Characterization of a reversible lameness model in the horse.

OBJECTIVE: Characterization of a model of reversible foot lameness in the horse. METHODS: Both forelimb hooves were fitted with a circumferential clamp. After three baseline measurements utilizing a force platform, one clamp was tightened to induce a grade 2.5/5 lameness and left in place for 120 hours. Serial heart rate and force platform measurements were obtained and the asymmetry index was calculated. After 120 hours, the clamp was released and force platform data recorded until the horse returned to soundness. The procedure was repeated for the opposite forelimb. The responses of treatment compared with the control for each outcome were analysed using linear mixed models. Time, limb (left or right), order of treatment, and interaction between time and order were used as fixed effects, whereas horse and limb were used as random effects. RESULTS: There was a significant increase in lameness associated with time and treatment order, where the second limb treated was more lame, based on the force platform data. The heart rate increased significantly with time and was significantly greater while the first limb was being treated. There was a significant effect of time on the increased subjective lameness score. CLINICAL SIGNIFICANCE: The lameness was present throughout the measurement period, though the level of lameness lessened with time. The model may be applicable for evaluation of mechanisms to treat pain in the horse. The reason for the difference in treatment order needs to be identified.

Ultrasonographic pregnancy detection and inhalation anesthesia in the gray short-tailed opossum (Monodelphis domestica).

Female gray short-tailed opossums (Monodelphis domestica) with known breeding dates were anesthetized with isoflurane for ultrasonographic pregnancy detection. Beginning on gestational day 9, gravid females could be identified using a 9-MHz mechanical sector-scanning transducer equipped with a standoff pad. Fluid-filled vesicles 3 to 4 mm in diameter were seen within the thick-walled uteri on gestational days 9 and 10. Visualization revealed loss of individual vesicles, with replacement by thick, irregular uterine walls and some free luminal fluid by gestational days 12 and 13. On the basis of subsequent birth of pups, sonographic diagnosis of pregnancy was accurate in 27 of 28 oppossums examined.

Bacterial isolates from plaque and from blood during and after routine dental procedures in dogs.

OBJECTIVE: This study evaluates the association between dental procedures and bacteremia in dogs, including a comparison of bacteria isolated from plaque and blood, severity of the bacteremia versus the severity of dental disease, and the longevity of bacteremia. STUDY DESIGN: Bacteria cultured from the blood over time were compared with those isolated from the plaque and crevicular fluid and in relation to severity of dental disease. ANIMALS OR SAMPLE POPULATION: Twenty adult greyhounds. METHODS: Blood samples were collected for culture before induction of general anesthesia, immediately after intubation, 20 minutes after initiation of the dental procedure, and at 10-minute intervals until 10 minutes after the dental procedure was completed. Samples of plaque were taken for microbiological culture. RESULTS: Sixty to ninety percent of the bacterial genera isolated from the plaque were present in the blood. Dogs classified according to severity of dental disease showed no difference in the total number of different species or number of different Gram-negative, Gram-positive, or anaerobic bacteria isolated from plaque or blood (P < .05). Bacteremia was present in all of the dogs studied, within 40 minutes from the initiation of the dental procedure, regardless of the severity of oral disease. CONCLUSIONS: Gram-negative, Gram-positive, and anaerobic bacteria are present in blood during dental procedures; the bacteremia can persist beyond the dental procedure, and is not associated with the severity of dental disease. CLINICAL RELEVANCE: The nature and extent of bacteremia occurring during routine dental procedures is important in understanding a potential risk to dogs.

Cardiopulmonary responses in healthy dogs during endoscopic examination of the gastrointestinal tract.

Cardiopulmonary responses were evaluated in 12 dogs undergoing endoscopy (gastroscopy and enteroscopy). Constant endoscopic insufflation was used to distend the stomach and small intestine for 30 minutes in groups of small (< 10 kg; n = 4), medium (10 to 20 kg; n = 4), and large (> 20 kg; n = 4) dogs. Cardiopulmonary measurements within groups prior to gastric distention (preendoscopy) were compared with postendoscopy measurements and with those made during endoscopy. After distending the stomach and small intestine, increased luminal pressure within the body of the stomach and in the descending duodenum (P < 0.05) and increased abdominal girth (P < 0.05) were observed, with the greatest changes in small dogs. Caudal vena cava pressures and mean arterial and pulmonary artery pressures increased (P < 0.05) during endoscopy. Cardiac index varied, with small dogs having greater cardiac index (P < 0.05) during endoscopy, compared with that in medium and large dogs. Minute volume remained unchanged during insufflation, despite a decrease in tidal volume (P < 0.05), because of an increase in respiratory rate (P < 0.05). Arterial blood gas analysis revealed a mild, mixed metabolic/respiratory acidosis in all groups. Although cardiopulmonary changes associated with gastrointestinal tract endoscopy were common, the changes were often small and of little clinical significance.

Pharmacokinetics of propofol in mixed-breed dogs and greyhounds.

Pharmacokinetics and recovery characteristics of propofol in Greyhounds and mixed-breed dogs were compared. In all dogs, disposition of propofol was adequately described by a 2-compartment open model, with a rapid distribution phase followed by a slower elimination phase. When findings in Greyhounds were compared with those in mixed-breed dogs, significant differences were observed in mean concentrations of propofol in blood, recovery characteristics, and estimates for apparent volume of distribution, volume of distribution at steady state, and total body clearance. In addition, Greyhounds recovered from anesthesia at higher concentrations of propofol than did mixed-breed dogs. A secondary peak in blood propofol concentration was observed in 8 of 10 Greyhounds and in 5 of 8 mixed-breed dogs. This peak corresponded to the time of return of the righting reflex.

Evaluation of hemostatic analytes after use of hypertonic saline solution combined with colloids for resuscitation of dogs with hypovolemia.

The effects of hypertonic saline solution (HTSS) combined with colloids on hemostatic analytes were studied in 15 dogs. The analytes evaluated included platelet counts, one-stage prothrombin time, activated partial thromboplastin time, von Willebrand's factor antigen (vWf:Ag), and buccal mucosa bleeding times. The dogs were anesthetized, and jugular phlebotomy was used to induced hypovolemia (mean arterial blood pressure = 50 mm of Hg). Treatment dogs (n = 12) were resuscitated by infusion (6 ml/kg of body weight) of 1 of 3 solutions: HTSS combined with 6% dextran 70, 6% hetastarch, or 10% pentastarch. The control dogs (n = 3) were autotransfused. Hemostatic analytes were evaluated prior to induction of hypovolemia (baseline) and then after resuscitation (after 30 minutes of sustained hypovolemia) at 0.25, 0.5, 1, 6 and 24 hours. All treatment dogs responded rapidly and dramatically to resuscitation with hypertonic solutions. Clinically apparent hemostatic defects (epistaxis, petechiae, hematoma) were not observed in any dog. All coagulation variables evaluated, with the exception of vWf:Ag, remained within reference ranges over the 24-hour period. The vWf:Ag values were not statistically different than values from control dogs, and actual values were only slightly lower than reference ranges. Significant (P < or = 0.04) differences were detected for one-stage prothrombin time, but did not exceed reference ranges. The results of this study suggested that small volume HTSS/colloid solutions do not cause significant alterations in hemostatic analytes and should be considered for initial treatment of hypovolemic or hemorrhagic shock.

Right-to-left patent ductus arteriosus with dysplastic left ventricle in a dog.

A 6-week-old Siberian Husky pup had an unusual group of congenital heart anomalies that included a right-to-left patent ductus arteriosus, a small left ventricular chamber and ascending aorta, and a dysplastic mitral valve that may have been stenotic. Anomalies were diagnosed, using cardiac catheterization, angiocardiography, and blood gas determinations. Findings were confirmed by postmortem examination.

Oral pentobarbital intoxication in a bitch.

Pentobarbital intoxication in a 5-year-old female Samoyed was confirmed by the finding of a high concentration of the drug in serum. The dog apparently had consumed one of her pups, which had been euthanatized the day before with a 26% sodium pentobarbital solution. She was admitted in a condition consistent with light general anesthesia. The dog recovered after gastric lavage supportive therapy, and the administration of an alkalinizing solution to hasten drug excretion. This case demonstrates the hazards associated with indiscriminate disposal of carcasses containing large amounts of euthanasia solution.

Unusual response following use of succinylcholine in a horse anesthetized with halothane.

A syndrome similar to malignant hyperthermia developed in a 545-kg Quarter Horse while anesthetized with halothane for cataract removal. Succinylcholine administration caused prolonged, severe muscle fasciculations followed by tachycardia, and an elevated blood pressure. Later, while the horse was still under anesthesia, its body temperature rose 2 degrees C, and respiratory acidosis developed. Myositis developed after surgery, but the horse recovered.