Leptospirosis in a Dog | Animal Leptospirosis
Leptospirosis in a dog is a bacterial zoonotic disease that is not just limited to dogs, in fact, this disease affects practically all mammals and has a broad range of clinical outcomes. Rats and dogs are potential causes of infection for people. This article will cover in detail what is leptospirosis in a dog, its causes, symptoms, treatment, and prevention.
Other Names: In Animals (Canicola disease in dogs, moon blindness (ophthalmia periodica) in horses, Stuttgart disease).
Cause of Leptospirosis in Dogs
Table of Contents
Leptospirosis in dogs is caused by bacteria that belong to the genus Leptospira. Currently, 2 species of Leptospira have been identified. These are
1- Leptospira interrogans
2- Leptospira biflexa
L.interrogans is pathogenic and responsible for causing leptospirosis in dogs, other animals, and humans whereas L.biflexa is non-pathogenic and is free living in the water. There are over 200 strains or serovars of L.interrogans and all these are identical. Some serovars are host specific while others can infect any host. For example, L.interrogans serovar canicola is the primary causative agent of leptospirosis in dogs but it can also cause leptospirosis in cattle (COLVILLE & BERRYHILL, 2007).
Some Characteristics of Leptospira
- All Leptospira are spirochetes
- They are motile that coil around a central axis
- They are aerobic gram-negative organisms
- Leptospira have characteristic corkscrew-like motility
Host Susceptibility
Leptospirosis can affect any mammal, however, it is more likely to affect cattle, swine, dogs, and horses. There is evidence that cats can be infected with leptospirosis and can shed the organisms. Humans are considered dead-end hosts for leptospiral transmission.
Note: Rodents are the only major group of animals that can carry leptospires in kidneys and shed them throughout their lifespan without clinical manifestations (2013).
Transmission & Pathogenesis of Leptospirosis in a Dog
Leptospirosis is transmitted when an infected dog sheds bacteria in the urine, feces, saliva, and milk. Other susceptible animals get the infection either through direct contact with bacteria or indirect contact. However, the major route of transmission is through contact with urine containing Leptospira.
Humans can get infection either through direct contact with the bacteria or through indirect contact (by using by-products of infected food-producing animals).
Note: Leptospires do not survive in acidic urine, they can survive very well in alkaline urine. As a result, herbivores and other animals whose diet results in alkaline urine are more significant shedders than those who produce acidic urine.
After entering the body of the host, Leptospira circulates in the blood and multiplies in several organs including the liver, kidneys, lungs, genital tract, and central nervous system. Clinical signs start to appear during the bacteremia and tissue colonization phases.
Clinical Signs & Symptoms of Leptospirosis in Dogs
The severity of clinical signs varies and it depends on the host species, the pathogenicity of serovar, age, and the immune status of the animal. The subclinical form is common in maintenance hosts while in incidental hosts, acute febrile illness with multiple organ involvement is reported.
The disease comes in three primary forms:
1- Hemorrhagic (bleeding): Hemorrhagic illness is characterized by a high fever, tiredness, and appetite loss. The mouth and eye whites have a number of tiny hemorrhages (bleeding spots). Vomiting and diarrhea may both be bloody. This type is frequently lethal.
2- Jaundice or icterus (liver): Similar to the hemorrhagic form, the icteric or jaundice variant also has similar initial symptoms and many of the same clinical indications. The presence of a yellow hue (jaundice or icterus) in the mouth and whites of the eyes is another clinical indicator. Yellowing of the skin might occur in extreme cases.
3- Renal (kidney): Renal failure results from the renal form. These dogs may vomit, are anorexic (extremely sluggish), and refuse to eat. They frequently get tongue ulcers, and their breath could smell bad. Diarrhea, excessive drinking (polydipsia), and excessive urination are other symptoms (polyuria). The urine could be stained red (caused by blood). The dog might appear uncomfortable and reluctant to move. In the more advanced stage, the temperature may actually be below normal due to fluctuating fever. In dogs who survive the acute renal form, chronic kidney disease may develop.
Diagnosis of Leptospirosis in Animals
Because the clinical indications of leptospirosis are non-specific and specific laboratory tests often take a few weeks or are not accessible, there is no suitable gold standard test for the identification of the disease. Malaria, dengue, scrub typhus, and other rickettsial diseases, ehrlichiosis, and acute viral infections like influenza are all included in the differential diagnosis. Infection with hantavirus can resemble severe leptospirosis.
Note: The most common serologic test for leptospirosis diagnosis is the microscopic agglutination test (MAT).
Clinicopathological findings of Leptospirosis in a Dog
Typical results of routine blood tests include hyponatremia, mild to moderately elevated transaminases, a slightly elevated white blood cell count, and thrombocytopenia. Leptospirosis, which affects about 50% of patients, may be indicated by an increased creatine kinase level. Proteinuria, pyuria, granular casts, and sometimes microscopic hematuria is frequently seen in urine analyses.
Treatment of Leptospirosis in Dogs
If started as soon as possible, antibiotics including penicillin, ampicillin, and amoxicillin are reasonably effective against the acute stages of leptospirosis. Although the majority of infected dogs need intensive care in the veterinary hospital.
When the dog is recovering, a prolonged course of antibioticsโtypically doxycyclineโis recommended to make sure that all Leptospira bacteria are eliminated and to prevent the dog from becoming a chronic carrier.
Prevention of Leptospirosis in Dogs
Since mice, raccoons, opossums, and skunks are widely seen in both rural and urban settings, it might be challenging to avoid exposure to both wild animals and domestic animals that could serve as Leptospira maintenance hosts. The use of polyvalent inactivated vaccines is the foundation of leptospirosis prevention in dogs.
Conclusion
Leptospirosis in a dog is a zoonotic illness that can spread to other animals and humans and is brought on by infection with one of the pathogenic serovars of the Leptospira genus. Almost all mammals are susceptible to the disease, which has a wide spectrum of clinical symptoms, from a moderate, asymptomatic infection to multiple organ failure and death. Key discoveries include liver, kidney, and respiratory diseases. The best way to diagnose is by combining PCR assay and serologic tests. Although antimicrobial therapy is frequently successful, organ damage might be irreversible.
References
COLVILLE, J. L., & BERRYHILL, D. L. (2007). LEPTOSPIROSIS. Handbook of Zoonoses, 103-107. https://doi.org/10.1016/B978-0-323-04478-3.50029-4
Merck Veterinary Manual. Leptospirosis in Dogs. Available at: https://www.msdvetmanual.com/veterinary/dog-owners/disorders-affecting-multiple-body-systems-of-dogs/leptospirosis-in-dogs
PubMed. Animal Leptospirosis. Available at: https://pubmed.ncbi.nlm.nih.gov/25388134/
ScienceDirect. Leptospirosis. Available at: https://www.sciencedirect.com/topics/veterinary-science-and-veterinary-medicine/leptospirosis
WebMD. What is Leptospirosis. Available at: https://www.webmd.com/a-to-z-guides/what-is-leptospirosis
(2013). Leptospirosis. Clinical Veterinary Advisor, 711-712. https://doi.org/10.1016/B978-1-4160-3969-3.00415-7