






































Type of the Paper (Article


 

  

 

 
Cluj Vet J 2024, 29, 2 http://clujveterinaryjournal.ro 

Article 

Microbiology of Dental Disease in Pet Rabbits  

Tamara Titanilla Kiss-Pruteanu1*, Lucia Bel1, Cosmina Dejescu1, R. Lacatus1, Mariana Tătaru1, S.M. Mârza1, I. Papuc1* 

1 Faculty of Veterinary Medicine, University of Agricultural Sciences and Veterinary Medicine, 400372, 
Cluj-Napoca, Romania; tmr_kss@yahoo.com, lucia.bel@usamvcluj.ro, cosminadejescu@yahoo.com, 
radu.lacatus@usamvcluj.ro, mariana.tataru@usamvcluj.ro, sorin.marza@usamvcluj.ro, 
ionel.papuc@usamvcluj.ro  
* Correspondence: ionel.papuc@usamvcluj.ro, tmr_kss@yahoo.com 

 
Abstract:. Maintaining the health and hygiene of the oral cavity is an essential condition to prevent dental diseases, both in humans 
and animals.This study aimed to present the importance of prevention techniques and treatment options for dental disease in pet 
rabbits. The research was focused on 16 rabbits that had been diagnosed with dental disease based on clinical and paraclinical 
examination, we obtained samples from the dental injury site using a sterile cotton swab and followed up with bacteriological 
examination and antibiotic sensitivity testing for identifying the bacteria and the resistances. Out of 16 samples sent to the laboratory 
for testing, 4 were negative (25%), showing no bacterial growth, from the rest of the samples the following bacterial strains were 
identified: 18,75% Staphylococcus spp., 18,75% Streptococcus spp., 6,25% Streptococcus β hemolytic, 6,25% Pseudomonas aeruginosa, 6,25% 
Klebsiella spp. 3 cases presented with multiple-strain infection as follows: 6,25% Streptobacillus spp. and Klebsiella spp.; 6,25% Proteus 
spp. and Streptococcus spp.; 6,25% Pseudomonas spp. and Streptococcus spp. After obtaining the antibiotic sensitivity test results, we 
found that the most efficient drug was amikacin, no bacteria presented resistance to this medicine, and it was followed by 
trimethoprim/sulfa (TMPS) and ciprofloxacin. All the identified bacterial strains presented resistance to amphotericin and 
clindamycin. Antimicrobial resistance and the limited availability of veterinary-use-approved drugs constitute strong arguments 
that sustain the importance of this study in the management of dental disease in pet rabbits.    

 
Keywords: rabbits, dental disease, bacteriology, antimicrobial resistance, treatment   

   
 

1. Introduction 
Periodontal and endodontic disease in pet rabbits manifests in the form of periapical 

infections which often can lead to osteomyelitis and the appearance of odontogenic 
abscesses. In case of malocclusion, the pressure exerted on the occlusal surface of the 
cheek teeth raises the susceptibility to the occurrence of acquired dental disease. Crown 
elongation creates more interdental space and weakens the alveolar ligaments which can 
be invaded by pathogenic microflora. Jaw abscesses present a major health issue, they are 
considered inflammatory reactions caused by pyogenic strains of bacteria that are 
immune to phagocytosis due to the polysaccharides residing in the capsule of the 
abscesses [1, 2]. Odontogenic abscesses are frequently localized in the submandibular or 
maxillofacial region if the oral mucosa presents lesions caused by dental spikes or the 
periapical infection cannot be contained by the self-defense mechanisms of the host [3].  
Mandibular abscesses usually appear due to intra-alveolar infections originating at the 
site of incisors or cheek teeth. The exposed apex of the tooth is the most affected zone and 
they often are presented with retrograde displacement. These types of infections are 
rarely detected in time because the rabbits do not manifest clinical symptoms at this stage. 
The subtle intraosseous changes can be detected only by radiological examination or by 
the use of computed tomography. Progressive bone resorption caused by the pyogenic 
bacteria will lead to the formation of typical mandibular abscesses around the severely 

damaged and infected incisor or molar with noticeable growth issues. The whole mandible can be compromised 
and destroyed in extreme cases [4]. A frequently met complication in these cases is the hematogenous or 

Received: 08.04.2024 

Accepted: 03.06.2024 

Published: 24.06.2024 

DOI: 10.52331/1sh8e648 

 

 

 

Copyright: © 2024 by the authors. 

Submitted for possible open-access 

publication under the terms and 

conditions of the Creative Commons 

Attribution (CC BY) license 

(http://creativecommons.org/licenses

/by/4.0/). 

mailto:lucia.bel@usamvcluj.ro
mailto:cosminadejescu@yahoo.com
mailto:radu.lacatus@usamvcluj.ro
mailto:mariana.tataru@usamvcluj.ro
mailto:ionel.papuc@usamvcluj.ro
mailto:ionel.papuc@usamvcluj.ro


Cluj Vet J 2024, 29, 2 2 of 43 
 

lymphatic transmission of the infection that can lead to the apparition of secondary abscesses in the thoracic or 
abdominal cavities, in extreme cases the infection can also reach the cranial cavity [2]. Rabbits affected by 
intrathoracic suppurative processes will manifest dyspnea, general weakness, and apathy. Superficial abscesses 
can also appear and they create large cavities under the skin after they reach maximal size the skin will tear and 
a fetid, purulent secretion will drain to the exterior of the body. In an advanced stage of malocclusion, the 
superior molars and the last superior premolar due to the continuous growth of the rabbit teeth will become 
longer and will start presenting curvature towards the cheeks causing the apex to also be displaced and reach 
the retro-orbital zone. The apexes that reach the immediate proximity of the eyeball can cause local irritation, 
pain, and general discomfort during mastication. If these irritating factors persist and are associated with an 
apical infection, they can lead to the formation of retrobulbar abscesses. The infection around the orbital region 
can extend from the apex of the teeth to the soft tissue surrounding the eye and also can include the lacrimal 
gland. Inflammation of the peri and retro-orbital space presses the eyeball out of the socket causing the third 
eyelid to prolapse. Incomplete closing of the eyelids due to the eye protrusion can further lead to keratitis, and 
after a few days if left untreated, depending on the grade of the protrusion, uveal tract infection can appear. All 
these factors tailored together can cause panophthalmia or ptosis of the eye [4]. Treating abscesses in rabbits 
can be a challenge for practitioner veterinarians due to the encapsulated nature and the poor level of penetration 
of antibiotic drugs into the abscess cavity. Management of these abscesses usually consists of surgical ablation 
followed by antibiotic therapy both locally and systemic [5]. Excessive use of antibiotics concerns both human 
doctors and veterinarians because of the rising levels of resistant bacteria which became a global problem for 
all the species [5]. 

All the aforementioned elements highlight the importance of the microbiological examination as a step 
that cannot be skipped in establishing an etiologic diagnosis and an efficient treatment plan. Even if these 
infections appear secondarily, they need to be treated accordingly since many bacterial strains identified in 
dental disease also carry zoonotic potential and that is notable in the global context of antibiotic resistance.    
           
2. Materials and Methods 

In this study, 16 dwarf breed pet rabbits were included , males and females with ages between 2 and 7 
years with an average of 5 years, the age of the animals was determined by declaring it by the owners, which 
were diagnosed with acquired dental disease. The applied methods consisted of clinical and paraclinical 
examination. Initially, the rabbits underwent a general clinical examination followed by a rigorous examination 
of the oral cavity and the teeth. The samples were collected from all 16 pet rabbits presented with dental disease 
and then sent to a private laboratory for testing The paraclinical examination included the bacteriologic and 
bacterioscopic examination of the collected samples, small portion of the excised abscess capsule and the whole 
extracted tooth, using the following instruments: sterile cotton swab, heparinized vacutainer tubes, Columbia 
agar with 5% sheep blood, MacConkey agar medium, Mueller-Hinton agar dish, antibiotic disc reagent, 
insemination loop, Bunsen gas burner, incubator, dyes for Gram staining, microscope and slides. Columbia 
Agar with 5% Sheep Blood is a highly nutritious universal medium for the isolation and cultivation of fastidious 
and non-fastidious microorganisms from clinical samples. McConkey for the identification of the bacterial 
strain Escherichia Coli, knowing that the rabbit is a cecotroph. Dental infections in leporidae caused by 
anaerobic germs are limited, and most of the drugs used have digestive side effects and cause post-therapy 
dysbiosis.  

The collection of the biological samples was done during surgery with the help of a sterile cotton swab 
from the abscess cavity and soft tissue, bone, tooth, and capsule fragments were also extracted. The samples 
were collected in the sterile swab container and heparinized vacutainers and kept refrigerated at 2-4°C for 24 
hours. The microbiological examination took place in the laminar air flow chamber to provide aseptic 
conditions, the samples were inseminated on the blood and MacConkey agar mediums (Figure 1). The petri 
dishes were incubated at 37°C temperature for 24 hours. Slides were prepared from bacterial colonies grown in 
the culture medium, and Gram staining was performed to enable bacterioscopic examination than bacterial 
colonies were then isolated for antibiotic sensitivity testing using the Kirby-Bauer disc-diffusion technique. 
Each isolated strain was suspended in nutrient broth up to 0.5° optical density using the McFarland scale. The 
dishes containing Mueller-Hinton agar then were flooded with the prepared broth. The excess amount of 
nutrient broth was eliminated and the dish was left to dry. This was followed by placing the antibiotic disc 



Cluj Vet J 2024, 29, 2 3 of 43 
 

reagent on the agar. The antibiotic drugs used in the sensitivity testing are highly relevant in small mammals' 
clinical activity. The prepared Mueller-Hinton agar dishes were then kept again for 24 hours at 37°C 
temperature. The reading of the antibiogram (Figure 2) consists of measuring the diameter in millimeters of the 
total inhibition zone. The results classify in sensitive, resistant, partial inhibition, and partial inhibition with 
resistant colonies. Antibiotics used for testing (microtablets and antibiotic strength) was: amoxicillin 30 mcg (30 
μg) AML, TMPS – 25 mcg (23.75 mcg/1.25 mcg) – Co-trimoxazole (Suslfa/trimethoprim) COT, gentamicin 10 
mcg GEN, cephalexin 30 mcg CL, marbofloxacin 5 mcg MAR, enrofloxacin – 10 mcg ENR , penicillin G - 10 mcg 
P, cefotaxime - 30 mcg CTX, ciprofloxacin – 5 mcg CIP, amikacin – 30 mcg AK, clindamycin – 2 mcg CD, 
amphotericin B – 20 mcg  AMB, doxycyclin – 30 mcg DXT, polymixin B – 50U PB, erythromycin – 10 mcg E.. 
The owners of the rabbits signed their agreement to this study.       
 
 

 
Figure 1. Columbia agar with 5% sheep blood at 24 

hours after insemination 

Figure 2. Antibiogram on Mueller-Hinton agar 

 

3. Results 

Out of 16 samples sent to the laboratory for testing, 4 were negative (25%), showing no bacterial growth, 
from the rest of the samples the following bacterial strains were identified: 18,75% Staphylococcus spp, 18,75% 
Streptococcus spp, 6,25% Streptococcus β hemolytic, 6,25% Pseudomonas aeruginosa, 6,25% Klebsiella spp. In 
the aforementioned 8 cases, only one bacterial strain was identified but 3 cases were presented with multiple-
strain infection as follows: 6,25% Streptobacillus spp. and Klebsiella spp.; 6,25% Proteus spp. and 
Streptococcus spp.; 6,25% Pseudomonas spp. and Streptococcus spp.  (Figure 3).  To identify the bacterial 
strains Klebsiella spp. and Proteus spp., the special medium TSI (Triple Sugar Iron) was used, for the species 
Proteus spp., Pseudomonas spp., Staphylococcus spp. the UTI medium (Chromogenic UTI medium) was used, and 
for bacterial strain Streptococcus ssp., Columbia agar medium with the addition of 5% ram blood was used. Out 
of all the antibiotics used in the sensitivity testing, amikacina was the most efficient, no strain was resistant to 
this drug. The second most efficient drug was trimethoprim/sulfamethoxazole (TMPS) followed by 
ciprofloxacin. The identified bacterial strains presented no sensitivity at all to amphotericin and clyndamycin 
(Figure 4). The interpretation of the antibiogram was done according to EUCAST requirements. The results of 
the microbiological and sensitivity testing including the grade of the resistance can be found in Table 1. 



Cluj Vet J 2024, 29, 2 4 of 43 
 

 
Figure 3. Results of the microbiological examination 

 

 
Figure 4. Results of the antibiotic sensitivity testing and drug efficiency 

 

 

 

25.00%

18.75%

18.75%

6.25%

6.25%

6.25%

6.25%

6.25%
6.25%

Negative

Staphylococcus spp.

Streptococcus spp.

Streptococcus β hemolytic

Klebsiella spp.

Pseudomonas aeruginosa

Streptobacillus spp. + Klebsiella spp.

Proteus spp. + Streptococcus spp.

2%

13%

11%

11%

2%
4%

6%6%

12%

21%

6%
4%

2%

Amoxicillin

TMPS

Gentamicin

Cephalexin

Marbofloxacin

Enrofloxacin

Penicillin

Cefotaxime

Ciprofloxacin

Amikacin

Doxycyclin

Polimixin

Erythromycin

Asus
You have the name writtent above the diagram. Maybe erase it from there?

PC
Done



Cluj Vet J 2024, 29, 2 5 of 43 
 

Table 1. Antibiotic sensitivity test results  

Nr 

  Antibiotic 

 

 

 

Bacterial strain 

A
m

oxicillin 

T
M

PS 

G
entam

icin 

C
ephalexin 

M
arbofloxacin 

E
nrofloxacin 

Penicillin 

C
efotaxim

e 

C
iprofloxacin 

A
m

ikacin 

C
lindam

ycin 

A
m

photericin 

D
oxycyclin 

Polym
ixin 

E
rythrom

ycin 

1 
Staphylococcus 

spp 
34 22 21 40 21 23 38 24 - - - - - - - 

2 
Staphylococcus 

spp 
- - 27 21 - 20 R 21 15 26 - - - - - 

3 Streptococcus spp - 18 22 - - - - - R 20 R R 17 - - 

4 
Staphylococcus 

spp 
- 31 26 - - - - R 21 27 - - 22 - - 

5 
Pseudomonas 

aeruginosa 
- 11 17 R - - - R R 21 - R - R - 

6 Streptococcus spp - 16 - R - - R - 12 21 - R - 18 - 

7 NEGATIVE  

8 NEGATIVE  

9 NEGATIVE  

10 

Pseudomonas 

aeruginosa, 

Streptococcus spp 

R 15 - 14 - - R R R 20 R - R - 25 

11 
Streptobacillus 

Klebsiella spp 
- 20 - 21 - - 21 27 29 21 R R 21 - - 

12 Klebsiella spp R R - R R R - R 27 19 - - R - - 

13 
Proteus spp 

Streptococcus spp 
R R R R R R R R 20 10 R R R R R 

14 
Streptococcus β 

hemolytic 
R - - 21 - - R - 18 19 - R - 17 - 

15 Streptococcus spp R R 27 35 - - 26 R - 22 - - - - - 

16 NEGATIVE  

 

4. Discussion 

Data from the literature regarding periodontal infections in rabbits show that the very first etiologic agent 
involved was the strain Actinomycetes from the order Antinomycetales. This is a Gram-negative prokaryotic 
organism identified by Frostowicz and Frelik in the Chadronian (Eocene) lagomorph, Megalus from Pipestone 
Springs, Montana, United States [6]. 

In our study, we did not identify any of these microorganisms. Tyrell and colleagues identified[7] in his 
study on 12 rabbits a wide range of bacterial strains involved in dental pathology causing mandibular and 
maxillofacial abscesses in rabbits. These were the following: Fusobacterium nucleatum, Prevotella heparinolytica, 



Cluj Vet J 2024, 29, 2 6 of 43 
 

Prevotella spp., Peptostreptococcus micros, Actinomyces israelii and Arcanobacterium haemolyticum [7]. Another study 
conducted by Gardhouse and team [8] on a significant number of 48 rabbits shows identified aerobic bacteria: 
Pseudomonas aeruginosa, Streptococcus spp., Staphylococcus spp., as well as anaerobic bacteria like Fusobacterium spp., 
Peptostreptococcus spp., Bacteroides spp., involved in odontogenic abscess formation. Mixed infections containing 
anaerobic and aerobic bacteria in 73% percent of the cases also contained 3 or more bacterial strains [8]. The 
results obtained by us in this study did not confirm the data from the specialized literature regarding the 
pathogenic bacterial species that caused the dental infections described in the two studies, with the exception of 
Streptoccus spp. and Pseudomonas spp. strains.  

Treatment protocols are limited in dental disease in rabbits complicated by anaerobic bacteria due to the 
restrained compatibility of drugs available to rabbits and they can cause secondary digestive side effects and 
dysbiosis following treatment so the patients need to be monitored carefully. Studies confirm that 
aminopenicillins, clindamycin, and erythromycin administered orally can cause severe enterotoxemia and 
dismicrobism [8]. 

Metronidazole, chloramphenicol, and penicillin G can be used in parenteral administration as a systemic 
treatment for anaerobic bacterial infections. Azithromycin also proved efficient in these types of infections 
according to literature [15]. Metronidazole is a great option for treating dental infections in rabbits due to its 
potential to easily penetrate tissues, including bone tissue, and has a satisfactory absorption rate when 
administered orally. The recommended dosage is 20 mg/kg per dose once a day at least for 6 weeks after orofacial 
surgery, based on the antibiotic sensitivity test results [9]. 

Ward’s study[10] describes using polymer gel based on doxycycline (Doxirobe™) as being an ideal 
alternative to fill the cavities or fistulas created by abscesses. The physical properties of the gel allow us to apply 
the gel in liquid form and then while it solidifies it cuts off the communication between the organism and the 
exterior environment while distributing the antibiotic drug in the affected zone. It is easily removed during the 
control of the patient or replaced if needed [10].  

Craniometric measurements can also play an important role in identifying rabbits predisposed to develop 
dental disease either acquired or hereditary and also can be a factor in selecting individuals for breeding dwarf 
pet rabbits [11].  
In topical treatment of extensive bone defects in patients presenting dental disease who underwent multiple 
teeth extractions, measuring the skull alongside radiography and computed tomography examinations can help 
put in place a proper treatment protocol [11]. In these cases, there are multiple available solutions like calcium 
hydroxide or antibiotic-impregnated polymethylmethacrylate (AIPMMA). The antibiotic-impregnated beads in 
many cases succeed in stabilizing the bone structure and controlling the infection, but in extensive bone defects, 
with larger cavities, these beads have a lower efficiency rate [10].   

AIPMMA beads are a recommended therapy for creating antibiosis in extensive bone damage due to 
multiple teeth extraction and abscess extirpation. The polymethylmethacrylate will be covered in connective 
tissue in a short amount of time and the antibiotic will only penetrate a 3 mm distance from the bead, so placing 
this inside the capsule of an abscess is not efficient [12]. The impregnated antibiotic is chosen based on the 
antibiotic sensitivity test results.  
Based on our results from this study, all our patients presenting with dental disease received medication. The 
antibiotic administration protocol was based on the study by Fisher and Jenifer Graham, (2018) and the study 
by Taylor et al., (2010) applied to rabbits with dental abscesses [13, 14]. The therapy protocol was dependent on 
the grade of the sensitivity shown in the bacterial strains with the selected antibiotic drug in the following dosage: 
amikacin 10 mg/kg IV or SC administration once a day for a minimum of 10 days, 



Cluj Vet J 2024, 29, 2 7 of 43 
 

trimethoprim/sulfamethoxazole 30 mg/kg PO twice a day for 10 to 14 days and ciprofloxacin 15 mg/kg twice a 
day for 10-14 days. Patients that presented different sensitivity test results were treated with doxycycline 4mg/kg 
PO twice a day for two weeks, penicillin G at 40000 U/kg IM once a day for 10 days, enrofloxacin 5 mg/kg PO or 
SC twice a day for 10 days and marbofloxacin at 2 mg/kg SC once a day for 7-10 days. We did not use 
amphotericin nor clindamycin at all in our study due to bacterial resistance.   

5. Conclusions 

Our study reconfirms the major importance of bacteriological examination and antibiotic sensitivity testing 
in identifying the etiological agents and efficiently treating dental disease in pet rabbits.   

Our results shine a light on the significance of the sensitivity of bacterial strains that cause apical infections 
in pet rabbits to correctly manage the treatment containing antibiotics, an aspect that today is not routinely 
performed in all veterinary medical offices. In the oral cavity of rabbits, a wide range of bacteria already exists 
and because they may carry zoonotic potential, they present a high risk for the owners as well. Species from the 
genus Streptococcus spp. and Staphylococcus spp., are commensal and opportunistic species that can cause 
respiratory tract infections in people with a weakened immune system. 

Considering the growing number of pet rabbits and their predisposition to dental disease and odontogenic 
abscess formation, an accurate treatment plan based on medical evidence is the most important in ensuring good 
health and wellbeing in the rabbit patient.  
 

Author Contributions: Conceptualization, K-P.T.T. and I.P.; methodology, investigation, L.R., P.R.C. and M.S.M.; 
writing—original draft preparation, K-P.T.T.; writing—review and editing, M.T., L.B. and C.D.; supervision, I.P.; All 
authors have read and agreed to the published version of the manuscript. 

Institutional Review Board Statement: Ethical review and approval were waived for this study due to preexisting 
conditions in the dogs, which included recommended euthanasia based on previously obtained consent from the 
owners. 

Data Availability Statement: For further information, please contact the corresponding author via email. 

Conflicts of Interest: The authors declare no conflict of interest. 

References  
 

1. Deeb, B., Update for veterinary practitioners on pasteurellosis in rabbits. J. Small Exotic Anim. Med., 1993, 
Volume 2, 112−13. 

2. Harcourt-Brown, F.M., Abscesses. In: Textbook of Rabbit Medicine (ed. Harcourt-Brown, F.M.), Butterworth, 
London, 2002, Pages 206−23. 

3. Hamlin, J., Causes, examination and treatment of dental disease in rabbits. The Veterinary Nurse, 2013, 4(3):156-
166. 

4. Böhmer Estella, Dentistry in rabbits and rodents. John Wiley & Sons, 2015. 
5. Hedley, J., Antibiotic usage in rabbits and rodents. In Practice, 2018, 40(6), pp.230-237. 
6. Fostowicz-Frelik, L., Frelik, G. J., Earliest record of dental pathogen discovered in a North American Eocene 

rabbit. Palaios, 2010, 25(12): 818-822. 
7. Tyrrell, K.L., Citron, D.M., Jenkins, J.R. and Goldstein, E.J., Periodontal bacteria in rabbit mandibular and 

maxillary abscesses. Journal of clinical microbiology, 2002, 40(3):1044-1047. 
8. Gardhouse, S., Sanchez-Migallon Guzman, D., Paul-Murphy, J., Byrne, B.A., Hawkins, M.G., Bacterial isolates 

and antimicrobial susceptibilities from odontogenic abscesses in rabbits: 48 cases. Veterinary Record, 2017, 
181(20):538-538. 



Cluj Vet J 2024, 29, 2 8 of 43 
 

9. Lord, B., Dental disease in the rabbit Part 3: Treatment and prognosis of dental disease. Companion 
Animal, 2011, 16(7):46-49. Part 4: Diagnosis and management of odontogenic abscesses. UK Vet Companion 
Animal, 16(8):42-49. 

10. Ward, M.L., Diagnosis and management of a retrobulbar abscess of periapical origin in a domestic 
rabbit. Veterinary Clinics: Exotic Animal Practice, 2006, 9 (3):657-665. 

11. Kiss-Pruteanu Tamara Titanilla, Lucia Bel, Cosmina Dejescu, R. Purdoiu, R. Lacatus, Mariana Tătaru, S.M. 
Mârza, Camelia Munteanu, Olivia Petrescu, I. Papuc, Craniometric measurements of the flemish giant rabbit 
and the dwarf pet rabbit skull (Oryctolagus Cuniculus Domesticus), Rev Rom Med Vet, 2024, 34 | 1: 51-58. 

12. Meredith, A., Rabbit dentistry. European Journal of Companion Animal Practice, 2007, 17(1):55-62. 
13. Fisher P., Graham Jennifer, Chapter 10 - Rabbits, Editor(s): James W. Carpenter, Christopher J. Marion, Exotic 

Animal Formulary (Fifth Edition), W.B. Saunders, 2018, Pages 494-531. 
14. Taylor, W.M., Beaufrère, H., Mans, C. and Smith, D.A., Long-term outcome of treatment of dental abscesses 

with a wound-packing technique in pet rabbits: 13 cases (1998–2007). Journal of the American Veterinary 
Medical Association, 2010, 237(12):1444-1449.

 


