With the quick spread of Leptospirosis, here is the most comprehensive article I’ve seen:
LEPTOSPIROSIS
Leptospirosis is a disease caused by infection with Leptospira bacteria. Leptospira are spirochetes that are transmitted between animals by direct or indirect contact. Dogs are most commonly affected and although the disease can occur in cats it is rare and clinical symptoms appear to be mild although very little is known about the disease in this species. Dogs can become infected and develop leptospirosis through exposure of their mucous membranes (or skin with any wound, such as a cut or scrape) to infected urine, urine-contaminated soil, water, food or bedding, through a bite from an infected animal, by eating infected tissues and rarely, through breeding. It can also be passed through the placenta from the mother dog to the puppies. Exposure to infected urine, ingestion of infected tissues, and bite wounds are probably the most common means of direct transmission in the dog. Common risk factors for leptospirosis in dogs residing in the United States include exposure to or drinking from rivers, lakes or streams; roaming on rural properties (because of exposure to potentially infected wildlife, farm animals, or water sources), exposure to wild animal or farm animal species and contact with rodents or other dogs. There has been a surge in the diagnosis of infected dogs in urban areas as a result of the burgeoning rodent population associated with urban homeless encampments. Affected soil and water can remain infective for anywhere from up to 3-6 months. Leptospirosis is indeed a zoonotic disease meaning that infection can be passed from humans to animals and from animals to people. Infection in people can cause flu-like symptoms and can cause liver or kidney disease. In the United States, most cases of human leptospirosis result from recreational activities involving exposure to infected water; infection resulting from contact with an infected pet is much less common, but it is possible.
Infection of dogs with leptospires results in illness of varying severity, depending on the infecting strain, geographical location, and host immune response. Some infected dogs do not show any signs of illness, some have a mild and transient illness and recover spontaneously, while others develop severe illness and death, often a result of renal injury. The incubation period is approximately 1 week but can vary depending on the virulence of the strain and the immunity of the host. The most common targeted organs are kidneys and liver. The lungs can also be affected, probably due to leptospiral vasculitis and focal hemorrhages. Fever occurs early in the course of illness, and may be accompanied by shivering, generalized muscle tenderness, respiratory distress from pulmonary hemorrhage, uveitis and reluctance to move. Dogs presenting with acute renal failure may show polyuria, polydipsia, dehydration, vomiting, diarrhea, inappetence, lethargy or abdominal pain or some combination of these signs. Dogs may develop jaundice, which means the lining of the mouth and the whites of the eyes turn yellow.
There are several specific tests for diagnosing leptospirosis, but the two most common ones are the DNA-PCR test and the microscopic agglutination test (MAT). Infection can be diagnosed with either test, but each has weaknesses, and in some situations both tests may be needed to reach a diagnosis. Routine tests should always be performed prior to or in conjunction with specific testing and should include a complete blood count (CBC), complete biochemical profile, urinalysis and survey radiography. The most common abnormalities found on routine testing in dogs with leptospirosis include:
- CBC:increased numbers of white blood cells (indicating infection and tissue damage), decreased numbers of platelets (indicating infection and severe disease), and sometimes, decreased numbers of red blood cells (due to bleeding).
- Serum biochemistry:high liver and/or kidney values (indicating damage to the liver and/or kidney), and abnormal values for sodium, chloride, phosphorous, potassium (indicating damage to the kidney and unbalanced metabolism, indicating serious illness).
- Urinalysis:dilute urine, the presence of protein, and evidence of inflammation (all of which signal kidney damage).
Treatment for a dog suspected of having Leptospirosis should be prompt and aggressive depending upon the clinical signs observed and the results of laboratory testing. Antibiotics are usually very effective in treating leptospirosis, and most dogs respond quickly once antibiotics are started. The most effective antibiotic currently utilized is Doxycycline and should be administered for at least 14 days and up to 28 days in many cases. In addition to antibiotic therapy, dogs with severe kidney or liver damage may require hospitalization for intravenous fluid treatment to correct dehydration and electrolyte abnormalities and to receive medications that decrease vomiting or nausea, and to protect the stomach as well as additional supportive care. Throughout the period of initial hospitalization re- evaluation of the current clinical status and response to therapy is achieved by repeating blood and urine analysis. As mentioned previously, the prognosis for severely infected dogs is guarded because overwhelming infection may result in irreversible organ damage and rapid deterioration and death in spite of appropriate treatment.
There are many strains of Leptospira bacteria that can cause disease. Although the current vaccines do not protect against all strains of leptospires, they do provide protection against the most common ones. The most effective vaccines protect against the four most prevalent serovars of Leptospira which are Icterohaemorrhagiae, Canicola, Grippotyphosa and Pomona. If your dog has had leptospirosis before, it is still important to get it vaccinated as your dog can still become infected by a different strain. Subclinical seroconversion has been documented in some dogs living in the same household with dogs with leptospirosis, possibly as a result of common exposure. 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. Evidence of recurrent leptospirosis in dogs after proper treatment is lacking. Nevertheless, annual vaccination for dogs that have recovered from leptospirosis should be considered, because such dogs are at risk of ongoing exposure, and whether or not life-long immunity results from natural infection is unknown.
In summary, Leptospirosis is a significant pathogen in dogs and is no longer relegated to exposure to infected lakes, streams and rural areas but is becoming more firmly entrenched in urban areas as a result of an increasing rodent population. Prompt evaluation and treatment by your Veterinarian will result in early diagnosis and treatment which may indeed be life-saving. If you have a dog that has contracted Leptospirosis, in addition to veterinary guided therapy these few easy steps can help prevent disease transmission to other pets and people in the household:
- Clean surfaces that may be contaminated by urine from an infected dog – wear gloves and use antibacterial cleaning solution or a solution of 1 part household bleach in 10 parts water and disposable paper towels to clean.
- Block off an outdoor area where your dog can urinate separate from areas used by your family to play, eat, or garden.
- Always wash your hands after handling your dog or anything that might have your dog’s urine on it.
Dr. Alan Schulman DVM DACVS
References available upon request