bonecysts

Bone Cysts in the Dog

Bone cysts are rare in dogs. They may involve one bone (monostotic) or multiple bones (polyostotic). They are fluid-filled swellings of the bone and generally benign in nature, although if they weaken the structure of the bone they may predispose to pathologic fractures. The cause of bone cysts is unknown. Single cysts are lined with connective tissue when examined microscopically and usually are presented in young dogs ranging from 4.5 months to 2.5 years. Multiple cysts are more complex consisting of an inner lining membrane with an eosinophilic layer and a layer of nucleated cells surrounded by oedema and vascular tissue and have been reported to have developed in dogs less than 1 year of age.

Bone cysts may cause no signs, but an owner my notice swelling of the leg in the region of the cyst. Large cysts can cause lameness particularly if the cyst forms near a joint. Thin walled cysts can fracture causing sudden onset lameness and pain.

A biopsy is required to differentiate them from bone tumours. Xrays confirm the diagnosis. Cysts appear as black radiolucent swellings in the metaphysis of the long bones (most often the ulna or radius in the foreleg). There is thinning of the walls (cortices) of the bone and in some cases fracture of the wall, leading to an increase in density in the cavity due to haemorrhage. Small cysts do not require treatment, but symptomatic or large cysts may be curetted and packed with a cancellous bone graft to encourage healing

Breeds Most Affected
Monostotic Bone Cysts	Polyostotic Bone Cysts
Afghan Hound Doberman Pinscher German Shepherd Dog Great Dane Irish Wolfhound Saluki Weimaraner	The Doberman Pinscher Golden Retriever Mastiff-crosses
	(This condition is thought to be an hereditary disorder in Doberman Pinschers.)

Textbook of Veterinary Medical Nursing By Carole Bowden, Carole Martin, Jo Masters

Bone Cysts in the Dog