Coagulation in the equine intensive-care patient

Thrombotic disorders are common in the critically ill adult horse. Jugular vein phlebitis/thrombophlebitis, laminitis and organ, eg, colonic and/or pulmonary vessel thrombosis, are all important thrombotic disorders in the horse. Bleeding disorders are most commonly caused by thrombocytopenia or rupture of a large vessel. The measurement of clotting times, platelet number and function, fibrin degradation products and specific coagulation proteins, eg, Antithrombin III, can be routinely performed on the critically ill horse. Treatments for thrombotic disorders include fluids, plasma, anticoagulants and fibrinolytic enzymes. Treatments for bleeding disorders include fluids, blood products, aminocaproic acid, in addition to surgical repair or occlusion of an injured large vessel.     

Anesthesia for the acute abdomen patient

Patients with acute abdomen often have marked physiologic and pathologic changes, making anesthesia both challenging and potentially hazardous for the patient. A thorough understanding of the pathophysiologic mechanisms of cardiovascular function under anesthesia and selection of appropriate anesthetic protocols are critical to a successful anesthetic outcome. The goal is to produce anesthesia while minimizing depression of the cardiovascular system. Monitoring and management of acid-base and cardiovascular function serve to ensure appropriate oxygen delivery to the tissues during anesthesia. Postoperative management can significantly influence patient outcome following anesthesic recovery, and must therefore be considered in the anesthetic plan. Finally, pain management in all patients is an important aspect of case management, and should not be overlooked. This article serves to educate the clinician in the above-described areas in regard to the acute abdomen patient.     

Anesthesia of the critically ill equine patient.

There is a plethora of information regarding anesthetic management of horses; however, controlled studies of the critically ill equine patient are few.These patients should be managed like any equine anesthetic candidate but much more stringently:I. Preoperative evaluation and appropriate therapy may represent the difference between life and death during the intraoperative and recovery periods. 2. The anesthetic induction and maintenance protocol should be based on the individual situation of the veterinary facility and personnel("comfort zone"). 3. Appropriate monitoring and intraoperative supportive measures are essential. 4. The anesthetic period is a significant perturbation to homeostasis. Even if the horse seems to have done well (ie, as indicated by the cardiopulmonary values), a problem-free anesthetic period does not guarantee a successful recovery, and close monitoring should continue until the horse is ambulatory. 5. Critically ill patients are often in a negative energy balance. Supportive measures to ensure an adequate caloric intake, such as enteral or parenteral nutrition, facilitate healing and return of homeostasis.     

Anesthesia of the sighthound

The sighthounds are an ancient group of dog breeds that have been selectively bred for high-speed pursuit of prey by sight. Probably as a consequence of this selection process, these dogs have a number of idiosyncrasies that can potentially adversely affect their anesthetic management. These include (1) nervous demeanor which can lead to stress-induced clinical complications, such as hyperthermia; (2) lean body conformation with high surface-area-to-volume ratio, which predisposes these dogs to hypothermia during anesthesia; (3) hematological differences such as a higher packed cell volume and lower serum protein compared with other dog breeds which may complicate interpretation of preanesthetic blood work; (4) Impaired biotransformation of drugs by the liver resulting in prolonged recovery from certain intravenous anesthetics, especially thiopental; and increased risks of drug interactions. Safe anesthetic management of sighthounds should include sedative premedication and appropriate use of analgesic drugs to minimize perioperative stress. Thiopental, or any other thiobarbiturate, should not be used in these dogs. Propofol, ketamine/diazepam combination, and methohexital are recommended alternative intravenous anesthetics. Avoid coadministration of agents that inhibit drug biotransformation, such as chloramphenicol. Inhalation anesthesia using isoflurane is the preferred anesthetic maintenance technique. Core body temperature should be monitored closely and techniques to minimize hypothermia should be employed both during anesthesia and into the recovery period.     

Urine production,renal function,and drug monitoring in the equine intensive-care unit

Monitoring urine production, renal function, and drug concentration in plasma can be extremely valuable in the management of critically ill horses. Renal failure, either hemodynamically-mediated or nephrotoxic, is a very common problem in horses either at admission or during critical care treatment. Prompt treatment is required in order to prevent the renal failure from becoming a life-threatening problem. Drug monitoring is not only used to decrease the risk of nephrotoxic renal failure, but should be used to confirm that therapeutic blood levels of a drug are present. Monitoring therapeutic but less than toxic levels is particularly important in critically ill horses since the pharmacokinetics of many drugs is affected by the degree of illness.     

Anesthesia in the Llama

Anesthesia for llamas is similar to other domestic species, although adjustments in technique are required to allow for species variations. Xylazine (0.4-0.6 mg/kg) is well tolerated for sedation. The thiobarbiturates (8-10 mg/kg), ketamine (2.5-5.0 mg/kg), or combinations of guaifenesin and thiobarbiturates or guaifenesin and ketamine (to effect) can be used for induction of anesthesia. In juvenile or debilitated animals, anesthesia can be induced with halothane or isoflurane administered by mask. After tracheal intubation, anesthesia can be maintained with the inhalation agents, usually halothane or isoflurane. Supportive therapy and many anesthetic monitoring techniques used in domestic animals can be used in llamas. While under marginal planes of anesthesia, llamas can have more active physiologic responses to pain, including bradycardia and vasoconstriction, than domestic animals. Llamas are more prone to airway obstruction after tracheal extubation than domestic ruminants but otherwise recover as well from general anesthesia as domestic ruminants.