Pain in Rabbits

Pain is defined as an unpleasant sensory and emotional experience associated with actual or potential tissue damage. It is not well understood, either in humans or other animals. Since it is complex and cannot be measured directly, pain is subjective. I’m sure you can think of two people who might undergo the same unpleasant experience, but each will have a different description of the pain. We assume that as each person interprets pain differently, each individual animal also experiences pain differently. Animals cannot communicate with us verbally, making it especially difficult to identify, classify and quantify their pain. Yet the anatomic and chemical pathways of pain and its perception are similar in all animals. Therefore we work with the premise that conditions that are painful to a human are also painful to animals, such as our rabbits.

Because rabbits can’t talk to us, caregivers and veterinarians have traditionally relied on the observation of pain-induced behaviors to decide when it is time to intervene. We interpret pain as an indication that there is an underlying problem, and in the past, the approach was to correct the problem and assume that the pain would then resolve. The current thinking is that we want to be sensitive to the subtle signs of pain, because the treatment of pain itself can aid healing. It is not only rabbit owners and veterinarians who are changing their attitudes. Human infants are similar to rabbits in many ways, because they also communicate in ways that can be obscure and challenging for parents and doctors to understand. Professionals in both pediatric and veterinary medicine are learning that subtle changes in behavior may be the only indication that an animal or child is in discomfort. Pain is being actively studied in both human and veterinary medicine over the past 15 to 20 years.

Researchers in veterinary medicine are asking questions such as:

1) How can we recognize signs of pain in our patients?
2) What types of benefits are associated with adequate pain control?
3) How can we differentiate pain from anxiety?
4) What types of drugs are effective in alleviating pain?
5) How do different types of animals respond to different treatments?

When working with rabbits, the practitioner must infer the presence of pain by observing changes from normal behavior. A normal rabbit is bright, alert, active, inquisitive, has a smooth coat and good body condition. Pain may be evident as a limp or a change in gait, withdrawal or protection of an injured part, awkward or abnormal postures, licking, rubbing or scratching at an area, or indicated by decreased food and water intake. It is important to know that rabbits evolved as a prey species, an animal that normally needs to hide any handicap in order to escape predation. Signs of pain may be subtle, such as an increase in respiration, reluctance to move, sudden aggression, persistently squinting the eyes, a loss of interest in the surroundings or an inability to rest or sleep normally. If there is abdominal pain, a rabbit may sit in a hunched posture. A rabbit with sore feet may lie stretched out, however a rabbit stretched out with feet kicked back can also be showing that he is content and relaxed. Loud tooth grinding can indicate pain, particularly if it is associated with the other signs listed above. However, rabbits can normally exhibit quieter, infrequent tooth grinding as a sign of contentment. It is unusual for rabbits to vocalize, but when they experience sudden pain or anxiety they may give a high-pitched squeal, quite unnerving to any person hearing it. Very often the presence of pain in rabbits is under-diagnosed by both caregivers and veterinarians, and when it is recognized it is often underestimated. It is very difficult to differentiate pain from anxiety in rabbits, especially since they are often combined and may be manifested by similar changes in behavior. Differentiating pain from anxiety may be simplified by a basic acceptance that rabbits will be anxious whenever they are placed in an unfamiliar environment.

Veterinarians were taught for many years that animals needed a certain level of pain when there was an injury, or post-surgically to prevent the pet from further injuring himself by moving around too much. However, we now know that excessive pain can be detrimental, and even life-threatening in animals, particularly the prey species. Current medical thinking has led practitioners to try to understand and minimize the detrimental effects of pain. Excessive pain can prolong recovery time from illness or injury. It can cause a rabbit to stop eating, with the consequence being a slowing and eventually shut down of the gastrointestinal tract and death. Rabbits in excessive pain also can go into shock and die within 24 to 48 hours despite the fact the illness or injury itself may not have been life-threatening.

We still have a long way to go both in evaluating pain in rabbits and in effectively managing it for their benefit. Human medical researchers have tried to document the benefits of pain control. Most of the veterinary studies have looked at dogs and cats because these are the most common animals brought to veterinary practices. Some of the benefits of pain control include improved breathing functions, decreasing stress responses surrounding surgery, decreased length of hospitalization, faster recovery to normal mobility, improved rates of healing and even decreasing the spread of cancer after surgery. Almost all studies show people and animals return to normal eating and drinking habits sooner when given relief from pain. Therefore prevention, early recognition and aggressive management of pain and anxiety should be essential to the veterinary care of rabbits. Rabbit owners are justified in requesting support from their veterinarian on this issue. It is a good idea to assume that any invasive surgery can potentially be painful for a rabbit. Rabbits tend to return to eating and recover faster following spay and neutering surgeries when provided an analgesic to relieve pain during the surgery and for at least 24 hours following the surgery.

Pain is only one of many stress factors that sick rabbits must face. Sick rabbits need to cope with their disease or injury in addition to stressful changes that come with the problem. A sick rabbit usually has to leave his familiar surroundings and travel to the veterinary hospital, a strange environment with threatening noises and smells. He may also be separated from his human and/or rabbit friends. The veterinarian, usually a stranger to the rabbit, palpates, pokes and moves painful parts of the rabbit’s body. The doctor may need to restrain him and take blood or perform other diagnostic procedures. We need to try to see the environment from the rabbit’s perspective. We can reduce frightening and/or painful aspects of a procedure by petting the rabbit, speaking in soft tones, using good nursing practices and providing a home and hospital environment that is conducive to making the bunny feel safe and reducing anxiety. Rabbits respond better and may recover faster if returned to their familiar home environment as soon as possible. It is a strongly held belief by many rabbit owners that rabbits are comforted by being with a familiar companion rabbit whenever possible during a veterinary hospital stay. However, caregivers must also listen to the veterinarian’s decision because there are occasions that warrant keeping the rabbit alone for observation and sample collection.

Analgesia literally means absence of pain sensation. The realistic use of analgesia is meant to relieve pain and discomfort through medication. There is not one drug that abolishes pain without complete anesthesia or loss of consciousness. Unfortunately, not all medications work exactly the same in every animal or human. This makes it difficult for the veterinarian to determine how effective or even how long a treatment may be effective in an individual. Treatment may involve many different levels of providing comfort.

When a rabbit needs to be hospitalized, the veterinarian may choose to give medication to reduce anxiety, such as midazolam. Rabbits require high dosages of this type of drug and may appear quite drowsy, yet when they are moved or examined, they become very alert. Your veterinarian will assess your rabbit and his disorder prior to prescribing any medication. There are no drugs developed specifically for rabbits, but many analgesics have been evaluated for rabbits, and dosages are available. There are several different categories of medication to control pain, and these will be briefly described:

  • Local anesthetics, such as lidocaine, provide excellent analgesia provided that the local block is given over the entire surgical area. Veterinarians use local anesthetics for minor surgical procedures such as skin biopsies, or they can be used in the immediate area of surgical incision as a supplement to general analgesia.
  • Non-steroidal anti-inflammatory drugs (NSAIDS), such as aspirin, carprofen, flunixin meglumine, and meloxicam are able to decrease swelling and inflammation. The potency of different NSAIDS varies with each drug, dose and type of pain. Rabbits require high dosages of aspirin, but it can be a very effective analgesic. It can be administered at home, but should be used only under veterinary supervision. Caution should be exercised if NSAIDS are used for very long time periods because they may produce negative side effects in the gastrointestinal tract and the kidneys. When rabbits require NSAIDs for chronic conditions such as arthritis, the veterinarian may want to re-examine and take blood from the rabbit to make sure these organs stay healthy.
  • Alpha-2-Agonists, such as xylazine, are powerful analgesics especially for the treatment of abdominal organ pain. But these drugs also produce deep sedation and depression of the heart rate and blood pressure. Therefore, this type of drug is not often used for relief of pain after surgery, although it can be used as part of the surgical anesthesia drug combination.
  • Narcotics include a diverse group of drugs in the opioid family. Opiods are the strongest and most effective analgesics for the treatment of pain but there are well-known side effects and disadvantages. Veterinarians often use narcotics for rabbits just prior to surgery, during surgery and immediately following surgery. Most opioid drugs are controlled by the Federal Drug Administration and can be difficult for veterinarians to prescribe for home use.

Your veterinarian should be able to recommend an appropriate plan to alleviate your rabbit’s pain once a diagnosis has been made. Do not try to develop your own home remedies for pain relief. Each medication has side effects that could be very dangerous for your rabbit. As a caregiver, you can do a number of things to minimize your rabbit’s discomfort such as careful handling of the sick rabbit, prompt communication with your veterinarian, gentle nursing care and rest to improve your rabbit’s comfort, access to food and water and a palatable diet to keep the rabbit eating. It is important to prevent changes in gastrointestinal motility especially when the rabbit is already stressed by disease.

by Joanne Paul-Murphy, DVM, Dipl. ACZM 
*Reviewed and approved by the HRS Health Committee 9/06