Exotics dermatology Flashcards
Describe the appearance of normal moulting in rabbits
- Usually twice a year
- Large areas of fur loss
- New fur often different shade or colour
- Rule out disease by demonstrating new hair growth with no scurf or parasites
Explain how moulting in rabbits can lead to disease
Rabbits ingest a lot of the moulted fur which can lead to GI obstruction in some cases
List common sites for dermatitis in rabbits and give the common causes
- Face: epiphora due to dental disease
- Dewlap: obesity, dental disease, water bowls
- Medial forelimbs: epiphora, nasal discharge
- Perineum: urine scald, caecotroph build up, excessive skin folds, obesity, dental disease, DJD
- Hocks: rex, obesity, poor hygiene, stress
Why are rex rabbits more prone to hock dermatitis?
Reduced guard hairs on feet
What are the common causes of otitis externa in rabbits?
- Lop ears
- Hindlimb disease/amputation
- Psoroptes cuniculi
Explain why lop ears can cause otitis externa
Deformed ear canal preventing wax coming out of the ear
What are thick crusts on the ear of a rabbit with severe pain pathognomic for?
Psoroptes cuniculi
Outline the treatment of Psoroptes cuniculi
- Do not remove debris, too painful
- Ivermectin, selamectin very effective
- NB: Live up to 21 days off host
Name the flea of rabbits that commonly affect the
a: ear
b: dorsum and rump
A: Spiopsyllus cuniculi
B: Ctenocephalides canis and felis
What is the importance of rabbit fleas?
Important vectors of myxomatosis and viral haemorrhagic disease
Describe the treatment of flea infestation in rabbits
- Imidacloprid (Advantage) licensed
- Selamectin and ivermectin effective, but not licensed
- Fipronil causes fatalities
Name the mites that commonly affect rabbits
- Leporacus gibbus (surface)
- Cheyletiella parasitivorax (surface)
- Demodex cuniculi (deep)
- Sarcoptes scabiei (surface)
- Trombicula autumnalis (surface)
Describe the appearance and clinical signs of Leporacus gibbus in rabbits
- Live on hair shafts, just visible to naked eye as salt and pepper appearance
- Usually asymptomatic but can cause pruritus
Describe the common appearance of Cheyletiella in rabbits
- Usually between shoulders and along dorsum
- Large amounts of scurf
- Often causes pruritus
What are 2 important considerations when dealing with a rabbit infested with Cheyletiella?
- Zoonotic
- Can live off host for 10 days
Describe the appearance and prevalence of Sarcoptes scabiei in rabbits
- Pruritic lesions on face, neck and genitalia
- Very rare in UK
Describe the clinical signs of Demodex cuniculi in the rabbit
Usually asymptomatic
Describe the clinical signs and importance of Trombicula autumnalis in the rabbit
- Predilection for ears, feet, perineum
- May cause hypersensitivity reactions
- May be vector for myxomatosis
Describe the importance of Haemodipsus ventricosus in rabbits
- Sucking louse
- More common in unhygienic conditions
- May be a vector for myxomatosis
Explain the cause of myiasis in rabbits
- Poor husbandry or other underlying reason
- Flies attracted to wounds, faeces, urine and discharges
- Maggots cause extensive tissue destruction and eat live tissue
How can myiasis in rabbits be prevented?
- Daily monitoring in healthy rabbits usually enough
- Can use preventative treatment such as pyrethroids, cyromazine (RearGuard) or permethrin (Xenex Ultra spot on)
- Address underlying cause
Outline the treatment of myiasis in rabbits
- Fluid therapy
- Analgesia
- Antibiotics
- Prokinetics
- Clipping and cleansing wound
What agent causes rabbit syphilis?
Treponema cuniculi (spirochete)
How is rabbit syphilis spread?
Copulation and close contact e.g. communal water bowls
Describe the appearance of rabbit syphilis
Crusting lesions of mucocutaneous junction of nose, lips, eyelids, genitalia and anus
Outline the diagnosis of rabbit syphilis
- Test often gives false negatives
- Lesions are suggestive
- Serology, cytology and histopathology
- Silver staining techniques required
- Response to treatment with penicillin
Describe dermatophytosis in rabbits (pathogens, lesions, treatment)
- T. mentagrophytes and M canis
- Zoonosis
- Young more susceptible
- Lesions often confined to pinna and feet
- Topical miconazole or clotrimazole or oral itraconazole usually effective
Describe papillomas in rabbits (location and treatment)
- Rectoanal junction and oral mucosa
- May resolve spontaneously
- Surgery if causing problems
List the cutaneous neoplasias that are common in rabbits
- Fibrosarcoma
- Basal cell carcinoma
- Squamous cell carcinoma
- Lymphoma
- Mammary gland adenocarcinoma
- uterine adenocarcinoma
- Osteosarcoma
Outline the diagnosis of neoplasia in rabbits
- Cytology
- Biopsy
- Screen for metastasis
How is myxomatosis spread?
- Insect vectors
- Direct contact
- Inhalation
Describe the clinical signs of typical myxomatosis
- Oedematous thickened eyelids, lips, ears, perineum, genitalia
- Death
- Early signs can resemble acute pasteurellosis, but oedema of perineum is pathognomic
How may cutaneous myxomatosis occur?
If rabbit has some immunity to the virus, often recover from this form
Describe the clinical signs and prognosis of cutaneous (atypical) myxomatosis
- Scabs around ear, nose, mouth
- Treatable, euthanasia not usually required
List the common dermatological diseases of guinea pigs
- Hypovitaminosis C
- Alopecia
- Chewing lice
- Scent gland disease
- Cervical lymphadenitis
- Cheilitis
- Pododermatitis
- Trichofollliculoma
Describe the signs and importance of hypovitaminosis C in guinea pigs
- Alopecia, gingivitis, swollen painful joints
- May predispose to other skin ndiseases
List potential causes of alopecia in guinea pigs
- Gestation/lactation
- Cystic ovary
- Mites
- Dermatophytosis
Describe the occurrence cystic ovaries in guinea pigs
- Common in sows >18mo
- Often incidental finding
Describe the clinical signs of cystic ovaries in guinea pigs
- Bilateral symmetrical alopecia if increases hormones
- Abdominal discomfort, gut stasis, anorexia
How are cystic ovaries in guinea pigs diagnosed?
Usually palpation, can use ultrasound if unsure
Outline the treatment of cystic ovaries in guinea pigs
- Prolonged disease progression, risk of death under anaesthesia if too far along
- Ovariohysterectomy teatment of choice
- Percutaneous drainage followed by hCG or GnRh may give some relief if surgery is not an option
Describe the clinical signs of trixicarus caviae in guinea pigs
Intense pruritus that may result in seizures when handled
Name the chewing lice of guinea pigs
- Gliricola porcelli
- Gyropus ovalis
What diseases of the scent glands are common in guinea pigs?
Infection, neoplasia, hyperplasia
What is the agent that causes cervical lymphadenitis in guinea pigs?
Streptococcus zooepidemicus
What causes cheilitis in guinea pigs?
Pox virus, acidic or abrasive food
What causes pododermatitis in guinea pigs?
Poor husbandry, old age, underlying disease, foot pad hyperkeratosis, overgrown claws
What is a trichofolliculoma?
A common benign neoplasm that may grow very large if left untreated
List the differential diagnoses for rabbit syphilis
- Atypical myxomatosis
- Neoplasia
- Trauma
- Pyoderma
What is the main cause of skin disease in captive reptiles?
Deficiencies in husbandry
- Most common: hypovitaminosis A, incorrect humidity, inappropriate temperature
What is dysecdysis?
Poor shedding of skin
Which reptiles shed skin as a whole piece, and which shed skin piecemeal?
- Snakes and some lizards (e.g.. geckos) shed whole skin
- Chelonia and some lizards (e.g. bearded dragons) shed piecemeal
- Tortoise only shed skin on head and legs
- Terrapins shed skin over shell
Why might loss of digits and tail tips occur with dysecdysis?
Formation of constricting bands causing ischaemic necrosis
How may blindness occur as a result of dysecdysis?
Failure to shed spectacle in species that have these
How may rostral abrasions occur as a result of dysecdysis?
If snakes lack rough surface on which to initiate ecdysis will rub excessively to open skin, leading to excoriations
What may cause frequent ecdysis?
- Very species specific
- Skin parasites
- Rarely hyperthyroidism in some lizards
- In other lizards and snakes is due to hypothyroidism
- In some can be either
Outline the treatment of retained spectacles in snakes
- Moisturise and emollient over period of weeks
- Very gentle rubbing, no pulling as will remove normal spectacle
Compare the production of vitamin A in reptile species
- Some need preformed vit A (e.g. Chameleons)
- Others need beta-carotene to cleave themselves
Describe the presentation of hypovitaminosis A in lizards
- Blepharospasm due to collection of sub-palpebral debris
- Impacted hemipenes
Describe the presentation of hypovitaminosis A in terrapins and give an important differential
- Palpebral oedema
- Hyperkeratosis
- Ear abscesses
- Differential: Pseudomonas
What pathogens are common causes of bacterial infections in reptiles?
- Often Gram -ve rods
- e.g. Klebsiella, E. coli, Psuedomonas spp
Describe the clinical signs of bacterial infection in reptiles
- Septic blush (hyperaemia and capillary damage)
- Cutaneous vesicles
- Abscesses
- May extend to bone resulting in osteomyelitis
Compare pus in reptiles to that of mammals
In reptiles, is usually solid and required excision
What is SCUD and describe how this may present
- Septicaemic cutaneous ulcerative disease in aquatic chelonia
- Discolouration and lifting of scutes on shell
What is the primary dermatomycosis of reptiles?
Chrysosporium anamorph of Nannizziopsis vriessii (CANV)
Describe fungal infections of reptiles
- Often opportunistic and secondary to poor husbandry and immune compromise
- Include Aspergillus, Fusarium, Microsporum, Candida and Saprolegnia
Describe CANV of reptiles, including disease process and treatment
- Aka “yellow fungus disease” due to gross appearance of some lesions in bearded dragons
- Contagious, may spread to major organs resulting in death
- Itraconazole effective in some cases
Describe the lesions of CANV in Green Anacondas
Small, off-white and vesicular
Outline the importance of parasites in reptiles
- Wild caught may harbour ticks, mites, nematods, cestodes and pentastomids
- Captive bred tend to suffer from fewer skin parasites
- Implicated in spread of some viral diseases such as IBD
Give an example of a skin parasite of snakes and some lizards
Ophionyssus natricus
