Bacterial Dermatitis in Lagomorphs

Disease Summary

• Bacterial infection of the skin occurs when:
  • the integrity of the skin surface has been broken;
  • chronic exposure to moisture has macerated the skin; 
  • there has been an alteration of the normal bacterial flora; 
  • there has been impairment of the circulation; or
  • immunocompetency has been compromised. 

(B609.2.w2)

The three most common locations of dermatitis in the domestic rabbit are:

• Moist dermatitis of the dewlap
• Facial dermatitis
• Perineal dermatitis

(B600.9.w9, B609.2.w2)

Alternative Names (Synonyms)

• Moist dermatitis (B614.15.w15)
• Superficial pyoderma (B600.9.w9)
• Slobbers (chin or ventral neck dermatitis) (B602.19.w19, B604.5.w5)
• Sore dewlap (B608.21.w21)
• Wet dewlap (B604.5.w5)
• Urine scald (perineal dermatitis) (B602.19.w19)
• Vent scald (perineal dermatitis) (B64.22.w8)
• Hutch burn (perineal dermatitis) (B64.22.w8, B602.19.w19, B604.5.w5)
• Blue fur disease (moist dermatitis of dewlap) (B601.13.w13)

See also: 

• Dermatophilosis in Bears and Lagomorphs
• Necrobacillosis in Lagomorphs
  • This involves more extensive invasion and tissue destruction. (B614.15.w15)

• Staphylococcosis (with special reference to Waterfowl, Hedgehogs, Bears and Lagomorphs)
• Treponematosis in Lagomorphs

Disease Type

Infectious/Non-Infectious Agent associated with the Disease

• Staphylococcus aureus
  • This is a common pathogen in superficial pyoderma in the rabbit. (B600.9.w9, B609.2.w2)
  • It can be isolated from all over the body in rabbits but is especially prevalent in the ears and perineum. (B600.9.w9)
  • There are many different phage types and biotypes that are related to virulence. (B600.9.w9)
• Staphylococcus warneri
  • This is a common pathogen in secondary bacterial dermatitis of Lepus timidus - Mountain hare. (J1.41.w6)
• Pseudomonas aeruginosa
  • Particularly in farmed rabbits that are kept in intensive conditions. (B600.9.w9)
  • Can cause a moist dermatitis of the dewlap (or any skin folds) which may be found in rabbits that are kept in damp conditions. (B600.9.w9, B602.19.w19, B606.4.w4, B615.6.w6, J213.4.w4)
  • Pyocyanin is a pigment that is produced by some strains of this bacteria and stains the fur blue-green. Several toxins can also be produced by this organism and this can lead to dermal necrosis and in severe cases, death. (B604.5.w5)
• Pasteurella multocida
  • This is the commonest pathogen in purulent skin conditions. It can be isolated in the nares of healthy rabbits and then spread to other parts of the body during grooming. (B600.9.w9)
  • It is often cultured from abscesses and is also a cause of respiratory infections. (B600.9.w9)
• Fusobacterium necrophorum
  • Particularly in farmed rabbits that are kept in intensive conditions. (B600.9.w9)
  • Causes Necrobacillosis or "Schmorls disease" which results in necrosis, ulceration and abscessation. (B600.9.w9)
• Dermatophilus congolensis
  • Infection with this bacterium is reported to occur in wild rabbits in North America. (B209.28.w28c)
  • This Gram-positive bacterium has an unusual fungus-like morphology and life-cycle. (B209.28.w28c)
  • See: Dermatophilosis in Bears and Lagomorphs

Infective "Taxa"

• Dermatophilus congolensis
• Fusobacterium necrophorum
• Pasteurella multocida
• Pseudomonas aeruginosa
• Staphylococcus aureus

Non-infective agents

Physical agents

References

Disease Author

Referees

Major References / Reviews

Code and Title List

Other References

Code and Title List

Detailed Clinical and Pathological Characteristics

Clinical Characteristics

The skin under the chin and around the throat can become sore and infected particularly if it is continually wet. (B600.9.w9)

History

• There may be a history of ptyalism, anorexia, dental disease, ocular or nasal discharge. (B609.2.w2)

Clinical examination findings

• Alopecia 
• Erythema 
• Skin ulceration and necrosis 
• Matted fur 
• Thickened, enlarged skin folds 
• Variable crusts
• Always carry out a thorough oral examination as ptyalism is the commonest cause and may be due to:
  • Fractured teeth 
  • Lodged food between the teeth and/or gingival mucosa. 
  • Malocclusion that is causing sharp points on the crowns that penetrate the oral mucosa. 
• Green skin or fur that is often clumped together or spiked: this may be seen if Pseudomonas aeruginosa has caused a secondary infection.

(B601.13.w13, B602.19.w19,  B606.4.w4, B608.21.w21, B609.2.w2)

FACIAL DERMATITIS

History

• There may be a history of epiphora, dental disease, ocular or nasal discharge, or exophthalmia. (B609.2.w2)

Clinical findings

• Bilateral or unilateral alopecia. 
• Crusts 
• Matted fur around the eyes, cheeks, and/or nasal rostrum. 
• The superficial pyoderma may be secondary to chronic epiphora or ocular discharge. 
• Ptyalism 
• Nasal discharge 
• Ocular discharge 
• Anorexia 
• Exophthalmia 

(B602.19.w19, B609.2.w2)

History

• There may be a history of polydipsia/polyuria, obesity, lower urinary tract disease, intermittent diarrhoea, lameness, reluctance to move, uneaten caecotrophs, or poor sanitation. (B609.2.w2)

Clinical findings

• Matted fur or alopecia that may extend from the perineal region to the inner thighs and abdomen. 
• The fur may be matted with caecotrophs or faeces or it may be urine soaked. 
• The skin in this area may be ulcerated and erythremic.
• Necrotic debris and purulent exudate may be present, particularly in rabbits that have deep perineal folds. 
• This can extend down the medial thighs to the hocks. (B600.9.w9)
• There may be fly strike. 
• Depending on the underlying cause there may be:
  • Obesity 
  • Musculoskeletal pain 
  • Palpable sand in the urinary bladder

(B602.19.w19, B609.2.w2)

OTHER BODY REGIONS AFFECTED BY DERMATITIS

• Other areas of the rabbit are less commonly affected compared to the dewlap, face or perineal regions and are most likely secondary to trauma or ectoparasites. (B609.2.w2)
• For pododermatitis see: Ulcerative Pododermatitis. 

Incubation

• --

Mortality / Morbidity

• --

• Very common in pet rabbits (Oryctolagus cuniculus domesticus - Domestic European rabbit). (B609.2.w2)

Pathology

• Inflammatory reaction - pyogranulomatous or suppurative. (B609.2.w2)

Gross pathology

• Partial alopecia, necrosis and ulceration of the affected skin. (B614.15.w15)

Histopathology

• Cellular elements of both chronic and acute inflammation may be found in the tissues around the ulceration. 
• There may be haematogenous and lymphatic extension especially to the pulmonary and ventral cervical lymph nodes. 

(B614.15.w15)

Human Health Considerations

Disease has been reported in either the wild or in captivity in:

• Leporidae - Rabbits and Hares (Family)
• Staphylococcus warneri is a common pathogen in secondary bacterial dermatitis of Lepus timidus - Mountain hare. (J1.41.w6)

Further information on Host species has only been incorporated for species groups for which a full Wildpro "Health and Management" module has been completed (i.e. for which a comprehensive literature review has been undertaken). Host species with further information available are listed below:

Host Species List

• Leporidae - Rabbits and Hares (Family)
  • Lepus timidus - Mountain hare
  • Oryctolagus cuniculus domesticus - Domestic European rabbit

(List does not contain all other species groups affected by this disease)

Disease has been specifically reported in Free-ranging populations of:

• Staphylococcus warneri is a common pathogen in secondary bacterial dermatitis of Lepus timidus - Mountain hare. (J1.41.w6)

Further information on Host species has only been incorporated for species groups for which a full Wildpro "Health and Management" module has been completed (i.e. for which a comprehensive literature review has been undertaken). Host species with further information available are listed below:

Host Species List

• Lepus timidus - Mountain hare

(List does not contain all other species groups affected by this disease)

General Information on Environmental Factors/Events and Seasonality

• --

Regions / Countries where the Infectious Agent or Disease has been recorded

• --

Regions / Countries where the Infectious Agent or Disease has been recorded in Free-ranging populations

• --

General Information on Investigation / Diagnosis

• Skin scrapings (B609.2.w2)
• Culture and sensitivity (B600.9.w9, B608.21.w21, B609.2.w2)
  • Submit samples of exudate or skin. (B602.19.w19)
  • Frequently positive for Staphylococcus aureus but other organisms may be identified. (B609.2.w2)
  • Useful for directing the antibiotic therapy. (B609.2.w2) 
• Skin biopsy
  • rule out neoplasia if there is a suspicion of this. (B609.2.w2)
• Dermatophyte culture (B609.2.w2)
• Radiography
  • For dewlap or facial dermatitis: 
    • This needs to be performed under general anaesthesia. (B609.2.w2)
    • Skull radiographs are useful in identifying the extent and type of dental disease. (B602.19.w19, B609.2.w2)
  • For perineal dermatitis:
    • Useful in identifying the underlying cause, e.g. osteoarthritis, urinary tract disease, spinal lesions. (B600.9.w9, B602.19.w19, B609.2.w2)
• Ultrasonography
  • Used to diagnose underlying gastrointestinal or urinary disorders. (B609.2.w2)
• CBC / Biochemistry / Urinalysis
  • These tests may be useful in identifying the underlying cause, for example, causes of diarrhoea, polydipsia/polyuria, or urinary tract infection. (B602.19.w19, B609.2.w2)
  • CBC changes purely due to pyoderma alone are not often present. (B609.2.w2)
• See: Clinical Pathology of Lagomorphs

• Environmental Assessment
• History & Documentation
• Physical Examination of Mammals
• Necropsy of Mammals
• Imaging in Lagomorph Diagnosis and Treatment
• Clinical Pathology of Lagomorphs
• Chapter 2 - B36 Field Manual of Wildlife Diseases - Specimen Collection and Preservation
• Chapter 3 - B36 Field Manual of Wildlife Diseases - Specimen shipment
• Appendix A - B36 Field Manual of Wildlife Diseases - Sample specimen history form

Similar Diseases (Differential Diagnosis)

• For other specific causes of bacterial dermatitis see also:
  • Dermatophilosis in Bears and Lagomorphs
  • Necrobacillosis in Lagomorphs
  • Staphylococcosis (with special reference to Waterfowl, Hedgehogs, Bears and Lagomorphs)
  • Treponematosis
  • Ulcerative Pododermatitis

Alternative causes of skin disease which should be considered in the differential diagnosis of bacterial dermatitis in rabbits include:

• Dominant rabbits chew or pull the hairs on submissive rabbits. This behaviour may not be observed by owners.
• Self-barbering is often a craving for fibre that is seen in rabbits that are fed a diet deficient in coarse fibres like long-stemmed hay. 
• Clinical signs: hair loss around the flanks and body flanks. 
• Diagnosis: broken hairs.

Cheyletiellosis or less commonly Leporacarus gibbus Fur Mite Infection in Lagomorphs (Parasitic Disease)

• Fur mite infections.
• Clinical signs Profuse amounts of large white scale. 
• Distribution of lesions: intrascapular region or around the tail base.
• Diagnosis: Identification of mites under low magnification in acetate tape preparations or skin scrapes. 

Psoroptes cuniculi (Ear Mite) Infection

• Clinical signs: 
  • Beige-brown crusty exudate in the pinna and ear canal.
  • Intense pruritus.
  • Alopecia around the ear base, sometimes extending to the neck, face, abdomen and perineal region.

Flea Infection

• Clinical signs: Patchy alopecia and sometimes a secondary pyoderma.
• Diagnosis: Identification of fleas or flea dirt.

Injection Reactions

• Clinical signs: Alopecia, scale, scabs, and erythema.
• Distribution of lesions: Intrascapular region is the commonest area of subcutaneous injections. 

Ringworm

• Clinical signs: 
  • Not necessarily always ringlike.
  • Partial to complete alopecia with some scaling.
  • May initially start as small papules.

Treponematosis (rabbit syphilis)

• Clinical signs- Alopecia, crusts at mucocutaneous junctions.
• Distribution of lesions- Nose, lips, and genitalia

Sebaceous adenitis

• Clinical signs: Alopecia and copious amounts of white scale
• Distribution of lesions: Often begins around the neck and head.
• Differentiate by: Biopsy and histology.

Cutaneous Neoplasia

• "basal cell tumors, cutaneous lymphoma, cutaneous epithelotropic lymphoma (mycoses fungoides), or mast cell tumors: rare in rabbits".
• Clinical signs: Diffuse or focal truncal alopecia with erythema and scaling and occasionally plaque formation.

Lack of grooming

• Alopecia and accumulation of scale in the tail base area or intrascapular region. 

(B609.2.w2)

Specific Medical Treatment

• Clipping the fur away from the lesion. 
• Cleaning the skin. 
• Application of antibiotic or antiseptic cream. 

(B600.9.w9, B601.13.w13)

NOTE: It is necessary to investigate and treat the underlying cause or predisposing factors of the dermatitis. 

TOPICAL PREPARATIONS

Topical medications should be used with caution as they may be ingested by the rabbit during grooming. (J213.7.w2)

• Antibiotic and/or corticosteroid preparations are often effective. (B600.9.w9)
  • Corticosteroids are easily absorbed from the skin especially if there is inflammation. (B600.9.w9)
  • Prolonged administration of topical corticosteroids may result in skin thinning. (B600.9.w9)
    • Note: great care should be taken when administering corticosteroids to rabbits due to their immunosuppresive and hepatotoxic effects. (V.w128)
  • Fuciderm (Leo Laboratories Ltd.) contains fusidic acid and only needs application once daily. The fusidic acid is effective against Staphylococcus infections that are common in skin pyodermas and it won't interfere with the gut flora. (B600.9.w9)
  • Gentamicin sulfate ointment (B608.21.w21)
  • Topical or injectable Gentamicin may be used to treat Pseudomonas infection. (B615.6.w6)
  • Chloramphenicol ointment applied once daily for ten to fourteen days. (B614.15.w15)
• Zinc oxide plus menthol powder (Gold Bond, Martin Himmel, Inc.) is useful for superficial, moist dermatitis. Apply every 24 hours. (B608.21.w21, B609.2.w2)
• Astringents: aluminium acetate (Domeboro powder, Bayer Inc., Elkhart, IN) (B602.18.w18, B608.21.w21)
  • Apply twice a day. (J213.7.w2)

SYSTEMIC ANTIBIOTICS

• Systemic antibiotics are necessary in severe bacterial dermatitis. (B600.9.w9)
• As a general rule in the treatment of bacterial skin conditions in rabbits, marbofloxacin, Enrofloxacin, or Trimethoprim sulfa are useful for non- suppurative infections and may be given orally. However, purulent infections respond better to the penicillin related compounds. Amoxycillin, Penicillin G, and Cephalexin are safe as long as they are not used orally. These antibiotics must always be administered parenterally. (P601.1.w1)
• The choice of antibiotic should ideally be based on culture and sensitivity especially if the pyoderma is recurrent, resistant or deep. (B600.9.w9, B609.2.w2)
• Antibiotics should be administered for at least two weeks beyond cure. (B609.2.w2) 
• Enrofloxacin
  • Safe in rabbits. (B600.9.w9)
  • 5 - 20 mg/kg orally, or by subcutaneous or intramuscular injection every 12 to 24 hours. (B609.2.w2)
• Trimethoprim combinations
  • Safe in rabbits. (B600.9.w9)
  • Trimethoprim sulfa: 30 mg/kg orally every twelve hours. (B609.2.w2)
• Oxytetracycline
  • Can be used parenterally in the treatment of dermatophilosis. (B609.2.w2)
• For Pseudomonas infections: Enrofloxacin or Gentamicin have the best action. (B606.4.w4)
• Contraindications:
  • Oral antibiotics that select against the Gram-positive bacteria:
    • Penicillins, macrolides, lincosamides and cephalosporins. (B609.2.w2)
    • These may cause a fatal enteric dysbiosis and enterotoxaemia. (B609.2.w2)

ANALGESICS

• NSAIDs e.g. Carprofen, are useful in particularly painful skin infections and also in treating any underlying painful condition that is preventing grooming. (B600.9.w9) 
  • This class of drugs interfere with the synthesis of prostaglandins and have the additional advantage for perineal dermatitis of reducing the production of caecotrophs. (B600.9.w9)  
  • Meloxicam: 0.2 - 0.5 mg/kg orally every 24 hours. (B609.2.w2)
  • Carprofen: 2.2 mg/kg orally every 12 hours. (B609.2.w2)

SEDATION (may be needed for treatment)

• For light sedation: 
  • Midazolam- 0.5 - 2 mg/kg by intramuscular injection. (B609.2.w2)
  • Diazepam- 1-2 mg/kg by intramuscular injection. (B609.2.w2)
• For deep sedation and longer procedures:
  • Ketamine 15 - 20 mg/kg by intramuscular injection and Midazolam 0.5 mg/kg by intramuscular injection. (B609.2.w2)

AVOID: 

• Corticosteroids - topical or systemic
  • May encourage resistance and recurrence even if used concurrently with antibiotics. (B609.2.w2)
  • Topical corticosteroids should be used with caution because they are absorbed and may cause significant adrenocortical and immuno suppression. (J213.7.w2, V.w128)

• Treatment and Care

General Nursing and Surgical Techniques

Removing matted fur

• This is necessary for the treatment to be effective. 
• It is very easy to tear rabbit skin because of its extreme fragility therefore it is necessary to be very cautious when clipping the fur or pulling on mats.
• Electric clippers are usually ineffective in removing thick fur mats; curved scissors are best. Work carefully and slowly so no damage is caused to the skin.
• Use sedation in rabbits with large mats. 

(B609.2.w2)

Bathing

• The overlying fur must be clipped off first or otherwise bathing is counter productive as the dense coat mats easily, dries slowly and the moist conditions are ideal for bacterial growth. (B600.9.w9, B609.2.w2) 
• Remove exudate or faecal contamination. (B600.9.w9)
• Chlorhexidine or povidone/iodine preparations are both suitable skin cleansers. They are also effective against yeasts that can inhabit skin folds. (B600.9.w9, B609.2.w2)
• Use extreme caution when bathing or dipping rabbits due to the high risk of excessive chilling, severe stress, and skeletal fractures. (B609.2.w2)
• Thoroughly dry the animal after bathing. (B609.2.w2)
• See: Bathing Rabbits

Skin protectant-type dressing

• "A polymeric solution of hexamethyldisiloxane acrylate copolymer (No Sting Barrier Film, 3M Health Care, St. Paul, Minnesota) is useful. " (J213.7.w2)

Specific information for treatment of different areas of the body

Moist dermatitis of the dewlap

• Remove the primary source of the irritation, for example, Cheyletiellosis or perineal dermatitis. (B600.9.w9)
• Daily cleansing using an antiseptic solution. (B600.9.w9)
• Surgical removal of skin folds may be necessary. (B600.9.w9, B609.2.w2)

Facial dermatitis

• Keep the affected skin clean and dry. 
• A bonded companion rabbit is useful for licking and cleaning the face. 
• Topical preparations may be useful in controlling the infection but the condition is difficult to cure. 

(B600.9.w9)

Perineal dermatitis

• Clip and clean the perineum under sedation (B600.9.w9)
• The underlying cause must be addressed.
• Provide a high fibre diet to prevent excessive caecotroph production and encourage caecotroph ingestion and also to reduce obesity. (B600.9.w9, B606.4.w4)
• Provide space to exercise and an area to urinate away from the bedding. (B600.9.w9)
• Paraplegic patients require constant nursing to maintain clean dry perineal skin and unmatted fur. (B600.9.w9)
• Surgery
  • remove large folds of skin around the genitalia. (B600.9.w9, B602.19.w19)
  • spay rabbits that have an underlying reproductive disorder that causes vaginal discharge. (B600.9.w9)
• Perineal dermoplasty
  • Providing any other predisposing factors have been identified and treated, this surgery is a simple and effective remedy for chronic dermatitis of the perineum. (B600.9.w9, B609.2.w2)
    • In cases where it is not possible to resolve the underlying cause (as in spondylitis and the accompanying inadequate grooming problem) the removal of the infected skin folds will at least improve the situation. (B600.9.w9)
  • See: Perineal Dermoplasty in Rabbits (Techniques)

Husbandry Changes

Diet

• If obesity is a factor then gradually change the diet to one that is high in fibre and low in starch and fat. (B602.19.w19, V.w128)

Exercise

• Encourage exercise if obesity is a causative factor. (B602.19.w19)

Housing

• Keep rabbits with moist dermatitis indoors because they will be a risk of Myiasis. (J213.7.w2)

• Bathing Rabbits
• Treatment and Care
• Environmental and Population Management
• Preventative Medicine for Mammals

Preventative Measures

--

• Skin areas that are at risk of developing dermatitis (e.g. due to urine scalding) can be protected with zinc oxide and castor oil cream, petroleum jelly, or talcum powder whilst the predisposing cause is being investigated and treated. (B606.4.w4)

• Preventative Medicine for Mammals

Environmental and Population Control Measures

Lagomorphs

• Substitute a sipper bottle for water bowls. (B600.9.w9, B608.21.w21)
  • Although regularly clean these bottles because Pseudomonas aeruginosa is thought to be harboured in them. (B606.4.w4)
  • Prevent progressive dental disease by:
    • selection of rabbits without a genetic predisposition to dental problems.
    • provide a high fibre diet and good quality hay.
    • discontinue or limit the feeding of pellets and vegetables or soft fruits. 
    • Periodically trim the overgrown crowns. 
  • Prevent obesity by allowing the rabbit to exercise and providing a high fibre diet.
  • Provide clean and appropriate surface substrates. 

  (B609.2.w2)

• Environmental and Population Management
• Preventative Medicine for Mammals