Clinical presentation, treatment, and outcome of dacryocystitis in rabbits: a retrospective study of 28 cases (2003-2007)

Computed Tomographic Findings Secondary to Dental Pathologies: Comparison between Rabbits and Guinea Pigs

(1) Background: dental pathologies are the most frequent reason for requesting a CT scan of the head in rabbits and guinea pigs. The study aimed to review head CT exams of both species to identify and characterize lesions secondary to dental disease. (2) Methods: head CT studies of 48 rabbits and 52 guinea pigs with dental pathologies were reviewed. (3) Results: dental abnormalities of mandibular teeth were the most represented, both in rabbits (81.2%) and guinea pigs (98%). The aggressive bone lesion associated with teeth was the more frequently observed bone lesion in rabbits' mandible and maxilla; in guinea pigs, the more frequent bone lesions were bulging around the roots of the teeth with focal lysis in the maxilla, and without focal lysis in the mandible. In the maxilla, the increased attenuation of nasal cavities (rhinitis) was the most frequently observed abnormality both in rabbits (60%) and guinea pigs (83.3%); the exophthalmos was more represented in rabbits (53.3%). In the mandible, the cavernous space-occupying lesion was more represented both in rabbits (92.3%) and guinea pigs (73.3%). (4) Conclusions: lesions secondary to dental pathologies were often observed both in rabbits and guinea pigs; CT examination has proven to be valuable in detecting secondary alterations in both species.

Stenting of a partially obstructed nasolacrimal duct using a steerable angle-tipped hydrophilic guidewire in a cat

OBJECTIVE

This case report describes the successful correction of partial obstruction of the NL duct in a cat by means of a modified retrograde NL duct cannulation using a steerable angle-tipped hydrophilic guidewire (AH guidewire) following a paranasal incision.

ANIMAL STUDIED

A 2-year-old neutered male American domestic shorthair cat was referred to the Purdue University Veterinary Hospital (PUVH) for chronic epiphora suspected secondary to nasolacrimal (NL) system obstruction.

PROCEDURES

At the first visit, the cat had epiphora OD and facial dermatitis but no other abnormalities on physical and ophthalmic examinations. Computed tomography (CT)-dacryocystorhinography revealed partial obstruction of the NL duct secondary to stenosis near the distal root of the right maxillary third premolar (107). A digital three-dimensional (3D) model of the right maxilla and NL duct was created for inspection and virtual cannulation of the NL. The model was 3D printed and cannulation of the NL duct was rehearsed with various stent materials. Retrograde NL stenting with the guidance of a steerable angle-tipped hydrophilic guidewire was conducted following a paranasal incision. A urethral catheter was cannulated over the guidewire and maintained for 44 days.

RESULTS

The epiphora resolved immediately after stenting. At 21 days post-stenting, the cat developed acute bullous keratopathy secondary to self-trauma which was treated with a third eyelid flap. On the final follow-up communication with the owner at 210 days post-stenting, no epiphora or any other concerns were reported.

CONCLUSION

To the authors' knowledge, this is the first report of successful NL stenting and resolution of epiphora in a cat with a partial NL system obstruction.

Retrospective study identifying risk factors for dacryocystitis in pet rabbits

BACKGROUND

Dacryocystitis has been suggested to be a relatively common condition in pet rabbits and is often associated with concurrent disease. The aim of this study was to investigate potential risk factors associated with dacryocystitis in a pet rabbit population.

METHODS

A retrospective review of medical records from all rabbit cases evaluated at a single first opinion/referral UK exotics clinic between 2015 and 2018 was performed.

RESULTS

Dacryocystitis was identified in 55 of 821 rabbits (6.70%) examined over the study period. Of those rabbits with dacryocystitis, dental disease was found in 24 rabbits (45%), respiratory disease in 20 rabbits (38%), aural disease in seven rabbits (13%) and concurrent ocular disorders in 15 rabbits (23%). Breed status was found to be a significant risk factor, with Lionhead/Lionhead cross and Dwarf Lop/Dwarf Lop cross rabbits being more likely to have dacryocystitis.

CONCLUSION

These results suggest that a breed predisposition for dacryocystitis may exist, particularly for the popular Lionhead and Dwarf Lop rabbits, and veterinarians should advise clients on this accordingly.

Case series: Computed tomography (CT) demonstrates lacrimal canal involvement in koalas (Phascolarctos cinereus) with maxillary incisor dental disease

Dental disease is common in wild and captive koalas. Effective treatments are limited and dental disease may not be recognised until it is quite severe. We describe the appearance of varying severities of dental disease on computed tomography (CT) images in a case series of six koalas. This case series demonstrates the use of CT to detect both mild and severe dental disease in koalas. The study also documents the normal CT appearance of the nasolacrimal duct in the koala. The only clinical abnormality in koalas with the mildest dental disease was ocular discharge. Computed tomography findings associated with ocular discharge were periapical lysis of first maxillary incisors, lacrimal canal remodelling and subsequent nasolacrimal duct obstruction. Dental disease should be a differential diagnosis for ocular discharge in koalas and CT examination enables visualisation of early stages of dental disease.

Ophthalmologic Diseases of Small Mammals

Ophthalmic examination of small mammals follows the same principles as in other species. Reference values for tear production and intraocular pressure are provided. Conjunctivitis and epiphora is common in rabbits. Numerous infectious organisms have been isolated from rabbits with conjunctivitis. Dental disease can be a cause for conjunctivitis in rabbits. Treatment consists of topical and oral antimicrobial agents and irrigation of the nasolacrimal system. Underlying dental disease needs to be addressed. Ulcerative keratitis, corneal dystrophy, membranous occlusion of the cornea and eosinophilic keratitis are described. Encephalitozoon cuniculi can cause phacoclastic uveitis in rabbits. A break in the anterior lens capsule exposes lens protein with subsequent anterior uveitis and cataract formation. Cataract surgery can be performed to remove the affected lens. Glaucoma is inherited as an autosomal recessive trait in rabbits. Orbital disease in rabbits may be associated with dental disease. Treatment is often difficult due to the caseous nature of the abscessed material. The most common ophthalmic diseases seen in ferrets include conjunctivitis, corneal endothelial cell degeneration, cataract formation, retinal degeneration and orbital disease. Ophthalmic diseases in guinea pigs include conjunctivitis, dermoids, cataract and osseous metaplasia of the mesectodermal trabecular meshwork. Exophthalmos may be related to dental disease in guinea pigs and chinchillas. Chromodacryorrhea is seen in rats and mice associated with inflammation of the Harderian gland. Sialodacryoadenitis virus is a highly contagious virus that may cause exophthalmos, epiphora and keratoconjunctivitis. Ammonia vapors from soiled bedding can cause keratoconjunctivitis in hamsters.

Morbidity and mortality of domestic rabbits (Oryctolagus cuniculus) under primary veterinary care in England

Background

The domestic rabbit is a common pet species, but limited research exists on the health of pet rabbits. This study aimed to characterise common disorders of pet rabbits and reasons for mortality as recorded by veterinary practices in England.

Methods

This cross-sectional study covered anonymised clinical records of 6349 rabbits attending 107 primary veterinary care clinics.

Results

The median age was 3.2 years (interquartile range (IQR) 1.6–5.1), and the median adult bodyweight was 2.1 kg (IQR 1.7–2.6). The most common breed types were domestic (n=2022, 31.9 per cent), lop (1675, 26.4 per cent) and Netherland dwarf (672, 10.6 per cent). For those rabbits that died during the study period, the median age at death was 4.3 years (IQR 2.1–7.0). The most common causes of death were recorded as myiasis (prevalence 10.9 per cent, 95 per cent confidence interval (CI): 7.4 to 15.2), anorexia (4.9 per cent, 95 per cent CI: 4.0 to 10.4), recumbency/collapse (4.9 per cent, 95 per cent CI: 4.0 to 10.4) and ileus (4.3 per cent, 95 per cent CI: 3.5 to 9.5). The most prevalent specific disorders recorded were overgrown claw/nails (16.0 per cent, 95 per cent CI: 14.5 to 17.5), overgrown molar(s) (7.6 per cent, 95 per cent CI: 6.6 to 8.7), perineal soiling (4.5 per cent, 95 per cent CI: 3.7 to 5.4), overgrown incisor(s) (4.3 per cent, 95 per cent CI: 3.5 to 5.2) and ileus (4.2 per cent, 95 per cent CI: 3.4 to 5.0).

Conclusions

This study augments the limited evidence base on rabbit health and can assist veterinarians to better advise owners on optimal animal husbandry priorities.

Lop-eared rabbits have more aural and dental problems than erect-eared rabbits: a rescue population study

This research aimed to assess whether rabbits having lop ears, an artificially selected conformation, compromises welfare. We investigated the occurrence of aural and dental pathology in lop-eared compared with erect-eared rabbits. Thirty rabbits (15 lop-eared and 15 erect-eared) from a rabbit-only rescue shelter were examined. An otoscope was used to visualise the ear canals and mouth. Samples were taken from each ear to examine for mites, bacteria and yeast. Medical records were also examined. Lop-eared rabbits showed statistically significantly more frequent ear canal stenosis, higher scores of cerumen and erythema and more frequent potential pain response during ear examination, compared with erect-eared rabbits. We also found statistically significantly more frequent incisor pathology, molar overgrowth, molar sharpness, molar spurs and history of veterinary dental treatment in lop-eared compared with erect-eared rabbits. The effect sizes were often large. Age was not statistically significant between the lop-eared and erect-eared rabbit groups. Thus, lop-eared rabbits were at an increased risk of aural and dental pathology in this study. This brings into debate the ethics of breeding and buying lop-eared rabbits, as they are more likely to suffer conditions that negatively impact welfare, such as pain, and potentially deafness and difficulty eating.

Ocular Surface Disease of Rabbits

Rabbits have become a popular house pet that is encountered with increasing frequency in small animal veterinary practice. The unique anatomy of the rabbit predisposes them to developing surface ocular problems including the development of dacryocystitis, as well as conjunctivitis and keratitis. This article endeavors to give an updated outline of the various conditions affecting the rabbit ocular surface, with emphasis on diagnosis and treatment.

Pharmacokinetics of deflazacort in rabbits after intravenous and oral administration and its interaction with erythromycin

The pharmacokinetic of deflazacort after intravenous and oral administration and the effect of erythromycin on the disposition of deflazacort in rabbits were investigated. A parallel study was carried out in twelve rabbits. The plasma concentration-time profiles of deflazacort were determined after intravenous and oral administration of single dosages of 5 mg/kg in the presence and absence (baseline) of multiple dose erythromycin regimens. Plasma concentrations of 21-desacetyldeflazacort were determined by HPLC. Plasma concentration-time curves were analysed by compartmental pharmacokinetic and noncompartmental methods. The t_½λz values following intravenous and oral administration were 3.67 and 4.96 hr, respectively. The apparent volume of distribution at steady-state (V_ss ) was 4.08 ± 0.31 L/kg, this value indicates that deflazacort is widely distributed into the extravascular tissues. Moreover, bioavailability after oral administration of deflazacort (F = 87.48%) was high. Pharmacokinetic analysis after both routes of administration revealed a significant reduction in total body clearance, a significant increase in mean residence time, half-life and plasma concentrations of the steroid in the presence of multiple dose erythromycin. The results indicated the influence of the erythromycin on deflazacort disposition, which is consistent with a pharmacokinetic-type interaction in the elimination of the drug from the body. Moreover, this interaction should be considered to avoid adverse effects when using both drugs concomitantly.

Health survey of 167 pet rabbits (Oryctolagus cuniculus) in Finland

Only a limited amount of information is available about health status of pet rabbits. The aim of this study was to obtain data about the health status of pet rabbits considered healthy by the owners in Finland. Physical examination and lateral abdominal and lateral skull radiography were performed on 167 pet rabbits of which 118 (70.7 per cent) had abnormal findings in at least one examination. The most common findings were acquired dental disease (n=67, 40.1 per cent), vertebral column deformities and degenerative lesions (n=52, 31.1 per cent), skin disorders (n=28, 16.8 per cent) and eye disorders (n=12, 7.2 per cent). Vertebral column angulating deformities were significantly more common in dwarf lop rabbits (P≤0.001). The prevalence of health disorders was significantly higher in rabbits over three years of age of which 51 (82.3 per cent) had findings in at least one examination (P<0.05). Rabbits as prey animals hide their illness, which cause difficulties to owners to recognise health problems. Because of the high prevalence of clinical and radiological findings in apparently healthy pet rabbits, regular physical examinations are advised, especially for animals over three years old.

Biology and Diseases of Rabbits

Beginning in 1931, an inbred rabbit colony was developed at the Phipps Institute for the Study, Treatment and Prevention of Tuberculosis at the University of Pennsylvania. This colony was used to study natural resistance to infection with tuberculosis (Robertson et al., 1966). Other inbred colonies or well-defined breeding colonies were also developed at the University of Illinois College of Medicine Center for Genetics, the Laboratories of the International Health Division of The Rockefeller Foundation, the University of Utrecht in the Netherlands, and Jackson Laboratories. These colonies were moved or closed in the years to follow. Since 1973, the U.S. Department of Agriculture has reported the total number of certain species of animals used by registered research facilities (1997). In 1973, 447,570 rabbits were used in research. There has been an overall decrease in numbers of rabbits used. This decreasing trend started in the mid-1990s. In 2010, 210,172 rabbits were used in research. Despite the overall drop in the number used in research, the rabbit is still a valuable model and tool for many disciplines.

Tear production, intraocular pressure and conjunctival microbiota, cytology and histology of New Zealand rabbits (Oryctolagus cuniculus)

The purpose of this study was to establish reference values for selected ophthalmic diagnostic tests in New Zealand rabbits (Oryctolagus cuniculus). A total of 22 adult male rabbits were used. The ophthalmic tests included evaluation of tear production with Schirmer tear test 1(STT1) and Endodontic absorbent paper point tear test (EAPPTT) using two different commercial brand materials. Applanation tonometry, Culture of the conjunctival bacterial flora, , conjunctival cytology and conjunctival histology were also performed. Mean (±SD) for STT1, EAPPTTa, EAPPTTb and IOP was 7.27±2.51mm/min, 12.43±1.69mm/min, 15.24±2.07mm/min, 12.89±2.80mm Hg, respectively. Staphylococcus epidermidis, Staphylococcus sp. and Bacillus sp. were predominant. The cytological evaluation revealed the presence columnar epithelial cells, superficial squamous keratinized cells, lymphocytes, heterophils, red blood cells, mucus and bacteria. The histological analysis revealed a stratified epithelium, characterized by the presence of columnar epithelial cells with a large number of goblet cells. The reported data can be used for therapeutic or experimental purposes.

Eosinophilic keratoconjunctivitis in two rabbits

The purpose of this case report is to describe the clinical course and cytologic findings, treatment, and outcome of eosinophilic keratoconjunctivitis in two rabbits. Ophthalmic examination revealed ocular discharge, dacryocystitis, blepharitis, conjunctivitis, white conjunctival and corneal plaques, corneal vascularization, and stromal infiltration with different degrees of severity in each case. In case 2 there was also ulcerative disease of the cornea. Computerized tomography scan of the head, corneal biopsy for histopathologic examination with additional Luna and Giemsa stain were performed in case 2 and conjunctival as well as corneal specimens were obtained for bacteriologic culture and cytologic examination in case 1. Based on test results, a diagnosis of eosinophilic keratoconjunctivitis was made in case 2 and a tentative diagnosis of eosinophilic keratoconjunctivitis was made in case 1. Response to treatment with a topical steroid and topical cyclosporin was supportive of the diagnosis in both cases and shared many similarities with the response to treatment previously described in cats. Eosinophilic keratitis should be considered as part of a differential diagnosis list in rabbits with a history of keratitis.