MEDICAL CONDITIONS
Females
A leading cause of death in the female rabbit is a cancer of the uterus called adenocarcinoma. This is a malignant disease, and unfortunately, once it is diagnosed, it has may have spread to other areas of the body. This cancer is preventable by having your pet spayed between 6 months and 2 years of age. The spay procedure involves removal of the bunny's uterus and ovaries and also helps to prevent the occurrence of breast cancer later in life.
Males
Some male bunnies, especially the dwarf varieties, may become extremely aggressive when they reach sexual maturity. There may be excessive biting and spraying of urine outside of the regular litter box area. The urine may develop a very strong and unpleasant odor due to the presence of male hormones, and these little boys may not groom themselves well, developing stained and messy tail areas. These males may start attacking other rabbits, leading to serious bite wounds. The best solution to these behavioral problems is castration (surgical removal of the testicles). This procedure is recommended any time after 5 months of age.
Overgrown teeth
Overgrown incisors (the front teeth) are usually caused by a congenital defect. Other causes can be injury or trauma to the teeth, infection in the roots of the incisors, or malalignment or infection in the molars (the back teeth). Rabbits' teeth grow continuously throughout their life. If the incisors or molars are not lined up properly then they do not get worn down which results in overgrowth. Overgrown teeth can cause mouth infections, ulcerations of the lips or tongue and inability to pick up and eat food. The most common treatment for these overgrowths is to have the teeth cut periodically (every 3 - 8 weeks). We do not recommend the use of nail trimmers for this procedure, because it can easily result in the fracture of the incisor deep under the gum with the potential for subsequent gum infection. Your veterinarian will use a special instrument to trim the teeth more safely. If the molars are involved, or if the animal is very skittish, a general anesthetic may be required for the teeth trimming procedure. A permanent cure for overgrown incisors is the complete removal of the incisors under a general anesthetic. Rabbits are able to eat normally afterwards and teeth trimming will obviously no longer be necessary. If your pet has teeth problems, please discuss the options with your veterinarian.
Loss of Appetite
There are a variety of reasons why a bunny will lose his appetite. The most common reason in our experience is a diet low in fiber and high in calories. This combination can lead to obesity, fatty liver disease, sluggish movement of the intestinal tract, and accumulation of hair and food in the stomach which then makes the rabbit not feel like eating. When the rabbit doesn't eat, then the intestinal tract stops moving and the problem escalates. We consider 'hairballs' to be a symptom of other problems (usually a poor diet) and usually not a primary disease in itself. Angora breeds which have very long hair, may be an exception to this rule, because the length of their hair may make it difficult to pass. Another common condition that can cause appetite loss is dental disease. Overgrown molars that have sharp edges which lacerate the tongue and abscesses of any of the tooth roots can cause a pet to cease eating due to pain. Less common, but very serious conditions that can also lead to appetite loss include uterine infections, abscesses, respiratory infections, gastrointestinal infections, middle ear infections, eating toxic materials and bladder and kidney infections. Loss of appetite is something that should be investigated by your veterinarian within 48 hours even if the pet is acting normally. Rabbits rapidly develop a deteriorating condition of the liver when they go without food for long periods of time. If the liver deteriorates excessively, there may be no way to reverse the process. Early diagnosis and treatment of appetite loss is the best way to save your pet's life.
Pasteurellosis
A large percentage of rabbits harbor a bacteria in their sinuses called Pasteurella multocida. This bacteria doesn't cause a problem in most bunnies with a healthy immune system. However, under certain stress situations, such as poor diet, high environmental temperatures, poor air circulation, overcrowding, moving, etc., this bacteria can reproduce rapidly and cause potentially serious disease. This bacteria may cause infections of the upper respiratory tract. uterus, skin, kidney, bladder, tear ducts, middle ear or lungs. Please have your pet examined if you observe any discharges around the eyes, nose or anal area, or if there is a loss of appetite, depression, diarrhea, head tilt, loss of balance, or labored breathing. NEVER attempt to use antibiotics without veterinary supervision. Your pet's gastrointestinal tract is an extremely delicate organ, dependent on large populations of healthy bacteria to digest the food. If inappropriate antibiotics are given indiscriminately, death may result because the antibiotic killed the normal bacteria in the gut which led to an overgrowth of deadly bacteria.
Snuffles
Human colds and flu are caused by a variety of viruses. Rabbits do not contract human viruses and their 'cold' or upper respiratory signs are usually caused by bacteria. The most common bacteria involved is Pasteurella multocida, which is commonly referred to as 'snuffles' because there may be nasal discharge and sneezing. However, we must remember that not all upper respiratory diseases are caused by Pasteurella , or there may be other bacteria involved in addition to the Pasteurella. Two other bacteria commonly encountered are Staphylococcus and Bordetella. There are a variety of reasons why a rabbit may develop an upper respiratory infection including: poor diet (which can lead to a variety of problems including a poorly functioning immune system), poor ventilation (for example in a basement that might be damp with still air), poor sanitation, genetically weak immune system and exposure to other rabbits with serious upper respiratory disease. There are, however, rabbits that are in healthy environments that still may develop upper respiratory disease. Some rabbits may harbor any of these bacteria in their sinus area for months or years without a problem and then suddenly 'break' with disease. Rabbits can exhibit a variety of signs that are often lumped together when referring to a 'cold' or 'snuffles'. Most commonly rabbits will exhibit either one more of the following: frequent daily sneezing along with a nasal discharge (usually white and in small chunks), excessive tear production which spill onto the face(the tears may be 'milky' in color), crusty fur on the inside of the front legs (due to wiping the nose with the front paws). The behavior of rabbits with upper respiratory disease may range from totally normal to depressed, heavy difficult breathing (if the bacteria invades the lungs and causes pneumonia) or a loss of appetite, which may be due to in part to an inability to smell the food and pressure in the sinuses causing a 'headache'. If you see your rabbit exhibiting any of the signs described, I would recommend a trip to the vet for treatment. Although most rabbits will only exhibit mild disease and it may not interfere with their daily habits, the problem may become chronic and deep-seated and the longer one waits for treatment, the more difficult the treatment will be. We find that prompt early aggressive treatment is the most effective for long term resolution of the problem. When you visit your vet there are several things that may be recommended above and beyond the physical examination and evaluation of the home environment and diet. A culture taken deep from the nasal sinuses or from a tear duct flush is recommended to determine what bacteria are involved and what would be the best antibiotics to use to treat the problem. Culturing is a relatively painless procedure and does not require sedation, and it can be VERY valuable in treatment success. If your pet is having a problem with excessive tearing, it may be recommended that the tear ducts be flushed. This is a painless procedure usually done with the pet awake with a local anesthetic drop used in the eye. It helps to open up tear ducts clogged with debris so that any eye medication that is used will be better able to enter the affected area. Your veterinarian may also wish to perform blood tests or x-rays on your pet if he or she has stopped eating, has lumps or masses around the face, is lethargic or exhibits other serious signs. Treatment will depend a great deal on the condition of your pet, the severity of the disease, the result of the cultures, and the philosophy of your veterinarian. There is unfortunately no one treatment regimen that will cure every rabbit. Some rabbits despite all treatments will always exhibit some signs of upper respiratory disease, but it is mild enough that it doesn't interfere with their normal life style. The most common sign we see persist, although it interferes little with their daily routines, is loud breathing, especially when turned upside down. This is most commonly due to damage to the sinuses which causes diverts the air passing through the area and causes strange sounds. Antibiotics will need to be used in every case and may include both oral forms and eye or nose drops. Some veterinarians may prescribe injectable antibiotics instead of oral due the unavailability of the antibiotic in an oral form or because it is easier to medicate the pet in this manner. We recommend a minimum of two weeks of antibiotics in mild cases and 4 or more weeks in more serious or chronic disease. Remove rabbits that are discharging heavily from the nose from areas where there are other rabbits until the discharge and sneezing is under control. It is ESSENTIAL that the diet be improved with lots of fresh green leafy vegetables, unlimited grass or timothy hay, and limited high fiber pellets. The greens are very high in vitamin C which I feel is beneficial in healing inflamed upper respiratory tissues. Some veterinarians may also prescribe additional oral vitamin C be given once or twice a day to boost the immune system and heal tissue. It is also important that the environment be cleaned up with good ventilation and good sanitation. Clean the litter box regularly to avoid accumulation of irritating ammonia fumes. Install a fan to move the air around and consider using use an air filtering system in the room if your bunny seems sensitive to dust (including hay dust). By working with your veterinarian and a bit of TLC most bunnies with upper respiratory conditions can be helped dramatically.
Gastrointestinal Motility Problems ('Hairball')
The diagnosis of 'hairball' or 'wool block' is commonly made in rabbits. This is a condition that doesn't really exist in the opinion of a growing number of veterinarians who care for rabbits. By that I mean that the primary problem is NOT a hairball, but rather a problem with sluggish motility of the gastrointestinal tract (GIT) leading to dehydration and impaction of material in the stomach and cecum. So how does this happen? One needs to look at the GIT physiology of the rabbit to understand this condition. The indigestible fiber in the diet 'drives' the digestive tract or, in other words, determines the speed with which ingesta moves along. When there is an insufficient amount of this type of fiber present motility may be slowed. Let's take a quick trip through the GIT of the rabbit to look at all the parts. The stomach holds the food and essentially sterilizes it with a pH of 1 to 2. The food then moves out through the small intestine where nutrients are absorbed into the body. At the junction of the small intestine and the large intestine is a large blind sac called the cecum. This is where the digestible fiber and other portions of the diet that need to be fermented are deposited. A variety of microorganisms break down this material in the cecum and convert it into nutrients such as fatty acids, amino acids and vitamins. (Please note that Lactobacillus or Acidophilus are not significant microorganisms in a rabbit's cecum). The nutrient rich material is then excreted in the form of cecotropes (some people call these 'night feces') which are eaten directly from the anus by the rabbit and redigested. When the speed with which material moves through the GIT is altered it can affect how quickly the stomach and cecum empty. If the motility is reduced as in diets that are too low in indigestible fiber, then the stomach and cecum will empty slowly. The rabbit eventually stops eating and drinking probably due to a feeling of fullness in the stomach. When there is no food coming into the system the GIT motility slows to almost a standstill. Water is still needed by the body and it is extracted from the stomach and cecal contents. A vicious cycle is now set up. The longer the rabbit doesn't eat, the more dehydrated and impacted the material in the stomach and cecum becomes and the less the rabbit feels like eating. Add to this a diet too high in protein or starch and the result can eventually be disastrous. Diets too high in protein and/or starch can result in changes in the cecal pH and thus the types of microorganisms growing there. These fragile communities are altered allowing the growth of bacteria such as Clostridium spiriformes which can result in death due to the production of iota toxins. So where does the hair come from? Rabbits will always have some hair in their stomach contents. They groom themselves constantly and swallow the hair. A true 'hairball' is comprised of nearly 100% hair as in the cat or the ferret. In the rabbit, the hair is mixed with stomach contents in a mass. As this material dehydrates, the larger particles are left behind (which includes the hair). The liquid stomach contents gradually turn into a solid tightly adhered mass. The stomach contents feels doughy and firm on palpation. Radiographs reveal a solid mass of material in the stomach, often with a distinctive halo of air around it. To sum it up, the cause of this condition is NOT the presence of hair in the stomach, but rather a GIT motility disorder that RESULTS in firm impacted stomach and cecal contents. If we do not correct the underlying problem, then this condition is destined to reoccur. How do rabbits act when they have impacted stomach or cecal contents? They will stop eating either suddenly or gradually over a period of time. The stools will get smaller and smaller, then stop altogether. Often, these patients will be bright and alert for a week or longer. They may want to chew up the paper on the bottom of the cage, the woodwork or the wall board (all sources of fiber that they are craving), but refuse to eat their pellets. Some rabbits have had periodic soft, pudding-like stools prior to complete anorexia. Eventually these patients can become seriously ill and die if the condition is not treated. How do we treat a stomach impaction due to reduced GIT motility once it happens? It is important to make sure that ALL the conditions that may be affecting the rabbit are detected. Your veterinarian may suggest x-rays or other lab work. Since this is an impaction problem, the goal is to rehydrate the rabbit both through the circulatory system and through the GIT. Fluids are administered either under the skin or in a vein along with high fiber and moisture feedings by syringe or tube. Ground rabbit pellets, powdered alfalfa powder mixed with blenderized green leafy vegetables and an oral electrolyte solution can be used. In addition, medications to stimulate the GIT to start moving again and analgesics are used. It is rarely necessary to use antibiotics and in fact these might cause further disturbance to an already compromised GIT. Some people like to use laxatives, and enzymes. I too, have used these products in the past, but have found that they really aren't necessary. I have equal success in treating this condition with or without enzymes. It is important to remember that enzymes of any kind (pineapple, papaya or pancreatic) DO NOT dissolve hair. But the real keys are hydration of the stomach/cecal contents and getting the GIT moving again. I find that over 50% of the rabbits presented with this condition will take care of it themselves when they are given a big pile of leafy greens to eat. Most of the cases of stomach impaction we see have been on a primary pellet diet and have had little or no access to greens or hay. They are craving fiber and fluids and the leafy greens can be just the ticket. In addition we give all these patients good quality grass hay. We completely remove pellets from the diet (rabbits usually won't eat pellets when they are ill anyway). Whatever treatment is used one can expect stools to be produced within three days. It is extremely rare to have to perform surgery for this condition. Other causes of GIT disease in the rabbit include partial or complete blockages of the intestine with foreign material (often carpet fibers), post surgical adhesions, intestinal parasites, toxins (such as lead) and other systemic disease. It is IMPORTANT to have your rabbit thoroughly examined by your veterinarian to determine ALL the problems prior to instituting the treatment that I have described. So, how do you PREVENT this situation? It really isn't difficult. The nature of the GIT physiology of the rabbit suggests that it is vitally important to provide a diet that is high in indigestible fiber. This is easily provided in the form of grass hay (oat, timothy, bermuda,etc). Grass hay is lower in calcium, protein and calories than legume hay such as alfalfa. Hay should be provided 24 hours a day. This way, the pet will never go hungry, will always have a source of nutrition and fiber. The next important part of the diet are fresh leafy greens. You should use at least three different types a day so as to provide a variety of nutrients and tastes. Examples include dandelion greens, kale, mustard greens, romaine, endive, carrot tops, parsley, etc. In my opinion rabbits can have as much of these foods as they want as long as they are eating the hay well. If you have never fed greens to your pet, it is best to introduce hay first for a couple of weeks and then add in the greens gradually over a few days. In this manner is unlikely that your rabbit will experience any digestive problems. Rarely a rabbit will have a 'reaction' to a food item and produce a soft stool. Just eliminate this from the diet. Other vegetables and fruits can also be given such as apples, pears, peaches, berries, pea pods, broccoli, papaya, mango, kiwi, tomatoes, melon, oranges, etc. Wash all fresh foods thoroughly as you would for yourself. Stay away from high starch foods such as legumes (peas and beans) and grains. Clean water should always be available in a water bottle or heavy crock bowl. You will notice that your rabbit will drink far less water on a diet high in greens than on one that is composed primarily of pellets. For the NONBREEDING house rabbit the least important part of the diet is the pellets. These concentrated food sources were designed originally for rabbits in production (for food or fur) and for laboratory rabbits. They are packed with calories and vitamins and minerals. Nonbreeding house rabbits do not need these extra calories and they produce most of their own vitamins through their cecotropes when provided a diet high in hay and fresh foods. I rarely recommend pellets as part of the diet for these pets unless I am trying to get weight back on a rabbit or in cases where hay cannot be given because it is unavailable or the humans in the household are allergic to it. We have seen hundreds of rabbits (including my own three; a Flemish Giant, a mini rex and a mixed breed) that are in excellent condition on a hay and fresh food diet alone. These rabbits rarely experience GIT disease. It is so frustrating for me in practice to see the same myths perpetuated about 'hairballs' and to see this disease used so often as a primary diagnosis. Let's stop using the term 'hairballs' and replace it with 'stomach/cecal impaction due to reduced GIT motility'. Understand that impaction is not a CAUSE of disease but the RESULT of underlying GIT problems. This condition is 99% preventable with an appropriate diet. It is unnecessary to routinely use laxatives, enzymes and other supplements. Let's stop trying to play 'catch up' treating stomach crises all the time and feed our pets the type of diet they were designed to eat.
Diarrhea
True diarrhea is not common in the rabbit. This is a condition where all stool being passed is in a liquid form. This is usually a very serious condition and should be seen by your veterinarian immediately. Some serious gastrointestinal conditions that result in diarrhea can be fatal in less than 24 hours. What most people refer to as diarrhea, is an intermittent passing of soft liquid or pudding-like stools. The rabbit will also pass normal formed stools. The soft stools may be seen more frequently at certain times of the day (many times overnight) and may have a strong odor and accumulate on the rabbit's fur. The liquid stools are actually the cecotropes (see section on Night Droppings) that are unformed. There are a variety of reasons for this condition, but by far the most common reason is a lack of sufficient fiber in the diet and obesity. Eliminating the pellets from the diet and feeding good quality grass hay only for one to three months may clear up the problem. Consult your veterinarian if your pet has this condition before making any drastic changes in the diet.
Paralysis In Older Rabbits
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. There are also occasions when the diagnosis in only suggested based on ruling out other causes of disease. Let us look at a list of some of the more common diseases that can result in paralysis or weakness of the pet rabbit.
Spondylosis Of The Lumbar Spine
This is a fairly common disease of rabbits over 4 years of age, particularly females of medium to large breeds. Cause: The vertebrae in the lumbar or back area gradually develop little bony protrusions that can eventually bridge to the adjacent vertebrae resulting in the fusion of the two. No one knows the exact reason this happens, but it is likely an aging process. It can be aggravated if a rabbit is carrying excess body weight (obese). This is not life threatening and can progress for years. Signs: The fusing of the vertebrae decreases the flexibility of the spine and prevents the rabbit from being able to jump and run as easily. Before these bony 'spurs' fuse completely, they can rub on each other and cause some pain. The pain may come and go dependent on things such as the weather and how much exercise the rabbit got the day before. Rabbits affected with this disease 'shuffle' rather than hop and on some days can become very reluctant to move at all. As the disease progresses, it may be difficult for the rabbit to get in and out of the litter box and he may soil himself. Diagnosis: The diagnosis is based on finding the bony changes on an x-ray of the spine. Treatment: There is nothing that can stop the formation or progression of this disease. However, medications can be given to control pain and make the rabbit's life more comfortable. Medications used may include aspirin, nonsteroidal anti-inflammatory drugs, and corticosteroids. All these medications should be used with caution and only under a veterinarian's supervision. Some people have reported that their pet rabbits experienced relief with the use of acupuncture. Many also feel it is 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. If your rabbit enjoys massage, or the application of warmth, then by all means use it. In addition, if the rabbit is obese, it is necessary to reduce the work load 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). Rabbits with any disease that causes weakness of the hind limbs will not be able to keep their ears clean by scratching. Check the ear canals at least once weekly for excess wax accumulation.
Trauma
Damage to a rabbit's back by any kind of trauma can lead to partial or complete paralysis of the hind limbs. Cause: The most common cause of back trauma is when a rabbit is being restrained and it kicks out suddenly or twists. Even when the best restraint is used, it is still possible for this situation to occur. The force of the kicking or twisting can literally fracture vertebrae (spinal bones) in the back. The fractured vertebrae are then unstable resulting in severe bruising or severing of the spinal cord. Rabbits can also sustain this kind of trauma (although rarely) when running or playing. Signs: Complete or partial paralysis is immediately evident after the injury. There may be a loss of bladder and bowel control. Diagnosis: This condition is diagnosed by demonstrating the damaged vertebrae 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 done (where dye is injected into the spinal fluid to determine damage to the spinal cord). Treatment: If the spinal cord is completely severed or seriously bruised, there is no treatment that will return normal neurological function. It is advisable to consider euthanasia for these patients as their quality of life will be very poor. Cases that have only mild to moderate damage to the spinal cord or that still experience some feeling in the toes and maintain bladder or bowel control have a chance of healing. These rabbits should confined to a cage for a period of 6 to 8 weeks to facilitate healing of the fractured bones. It may be necessary to use anti-inflammatory drugs such as corticosteroids 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 good quality of life.
Parasites
The two most common parasites causing neurological disease in the rabbit are Encephalitozoon cuniculi (also known as Nosema cuniculi) and Baylisascaris procyonis.
A. Encephalitozoon cuniculi Cause: This is a protozoal (one-celled) organism in the Microsporidia family that can infect a number of species of animals, including humans. In humans infections are rare except in immunocompromised individuals such as AIDS patients or those suffering from tropical diseases. Some species, such as dogs and cats, either die from the disease or survive the infection and completely clear it from their bodies. In rabbits and mice however, the infection is persistent throughout their lives and may or may not cause obvious signs of disease. Even within species it appears that some genetic strains are more resistant to infection than others. E. cuniculi is passed from infected animals through the urine. The oral route is the most common way it is picked up another rabbit, i.e. when a rabbit eats material contaminated with urine containing infective spores. The spores also can be inhaled and enter the body through the lungs. There is still controversy over whether or not the disease is transmitted through the placenta in the unborn young. The rate of infection in kits is highest when the dam is positive for this disease. Whether this is because the spores are in the environment from previous shedding by the mother or because there is transmission through the milk or placenta has not been definitively determined. Once the spores are in the body, they become 'active' and spread throughout various tissues including kidneys, liver, lung, spinal cord and brain. Microsporidia that infect the kidney go on to actively produce more spores that are then passed in the urine in large numbers within 30 days. The spores are produced for up to 90 days post infection, at which time they stop and the rabbit can no longer infect others. E. cuniculi infections are very common in pet rabbits in the United States. Up to 80% of clinically normal rabbits tested in some populations were positive for this disease. It can not only be transmitted from other affected pet rabbits, but also from wild rabbits and rodents. Signs: Fortunately most rabbits affected with this parasite remain completely normal throughout their lives. However, some rabbits develop serious and sometimes fatal disease. It is unknown why some rabbits develop clinical disease and others do not, although as mentioned previously it might depend partially on a genetics. Certainly animals that are immunocompromised are at a higher risk. The clinical signs in rabbits usually involve disease of the kidney, brain or spinal cord. If severe kidney disease is present, a generalized weakness may be observed which could be initially mistaken for a neurological problem. In addition to weakness and depression, the rabbit may exhibit a poor appetite, increased water intake, increased urination, an ammonia odor to the breath and sudden death. Kidney disease is usually diagnosed by blood tests and occasionally a kidney biopsy. 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: There is a blood test that can detect the presence of E. cuniculi in the rabbit. It detects antibodies to the parasite. The test was primarily designed to detect positive animals in a breeding colony or laboratory setting so they could be removed from the population. The test is of limited use in pet rabbits because it does not prove that this parasite is the cause of the clinical signs present. In other words, many rabbits have been exposed to this parasite and are infected, but will never show any signs of disease. Therefore, if we get a positive test, it only means that the rabbit has the parasite in its body, it does not prove that the parasite is responsible for any of the clinical signs we are currently seeing. The only way to diagnose if the parasite is actually causing the signs would be to take a biopsy of the brain or spinal cord, which is dangerous and not at all practical. Therefore, we can only make a tentative diagnosis of E. cuniculi based on the rule out of other diseases along with the presence of a positive E. cuniculi test showing that the animal has the potential for having a problem with this parasite. Treatment: Unfortunately there is no treatment for an active infection of E. cuniculi. Drugs such as ivermectin and other parasiticides have been tried without success. The parasite lives within the cells and it is very difficult to get medication into this protected area. In Europe there was a study published in 1994 which suggested that the drugs fumagillin and albendazole might be useful, but they are not available in the U.S. and have not been tried on live animals. Even if a drug is discovered that can clear an infection of E. cuniculi, it will not be able to reverse the effects of brain, spinal cord or kidney damage once it has occurred. Rabbits that have clinical signs of disease should be supported with good nursing care. Antibiotics, analgesics and anti inflammatory drugs may be used as needed for secondary problems that may develop. Most pet rabbits have probably contracted the infection from the mother. Rabbits that are obtained as adults and that are not used for breeding are not likely to shed the spores. However, young rabbits under 4 months of age that may have contracted the disease from the mother could be actively shedding the spores in their urine. It would probably be a good idea to isolate rabbits under 5 months of age from other rabbits in the house. An E.cuniculi test could be run on these youngsters to determine if they are carrying the parasite. If they are negative, they could be put with the other rabbits earlier than 5 months of age. We have been unable to find a definitive source that indicates the best product with which to clean the environment and remove any spores. Any materials that are contaminated with urine, such as wood or carpet, that cannot be cleaned thoroughly should be destroyed. Other substances, such as plastic and metal should be scrubbed with a phenol disinfectant (Lysol is one example) or a strong bleach solution and then rinsed thoroughly.
B. Baylisascaris procyonis Cause: Baylisascaris procyonis is the scientific name for a roundworm found in the intestines of raccoons in North America, Japan and Germany. It is estimated that some populations of raccoons have a 68 to 82% infection rate with this parasite. Skunks carry a similar species, Baylisascaris columnaris that can also affect other species of animals. All the things said about the raccoon roundworm will also apply to the skunk roundworm. B. procyonis does not adversely affect the raccoons that carry it. The eggs of the parasite are passed by the millions in raccoon feces where they can stay in the environment for years withstanding heat and cold. When a species of animal other than a raccoon swallows these eggs the microscopic larva hatches out in the intestine and then burrow through the wall of the intestine and begin migrating through the body trying to find a home. The body tries to kill the larva and it moves rapidly to escape attack. The larva seem to have a preference for lodging in the liver, eyes, spinal cord or brain. Occasionally they can be found in other organs. When a larva tries to make a home it causes a great deal of damage as the body tries to either wall it off or kill it. Eventually it dies and is reabsorbed by the body. In very small species such as mice, it might take only one or two larvae in the brain to be fatal. If the larva does not cause significant damage in vital organs then the victim will show no signs of disease. Species other than the raccoon that are affected with this parasite CANNOT pass it on to anyone else. This is the end of the line for the the larva and it never becomes a mature adult capable of producing eggs. There are over 50 species of animals that are affected by this parasite including dogs, squirrels, chinchillas, guinea pigs, mice, rats, birds and humans. This parasite is responsible for disease or death in humans, usually children, every year in this country. Signs: The signs of the disease are similar in all species affected and depend on the amount of damage and the organ(s) affected. Signs can include any combination of the following: sudden lethargy, loss of balance, abdominal pain, paralysis of one or both sides of the body, loss of muscle coordination, head tilt, blindness, coma and death. In humans the signs appear approximately 2 to 4 weeks after exposure. Diagnosis: In humans there are more options open for diagnosis of this disease. There is a blood test to find out if the person has antibodies to the parasite. This is currently not available for rabbits. In humans there is a change in the blood count resulting in a high level of white blood cells called eosinophils. These blood cell also occurs in high numbers in the cerebrospinal fluid (the fluid around the brain and spinal cord). Unfortunately rabbits do not seem to respond consistently in the same way. Finally humans can more easily have dye studies done of the brain or other tissues through the use of CAT scans or MRI's, something that is cost prohibitive or simply not available for the pet rabbit. Diagnosis in the rabbit is most often based on the rule-out of other disease such as infectious, trauma or E. cuniculi and the possibility of exposure to material contaminated by raccoon feces. Unfortunately the diagnosis is often not made until after death when the brain and other organs can be examined microscopically for the presence of B. procyonis larva. Treatment: Currently there is no effective treatment for this disease. The problem is that there is a great deal of damage already present by the time the rabbit shows signs of illness. Most antiparasitic drugs either cannot get into the tissue in high enough doses once the parasite is being walled off. Some sources suggest that using an antiparasitic drug anyway might slow down or kill the larva that are still migrating, but this has not been proven. The best thing to do is to use high levels of corticosteroids to try to suppress the inflammation that is taking place in the affected tissues. In humans this seems to help alleviate some of the signs as least temporarily. Corticoteroids will not cure the disease nor reverse all the damage, but it may minimize the trauma to the tissue. Corticosteroids have to used with caution in rabbits because they may worsen any bacterial disease present and they may cause alterations in the flora of the cecum.. An injection of a short-acting corticosteroid might be helpful initially and then continued based on the rabbits clinical response. Prevention: This is really the best option for controlling this disease. Since this disease is just as dangerous to humans and other pets as it is to rabbits then these precautions are doubly important. Here are some recommendation from Kevin Kazacos, DVM, PhD at Purdue University in W. Lafayette, Indiana. Dr. Kazacos is currently doing extensive work studying this parasite in pets and wild animals and has written a number of excellent articles on the subject. 1. Do not keep raccoons as pets. Not only are they not suitable for pets because they are wild animals, but they may pose a serious health risk. 2. Learn to recognize raccoon latrine areas and either stay away from them or clean them up if necessary. Favorite spots are at the base of trees, in the forks of trees, on fallen logs, large rocks, woodpiles, decks, in attics, garages, chimneys, barns and outbuildings. In addition raccoons like to nest in hay lofts and may contaminate hay or straw that is used for bedding or food. Purchase hay or straw from a clean source and dispose of any bales that show evidence of fecal contamination. Do not store the hay you buy in areas that raccoons have access to. Be cautious using and handling fallen timber for firewood. 3. Monitor children closely in potentially contaminated areas. Children are the most easily affected because they frequently put unwashed hands in their mouths. Do not house rabbits on the ground in areas inhabited by raccoons. It may be possible to have soil samples tested in your yard to see if the area is contaminated. Cleaning up a latrine area can be a challenge. The eggs of the Baylisascaris species are extremely resistant to environmental conditions. The eggs can survive for YEARS. They are resistant to all common disinfectants including bleach. The best way to kill the eggs is through flaming the area (including soil) or burning affected material such as straw or wood cages. Alternately, boiling water can be poured over small areas at a time. In heavily contaminated areas it may be necessary to remove and bury the soil in a deep spot elsewhere. When cleaning up any latrine area, proper protection is a must which should include a dusk mask over the nose and mouth, disposable clothing, disposable gloves and heavy rubber boots that can be cleaned with boiling water. Prevent further contamination of the area by blocking off access routes for raccoons, not feeding raccoons around the property and using repellents such as mothballs around potential access areas.
Stroke
Cause: Strokes are not nearly as common in our pets as they are in humans. A stroke is a caused by either an obstruction of the flow of blood through a blood vessel in the brain or when a blood vessel ruptures and bleeds out into the surrounding brain tissue. Both 'vascular accidents' can cause mild to severe brain tissue death. Signs: The signs are dependent on where the damage takes 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 to sudden death. The incidence of strokes increases both in animals and people with age. Rarely, an animal can have a stroke following a surgical procedure due to a blot clot becoming lodged in a blood vessel in the brain. Diagnosis: It is very difficult to diagnose a stroke in an animal without the sophisticated equipment available to humans. In humans, a diagnosis of stroke 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 suggested based on ruling out other causes of disease. Treatment: There is no treatment for a stroke. The only thing that can be done is to support the pet with fluids, assist feedings and pain medications if necessary. If the rabbit has lost the ability to control its bathroom habits, then it will have to have its 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 best and most humane course of action should be for your pet.
Bacterial Infections
Cause: There are many bacteria that can cause infections in rabbits including the well-known Pasteurella multocida.. Bacteria can enter the fluid surrounding the brain and spinal cord (cerebrospinal fluid) or small abscesses can form in the brain or spinal cord itself. Both of these conditions are rare in rabbits. Infections of the inner ear are much more common and can also lead to hind limb weakness, but is usually also associated with a pronounced head tilt. We will discuss head tilts in rabbits in another issue. Signs: The signs of infections of the central nervous system depend on the area being affected and the severity of the infection. The signs can range from depression, loss of appetite, high fever, collapse and partial or complete paralysis of the extremities. Diagnosis: Often there is an increase in the number of white blood cells seen on a complete blood cell count. Another helpful diagnostic test is looking at microscopically and culturing at a sample of cerebrospinal fluid. In the case of an inner ear infection, there may be changes seen on an x-ray of the head (but not always). Treatment: The treatment for a bacterial infection of the inner ear or central nervous system is antibiotics. The rabbit may need intensive care in the veterinary hospital including the placement of an IV catheter through which to give IV fluids and antibiotics. The prognosis for an infection of the central nervous system is guarded. The prognosis for an inner ear infection is much better, but in both cases there can be permanent nerve damage that may impair the rabbit's normal life style. As mentioned, nerve tissue takes a long time to heal and it may be weeks to months before any healing is apparent.
Neoplasia (Cancer)
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 most common cancer in rabbits (outside of the uterine cancer mentioned) is lymphoma. Lymphoma 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. Malignant cancers, such as uterine adenocarcinoma, can spread and develop new sites in the bony spinal column. Bone cancer has been noted in the rear legs of rabbits which also leads to hind limb weakness. Signs: The signs of cancer can be variable dependent on the tissues being affected and may come on gradually or may appear suddenly. Diagnosis: A diagnosis of cancer is often suspected on an x-ray and then confirmed with a biopsy of the affected tissue. Cancer in the brain or spinal tissue itself is more difficult to detect. Cancer in the bone causes dramatic changes that are easy to spot. Treatment: Chemotherapy can be attempted if it is appropriate for the particular cancer. Another option is radiation therapy if you have such facilities in your area (often they are found at a veterinary school). 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.
Systemic Diseases
Any disease of a rabbit that causes it to feel weak can cause hind limb weakness and can be confused with a true neurological disease. Bunnies that 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 interferes with normal brain and muscle function and thus leads 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. Any disease of a rabbit that causes pain on movement, may be incorrectly interpreted as hind limb weakness. For instance, pododermatitis (or sore hock...where the foot pads are raw and ulcerated) causes pain on movement, therefore the rabbit may sit hunched all day in its cage and appear to not be able to walk. Arthritic conditions of the spine (as we have mentioned in part one), hips, knees or hocks can cause an inability to move normally. Rabbits that are experiencing an intestinal shutdown either mechanically from an obstruction or physiologically from disease or inappropriate diet are often immobile due to the pain of the gas-filled intestinal tract and ultimately weakened by the disruption of the 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, is dependent on the diagnosis. A good publication that is well written and of interest to the house rabbit owner is the House Rabbit Journal. Write to House Rabbit Society, 1615 Encinal Ave., Alameda, Ca. 94501.
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