Leptospira spp

From Dog
Scanning electron micrograph of Leptospira spp. Notice the corkscrew appearance of the bacterium[1]
Lung of a dog which died due to pulmonary hemarrhagic syndrome due to Leptospira[2]
Tubulointerstitial nephritis in a dog which died from Leptospirosis[3]
Pulmonary petechiations associated with leptospirosis in a dog[3]

Leptospirosis is a multisystemic disease caused by Leptospira spp zoonotic spirochaete bacteria.

This bacteria causes endemic disease in urban dogs and humans in tropical and temperate countries[4].

Leptospirosis is considered an occupational disease of persons engaged in veterinary, agriculture, sewage, forestry and abattoir works[5].

Leptospira are thin, motile spirochetes with a hook-shaped end. Both saprophytic and pathogenic species exist in nature. Saprophytic species, such as Leptospira biflexa, live in water and soil and do not infect animals[6].

Naïve animals become infected by contact of intact mucous membranes or abraded skin with infected urine or urine-contaminated soil, water, food or bedding[7].

Upon gaining entry into the host, the spirochetes multiply rapidly upon entering the blood, disseminating to many tissues systemically. Large numbers can subsequently be found in the liver, spleen, kidney and brain. Following clearance by humoral antibodies, bacteria persist in the renal pelvis, where shedding in urine completes the cycle[8].


Numerous species of leptospira have been reported to infect dogs, although Leptospira interrogans sensu lato and Leptospira kirschneri are the most important serovar which affects canids.

All recognized species of Leptospira are categorized into 24 serogroups and 250 serovars, based on the expression of surface-exposed lipopolysaccharide[9].

Species which have been reportedly pathogenic to dogs include:

  • Leptospira kirschneri
- Leptospira kirschneri ser gryppotyphosa (raccoon, skunk, possum, vole)[10]
  • Leptospira interrogans
- Leptospira interrogans ser canicola (dog, cattle, pigs)[11]
- Leptospira interrogans ser icterohaemorrhagiae (rodents)
- Leptospira interrogans ser pomona (cattle, pigs, possum)
- Leptospira interrogans ser hardjo (cattle)
- Leptospira interrogans ser copenhageni[12]
- Leptospira interrogans ser australis bratislava (pigs, rodents)
- Leptospira interrogans ser altodouro[13]
- Leptospira interrogans ser mozdok[14]
- Leptospira interrogans ser pyrogenes[15]
- Leptospira interrogans ser autumnalis[16]
- Leptospira interrogans ser cynopteri
- Leptospira interrogans ser tarassovi
- Leptospira interrogans ser djasiman[17]
- Leptospira interrogans ser ballum[18]
- Leptospira interrogans ser sejroe[19]
  • Leptospira licerasiae ser varillal[16]
  • Leptospira borgpetersenii group B
  • Leptospira noguchii ser australis[20]
  • Leptospira santarosai
  • Leptospira weilli
  • Leptospira alexanderi[21]

The pathogenic relevance of the serovar classification has been problematic, because both pathogenic and nonpathogenic leptospires can belong to the same serovar, presumably as a result of transfer of genes determining serotype among different species[22].

Clinical signs

The majority of infections in dogs are subclinical or asymptomatic. Entire male dogs appear more predisposed due to a proclivity for roaming. Seasonal variations occur, with heavy rainfalls, especially in monsoon seasons are more common[23]. No clear correlation has been made between the suspected infecting serovar and clinical symptoms in naturally occurring cases[24][25].

Leptospirosis should be suspected in any presenting ill dog with signs of renal or hepatic failure, uveitis, pulmonary hemorrhage, acute febrile illness or abortion.

In peracute infections, leptospiremia and sudden death may be observed. Acute infections present as fever, anorexia, icterus, vomiting, dehydration, lumbar pain and myalgia associated with disseminated infection and renal failure are common. Hepatitis, acute nephritis, pulmonary hemorrhagic syndrome and disseminated intravascular coagulation (DIC) may occur in rapid and severe leptospirosis. Meningitis does not appear to be a feature of this disease.

Chronic infections often present as waxing and waning fever, myalgia, renal pain, hepatomegaly, ascites, melena, epistaxis, chronic renal disease, coagulopathy and hepatoencephalopathy.

Hematology is often normal, but abnormal findings include a mild to moderate neutrophilic leukocytosis without a left shift, a mild thrombocytopenia and regenerative anemia.

Blood biochemistry tests usually reveal elevated urea and creatinine concentrations, as well as hyponatremia, hypochloremia, hypokalemia, and hyperphosphatemia.


A tentative diagnosis can be made on clinical history, presenting symptoms at prevalence of leptospirosis in the region.

Urinalysis may reveal presence of spirochaetes, as well as the presence of glucosuria, proteinuria and bilirubinuria.

A definitive diagnosis requires confirmatory serology (ELISA[26], microscopic agglutination assays[27] or PCR analysis) or culture of organism from blood or urine samples[28]. Serology testing usually shows a serum titer of ≥ 12,800 or a four-fold rise over a 2 - 4 week period[29], but interpretation must take into account recent vaccination history[30]. Recent vaccinations do not appear to interfere with real-time PCR identification of acute leptospira infection[31].


Fluid therapy is the cornerstone of the management of patients with leptospirosis to minimize renal and hepatic damage, improve tissue perfusion and reduce bleeding tendencies due to DIC[32].

Antiemetics such as metoclopramide may be necessary to control vomiting in severely moribund patients.

The antimicrobial of choice is doxycycline (5 mg/kg orally every 12 hours for 2 weeks), but amoxycillin/clavulanate or azithromycin[33] may be efficacious.

Renal replacement therapy with intermittent hemodialysis or continuous renal replacement therapy can be life-saving for many dogs with severe anuric leptospirosis[34] and is indicated in dogs with inadequate urine output that are developing volume overload, hyperkalemia, BUN > 80 mg/dL, or signs of uremia that are not responsive to medical management. Recovery of adequate renal function usually occurs within 2–4 weeks of starting dialysis.

Dogs with pulmonary hemorrhagic syndrome may require oxygen therapy and, if severe, mechanical ventilation. Studies of human patients with LPHS showed improved outcome after cyclophosphamide therapy and plasma exchange[35][36].

Survival rates of approximately 80% have been reported, both among dogs treated conservatively and those treated with dialysis[34].

However, long-term complications of this disease include decompensated chronic renal disease and chronic active hepatitis and patients may require long-term monitoring.


Immunity, whether natural or vaccine-induced, is serogroup-specific with the infecting serovars varying according to geographical locality[37]. Immunization is effective against most serovars, with inactivated tetravalent vaccines (containing serovars Icterohaemorrhagiae, Canicola, Grippotyphosa, and Pomona) readily available to most veterinary clinics in the USA[38] and bivalent vaccines (containing Icterohaemorrhagiae and Canicola) are available in North America, Europe, South Africa and Australia. Annual vaccination is recommended for at-risk dogs.

Because of the zoonotic potential of leptospirosis, treatment of other dogs in the household that may have been coincidentally exposed to a source of leptospires in the environment is recommended.


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