Hind Limb Weakness in the Rabbit
There are many diseases that can affect the neurological state of a rabbit. It is often necessary to perform one or more diagnostic tests to determine the cause. If rabbits become weak or paralyzed, it affects their ability to eat daily the nutrient-rich cecotropes from their digestive tract. These cecotropes may collect on the anal area or become less solid. This can further affect the rabbit’s general health on top of whatever disease is already contributing to the weakness.
We will look at a list of some of the more common diseases that can result in paralysis or weakness of the pet rabbit. This article is not designed to be a complete list of all possible diseases. Remember, please find a knowledgeable rabbit veterinarian BEFORE you need one! If you do not know where to look, to find a referral consider contacting a local rabbit club or group, the National House Rabbit Society or go to the Association of Exotic Mammal Veterinarians. Have your rabbit examined while he is still healthy and establish a place to go when your bunny is not feeling so well. This could be a life saver!
Spondylosis of the Lumbar Spine
Cause - This is a fairly common disease of rabbits over 4 years of age, particularly females of medium to large breeds. The vertebrae in the lumbar (lower back) area gradually develop small bony protrusions (spurs) that can eventually bridge to the adjacent vertebrae, resulting in the fusion of the two together. The exact reason this happens is unknown, but it is likely an aging process. It can be aggravated if a rabbit is overweight or perhaps has not had adequate exercise during her life. This disease is not life threatening and can progress slowly for years.
Signs - The fusing of the vertebrae decreases the spine’s flexibility and prevents the rabbit from being able to jump and run as easily. Before these bony spurs fuse completely, they can rub against each other and cause pain. The pain can come and go, dependent on things such as the weather and how much exercise the rabbit got the day before. Rabbits severely affected with this disease “shuffle” rather than hop and on some days can become reluctant to move at all. The rabbit may also have difficulty getting in and out of the litter box. Grooming can become a problem when the spine is painful or inflexible and there may be evidence of urine or stool collection around the hindquarters. The bunny may not be able to eat his cecotropes. In addition, rabbits with this condition may not be able to scratch their ears and therefore an excess amount of ear wax may accumulate.
Diagnosis - The diagnosis is based on finding the bony changes on an x-ray of the spine.
Treatment - Since we do not know why this disease occurs we cannot advise on prevention; however maintaining a normal weight and allowing plenty of exercise throughout the pet’s life is beneficial in preventing so many diseases. Once diagnosed, the spinal disease is managed primarily with pain medications, which can include aspirin, nonsteroidal anti-inflammatory drugs (NSAIDs), other pain medications, and in some advanced cases, corticosteroids. Corticosteroids should always be used with caution in rabbits as long-term use may result in gastrointestinal upset. All these medications should be used with caution and only under veterinary supervision. Acupuncture and chiropractic treatments have also provided relief for many patients and reduced the need for or amount of pain medications used. It can be helpful to regularly massage or apply heat to the back. Gentle massage over the muscled areas of the back only, never directly over the bone, can warm the area and help decrease muscle tightness. In addition, if the rabbit is overweight then reduce the workload on the back by reducing the weight. As the disease progresses, it will be necessary to keep the hind quarters clean from urine and stool and to provide soft, absorbent bedding to prevent “bed sores” and pododermatitis (foot pad infections). Check the ear canals at least once weekly for excess wax accumulation and gently clean only the outer area of the ear (no cotton swabs in the ear canal, please!)
Intervertebral Disc Disease (IVD)
Cause – This disease can occur in many species of pets as well as humans. Intervertebral discs are the “padding” located between each vertebrae of the spine. This pad is made up of a tough fibrous capsule enclosing a thick, jelly-like substance. The intervetebral disc acts to absorb shock when the animal is moving and prevent bone from moving against bone. Occasionally the capsule can tear or bulge and put pressure on the spinal cord that runs through the upper part of the vertebrae. That pressure can affect the function of the nerves, starting at the area of the pressure and moving all the way back to the tail. Most often IVD occurs in the back, but can also occur in the neck and over the chest area. It can result from trauma, genetic weakness of the disc capsule, anatomical abnormalities of the spine or for other unknown reasons.
Signs – Signs of IVD depend on what part of the spine is affected and how much pressure is being applied. There may be a mild weakness to a complete paralysis.
Treatment – The treatment of IVD depends on the extent of disease, but will usually include cage rest and the use of anti-inflammatory drugs. In some cases surgery may be necessary to release the pressure on the spinal cord.
Cause: Damage to a rabbit’s back by any kind of trauma can lead to partial or complete paralysis of the hind limbs. The most common cause of back trauma occurs during restraint of a rabbit when he kicks out suddenly or twists. The more forceful the restraint is, the more likely it is that a spinal injury will result. The force of the kicking or twisting can fracture vertebrae in the back, which are then unstable and result in severe bruising or severing of the spinal cord. Rabbits can also sustain this kind of trauma (although rarely) when running or playing. Rabbits who are confined to cages and not allowed daily periods of exercise are at an increased risk for trauma due to decreased bone density.
Signs: Complete or partial paralysis is immediately evident after the injury. There may be loss of bladder and bowel control.
Diagnosis: The damaged vertebrae can usually be seen on an x-ray. Occasionally the vertebrae will “snap” out of place during the injury, cause damage to the spinal cord and then go back into place by the time the x-ray is taken. These cases can be difficult to diagnose unless high-detail x-ray film is used or a myelogram is performed.
Prevention: Preventing damage to the spine from restraint is two fold. One is to make sure your rabbit has an hour or more of exercise daily outside of the cage where he can move quickly, or jump up and down off of low surfaces. This will help to maintain bone density. Secondly, learn how to restrain your rabbit properly with a minimum of force. Desensitize your rabbit to being held and handled by gradually teaching him that touch is good; train with treats and use short sessions. Work on the floor for anything that might be particularly scary to prevent injury from jumping off a high surface or out of your arms. If the rabbit is struggling a lot, then release him, let him get calm, and try again with less restraint.
Treatment: If the spinal cord is completely severed or seriously bruised, there is no treatment that will return normal neurological function. Euthanasia should be considered for these patients because their quality of life will be poor. Rabbits who have only mild to moderate damage to the spinal cord or who still have sensations in the toes and maintain bladder or bowel control have a chance of healing. These rabbits should be confined to a cage for a period of 6 to 8 weeks to facilitate healing the fractured bones. Corticosteroids may be used for the first few days after the injury. Many of these rabbits will regain at least partial if not total neurological function and live a fairly normal life.
Cause – Encephalitozoon cuniculi is a one-celled organism called a microsporidian that can infect rabbits. Adult rabbits are infected by either ingesting or inhaling the spores (the reproductive part) passed in the urine of animals with active disease. However, the majority of rabbits become infected from their mother through the placenta during pregnancy. After entering the body, the infective spores pass through the intestine and then move throughout the body to the heart, lungs, liver and spleen. At this point in the disease most rabbits show no outward signs of illness. In some rabbits, however, E. cuniculi will eventually spread onward to the kidneys, eye, brain and spinal cord. Even at this stage, many rabbits will show no signs of disease and live normal lives. Others, however, can have serious consequences, including death, if the infection overwhelms their immune system.
Signs - Fortunately most rabbits affected with this parasite remain completely normal throughout their lives. However, some rabbits develop mild to serious disease. It is unknown why some rabbits develop clinical disease and others do not, although it might depend partially on genetics. Certainly animals who are immunocompromised are at a higher risk.
If the brain or spinal cord is infected, the signs may vary depending on what area is damaged. A rabbit may experience any one or combination of the following: unilateral or bilateral facial paralysis, weakness in only one limb, complete hind limb weakness or paralysis, all four limb weakness or paralysis, head tilt, loss of appetite, behavior changes, depression, seizures (mild to severe) and sudden death.
Diagnosis and Treatment - It has been extremely difficult to demonstrate a definitive correlation between neurological disease and active E. cuniculi infection. Serological testing (blood testing for antibodies to an organism) for E. cuniculi has some value but is not definitive and, if not interpreted appropriately in the light of its shortcomings, may be misleading. The only way to diagnose E. cuniculi as the definitive cause of neurological disease is to take brain or spinal cord tissue samples while there are clinical signs and find the organism and its damage in the microscopic samples. It is difficult to prove this correlation because a brain or spinal cord biopsy is dangerous for the rabbit and the E. cuniculi organism can be difficult to find in nervous tissue. A presumptive diagnosis can be made based on ruling out other disease and looking for additional signs coming from the brain or spinal cord. Having said all this, if a rabbit shows signs compatible with brain or spinal cord disease, has a positive test for E. cuniculi, and other diseases have been ruled out, some veterinarians will choose to treat for E. cuniculi empirically.
Proper and effective treatment for E. cuniculi is controversial because in an illness where the definitive diagnosis is almost always made after death, properly evaluating therapeutic protocols for effectiveness and comparing them against other treatment protocols is almost impossible. Additionally, there are very few science-based data showing a clear correlation between treatment protocols and alleviation of signs. The majority of reports to date are anecdotal, based on clinical signs that could have changed with or without a drug in place. It is fairly well accepted that at this time there is no drug that will clear an animal completely of E. cuniculi once an infection is established, but treatment may stop progression and reduce clinical signs. Further complicating research into treatment, some rabbits may be able to recover spontaneously (without the benefit of treatment) from E. cuniculi infection. This makes it even more difficult to explain clinical improvement by the use of medication. Some cases improve because the rabbit’s immune system effectively cured it. Some of the medications that have had been used to treat infection with E. cuniculi include albendazole, fenbendazole and oxibendazole.
Rabbits that are allowed free unsupervised access to their surroundings can come in contact with a wide variety of toxic substances. Toxic materials can include some plants, rodenticides, insecticides, human medications, antifreeze and heavy metals. Heavy metal such as lead and zinc can be found in old house paint, old metal cages, jewelry and old stained glass products to name a few.
Signs – The signs are variable depending on the toxin and how much was ingested. Rabbits do not have the ability to vomit so once they take in a toxic substance they are unable to remove it from their body quickly. Signs seen may include any one or combination of lethargy, rapid breathing, loss of appetite, weakness, paralysis and collapse.
Diagnosis – The diagnosis of toxicosis depends on a number of factors including the history of exposure, blood tests to determine abnormalities and x-rays to detect metallic substances in the gastrointestinal tract. Any information you can give regarding the rabbit’s environment and history of the signs is probably the most important factor in determining the cause of the disease.
Treatment – The treatment is based on the toxin ingested. The effects of many toxins can be reversed if caught in time.
Cerebrovascular Accident (CVA or “Stroke”)
Cause: CVAs occur in pets as well as in humans. A CVA is caused by either an obstruction of the flow of blood through a blood vessel in the brain (such as with a blood clot) or when a blood vessel ruptures and bleeds out into the surrounding brain tissue (as can occur with an aneurysm). Both “vascular accidents” can cause mild to severe brain tissue death. Occasionally, an animal can have a stroke following a surgical procedure due to a blot clot that gets lodged in a blood vessel in the brain.
Signs - The signs depend on where the damage took place in the brain and may range from mild facial or extremity muscle weakness to complete paralysis of one or both sides of the body. Sudden death can also occur. The incidence of CVAs increases both in animals and people with age.
Diagnosis - It is difficult to diagnose a CVA in an animal without the sophisticated equipment available to humans. In humans, a diagnosis of CVA is made with one or more of the following procedures: arteriography (a radiographic dye study of the brain’s blood vessels), CT (computed tomography) scan or MRI (magnetic resonance imaging). In animals a diagnosis of stroke is usually suggested based on ruling out other causes of disease. In some areas CT and MRI diagnostics are available for your pet.
Treatment - There is no specific treatment for a CVA. The only thing that can be done is to support the pet with fluids, assist feedings and pain medications if necessary. Blood thinning medications are used in humans and may be used in your pet if the CVA was caused by a blood clot. If the rabbit has lost the ability to control his bathroom habits, then he will have to have his bladder expressed several times a day and kept clean and dry. It can take weeks to months for the nerve tissue to heal and usually there is some degree of irreversible brain damage. You should discuss your bunny’s prognosis with your veterinarian and decide what the most humane course of action should be for your pet.
Cause - Other than the high incidence of uterine cancer in female rabbits over two years of age, neoplasia of other organs is less common in rabbits than in other species such as humans, ferrets and dogs. The next most common cancer of rabbits is lymphoma that can develop anywhere in the body and at any age. This cancer has been found in the spinal column where it causes damage to the spinal cord and the surrounding bone. Other malignant cancers, such as uterine adenocarcinoma, can spread all over the body including the bony spinal column. Primary bone cancer has also been seen in the rear legs of rabbits, which also leads to hind limb weakness.
Signs - The signs of cancer can be variable depending on the tissues being affected and may develop gradually or may appear suddenly.
Diagnosis - A diagnosis of cancer may be suspected on an x-ray and then confirmed with a biopsy of the affected tissue. Cancer in the brain or spinal tissue is more difficult to detect.
Treatment - Chemotherapy can be attempted if it is appropriate for the particular cancer. Another option is radiation therapy if there are such facilities in your area. If the cancer is in an extremity, it may be possible to amputate the limb to save the rabbit. Corticosteroids can sometimes slow the growth of the cancer and can be used to prolong life for a while.
Any disease that causes a rabbit to feel weak can cause hind limb weakness and can be confused with a true neurological disease. Bunnies who are anemic or have heart disease, for instance, will not be able to get enough oxygen to their brain or muscle tissue and may appear weak and wobbly, particularly after exercise. Rabbits with liver or kidney disease can develop a buildup of metabolic toxins in their blood that interfere with normal brain and muscle function, and thus lead to weakness. Malnutrition or a severely imbalanced diet can also lead to a generalized weakness. For instance, a lack of sufficient vitamin E can lead to a type of muscular dystrophy and the inability to move properly. Heat stroke and moderate to severe respiratory disease can also lead to weakness.
Any disease of a rabbit that causes pain on movement may be incorrectly interpreted as hind limb weakness. For instance, pododermatitis (ulcerated feet) causes pain on movement, therefore the rabbit may sit hunched all day in his cage and appear unable to walk.
Arthritic conditions of the spine, hips, knees or hocks can cause an inability to move normally. Rabbits who are experiencing an intestinal shutdown from an obstruction, disease or inappropriate diet are often immobile due to the pain of the gas-filled intestinal tract and are ultimately weakened by the disrupted blood electrolyte balance.
The diagnosis of any of these diseases depends on a combination of a good physical exam and history, and various diagnostic tests. The treatment, of course, depends on the diagnosis.
Other diseases can also lead to generalized or hind limb weakness in the rabbit:
Home Care of the Weak Rabbit
Rabbits with hind limb weakness will need special care. Some considerations you will need to make include:
by Susan Brown, DVM
Date Published: 3/7/2001
Copyright 2011 – 2012 by Susan Brown, DVM. Used with permission. All rights reserved
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