Feline leishmaniosis: Is the cat a small dog?

Leishmania infantum is a vector-borne zoonotic disease transmitted by phlebotomine sand flies and dogs are considered the main reservoir of the parasite. Feline leishmaniosis (FeL) caused by L. infantum is an emergent feline disease more and more frequently reported in endemic areas. This review summarizes current knowledge focusing similarities and differences with canine leishmaniosis (CanL). Cats are infected by the same Leishmania species than dogs but prevalence of the infection is lower and cases of disease are less frequently reported. Scarce information is available on adaptive immune response of cats naturally exposed to L. infantum infection and mechanisms responsible for susceptibility or resistance of feline hosts. However, about half of clinical cases of FeL are reported in cats with possible impaired immunocompetence. Coinfections or comorbidities are frequently detected in sick cats and they can contribute to a misrepresentation of clinical FeL albeit lesions associated with the presence of the parasite have been detected in skin, lymph nodes, spleen, bone marrow, liver, oral mucosa, stomach, large bowel, kidney, nasal exudate, lung, eye. As for dogs, skin or mucocutaneous lesions are the most common reason for veterinary consultation and finding on physical examination in cats with leishmaniosis. Molecular investigations of Leishmania DNA and anti- Leishmania antibody detection are largely used with the same methodologies for both CanL and FeL, however few information is available about their diagnostic performance in feline hosts. Treatment of cats with clinical FeL is still empirically based and off label by using the most common drugs prescribed to dogs. Life expectancy of cats with clinical FeL is usually good unless concurrent conditions or complications occur and prognosis does not seem significantly influenced by therapy or retroviral coinfection. According to current knowledge, cats can play a role as additional reservoir host of L. infantum and, in a « One Health » perspective, preventative measures should be taken. In conclusion, albeit feline infection and the associated cat disease caused by L. infantum is increasingly reported in endemic areas and have many similarities with CanL, consolidated evidence-based knowledge is not available and we cannot exclude that important differences between dogs and cats exist about transmission, immunopathogenesis and best practice for management and prevention.