Arterial blood gas tensions during exercise in a horse with laryngeal hemiplegia, before and after corrective surgery.

Arterial blood samples were collected during maximal exercise over 1.6 km in a thoroughbred horse with left laryngeal hemiplegia. Acid-base and blood gas measurements were performed on each sample and compared to the results from samples which were similarly collected 48 hours after laryngoplasty surgery was performed. Before surgery, the PaO2 was 53.2 mm Hg and the PaCO2 was 58.1 mm Hg after 1.6 km. After surgery, the corresponding results were 83.6 mm Hg (PaO2) and 39.0 mm Hg (PaCO2). There was no significant difference in the times taken for each gallop. The exercise intolerance associated with laryngeal paralysis may be caused by an increase in the oxygen cost of breathing.

Radioimmunoassay for parathyroid hormone in equids.

Radioimmunoassay for parathyroid hormone (PTH) in equids was performed on blood samples from healthy equids and equids with hypercalcemia and hypophosphatemia. The assay was validated for equine carboxy-terminal PTH. Manipulation of serum ionized Ca in healthy equids by infusing Na2 EDTA and CaCl2 produced an expected increase and decrease, respectively, in measurable immunoreactive PTH. Intra-assay and interassay coefficients of variation were 2.6% and 11.7%, respectively. The range of PTH valves for healthy mature horse mares and geldings maintained on pasture was less than 0.27 ng/ml to 0.92 ng/ml and for horse colts fed grain was 0.61 to 1.25 ng/ml. Serum PTH values were measured on 2 equine patients with hypercalcemia, 1 pony with primary hyperparathyroidism and 1 horse with pseudohyperparathyroidism. Both patients had increased serum PTH values.

Use of a type II external skeletal fixator for repair of delayed union in three calves with forelimb fractures.

Three calves, 3 to 6 months old, were admitted for evaluation and treatment of fractures of the forelimb that had resulted from use of forced extraction at birth. Each of these calves had clinical and radiographic evidence of delayed union of a fractured metacarpus. All calves were treated, using a type II external skeletal fixator consisting of 0.25-inch-diameter transcortical pins and acrylic connecting bars. Two calves required open reduction of the fracture to obtain anatomic alignment of the limb. On the basis of the 3 calves described here, it would appear that type II external skeletal fixators may be adequate for treatment of selected calves with delayed union of a fracture.

Dystocia attributable to a fetal monster resembling schistosomus reflexus in a donkey.

A schistosomus reflexus fetal monster was removed from a jenny via cesarean section. This type of anomaly is seen principally in ruminants and swine. Only 3 cases have been reported in Equidae.

Cecal volvulus in a ewe.

Cecal volvulus in a ewe was diagnosed and surgically treated. Clinical signs were similar to those observed in cattle with cecal volvulus. Rectal palpation, which is an important diagnostic aid in cattle, was not possible in the ewe. Thus, the decision for surgery was based on clinical signs indicative of gastrointestinal obstruction, with the diagnosis of cecal volvulus being made at the time of surgery. Recovery after surgery was rapid, and follow-up evaluation at 13 months indicated no recurrence of the problem.

Congenital atresia of the parotid salivary duct in a 7-month-old quarter horse colt.

A 7-month-old Quarter Horse colt was examined because it had had a tortuous, distended vessel on the side of its head since birth. An abnormality of the parotid salivary duct was suspected on the basis of location and course of the vessel. Atresia of the duct near the parotid papilla was diagnosed by use of contrast sialography. Surgical transpositioning was attempted, but failed because of stricture formation. Chemical ablation of the salivary gland has been used to treat traumatic rupture of the duct. It proved to be an effective and practical method of resolving the problem in this case. Cosmetic outcome was excellent, and functional problems associated with loss of the gland were not observed.

Tarsal fractures in a heifer and a bull.

Tarsal fractures were diagnosed in a heifer and a bull. In both cases, radiography confirmed intra-articular fractures, with subluxation of the fracture fragment. Sudden, nonreducible hock flexion was a clinical sign in both cases. This sign may be highly suggestive of intra-articular fracture when diagnosis must be made without radiography.

Ultrasound-guided renal and hepatic biopsy techniques.

Diagnostic ultrasound is an easy, accurate method of locating both kidneys and liver in the horse. Good contact between the transducer and body wall is essential for clear, precise images. The greatest limitation to ultrasonic organ localization and biopsy guidance is the inability of ultrasound to transmit through gas-filled structures and bone. These structures act as barriers to sound-beam penetration and prevent visualization of soft-tissue structures deep to them. Organ parenchyma can be evaluated with ultrasonography. Focal and/or diffuse lesions can alter the normal parenchymal pattern and result in an increased or decreased echogenicity of the diseased area. Under ultrasound guidance, the biopsy instrument can be directed into these areas to insure that the sample is representative of the disease process within that organ. Biopsy-associated complications can be identified early and monitored until resolution. Equine renal and hepatic biopsies are not innocuous procedures, but ultrasonographic guidance has helped to reduce the risks involved with the biopsy techniques.

Ubiquitin expression in degenerating axons of equine cervical compressive myelopathy.

Neuropathologic examination revealed axonal swelling and breakdown leading to Wallerian degeneration of affected myelinated nerve fibers in the spinal cord white matter of four young horses with equine cervical compressive myelopathy. Immunohistochemical reactions for the cell stress protein ubiquitin revealed an enhanced presence in the swollen axons, which may reflect a role for ubiquitin in the neuronal catabolic process of axonal compression and degeneration in this myelopathy.

Excision of neoplasms of the bovine lower eyelid by H-blepharoplasty.

Neoplasms of the lower eyelid in 14 cattle were treated by wide surgical excision and H-blepharoplasty. Healing was by first intention, and cosmetic results were satisfactory in all cases. Lid function was satisfactory in 12 cattle, and there was no evidence of recurrence after at least 6 months in 12 cattle. This therapy can be recommended for large infiltrative masses on the lower lid if there is no evidence of bony involvement, metastasis, or involvement of both puncta at the medial canthus.

Efficacy of an epidural combination of morphine and detomidine in alleviating experimentally induced hindlimb lameness in horses.

Amphotericin B-induced synovitis of the left tarsocrural joint was used to create a grade 3 of 4 lameness in 11 horses. Caudal epidural catheters were placed and advanced to the lumbosacral region. Baseline heart and respiratory rates were recorded and horses were videotaped at a walk and trot. Morphine sulphate (0.2 mg/kg) and detomidine hydrochloride (30 micrograms/kg) were administered to treated horses (n = 8) through the epidural catheter; an equivalent volume of physiologic saline solution was administered to control horses (n = 3) through the catheter. At hourly intervals after epidural injection for a total of 6 hours, heart and respiratory rates were recorded, and horses were videotaped walking and trotting. At the end of the observation period, video recordings were scrambled onto a master videotape. Lamenesses were scored by three investigators unaware of group assignment or treatment time. Lameness scores, heart rates, and respiratory rates were compared between groups using repeated measures analysis of variance. There was a significant decrease in lameness score after treatment with epidural morphine and detomidine (P = .0003); average lameness scores of treated horses were less than grade 1 at each hourly observation for 6 hours after drug administration. Early in the observation period, heart rates significantly increased in control horses and decreased in treated horses (P = .03). A similar trend occurred for respiratory rates (P = .07). Results of this study demonstrate that epidural administration of a combination of morphine and detomidine is capable of providing profound hindlimb analgesia in horses.