal joint using a palmar flap technique and a transfixation cast for protection of the stump. Avascular necrosis, infection and dehiscence of the stump occurred 3 weeks later and a second amputation was performed at the level of the proximal third of the third metacarpal bone. Histopathology revealed a squamous cell carcinoma. After healing of the stump, a prosthesis was fitted to the limb for improved ambulation of the pony. Two years after the amputation, telephone follow-up with the referring veterinarian and the owner, revealed that the pony was healthy and able to go out daily in a paddock with its prosthesis. SCC represents an unusual indication for limb amputation. Successful outcome is rarely reported in horses.     

Surgical treatment of a large congenital cavernous haemangioma on the thorax of a foal

A 3‐day‐old male foal was presented with a fluctuant 25 × 15 cm mass on the thorax. The mass had increased in size since birth. The mass did not respond to conservative treatment consisting of aspiration of serohaemorrhagic contents and compression bandages, and it was therefore surgically removed when the foal was approximately 2½ weeks. A histopathological diagnosis of cavernous haemangioma was made. Healing progressed without complications despite a large surgical wound left to heal by second intention. Recurrence was not observed during the 1.5‐year follow‐up period.     

Surgical reconstruction of a severely comminuted mandibular fracture in a horse

A Palomino gelding presented for evaluation of a mandibular fracture and physical examination revealed swelling and excoriation of the skin over the ventral mandible. Upon further examination, malalignment of the incisors was appreciated in addition to instability and crepitance of both the rostral aspect and vertical ramus of the mandible. Radiographic examination revealed a comminuted fracture within the interdental space and fractures of both vertical ramii of the mandible. Under general anaesthesia via tracheotomy intubation, the fractures of the vertical ramii were reduced and compression plating techniques used along the caudal‐lateral border of both ramii for stabilisation. Intraoral tension band wires were used for repair of the interdental space fracture. A type II external skeletal fixator using Steinmann pins and polymethyl methacrylate connecting bars was applied to increase stability. The horse was maintained on broad spectrum antibiotics and phenylbutazone and discharged following 6 days of hospitalisation. Radiographs were taken 10 weeks after surgery and revealed evidence of adequate healing. On follow‐up 20 months later, the horse was reported to have no difficulties eating and was maintaining its bodyweight. This case is unique due to the severity of the mandibular fracture. The authors are unaware of any previous reports of such a severely comminuted mandibular fracture and its successful reconstruction employing multiple surgical techniques.     

Diagnosis,treatment and outcome of spinal lymphoma in a pony

This report describes the diagnostic approach to, and treatment of, a case of severe pelvic limb ataxia in a Miniature Shetland pony. Diagnosis of an intradural‐extramedullary lesion at the level of T11–12 was made using CT myelography. Dorsolateral hemilaminectomy allowed surgical debulking of an intradural mass, diagnosed histopathologically as T cell rich B cell lymphoma. Post operative treatment with prednisolone, cytarabine and cyclophosphamide was tolerated well and the degree of ataxia reduced markedly, allowing the pony to return to normal management.     

Ultrasound as a diagnostic tool in the investigation of a pony with intestinal lymphoma

A 21‐year‐old New Forest pony presented for evaluation of lethargy and colic. Transcutaneous abdominal ultrasonography revealed a cavitary, thick walled, mass‐like lesion that appeared continuous with the small intestine. The thick walls of the mass‐like lesion were of heterogeneous echogenicity with hyperechoic foci extending from the hyperechoic luminal surface to within the wall and there was loss of normal wall layering. These findings were confirmed grossly at exploratory celiotomy and histopathological examination of affected tissues confirmed lymphoma. The ultrasound findings facilitated a preoperative presumptive diagnosis that allowed informed decision‐making and aided case management.     

Posterior lens luxation with associated glaucoma in a pony

Secondary lens luxation is an infrequent consequence of equine recurrent uveitis (ERU). This Case Report describes a pony with posterior lens luxation with associated glaucoma, thought to be secondary to ERU.     

Severe hypophosphataemia associated with the management of hyperlipaemia in a miniature pony

This report describes a case of severe hypophosphataemia associated with the management of hyperlipaemia in a miniature pony following colic surgery. Clinical signs attributed to hypophosphataemia included obtundation, anorexia, tachycardia, tachypnoea and generalised muscle fasciculations. Hyperlipaemia was managed with enteral and partial parenteral nutrition; insulin was also administered to control hyperglycaemia after the initiation of caloric support. Specific therapy for hypophosphataemia consisted of parenteral potassium phosphate at 0.03 mmol/kg bwt/h (i.v.). The pony made a full recovery without further complications. Hypophosphataemia may be an under‐recognised clinical problem in certain populations of critically ill equids, such as those with hyperlipaemia and receiving insulin as part of their management. The routine measurement of phosphate concentration in these cases is recommended.     

Surgical treatment of mammary carcinomas in dogs with or without postoperative chemotherapy

This retrospective study identified prognostic factors associated with survival; and compared survival data in 94 canine mammary carcinoma (MCA) dogs treated with surgery (n = 58), or surgery and adjunct chemotherapy (n = 36), and a subset of dogs with poor prognostic factors. On multivariate analysis independent predictors of median survival time (MST) were clinical stage, lymphatic invasion (LI; present 179 days; none 1098 days), ulceration (present 118 days; none 443 days) and surgical margins (incomplete 70 days; complete 872 days). Complete surgical margins were associated with MST in dogs with stages 1–3 MCA (incomplete 68 days; complete 1098 days) and dogs with LI (incomplete 70 days; complete 347 days). There was no statistically significant improvement in MST in dogs with advanced disease (stage 4 or LI) treated with adjunctive chemotherapy (chemotherapy 228 days; none 194 days); although five dogs with complete surgical margins that received mitoxantrone and carboplatin had a mean survival of 1139 days.     

Mandibular squamous cell carcinoma in a young horse

Squamous cell carcinoma (SCC) is a frequently reported neoplasm in the horse. However, oral forms are uncommon and represent only 7% of all SCC. A literature review reveals a total of 13 cases of oral SCC with no apparent sex or breed predisposition but predominantly adult and old horses, mean age 16.5 years. This case report describes a 3.5-year-old pony filly that was presented for investigation of a mandibular fistula of 3 weeks' duration. The clinical and histopathological findings of mandibular squamous cell carcinoma in this filly are described in detail.     

Metabolic changes associated with anaesthesia and cherry poisoning in a pony

Observations  A case of a pony with severe cyanide intoxication as a result of cherry ingestion is presented. General anaesthesia was performed for colic surgery. Severe metabolic lactate acidosis in combination with a high arterial oxygen partial pressure and clinically good peripheral perfusion parameters were the remarkable signs during anaesthesia. Severe hypothermia was obvious during recovery. Ten hours post-surgery the pony was euthanized as a result of neurological signs. The diagnosis of cyanide intoxication was made post-mortem.
Conclusion  Cherry ingestion can lead to lethal cyanide intoxication in horses indicated by severe nonhypoxic lactic acidosis during anaesthesia.