Canine Leptospirosis

article by Karen Thayne © 1/2007

 


 

 

More commonly known in the dog world as “Lepto”, this zoonotic disease is caused by spirochete bacteria of the genus Leptospira.   It is a gram negative bacteria.     Dogs of any age, sex breed or activity are susceptible to infection.     There are several serovars (types) of Lepto which are found in several species of animals that can cause Lepto in dogs (and humans).     Some of the hosts which carry Lepto are rats, raccoons, pigs, horses and several other types of animals, all of which can cross contaminate to dogs.   This disease can also be spread from our pets to humans

 

Transmission occurs through contamination of water, food, soil, and bedding with infected urine; ingestion of infected tissue and bites of infected animals. 

 

This disease at one time was usually only associated with dogs living in rural areas.   In 2002 a survey was done of veterinary practices in about 20 states that showed an increase of about 25% of confirmed Lepto positive cases.  A study published in 7/1/04 of the JAVMA journal found significant association between Lepto and environmental factors, which included dogs living in rural areas that were urbanized between 1990 and 2000.   As housing developments continue to replace former woodlands, wetlands and farmlands at alarming rates, pets and people are more likely to encounter Lepto than ever before in the past.

 

It is a worldwide disease.   In the United States, one or more serovar of Lepto is found in almost every state, with some having a higher percentage of the various forms of Lepto than others.  

 

Cases in humans have been documented in several states.  During the early 1970’s, 21 cases were reported from MO, OR and TX in humans that came in contact with infected dogs.   In 1998 a human outbreak of Lepto occurred during a Triathlon event when 375 swimmers entered an Illinois lake contaminated with Leptospirosis.    In 2004, 5 cases were reported in humans during a camping and hiking trip in California.   One human case of Lepto was found in a the heart of downtown New York City and was eventually traced to a group of 21 raccoons the woman was feeding on a nightly basis.   

 

In 1986 a 17 year old kennel worker in New Jersey sued a veterinary practice after he developed Lepto from exposure to an undiagnosed infected dog.  The veterinary hospital settled out of court  as among other indicating factors, the vet failed to consider a diagnosis of Lepto and did not isolate the dog.   The initial diagnosis of the dog was pancreatitis. 

 

Cases in dogs have also been documented in almost ever US state.  It is important to note that Lepto can present in dogs with little clinical signs of the disease.    A dog with uveitis at the University of Wisconsin was subsequently found to have Lepto.   Because the dog had no other signs, appropriate precautions were not taken.   The student managing the case developed clinical signs of Lepto which fortunately were mild.   

 

During 1992 to 1994 11 cases of Lepto (Leptospira Interrogans and Grippotyphosa serovar) were identified by the Athens Veterinary Diagnostic Lab in dogs examined at different vet practices in Georgia.    Almost all these dogs were in suburban areas.  Although some were free roaming, one dog was only leash walked with an occasional swim in a local river.  One had a large wooded fenced yard but two others infected had limited outdoor exposure.

 

In North Carolina five confirmed cases of Lepto were seen at an Animal Emergency Center.   All five were positive for the Grippotyphosa, with one dog having a low positive for Pomona.   One of the dogs had been recently vaccinated  but only for serovars Canicola and Icterohemorrhagica.  Three of the dogs were young puppies and were initially parvo suspects.   All animals developed acute renal failure.   One dog died despite aggressive treatment.   One of the ER employees became infected as a result of not wearing gloves during the replacement of a urinary catheter and came in contact with infected urine.    

 

It is important to note here that any owner of a Lepto positive dog should contact their physician for testing.   Clinical signs in people are very vague; headache, nausea, lethargy, body ache.  With timely diagnosis and treatment, Lepto is easily controlled. 

 

In dogs, one documented case of a 5 year old neutered  Labrador mix presented signs after a two mile run with his owner.   He was typically kept indoors.   On 7/17 his initial signs were acute onset, fever (104.7), lethargy, anorexia, diarrhea with vomiting, depression and a reluctance to walk.  Upon veterinarian examination, he was found to be 8% dehydrated, showing abdominal/sublumbar pain and had retinal hemorrhages.   Several tests were run, including a tick panel, fungal panel and Lepto panel.   The initial laboratory findings (7/17) were Anemia, Thrombocytopenia, Leukopenia and a BUN 15; creatinine 1.6.    The initial tick, CPV, and Lepto test (received 7/18) came back normal.    Treatment for suspicion of Lepto was initiated based on differential diagnosis.   A Lepto panel was again run on 7/27 and a positive result to two serovars of Lepto were found – Grippotyphosa and Pomona.   The dog had a complete recovery by 8/17.

 

Incubation is 4 to 12 days before clinical signs develop.  Once the organism enters the body through the mucous membrane, abraded skin or ingestion the virus can rapidly spread to the various organ systems, including liver, kidneys and the central nervous system.    It will replicate in these areas and cause severe damage.     Some of the common signs of Lepto are lethargy, weight loss,  anorexia, petechiae, vomiting, fever, abdominal/lumbar pain, myalgia (stiffness), oculonasal discharge, polyuria/polydipsia, dyspnea, cough, and diarrhea.    Renal disease is associated with lethargy, anorexia and vomiting.   In severe cases, tongue tip necrosis may develop is association with uremia.  

 

In Nov 1996 James Wohl, DVM wrote in the Compendium  “Serovars Grippotyphosa and Pomona are the leading infectious causes of acute renal failure in dogs.”   Acute renal failure is now the most commonly reported presentation of canine Leptospiroris.     The most common infection source is of the Lepto serovars Grippotyphosa, Pomona or Bratislava.   Infection of the Lepto serovars Canicola and Icterohaemorrhagiae are less common now, most likely due to vaccination.  

 

Owners and Veterinarians should consider possible Lepto exposure in dogs with acute or chronic liver or renal signs, bleeding disorders, unexplained central nervous symptoms and fevers of unknown origin.  Uveitis should also be considered as possible exposure to Lepto and appropriate testing may be indicated.     Pain can develop in joints, muscles, inflammation of the kidneys, bowel problems and uveitis (inflammation of the uvea part of the eye) and appropriate therapy should be initiated early in the course of the disease as the pain can be severe and debilitating.  Uremic tongue tip necrosis can be painful and may be alleviated with dilute chlorhexidine rinses, green tea rinses and lidocaine preparations.  

 

Sometimes a Lepto positive dog may go undiagnosed.  Misdiagnosis does happen.   Puppies may be misdiagnoses as having parvovirus or canine distemper.   Dog with acute renal failure, hepatitis, can be misdiagnosed as another disease.  Acute necrotizing pancreatitis and vomiting/diarrhea along with gastroenteritis and pancreatitis can be misdiagnoses as parasitic enteritis. 

 

The most widely used diagnostic test is through microscopic agglutination.   Laboratories evaluate the serum against a panel of five to eight serovars.   Owners of possible infected dogs should insist that a minimum of an 8 panel serovar be done.   The tests are serovar specific and since Lepto  has several different serovars, one or two panels may not accurately diagnose an infected dog.   A high titer of 1:800 or more along with clinical signs is diagnostic.   A convalescent titer obtained 2-4 weeks later confirms the diagnosis with an increase in acute lepto and no change in chronic lepto.   An ELISA test seems to be excellent screening but at this time are not commercially available.   Other diagnostic tests can be done on Urine but generally is used only in early testing.   It can also be used to detect animals that are shedding Lepto.    Indirect fluorescent antibody can be used to identify Lepto in tissue, urine and blood but high sensitivity and low specificity can case false positives.     Abdominal radiographs may document signs of Lepto but is not a good diagnostic tool. 

 

Dogs that present with pain, lethargy or fever of unspecified origin as the initial presenting sign may have normal laboratory results but develop severe renal failure 24 to 48 hours later.   

 

Mild non-regenerative anemia is found in up to 30% of cases and can result in misdiagnosis of chronic renal failure.  Thrombocytopenia is seen in up to 50% of cases and typically is mild to moderate platelet counts, although some dogs may have severe thrombocytopenia.   Uremia  is the most common finding and can range from mild to severe.   Hyperbilirubinemia is seen in fewer than 30% of cases.

 

In mild cases of Lepto, dogs are generally not hospitalized and the first line treatment includes oral Doxycycline.    Other antibiotics such as ciprofloxacin, enrofloxacin, ceftriaxone can be used but can be more expensive and are no more affective than ampicillin or doxycycline.    In more severe cases of Lepto hospitalization is required   Initial IV Fluids with crystalloids is appropriate with potassium added as needed.   IV Ampicillian therapy should be used in dogs who are unable to take oral medications.  Ampicillin therapy should be imitated in any dog with acute renal failure in which lepto is suspected before confirmation of diagnosis.  If obtaining a urine culture, this should be collected prior to initiating Ampicillin therapy.      Low protein diets are not indicated in patients with acute renal failure.   Hospitalized patients that remain anorexic for prolonged periods may need nutritional support.    

 

Even dogs with acute Lepto have a good 70 to 80% recovery rate, however complications can occur that affect survival rate.  Bleeding out, Severe necrosis of the tongue, and Intussusception (the sliding of the bowels causing obstruction) can cause death.   Almost all dogs that   recover have a complete recovery.   In rare cases permanent kidney damage can result.

 

Since this disease is seen in almost every state, Lepto testing should be considered a standard during diagnostic testing of sick animals, especially in dogs that are not vaccinated with a Lepto vaccine.

 

When considering vaccinating dogs for Lepto, owners  should weigh the risk of exposure to this disease to the costs of treatment as a result from exposure.  Depending on the initial diagnosis and severeness of the disease, treatment can run up into the thousands.  Owners should consider homes in areas that are newly developed from woodland, wetlands or farmlands  into suburban living high on the list of possible contact/exposure to Lepto.   Animals that are allowed to free roam, farmland living, frequent traveling or exposure to wildlife (including the nocturnal animals such as raccoons visiting and drinking from common water sources left outside for your dogs) should also be considered for vaccination.    If you should decide to give the Lepto vaccination, there are some considerations to think about.

 

 

Not all vaccines are created equal.  Historically, two serovars Icterohaemorrhagiae and Canicola have been responsible for most cases of Lepto in dogs.   Vaccines that protected against these two serovars have been around for more than 30 years and have been affective in reducing the incidence of disease.  However, they offered no cross protection against the newly rising cases from Grippotyphosa and Pomona.     

 

Some of the Lepto vaccines on the market still only contain protection for only these two types of Lepto serovars.  It is important for owners to ask their veterinarian or vaccine company which Lepto Serovars the vaccine protects against.   Although there are several Lepto serovars, vaccination against  Icterohaemorrhagiae, Canicola, Grippotyphosa and Pomona should be considered as the core protection offered by the vaccine.   Since the vaccine cannot cross protect, using a Lepto vaccine that only protects against one or two types will not give a dog adequate protection.  

 

Owners should consider giving the Lepto vaccine separate from the core vaccinations.   Although there are several 5-7 way vaccines that include Lepto, many owners have reported vaccine reactions when using these type products.  

 

Newly developed Lepto vaccines have shown no increase vaccine reactions when compared to non-Lepto containing vaccines.  In a FDAH Safety Study, 624 dogs received 1223 doses and only 13 reactions were reported in 11 dogs.     Newer studies have also indicated that initial affective immunization for Lepto has been achieved in giving two doses of Lepto vaccine given 3 weeks apart rather than the traditional methods.   Giving a single dose yearly has not proven to be as affective in achieving high Lepto titers.  

 

Vaccine reactions include injection site pain, swelling.  itching at injection site, lethargy and increased thirst.   There have been some cases of Anaphylaxis shock reported.   In extremely rare cases, Thrombocytopenia, IMHA  or death have resulted from vaccines (please keep in mind this is reported in ALL vaccines and less than 1% have ever been reported to have this extreme reaction).

 

In conclusion, owners who are faced with dogs who exhibit any of the symptoms described here should consider their animals having a potential of Lepto infection.   Encourage your vet to test for Lepto if they have not done so.   If you are in an area that has seen an increase of Lepto, known to have had positive cases or are traveling to such areas, consider vaccinating your pet against Lepto.   Owners should also consider any wildlife in the area, including mice, rats, possums, raccoons and skunks as a potential risk to exposure to Lepto.   Hunting and retrieving dogs also have an increased risk.    

 

If your dog is infected, it is important to prevent infection to other dogs and yourself.   Wear gloves and protective gear.    Wash all surfaces, bowls, and bedding with detergent or disinfectant.   Urine, saliva, and stagnant water are sources of potential infection.  Ask your vet to place any of your other dogs who have been in contact with the infected dog on a preventative measure of Doxycycline for at least a week.   Keep the infected dog away from other animals until he stops shedding the virus or  until your veterinarian says it is safe.   If you should develop any flu-like symptoms, see your doctor immediately and disclose the exposure to lepto.

  

The author of this article is not a veterinarian and this article should not be considered as a diagnosis nor treatment for your pet. This article is educational in nature and is not intended as veterinary advice. Readers should seek professional veterinary advice for any health decisions involving their pets.     All information contained in this article was gathered in the research materials listed below.  

 

Research materials:
     1.  Leptospirosis – A re-emerging Disease of Canines… FDP
#CO145T20m

          6/03

  1. Re-Emergence of Canine Leptospirosis, Larry Glickman VMD DrPH, Professor of Epidemiology Perdue University.
  2. Canine Leptospiroris – Kenneth Harkin Reprinted from NAVC Clinician’s Brief June 2005
  3. Serovar-specific prevalence and risk factors for Leptospirosis among dogs: 90 cases (1997-2002) – JAVMA Vol 224 No. 12 2004.
  4. Fort Dodge LeptoVax4 – FDP CO233D 40M

      6.  Diagnosis of Leptospirosis – Carole A. Bolin   Elsevier.  Reprinted from

          Volume 11, No. 3.