Anesthesia in the domestic rabbit is often perceived as a high-risk procedure. Studies show the perianesthetic mortality rate for rabbits is significantly higher than for common companion animals, estimated around 1.39% within 48 hours of the procedure. This is almost ten times the risk reported for dogs or cats, highlighting biological differences that require specialized veterinary care. The procedure involves pre-anesthetic sedation and pain control, induction, and intense monitoring. When performed using modern protocols and experienced staff, the risks are substantially mitigated, but they are not eliminated.
Understanding the Unique Risks of Rabbit Physiology
The physiology of rabbits makes them uniquely susceptible to complications under anesthesia. Rabbits are obligate nasal breathers, meaning they cannot easily breathe through their mouths, and any obstruction or swelling in the nasal passages can quickly become life-threatening. Their relatively small lung capacity and fragile rib cage also make them prone to respiratory depression from anesthetic agents.
The gastrointestinal tract presents another major vulnerability because rabbits cannot vomit. Their digestive system relies on continuous food intake and motility. Any interruption to this process, such as from stress, pain, or certain drugs, can rapidly lead to a life-threatening condition known as gastrointestinal (GI) stasis or ileus.
As a prey species, rabbits possess a stress response that can be detrimental. Fear or anxiety can trigger an extreme “fight or flight” response, which may cause a sudden release of stress hormones leading to cardiovascular collapse or shock. This high metabolic rate also makes them susceptible to rapid changes in blood glucose levels, increasing the risk of hypoglycemia during the anesthetic period.
Furthermore, the rabbit’s unique metabolism affects how they process certain medications. Approximately 30 to 50% of rabbits possess an enzyme called atropinase, which rapidly breaks down the anticholinergic drug atropine. This renders the drug ineffective for reducing salivary secretions or counteracting a slow heart rate, necessitating the use of alternative agents like glycopyrrolate.
Essential Pre-Anesthetic Preparation
Minimizing stress is a step in pre-anesthetic preparation, as it directly impacts the patient’s physiological stability. Rabbits should be kept in a quiet, warm environment away from predatory species like dogs and cats while awaiting their procedure. Gentle handling and the use of familiar bedding or carriers can help reduce the anxiety that precedes induction.
Unlike other species, rabbits must not be fasted before anesthesia due to the risk of triggering GI stasis. While a prolonged fast is avoided, some protocols recommend withholding food for one to four hours immediately prior to induction to ensure the oral cavity is clear of food residues that could be inhaled during intubation. Water should remain available.
Pre-medication is a routine practice to stabilize the patient and reduce the required amount of general anesthetic. This cocktail typically includes an opioid analgesic, such as buprenorphine, to provide pre-emptive pain control before the surgical stimulus occurs. Sedative or tranquilizing agents like midazolam are included to reduce stress and facilitate smoother handling for procedures like intravenous (IV) catheter placement.
Establishing IV access is crucial for administering induction agents, fluids, and emergency medications. The marginal ear vein or cephalic vein are the most common sites for catheter placement. Fluid therapy is crucial for correcting any pre-existing dehydration and maintaining blood pressure during the procedure.
Anesthetic Agents and Intra-Operative Monitoring
A balanced anesthetic technique is preferred to minimize the dose of any single agent, thereby reducing side effects. Inhalant anesthesia, typically using isoflurane or sevoflurane, is the most common and safest method for maintaining general anesthesia in rabbits. However, induction with gas alone can be stressful and may cause breath-holding or respiratory irregularities.
Injectable agents are often used in combination with inhalants or as the sole anesthetic for very short, minor procedures. A common protocol involves a combination of a dissociative agent like ketamine with a sedative like medetomidine. The use of local anesthetic nerve blocks, such as lidocaine, is integrated into the anesthetic plan to provide targeted pain relief at the surgical site and lower the need for deeper general anesthesia.
Airway management is challenging due to the rabbit’s narrow mouth, large tongue, and limited jaw opening. While intubation allows for precise control of ventilation and oxygen delivery, it requires specialized skill and equipment. Supraglottic airway devices (SGADs) are often used as an effective alternative, as they sit above the larynx to create a seal, providing a less invasive means of securing the airway.
Intensive intra-operative monitoring detects rapid changes in the patient’s condition. Specialized equipment tracks heart rate, respiratory rate, and body temperature. Capnography measures the carbon dioxide concentration in exhaled breath, providing a real-time assessment of ventilation. A Doppler probe monitors blood pressure to ensure stable circulation and prevent hypotension.
Ensuring a Smooth Recovery
The post-operative recovery period requires careful management. Maintaining body temperature is a priority, as hypothermia is a common complication due to metabolic suppression caused by anesthetic drugs. The rabbit must be kept warm using circulating water blankets or forced-air warming devices until their body can regulate its temperature independently.
Continued pain management is another component of recovery, as pain is a major trigger for GI stasis. A multi-modal approach, including injectable long-acting opioids and non-steroidal anti-inflammatory drugs (NSAIDs) like meloxicam, is utilized. Since rabbits are adept at hiding signs of pain, the administration of analgesia is preemptive and continued for several days post-surgery.
The immediate return to feeding is paramount for stimulating gut motility and preventing ileus. As soon as the rabbit is awake and able to swallow, they should be offered their favorite foods, such as hay and fresh herbs. If the rabbit is reluctant to eat, syringe feeding with a high-fiber recovery formula must be started immediately to maintain gut function.
Owners must monitor for signs of post-operative complications, particularly changes in appetite and fecal output. A decrease in the number or size of fecal pellets or a complete absence of droppings can indicate the onset of GI stasis and requires immediate veterinary intervention. Providing a quiet, secure, and familiar environment at home also helps to reduce stress and promote a rapid return to activity.