Dermatology of small mammals and exotic species

• What are the signs of skin disease in exotics?

  Alopecia

  Erythema of the skin.

  Desquamation

  Broken/chewed hairs/ feathers.

  Mass

  Deformed beak/ claws/ shell.

  Pruritus

  Old shed skin

  Hyperkeratosis

  Exudative lesions

  Haematoma/petechiae

  Ulcers/wounds
• Cheyletiella parasitivorax in mammals


  Usually associated with an underlying conditions i.e. something that means they can not clean themselves or correctly, pain in the back legs, overweight. So if see this means that this is not the primary issue, need to look for something else.
• Ferret mast cell tumour

  Ferrets do not have many skin problems, but this is a common one they get. Mast cell tumours are benign in ferrets but they are very itchy, can sometimes find wounds associated with it. Check it as could also be a melanoma.
• trichofolliculoma in a guinea pig


  Most common lump you will find on a guinea pig. Is a benign tumour of the glands of the skin. it is benign but can grow quite big and get ulcerated and infected.
• Mites (Knemidocoptes) - birds


  Birds tend to get problems presenting on areas where there are no feathers. One of the most common problems you will come across in birds.
• Feather cysts in birds

  A feather that did not grow through the skin, can get infected and can get quite big compared to the size of the bird. It is recommended to remove them. Can be hereditary tends to happen in specific breeds of birds, so if this keeps recurring may not be worth GAing it every time.
• Pododermatitis in birds 


  Usually associated with husbandry and benign problems - bird overweight, perch not soft enough, usually associated with the whole bird.
• Reptile skin wounds

  Difficult to solve as the skin is not very elastic and there is a lot of muscle loss, will take a long time to here. When you have a fresh wound like this it is very important to clean it and the skins round it. If a reptile gets an infection it is very hard to treat due to the type of pus they get, and a lot of the bacteria they have is resistant.
• Burns in reptiles

  Quite a common finding due to husbandry issues. Reptiles are draw to heat spots, so if they are systemically unwell they will get closer to a heat producer to raise their body temperature, and when they get to close to the heat source they will burn themselves and they are not able to process the pain of the burn and can get really severe burns. If this happens it is ether because the animal is systemically ill or the enclosure it to cold.
• Dysecdysis in reptiles

  Shedding is a normal thing, if it goes wrong it is caused by dysecdysis, this tends to be a husbandry problem - not enough humidity, nothing to rub on, not warm enough. Fix this by bathing the animal a few times a week, fix the husbandry as well.
• What are the main differentials for skin problems in exotic mammals

  Mites

  Abscess - common in hamsters and ferrets.

  Myasis (fly-strike) - common in rabbits that live outdoors.

  Dermatophytosis - tends to occur in animals that live in overcrowded space or animals that are stressed all the time.

  Mast cell tumour

  Trichofolliculomas
• What are the main differentials for skin problems in birds?

  Mites

  Hypovitaminosis A

  Feather cysts

  Pododermatitis
• What are the main differentials for skin problems in reptiles?

  Traumatic wounds

  Skin burns

  Dysecdysis

  Dermatitis/skin ulcers.
• What is the diagnostic plans for exotics presenting with skin problems?

  Skin cytology/ impression smears

  Acetate tape impression (useful for mites)

  Skin scrapings —-> very careful in birds as the skin is very fragile so do not use a blade as this will just cause more problems.

  Hair, feather or shed skin microscopy:

  • FNA (if there is a mass) (Guinea pigs)
  • Skin biopsy
  • Culture and sensitivity (bacterial fungal)
  • PCR tests (viral disease, PBFD)
• What is the treatment for mites?

  Ivermectin (Xeno), Selamectin, Imidacloprid (Advocate, only ferret).
• What is the treatment for abscesses?

  Surgical usually needed, topical, antibitoics (C&S!!!!! capsule).
• What is the treatment for Myasis (fly-strike)

  Ivermectin (Xeno), Selamectin, surgical debridement, topical treatment.
• What is the treatment for dermatophytosis (ring worm)?

  Topical antifungal (F10), systemic antifungals (side effects) Itraconazole, ketoconazole, terbinafine.
• What is the treatment for mast cell tumours and trichofolliculomas?

  Surgical excision, usually goof prognosis.
• What are the intrinsic causes of feather loss?

  Inappropriate caging.

  Low humidity

  Inappropriate photoperiod

  Circovirus (PBFD)

  Malnutrition

  Mites

  Polyomavirus
• What are the medical causes of feather loss?

  Renal disease

  Septicaemia

  Hepatic disease

  Hypothyroidism

  Allergy

  Dermatitis
• What are the psychogenic causes of feather loss?

  No enrichment

  Lack of exercise

  Inadvertent reinforcement

  Inadequate bond with the owner.

  Hormonal stimulation

  Conflict behaviours.
• What ulcerative disease are in dogs?

  Infectious - Mucocutaneous pyoderma

  Neoplastic - cutaneous epitheliotropic lymphoma

  Immune mediated - vasculitis (rarely cats), Erythema multiforme, SJS and TEN (rarely cats), facial and mucocutaneous DLE

  Traumatic - decubital ulcers
• What ulcerative disease are in cats?

  Viral:

  • Feline herpesvirus infection
  • Feline calicivirus infection
  • Feline cowpox infection

  Immune-mediated/idiopathic

  • Feline plasma cell pododermatitis

  Neoplasitc

  Squamous cell carcinoma
• What is the definition of an ulcers?

  Are full thickness wounds in the epithelium so that the dermis is exposed:

  • Painful - rather than itchy
  • Blood cells and bleeding common
  • Cytologically macrophages likely to be present
• What is the definition of erosions?

  Are shallower wounds in the skin within the epithelium
• What is the definition of crusts?

  Common with both ulcers and erosions. It is sometimes difficult to see the difference without further examination.
• Primary ulceration


  Diseases within the skin that result in epidermal loss.

  Due to:

  • Bacterial
  • Viral
  • Fungal
  • Immune-mediated
  • Traumatic and idiopathic causes.
• Secondary ulceration

  Common.

  Due to:

  • Localised trauma
  • Severe irritation/pruritus
  • Secondary bacterial infections (especially deep pyoderma).
• Ulceration in cats

  If you use steroids in these infections then cause severe illness or even death, so need to be able to recognise these.

  Viral:

  • Feline herpesvirus infection
  • Feline calicivirus infection
  • Feline cowpox infection.

  Immune-mediated/idiopathic:

  • Feline plasma cell pododermatitis

  Neoplastic

  • Squamous cell carcinoma
• Feline herpes virus-1 (FHV-1)

  May not have active or historical URTI signs.

  Usually adults

  Facial lesions make a ‘mask’

  • Eyelids, muzzle and nose
  • +/- elsewhere on body.

  Triggers include stress or glucocorticoids

  Diagnosis on histopathology:

  • Eosinophilic +/- neutrophilic inflammation.

  Important differential = allergic dermatitis (particularly head and neck pruritus and eosinophilic granuloma).
• Calicivirus


  Cutaneous signs rare

  Usually URTI

  • Ulcers and vesicles on mucous membrane, lips and nose.

  A rare presentation involving highly virulent strain (VS-FCV) with severe cutaneous and systemic disease is reported.
• Treatment of URT viruses - supportive care

  Fluids, and nutritional support - feeding (oesophageal) tube.

  Appetite stimulants e.g. mirtazapine

  Steam inhalation may assist de congestion.

  Topical ocular medications are often needed in FHV-1 to treat pain and ulceration

  • Lubricants
  • Antibiotics
• Treatment of URT viruses - specific antivirals


  May be useful in FHV-1:

  • Famociclovir for systemic use in severe cases.
  • Also described for calicivirus.
  • Lysine for FHV-1 is ineffective.
  • Feline interferon omega (by s/c injection or orally for FHV-1, but unknown clinical benefit.

  Antivirals such as trifluidine used for ocular disease FHV-1
• What are the key findings for the diagnosis of cow pox?

  History and clinical signs are consistent:

  • Younger, hunting rural cat.
  • Onset of a single crusted ulcerated lesion.
  • Followed by smaller lesions.

  Possible confusion with:

  • Allergic disease - pruritus
  • Herpes and calicivirus - respiratory disease, ocular discharge
  • Trauma.

  Diagnosis by PCR &/or biopsy
• What are the clinical signs of plasma cell pododermatitis?

  Soft, swollen pads with scaling.

  Ulceration centrally in some.

  Some cats have gingivitis-stomatitis or nasal lesions.

  May be associated with glomerulopathy and/or FIV
• What is the treatment for plasma cell pododermatitis?

  Spontaneous regression.

  Prolapsed material needs surgical repair.

  Immune-modulation:

  • Steroids, ciclosporin
  • Doxycycline commonly used (poor antibiotic stewardship)

  The prognosis is usually good unless there is some underlying disease.
• What are the causes of ulceration in dogs?


  Infectious:

  • Mucocutaneous pyoderma

  Neoplastic:

  • Cutaneous epitheliotropic lymphoma.

  Immune-mediated:

  • Vasculitis (rarely cat)
  • Erythema multiforme, SJS and TEN.
  • Facial and mucocutaneous DLE.

  Traumatic:

  • Decubital ulcers
• Facial discoid lupus erythematosus

  GSD’s/ 7y onset (& many other breeds, but much less common).

  Most common form of lupus.

  Nasal planum/nares.

  Erythemia, depigmentation, scaling -> erosions/ulcerations, loss of architecture of the nasal planum +/- crusting.

  Diagnostic dilemma with mucocutaneous pyoderma.

  HP: subtle interface reaction (cell-rich lymphocytic interface dermatitis) - perform after antibiotics.
• Mucocutaneous lupus erythematosus

  GSD

  Females>males/ 6y onset

  Perimucosal ulcerated skin lesions/ pain on urinating/ defeacating.

  Anus, peri genital region, lips, periocular/symmetrical.

  Diagnostic dilemma with mucocutaneous pyoderma.

  HP: cell-rich lymphocytic interface dermatitis - perform after antibiotics.