Leptospirosis in dogs

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Leptospira ( SEM image )

The leptospirosis of dogs is a worldwide occurring by Leptospira (known as spirochetes , a group of bacteria ) caused contagious infectious disease . It can come in different forms. The mortality rate is around 10%. Infection of humans (see leptospirosis ) by dogs is also possible, leptospirosis is a zoonosis . Other animal species can also develop leptospirosis, with specific leptospiral species being the main pathogen.

history

Leptospirosis was the first to be described in dogs. Hofer first documented it in 1852, 34 years before Adolf Weil described human leptospirosis in Heidelberg , and called it dog typhus . In 1899 it was described by Klett on the occasion of a dog show in Stuttgart , which is why it was initially called the Stuttgart dog disease, a name that is no longer common due to the global occurrence of the disease. In 1933, the researchers Klarenbeck and Schüffner succeeded in differentiating the pathogen causing canine leptospirosis from Weil's disease .

Cause and development of the disease

Leptospira distinguishes about 20 types (genospecies) with about 250 disease-causing serovars . For each serovar there are main hosts, i.e. animal species to which the respective bacterial species has adapted and which represent the actual pathogen reservoir, as well as secondary hosts, which are only occasionally infected by the pathogen type. Dogs are major hosts of Leptospira canicola and L. bataviae . The dog can also act as a secondary host through L. icterohaemorrhagiae (main host brown rat ), L. copenhageni (main host brown rat), L. australis (main host brown rat, pigs ), L. grippotyphosa (main host voles ), L. pomona (main host cattle and pigs) , L. sejroe (main hosts mice, pigs), L. saxkoebing (main hosts mice) and L. bratislava (main hosts hedgehogs, rats and pigs). While in the past only infections caused by Leptospira canicola and icterohaemorrhagiae were clinically relevant in dogs, more recently infections with the other serovars have also been observed, probably due to the mostly existing vaccination protection against the classic pathogens. The distribution of these pathogens varies considerably across Europe. In Germany, L. bratislava and L. copenhageni are currently mainly widespread, and according to more recent information, L. grippotyphosaa , L. icterohaemorrhagiae , L. australis , L. canicola , L. pomona , L. australis , L. saxkoebing and L. . sejroe before.

Leptospira is excreted in the urine of infected animals . The infection occurs through contact through the skin or mucous membranes . The current main route of transmission is the uptake of water contaminated with rat urine in puddles. The disease occurs mainly in late summer and autumn. The incubation period is five to seven days.

During the incubation period, the pathogen spreads in the blood ( bacteremia ), whereupon the body forms antibodies that displace the pathogen from the blood in seven to ten days. They then establish themselves in various organs, especially in the kidney , but also in the liver , spleen and lymph nodes . In the kidney, the leptospy process causes interstitial nephritis with impaired tubular function or even tubular necrosis . The body reacts to bacteremia with the formation of antibodies, which eliminate the pathogens from the blood and most tissues, only leptospira remain in the kidneys and eyes. About 8% of dogs remain permanent carriers.

Symptoms

Clinically, leptospirosis manifests itself in the form of anorexia , vomiting and fever . Later the animals are knocked out, have little movement, have difficulty breathing, sometimes jaundice ( jaundice ), bleeding (hemorrhages) and tissue defects ( erosions caused by necrosis ) of the oral mucosa, muscle tremors ( tremor ) or bloody stools as a result of severe gastrointestinal inflammation ( Gastroenteritis ). The different serovars have different target organs. While the serogroups Canicola and Grippotyphosa mainly damage the kidneys, Icterohaemorraghiae and Pomona mostly affect the liver.

A frequent urination may as a result of an acute inflammation of the kidneys ( nephritis occur). A kidney failure is common and the most serious complication of the disease. It can also lead to an increase in urinary substances in the blood ( azotemia ).

Lung involvement ( severe pulmonary hemorrhage syndrome ) manifests itself with coughing (possibly also coughing up blood ) and shortness of breath. In a retrospective study, lung changes were found in 70% of dogs suffering from leptospirosis; only a third of dogs with severe dyspnea survived the disease.

Differential diagnoses

In addition to specific infectious diseases such as hepatitis contagiosa canis , distemper , ehrlichiosis and babesiosis , other febrile diseases caused by bacteria and viruses must be excluded.

diagnosis

The following diagnostic options are available:

Antibodies can only be detected after one week, which is why this test method does not provide any security for the treatment of acute cases of illness. If the result is negative and there is clinical suspicion of leptospirosis, the test should be repeated after one to two weeks. The gold standard for antibody detection is the microagglutination reaction (MAR). In the early phase of the disease only IgM can be detected, however, in contrast to the IgG which only appears from the second week onwards , the serovars cannot be determined due to cross-reactions. In addition, subclinical infections or vaccinations can trigger the formation of antibodies. Therefore, only titers greater than / equal to 1: 800 indicate an acute infection or a titer increase of four times if the dog has not been vaccinated within the last four weeks. Also high IgM and low IgG in a dog whose vaccination was four weeks or more ago suggests acute leptospirosis. If the time of infection or vaccination was a long time ago, high IgG but low to absent IgM are typical.

In order to be able to detect an acute infection, molecular testing methods such as PCR are recommended. Bacterial nucleic acids can be detected in the blood as early as the first week of illness . In the second week of the disease, leptospiral nucleic acid no longer appears in the blood, but in the urine. Since the time of infection is rarely known, both body fluids should be examined. The sampling must be carried out before any suspicious antibiotic treatment. If only the evidence in the urine is positive, there may also be only a subclinical infection or a permanent excretion . Treatment is nevertheless indicated in order to minimize the risk of infection for humans and other dogs.

therapy

Treatment is given by giving antibiotics . The drug of choice is doxycycline for 14 days, as the active ingredient leads to rapid elimination of the pathogen. If vomiting occurs, another antibiotic such as penicillin G or ampicillin should be injected first. In addition to antibiosis, general supportive treatments in the sense of symptomatic therapy must usually be given. Dialysis is indicated for kidney failure . Oxygen therapy is indicated for severe lung bleeding.

Combat

The simplest form of contraception is to avoid excessive contact with other dogs, although this is not conducive to dog socialization.

For one vaccination there are vaccines from all major manufacturers, also as multiple vaccinations against other dog diseases. The vaccination protection lasts less than a year and with most vaccines only protects against L. canicola and L. icterohaemorrhagiae , but not against the other serovars, which are now much more common. The leptospirosis vaccination is expressly excluded from the current discussion on extending the vaccination intervals and is still recommended annually according to the current vaccination recommendations, but an expansion of the vaccinated pathogen spectrum and a reduction of the vaccination interval to 6 months seem necessary. In 2013, a vaccine was approved by Zoetis that, in addition to L. canicola and L. icterohaemorrhagiae, also protects against L. grippotyphosa and rabies ( Versican L3R ), MSD Intervet launched a vaccine with the components L. canicola , L. icterohaemorrhagiae , L. grippotyphosa in 2013 and L. australis / L. bratislava ( Nobivac L4 ) on the market. For the primary vaccination, two vaccinations are required at an interval of one month, even if a new vaccine with a broader serovar spectrum is used, a new primary vaccination should be given. If the last vaccination was more than 18 months ago, a new basic vaccination is also required. After surviving the disease, the animals should continue to be vaccinated as it is not known how long the immunity lasts.

In Germany, dog leptospirosis is one of the notifiable animal diseases .

literature

  • Katrin Hartmann: bacterial infections . In: Peter F. Suter and Hans G. Nobody (eds.): Internship at the dog clinic . Paul-Parey-Verlag, 10th edition 2006, pp. 291-316. ISBN 3-8304-4141-X

Individual evidence

  1. ↑ a b c d e f g h Michaela Gentil and Doris Breu: Laboratory diagnostics of leptospirosis - a current overview. In: Veterinärspiegel Issue 1 2017, pp. 3–8.
  2. ^ A b T. Gerlach and I. Stephan: Epidemiological situation of canine leptospirosis in Northern Germany in the years 2003-2006. Veterinarian Practice. 35 (2007), pp. 421-429
  3. ↑ a b c d Katharina Gesa Schmitt et al .: Leptospirosis in dogs - diagnostics, zoonotic aspects and prophylaxis. In: Veterinärspiegel , Volume 29, 2019, pp. 131-138.
  4. ↑ B. Kohn et al .: Lung manifestations in canine leptospirosis. In: Kleintierpraxis 55 (2010), pp. 650–651.
  5. ^ JE Sykes, K. Hartmann, KF Lunn, GE Moore, RA Stoddard, RE Goldstein: 2010 ACVIM small animal consensus statement on leptospirosis: diagnosis, epidemiology, treatment, and prevention. In: Journal of veterinary internal medicine / American College of Veterinary Internal Medicine. Volume 25, Number 1, 2011 Jan-Feb, pp. 1-13, ISSN  1939-1676 . doi : 10.1111 / j.1939-1676.2010.0654.x . PMID 21155890 . PMC 3040842 (free full text).
  6. ↑ Annex to Section 1 of the Ordinance on Notifiable Animal Diseases (TKrMeldpflV) in the version published on February 11, 2011 ( Federal Law Gazette I p. 252 ), last amended by Article 381 of the Ordinance of August 31, 2015 ( Federal Law Gazette I p. 1474 )