COMMON BLOOD PARASITES IN DOGS AND CATS

Dr. Abhishek KalundiaB.V.Sc. & A.H., M.V.Sc., Ph.D. (pursuing)The Alpha and Omega Pet HospitalHyderabad, Telangana State – 10India

List of Blood parasite and their primary hosts Veterinary Practice

1. Ehrlichiosis & Anaplasmosis (Dogs and Cats)2. Babesiosis (Dogs)3. Cytauxzoonosis (Cats)4. Hemotropic mycoplasma (Dogs and Cats)5. Hepazoonoses (Dogs)6. Trypanosomiasis (Dogs)7. Schistosomiasis (Cattle)8. Theileriases (Cattle)

Anaplasmataceae family - Ehrlichia, Anaplasma, and Neorickettsia Anaplasma traditionally refers to a disease of ruminants. Obligate intraerythrocytic bacteria of the order Rickettsiales. A phagocytophilum - formerly known as both E equi -

predominantly in granulocytes. A platys - infectious cyclic thrombocytopenia of dogs - platelets. Ehrlichia canis - Canine monocytic ehrlichiosis- human

infection occasionally reported - monocytes . E chaffeensis - monocytic form of illness in dogs. E ewingii - primarily infects the granulocytes. E muris–like (EML) agent - possible pathogen of dogs or cats -

currently unknown.

Epidemiology E chaffeensis and E

ewingii have sylvan cycles in the environment that involve tick species (Amblyomma americanum/lone star tick), dogs and wildlife reservoir hosts.

EML - Ixodes scapularis (black-legged tick)

A phagocytophilum - Ixodes scapularis (black-legged tick)

A platys - R sanguineus - Coinfection with E canis (same tick vector).

E chaffeensis, E ewingii, and A phagocytophilum are considered zoonoses.

Clinical FindingsAcute E canis Chronic E canis Warmer months- greatest activity of the tick vector Depending on the strain of organism and immune

status of the host. Reticuloendothelial hyperplasia Fever Generalized Lymphadenopathy Splenomegaly Thrombocytopenia (Petechiae May Not Be

Evident) Normochromic Anemia; Leukopenia; Or Mild

Leukocytosis. Vasculitis and  tendecies of IMHA/IMTP. Variable signs of anorexia, depression, loss of

stamina, stiffness and reluctance to walk, edema of the limbs or scrotum, and coughing or dyspnea may be seen.

Cases May Present At Any Time Of Year.

Marked Splenomegaly Glomerulonephritis - Renal Failure Interstitial Pneumonitis Anterior Uveitis Meningitis With Associated

Cerebellar Ataxia, Depression, Paresis, And Hyperesthesia.

Severe Weight Loss Pancytopenia With Bleeding

tendenciesDogs infected with A platys generally show minimal to no signs of infection despite the presence of the organism in platelets. The primary finding is cyclic thrombocytopenia, recurring at 10-day intervals. 

Diagnosis Treatment Combination Of 1. Clinical Signs2. Positive Serum Indirect

Fluorescent Antibody (IFA) Titer

3. PCR4. Response To Treatment

Doxycycline in dogs is 5–10 mg/kg/day, PO or IV, for 10–21 days

Two doses of Imidocarb Dipropionate (5–7 mg/kg, IM), 2 wk apart

Supportive therapy - Platelet or Whole Blood Transfusions - if hemorrhage is extensive.

Babesiosis

Intraerythrocytic protozoan parasites of the genus Babesia. Clinical disease in dogs is variable and can be sublinical, chronic, or life

threatening. Large and small—based on intraerythrocytic formA. Large (3–7 µm long; Single or pair tear-drop forms)

a. B gibsoni: worldwide b. B conradae: southern California only c. B microti-like: SpainB. Small (1–3 µm long; Signet-ring form)

d. B canis vogeli: worldwide e. B canis canis: Europe f. B canis rossi: South Africa g. B coco: United States

Pathology

Intra- and extravascular destruction of RBCs or direct parasitic injury or subsequent oxidative stress or IMHA = Hemolytic anemia

IMTP or DIC = Thrombocytopenia

Lethargy Pale mucous

membranes with icterus Splenomegaly pyrexia

PERIPHERAL Blood Smear

Canine blood smear of Babesia canis showing paired large merozoites (pair tear-drop forms)

Canine blood smear of Babesia gibsoni showing single merozoites (signet-ring form).

Diagnosis Treatment Thrombocytopenia is the most

common feature regardless of the babesia spp.

Macrocytic anemia Hyperglobulinemia Hyperbilirubinemia, Increased liver enzyme

activities, azotemia Multiplex PCR (to rule out

coinfection), and DNA sequencing

Imidocarb dipropionate (6.6 mg/kg IM once, repeat in 7–14 days) - Treatment of choice for B canis vogeli (but is ineffective for clearance of B gibsoni and B conradae)

Pretreatment with Atropine (0.02 mg/kg SC 30 minutes before imidocarb) reduces cholinergic side effects (ie, salivation, lacrimation, vomiting, diarrhea, tachycardia, dyspnea)

Clindamycin (25 mg/kg PO q12h), + Metronidazole (15 mg/kg PO q12h), + Doxycycline (5 mg/kg PO q12h) have been associated with clearance of B gibsoni after administration for ~3 months - true treatment efficacy is unknown.

Diminazene aceturate (3.5–7 mg/kg SC or IM q1–2wk) is effective against B canis.

Cytauxzoonosis

Emerging, life-threatening infectious disease of domestic cats (and dogs) - tick-transmitted protozoan parasite Cytauxzoon felis.

Cytauxzoon spp are classified as part of the family Theileriidae (includes Babesia and Theileria organisms)

Dermacentor ticks

Blood film from a cat

A – 10XThe leukocyte count is decreased, and neutrophils exhibit Döhle bodies and increased cytoplasmic basophilia and vacuolation consistent with moderate to marked toxic change (broken arrows).

B – 40XErythrocytes show several small signet-ring basophilic intracellular organisms consistent with Cytauxzoon organisms (arrows).

Cytauxzoonosis

Diagnosis Treatment Anorexia, Dehydration, Pallor, and

Icterus are common. Temperatures >105°F Ataxia Peripheral blood smear stain

(Giemsa) Nonregenerative Anemia,

Leukopenia, and Thrombocytopenia due to DIC

Hepatosplenomegaly, Pulm Congestion or Cardiomegaly with effusion.

Controversial- infection is fatal

Supportive - aggressive IV fluid therapy + blood transfusions + Enoxaparin to prevent DIC. Medications

Standard of treatment has yet to be determined.

Hemotropic Mycoplasmas

Previously known as Haemobartonella and Eperythrozoon and formerly classified as Rickettsial organisms.

Clinically significant Hemolytic Anemia - FELINE INFECTIOUS ANEMIA (FIA)

REGENERATIVE ANEMIA IN DOGS AND CATS

Hemotropic Mycoplasmas

Transmission Clinical signs

Blood transfusion Verticle transmission

(transuterine) Horizontal transmission

(saliva, on gingiva, and on claw beds of infected cats)

Vector borne (lice, flies, ticks, and mosquitoes)

Coinfection with multiple hemoplasma species + Feline Leukemia Virus (FLV) or Feline Immunodeficiency Virus(FIV).

Acute Extravascular Hemolytic Anemia.

lethargy, anorexia, and fever, with splenomegaly and icterus.

Diagnosis : 1. PCR2. Blood Smear staining- Romanowysky

Dog with Mycoplasma haemocanis infection

Treatment

Doxycycline (10 mg/kg/day, PO, for a minimum of 2 wk; with water in cats)

Enrofloxacin (5 mg/kg/day, PO) is a suitable alternative to doxycycline.

Treatment of PCR-positive, healthy cats is currently not recommended

Immunosuppressive dosages of glucocorticoids to suppress immune-mediated RBC injury.

Hepatozoonosis

Hepatozoon canis - transmitted by the brown dog tick, Rhipicephalus sanguineus.

North America - H americanum - transmitted by the Gulf Coast tick, Amblyomma maculatum - American Canine Hepatozoonosis (ACH).

Eating paratenic (transport;Ticks) hosts that contain cystozoites - enter the vertebrate host via the gut.

Immunocompetent dogs appear to tolerate infection with H canis very well.

Clinical presentation Depression Muscle atrophy Bloody diarrhea Fluctuating Fever 102.7°–106°F Mucopurulent ocular discharge Severe hyperesthesia or pain over the paraspinal

region is a common finding on physical examination

Dogs maintain a normal appetite if food is placed directly in front of them, but they often will not move to eat, apparently owing to intense pain!

Diagnosis Treatment

Neutrophilic leukocytosis, (WBC = 20,000–200,000 cells/μL).

A mild to moderate normocytic, normochromic, nonregenerative anemia

Platelets - normal to high Mildly increased ALP Radiographs, periosteal

reactions - resemble those of hypertrophic osteoarthropathy

PCR

No known therapeutic regimen completely clears the body of the organism.

TCP = Trimethoprim-sulfadiazine (15 mg/kg, PO, bid) + Clindamycin (10 mg/kg, PO, tid), + Pyrimethamine (0.25 mg/kg/day, PO)

Decoquinate may prevent clinical relapses - 10–20 mg/kg, PO, bid continuously for 2 yr.

 Imidocarb dipropionate twice monthly, @ 5–6 mg/kg, SC

Avoid corticosteroids

Trypanosomiasis

CHAGAS' DISEASE - Trypanosoma cruzi infection more common in dogs.

American trypanosomiasis – zoonotic – vector borne disease - transmitted by Triatomine (nocturnal and hematophagous) ‘kissing’ bugs and caused by T cruzi.

>100 mammalian species (except in Avians!) Dogs (insectivorous by nature) serving as a major

domestic reservoir.

TrypanosomiasisPathology T cruzi maturation occurs in the bloodstreams and anal

odoriferous glands of dogs, and infective trypomastigotes can be shed in feces or urine and ingested.

1. Acute - lymphadenopathy, anorexia, pyrexia, vomiting, diarrhea, and hepatomegaly or splenomegaly and seizures.

2. Chronic phasesa) Latent - generalized weakness or sudden death.b) Symptomatic – Right side-CHF – myocarditis +

arrhythmias + DCM – Death.

TrypanosomiasisDiagnosis Treatment

Routine Peripheral Blood Smear:

Giemsa stain, T cruzi is an extracellular, C-shaped protozoan with a single flagellum.

PCR

T. cruzi - Benznidazole is the drug of choice @ 5–10 mg/kg/day, PO, for 2 months.

Diminazene aceturate @ dose of 3.5 mg/kg in T. congolense infection; 7 mg/kg in T. brucei brucei and T. evansi (Aquinos, 2007)

Quinpyramine sulphate and Allopurinol have also been tried with a moderate success rate – literature insufficient.

THANK YOU