Anesthesia; Pain Management
6th Annual Gulf-Atlantic Veterinary Conference
Sheilah Robertson, BVMS (Hons), Ph.D., DACVAA, DECVAA, DACAW, DECAWBM (WSEL), CVA, MRCVS
Senior Medical Director
Lap of Love Veterinary Hospice
Caesarean sections (C-sections) are performed for many reasons in dogs and cats, and may be an elective or emergency procedure. The outcome for both the dam and the offspring should be positive if you are well prepared, understand the physiologic changes related to pregnancy and their impact on anesthetic management, and have a neonatal resuscitation protocol in place. A successful C-section is a team effort and should be a rewarding experience rather than a stressful ordeal. Mortality rates for dams and offspring have decreased over the years due partly to improved anesthetic management and the introduction of new anesthetic agents. The physiologic changes that occur during pregnancy are well documented in humans and these changes are assumed to occur in dogs and cats but not all are documented. Changes occur in the hematologic, cardiovascular, respiratory and gastrointestinal systems and these have an impact on anesthetic management. Brachycephalic dog breeds have the highest C-section rate. Pedigree cats have a higher likelihood of dystocia than mixed breeds, with conformation (dolicocephalic and brachycephalic) increasing the likelihood of a C-section. Historically a wide range of maternal death rates have been reported but recent data suggests a zero-mortality rate is possible. Survival rates in offspring have increased over the years and are higher if the C-section is planned and the dam is not a brachycephalic breed. The need for premedication will depend on the status and temperament of the dam. A C-section is a major surgery and analgesia is required. The advantage of administering opioids prior to, or at induction of anesthesia is that they will reduce the requirements for induction and inhalant agents resulting in greater hemodynamic stability. In many cases they may be withheld until after delivery of the offspring but should be given prior to recovery. Infiltration of local anesthetics prior to incision and at closure is easily and quickly performed. Non-steroidal anti-inflammatory agents can be used in stable patients, but should not be used in dehydrated or hypotensive animals. Mask induction with an inhalant agent should be avoided as this is associated with greater mortality and increases the risk of aspiration. Ketamine has been linked to neurologic depression in puppies and should be avoided. Propofol has been widely used and associated with better neurologic scores in puppies when compared to the use of thiopental. More recently, alfaxalone has been compared with propofol as an induction agent in dogs undergoing C-section. Compared to propofol Apgar scores (a measure of neonatal vitality) were higher at 5, 15 and 60 minutes after delivery in puppies whose dams received alfaxalone.