Myofibroblastic fibrosarcoma with multifocal osseous metaplasia at the site of equine influenza vaccination.

We describe a fibrosarcoma in a 12-year-old Quarterhorse x Arabian gelding as a sequela to equine influenza vaccination. Shortly after the second vaccination, swelling at the site was noticed by the owner and it continued to increase in size over the following 6 months. Biopsy of the mass indicated a fibrosarcoma had developed at the vaccination site. It was approximately 20 cm in diameter and elevated well above the level of the skin. There was no clinical evidence of metastases to the lungs or local lymph nodes. Surgical resection of the mass was performed and the wound healed by first and second intention. Histopathological examination and immunohistochemical staining confirmed a myofibroblastic fibrosarcoma with multifocal osseous metaplasia. To the authors' knowledge, this is the first equine case of a vaccine-associated fibrosarcoma.

Management of equine skull fractures using fixation with polydioxanone sutures.

Ten horses presented with severe distortion of the facial contour, crepitus on palpation and mild to moderate epistaxis. Individual horses also showed ocular damage, ptosis, severe dyspnoea and movement of the facial bones concurrent with respiration. The fracture fragments were exposed using a large curvilinear incision and elevated using a retractor, periosteal elevator, chisel or Steinmann pin. The fracture fragments were unstable following reduction and fixation was necessary. Stabilisation was achieved with polydioxanone sutures placed through holes drilled in opposing sides of the fracture lines. Polydioxanone sutures provided good stability and had better handling properties than wire. There was good apposition of fracture edges and minimal complications. Use of polydioxanone sutures can also avoid the expense and complexity of plate fixation in selected cases, and should be considered as an alternative to fixation with stainless steel wire in any facial fracture that adjoins stable bone.

Calcified tumours of the paranasal sinuses in three horses.

Three horses, a 10-year-old Thoroughbred mare, a 9-year-old Thoroughbred gelding and a 6-year-old Arab gelding, with calcified tumours of the paranasal sinuses, are described. All horses presented with purulent nasal discharges and facial distortion. Exophthalmos, blepharospasm and ocular discharge were also a feature in individual horses. A presumptive diagnosis of a calcified tumour was made on the basis of clinical signs and radiographic and endoscopic findings. The tumours ranged from 15 to 25 cm in diameter. A large frontonasal bone flap was used to expose the tumours, which were cleaved into several pieces with an osteotome and removed. Histological examination of the masses identified cementomas in two cases and an osteoma in the third. Long term follow up from 18 months to 5 years after surgery indicated that there was no recurrence. This case series demonstrates that, although calcified tumours of the paranasal sinuses are rare in horses, they should be considered in the differential diagnosis of purulent nasal discharge, facial swelling and ocular distortion, and are amenable to surgical treatment.

Placement of a long term tracheal cannula in a Thoroughbred racehorse with bilateral laryngeal dysfunction.

A Thoroughbred horse with bilateral laryngeal dysfunction was treated by placement of a long term tracheal cannula in order to restore full athletic function. The horse initially presented with right-sided arytenoid dysfunction that was considered to be due to a congenital malformation of the laryngeal cartilage. This was corrected by a right-sided laryngoplasty and ventriculectomy. The horse re-presented 1 year later with idiopathic left laryngeal hemiplegia. The decision was made to place a long-term tracheal cannula due to the low success rate and high complication rate associated with other surgeries used to correct bilateral arytenoid dysfunction. A three-piece tracheotomy cannula and stopper were positioned under general anaesthesia. The horse rapidly adjusted to the tracheal cannula and no post-surgical complications were encountered. The horse resumed training 4 weeks postoperatively. Due to the rules governing racing in Australia the horse was exported to New Zealand where he continued his racing career. It was concluded that tracheotomy is a straightforward technique associated with minimal complications and can provide an excellent prognosis for return of full airway function in racing horses. It is recognised that many issues need to be considered prior to more general acceptance of this technique, including assessment of animal welfare issues and public perception. In appropriate cases consideration should be given to using long term placement of a tracheotomy cannula as a treatment option to restore maximal airflow in horses with upper airway obstruction.

Surgical treatment of extensive chondroid formation in the guttural pouch of a Warmblood horse.

A Warmblood horse presented with a purulent nasal discharge that had failed to respond to antibiotic therapy. Radiography and endoscopy confirmed a large number of chondroid masses (over 200) in the left guttural pouch. Despite the large number of chondroids present, there was no external swelling evident. The masses were surgically removed via a hyovertebrotomy approach that provided excellent exposure, and no postoperative complications were encountered. Long term follow-up (3 years) confirmed a successful outcome.

Exercise physiology. An overview.

Through the study of equine exercise physiology, one can learn more about what happens to the body of the performance horse during all forms of exercise. Better understanding of skeletal, joint, tendon, and ligament adaptations to loading and stress may allow adjustments to be made in training techniques to reduce the incidence of injury. The information obtained from exercise research may also facilitate the investigation of questions such as the following: What makes one horse perform better than another? How can one bring out the optimal performance in each horse? How can one tell when a horse has arrived at its peak performance capability? What are the factors that actually limit performance?

A protracted case of cryptococcal nasal granuloma in a stallion.

A 13-year-old Standardbred stallion presented with a unilateral mucopurulent nasal discharge and airway obstruction was found to have an extensive cryptococcal nasal granuloma. Treatment was not attempted. The stallion was destroyed 26 months later having completed 2 successful breeding seasons. The granuloma had gradually increased in size and almost completely occupied the left nasal cavity and paranasal sinuses. It was characterised histologically by fibrous and myxomatous tissue and masses of yeasts. A cryptococcal granuloma found within the wall of the jejunum could represent evidence of dissemination, and organisms were seen within alveoli, bronchioles and the intestinal lumen.

The anorexic and actometric effects of cocaine and two coca extracts.

The effects of cocaine and two extracts of the coca leaf were compared using locomotor activity and limited access food consumption paradigms. The three treatments were tested using both IP and PO routes of administration. The extracts were prepared by first extracting the powdered leaves with 95% ethanol, evaporating the ethanol and then partitioning the residue between water and chloroform. The doses of the extracts studied were 60, 120, 240, and 480 mg/kg. The doses of cocaine studied were 3.45, 6.9, 13.8 and 27.6 mg/kg. These doses corresponded to the amount of cocaine contained in the four doses of the chloroform layer. Cocaine and the chloroform layer (via both routes) produced dose related increases in locomotor activity and dose related decreases in food consumption. The water layer (containing only trace amounts of cocaine) produced no changes in locomotor activity; however, the highest IP dose did significantly reduce food consumption. Furthermore two of the doses (one IP, one PO) of the chloroform layer produced significantly greater effects than an equivalent amount of cocaine. These data suggest that plant constitutents other than cocaine may contribute to the overall effect achieved by chewing the leaf.

Effects of d-amphetamine and diazepam on paired and grouped primate food competition.

Two male and two female rhesus monkeys (Macaca mulatta) were the subjects of an experiment designed to assess the effect of d-amphetamine (DA; 0.125, 0.5 and 2.0 mg/kg, IM) and diazepam (DZP; 0.5 and 2.5 mg/kg, IM) on food-getting behavior in paired and group competition. Paired competition results show that in some cases submissive animals, that had previously failed to obtain apple pieces, were successful in obtaining some apple pieces when either the dominant animal of the pair or both subjects were given 0.5 mg/kg DA or 2.5 mg/kg DZP. Results revealed the same effect when all animals (group competition) were given 0.125 and 2.0 mg/kg DA and 2.5 mg/kg DZP. These results appear to indicate that the effect of drugs on food-getting behavior in competitive situations is in some manner influenced by the social status of the animal.