Frequently asked questions about canine leishmaniasis
1. What is canine leishmaniasis (pronounced ‘leesh-man-i-asis)?
- It is a severe, often fatal, disease of dogs caused by a microscopic parasite called Leishmania infantum. The parasite was named in honour of Lt Gen. Sir William Leishman, a Scottish Army doctor.
2. How does a dog catch leishmaniasis?
- Almost always dogs get infected by the bite of a tiny blood-sucking insect called a sand fly. Female sand flies suck blood for protein to make their eggs. If a fly bites an infected dog, the Leishmania parasite grows in the stomach of the fly and, later, when the fly bites again, infective forms of the parasite are injected into the skin of the animal which may then develop leishmaniasis.
Very rarely, a healthy dog can get infected by being in close contact with a dog with leishmaniasis, or puppies of an infected bitch may very rarely be born with the infection.
3. When and where is leishmaniasis a danger to dogs?
- The name sand fly is misleading: sand flies are not on the beach. They are most abundant in gardens, around houses in the countryside, parklands and woodland. Mediterranean vectors bite mostly outdoors, but the vector in Latin America bites equally indoors and outdoors and is very abundant around houses, even in some urban suburbs. The period of activity of all sand fly vectors is from sunset to sunrise.
The dangerous times of year are different in different countries. Around the Mediterranean, leishmaniasis is transmitted from May to September, or later if there is an Indian summer, to October. It is endemic in most of Greece, much of Italy, the Balkans, Malta, southern France, many parts of Portugal and Spain (particularly in the south east and the Balearic islands) and in the humid parts of North Africa.
Among the safe places are the Scandinavian countries, the UK including the Channel Islands, Belgium, Luxembourg, the Netherlands, Germany, northern France, and the mountains of Switzerland.
In endemic places in Latin America, transmission is throughout the year with peaks of danger during the warmest months. The most dangerous places are in north east Brazil. A few years ago, canine leishmaniasis was discovered in hunting packs of fox hounds in many States in the USA (but none west of Kansas).
4. What treatments can be offered to dogs with CanL? How long does treatment last? Is it expensive?
- If a dog is severely affected by the disease, it will be difficult to cure him/her. But if he/she is in the early stages of the illness, there is a good chance of controlling the disease. However, with the therapies currently available, parasitological cure cannot be established.
The clinical signs can go in remission but the dog will probably still be infected at a very low level for life and might have a relapse. The usual treatment is with megulamine antimoniate (Glucantime®) injected either into a vein or under the skin every day for 3-4 weeks. This drug is not always well tolerated by leishmanial dogs and they should be under veterinary supervision throughout treatment.
Glucantime is often combined with a drug called allopurinol, which is given daily by mouth for many months, sometimes for life. Allopurinol is not toxic and can be given to the dog by the owner. Another treatment is with Amphotericin B, which is injected 2-3 times a week for several weeks. Because of its toxicity, the canine patient must be monitored closely by the veterinarian during treatment with this drug.
Correct treatment is expensive and takes time. And there is always a possibility of a relapse in the future and the need to repeat the treatment.
5. What are the early clinical signs of canine leishmaniasis?
- Clinical diagnosis of canine leishmaniasis is difficult. There is a large variety of signs but none of them is pathognomic for the disease. Look for loss of hair, particularly around the eyes and on the muzzle, often spreading to other parts of the body. The skin will be dry with dandruff.
Weeping skin sores or ulcers are common on the head and legs. There is always some weight loss, which can be very severe, although appetite may remain good. Other occasional signs are nose bleeds and eye troubles. Later, the claws may overgrow and become twisted. Kidney failure is a common sign, but this would not be obvious to the owner.
6. How can the vet be sure my dog has leishmaniasis?
- The common clinical signs of canine leishmaniasis may be enough to suggest leishmaniasis to an experienced veterinarian, especially in an endemic area. It is essential to confirm clinical diagnosis with laboratory test.
Diagnosis can be made by direct detection of the parasite by microscopical examination of a small sample of bone marrow or a lymph gland, serological detection such as blood tests for antibodies or the demonstration of parasite DNA in circulating blood cells or a tiny piece of skin (PCR).
7. Is a dog still infectious to sand flies during and after treatment?
- Almost certainly, but the dog will be much less infectious after treatment.
8. Can the disease be transmitted only by a bite of an infected sand fly, or can the infection be passed on, for example, by contact with blood or skin lesions? What is the danger to people or other dogs living close to an infected dog?
- If living in an endemic areas where sand flies are transmitting leishmaniasis, dogs, whether infected or not, should be protected against sand fly bites by keeping him/her indoors from just before sunset until sunup (when sand flies are most active outside), and by fitting the dog with a deltamethrin impregnated collar (Scalibor® ProtectorBand, Intervet International), which will protect the dog from almost all sand fly bites.
This will greatly reduce the risk of dogs infecting sand flies and vice-versa. Whether you live in an endemic area or not, it is a good idea to make sure infected dogs are not in close contact with other dogs. There are very rare reports of dog-to-dog transmission in places where there are no sand flies (and there cannot be transmission by the bite of a vector).
Direct dog-to-human transmission has never been reported, even among veterinarians who have handled hundreds of dogs with leishmaniasis. Nevertheless, it is not a good idea to let babies or toddlers play with a leishmanial dog when it is obviously very sick. Similarly, people with HIV/AIDS or taking corticosteroids, or other medication that might lower their natural resistance to infection, should not handle a sick dog.
9. When humans get infected, can they be cured? Or is leishmaniasis as dangerous to people as it is to dogs?
- Human patients respond much better to treatment than canine patients. Providing treatment is promptly given, human infections by Leishmania infantum are not life-threatening and respond well to the same drugs used to treat dogs.
10. Can canine leishmaniasis be eradicated?
- Not yet. There is no vaccine and there are wild animals (e.g. foxes, jackals, opossums) that can carry the parasite. They can probably infect sand flies, which could then infect dogs.
11. My dog has arthritis, what can I do to help him?
- While this doesn’t have anything to do with canine leishmaniasis, it is a very common question we receive. There are many things you can do to help your dog with arthritis. Glucosamine can help a lot and many supplements exist for this reason. This article should help you learn the basics about glucosamine and dog arthritis.