Etiologies (causes) of Avian Inflammatory Skin Disease
Presenting Author: Drury Reavill, DVM, Dipl ABVP (Avian)
Pathologist for Zoo/Exotic Pathology Service, West Sacramento,
Interpretive Review and comments by Dr. Nemetz:
Tail Trauma is an actual tear of the skin and muscle from their attachments on the ventral tail base just caudal to the vent. This is seen mostly in young cockatiels, (Click here to download The BIRD C News "Cockatiel Concerns and Syndromes") but has been seen in conures, cockatoos, and African grey parrots. Young birds need to be carefully evaluated before their wings are clipped because an inappropriate clipping is a common precursor to this injury. (Click here to download The BIRD C News "Recommended Safe Method for Wing Clipping")
Mites ( Knemidokoptic mutans and K. pilae) are most commonly found on budgerigars and canaries, but have been reported in Gouldian finches, cockatiels, amazon parrots, ring-neck parakeets, scarlet-chested parrots, princess parrots, mynahs, and yellow-fronted kakariki.
Lesions are found on the unfeathered skin around the beak, cere, vent, legs and feet. Transmission is directly from bird to bird but birds can be asymptomatic carriers for long periods of time (years). Early diagnosis is important to prevent permanent skin damage. Modern drug therapies are usually very effective but the bird should be further evaluated with blood testing, as severe cases usually indicate poor diet, husbandry, or immune system deficiencies.
Red mites (Dermanyssid mite) are external parasites most commonly reported on canaries but Dr. Nemetz has seen them on several species if exposed to infected wild birds. The mite feeds at night and spends the day off the bird. These mites have been reported to live in excess of 30 weeks in the environment after only one blood meal. These mites also will attack humans. Environmental control is important to permanently curing the infestation in the bird.
Myialges nudus mite is a mange mite causing a pruritic (itching) condition usually on the head in grey-cheeked parakeets more than other species. It has been described in an Amazon. It requires a transport host to carry the eggs to a new host. Now that importation has ceased this is a very rare condition in avian medicine.
Quill mites have been described in passerines and psittacine birds. The feathers appear abnormal with thickened, easily split shafts. Diagnosis requires microscopic examination of the abnormal feathers or on skin/feather biopsies.
Lice are divided into two categories: biting and sucking. Avian species only have biting lice and are host specific (They only feed on birds but can be found temporarily on other animals). Symptoms are mild to often asymptomatic. Dr. Nemetz has diagnosed these mostly in cockatiels and grey-cheeked parakeets as well as pigeons and chickens.
Mycotic (fungal) Diseases
Luckily mycotic skin diseases are not common in pet birds. The finding of a fungal organism on the skin is not in itself considered a disease as this is often found in healthy birds. One must have a skin disease condition with an invading fungal organism to confirm a mycotic dermatitis.
There have been numerous fungal organisms attributed with skin disease. The most notable are Aspergillus species, Penicillium species, and Candida species.
Beak fungal infections are usually of a slow chronic nature, involving the nasal sinuses and are often difficult to treat. These infections can cause extensive damage to the sinus and beak. Most often there is some underlying condition such as cancer or a poor immune system therefore a thorough diagnostic evaluation is recommended including a biopsy of the lesion. Since treatment protocols are often long and expensive a proper diagnosis is the best chance for a resolution to these difficult chronic problems.
Candida species is seen most often at the commissures of the mouth, around the nares, and sometimes in the feather follicles. Again these infections are often secondary to some other primary disease process. Cultures and biopsies are recommended along with a systemic evaluation of the bird's condition.
Dermatophytes such as Microsporum gypseum have been reported in psittacines but generally are rare conditions in pet birds. Lesions are often seen as scaly skin and patchy feather loss around the head, neck or breast.
A rather new yeast organism Malassezia slooffiae has been found to cause thickening and flaking of the skin with variable feather loss in psittacine and passerine (canary) species.
Bacterial diseases of the skin can be primary or secondary. The most common bacteria associated with folliculitis are Staphylococcus species. E. coli and Nocardia species have also been found in dermal abscesses. Generalized bacterial dermatitis (pyoderma) tends to be pruritic and can lead to self-trauma and more severe lesions. The most common isolate is Staphylococcus aureus, as these develop from existing bacterial flora of the skin. Pseudomonas sp. infections occur as well with a more severe condition including cellulitis. These are seen most in cockatiels, eclectus parrots, and African grey parrots.
Mycobacterium infections (avian tuberculosis) have been reported mainly on the head secondary to systemic disease. There is potential of human disease and must be handled carefully. Long term treatment is required as well as proper client counseling. Some veterinarians will not treat this disease due to its potential contagiousness to humans. Dr. Nemetz has diagnosed avian tuberculosis lesions on the side of the face, the middle ear, and areas extending from the cervical air sac. Surgical debridement and systemic long term therapy has produced excellent results with some patients still alive and clinically normal 12 years after initial diagnosis.
Papillomavirus is a disease of the unfeathered skin of the face and feet. It has been seen in African grey parrots, some finches, and canaries.
Polyomavirus (Budgerigar Fledgling Disease) can infect ALL psittacine birds but the skin form is seen most often in budgerigars. This disease is often deadly. There has been diagnostic testing available since 1994 and a vaccine since 1996 to help guard against infection. Boarding one's pet is the biggest risk to acquiring this or any other airborne disease agent.
Poxvirus is a species specific disease of the oral cavity or skin around the head and feet. It is mostly seen in lovebirds, amazons (less often in amazons since the demise of importation) as well as sparrows. In the wet form where the virus invades the mucous membranes of the mouth there is a high mortality. In the dry form, if the bird survives, it will leave scars where the lesions began.
Circovirus (Psittacine Beak and Feather Disease, PBFD) is most frequently seen in old world birds such as lovebirds, budgerigars, lories, lorikeets, cockatoos, eclectus parrots and African grey parrots but has been diagnosed in most species of psittacines. Some birds show various feather abnormalities while others demonstrate non-specific signs of an ill patient. Infected lovebirds often will show no signs of disease at all. There has been diagnostic testing available since 1994 to help identify infected individual birds and protect against viral spread. Again, boarding in an unsecured environment is the biggest risk to acquiring this airborne viral disease. There is no cure for this disease and there is no vaccine at the present time to protect non-infected birds.
Diseases of the Feet and Legs
Amazon foot skin necrosis is a syndrome with automutilation seen primarily in yellow-naped amazon parrots but is also seen in cockatoo species. Birds act very pruritic and will aggressively attack the affected area. No specific cause has been identified and the behavior tends to be cyclic. In the control of this syndrome, extensive evaluation of the bird's overall health is important along with the evaluation of the bird's environment and behavior (sexual and non sexual).
Cutaneous herpes lesions can resemble dermal papillomas. They are most commonly found on the feet and toes in macaws and cockatoos. Mode of transmission is not known but is assumed to be by direct contact and appears to be not highly contagious. Treatment that has helped includes anti-herpes creams and peripheral surgical removal of the growth.
Gout is the formation of uric acid crystals most commonly over the joint of the feet and wings. It is most commonly seen in budgerigars and cockatiels. It is usually very painful with lameness as the most common presenting complaint. Therapy is directed at discovering and treating the underlying condition to minimize the progression of the process. Surgical removal or exploration is NOT recommended because it is not possible to remove all the deposits and there is usually profuse bleeding involved.
Pododermatitis (inflammation of the skin of the foot) most often is seen secondary to trauma. Staphylococcus aureus is the most common bacteria isolated from these lesions. Improper perch size and texture is a common cause of lesions to the bottom of the feet of parrots. Perches that are too large will force weight bearing to occur on the hocks and predispose the bird to this condition. When you purchase a perch for your pet bird please get proper counseling in its selection and even let your pet "trial" the perch before making a final decision. At The BIRD Clinic we offer this free service to our clients in the perches we offer for sale.
Diseases of the Uropygial Gland
This is often presented as an enlarged gland located at the dorsal (top) part at the base of the tail. Sometimes it may present as bleeding in that area that may be confused with a broken blood feather. Vitamin A deficiency can predispose a bird to this condition by causing the occlusion of the ducts exiting the gland. Bacterial and fungal infections have been demonstrated which can lead to extensive inflammation if not treated aggressively.