By Dr. Laurie Hess, DVM, Diplomate ABVP (Avian Practice)
Rabbits are perhaps the most popular small mammals kept as pets. They make great companions and can live a dozen or more years when they are cared for properly. However, they do commonly develop a few illnesses that all rabbit owners should be aware of so they can try to prevent them from occurring, or at least recognize the signs they cause so they can seek care for their rabbits if these signs occur. The five most common illnesses in rabbits are:
Gastrointestinal (GI) Stasis
The term “hairball” has been used for decades to describe a syndrome in rabbits in which they stop eating, stop passing stool, and become bloated with GI tract gas, fecal material, and dry mats of hair. The assumption was that the “hairball” was the cause of the slowing down or complete cessation of food movement through the GI tract. However, this is not true. The hairball actually is a result of, rather than the cause of, the problem.
Rabbits normally have some hair in their GI tracts from grooming. With GI stasis, the problem is not an accumulation of hair in the stomach but instead decreased movement of food through the GI tract from a combination of decreased food intake, dehydration, and changes in the population of GI bacteria that normally ferment the food in a healthy rabbit’s GI tract. As a result, food and dehydrated mats of hair form an impaction, typically in the stomach. The appropriate term for this condition is GI stasis, and it can be a life-threatening problem in rabbits if they are not treated as soon as signs occur.
GI stasis commonly develops when rabbits stop eating for a variety of reasons, including dental problems, respiratory tract infections, or even stress. Regardless of the cause for their not eating, rabbits showing signs of GI stasis should be examined by a veterinarian immediately and treated with subcutaneous fluids (or intravenous fluids, if they are very dehydrated), GI motility-enhancing medications, anti-gas drugs, and syringe feeding. Veterinarians should also diagnose and treat the primary cause of the rabbit’s decreased appetite.
When treated early and aggressively, rabbits can make a full recovery even from severe GI stasis.
Teeth problems are also very common in rabbits and are often linked to improper diet.
Rabbits’ teeth (both front incisors and back molars) are open-rooted and grow continuously, up to 4-5 inches a year. Rabbits’ teeth will often overgrow when rabbits are eating excess amounts of soft, crumbly pellets and are not grinding their teeth down by chewing on enough coarse hay, as they would in the wild.
Once overgrown, molars may become abscessed at the roots or form sharp spurs/points on their surfaces from abnormal wear. The sharp edges can cut into the tongue, gums, and cheeks. When upper and lower teeth do not meet properly during chewing to wear down sufficiently, the rabbit is said to suffer from dental malocclusion. Front teeth may overgrow to the point that they protrude out of the mouth, grow at an angle to each other, curl back into the mouth, curl sideways, or take on other problematic positions.
Rabbits with dental disease will often drool, stop eating, stop passing stool, and develop secondary GI stasis. Rabbits with these signs should be examined right away by a veterinarian who can trim the teeth to try to re-establish normal occlusion of upper and lower teeth, as well as treat signs of GI stasis, if they are present. Tooth root abscesses may require teeth extraction under anesthesia, plus administration of antibiotics and pain relievers.
Once they are eating again, rabbits with dental problems must be fed hay to try to prevent tooth re-overgrowth. Unfortunately, many rabbits with dental problems suffer from them long-term and require repeated veterinary treatment.
Statistics show that as many as 70 percent of un-spayed female rabbits over 3-4 years of age develop uterine cancer. For this reason, all female rabbits should be spayed (have their uterus and ovaries removed) as soon as possible after 5-6 months of age.
Un-spayed female rabbits often initially develop benign changes in their uterine endometrium (lining) that progress to malignant cancer over time. After several months, uterine cancer can spread or metastasize from the uterus to other parts of the body, especially the lungs. Once the cancer has spread, the condition is typically fatal. However, before it spreads, uterine cancer is completely curable if the rabbit is spayed. Rabbits with uterine cancer may at first show no signs other than a decreased appetite. Some may develop GI stasis. Over time, they may have bloody urine. They may lose weight and appear to have swollen bellies from a distended uterus. Rabbits with any of these signs should be examined by a veterinarian, who can often feel the rabbit’s enlarged uterus through her abdomen.
A rabbit with a palpably enlarged uterus should have an x-ray of its abdomen and chest to ensure that no tumors are visible in the chest and to confirm that the uterus alone is being affected. Sometimes an ultrasound of the belly is required to confirm that the uterus is enlarged. If it is, and the chest looks clear, the rabbit should be spayed as soon as possible.
Tilting the head to one side — referred to as torticollis — is a common sign in rabbits that can have different causes. The two most common causes of torticollis in rabbits are inner ear infection with bacteria and brain infection with a parasite called Encephalitozoon cuniculi (or E. cuniculi).
Inner ear infection with bacteria is especially common in lop-eared rabbits whose ears point down and may, as a result, trap moisture and grow bacteria more easily in the ear canals. These rabbits may be eating and active and simply have a head tilt toward the infected ear, or they may be lethargic, not eating, have involuntary eye movements back and forth, and have vertigo to the point that they are rolling over and over on their sides in the direction of the head tilt. Pus may or may not be visible in the ear canal when a veterinarian looks into it with a lighted scope.
X-rays of the head showing pus inside the inner ear, which is actually inside the skull, as well as a moth-eaten appearance to the skull bones, may be necessary for a veterinarian to confirm that there is inner ear disease. Treatment involves long-term administration of antibiotics and anti-inflammatory drugs, as well as supportive care, such as syringe feeding.
E. cuniculi is a microscopic parasite that infects the brain and spinal cord (central nervous system, or CNS), causing various abnormal neurologic signs including head tilt, circling or rolling to one side, seizures, repeated stretching of the limbs, and abnormal eye movements. Some rabbits carry this parasite in their CNS without showing any signs, and they spread it to other rabbits through their urine.
E. cuniculi infection is impossible for a veterinarian to distinguish from inner ear infection without x-rays and blood tests. Rabbits diagnosed with E. cuniculi are treated long-term with anti-parasitic and anti-inflammatory medications and supportive care, such as assisted feeding, as needed. Head tilt often resolves in these rabbits, but for some, it persists, and they learn to adapt to the condition, despite the tilt.
Respiratory Tract Infections
Rabbits are obligatory nasal breathers, meaning they must breathe through their noses and cannot breathe well through their mouths. They commonly get respiratory tract infections that can affect both their upper airways (nose and trachea) and lower airways (lungs).
Rabbits with infections confined to their upper airways often are referred to as having “snuffles.” Rabbits with mucus and discharge blocking their nasal passages may sneeze repeatedly and have trouble breathing. “Pneumonia” is reserved for those that have an infection affecting the lower airways as well as the upper. Those with pneumonia may also have trouble breathing, and may wheeze and sneeze.
Rabbits with respiratory tract infections may have decreased appetites, eye discharge, decreased stool production, and weight loss. They may develop GI stasis secondary to respiratory tract infection.
Respiratory tract infections in rabbits are most commonly caused by bacteria — especially bacteria called Pasteurella. Pasteurella bacteria are often carried by rodents, such as guinea pigs; thus, rodents and rabbits should never be housed together.
Other types of bacteria, beside Pasteurella, as well as certain viruses, and occasionally fungus, can cause respiratory tract infections in rabbits, too. Rabbits with respiratory tract infections — especially those that are having trouble breathing — should be checked by a veterinarian as soon as possible. X-rays are often necessary to assess the rabbit’s lungs. Severely affected rabbits may need to be given oxygen, antibiotics, and anti-inflammatory drugs, as well as fluids subcutaneously or intravenously, and syringe feeding. Rabbits with blocked nasal passages may need their nostrils cleared so that they can breathe.
Left untreated, rabbits with respiratory infections can die. With long-term medical treatment and supportive care, however, even rabbits with pneumonia can make a full recovery.
In general, rabbits can thrive as pets when they are fed and cared for properly. It is critical that rabbit owners be familiar with common illnesses in their pets so that they can recognize and treat them as soon as they occur.