Continued from page 1Medical Problems or Differences from Typical Disease Manifestations
Constricted Toe Syndrome Constricted toe syndrome has been recognized for years by Eclectus breeders, but has been only sporadically commented on in the veterinary literature. This problem is also recognized in several other psittacine species, and a similar syndrome has been reported in the human pediatric medical literature.
In human medicine, the lesion is described as an annual constricting band(4). In man, the incidence is estimated to be one in 5,000 to 10,000 live births, and the specific etiology is unknown. The preferred treatment is surgical, with a staged Z plasty recommended to release the constricting band prior to permanent neurologic and vascular compromise.
The clinical appearance of constricted toe syndrome in parrot species is that of a constrictive lesion around one or more toes, giving the appearance that a fiber or string may be the cause. The location of the site on the toe that is involved and the number of digits or feet affected is variable.
This syndrome is recognized uniquely as a pediatric problem only. The ages of affected birds will range from only a few weeks old to several months of age. Once a chick is fully weaned, development of constricted toe syndrome has not been documented. The incidence of constricted toe syndrome has been commented on by many aviculturalists as being more prevalent in the last hatched chick of a clutch, and is usually seen in the first digit. Multiple digits and multiple chicks from the same clutch are not uncommonly encountered, however. Although most frequently seen in chicks being hand fed, constricted toe syndrome is seen in chicks in the nest as well, and may be noticed by the aviculturalists at the time chicks are pulled from the nest for hand-rearing.
When seen in Eclectus chicks, the incidence is somewhat sporadic. Some individual pairs of birds have a much higher frequency of problems than others.
The cause of this syndrome remains poorly understood. Histopathology of numerous specimens reveals nothing more than a fibrous band of connective tissue literally impinging on the blood supply to and from the distal aspects of the digit. Suggested factors that may predispose a chick to constricted toe syndrome have included inadequate brooder humidity, suspected but undefined nutritional etiologies, bacterial infection or hypersensitivity reactions, fungal toxins and genetic predisposition.
Popular treatments for the syndrome include massage with warm water baths, magnesium sulfate soaks and topical DMSO. Some veterinarians recommend antibiotic therapy routinely, while others (this author included) do not.
A preferred surgical treatment has been described and is recommended. In most chicks, general anesthesia is not needed. The foot is prepared using routine surgical preparation technique, and preferrably two longitudinal incisions are made perpendicularly through the full thickness of the skin on both sides of the digit. A rapid release of retained blood from the distal segment is indicative of a good prognosis for saving it from avascular necrosis. The digit is routinely bandaged, and this bandage is removed in approximately three days. Regular massage of the toe is helpful in increasing blood supply if there is concern about inadequate circulation. Amputation is indicated if the toe has been deemed lost or is posing a threat to the chick's health or physical comfort.
Hypovitaminosis A
It has been generally acknowledged through the years among Eclectus aviculturalists that these birds tend to have a higher frequency of problems related to vitamin A deficiency even when fed a diet that may seem quite adequate for other psittacine bird species. These observations are testimonials alone, and are based on observation and response to vitamin A treatment. It is hypothesized that hypovitaminosis A is a contributory role in the short life expectancy and dull personalities noted in past references(8,9).
The suggestive signs may not always be as is classically reported for vitamin A deficiency. Dull feather coat, elongated upper beaks, a loss of normal orangish - yellow color of the rhinotheca and infertility may be observed. These signs are not diagnostic for vitamin A deficiency, but should be considered to be additional suggestive signs when noted. The more classically encountered signs of vitamin A deficiency include squamous metaplasia of the salivary glands, caseous lesions of the choana, metaplastic changes of the syrinx, obstructive renal disease, reduced egg produduction, egg binding, poorly formed egg shells, decreased sperm motility, and hyperkeratosis of the metatarsal and digital pads(7).
Although numerous suspect cases with these signs have responded favorably to vitamin injections or supplementation, a direct correlation to true vitamin A deficiency is infrequently made in the Eclectus parrot. More advanced signs and lesions supportive of hypovitaminosis A are reported in Eclectus parrots as well as other psittacine bird species, however correlation with true dietary vitamin A levels is uncommon.
Many veterinarians treat suspect deficient birds with a single combined injectable vitamin A and D3 product, and change the diet more appropriately. The dietary recommendations generally are to emphasize fresh foods as the predominate component of the diet, add in some pelletized commercial product, and offer a small and limited amount of seed mix daily. Regular vitamin supplementation over and above this feeding program is no longer recommended.
The incidence of vitamin A deficiency related problems is uncommon with experienced Eclectus aviculturalists. This observation supports the belief that if the primary diet is appropriate, the clinical or subclinical problem should not be seen.
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