Perioperative mortality in small animal anaesthesia

Anaesthetic complications have been studied intermittently in small animal practice. Current estimates suggest that approximately 0.1–0.2% of healthy and 0.5–2% of sick dogs and cats die of an anaesthetic-related death. This is substantially greater than the risk of mortality reported in human anaesthesia. Recent work has identified the post-operative period as the highest risk period and has documented a number of risk factors for mortality. Knowledge of factors associated with anaesthetic-related death and high risk peri-operative periods could aid patient management and reduce complications.     

Renal biopsy: a retrospective study of methods and complications in 283 dogs and 65 cats

Renal biopsy often is required to establish a definitive diagnosis in dogs and cats with renal disease. In this retrospective study, we determined the complications of renal biopsy as well as factors that may be associated with development of complications and procurement of adequate renal biopsy specimens in 283 dogs and 65 cats. Data extracted from medical records at 4 institutions were evaluated using logistic regression. Proteinuria was the most common indication for renal biopsy in dogs. Complications were reported in 13.4 and 18.5% of dogs and cats, respectively. The most common complication was severe hemorrhage; hydronephrosis and death were uncommon. Dogs that developed complications after renal biopsy were more likely to have been 4 to < 7 years of age and > 9 years, to weigh < or = 5 kg, and to have serum creatinine concentrations > 5 mg/dL. The majority of biopsies from both dogs (87.6%) and cats (86.2%) were considered to be of satisfactory quality. Biopsies from dogs were more likely to be of high quality if they were obtained when the patient was under general anesthesia and more likely to contain only renal cortex if they were obtained by surgery. We concluded that renal biopsy is a relatively safe procedure, with a low frequency of severe complications. Hospital practices and patient variables have the potential to impact both the quality of the specimen obtained and the rate of complications.     

The prevalence of albuminuria in dogs and cats in an ICU or recovering from anesthesia

Objective – To evaluate the prevalence of albuminuria in dogs and cats admitted to the ICU or recovering from an anesthetic event. Design – Prospective clinical study over a 10‐week period in 2003. Setting – Veterinary teaching hospital. Animals – One hundred and five dogs and 22 cats. Interventions – Urine was collected from dogs and cats admitted to the ICU or recovering from an anesthetic event. When possible, a second urine sample was collected approximately 48 hours later from those animals that had albuminuria during the initial screening. Measurements and Main Results – All dog samples and most cat samples were screened for albumin using a commercial point‐of‐care immunoassay. Aliquots of samples that tested positive were stored at –20°C until subsequent albumin quantification via antigen capture ELISA. Albuminuria was detected in 63 of 105 (60.0%) dogs and in 14 of 22 (63.6%) cats; the prevalence was higher in animals admitted to ICU than in those recovering from anesthesia. In subsequent samples from 26 dogs, urine albumin decreased in 20 (76.9%) when compared with the first sample; urine albumin was undetectable in 5 (19.2%). In subsequent samples from 6 cats, 4 (66.7%) had decreases in urine albumin when compared with the first sample; 1 (16.7%) was negative for urine albumin. Eleven of 12 dogs (91.7%) and 3 of 4 cats (75%) that died within 3 days of admission to the ICU had abnormal urine albumin; whereas 52 of 93 (55.9%) and 11 of 18 (61.1%) dogs and cats, respectively, who survived more than 3 days had abnormal urine albumin. Dogs with albuminuria were at increased risk of death. Conclusions – The prevalence of albuminuria in animals admitted to the ICU or recovering from anesthesia is higher than reported previously and transient in some patients. The presence of albuminuria may be a negative prognostic indicator in this population.     

Peri-operative morbidity associated with ovariohysterectomy performed as part of a third-year veterinary surgical-training program

The present study describes the morbidity associated with ovariohysterectomy (OVH) when performed by third-year veterinary students as part of a surgical-training program. Data recorded from medical records included signalment, concurrent illness(es), surgical procedure(s), anesthesia and surgery time, anesthetic and surgical complications, and semester performed. The students' surgical training before the OVH included 39 lecture and 26 laboratory hours. In the present study, 513 animals (206 dogs and 307 cats) were included, of which 120 (23.4%) animals had concurrent illnesses. Median anesthesia time was 145 minutes (ranging from 65 to 240) for cats and 180 minutes (ranging from 90 to 360) for dogs. Median surgery time was 105 minutes (ranging from 50 to 210) for cats and 140 minutes (ranging from 65 to 265) for dogs. There were two (0.4%) major anesthetic complications, one resulting in death. There were 206 (41.7%) minor anesthetic complications, the most common being hypothermia. There were 17 (3.3%) major surgical complications, the most common being body wall dehiscence (n=15), and 49 (9.5%) minor surgical complications, the most common being seroma formation (n=35). Complications were comparable to previous reports. Specific aspects of the program identified for improvement included placing greater emphasis on securely tying the terminal knot of a simple continuous suture pattern to prevent body wall dehiscence, improved measures to reduce post-operative hypothermia, and implementing stricter health screening of animals before enrollment into the program. Faculty program coordinators are encouraged to conduct similar studies so that best practices can be shared and outcomes can be compared as we work toward determining the ideal methods of training students to instill core surgical competencies.     

Evaluation of age and American Society of Anesthesiologists (ASA) physical status as risk factors for perianesthetic morbidity and mortality in the cat

Objective: To evaluate age and American Society of Anesthesiologists (ASA) physical status as risk factors for perianesthetic morbidity/mortality in cats. Design: Prospective cohort study. Setting: Institution teaching hospital. Animals: 138 cats ≥ 6 months of age that received inhalation anesthesia for ≥ 30 min Interventions: Observations were made during the 24 h post‐anesthetic period. Measurements and main results: Sixty‐one females and 77 males were included. Serious perianesthetic complications occurred in 15 cats (15/138; 11%), including cardiopulmonary arrest in 3 cats (3/138; 2%), and death or euthanasia in 7 cats (7/138; 5%). Age was not a factor in establishing risk for developing serious or minor perianesthetic complications in the cats in this study. However, ASA status was a risk factor. Cats having an ASA status of 3 or more were nearly 4 times as likely to develop serious perianesthetic complications, even when accounting for the significant confounding effects of anesthesia duration. Conclusions: ASA status, but not age, was a risk factor for the development of serious or minor perianesthetic complications in the 138 cats included in this study.     

Results of the confidential enquiry into perioperative small animal fatalities regarding risk factors for anesthetic-related death in dogs

OBJECTIVE: To identify major risk factors associated with anesthetic-related death in dogs. DESIGN: Case-control study. ANIMALS: 148 dogs that died or were euthanized within 48 hours after undergoing anesthesia or sedation and for which anesthesia could not be reasonably excluded as a contributory factor (cases) and 487 control dogs that did not die within 48 hours after undergoing anesthesia or sedation (controls). PROCEDURES: Details of patient characteristics, preoperative evaluation and preparation, procedure, anesthetic and sedative agents used, monitoring, postoperative management, and personnel involved were recorded. Mixed-effects logistic regression modeling was used to identify factors associated with anesthetic-related death. RESULTS: An increase in physical status grade, urgency of the procedure, age, or intended duration of the procedure; a decrease in body weight; anesthesia for a major versus a minor procedure; and use of injectable agents for anesthetic induction and halothane for maintenance or use of inhalant anesthetics alone (compared with use of injectable agents for induction and isoflurane for maintenance) were associated with increased odds of anesthetic-related death. CONCLUSIONS AND CLINICAL RELEVANCE: The results suggested that specific factors could be associated with increased odds of anesthetic-related death in dogs. Knowledge of these factors should aid the preoperative assessment and perioperative management of dogs undergoing anesthesia and sedation.     

Epidemiologic factors, clinical findings, and vaccination status of rabies in cats and dogs in the United States in 1988. National Study Group on Rabies

Despite the availability of rabies vaccination through private veterinarians and government-sponsored rabies control programs, rabies was reported in an average of 338 cats and dogs per year from 1980 through 1987 in the United States. Information was collected on 90% of the 183 cats and 97% of the 119 dogs that were reported to have rabies in the continental United States in 1988. The median age of rabid cats and dogs was 1 year, and 81% were from rural areas. Compared with rabid cats, rabid dogs were more likely to have been male (66 vs 42%, odds ratio = 2.6), to have been kept as pets (84 vs 43%, odds ratio = 6.8), and to have had reported contact with wildlife before onset of illness (38 vs 14%, odds ratio = 3.8). Rabid cats accounted for a greater proportion of human rabies postexposure prophylaxis, bites to people, and exposures to other animals than did rabid dogs. Although the clinical signs of rabies varied, rabid cats were more likely than dogs to have had aggressive behavior (55 vs 31%, odds ratio = 2.8). In contrast, rabid dogs were more likely than cats to have had an illness consistent with a paralytic process. The median period between onset of illness and death was 3 days (range, less than 1 to 10) in rabid cats and dogs that were allowed to die of rabies. Vaccine failures were documented in 3 (1%) rabid animals (2 cats and 1 dog). All animals had received only a single dose of vaccine in their lifetime and were vaccinated when they were between 3 and 6 months old.     

Post‐anesthesia deafness in dogs and cats following dental and ear cleaning procedures

Objective The present study was performed to document hearing loss in dogs and cats following procedures performed under anesthesia. Most cases of reported hearing loss were subsequent to dental and ear cleaning procedures. Study design Prospective and retrospective case survey. Animals Subjects were dogs and cats with deafness, personally communicated to one author, cases discussed on a veterinary information web site, and cases communicated through a survey of general practice and dental specialist veterinarians. Methods Reported deafness cases were characterized by species (dog, cat), breed, gender, age, and dog breed size. Results Sixty‐two cases of hearing loss following anesthesia were reported between the years 2002 and 2009. Five additional cases were reported by survey respondents. Forty‐three cases occurred following dental procedures. Sixteen cases occurred following ear cleaning. No relationship was observed between deafness and dog or cat breed, gender, anesthetic drug used, or dog size. Geriatric animals appeared more susceptible to post‐anesthetic, post‐procedural hearing loss. Conclusions Deafness may occur in dogs and cats following anesthesia for dental and ear cleaning procedures, but the prevalence is low. The hearing loss appears to be permanent. Clinical relevance Deafness can be a consequence following anesthesia for dental or ear cleaning procedures. Older animals may have greater susceptibility.     

Factors associated with adverse outcomes during parenteral nutrition administration in dogs and cats

Background: Parenteral nutrition (PN) is increasingly used to support hospitalized dogs and cats. Published assessments of outcome are limited. Objective: Evaluate type and prevalence of complications and risk factors for death and complications in dogs and cats receiving PN. Animals: Three hundred and nineteen dogs and 112 cats that received PN at a teaching hospital between 2000 and 2008. Methods: Retrospective case review. Diagnosis, duration of PN administration, concurrent enteral feeding, death, and mechanical, septic, and metabolic complications were abstracted from medical records. Association of each parameter with complications and death was analyzed by binary logistic regression. Results: Pancreatitis was the most common diagnosis (109/319 dogs, 34/112 cats), and 137/319 dogs and 51/112 cats died. Dogs and cats received 113 ± 40% and 103 ± 32% of resting energy requirement, respectively. Mechanical (81/319 dogs, 16/112 cats) and septic (20/319 dogs, 6/112 cats) complications were not associated with death (P > .05). Hyperglycemia was the most common metabolic complication (96/158 dogs, 31/37 cats). Hypercreatininemia in dogs (8/79) was the only complication associated with death (P < .01). Chronic kidney disease in dogs, hepatic lipidosis in cats, and longer duration of inadequate caloric intake before PN in both species were negatively associated with survival (P < .05). Factors positively associated with survival included longer duration of PN administration in both species, enteral feeding in cats with any disease, and enteral feeding in dogs with respiratory disease (P < .05). Conclusions and Clinical Importance: PN can be effectively used to provide the energy requirements of most critically ill dogs and cats. Most complications accompanying PN administration do not affect survival.     

Postoperative pulmonary complications in dogs undergoing laparotomy: anesthetic and perioperative factors

Objective: To define the peri‐anesthetic risk factors that are associated with the development of postoperative pulmonary complications (PPCs) in dogs following laparotomy. Study design: Retrospective study. Animals: One hundred and sixty‐two dogs that underwent laparotomy at a veterinary teaching hospital. Methods: Cases were evaluated for factors including signalment, American Society of Anesthesiologists (ASA) physical status (PS) score, duration of fast, duration of anesthesia, anesthetic and analgesic protocols, fluid and blood product therapy, animal positioning, and postoperative temperature. Results: Statistically significant differences between dogs that developed PPCs and those that did not (nPPCs) were identified in the following categories: ASA PS score≥III (P=0.041), emergent surgery (P=0.038), longer duration of anesthesia (P=0.0462), and use of butorphanol or oxymorphone instead of hydromorphone for postoperative medication (P=0.04 and 0.015, respectively). Dogs that received transfusions of stored blood products (fresh frozen plasma or packed red blood cells) during their hospital stay were also more likely to develop PPCs (P=0.035 and 0.005, respectively). Dogs that developed PPCs were also more likely to have received antagonists for potent opiates or benzodiazepines postoperatively and to have recovered in the intensive care unit (ICU) (P=0.03 and 0.009, respectively). Conclusions: Dogs with ASA PS scores≥III, or those requiring longer or emergency anesthesia are at a higher risk of developing PPCs. Additionally, dogs receiving stored blood products in the perioperative period may be at risk for pulmonary complications. Dogs fitting criteria for the above risk factors should be monitored closely postoperatively for development of pulmonary complications.     

Absence of sensitization to epinephrine-induced cardiac arrhythmia and fibrillation in dogs and cats anesthetized with CI 744.

Ci 744 (20 mg/kg, given intramuscularly (IM) produced a reliable level of surgical anesthesia in both dogs and cats. Animals anesthetized in this way did not have an increased sensitivity to cardiac fibrillation after they were given epinephrine. Epinephrine-induced ventricular arrhythmia observed in C1 744-anesthetized animals was eliminated in cats and was markedly reduced in dogs by bilateral vagotomy. Myocardial fibrillation was not produced by epinephrine (0.1 to 100 mug/kg, intravenously (IV) in dogs and cats anesthetized with C1 744 alone. Pentobarbital anesthesia, like C1 744 anesthesia, did not sensitize the heart, whereas a significant number of thiamylal-halothane-anesthetized animals died from cardiac fibrillation after they had been given epinephrine. Additional dogs were anesthetized with C1 744 or pentobarbital and given a series of pressor and depressor agents (isoproterenol, epinephrine, tyramine, 1, 1-dimethyl-4-phenylpiperazium iodide (DMPP) plus bilateral carotid occlusion) before and after vagotomy. The responses with either anesthetic were similar with the exception that the reflex bradycardia to pressor agents was more evident in C1 744- than in pentobarbital-anesthetized dogs.     

Effect of pre-anesthetic meperidine on gastro-esophageal reflux in anesthetized dogs

Meperidine has been shown to decrease lower esophageal sphincter tone in monkeys and people, to have little effect in cats, and to physically increase it in dogs. We hypothesized that administration of meperidine to dogs before anesthesia would decrease the probability of GER during the subsequent anesthetic. In this randomized, prospective clinical trial we aimed to determine the incidence of GER in dogs undergoing elective orthopedic surgery and receiving either meperidine or morphine prior to anesthesia. Dogs were admitted to the study, if they were healthy, with no history of vomiting or dysphagia. Dogs were fasted overnight. Dogs were received either morphine (0.66 mg kg^–1 IM) or meperidine (8.8 mg kg^–1 IM) with acepromazine. Anesthesia in all dogs included thiopental and isoflurane in oxygen. To measure esophageal pH a sensor-tipped catheter was placed with the tip 5–7 cm cranial to the lower esophageal sphincter, and connected to a computer for continual data collection. Dogs were observed for vomiting after pre-medication, and the pH of any fluid running from the mouth or nose during anesthesia was measured. Gastro-esophageal reflux was defined as a decrease in esophageal pH below 4 or an increase above 7.5 for greater than 15 seconds. One-way anova was used to test significance of differences between groups in parametric variables. Fisher's Exact test was used to test significance of differences in incidence between groups. In dogs receiving meperidine the incidence of vomiting was 0, and of GER was 31% (4/13), compared to 60% (6/10) and 60% (6/10), respectively in dogs receiving morphine. In this preliminary study, the administration of pre-anesthetic meperidine was associated with a 29% reduction in the absolute risk of GER compared to morphine.     

Development and implementation of veterinary anesthesia medical quality standards for primary care

ObjectiveThe provision of general anesthesia is common in veterinary hospitals and procedures include some level of risk, up to and including mortality. A quality initiative was introduced with a focus on reducing canine and feline anesthesia mortality. This paper describes the development and implementation of risk-based medical quality standards (MQS) and resultant impacts on anesthesia mortality.Study designThis was a qualitative observational study. MQS focused on the provision of anesthesia were researched, developed and implemented. Anesthesia mortality rates, captured via an automated process based on the electronic medical record, were recorded before and after implementation. Compliance to standards was determined via hospital auditing.AnimalsClient-owned dogs and cats presenting to Banfield Pet Hospital (a national network of primary care hospitals) for elective and nonelective general anesthesia procedures. Over the course of the study, 2,038,318 dogs and 350,410 cats had a general anesthesia event.MethodsLiterature reviews and analysis of veterinary patient medical records identified risk factors associated with anesthesia mortality. Risk factors informed the development of MQS. Evidence-based standards focused on the provision of general anesthesia were written, reviewed, evaluated and edited. Implementation occurred over 6 months via a robust communication plan. Anesthesia mortality rates were continuously monitored before, during and after the introduction of standards. Compliance with all quality standards was assessed via hospital-based auditing performed on an annual basis.ResultsPrior to quality standards implementation, anesthesia mortality rates for dogs and cats combined was 7.4 deaths/10,000 procedures. At 6 months after implementation, the mortality rate was 6.24 deaths/10,000 procedures, representing a 16% decrease. Compliance with standards improved over time with continued focus and education.Conclusions and clinical relevanceDevelopment, implementation and continued focus on MQS can improve anesthetic safety and reduce anesthesia mortality in primary care veterinary hospitals.     

Duration of corneal anesthesia following topical administration of 0.5% proparacaine hydrochloride solution in clinically normal cats

OBJECTIVE: To determine duration of corneal anesthesia following topical administration of 0.5% proparacaine hydrochloride solution in domestic shorthair (DSH) cats. ANIMALS: 20 clinically normal DSH cats. PROCEDURES: Baseline corneal touch threshold (CCT) was established by use of a Cochet-Bonnet aesthesiometer. Treatment consisted of a single 50-microL topical application of an ophthalmic preparation of 0.5% proparacaine solution to a randomly selected eye of each cat. The corneal touch threshold was assessed 1 and 5 minutes after application to the cornea and at 5- minute intervals thereafter for 60 minutes. RESULTS: Corneal sensitivity, as determined by Cochet-Bonnet aesthesiometry, was significantly reduced from baseline for 25 minutes following topical administration of ophthalmic proparacaine. Maximal anesthetic effect lasted 5 minutes. CONCLUSIONS AND CLINICAL RELEVANCE: As determined by Cochet-Bonnet aesthesiometry, duration of anesthetic effects on the cornea induced by a single topical application of an ophthalmic preparation of 0.5% proparacaine solution in DSH cats is considerably shorter than the reported duration of corneal anesthesia in dogs.     

Early spay-neuter: clinical considerations

Early spay-neuter is ovariohysterectomy or castration of puppies or kittens 6 to 14 weeks of age. Pediatric animals may have an enhanced response to relatively low doses of anesthetic agents. Animals should be fasted no more than 3 to 4 hours before surgery to prevent hypoglycemia, and hypothermia should be avoided. Heart and respiratory rates must be monitored carefully throughout anesthesia. Pediatric gonadectomy surgeries are quick with minimal bleeding. Anesthetic recovery is rapid. No significant short-term or long-term effects have been reported. Prepuberal gonadectomy is most useful for humane organizations and conscientious breeders wishing to preclude reproduction of pet dogs and cats while placing animals at a young enough age to optimize socialization and training.     

Retrospective analysis of complications associated with retrobulbar bupivacaine in dogs undergoing enucleation surgery

ObjectiveTo investigate complications associated with, and without, bupivacaine retrobulbar local anesthesia in dogs undergoing unilateral enucleation surgery.Study designRetrospective, observational study.AnimalsA total of 167 dogs underwent unilateral enucleation surgery via a transpalpebral approach.MethodsRecords from 167 dogs that underwent unilateral enucleation surgery that did (RB) or did not (NB) include retrobulbar bupivacaine anesthesia were reviewed, including anesthetic record, daily physical examination records, surgery report, patient discharge report and patient notes within 14 days of the surgery. Specific complications and severity were compared between RB and NB using the Wilcoxon rank-sum test. A ‘complication burden’ (0–5) comprising five prespecified complications was assigned and tested using rank-sum procedures. Statistical significance was set to 0.05.ResultsGroup RB included 97 dogs and group NB 70 dogs. Dogs in NB had a 17.0 percentage points (points) greater risk for a postoperative recovery complication (38.6% versus 21.6%; 95% confidence interval: 3.0–30.6 points; p = 0.017). There was inconclusive evidence that dogs in group RB had a lower risk of requiring perioperative anticholinergic administration (12.4% versus 22.9%; 10.5 points; p = 0.073). Other complications were similar between groups RB and NB with risks that differed by <10 points. The risk of hemorrhage was similar between groups RB (22.7%) and NB (20.0%) with no significant difference in the level of severity (p = 0.664).Conclusions and clinical relevanceIn this retrospective study, the use of retrobulbar bupivacaine for enucleation surgery in dogs was not associated with an increased risk of major or minor complications.     

Anesthesia and Analgesia in Rabbits and Rodents

Rabbits and rodents are popular pets and are often presented to veterinarians for evaluation and medical treatment. Anesthesia in exotic pets is required for many diagnostic and surgical procedures and is associated with a higher perioperative risk in rabbits and rodents when compared with dogs and cats. Inhalation anesthetic agents are commonly used as the sole source of anesthesia in small rodents, whereas injectable agents in combination with inhalation anesthesia are often used for rabbits and larger rodents. Analgesia is an important component of exotic pet medicine. Although it may be difficult to recognize signs of pain in companion exotic mammals, adequate pain management should always be provided. Opioid and nonsteroidal antiinflammatory drugs are the analgesic medications of choice, but others should be considered (e.g., local anesthetic agents). This article provides an update of the current literature regarding anesthesia and analgesia in rabbits and rodents.     

Coccygeal epidural with local anesthetic for catheterization and pain management in the treatment of feline urethral obstruction

Objective – To describe the technique for performing a coccygeal epidural injection of local anesthetic to facilitate catheterization in male cats with urethral obstructions using low‐dose sedation. Significance – Prompt diagnosis and relief of urethral obstructions is important as many cats may have developed marked metabolic abnormalities at the time of presentation. General anesthesia in these patients may be associated with significant risk for complications. Pain management is also an essential treatment goal, and this technique relieves urethral and penile pain during the unblocking process. Conclusion – Coccygeal epidurals can be used safely to provide analgesia to the penis and urethra and to the authors' knowledge, is a novel treatment modality to aid in the relief of urethral obstructions in male cats.     

Effects of a standardized anesthetic protocol on hematologic variables in healthy cats

This study evaluated the effects of an anesthetic protocol using intravenous ketamine and midazolam, and intramuscular buprenorphine on hematologic variables in cats. Twelve healthy adult cats had blood collected for a complete blood count before and after the induction of anesthesia. There were significant decreases in red blood cell counts, hemoglobin concentrations and hematocrits after the induction of anesthesia. On average, red blood cell counts and hematocrits decreased by 25%, and hemoglobin concentrations decreased by 24%. Based on hematocrit, 3/12 samples (25%) taken while the cats were anesthetized would have been interpreted as belonging to anemic patients while none of the cats would have been considered anemic before anesthesia. This study suggests that a complete blood count performed on blood taken under anesthesia with this anesthetic protocol should be interpreted cautiously in order to not make a false diagnosis of anemia.     

Propofol anesthesia.

Although questions may still remain regarding the use of this unique sedative-hypnotic drug with anesthetic properties in high-risk patients, our studies have provided cardiopulmonary and neurological evidence of the efficacy and safety of propofol when used as an anesthetic under normal and selected impaired conditions in the dog. 1. Propofol can be safely and effectively used for the induction and maintenance of anesthesia in normal healthy dogs. Propofol is also a reliable and safe anesthetic agent when used during induced cardiovascular and pulmonary-impaired conditions without surgery. The propofol requirements to induce the safe and prompt induction of anesthesia prior to inhalant anesthesia with and without surgery have been determined. 2. The favorable recovery profile associated with propofol offers advantages over traditional anesthetics in clinical situations in which rapid recovery is important. Also, propofol compatibility with a large variety of preanesthetics may increase its use as a safe and reliable i.v. anesthetic for the induction and maintenance of general anesthesia and sedation in small animal veterinary practice. Although propofol has proven to be a valuable adjuvant during short ambulatory procedures, its use for the maintenance of general anesthesia has been questioned for surgery lasting more than 1 hour because of increased cost and marginal differences in recovery times compared with those of standard inhalant or balanced anesthetic techniques. When propofol is used for the maintenance of anesthesia in combination with a sedative/analgesic, the quality of anesthesia is improved as well as the ease with which the practitioner can titrate propofol; therefore, practitioners are able to use i.v. anesthetic techniques more effectively in their clinical practices. 3. Propofol can induce significant depression of respiratory function, characterized by a reduction in the rate of respiration. Potent alpha 2 sedative/analgesics (e.g., xylazine, medetomidine) or opioids (e.g., oxymorphone, butorphanol) increase the probability of respiratory depression during anesthesia. Appropriate consideration of dose reduction and speed of administration of propofol reduces the degree of depression. Cardiovascular changes induced by propofol administration consist of a slight decrease in arterial blood pressures (systolic, mean, diastolic) without a compensatory increase in heart rate. Selective premedicants markedly modify this characteristic response. 4. When coupled with subjective responses to painful stimuli, EEG responses during propofol anesthesia provide clear evidence that satisfactory anesthesia has been achieved in experimental dogs. When propofol is used as the only anesthetic agent, a higher dose is required to induce an equipotent level of CNS depression compared with the situation when dogs are premedicated. 5. The propofol induction dose requirement should be appropriately decreased by 20% to 80% when propofol is administered in combination with sedative or analgesic agents as part of a balanced technique as well as in elderly and debilitated patients. As a general recommendation, the dose of propofol should always be carefully titrated against the needs and responses of the individual patient, as there is considerable variability in anesthetic requirements among patients. Because propofol does not have marked analgesic effects and its metabolism is rapid, the use of local anesthetics, nonsteroidal anti-inflammatory agents, and opioids to provide postoperative analgesia improves the quality of recovery after propofol anesthesia. 6. The cardiovascular depressant effects of propofol are well tolerated in healthy animals, but these effects may be more problematic in high-risk patients with intrinsic cardiac disease as well as in those with systemic disease. In hypovolemic patients and those with limited cardiac reserve, even small induction doses of propofol (0.75-1.5 mg/kg i.v.) can produce profound hypotens