Ehrlichiosis

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Sections available in full article Introduction, Presenting signs, Acute presentation, Geographic incidence, Age predisposition, Breed predisposition, Pathogenesis, Etiology, Predisposing factors, Pathophysiology, Timecourse (incubation, duration), Epidemiology (population dynamics), Diagnosis, Presenting problems, Client history, Clinical signs, Diagnostic investigation, Confirmation of diagnosis, Gross autopsy findings, Histopathology findings, Differential diagnosis, Treatment, Initial symptomatic treatment, Standard treatment, Monitoring, Prevention, Control, Prophylaxis, Sequelae, Prognosis, Reasons for treatment failure, Sources, Publications, Vetstream contributor(s),
Contributors Dr Kim Willoughby BVMS PhD MRCVS
Ms Maggie Fisher BVetMed CBiol MIBiol DipEVPC MRCVS
Dr Alex Morrow MVB BA PhD MRCVS
Dr Stephen Barr BVSc MVS PhD DipACVIM
Synonyms Canine rickettsiosis Canine hemorrhagic fever Tropical canine pancytopenia (severe chronic phase) Lahore canine fever Nairobi bleeding disease, Canine hemorrhagic fever

Introduction

  • Little recorded information about the disease in cats.
  • Cause : serious tick-borne rickettsial infections of dogs and cats acquired in parts of the tropics, sub-tropics, warm temperate regions and Sweden.
  • Usually tick transmitted.
  • Signs : non-specific in the acute phase, sudden onset of fever, depression and anorexia.
  • Diagnosis : antibiotics with efficacy against rickettsia.
  • Concurrent infection with other tick borne infections may occur.
  • Treatment : doxycycline 10 mg/kg daily for 3 weeks.
  • Infection with Ehrlichia spp is much more commonly recognized in dogs than cats. In the latter relatively little is known of the disease, including the identity of the Ehrlichia species involved and epidemiology.
  • This component will review what is known of infection in the cat and then infection in the dog, since details of infection in this species are better understood.

Diagnosis

Clinical signs

Canine Monocytic Ehrlichiosis - acute syndrome
  • Sudden onset.
  • Depression.
  • Fluctuating temperature.
  • Splenomegaly.
  • Lymphadenopathy.

Canine Monocytic Ehrlichiosis - chronic syndrome

  • Dyspnea.
  • Ventral edema.
  • Petechial and ecchymotic hemorrhages on hairless areas of skin and mucous membranes.
  • Epistaxis.
  • Hematuria.
  • Prolonged bleeding time on venepuncture.
  • Hypotension and shock secondary to blood loss.
  • Ocular changes:
    • Conjunctivitis.
    • Corneal edema/opacity.
    • Anterior uveitis aqueous flare.
    • Hyphema.
    • Tortuous retinal vessels and focal chorioretinal lesions.
    • Subretinal hemorrhages.
    • Retinal detachment.
    • Blindness.
  • Neurological signs:
    • Ataxia.
    • Upper motor neuron dysfunction.
    • Central and peripheral vestibular dysfunction.
    • Hyperesthesia.

Canine Granulocytic Ehrlichiosis

  • Clinical signs similar to a mild form of acute canine monocytic Ehrlichiosis.
  • Polyarthritis.

Canine cyclical thrombocytopenia

  • Clinical signs similar to a mild form of acute canine monocytic Ehrlichiosis.
Canine monocytic Ehrlichiosis - acute phase
  • Limb and scrotal edema.
  • Respiratory signs.

Canine monocytic Ehrlichiosis - chronic phase

  • Skin lesions - alopecia and crusting.

Diagnosis

Differential diagnosis

Acute form
  • Babesiosis  Babesiosis  .
  • Canine distemper.
  • Immune thrombocytopenia purpura  Immune-mediated thrombocytopenia  .

Chronic form

  • Warfarin poisoning  Anticoagulant rodenticide poisoning  .
  • Autoimmune hemolytic anemia  Anemia: immune-mediated hemolytic  .
  • Trypanosomiasis.

Sequelae

Prognosis

  • Good - when the acute phase has been treated properly.
  • Chronic infections may occur in animals which haven't been properly treated, ie treated for too short a period, leading to the development of tropical canine pancytopenia which is refractory to treatment.
  • Grave - in the severe chronic form of canine monocytic Ehrlichiosis.

Reasons for treatment failure

  • Recovered animals are usually immune but become carriers and relapses may occur if stressed.
  • Affected dogs are likely to have babesiosis as well as ehrlichiosis.
  • Failure to treat early and for sufficient length of time.

Sources

Publications

Refereed papers

  • Murphy K & Shaw S (2004)Disease risks for the travelling pet: Ehrlichiosis.In Practice.26(9), 493-497.
  • Bjoerdorff A, Svendenius L, Owens J H & Massung R F (1999)Feline granulocytic ehrlichiosis -a report of a new clinical entity and characterization of the infectious agent.JSAP4020-24.
  • Trees A & Shaw S (2001)Imported diseases in small animals.In Practice21482-491.
  • Peaves G M, Holland C J, Dutta S K, Moore A, Rich L J, Lappin M & Richter K (1997)Suspected ehrlichial infection in five cats from a household.JAVMA210(2), 231-234.
  • Harrus S & Hylton B (1997)Canine Monocytic Ehrlichiosis - An Update.Comp Cont Educ Pract Vet19, 431-444 (comprehensive review).

Other sources of information

  • Ramsey I, Gunn-Moore D & Shaw S (2001)The hemopoietic and lymphoreticular systems.InManual of canine and feline infectious diseases.Eds I Ramsey and B J Tennant. Gloucester: British Small Animal Veterinary Association. pp. 65-88.

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