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A four-month-old, 901 gram female scarlet macaw (Ara macao) presented with multiple nodular, variably sized, white-coloured subcutaneous masses on the skin, along the margin of the mandibular beak bilaterally (Figure 1).
There were no abnormalities noted on physical examination and radiographs. The bird presented two months previously due to bacterial folliculitis of the rectrices and generalised illness. The bird is kept indoors in a mixed aviary within a zoological facility. Other birds housed together did not have similar lesions and the keepers did not note any mosquitoes or other insects in the aviary.
Thick caseous chalky white material was expressed from the masses. The exudate was negative for avipoxvirus PCR and showed scant growth of commensal Staphylococci kloosii on aerobic bacterial culture. Modified Wright-Giemsa and Gram stain cytology of a fine needle aspirate showed crystal-like material and a small number of gram-negative rods and gram-positive cocci. The masses did not respond to oral broad-spectrum antibiotic therapy (Clavulanic acid/amoxycillin 125 mg/kg PO BID for 7 days).
One week after initial presentation, five encapsulated masses were surgically removed under general anaesthesia via sharp dissection of the skin. A 1cm wound was left open to allow for drainage of any exudate and flushing of the site post-operatively. The masses were fixed in 10% buffered formalin for histology analysis.
The lesions were composed of multiple variably sized calcified nodules. Each nodule contained mainly mineralised material and was surrounded by macrophages and connective tissue (Figure 2).
Histopathologic diagnosis of the masses was calcinosis cutis. Post-operatively, there was no recurrence of the masses within five months. Broad-spectrum clavulanic acid/amoxycillin PO BID, meloxicam 1 mg/kg PO BID, ciprofloxacin drops and dilute chlorhexidine flush were continued for another week.
The surgical site remained dry, and the skin contracted and healed well. Serum biochemistry and whole blood iStat analysis showed total calcium (2.74 mmol/L), ionised calcium (5.1 mg/dL) and phosphorus levels (1.58 mmol/L) to be within normal limits for this species. There was no recurrence of the skin lesions post-surgical removal.
Calcinosis cutis is a condition in which insoluble calcium phosphate deposits in the cutaneous and subcutaneous tissue2. It can be further described based on cause of the calcium deposition (four processes: dystrophic, iatrogenic, idiopathic, metastatic) and lesion distribution (localised or generalised).
Dystrophic calcinosis cutis results from tissue degeneration or injury with skin necrosis, resulting in the release of proteins which bind to phosphates and cause calcification1. Serum calcium and phosphorus levels are typically normal. No history of trauma to the affected region was noted, but it cannot be completely ruled out. Based on the clinical presentation, localised dystrophic or idiopathic type are most likely.
Acknowledgements
We would like to thank Dr Chia-da Hsu, senior pathologist, Veterinary Healthcare and Scientific Programmes, Mandai Wildlife Group, for the histopathology interpretation and image.
References
1. Doerr KA, Outerbridge CA, White SD, Kass PH, Shiraki R, Lam AT, Affolter VK. Calcinosis cutis in dogs: histopathological and clinical analysis of 46 cases. Veterinary Dermatology. 2013 Jun;24(3):355-e79.
2. Sabater M, Carrasco DC, Huynh M, Homer-Forbes NA, Stidworthy MF. Calcinosis circumscripta in the digital extensor tendon of a tawny eagle (Aquila rapax). Journal of Avian Medicine and Surgery. 2016 Dec;30(4):374-7.
Dr Shangzhe Xie BSc/BVMS, MVS, PhD, DACZM, DABVP (Avian Practice), DACCM,
Vice-president, Veterinary Healthcare and Scientific Programmes, Mandai Wildlife Group
Dr Shangzhe Xie obtained his veterinary degree and masters in conservation medicine at Murdoch University. He then completed a PhD studying the physiology of heat stress in Australian desert birds at the University of Adelaide.
Dr Xie is a Diplomate of the American College of Zoological Medicine in Zoological Companion Animal, American Board of Veterinary Practitioners Avian Practice and Asian Society of Conservation Medicine.
Dr Xie is also on the editorial board of the Australian Veterinary Journal, BMC Veterinary Research, Journal of Avian Medicine & Surgery and Journal of Zoo and Wildlife Medicine.
Dr Serena Shum BSc, BVM&S
Dr Serena Shum obtained her Bachelor of Veterinary Science from the Royal Veterinary College (London) and her degree in Veterinary Medicine and Surgery from the Royal (Dick) School of Veterinary Studies in Edinburgh.
She began her career as an avian veterinary intern at Jurong Bird Park operated under the Mandai Wildlife Group, before transitioning to small animal general practice in Singapore where she continues to work.
Dr Shum is currently pursuing qualification as a Certified Veterinary Anaesthesia Practitioner through the Veterinary Anaesthesia School for Technicians and Veterinarians.
