Ehrlichiosis

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Sections available in full article Introduction, Presenting signs, Acute presentation, Geographic incidence, Age predisposition, Breed predisposition, Pathogenesis, 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, Expected response to treatment, Reasons for treatment failure, Sources, Publications, Vetstream contributor(s),
Contributors Ms Maggie Fisher BVetMed CBiol MIBiol DipEVPC MRCVS
Dr Lisa Moore DVM DipACVIM
Dr Alex Morrow MVB BA PhD MRCVS
Dr Bryn Tennant BVSc PhD CertVR MRCVS
Synonyms Canine rickettsiosis, Canine hemorrhagic fever, Tropical canine pancytopenia (severe chronic phase), Lahore canine fever,Nairobi bleeding disease

Introduction

  • Cause : serious tick-borne rickettsial infections of dogs acquired in parts of the tropics, sub-tropics, warm temperate regions and Finland.
  • Signs : non-specific in the acute phase, sudden onset of fever, depression, anorexia and in the chronic phase, hemorrhages including epistaxis.
  • Diagnosis : antibiotics with efficacy against rickettsia.
  • Concurrent infection with Babesiaspp and Leishmania infantumcommon.
  • Treatment : doxycycline 10-20 mg/kg daily for 3 weeks.
  • Prognosis : good when acute phase is treated properly; guarded if proceeds to tropical canine pancytopenia; guarded if severe chronic form of canine monocytic Ehrlichiosis.
    Print off the owner factsheet on Ehrlichiosis Ehrlichiosis to give to your client.

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 Epistaxis.
  • Hematuria Hematuria.
  • Prolonged bleeding time on venipuncture Jugular venipuncture.
  • Hypotension and shock secondary to blood loss.


Canine Monocytic Ehrlichiosis - chronic phase
  • Ocular changes:
    • Conjunctivitis Conjunctivitis.
    • Corneal edema/opacity.
    • Anterior uveitis Uveitis aqueous flare.
    • Hyphema 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.
  • Skin lesions - alopecia Skin: alopecia - overview and crusting.

    Canine Granulocytic Ehrlichiosis

  • Clinical signs similar to a mild form of acute canine monocytic Ehrlichiosis.
  • Polyarthritis Arthritis: polyarthritis - GreyhoundArthritis: polyarthritis - idiopathic

    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.

Diagnosis

Differential diagnosis



Acute form
  • Babesiosis Babesiosis.
  • Canine distemper Canine distemper disease.
  • Immune thrombocytopenia purpura Immune-mediated thrombocytopenia.
Chronic form
  • Warfarin posioning Anticoagulant rodenticide poisoning.
  • Immune-mediated 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.
  • Guarded - in the severe chronic form of canine monocytic Ehrlichiosis.
  • Previously affected animals may not be immune.

Expected response to treatment

  • Treated dogs become seronegative within 9 months.

Reasons for treatment failure

  • Recovered animals may 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.
  • Egenvall A, Lilliehook et al(2000) Detection of granulocytic Ehrlichia species DNA by PCR in persistently infected dogs. Vet Rec 146 , 186-190.
  • Suksawat J et al(2000) Seroprevalence of Ehrlichia canis, Ehrlichia equi and Ehrlichia risticii in sick dogs from North Carolina and Virginia. J Vet Intern Med 14 , (1) 50-5.
  • Harrus S & Hylton B (1997) Canine Monocytic Ehrlichiosis - An Update. Comp Cont Educ Pract Vet 19 , 431-444 (Comprehensive review).

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