leishmaniasisfacts

Canine Leishmaniasis Facts

Susana Mendez, DVM PhD
Assistant Professor
Baker Institute for Animal Health College of Veterinary Medicine

Dogs can be infected with L. infantum (in the Old World) or L. chagasi (in the New World). Both are currently considered the same species. Dogs infected with Leishmania develop a spectrum of disease ranging from asymptomatic to oligo- or polysymptomatic dogs.

Canine leishmaniasis is a chronic and slowly progressive disease: in some naturally infected dogs, clinical symptoms do not appear until 1 or 2 years after infection. Symptoms are very variable and include alopecia, local or generalized lymphadenopathy, ocular and periocular lesions, epistaxis (nasal mucosa becomes very dry), emaciation, onychogrypyhosis (abnormal nail growth), diarrhea, emaciation, splenomegaly. Terminal dogs usually present renal failure. Fever may or may not be present.

A small percentage (10%) of the infected dogs appear to be naturally resistant and do not develop the disease. The reasons why these dogs are resistant to the infection are still unclear, although it is well know that resistance to the infection is associated with a strong Th1 type cellular immune response. It has been suggested that certain breeds may be resistant to leishmaniasis, i.e. the Mediterranean Ibizan Hound (Solano-Gallego, 2000), an autochthonous breed from the Balearic Island of Ibiza. Conversely, a high prevalence of leishmaniasis has been found among Foxhounds in North America. The association between dog breeds and susceptibility to leishmaniasis, as well as the factors influencing resistance in dogs are still unclear and need to be carefully studied.

Canine leishmaniasis in the US

Previously considered an exotic disease, canine leishmaniasis has recently been detected within the foxhound population in the United States and parts of Canada. Until recently, visceral leishmaniasis was thought to be primarily an imported disease in North America from regions in southern Europe or South America where L. infantum and L. chagasi are enzootic. However, sporadic cases of leishmaniasis have been reported in foxhounds and dogs of other breeds with no history of travel to areas where leishmaniasis was present, and the origin of these infections remains unknown. In the late summer of 1999, foxhounds at a New York foxhunting club began showing signs of epistaxis, weight loss, muscle atrophy, seizures, alopecia, dermal lesions, swollen limbs and joints, and renal failure. Of the 250 dogs in the kennel, 112 (44.8%) were sick and 29 (11.6%) had died of leishmaniasis the time of the investigation. At that time, autochthonous leishmaniasis had not been reported in dogs, other animals, or humans in New York.

A serosurvey of >12,000 foxhounds and other canids and 185 persons in 35 states and 4 Canadian provinces was performed. Foxhounds infected with Leishmania spp. were found in 18 states and 2 Canadian provinces posing a risk to uninfected dogs and humans.

The infection in North America appears to be widespread in foxhounds and limited to dog-to-dog mechanisms of transmission; however, if the organism becomes adapted for vector transmission by indigenous phlebotomines, the probability of human exposure will be greatly increased.

Until researchers determine how leishmaniasis is transmitted in the United States, the threat to human health is not completely known. Direct transmission would pose a far smaller risk to humans than transmission by insects such as sandflies or ticks. Vector transmission could create a serious public health concern. The disease is potentially fatal in humans, but can be treated.

Sources:
www.cdc.gov/ncidod/EID/vol12no03/pdfs/05-0811.pdf
Gaskin AA, et al. Visceral leishmaniasis in a New York foxhound kennel. J Vet Intern Med. 2002; 16:34–44).

reprinted with kind permission from Susana Mendez, DVM PhD
Assistant Professor: Baker Institute for Animal Health College of Veterinary Medicine
Hungerford Hill Rd. Ithaca, NY 14853
Office: 607 256 5624 Lab: 607 256 5617 Fax 607 256 5608
www.susanamendez.com

The above information is simply informational. It's intent is not to replace the advice of a veterinarian nor to assist you in making a diagnosis of your pet. Please consult with your own veterinarian for confirmation of any diagnosis. Your pets life may depend on it.