Leptospirosis in dogs

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Definition and mode of transmission

Leptospirosis is a disease caused by bacteria of the genus Spirochete. In pets, this disease only affects dogs.

Transmission is through the skin or mucous membranes from a contaminated area. Strictly speaking, it is not a contagious disease which requires systematic contact with a sick dog since contamination is carried out via the urine of animals affected by this disease or carrying these bacteria. Thus, rodents are healthy carriers (that is, they live with these bacteria without developing the disease), but they excrete the contaminating bacteria through their urine. Likewise, a sick dog will also excrete these bacteria.

In fact, all areas where rodents live are potentially contaminated with leptospires. These bacteria are able to resist up to 2-3 months under favorable conditions, mainly in stagnant water. Thus, puddles, sewers, backwaters of rivers, marshes… are the areas most “at risk”. We therefore notice that all our environments can be affected, in the city as in the countryside where rodents (mice, rats, nutria, etc.) are legion.

Moreover, this disease is transmissible to humans: it is a zoonosis. It is also known as the sewer workers’ disease, this profession being very often in contact with contaminated stagnant water (but anyone can be contaminated by bathing in backwaters of a river, by being in contact with a dog. who developed this disease…).

Clinical signs of leptospirosis

The symptoms of leptospirosis can be very crude or on the contrary very important:

  • in all cases, the dog is tired, listless, lack of appetite and liveliness
  • often an increase in temperature is present. It can be transient or permanent
  • of vomiting can be reported, as well as a sometimes bloody diarrhea
  • jaundice is also sometimes visible: the dog’s mucous membranes (lips, whites of the eyes, etc.) as well as its skin may turn pale or intense yellow (this is called flaming jaundice)
  • dehydration from vomiting and diarrhea often sets in

All internal organs can be affected, but it is preferentially the liver and kidneys that are the most affected. The dog then presents with severe liver failure (which can cause jaundice) and / or acute kidney failure which can be fatal to the dog.

How to diagnose it?

The diagnosis of leptospirosis requires a complete clinical examination and additional analyzes to check the condition of the internal organs:

  • a blood test is taken to check renal and hepatic functions using biochemical parameters (urea, creatinine, SDMA, liver enzymes, etc.)
  • a blood test also makes it possible to quantify the different blood cells: the red blood cells may be low, we speak of anemia; white blood cells, especially neutrophils, can be elevated, this is called leukocytosis and neutrophilia
  • a urine test can also check your urine glucose level which may be high (without having high blood glucose levels)
  • serological tests are carried out. It is thus possible, within the veterinary practice, to perform rapid tests which confirm the presence of antibodies produced by the dog’s body against leptospires. An additional test can be requested from a specialized laboratory to refine the results and know the exact bacteria involved.

Starting treatment for leptospirosis

Treatment must attack bacteria: sick dogs must be treated with antibiotics specific to these bacteria. It is also necessary to restore the proper functioning of the affected organs: the dog is hospitalized for several days for an infusion with which are associated hepato-renal depurative treatments, anti-emetics, anti-diarrhea … However, if the liver and the kidneys are too affected, it sometimes happens that all the care provided is not sufficient and the prognosis can be very poor. Indeed, if these organs do not return to their normal functioning, the dog can die.

When the infusion is no longer necessary, the dog leaves hospitalization and can return to his home. Antibiotic treatment is very long (often over a month) and follow-up is scheduled throughout the dog’s recovery.

If a dog develops leptospirosis, it should be kept away from other potentially infected animals (other dogs and humans) throughout the treatment period. You should know that excretion in the urine can continue for several weeks after the end of the symptoms and therefore take all precautions (wear gloves, disinfect the place where the dog lives, etc.): your veterinarian and your doctor can direct you to this subject.

Leptospirosis vaccines

There are means of prevention that systematically involve the vaccination of dogs from the age of 7 weeks. Several types of vaccines are possible; your veterinarian will give you the best advice depending on the areas of the dog’s life and the trips you plan to take with him. Annual reminders are necessary to continue to protect your dog throughout his life, since he can be contaminated at any time.

It is very important to vaccinate puppies very early against leptospirosis because, contrary to what is observed for other diseases, the colostrum of the bitch does not contain antibodies against this condition. The puppy is therefore not passively protected by its mother’s antibodies and must build its own means of defense by itself thanks to the vaccine. It is therefore very important to raise the puppies in good hygienic conditions while absolutely avoiding the risk of contamination (avoid garages where mice may have taken up residence, be very careful with outside outings by limiting any contamination by puddles of ‘water…) even if the mother is correctly vaccinated.


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