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Biomedical subjects

N H Dodman

Publications and source records attributed to N H Dodman.

At least 19 recordsLinked to original sources

Phenobarbital-responsive episodic dyscontrol (rage) in dogs.

Episodic dyscontrol (rage) was diagnosed from the clinical history, electroencephalographic findings, and response to oral treatment with phenobarbital in 3 dogs. Clinical features included a mood change heralding aggressive incidents, explosive aggression directed at people or objects, and a postaggressive phase characterized by lethargy and lack of responsiveness. Abnormal electroencephalographic findings included spike activity in the temporal recordings. All 3 dogs responded well to anticonvulsant medication with phenobarbital.

Aggression

The case against intraoperative ECG monitoring.

It can be seen that ECG monitoring has its limitations; however, if it is employed correctly, it can be an invaluable adjunct to physical monitoring. The ECG does not provide information about the cardiac contractile state or hemodynamic status and may not always permit the facile resolution of dysrhythmias; however, in conjunction with other forms of cardiovascular monitoring, the ECG permits the anesthetist to have greater confidence in cardiovascular events occurring during anesthesia and permits the early detection and treatment of cardiac rhythm disturbances.

Anesthesia, General

Pharmacokinetics and milk residues of butorphanol in dairy cows after single intravenous administration.

The pharmacokinetics of butorphanol tartrate were investigated following intravenous administration of 0.25 mg/kg of body weight to six healthy non-lactating Jersey cows. Three lactating Holstein cows also received 0.045 mg of butorphanol/kg of body weight intravenously to determine the extent and duration of drug transfer into milk. A radioimmunoassay technique was used to measure butorphanol concentrations in plasma and milk. The disposition of butorphanol following intravenous administration was characterized by rapid and extensive distribution followed by a slower elimination phase. Apparent volume of distribution was 4.178 +/- 1.145 (mean +/- SD) 1/kg, mean elimination half-life was 82 min, and clearance was 34.6 +/- 7.7 ml/min/kg. Trace quantities of butorphanol were detected in the cow's milk for up to 36 h following administration. These pharmacokinetic data were compared with pharmacokinetic and pharmacodynamic data for butorphanol in other species and for three other potent opioids in related ruminant species.

Animals

Postanesthetic compartmental syndrome in a horse.

After surgery, high intramuscular pressures were measured in a horse with clinical signs of postanesthetic myopathy that developed following a 2.25-hour surgical procedure. In the postoperative period, tests for muscular and neurologic integrity were made, including measurement of intracompartmental muscle pressure.

Anesthesia, General

Gas conductance during high-frequency oscillatory ventilation in large animals.

Three sheep, a foal, a pony, and a calf were anesthetized and ventilated for short periods, using a high-frequency oscillatory ventilator. The efficiency of CO2 elimination was characterized at various oscillatory frequencies (50 to 30 Hz) and various tidal volumes, although the tidal volume used was always less than the measured dead space of the animal. In general, increasing either the oscillatory frequency or tidal volume increased CO2 elimination, but increasing the tidal volume had more effect. The relationship between these 3 variables was best described by a power law equation. Ventilatory frequencies and tidal volumes required to maintain eucapnia in the species studied were extrapolated from the results and, when technically possible, the potential of the technique to maintain eucapnia was tested in extended runs. The animals were supported successfully over this period, with normal blood gas tensions and no detrimental effects to heart rate and rhythm or arterial blood pressure.

Anesthesia

Use of narcotic antagonists to modify stereotypic self-licking, self-chewing, and scratching behavior in dogs.

We evaluated 2 narcotic antagonists, naltrexone and nalmefene, for treatment of refractory self-licking, self-chewing, and scratching behavior in dogs. Eleven dogs with various irritative or pruritic disorders were medicated with naltrexone (1 mg/kg of body weight, sc) or nalmefene (1 to 4 mg/kg, sc), after a period of control observation during which the dogs had not been medicated. The time for which the dogs were involved in self-licking, self-chewing, or scratching was determined retrospectively by analysis of videotapes. The rates of involvement in either activity before and after treatment were calculated and compared statistically. Treatment with a narcotic antagonist significantly reduced the time spent self-licking, self-chewing, or scratching in 7 of 11 dogs, was partially effective in 3 dogs, and was ineffective in one dog. Dogs with acral lick dermatitis responded most to treatment.

Animals

Postanesthetic hind limb adductor myopathy in five horses.

Five horses that underwent prolonged anesthesia (greater than 3 hours) in dorsal recumbency for a surgical procedure were unable to stand after recovery and were euthanatized. A provisional diagnosis of postanesthetic myopathy was confirmed at necropsy in all 5 horses. However, distribution of affected muscles in these horses was atypical, because there was bilateral hind limb adductor muscle involvement.

Anesthesia, General

Use of a narcotic antagonist (nalmefene) to suppress self-mutilative behavior in a stallion.

Nalmefene, an opioid antagonist, caused a decrease in self-mutilative behavior in a 500-kg stallion. Self-mutilative attempts were counted during a control period and on 4 subsequent occasions after the IM administration of 100 mg, 200 mg, 400 mg, or 800 mg of nalmefene. The frequency of self-mutilation decreased with increasing doses of nalmefene and was virtually abolished with the 800-mg dose.

Animals

Pharmacokinetics of dantrolene sodium in horses.

The pharmacokinetics of dantrolene sodium were investigated in horses following both intravenous (2 mg/kg) and intragastric (4 mg/kg) administration. Two ponies also received dantrolene sodium intravenously (2 mg/kg) in a pilot study to obtain preliminary kinetic data and to determine urinary and biliary excretion of the intact drug. Distribution and elimination of dantrolene was rapid, resulting in an elimination half-life of 129 +/- 8 (SEM) min and a whole body clearance of 4.16 +/- 0.52 ml/min/kg. Following intragastric administration, dantrolene rapidly acheived peak concentrations within 1.5 h, but was incompletely absorbed, with a bioavailability of 39 +/- 10%. Small amounts of intact drug were recovered in urine and bile. Based upon disposition kinetics of dantrolene in these studies, intravenous and intragastric dosage regimens were determined which would maintain blood dantrolene concentrations within the predicted clinically effective range.

Animals

Investigation into the use of narcotic antagonists in the treatment of a stereotypic behavior pattern (crib-biting) in the horse.

Crib-biting in horses is a repetitive behavior pattern which may involve the activation of both narcotic receptors and dopamine receptors in the CNS. Crib-biting frequency, determined in 7 nontreated horses under controlled conditions, was usually linear for many hours and ranged from 0.3 to 14.9 bites/min. Intravenous or IM injections of narcotic antagonists decreased these rates to almost zero by about 20 minutes after the injection was given. The duration of the response to a single injection ranged from 20 minutes for naloxone to 4 hours or more for nalmefene and diprenorphine. Effective doses were 0.02 to 0.04 mg of naloxone/kg, 0.04 mg of naltrexone/kg, 0.08 mg of nalmefene/kg, and 0.02 to 0.03 mg of diprenorphine/kg. Crib-biting could be prevented completely for up to a week by continuous infusion of 5 to 10 mg of nalmefene/hr. Crib-biting resumed when the infusion was discontinued, and plasma nalmefene concentrations decreased to below 5 ng/ml. Doses of nalmefene as large as 0.4 mg/kg, IV, produced only minor side effects. These side effects included some passage of semifluid fecal material, intermittent penile relaxation, and mild sedation. Treated horses responded normally to external stimuli, retained their appetites, and performed appropriately when ridden. Sedation wore off during the course of prolonged infusions. Narcotic antagonists may provide a novel and effective treatment of stereotypic behavior disorders.

Animals

Inhalation therapy. Oxygen administration, humidification, and aerosol therapy.

In addition to receiving treatment for the primary disease, patients with advanced respiratory disorders may benefit from other forms of respiratory support. This article discusses three techniques of inhalation therapy that will aid in maintaining an optimal pulmonary environment and in normalizing arterial oxygenation. The role of aerosol therapy in direct intrapulmonary administration of pharmaceuticals is also discussed.

Adrenal Cortex Hormones

Xylazine-ketamine-oxymorphone: an injectable anesthetic combination in swine.

A xylazine, ketamine, and oxymorphone combination was investigated to determine its effectiveness as an injectable anesthetic regimen for use in swine. The combination was found to provide good narcosis, analgesia, and muscle relaxation, and was considered to be adequate for minor surgery. The intravenous dose rate was xylazine, 2mg/kg; ketamine, 2mg/kg; and oxymorphone, 0.075mg/kg. The dose of each component was doubled when the intramuscular route was used.

Anesthesia, Intravenous

Complications of saffan anaesthesia in cats.

Complications associated with Saffan anaesthesia were recorded following 100 administrations of the anaesthetic to cats. Hyperaemia or oedema of the pinnae or forepaws was recorded in 69 per cent of administrations. Other common complications included coughing and partial laryngean spasm at intubation, cyanosis, postoperative vomiting and opisthotonus. Suggestions are made for minimising the incidence of such complications.

Alfaxalone Alfadolone Mixture

Paradoxical excitement following the intravenous administration of azaperone in the horse.

The rapid intravenous administration of the butyrophenone tranquilliser, azaperone, at a dose rate of 0.29-0.57 mg/kg body weight resulted in the immediate onset of excitement and ataxia of varying degree in over half the animals. The severity of the reaction appeared to be related to the size of the animal. Other side effects such as salivation, sweating, muscle tremor and vocalisation were also observed. The possible causes of this paradoxical reaction to the tranquilliser are discussed.

Animals

Clinical observations on the antagonism of immobilon by naloxone in dogs.

The effectiveness of naloxone hydrochloride in reversing Immobilon anaesthesia was evaluated in 14 dogs. Although a dose rate of 0.02 mg per kg body-weight briefly reversed the respiratory and cardiovascular depression, a dose of at least 0.6 mg per kg body-weight was required before full recovery of consciousness occurred. The action of naloxone was found to be relatively short lived and relapse tended to occur after 10 to 15 minutes. The implications of these findings are discussed in relation to the use of naloxone in the event of accidental self-administration of Immobilon in man.

Anesthesia