In June we received a sorry tale of a little Patterdale terrier, who was found doing what terriers do and mauling an almost-dead and decidedly manky badger. This resulted in wounds to his nose and his eventual death from 'bovine' Tb. ( Please note: the Patterdale in the pic, is for illustration only, and is not the terrier in question. Patterdales are described as 'feisty and fearless' and used for 'hunting vermin'.)
Our terrier's story and that of two other dogs recently positively diagnosed with bTB, is now told by VLA staff and veterinary surgeons attending the animals, and is published in this week's Veterinary Record.
We would like to report on three recent cases of tuberculosis (TB) in dogs caused by Mycobacterium bovis, following bites from wildlife.The paper describes how cultures from affected organs were positive for SBO263 (VLA type 17) which is the predominant molecular type in the area where the terrier lived, and where the badger was found.
The most recent case concerned a healthy seven-year-old pet/working, male entire Patterdale terrier that went rabbit hunting in March 2009 in an area of Worcestershire recognised as a hot spot of bovine TB. The dog went missing and was found chewing the neck of a very thin, moribund badger. The terrier had incurred multiple bite wounds on and around its muzzle during the fight with the badger. The badger carcase was not examined. At the time the private veterinary surgeon alerted the dog's owners to the risk of TB, especially because there was a young child in the household. Antibiotics were prescribed to treat the bite wounds on the terrier's muzzle. After several weeks the dog became listless, weak and started showing respiratory signs and weight loss despite a good appetite. These clinical signs became progressively worse, and on advice from the vet the dog was euthanased in early June. Postmortem examination showed multiple granulomatous lesions in the lungs, pleura, liver, kidneys and lymph nodes.
The second case is that of a Jack Russell terrier, who lived in inner city Glasgow and had a close encounter with a squirrel. This little chap was luckier than the Patterdale, and after treatment, has appeared to recover. The spoligotype isolated in 2008 after a biopsy on a non healing lesion, was Type SBO140 or VLA 9. Scottish VLA staff comment thus, on the strain type and their findings:
This was unexpected because the dog lived in Glasgow, an inner-city area with a very low historical incidence of bovine TB and had no reported contact with any livestock. The dog had reportedly not travelled to an area with endemic bovine TB infection. The skin lesion eventually healed and the dog returned to apparent good health. The third case detailed in Vet. Record occurred in 2007 in Wales, where a three-year-old terrier was suspected of being bitten by a fox or badger while hunting.
He developed nodular, calcified, hugely enlarged submandibular lymph nodes. The bite wounds did not heal despite treatment. The dog was euthanased and M bovis spoligotype SB0140 (VLA type 9b) was isolated from one of the lymph nodes that showed granulomatous lesions with acid-fast bacteria.The authors of the paper indicate that "in all three cases the local Animal Health office and local public health authorities were notified and health and safety advice was given to the dogs' owners". Although in the case of the Patterdale, we understand that this was sketchy and slow, especially as there was a child involved who had had close contact with the dog.
The authors also comment that in all three of these documented cases, there was no known contact with cattle or other livestock. And they mention increasing numbers of cats, dogs, South American camelids and goats as spill-over hosts of 'bovine' TB.
They conclude with an observation about TB in domestic pets in general, and cats in particular :
In cats, many cases of confirmed M bovis infection involve lesions in the skin or superficial lymph nodes, suggesting a cutaneous route of infection. As with these three canine cases, some of the owners of M bovis-infected cats have reported that infection followed a bite by native wildlife.And finally, a plea to their fellow veterinarians, who may be unaware of the extent of environmental' 'bovine' TB pollution to which any mammal is suceptible:
We would like to raise awareness among small animal practitioners to include M bovis infection in the differential diagnosis of bite wounds that are unresponsive to antimicrobial treatment, develop nodular lesions and associated lymphadenopathy and/or cases of general undiagnosed malaise where there is a history of bite wounds. Undiagnosed TB in pets poses a particular zoonotic risk due to the often close contact between these animals and their owners and family.We understand that Defra have approved this article ahead of publication. It is to be hoped that the implications set out in it, are clear to them as well.
The authors of the paper are : G.M van der Burgh,(VLA Luddington, Warwicks.,) T Crawshaw,(VLA Starcross, Devon.) A.P Foster,(VLA Shrewsbury. ) D.J.B. Denny,(B.VET.MED. MRCVS, Worcester.) and A.Shock, (VLA Lasswade,International Research Centre, Midlothian, )