Visceral leishmaniasis does not develop in all infected animals. In fact, in the same ongoing study, about half of the infected
individuals did not exhibit clinical signs, which typically include depression, loss of condition, muscle wasting, a dull
coat, mild abdominal distention, serosanguineous nasal discharge, splenomegaly, generalized lymphadenopathy, and fever.
Clinical findings of the disease can include
- A decreased hematocrit
- Signs of renal failure, including azotemia, hyperphosphatemia, and hypermagnesemia
- Signs of hepatic compromise, including elevated alkaline phosphatase activity, elevated alanine transferase activity, and
- Hyperproteinemia in the form of hyperglobulinemia with hypoalbuminemia
- And proteinuria—glomerular nephritis is the leading cause of death in untreated dogs.
Diagnosis remains difficult in both people and dogs since infected individuals can remain seronegative for years. People can
be screened through the CDC by indirect fluorescent antibody assay. But this test can cross react with Trypanosoma cruzi, the infective agent of Chagas disease. In the United States, an ELISA test and a K39-antigen assay are available for diagnosing
canine leishmaniasis. However, the use of qualitative polymerase chain reaction assays appears to be the best predictor of
Treatment of canine leishmaniasis is not considered curative, and the prognosis for severely affected animals is poor. Owners
should be informed that the organism is never completely removed and that it has zoonotic potential, especially if there are
immunocompromised individuals in the household. Relapses are common and require ongoing treatment. In the United States, infected
dogs without evidence of renal insufficiency are maintained on allopurinol. This treatment, along with a high-quality diet
to reduce the wasting, results in an 80% survival rate. Other medical treatment options exist, but they do not appear to provide
additional benefit, and several are not licensed for use in the United States. Brazil is the first country to license a vaccine
for use in dogs, and sand fly vector control efforts including permethrin and deltamethrin collars have helped to prevent
disease in endemic areas.
Thus, in North America, canine leishmaniasis appears to only be endemic in foxhounds at this time, but finding a genetic link
will require further investigation. Likewise, while sand flies are not confirmed vectors here, they are likely to play a role
in transmission as this agent proliferates.
Source: Petersen CA, Barr SC. Canine leishmaniasis in North America: emerging or newly recognized? Vet Clin North Am Small Anim Pract 2009;39(6):1065-1074.