Intraocular Foreign Body in a Dog

An unusual clinical case of panophthalmitis in the dog is discussed. Failure of resolution led to enucleation. Histopathology study showed an intraocular foreign body, probably a grass awn, that had migrated into the eye and established a panophthalmitis.     

Autonomic and Cardiovascular Effects of Neuromuscular Blockade Antagonism in the Dog

Autonomic and cardiovascular changes were studied when neuromuscular blockade was antagonized in 96 dogs with one of eight anticholinesterase-antimuscarinic drug combinations. Neostigmine (50 or 100 micrograms/kg) was administered before or after atropine (40 micrograms/kg) or glycopyrrolate (10 micrograms/kg). The high dose of neostigmine (100 micrograms/kg) caused bradyarrhythmias, salivation, and signs of bronchosecretion when used with either antimuscarinic agent and irrespective of the administration sequence. The heart rate increased, but not significantly, when atropine was injected before either dose of neostigmine. This did not occur when this administration sequence was reversed. Arrhythmias and cardiovascular and autonomic changes did not occur when glycopyrrolate was injected before or after neostigmine at 50 micrograms/kg.     

Effects of Xylazine and Ketamine on Epinephrine-lnduced Arrhythmia in the Dog

Ten dogs were studied to determine the effects of xylazine, ketamine, and xylazine combined with ketamine on the dosage of epinephrine required to produce ventricular arrhythmia. Untreated dogs required an arrhythmogenic dose (AD) of 5.88 +/- 2.85 micrograms/kg/min. The AD was 4.28 +/- 3.25 micrograms/kg/min in xylazine-treated dogs, 3.05 +/- 2.3 micrograms/kg/min in ketamine-treated dogs, and 2.96 +/- 1.95 micrograms/kg/min in xylazine/ketamine-treated dogs. The latter two dosages were significantly less than that of the controls (p less than 0.025). The duration of increased arrhythmogenicity was also examined. Four hours after drug administration, the AD for xylazine-treated dogs was decreased further to 3.87 +/- 2.52 micrograms/kg/min (p less than 0.05). Ketamine-treated dogs had returned partially to normal with an AD of 4.09 +/- 3.09 micrograms/kg/min, as had xylazine/ketamine-treated dogs, at 4.22 +/- 2.71 micrograms/kg/min.     

Effects of Acute Hyperventilation on Serum Potassium in the Dog

The effects of increasing respiratory rates on arterial pH, PaCO2, HCO3, and potassium (K) were measured in normal anesthetized dogs. Hyperventilation resulted in increased pH, decreased PaCO2, decreased HCO3, and decreased K compared with those parameters in spontaneously breathing dogs. The changes were related quantitatively: each 10 mmHg decrease in PaCO2 was associated with a pH increase of 0.1, a HCO3 decrease of 2.0 mEq/L, and a K decrease of 0.4 mEq/L. There were no cardiac arrhythmias or clinical signs of hypokalemia. After termination of hyperventilation, serum K was slower to return to control values than PaCO2. The ratio of the duration of hyperventilation to the time required for return of serum K to control was 0.67.     

The Cardiopulmonary Effects of Oxymorphone in Hypovolemic Dogs

Blood was withdrawn from 15 dogs over the course of about 1 hour until the mean arterial blood pressure was reduced to 60 mm Hg. Small aliquots of additional blood were withdrawn in order to maintain the mean arterial blood pressure near 60 mm Hg for an additional hour. Oxymorphone (0.4 mg/kg) was then administered intravenously to ten dogs, and all measurements were repeated in 5, 15, 30, and 60 minutes. Five dogs served as controls.
Heart rate, tidal volume, arterial oxygen, oxygen extraction, and pH significantly decreased after oxymorphone administration, while systemic and pulmonary arterial blood pressures, systemic vascular resistance (transiently), breathing rate, minute ventilation, physiologic dead space, venous admixture, venous oxygen, arterial and venous carbon dioxide, and bicarbonate concentration increased significantly. Cardiac output was also increased, but the change was not statistically significant. Oxymorphone was associated with significantly lower heart rate, tidal volume, arterial oxygen, and pH, and higher systemic and pulmonary arterial pressure, cardiac output, venous oxygen, and arterial and venous carbon dioxide, compared to the control group, which did not receive oxymorphone.
Oxymorphone significantly improved cardiovascular performance and tissue perfusion in these hypovolemic dogs. Oxymorphone did cause a significant increase in arterial carbon dioxide and a decrease in arterial oxygenation. Oxymorphone is an opioid agonist that may represent a reasonable alternative for the induction of anesthesia in patients who are candidates for induction hypotension.     

Effects of the Y-U Pyloroplasty on Gastric Emptying and Duodenogastric Reflux in the Dog

A Y-U pyloroplasty was performed on five healthy adult dogs. Gastric emptying half times (t1/2 GE) of a canned food meal were measured by scintigraphy three times before surgery and three times from 6 to 8 weeks after surgery. Fluoroscopic studies of gastric and duodenal motility were made before surgery and 3, 7, and 35 days after surgery. Clinical observations were made daily throughout the study. Gross and histologic evaluations of the gastroesophageal and pyloric regions were performed at the termination of the study. The t1/2 GE was significantly decreased after surgery. By positive contrast fluoroscopy, the vigor of antral contractions was seen to be decreased in three of the five dogs. On days 7 and 35, fluoroscopic findings were comparable to preoperative studies. Duodenogastric reflux was recognized fluoroscopically in three dogs on four different occasions. This may reflect normal reflux patterns in the dog. No gastrointestinal problems were evident after surgery in four dogs. Reflux esophagitis developed in one dog after surgery, which resolved with therapy. Studies of the Y-U pyloroplasty after 2 months indicated that it decreased gastric emptying time of solid food. Results of postmortem examination showed no abnormal gross or histopathologic changes of esophageal, gastric, or proximal duodenal tissues.     

Hemodynamic Effects of Medetomidine in the Dog: A Dose Titration Study

Objective —To characterize the hemodynamic effects of medetomidine administered intravenously at doses ranging from 1 to 20 μg/kg, and to determine whether these effects are dose dependent. Study Design —Prospective randomized multidose trial. Animals —Twenty-five clinically normal male beagles (5 groups of 5), aged 1 to 4 years and weighing 13.5 ±1.7 kg. Methods —Medetomidine, at a dose of 1, 2, 5, 10, or 20 μg/kg, was administered intravenously at time 0. Heart rate, arterial pressure, central venous pressure, mean pulmonary arterial pressure, pulmonary capillary wedge pressure, body temperature, cardiac output, and packed cell volume were measured immediately before and at selected times after medetomidine administration (3, 7, 10, 20, 30, 40, 50, and 60 minutes in all groups, at 90 minutes for the 10 and 20 μg/kg groups, and at 120 minutes for the highest dose). Cardiac index, stroke index, rate-pressure product, systemic vascular resistance index, pulmonary vascular resistance index, and left and right ventricular stroke work indices were calculated. The degree of sedation was subjectively scored by an observer who was blinded to the treatment used. Results —Heart rate, rate-pressure product, cardiac index, and left and right ventricular stroke work indices decreased below baseline values. Central venous pressure and systemic vascular resistance index increased above baseline measurements. Except in the 2 μg/kg group, after an initial and short lasting increase, a prolonged decrease in arterial pressure was observed. Conclusions —Hemodynamic changes were observed with the intravenous (IV) administration of medetomidine, at any dose. However, the two lowest doses (1 and 2 μg/kg) produced less cardiovascular depression. Clinical Relevance —Medetomidine is an alpha-2 adrenoceptor agonist widely used in dogs, producing sedation, analgesia and cardiovascular depression. When using IV medetomidine, a reduction of the recommended dosage (ie, ±30 to 40 μg/kg) by up to 6 times did not significantly influence the cardiovascular effects.     

Arthroscopy in the Dog

Veterinary Research Communications -     

Tonometry in the Dog and Cat

Abstract— A review is presented of the methods, procedure and value of the use of tonometry in the dog and cat.
Résumé— L'auteur passe en revue les méthodes, les techniques et la valeur de l'emploi de la tonométric chez le chien et le chat.
Zusammenfassung— Es wird eine Übersicht über die Methoden, das Verfahren und die Bedeutung der Tonometrie bie Hund und Katze gegeben.     

The Effects of Aortic Occlusion on Transcranially Induced Evoked Potentials in the Dog

Evoked potentials were produced by anodal stimulation over the motor cortex in six dogs. Potentials were recovered from the cranial thoracic and caudal lumbar portions of the spinal cord, and the radial and sciatic nerves. Evoked potential averages were recorded every 1.5 minutes during 40 minutes of aortic occlusion and during 40 minutes of reperfusion. Mean amplitudes of evoked potentials recovered from the caudal lumbar spinal cord decreased to 50% of original values at minute 12.2. Upon release of occlusion, the evoked potentials returned to baseline levels and remained there throughout the period of reperfusion. Sciatic nerve amplitudes decreased to 50% of original values at minute 4.5. In no subject could wave forms be recovered after minute 9.0. Upon release of occlusion, the evoked potentials returned to baseline levels and above, then deteriorated to 29 +/- 12% after 40 minutes of reperfusion. We concluded that transcranially induced evoked potentials were highly sensitive to spinal cord ischemia. Evoked potentials recovered from the sciatic nerve were consistent with functional grey matter immediately upon reperfusion, but deteriorated during reperfusion.