Tuberculosis in young, raw-fed cats in the UK

CASES of feline tuberculosis (TB) havebeen recently identified in 11 catsacross Scotland and England.All had similar clinical signsand highly indicative diagnostics,including granulomatousinflammation with acid-fastorganisms of typical mycobacterialmorphology; 10 tested positive byMycobacterium tuberculosis complex(MTBC) PCR, initially performed byLeeds University Teaching Hospitalreference laboratory. The APHAundertook additional testing wheresamples were available; five caseswere officially confirmed by thereference test of mycobacterialculture and whole genomesequencing (WGS) (Table 1).This cluster is unusual asMycobacterium caprae (akaMycobacterium bovis subspeciescaprae) was identified in six casesthat could be speciated beyond theMTBC. M caprae is considered exoticto the UK and rarely identified in UKcattle, deer or wildlife.1 Phylogeneticanalysis of the APHA WGS resultsidentified all of the M caprae isolatesto be closely related, consistent witha common source of infection.Affected cats were young (eightwere under two years old) and mainlypedigree with either none, or limitedand controlled outdoor access. Nonehad access to raw milk since adoptionas kittens or been exposed to peoplewith active TB. All were fed at least inpart, the same raw food diet.While TB in cats is most commonlyseen as a cutaneous diseaseassociated with hunting rodents,2these new cases had mainlyrespiratory signs, highly similar tothose seen in previous raw food-associated cases.3 Respiratory signswere present in 10 of the new cases,eight had concurrent intra-abdominaldisease. Eight of nine cats available tofollow-up were euthanased on welfaregrounds following rapid deterioration.Currently, to our knowledge, only onecat is responding well to therapy.Critically, five cats hadbronchioalveolar lavage (BAL)performed during their diagnosticinvestigations; two of the BAL sampleswere tested by Ziehl-Neelsen stainingand both were positive for acid-fastbacteria. These cats may have beenactively expectorating infectiousorganisms with known zoonoticpotential.