Integumentary System

Rabbits have very thin and delicate skin that is covered with fine fur comprised of both a soft undercoat and stiff guard hairs. Care must be taken when clipping fur because the skin is prone to tearing. Unlike dogs and cats, rabbits lack footpads; instead, their feet are covered with thick coarse fur that protects the plantar and palmar surfaces of the feet. Because they lack footpads, rabbits should be provided soft padded areas within their enclosures. Rabbits have nonretractable claws, making declawing an inappropriate procedure. Certain breeds of female rabbits have a dewlap, which is analogous to a second chin. Female rabbits may pluck fur from the dewlap during the breeding season to build a nest. Male and female rabbits may have three types of scent glands, including a single chin gland, paired inguinal glands, and paired anal glands. The glands are used to mark the rabbit’s territory.

Sense Organs

Rabbits’ ears represent a large amount of the animals’ surface area. Because rabbits are low in the food web, these large ears serve an important function in assisting the animal with identifying potential predators. In addition, rabbits’ ears are highly vascularized and serve an important role in thermoregulation via vasoconstriction and vasodilatation.⁵ Rabbit ears are very sensitive and delicate and should never be used for restraint.

Rabbits have a wide field of vision, which is ideal for a prey species. With the lateral positioning of their eyes and their large corneas, rabbits have an overlapping field of vision of 190 degrees.³ Although rabbits are visually acute within this region, they cannot visualize items below the horizon, including the area below their nose. Instead, rabbits use their highly sensitive vibrissae and lips as tactile structures to distinguish food items. Rabbits possess good night vision and some color vision. Rabbits have functional third eyelids that partially close with sleep or while under anesthesia.⁵ A harderian gland is found at the base of the third eyelid. If this gland prolapses, then it may present as a mass under the third eyelid. Surgical intervention is recommended to replace the gland. Tear drainage from the eyes occurs via the nasolacrimal gland. There is a single lacrimal punctum located in the craniomedial aspect of the lower eyelid. The punctum empties into a cuniculus, leading to a lacrimal sac and continuing to the base of the maxillary incisor. At this point, the duct sharply changes direction, runs along the incisor root, and emerges in the nasal cavity in the ventromedial aspect of the alar fold.² Blockage of this duct is common in captive rabbits. Affected animals may have unilateral or bilateral epiphora. Rabbits have a large retrobulbar orbital venous plexus. When an enucleation is performed, this venous plexus must be ligated to minimize hemorrhage.

Musculoskeletal System

Rabbits have a light skeleton surrounded by a very well-developed muscular system, which makes the vertebrae and long bones susceptible to fractures. To minimize the likelihood of injury, the hindlegs should always be supported when transporting the rabbit. The number of vertebrae varies between breeds, from 12 to 13 thoracic and 6 to 7 lumbar vertebrae.⁶ The epaxial and large muscles of the hindlimbs can be used for intramuscular injections.

Reproductive System

Female rabbits are classified as does, males as bucks, and neonates as kits. The onset of puberty occurs at approximately 4½ months of age; however, reproductive activity is generally dependent upon animal size, not age. In the dwarf breeds, sexual maturity occurs earlier than in larger breeds. The reproductive life of a rabbit is approximately 4 years.¹ Rabbits are induced ovulators. Their receptivity periods last approximately 14 to 16 days, followed by 1 to 2 days of nonreceptivity.² When females are ready to ovulate, they become restless, rub their chins, and assume a lordosis-like posture. Gestation lasts 31 to 32 days, and litters average 4 to 10 kits. As gestation or pseudopregnancy reaches the last 3 to 4 days, does initiate nesting behavior and line their nests with hair from the hip and dewlap.³ During this period, does consume less food, which can cause an increased risk for pregnancy toxemia. Parturition usually occurs in the early morning and lasts less than 30 minutes. Kits generally only suckle 1 or 2 times a day and are not usually seen with the doe, especially in the wild. Weaning occurs at approximately 4-6 weeks of age.

Does have two separate uterine horns and two cervices. Rabbits do not have a uterine body. The cervices open into the vagina, along with the urethra, to form one common urogenital opening. Bucks have a hairless scrotum. The inguinal rings of the buck are open, which allows the testicles to ascend and descend into and out of the abdomen. Male rabbits do not have an os penis or nipples.

Urinary System

The kidneys of rabbits are located in the retroperitoneal cavity, and their position in the body cavity is similar to that in cats. The kidneys are generally covered in fat and can be palpated on the physical examination. The urinary bladder is located in the ventral body cavity, and it is ventral to the colon. Rabbits, like rodents, have a unique system for calcium metabolism. Serum calcium is reflective of dietary calcium, and the urinary system is the primary site of calcium and magnesium excretion. Rabbits that consume a high calcium diet will often have thick and creamy urine due to the formation of calcium carbonate precipitate. On average, rabbits produce 30 to 35 ml of urine daily. Rabbit urine may be straw-colored, yellow, or red. It is not uncommon for rabbit urine to have a turbid appearance. When a rabbit presents with “red” urine, it is important to differentiate whether the urine has blood or porphyrins. Porphyrins can be produced as a result of the ingestion of various vegetables, such as beet root, cabbage, broccoli, and dandelions, or as a result of stress.²

Gastrointestinal System

Rabbits have open-rooted teeth that grow continuously throughout their lives at a rate of approximately 10 to 12 cm a year.¹ The dental formula of the rabbit is 2 × (2/1 I, 0/0 C, 3/2 P, 3/3 M). Directly caudal to the maxillary incisors is a second pair of small incisors called peg teeth, whose function is to protect the palate from injury against the sharp surfaces of the lower incisors. The buccal surface of the upper incisors’ enamel is thicker and wears more slowly than the rest of the tooth, forming a chisel-like appearance. Caudal to the incisors is a space called the diasterna.⁷ The cheek teeth are located caudal to the diasterna and are responsible for macerating and grinding food.

Rabbits have simple, glandular stomachs. Due to the positioning and well-developed nature of the cardiac sphincter, rabbits are unable to vomit.⁸ Adult rabbits have a gastric pH of 1.5 to 2.2, whereas suckling rabbits have a higher pH of 5.0 to 6.5. The higher gastric pH in neonates is necessary for bacterial colonization of the intestinal tract. This elevated pH also makes suckling rabbits more susceptible to gastrointestinal disease. Dietary absences, especially during weaning, should be gradual, and foods high in sugars and starch should be avoided. Rabbits have a large cecum that acts as an anaerobic fermentation vat. The cecum has a complex and delicate population of microbes. The most common organisms found in the rabbit cecum are the Gram-positive Bacillus spp. In the cecum, fiber is broken down and separated. Rabbits are highly susceptible to antibiotic-induced enterotoxemia, especially when there is Clostridium spiriforme contamination in the environment. The rabbit’s gastrointestinal tract is designed to eliminate fiber from the gut rapidly, in the form of hard feces, and digest the nonfiber portion of the diet, creating caecotrophs, which are reingested at a later time. Cecotrophs are covered with a thin mucus, which protects the volatile fatty acids, vitamins, and amino acids from the low pH of the stomach. Cecotrophs differ from feces in that they are soft, moist, usually stuck together, and are eaten directly from the anus.⁸ The gastrointestinal transit time in rabbits is approximately 20 hours. Rabbits offered a diet deficient in fiber usually have increased gastrointestinal transit times.

The pancreas is found within the mesentery along the lesser curvature of the stomach and extends to the right side of the abdominal cavity to the level of the duodenum. The rabbit pancreas has both exocrine and endocrine functions.

The rabbit liver has a caudate lobe with a narrow stalk, which can displace on occasion. Rabbits have a gall bladder, and the primary function of this structure is to store bile. The rabbit liver performs many of the same functions that the liver plays in the dog and cat.

Respiratory System

Rabbits are obligate nasal breathers. A rabbit that presents for open-mouth breathing generally has a guarded prognosis. The respiratory rate of the rabbit is approximately 30 to 60 breaths per minute. In a healthy animal, the nose will move up and down approximately 20 to 120 times a minute. The thoracic cavity of the rabbit is small in comparison to that of nonlagomorph or rodent mammals. Rabbit lungs have four right and two left lung lobes.³ Rabbits have an extremely narrow and long oral cavity. Because of these features, it can be difficult to visualize the glottis for intubation. Endoscopic examination provides the best visualization of the glottis for intubation. Inflammation of the upper respiratory tract increases the risk of anesthetic mortality in nonintubated animals.⁴

Cardiovascular System

Rabbits have a relatively small heart, and the average heart rate of the rabbit is 130 to 325 beats per minute.⁹ Systolic blood pressure is approximately 90 to 120 mmHg. The right atrioventricular valve has only two cusps, and the aorta rhythmically contracts.⁴ Rabbit veins are thin and susceptible to hematomas, so care must be taken with venipuncture.

Environmental Considerations

Nutrition

An average adult house rabbit should be offered ad lib grass hay, such as timothy, prairie, or oat brome; approximately 1 cup of leafy green vegetables; and, at most, ¼ cup of high-fiber (18%-22% to prevent obesity), low-protein (<18%) pellets per 2.2 kg (5 lbs) of body weight daily.^4,8 Examples of dark leafy greens include romaine lettuce, dandelion greens, Swiss chard, parsley, endive, kale, mustard greens, and carrot, beet, and turnip tops. Diets low in fiber, such as commercial, pelleted rations, may be associated with hypomotility, changes in the gastrointestinal pH and microflora, wool block from increased hair consumption, and cheek tooth overgrowth.⁷ Alfalfa hay should be avoided in adult animals, because of its high protein and calcium content, and instead, reserved for animals less than 6 months of age and for pregnant and lactating does with increased nutritional demands. When offering alfalfa hay to lactating does, slowly increase the amount over the first 5 days, as this will reduce the likelihood of milk overproduction and decrease the chance for the development of mastitis.⁴ Any diet change should be gradual.

Rabbits ingest cecotrophs formed from fermentation of nonfiber ingesta; these cecotrophs contain volatile fatty acids, vitamins, amino acids, and microorganisms. Cecotrophs are ingested straight from the anus; consuming them allows for absorption of these nutrients that would be lost otherwise. They are covered with a mucus that protects them from breakdown from stomach acids.

Chlorinated water should always be in fresh and ample supply. Rabbits are very sensitive to water deprivation and therefore should experience no restriction. Rabbits generally drink 50 to 100 ml/kg/day.² Water should be offered in a nonleaking sipper bottle or in a heavy crock that cannot be tipped over. Rabbits that drink from crocks may develop “blue fur,” which is a moist dermatitis of the dewlap that is associated with Pseudomonas infections.

Manual Restraint

Rabbit physical restraint needs to be carefully performed to avoid injury to the animal. Because rabbits have a well-developed muscular system and thin cortical bone, they are subject to vertebral and long bone fractures if restrained incorrectly. Because most skeletal injuries associated with incorrect restraint occur in the lumbar vertebrae, it is important to firmly restrain the hindlegs. Rabbits should be handled in a manner similar to cats; place one hand on under the forelimbs, and use the other hand to hold the rear legs against the body. Always place the rabbit onto a nonslip surface to ensure that it has good footing. To restrain the animal, lightly scruff the animal and support its dorsum with the same arm. The opposite arm is used to support the body and rear legs (Figure 14-1). It can be helpful to tuck the head of the rabbit into the crook of one’s elbow to decrease the rabbit’s vision, which can decrease the stress on the animal. Placing a rabbit in dorsal recumbency evokes an immobility response, which can be helpful during simple procedures. However, this response is performed by prey species under stressful or threatening conditions and may not be welcomed by all rabbits (Figure 14-2). The immobility response is characterized by a lack of spontaneous movement and a failure to respond to external stimuli. This restraint technique should only be used in those cases where chemical sedation is not desired.² A towel or blanket is usually necessary during the physical examination to cover the stainless steel exam table and to minimize slipping or kicking, which can lead to injury. In addition, a towel may be used to wrap the rabbit into a “bunny burrito” (Figure 14-3). The bunny burrito can be used to hold a rabbit for transport or to facilitate the examination of the head. Cat bags can also be used to restrain rabbits. In addition to using these techniques for examination, they can also be used to administer medication, collect blood samples, or perform nail trims.

Figure 14-1 Proper restraint while transporting a rabbit. Notice the head is tucked in the crook of the elbow and the dorsum and feet are supported.

Figure 14-2 Rabbits placed in dorsal recumbency will enter a trance-like state that may facilitate simple procedures, such as taking radiographs.

Figure 14-3 Rabbits can be wrapped firmly in a towel making a “bunny burrito.” This technique can be used to facilitate an examination, nail trim, or other noninvasive procedure.

Chemical Restraint

Chemical restraint in rabbits should be used to decrease anxiety, and to provide sedation or immobilization for surgery. (The most common drugs used for premedication, sedation, and anesthesia are described later, in Anesthesia.) Isoflurane (Abbott Laboratories, Chicago, IL) or sevoflurane (Abbott Laboratories, Chicago, IL) can be used to anesthetize rabbits; however, in high stress animals, a premedication is usually recommended.

Clinical Pathology

Venipuncture should be done with care, as rabbit vessels are delicate and prone to hematoma formation. The maximum volume of blood that should be collected at one time is 1 ml/100 g body weight.⁹ Common sites for venipuncture include the jugular, lateral saphenous, cephalic and marginal ear veins. The jugular vein is the preferred site when a large sample is needed. To collect a jugular sample, the animal needs to be properly restrained. For restraint, a rabbit can be placed into a towel or a cat bag, and the neck gently extended in a manner similar to a cat; however, care should be taken not to extend the head too far. In some female rabbits, a large dewlap can reduce access to the jugular vein. Marginal ear veins can be used to collect blood samples with a 25- or 26-gauge needle. Generally, this site can only be used to collect small blood samples. This vein can also be used to place a catheter; however, catheterization can lead to vascular necrosis, thrombosis, and sloughing of the ear and should be avoided in breeds with small ears (e.g., dwarf breeds). The lateral saphenous vein is suitable for small- to moderate-sized blood samples (Figure 14-6). Placing alcohol over the venipuncture site or clipping the fur in that area can facilitate visualization of the vein. The cephalic vein can also be used to collect samples; however, this site is often reserved for intravenous catheter placement.

Figure 14-6 Shaving the lateral hindlimb will facilitate visualization of, and access to, the lateral saphenous vein.

Hematology/Chemistry Panels

CBCs and serum chemistry panels should be performed in rabbits presenting for any disease process and as part of an annual exam. Rabbits have some unique hematologic differences in their CBC compared to other mammals. Healthy rabbits are primarily lymphocytic. Both small and large lymphocytes can be found in circulation. Rabbit lymphocytes are similar in appearance to this cell type in other vertebrates and are characterized by a deep blue cytoplasm, acentric nucleus, and high nuclear-to-cytoplasmic ratio. The acute inflammatory cell in rabbits is the heterophil. Although the function is similar to the neutrophil of other mammals, the staining characteristic of this cell type is different. Monocytes are the largest circulating white blood cell in rabbits and are characterized by diffuse nuclear chromatin, blue cytoplasm, and large, dark red granules in cytoplasm.^9,11 Eosinophils have large granules and a bilobed or horseshoe-shaped nucleus. Low-grade eosinophilia can be seen with chronic parasitism. Basophils are relatively common in rabbits and can represent up to 30% of the differential in healthy animals. Infections rarely cause elevated white blood cell counts (>15,000 cells/ml) in rabbits; however, several changes may be associated with an acute infection, including a low total number of white blood cells (<5000 cells/ml) with a normal differential or normal cell counts with a shift to heterophilia, thrombocytopenia, and nucleated red blood cells. Other reasons nucleated red blood cells may be found are endothelial changes and regenerative responses.

Rabbits, like rodents, have control over calcium excretion at the level of the kidney. Elevations in serum calcium can be attributed to an increase in dietary intake of the mineral or to renal disease; a reduction in serum calcium may be indicative of hypoalbuminemia, diarrhea, chronic renal failure, or hyperparathyroidism. Phosphorous can also increase with renal disease, but reduced levels can be seen with calcium excretion in the urine.

As with other mammals, creatinine levels can become elevated when reduced blood flow to the kidney occurs accompanied by a 50% to 70% loss of renal function. Blood urea nitrogen may also rise due to renal disease when 50% to 70% of kidney function is lost. There are a number of potential causes of renal failure in rabbits, including neoplasia, glomerular nephritis, and pyelonephritis. Elevations in blood urea nitrogen and creatinine can also occur with postrenal diseases (e.g., urethral calculi) and prerenal diseases (e.g., dehydration).

There are no liver-specific enzymes in rabbits. In many mammals, alanine aminotransferase is liver specific; however, in rabbits, this enzyme is found in both the liver and cardiac muscles. Aspartate aminotransferase is found in a number of tissues, including muscle (cardiac, skeletal, smooth), liver, kidneys, and pancreas. Elevations of both enzymes, however, should be considered suspicious and other testing done to rule out liver disease (e.g., liver biopsy). (See Table 14-1 for rabbit hematologic and serum chemistry reference ranges.)

TABLE 14-1 Reference Hematologic and Serum Chemistry Values for Rabbits

The electrolytes reference ranges for rabbits are similar to those described for other mammalian vertebrates (see Table 14-1). Elevations in sodium and chloride can occur with dehydration or excess salts in the diet, whereas losses are generally associated with diarrhea or low dietary salt. Potassium levels may be low in animals with diets low in potassium or in animals that are starved. Total protein levels in rabbits can be higher compared to those levels found in other vertebrates.

Urinalysis

A urinalysis can provide a significant amount of information regarding a rabbit’s health. Either a free-catch or cystocentesis urine sample can be used, but the cystocentesis sample is preferred. To perform a cystocentesis in a rabbit, a 22- to 25-gauge needle fastened to a 6-ml syringe is needed. The rabbit should be placed in dorsal recumbency. The bladder can be difficult to palpate; however, with care, it can be found cranial to the pelvis. The cystocentesis site should be disinfected with 70% isopropyl alcohol. The rabbit bladder should be stabilized between the index finger and the thumb, and the needle inserted along the ventral midline into the bladder. The consistency of the urine should be noted.

Urinary catheterization can be performed with a well-lubricated 9-French catheter inserted into the urethra.¹¹ Rabbit urine is generally straw-colored and clear to cloudy. If the urine has a red appearance, then it is important to rule out blood in the urine from porphyrins. To differentiate hematuria from porphyrin pigmentation, use a urine dipstick or a woods lamp, as porphyrins will fluoresce. If a urinary tract infection is suspected, obtain a cystocentesis and submit a culture and sensitivity in addition to performing a complete urinalysis. Cloudy urine in rabbits is usually due to calcium excretion and the presence of crystals. The presence of crystals in the urine can make it difficult to identify bacteria on a cytologic test, and a culture should be performed if a bacterial cystitis is suspected. (See Box 14-2 for normal urinalysis values.)

Fine needle aspirates can be done to ascertain the histologic response of a mass. Although abscesses are a common finding in dermal and subcutaneous masses, neoplasia, granulomas (e.g., fungal), and hematomas can also occur. Rabbit abscesses are generally inspissated, so it is difficult to obtain much of a sample from a fine needle aspirate. The procedure for fine needle aspiration in a rabbit is similar to the technique described for domestic mammals. Using a local anesthetic can minimize the pain associated with the procedure. Applying topical EMLA cream (AstraZeneca LP, Wilmington, DE) over the fine needle aspirate site 20 to 30 minutes before performing the procedure can minimize the discomfort associated with the procedure.

Bone marrow aspirates should be performed when blood cell production problems are suspected. The proximal femur is the preferred site for sample collection. This procedure should be done with general anesthesia. A standard sterile preparation should be done to minimize the likelihood of introducing opportunistic skin pathogens. A spinal needle with a stylet should be used to perform the procedure. The needle should be inserted in the trochanteric ridge.

Diagnostic Imaging

Radiography is a useful diagnostic test in rabbit medicine. It is important to always take at least two radiographs (e.g., lateral and dorsoventral/ventrodorsal). Many times radiographs of the abdomen or thorax can be taken with little or no sedation if the handlers are patient and careful. If more restraint is necessary, isoflurane or midazolam can be used to sedate or immobilize the patient. Skull radiographs are required to evaluate the roots of molars and incisors and should be taken in cases of suspected or known malocclusions. The most useful radiographic views for examining the teeth are rostrocaudal, dorsoventral, and lateral (Figure 14-7). In cases of ocular discharge, contrast media can be injected into the lacrimal duct to determine if any of the molar roots are impinging on the duct (Figure 14-8). Chronic cases of otitis or neurologic disease warrant evaluation of the tympanic bullae for radiographic changes. In cases of facial abscess, radiology can be used as a prognostic indicator; periosteal bone reaction decreases the prognosis for full recovery.

Figure 14-7 Normal lateral skull radiograph of a domestic rabbit.

Figure 14-8 Contrast media can be instilled into the nasolacrimal duct to determine if the incisors are impinging on the duct.

Abdominal radiographs can be used to assess the gastrointestinal, reproductive, and excretory systems. Survey radio graphs can be useful for diagnosing ileus or gastric foreign bodies. Rabbits with severe generalized ileus carry a grave prognosis. Rabbits with trichobezoars are frequently anorectic. Therefore, the presence of a soft tissue mass in the stomach of an anorectic rabbit is highly suggestive of the presence of a gastric foreign body (e.g., trichobezoar). In cases where a gastrointestinal foreign body is suspected but not conclusive from survey radiographs, the veterinarian should consider doing a contrast study. Uterine adenocarcinoma should be considered in a differential list for any intact doe with a suspicious soft tissue mass in the caudoventral abdomen. Renal, urethral, and cystic calculi can generally be diagnosed from survey radiographs, although contrast studies are also needed in some cases.

Thoracic radiography is an important diagnostic test for ruling out respiratory and cardiac disease. The thoracic field of a rabbit is small in comparison with that of other mammalian vertebrates (Figure 14-9). However, radiograph interpretation is similar. Pneumonia, metastatic neoplasia, and trauma are common disease problems that can be diagnosed radiographically.

Figure 14-9 Normal thoracic radiograph. Note the small size of the thorax.

In addition to radiography, the other commonly used diagnostic imaging techniques can also be useful for assessing the rabbit patient. Ultrasound can provide excellent images of the abdomen and thorax and has been used to diagnose abdominal pathology, uterine disease, foreign bodies, excretory calculi, and cardiac disease. Success with ultrasound is based on the sonographer having a good knowledge of anatomy, so that he or she can interpret an image based on the position of the probe. A 7.5- to 10-mHz transducer is recommended for rabbit ultrasonography. Clipping the fur of the rabbit in the area of interest can also help improve the image by providing the contact between the skin and the probe; however, caution must be used when clipping the fur, as the skin tears easily. Echocardiography is an appropriate diagnostic aid in cases of suspected heart disease or in patients with audible murmurs. Echocardiographs should be conducted using a high-frequency transducer (7.5-12 MHz) and high frame rate ultrasound machine.⁴ Magnetic resonance imaging and computed tomography (CT) can prove invaluable in diagnosing certain conditions, including diseases associated with the sinuses, inner ear, cranium, and teeth. Although these tests are becoming more available, they still remain cost prohibitive for some clients.

Microbiology

Bacterial and fungal cultures are routinely collected to assist in the diagnosis of specific pathogens. Interpretation of the results, however, can sometimes require more art than science. It is important for veterinarians to recognize that the results they receive from their laboratories are based on what happens at the level of the culture plate. For example, although Pasteurella multocida is often considered a primary differential in many cases based on the animal’s presentation, the culture results may suggest otherwise. P. multocida is a fastidious organism and may be outcompeted on a plate by other organisms (e.g., Staphylococcus spp.). Therefore, the interpretation of the results should be reviewed cautiously.

Rabbits can become bacteremic and develop an infection in practically any tissue. The most common sites of infection, however, are the urinary bladder, respiratory system, and integument. Urine cultures obtained from cystocentesis are preferred to those collected via free-catch. Rabbit urine should have a basic pH. If the urine pH becomes acidic, it will promote the growth of potential opportunistic pathogens. Most pathogens of the urinary tract are Gram-negative bacteria. Female rabbits are more susceptible because of their stouter urethras. In addition to urine cultures, deep nasal cultures for chronic respiratory disease and cultures of abscesses are considered routine. Deep nasal cultures usually require sedation, as the microculturette is advanced into the nasal passage up to the level of the medial canthus of the eye. When culturing an abscess, the best results are often obtained from sampling the abscess wall.¹¹ Samples collected from the nasal sinuses and abscesses often have a significant number of inflammatory cells associated with them. These cells can affect the results of a culture by reducing the number of organisms to the point where analytical sensitivity of culture cannot detect the bacteria. In some cases, serial samples may be needed to determine if an organism is a trace pathogen. Culturing microorganisms from rabbits is otherwise routine. If anaerobes are suspected, then the veterinarian should contact the laboratory to obtain the appropriate media for collection and transport.

Parasitology

Although rabbits are captive bred, and the expectation is that parasites would be absent or low in these animals, parasites remain a problem because few preventive health programs are instituted at the breeding population level. Endoparasites can be diagnosed using routine direct saline smears or fecal flotations. Direct saline smears are preferred for identifying protozoa, whereas a fecal flotation is preferred for finding nematodes, trematodes, and cestodes. Annual parasitological examinations include both techniques. Because parasites can be shed transiently, serial samples should be performed. Pooling fecal samples produced over the course of a week may reduce the likelihood of misclassifying a rabbit’s parasitic status. For systemic parasitologic disease, serologic testing or histopathology is required. E. cuniculi, a microsporidian, is generally diagnosed antemortem via serology or postmortem via histopathology. E. cuniculi is shed in the urine and may also be diagnosed from direct visualization in a urine sample, but this is not analytically sensitive. Eimeria steidae, a hepatic coccidian, can be diagnosed antemortem via a fecal direct smear or postmortem via histopathology.

Ectoparasites are also common in captive rabbits. If ectoparasites are suspected, a routine dermatologic examination should be performed, including a skin scrape and mineral oil preparation of the fur. Microscopic examination of these samples can provide confirmation of the presence of these parasites. Multiple samples should be collected to prevent misclassification as negative, and samples should be collected along the edge of the lesion. A flea comb can be used to confirm the presence of adult fleas or flea dirt.

Miscellaneous Diagnostics

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