Leishmania in dogs: let’s find out what it really is, why “vaccinated” dogs can still get infected, and how to prevent infection.

leishmania nei cani risposta immunitaria e vaccino 2
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Leishmania, the dreaded disease that affects our dogs, relies on a vector in order to develop into its infectious form in mammals: the phlebotomist.

Leishmania is transmitted by phlebotomas, very small, about 2-3 mm, silent-flying, pale yellow ochre insects.

Phlebotomus (also known as pappatacio) strikes mainly from May to October and always at night, from dusk to dawn.

Infection occurs through the bite it inflicts on the host mammal.

The phlebotomist not only inoculates the parasite but also promotes its initial penetration and subsequent spread through saliva, which is rich in vasodilating substances that facilitate the spread of infection in the animal ‘s body.

Which animals can contract leishmania?

Leishmania affects not only animals but also humans.

Among animals, the dog is the most at risk.

There is no transmission given by human-dog and dog-dog proximity.

It is always the insect that acts as the infectious vehicle, and in order to transmit the virus it must go through its own biological cycle.

Not all infected animals become truly leishmanic: the outcome of the infection is closely related to the type of immune response that is triggered.

Why does dogs get leishmaniasis?

The ‘body of the dog that comes into contact with the parasite, Leishmania Infantum, can respond in two different ways, and the establishment of either situation will determine or not, the onset of the disease.

It all depends on the reaction of the dog’s immune system.

There are resistant dogs and receptive dogs

We can divide dogs into two categories: those
to Leishmania and those
receptive ones

Resistant dogs produce a substance, called TH1: this is called cell-mediated immunity activation.

It is a response by the immune system that does not involve antibodies but rather involves the activation of killer cells of the pathogen, whether virus or bacterium, called macrophages.

Receptive dogs, on the other hand, produce TH2: this substance activates the antibody immune response, which, paradoxically, is responsible for the progression of infection to disease.

The continuous stress on immunocompetent cells results in immunological imbalance: antibodies are ineffective and the pathogen cannot be eliminated.

The establishment of this type of immune response inevitably leads to the development of clinical symptoms of the disease.

What really is leishmania?

Canine leishmania can be considered a consequence of specific immunodeficiency rather than a simple infection.

The immune system is more complicated than previously thought, and at least the two different categories, Th1 and Th2, are schematically distinguished.

The fundamental question, which remains essentially unresolved, concerns knowledge of the factors that induce a predominantly Th1 or predominantly Th2 response.

If leishmania is an immunodeficiency, what is the vaccine for?

The mechanism of action of vaccines is simple: they cause increased levels of antibodies to a disease-specific antigen (virus or bacterium).

In the case of Leishmania, what has been presented as a “vaccine,” technically speaking, is actually not.

The goal of this product is not aimed at antibody production but is to stimulate the triggering of a cell-mediated response.

The ‘inoculation does not zero out the probability of a dog becoming ill but only reduces the likelihood of it happening.

The vaccinated dog may still become infected, and the infection may actively develop or not.

Vaccination against leishmaniasis is only complementary to existing repellent products: the only practically feasible interventions, which provide variously encouraging results, are those to prevent phlebotomist bites.

Hopes for vaccination and new, finally effective, therapeutic principals are now focused on research investigating the intimate relationships-genetic and molecular-between Leishmania, macrophage cells, and the Th1/Th2 immune response.

Is leishmania curable?

Canine leishmaniasis is, yes, treatable but not curable parasitologically.

The disease has a sometimes very long incubation period, but detecting the presence of the parasite through periodic blood testing allows timely implementation of appropriate treatment.

When the dog’s condition is not critical, action is taken in time, and kidney function is not irreparably compromised, it normally results in the disappearance of some symptoms, especially skin symptoms.

The dog can lead, even for a long time, a satisfactory existence with a good quality of life.

It is also true that, unfortunately, the dog may also exhibit relapses that require re-treatment, so clinically cured individuals need to be checked periodically.

What are the symptoms of canine leishmaniasis?

Not always immediately identifiable, leishmania symptoms can appear singly or in groups, and the greatest damage involves internal organs.

The most common are:

  • ulcers in the peri-ocular area
  • abnormal nail growth
  • nosebleed
  • Desquamative dermatitis localized mainly on muzzle, paws and limbs

And again:

  • enlargement of lymph nodes and spleen
  • anemia
  • polyarthritis
  • renal failure

How is leishmania detected and prevented?

To detect the disease, it is important to monitor for suspicious symptoms, take the dog to the veterinarian periodically, and have blood and urine tests at least once a year.

It is critically important to make year-round use of specific repellent products expressly designed and indicated to protect against phlebotomist stings.

Always consult your veterinarian for advice on choosing the best prescriptions, and have your dog checked regularly in order to make sure it has not been infected.

We would like to remind you, in this regard, that at La Veterinaria Clinic specific testing for infectious diseases is available and that our Staff Veterinary Doctors are always at your complete disposal for regular preventive examinations.

La Veterinaria Clinic is always open, every day, including holidays, and with First Aid Service from 8 pm to 8 am.

For the joy of seeing them HAPPY.

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