Clinical history

A 6-year-old neutered female rabbit (Oryctolagus cuniculi) was presented with a large oral mass. While this was not causing irritation, it had begun to interfere with the eating. The owner had first noticed the mass 3 weeks previously but had not taken it for examination as the rabbit appeared well.

Physical examination

The rabbit appeared well and in good body condition. The mass in the left cheek was easily palpable and could be visualized on oral examination with an auriscope. The surface appeared smooth with no ulceration (Fig. 1.1). There was no pain associated with the mass. Dental roots could not be palpated. Oral examination (as far as it allowed) detected no evidence of dental disease. The mass did not appear excoriated or ulcerated. There were no other masses detectable in the abdomen or on the skin.

Fig. 1.1 (a) Photograph showing the oral mass present in the oral cavity of the rabbit; (b) close-up photograph showing the oral mass in the oral cavity of the rabbit.

1. What are your differentials for this mass?

Differential diagnoses

2. How would you distinguish between these differentials?

Fig. 1.2 (a) Ventrodorsal survey radiograph of the head of the rabbit; (b) latero-lateral radiograph of the head of the rabbit.

Fig. 1.3 Latero-lateral survey radiograph of the thoracic cavity of the rabbit.

3. What biopsy technique would you recommend?

Laboratory diagnosis

Histological diagnosis

Comments

The submitted mass contains an odontogenic epithelium that exhibits the characteristic palisading, basilar clearing, apical nuclear polarity and a population of loose stellate cells within the middle of these trabeculae. There are, in addition, in this mass, multiple areas of squamous metaplasia and keratinization as well as multifocal mineralization. The epithelial component appears to be the predominant component of this mass and these features are most consistent of a keratinizing ameloblastoma. There is little information in the literature as to odontogenic tumour in rabbit but, in other species, ameloblastoma is expected to behave in a locally infiltrative manner but metastasis is not expected. Excision would be expected to be curative for this mass.

Therapy

On the basis of these results, the mass was removed during a second anaesthetic (sevoflurane induction: isoflurane maintenance).

The mass was removed using radiosurgery (Fig. 1.4). It was well encapsulated – histopathology confirmed it had been completely removed. The wound was sutured using 4/0 Vicryl (Ethicon) and covered with Orabase gel.

Fig. 1.4 Oral mass after removal using radiosurgery.

4. What postoperative care would you recommend?

Postoperative medical management

Clinical history

A 6-month-old female rabbit (Oryctolagus cuniculi) was presented with crusting around the nose and eyes and an ocular discharge. The rabbit had been purchased from a shelter a few weeks previously and there was no history of vaccination.

Physical examination

The rabbit appeared well on examination. There was hair loss and crusting around the eyes with evidence of a serous ocular discharge though there were no signs of conjunctivitis (Fig. 1.5). There were many scabs around the nose with associated purulent discharge (Fig. 1.6). These appeared partially to occlude the nares, resulting in an increased respiratory effort, and nose. Other than referred noise there were no abnormalities on thoracic auscultation. There was also crusting around the vent (Fig. 1.7). There were no other signs on examination.

Fig. 1.5 Close-up photograph of the rabbit showing hair loss and crusting around the eye with evidence of serous discharge.

Fig. 1.6 Close-up view of the nose showing scabbing with associated purulent discharge.

Fig. 1.7 Close-up image showing some crusting around the perimeter of the vent.

1. What are your differentials?

Differential diagnoses

2. How would you investigate?

Diagnostic plan

Given cost constraints and the unlikelihood of vent lesions being linked to respiratory disease the owner decided against skull radiography.

Initial therapy

Following the biopsy, the rabbit was placed on enrofloxacin at 30 mg/kg daily by mouth pending the results.

By the time results returned (7 days) the lesions had worsened.

4. Why do you feel this was the case?

Presumptive diagnosis

The most likely diagnosis from clinical signs and history is treponemiasis. Even though special stains were used, it is still not unusual for the organisms to be undetected on biopsy or cytology, especially if there is a concurrent bacterial pyoderma.

5. What other diagnostics may be used?

Additional diagnostic laboratory testing

Trial therapy

Trial therapy using amoxicillin at 50 mg/kg weekly SC on three occasions was started. Prior to therapy, the rabbit was placed on a grass and hay only diet (to preserve gut pH) and reduce the chances of alteration of gut flora when using a penicillin. A week later, the lesions had 75% resolved and were fully resolved by the final injection. This generally gives a presumptive diagnosis of treponemiasis.

There were no other rabbits in the household (it is generally advised to treat all in-contacts) but the owner was instructed to alert the rescue shelter. Benzyl or benzathine penicillin preparations are more normally used in the treatment of treponemiasis. However, this drug is currently unavailable other than in preparations containing antibiotics toxic to rabbits. However, long-acting amoxicillin preparations appear equally effective. This case illustrates that diagnostic testing is susceptible to error and that clinical medicine still has a role for acumen and trial therapies.

Clinical history

A 7-year-old female lop rabbit weighing 2.5 kg was presented with the following clinical signs and symptoms of one week’s duration:

Clinical examination

On presentation, the rabbit was a good weight and bright and alert. Abnormalities included white exudate in the right ear canal, and thickening of the base of the ear. The left ear canal was stenotic and could not be visualized beyond the horizontal portion. There was scant dried ocular discharge associated with the right eye. The rest of the examination was unremarkable. A blood sample was collected for haematology, which was unremarkable, and chemistry analysis, which is presented in Table 1.1. The rabbit was then sedated for survey radiographs of the skull, and collection of a sample from the right ear canal for culture and sensitivity.

Table 1.1 Blood chemistry results of the rabbit

Radiology

1. What is your interpretation of the radiographs in Fig. 1.8a–d?

Fig. 1.8 Radiographs of the skulls of two rabbits. (a,b) Ventrodorsal and latero-lateral radiographs of the skull of the affected rabbit; (c,d) close-ups of normal osseous bullae in an unaffected rabbit.

Radiography interpretation

2. What is your interpretation of the blood chemistry and plasma protein electrophoresis values of the rabbit (Tables 1.1 and 1.2)?

Table 1.2 Plasma protein electrophoresis of the rabbit

Results

Please evaluate the clinical history, Fig. 1.8a–d, the results of the physical examination and clinical diagnosis laboratory tests.

3. List your differential diagnoses.

4. List your therapeutic strategy, and suggestions for additional diagnostic testing, if indicated.

Differential diagnoses

Therapy (Table 1.3)

Table 1.3 Therapy

Additional diagnostic testing

Culture and sensitivity of the ear canal revealed no growth of organisms. The owner elected to take the rabbit home on long-term antibiotic therapy without further evaluation or treatment of the ear canal. Two months later, the rabbit developed a mild left head tilt and horizontal nystagmus. The owner agreed to additional diagnostic testing at that time. The rabbit was anaesthetized for otoscopy of both ears and computed tomography of the skull. Otoscopy revealed bilateral otitis externa with an apparent intact tympanic membrane on the right side; the left could not be visualized due to marked stenosis of the horizontal ear canal.

5. What is your interpretation of the computed tomography image presented in Fig. 1.9?

Fig. 1.9 Computed tomography. Axial view of the tympanic bullae, bone and soft tissue window.

Complete evaluation of the scan by a radiologist confirmed bilateral otitis media and externa; there were no other abnormalities noted.

6. What are your recommendations for further therapy for this patient?

The rabbit was referred to a university-based veterinary surgeon with significant experience with this surgery in the rabbit. The surgery site was implanted with gentamicin and cefazolin impregnated beads at the time of surgery. Post-surgical care included meloxicam (0.2 mg/kg once daily PRN, enrofloxacin 10 mg/kg PO once daily, cisapride 0.5 mg/kg BID and support feeding.

Final diagnosis

Discussion

Otitis is a common disease in older rabbits, especially in lop varieties due to the abnormal anatomy of the external ear canal. Flexion and stenosis of the external ear canal can predispose to infection, which can progress to otitis media. Otitis media is also thought to originate from single or multiple foci of infection of the skull as a result of dental disease and/or sinusitis. Symptoms seldom develop until late in the course of the disease, and can include tilting of the head to one side, head shaking, scratching of the ears, inappetence, and depression. In cases where infection produces inflammation of the associated cranial nerves, a variety of neurological abnormalities can be seen: peripheral vestibular diseases, nystagmus, and facial nerve paralysis and Horner’s syndrome. Antibiotics do not penetrate well into the infected osseous bullae due to vascular compromise, therefore, medical therapy is often only partially effective to completely unrewarding. In cases where abnormalities of the bullae are confirmed, osteotomy is recommended. It should be noted that computed tomography is a superior diagnostic imaging for evaluation of the bullae when compared to radiography.

Clinical history

A 4-year-old male rabbit weighing 5.71 kg was presented with the following clinical signs and symptoms:

The rabbit had been cared for by a rescue organization for 3 years, and had no previous medical history. A normal wellness exam was performed 6 months prior and was unremarkable. Diet was grass-based commercial pellets, grass hay and limited greens.

Clinical examination

On presentation, the rabbit was a good weight, but clinically dehydrated based on skin turgor. The abdomen was painful upon palpation. Stomach was fluid-filled and enlarged, and there was gas palpable in the caudal abdomen. The rabbit was depressed, but responsive to handling. The rabbit was administered midazolam at 0.25 mg/kg and hydromorphone at 0.1 mg/kg for sedation and analgesia. Radiographs were obtained using manual restraint only.

Radiology

1. What is your interpretation of the radiographs in Fig. 1.10a, b? Note that patient size precluded inclusion of the entire abdomen in a single view.

Fig. 1.10 (a) Lateral radiograph of portions of the abdomen of the rabbit; (b) ventrodorsal radiograph of portions of the abdomen of the rabbit.

Radiology interpretation

Clinical diagnosis laboratory examination

Blood was obtained from the lateral saphenous vein, and an in-house biochemistry was obtained, along with a blood film and haematocrit. Evaluation of the blood film, and the haematocrit were unremarkable (Table 1.4).

Table 1.4 Blood chemistry values of the rabbit

2. What is your interpretation of the findings of the results of blood analysis?

Differential diagnoses

Therapy (Table 1.5)

Table 1.5 Therapy

Additional diagnostics

After 12 hours of therapy, condition had not improved. Repeat radiographs were obtained after re-administration of midazolam for sedation.

5. What is your interpretation of the radiographs in Fig. 1.11a, b?

Fig. 1.11 (a) Lateral radiograph of portions of the abdomen of the rabbit, 12 hours post-presentation; (b) ventrodorsal radiograph of portions of the abdomen of the rabbit, 12 hours post-presentation.

Radiology interpretation

At this point abdominal ultrasound and exploratory surgery were declined and euthanasia elected.

Post-mortem findings

The rabbit was euthanased and necropsy performed in-house (Fig. 1.12). The stomach was enlarged, and fluid-filled with mild serosal haemorrhages. The lower GI was partially filled with gas. There was no evidence of obstruction.

Fig. 1.12 Post-mortem examination of the rabbit.

6. What additional lesions can you observe in the post-mortem image (see Fig. 1.12)?

Summary of post-mortem examination findings

Final diagnosis

Discussion

Gastrointestinal stasis is a common finding in ill rabbits. While in occasional cases stasis is a result of primary gastrointestinal disease, this syndrome can accompany many underlying conditions, including physiological and psychological stress, and worsens with anorexia and dehydration.

In this case, clinical condition and radiographic appearance of the gastrointestinal tract worsened despite therapy. This is often the most important indicator for surgical intervention. Liver torsion is common in rabbits, and involves the right caudate lobe of the liver, which is small with a narrow attachment to the hilar region. All documented cases of liver torsion involve this lobe. It is uncertain what predisposes liver to torsion, however, many affected rabbits are larger breeds, as in this case.

Diagnosis can be challenging and rabbits can present with variable, sometimes vague symptoms. However, many present with evidence of abdominal distress and show marked elevation in ALP. Disease is acute, and there is often no specific radiographic evidence of torsion. Ultrasound may be useful. Confirmation is at exploratory surgery. There are several reports of successful surgical management of this condition when it is identified early in the course of the disease. Treatment consists of surgical removal of the affected liver lobe, and aggressive supportive care.

Clinical history

A 5-month-old rabbit weighing 1.8 kg was presented with the following clinical signs and symptoms:

The rabbit was acquired one month previously from a pet store, and seemed otherwise healthy. Diet was commercial pellets, hay and occasional greens.

Physical examination

On presentation, the rabbit was slightly thin, but bright and alert. The mandibular incisors were elongated and deviated rostrally, protruding from the mouth. The maxillary incisors were elongated and curving caudodorsally. A cursory examination of the oral cavity with an otoscope in the conscious patient was attempted, and clinical information was minimal, but unremarkable. There were no other significant clinical findings. Blood was obtained for pre-anaesthetic work up (haematocrit and biochemistry panel) and was unremarkable. The rabbit was anaesthetized for complete oral examination and radiography of the skull.

Clinical diagnosis examination

Radiology

1. What is your interpretation of the radiograph in Fig. 1.13a, b?

Fig. 1.13 (a) Photograph of the rabbit showing the overgrown incisors and (b) lateral radiograph of the skull of the rabbit.

Oral examination and endoscopy

2. What is your interpretation of both the radiographs and the findings from endoscopy in Fig. 1.14a–c?

Fig. 1.14 Multiple endoscopic images of the oral cavity of the rabbit.

Results

3. List your differential diagnoses.

4. List your therapeutic strategy.

Differential diagnoses

Therapy (Table 1.6)

Table 1.6 Therapy

Discussion

Congenital jaw malformation is well described in rabbits and may represent a mandibular prognathism or maxillary brachygnathism. This malformation results in an abnormal occlusal plane and the inability of the incisors to wear normally upon each other, resulting in elongation, which can be extreme. Patterns of elongation vary but, in the rabbit, mandibular incisors typically elongate rostrally while maxillary incisors begin to curve caudally as they encounter the elongated mandibular incisors. Elongation may or may not result in perforation of soft tissues. Rabbits readily adapt to malocclusion and will continue to eat until the disease is severe. The best option for treatment of this condition is extraction of the incisors (Fig. 1.15). The technique is well described, and generally tolerated well. Prehension of food is performed with the lips and tongue; therefore rabbits are able to eat a normal diet, including hay. The loss of incisors, however, results in inability to cut larger food items into small pieces for prehension, for example whole carrots and large greens. These rabbits are also unable to cut naturally growing greens from the ground when foraging outdoors. These disabilities are minor and do not result in impacted quality of life.

Fig. 1.15 Radiographs of the skull of the rabbit post-extraction of the incisors.

Stay updated, free articles. Join our Telegram channel

Join