Recanalized patent ductus arteriosus in the dog

In 140 consecutive operations for patent ductus arteriosus at the Michigan State University Veterinary Clinic over a period of 10 years, three animals have had recanalized defects (2 %), and of these, one dog recanalized for the second time. Of the 140 surgeries, fifteen were suture divisions and the remaining 125 were ligations. All recanalized cases had been ligated in the original operation. We believe, due to the ease of surgery, ligation is the preferred method. However, if the ductus recanalizes, division and suture should be accomplished in the second operation.     

Evaluation of Cervical Spinal Fusion as a Treatment in the Equine "Wobbler" Syndrome

Cervical vertebral interbody fusion was performed on 30 horses affected with cervical vertebral malformation (CVM) or "wobbles" to assess the efficacy of the surgery in either preventing progression of or reversing the neurologic deficit induced by the syndrome. Evaluation of each horse prior to surgery included clinical, radiographic, neurologic, and laboratory examination. Subjects ranged from 3 months to 8 years of age, and included 22 males and 8 females of various breeds. Three normal horses were included as controls. The Cloward method of cervical fusion was used to achieve stabilization at the affected vertebral articulation. Horses were reexamined 3 months after surgery. Clinical improvement was seen in 90% (27 of 30) of the cases. Four horses were returned to training, which had been interrupted by onset of symptoms. Seven were returned to owners as breeding animals. Twelve horses were kept for long-term studies. Seven horses were sacrificed to examine the surgical site. In 6 of the 7 horses on which necropsy was performed, the most severe histologic lesion in the spinal cord could be predicted from lesions seen radiographically. The spinal cords of control animals were normal. Osseous fusion was dependent on the completeness of removal of disc fibrocartilage during surgery. We conclude that clinical improvement in some horses affected with CVM can be achieved by cervical fusion.     

Intravenous fluid therapy for non-respiratory acidosis in dogs: a comparison of a balanced electrolyte solution with a fluid rich in potassium and bicarbonate

To assess the efficacy in dogs of an experimental solution (Solution A) containing high concentrations of bicarbonate and potassium, for the treatment of acidosis, acetazolamide was used to create a stable non-respiratory acidosis. A total of 24 dogs was used, being divided into two control groups and two groups receiving acetazolamide. One control group and a group receiving acetazolamide had a balanced electrolyte solution (Normosol R) administered at a flow rate of 38.2 ml/kg/h for 2 h, and the other control and acetazolamide groups received Solution A. Blood-gas, acid-base, electrolyte and various biochemical measurements, as well as arterial and central venous pressure measurements were performed before fluid administration and up to 24 h after administration.
Both fluids resulted in partial correction of the acidosis. Solution A returned acid-base balance closer to the values of control dogs by the end of 2 h of fluid administration than did Normosol R. Despite the high concentration of potassium in Solution A (20 mmol/1) there were only marginal elevations in plasma potassium values. Administration of an average of 80 mmol of bicarbonate to normal dogs resulted in an average increase of only 2.7 mmol/1, whereas in dogs with acidosis the increase was 6.4 mmol/1.     

Distribution of kanamycin in ocular tissues of calves

The ocular distribution of kanamycin following intramuscular, bulbar subconjunctival injection, or after constant rate intravenous infusion to calves was studied. Steady-state plasma concentrations of kanamycin were achieved in either normal calves, or in those experimentally infected with Moraxella bovis, and the concentrations of kanamycin in the serum, aqueous humor, vitreous body, tears, and the ocular tissues were measured. Kanamycin was not detected in the retina, lens, vitreous body, or the aqueous humor of any eyes, but the concentration of drug in the tears, conjunctiva, cornea and the orbital lacrimal gland of these calves ranged between 18 and 21% of that in serum. At steady-state plasma levels, the kanamycin concentrations in tears from eyes with keratoconjunctivitis and from normal eyes were similar. A study using lyophilized, powdered, ocular tissues in vitro showed that kanamycin was highly bound to the bovine retina and iris, and could be eluted using 0.2 N NaOH. The binding of kanamycin to other ocular tissues, including cornea, conjunctiva and lens, was significantly less. The concentration of kanamycin in the serum and the tears of calves was also measured after intramuscular or bulbar subconjunctival injection. After intramuscular administration of kanamycin (10 mg/kg of body-weight), the mean serum concentration was maximal at 1 h (32 micrograms/ml) and remained greater than or equal to 1.0 microgram/ml for 8 h. The mean tear concentration was maximal (3.1 micrograms/ml) at 30 min, and remained greater than or equal to 1.5 micrograms/ml for only 2.5 h. Following bulbar subjunctival administration of kanamycin (100 mg, single subconjunctival dose), the mean tear concentration was 1127 micrograms/ml at 30 min, less than or equal to 4.1 micrograms/ml at 4 h, and thereafter was less than or equal to 1.0 microgram/ml. It was concluded that kanamycin has limited distribution to the ocular tissues following parenteral administration. Binding of the drug to the ocular pigments may be responsible for its limited intraocular penetration.     

IMAGING DIAGNOSIS—INFILTRATIVE LIPOMA CAUSING SPINAL CORD COMPRESSION IN A DOG

An 11-year-old, 43 kg neutered female Labrador retriever dog developed acute pelvic limb paraparesis. In magnetic resonance images there was a T1- and T2-hyperintense extradural at the fifth thoracic intervertebral space that was causing marked compression of the spinal cord. In short tau inversion recovery and fat suppressed T1-weighted images the signal from the mass was decreased indicating it was of fatty origin. The mass was removed via a dorsal hemilaminectomy in the thoracic area. Histopathologic analysis confirmed the mass was an infiltrative lipoma. The dog recovered and is fully ambulatory 24 months after surgery. This report provides additional evidence that lipomas in the vertebral canal may be the source of pelvic limb neuropathy and also illustrates the value of magnetic resonance imaging in establishing the fatty nature of some soft tissue masses.     

DYNAMIC HELICAL COMPUTED TOMOGRAPHY OF THE PITUITARY GLAND IN HEALTHY DOGS

Dynamic helical computed tomography (CT) of the pituitary gland can be used to image the three-dimensional shape and dimensions of abnormalities within the pituitary gland. The aim of this study was to develop a protocol for dynamic helical CT of the pituitary gland in healthy dogs as a future reference study for patients with pituitary disease. Dynamic helical series of nine scans of the pituitary gland during and following contrast medium injection were performed in six healthy dogs using the following protocols: a series with 1 mm collimation and a table feed per X-ray tube rotation of 2 mm (pitch of 2) in six dogs, a series with 2 mm collimation and pitch of 2 in three dogs, and a series with 1 mm collimation and pitch of 1 in three other dogs. Multiplanar reconstructions of the images were made using a reconstruction index of 0.5. Images of all series were assessed visually for enhancement of the arteries, the neurohypophysis, and the adenohypophysis. The enhancement pattern of the neurohypophysis was distinguished adequately from that of the adenohypophysis in five dogs that were scanned with 1 mm collimation and pitch of 2, but the difference was less discernable when the other protocols were used. The carotid artery, its trifurcation, and the arterial cerebral circle were best visualized in dorsal reconstructions. Dynamic helical CT of the pituitary gland in healthy dogs can be performed with 1 mm collimation and pitch of 2, and a scan length that includes the entire pituitary region. Using this protocol, with the specific scanner used, the neurohypophysis, the adenohypophysis, and the surrounding vascular structures are adequately visualized.     

The use of yttrium oxide and the effect of faecal collection timing for determining the apparent digestibility of minerals and trace elements in Atlantic salmon (Salmo salar, L.) feeds

The effectiveness of the external marker yttrium oxide (Y₂O₃) and sampling period for determining the apparent digestibility (AD) of minerals and trace elements within Atlantic salmon feeds were compared. Yttrium oxide was compared at inclusions of 0.01, 0.1, 1 and 10 g kg^?1 wet weight of the feeds. Samples were analysed for a range of mineral and trace elements via inductively coupled plasma optical emission spectroscopy after wet decomposition with concentrated nitric acid. Feed marked with 1 g kg^?1 provided the greatest recovery, and provided analytical values within an optimal range, and therefore, the effect of faecal sampling period on AD of mineral and trace element was then compared using the feed marked with 1 g kg^?1 Y₂O₃. Faeces were collected over three different time periods within a 24 h period: 4 × 6 h, 2 × 12 h and 1 × 24 h. Magnesium, manganese, phosphorus, iron and chromium displayed significant differences in AD relating to sampling period. An inclusion level of 1 g kg^?1 Y₂O₃ and faecal sampling over at least an 18 h period after feeding proved to be the most effective method of determining AD of mineral and trace element in Atlantic salmon feed.