WildLife Group of the SAVA
Mycobacterial Arthritis in Painted Reed Frogs ( Hyperolius marmoratus )
M . Barrows *, K . Koeppel †, A . Michel † and E . Mitchell †‡
* Bristol Zoological Society , Clifton , Bristol , UK , † Faculty of Veterinary Science , University of Pretoria , Onderstepoort and ‡ National Zoological Gardens of South Africa , Pretoria , South Africa .
grey – white nodules . Clinical signs vary , with some individuals asymptomatic and others presenting with sudden death , weight loss , anorexia and emaciation , coelomic swelling , bloating and abnormal buoyancy , subcutaneous oedema , ulcerative or nodular dermatitis , ataxia , paralysis and mucopurulent nasal and oral secretions . Pathological tibial fractures , spinal lesions and joint lesions are rarely reported .
Mycobacteriosis is an important infectious disease in amphibians and has been reported as the leading cause of death in some research frog colonies . Mature amphibians are affected more often than tadpoles and mycobacterial infection is often subclinical , with disease developing mainly in immunocompromised animals . Mycobacteria are ubiquitous in soil and aquatic environments and have been isolated from both wild toads and frogs ( anurans ). Mycobacteria can infect anurans through skin lesions or wounds , ingestion , and through protozoan vectors . As in other species , infection results in chronic granulomatous inflammation . Early granulomata can be confused for neoplastic lesions such as lymphoma ; however , the diagnosis can be confirmed by the presence of acid-fast bacilli on histology . In the visceral form , granulomata develop in the liver , spleen , kidneys and gastrointestinal tract . In the cutaneous form , skin lesions include hyperaemia , petechiae and ulcers , as well as miliary
We investigated cases of mycobacterial arthritis and synovitis affecting both the spine and limbs of 20 captive painted reed frogs ( Hyperolius marmoratus ), a small insectivorous anuran species from sub-Saharan Africa . The frogs were collected from the wild in Mpumalanga province , South Africa , for a captive breeding programme designed to help develop husbandry protocols for the critically endangered Pickersgill ’ s reed frog ( Hyperolius pickersgilli ). Affected frogs were found dead or were humanely destroyed due to cachexia , limb paresis , paralysis , deformity or ‘ spindly leg syndrome ’, or because they were in contact with other affected frogs . The first cases occurred in wild caught frogs 14 months after capture . Other cases occurred in captive bred frogs from the F1 and F3 generations .
All of the frogs had multifocal granulomatous synovitis and peri-articular inflammation affecting at least one and often several distal limb , rib or spinal intervertebral joints . Inflammation occasionally extended into adjacent muscle and bones as well as the subcutis ; and rare granulomas were seen in the kidney , liver and meninges . Small granulomata in the spinal canal
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