Evidence for amphibian CRGV link gathers pace

A fish vet believes she may have taken a step towards solving the mystery cause of cutaneous and renal glomerular vasculopathy (CRGV) in dogs, and is appealing to the profession to help further her research.
Fiona Macdonald began looking into the possibility that the bacterial pathogen Aeromonas hydrophila might be involved in the aetiology of CRGV, also referred to as Alabama rot, three years ago.
This bacterium is present in watercourses and soil, and is commonly associated with diseases of fish and amphibians. It is known to cause distinctive ulcerative skin lesions in fish, with subsequent kidney failure.

Serology test

Dr Macdonald, who receives funding from the New Forest Dog Owners Group, developed a serology test with Biobest Laboratories to look at the possibility of antibodies to A hydrophila.
Samples were obtained from veterinary practices around the country – from Aberdeenshire to the south-west of England – mainly from both suspected and confirmed cases of CRGV, as well as in-contact dogs.
Dr Macdonald expressed her surprise at the number of dogs showing antibody response to the organism.
The investigation of possible infectious causes of CRGV has also led to what Dr Macdonald describes as “a real light-bulb moment”, with a suspected link to the UK amphibian disease red-leg syndrome.

Further investigation

Red-leg syndrome is a widespread, contagious infection seen in frogs, toads and newts, and causes redness of the skin and open sores, ultimately resulting in death in a high number of cases. A hydrophila is one of the organisms understood to be involved in the syndrome, and initial research appears to suggest a similar UK geographical spread pattern for both red-leg syndrome and CRGV.
Dr Macdonald observed: “Although A hydrophila is implicated in a major disease problem in amphibians – red-leg syndrome – this is associated with a Ranavirus. There is some evidence the Ranavirus may be the primary pathogen, with the A hydrophila as an opportunist.”
Dr Macdonald freely accepted no conclusive evidence had been established, but insisted the volume of circumstantial evidence was growing apace and warranted further investigation. To that end, she appealed for more samples to further her research.