VETERINARY ENTOMOLOGY AND PROTOZOOLOGY COCCIDIA OF DOMESTIC FOWL Eimeria tenella -most pathogenic of avian coccidian -developmental -developmental stages occurs in cecum -sporulation is stimulated by the presence of carbon dioxide and trypsin and bile in the SI -affects frequently birds aged 4 weeks -infection is noticeable at about 72 hours after infection -chicken droops,cease feeding huddle to keep warm -at 96 hours blood appears in droppings Eimeria necatrix -asexual development in SI,gametogony cycle in cecum -lesions are found in the middle third of SI -wall of SI is markedly swollen, hemorrhagic, and the contents filled with unclotted blood Eimeria acervulina -responsible -responsible for subacute or chronic intestinal coccidiosis of older birds and chickens at the point of lay -developmental -developmental stages occur in the anterior part of SI -clinical signs include weight loss and watery whitish diarrhea Eimeria maxima -developmental -developmental stages in SI -SI has marked production of mucus, the mucosa is thickened, there is loss of tone and intestine becomes flaccid and dilated Eimeria mivati -developmental stages in SI but may extend from duodenum to rectum Eimeria mitis -developmental -developmental stages occur in the anterior SI occasionally occasionally in post SI Eimeria brunetti -developmental -developmental stages in SI, cecum, and cloaca -cause severe disease in chicken between 4 th and 9th weeks of age -lesions are confined to the posterior intestine bet the yolk sac and ceca -causes “rectal coccidiosis” Genus Toxoplasma -oocyst with two sporocyst each with four sporozoites -definite hosts are felids
Toxoplasma gondii -definite hosts include domestic cat, jaguarundi, jaguarundi, ocelot, mountain lion, leopard cat, and bobcat. Developmental Developmental cycle Two cycles of development: 1. ente entero roep epit ithe heli lial al 2. extr extrai aint ntes esti tina nall
Enteroepithelial cycle: Occurs in cat and is similar to that of other coccidia consisting of enteroepithelial enteroepithelial multiplicative multiplicative stages and gamonts resulting in oocyst production with sporogony. It is induced by feeding cyst containing bradyzoites( slowly multiplying stages) derived from the brain of mice. Prepatent period is 3-5 days and peak oocyst production occurs from 58 days. Multiplicative stages of Enteroepithelial cycle: 1. Type Type A- appe appear ars s 1212-18 18 hour hours s after after infection, it is the smallest of the multiplicative multiplicative types and is evident as collection of two to three organism in the jejunum. Division is by internal budding 2. Type Type B- occu occurs rs 1212- 54 hour hours s after after infection. It has a centrally located nucleus, a prominent nucleolus and divides by internal budding 3. Type Type C- occu occurs rs 24-5 24-54 4 hours hours after after infection and divides by schizogony. They are elongated and have a subterminal subterminal nucleus. 4. Type Type D- occu occurr from from 32 hour hours s to 15 days days after infection infection and accounts accounts for all 90 % ofToxoplasma in the SI.Divide by internal budding , schizogony and by separation separation of single merozoites from the nuclear mass 5. Type Type E- rese resembl mbles es Type Type D and and occur occurs s 315 days after infection Gamoonts stage: stage : Occurs throughout the SI and aqre common in the ileum 3-15 days after infection Oocyst stage: stage: Oocyst formation occurs in the epithelial cells of SI. Oocysts are discharged from the epithelial cells and shed in to feces. Extraintestinal cycle: These stages are the only forms in the life cycle which occurs in the non-felids. It may also occurs in felid and may start simultaneously
with the enteroepithelial cycle of development in that animal. Tachyzoites formation ( rapidly multiplyinf stages): Seen especially in the visceral infections.Occurs in the lamina propria, mesenteric lymph nodes and distant organs. In other animals animals it begins begins by ingestion of sporulated oocyst. Organism multiply in the by endodyogeny and eventually eventually 8-16 more organisms accumulate accumulate in a host cell which then disintegrates disintegrates and new cells are infected Bradyzoites formation: formation: ( slowly multiplying stage) Contained in cyst are characteristics of chronic infection and occur mainly in the brain, heart and skeletal muscles. Multiply slowly mainly by internal budding. The cyst containing thousands of these forms may persist for months or years after infection. Bradyzoites resist peptic and typtic digestion TOXOPLASMOSIS IN MAN Can be : Congenital-occurs when a woman has 1. Congenital-occurs primary infection during pregnancy. The outcome varies according to fetal damage which in turn depends on the virulence of the strain of organism. In severe infection abortion is common sequel. 2. Acquir Acquireded- suspe suspecte cted d when ther there e is lymphadenopathy, lymphadenopathy, fever, lymphocytosis, meningoencephalitis, meningoencephalitis, eye lesions of doubtful origins or myocarditis. Genus Sarcocystis: Life cycle: Infective sporocysts, derived from the feces of final hosts are ingested. Sporozoites are released in the intestine and they invade many tissues. Schizogony occurs in the endothelial cells of blood vessels in most organs preceding the development of typical cyst in the striated muscles. Two recognizable regions are recognizable recognizable within the cyst. The peripheral region contains globular forms called the metrocytes which by internal budding produce two daughter cells and these after several further replications, give rise to banana shaped bradyzoites. bradyzoites. Infection of the final host is by ingestion of muscle cysts containing bradyzoites. bradyzoites. Schizonts and metrocytes are not infective for the definitive host. Sarcocystis in Cattle: 1. Sarcocystis cruzi cruzi-- most pathogenic species DH- dog, wolves,cayotes,raccoons wolves,cayotes,raccoons,hyenas ,hyenas
-clinical signs includes intermittent pyrexia, reduced milk yield, loss of condition, and difficulty in breathing. 2. Sarcocystis bovifelis- definitive hosts are cat and feral cat. 3. Sarcocystis homonis- definitive hosts are man, rhesus monkey baboon, and not pathogenic in cattle Sarcocystis in Sheep: 1. Sarcocys Sarcocystis tis ovica ovicanisnis- highly highly pathog pathogenic enic for lambs which become anorectic weak and may die. At necropsy the heart is the severely affected organ, schizonts being found in the epithelial cells. 2. Sarcocys Sarcocystis tis tenellatenella- non- pathogeni pathogenic c Sarcocystis of man: 1. Sarc Sarcoc ocys ysti tis s homi homini nis s 2. Sarco Sarcocys cystis tis porcih porcihomi ominis nis * S. hominis and S.porcihominis infection in man is associated with anorexia, nausea and diarrhea 3. Sarcocystis lindemanni- intermediate host is man and final host is unknown Genus Plasmodium: Contains malarial malarial organisms of man and other mammals and vertebrates. Schizogony occurs in the red blood cells and also in the endothelium of inner organs while the sexual phase occurs in blood sucking insects. For mammalian forms these are anopheline mosquitoes and for avian forms culiciline mosquitoes. Avian malaria Species with round or irregular irregular gamonts which displace the nucleus of the host cell 1. Plasmodium cathemeriumcathemerium- transmitted transmitted by several soecies of Culex and Aedes; there is marked enlargement of liver and spleen with anemia and subcutaneous hemorrhages 2. P. gallinaceum- exoerythrocytic stage occurs in the endothelial cells; chicken is particularly susceptible. Birds become progressively emaciated as the disease progresses 3. P. juxtanuclearejuxtanucle are- highly pathogenic especially the Brazilian strain. Chicken becomes listless, weak with anemia and CNS involvement may be seen 4. P. relictum- highly pathogenic for pigeons, 5. P. griffithsiSpecies with elongate gamonts which do not usually displace the host cell nucleus 1. Plasm Plasmodi odium um circum circumfle flexum xum 2. P. durae 3. P. elo elon ngatum tum
4. 5. 6. 7. 8. 9.
P. fallax P. hexa hexame meri rium um P. loph ophura urae P. polare P. rouxi P. vaugh ughani ani
Malarial parasites of man Endogenous developmental cycle -following the bite of infected mosquito, the sporozoites remain in the blood for a short time but after an hour the blood is no longer infective for another host. Sporozoites enter the parenchyma cells of the liver and here develop into preerythrocytic preerythrocytic schizont schizont (cryptozoites). The exoerythrocytic exoerythrocytic forms are confined to the liver in mammalian malaria. The hepatic form grows to become a large schizont, the time for this and the size of the mature form depending on the species of parasite. Following exoerythrocytic development merozoites invade the erythrocytes. Species of the Plasmodia of man 1. Plasmodium falcifarumfalcifarum- the cause of malignant tertian malaria, falciparum malaria or subtertian malaria. There is tendency for the infected rbc to clump. The gamonts are sausage-or cresent shaped and appear in the peripheral peripheral blood. 2. P. malariae- the cause of quartan malaria. The schizont appear in the circulating blood and frequently assume a band across the erythrocytes 3. P. ovale-the cause of mild tertian malaria. A distinctive feature of parasitized rbc is the appearance of Schuffer’s dots, and the cell is fimbriated. This species is present in the Philippines. 4. P. vivax- the cause of benign tertian or vivax malaria which is the most common in the world Genus Babesia Organism multiply in the erythrocytes by asexual division, producing two, four, or more non-pigmented amoeboid parasites. When stained with Romanowsky stain, they show a blue cytoplasm and a red chromatin mass usually at one pole. Babesia of Cattle: 1. Babesia Babesia bigemina bigemina-- cause cause of cattl cattle e tick tick fever, red water fever, piroplasmosis. A large piroplasm and characteristically characteristically pear shaped and lie in pairs forming an acute angle in the red blood corpuscle. Ticks involved: Boophilus annulatus, B. decoloratus, decoloratus, B. microplus, Rhipicephalus evertsi, R. bursa, R. appendiculatus, Haemaphysalis punctata,
2.
Babesia bovis- small piroplasm larger than B. divergens. There is no usually divergent forms lying superficially in the red blood cell and vacuolated signet ring forms are particularly particularly common. Ticks involved: Ixodes ricinus, I. persulcatus, persulcatus, Boophilus calcaratus, calcaratus, B. microplus and R. bursa 3. Babesia Babesia divergen divergenss- small smaller er than than B. bovis bovis and appears as paired, divergent forms lying superficially on the red blood cell. 4. Babesia Babesia majormajor- resem resembles bles B. bigemina bigemina except that it is smaller and lies in the center of the erythrocytes. erythrocytes.
Genus Theleria -organisms multiply schizogony in lymphocytes and finally invade erythrocytes. erythrocytes. Thelaria species of cattle: 1. Thelaria Thelaria parvaparva- cause causes s East East Cost Cost Fever Fever or or bovine theleriasis. Zebu cattle has high natural resistance resistance to it. 2. Thel Thelar aria ia lawr lawren enci ci 3. Thel Thelar aria ia annu annula lata ta 4. Thel Thelar aria ia mut muta ans Thelaria species of sheep: 1. Thelaria Thelaria hircihirci- highl highly y pathoge pathogenic nic to to sheep sheep and goats 2. Thel Thelar aria ia ovis ovis
CLASS KINETOFRAGMINOPHOREA Organism of this class possess cilia for locomotion. They are highly organized form possessing two nuclei, a macronucleus which is large and massive and responsible for the cytoplasmic activities of the organism and a micronucleus concerned with reproductive reproductive process. Reproduction is asexual by transverse transverse binary fission or in sexual phase by conjugation Genus Balantidium: Balantidium : -oval to ellipsoidal in shape in outline, there is distinct macronucleus and small micronucleus. Balantidium coli -widespread in swine and appears as the primary host. Generally Generally it is a commensal of the large intestine Genus Ichthyophthirius -found mainly as parasites of fish in thew gills and skin Ichthyophthirius Ichthyophthirius multifilis- the cause of “ich” or white spot disease and occur in all fresh water fishes. Penetration of the tomite causes severe irritation accompanied accompanied by mucous secretion and hyperplasia hyperplasia of the epithelium
ORDER RICKETSIALLES Genus Anaplasma -appear As small, spherical bodies, red to dark red in color inside the rbc of cattle, deer, sheep and goats. 1. Anaplasma marginale- located at the margin of infected cells 2. Anaplasma centrale- centrally placed in the erythrocyte 3. Anaplasma ovis Anaplasmosis, formerly known as gall sickness, traditionally refers to a disease of ruminants caused by obligate intraerythrocytic intraerythrocytic bacteria of the order Rickettsiales, family Anaplasmataceae, genus Anaplasma genus Anaplasma . Cattle, sheep, goats, buffalo, and some wild ruminants can be infected with the erythrocytic Anaplasma erythrocytic Anaplasma . Anaplasmosis Anaplasmosis occurs in tropical and subtropical regions worldwide (~40° N to 32° S), including South and Central America, the USA, southern Europe, Africa, Asia, and Australia. The Anaplasma The Anaplasma genus has recently been expanded to include species transferred transferred from the genus Ehrlichia , now named Anaplasma named Anaplasma phagocytophilum (compiled from species previously known as Ehrlichia phagocytophila Ehrlichia phagocytophila , E equi , and human granulocytic ehrlichiosis ehrlichiosis agent), A agent), A bovis (previously E bovis ), and A and A platys (previously E platys ), all of which invade blood cells other than erythrocytes of their respective mammalian hosts. Bovine anaplasmosis anaplasmosis is of economic significance in the cattle industry.
Anaplasmosis Anaplasmosis is not contagious. Numerous species of tick vectors ( Boophilus , Dermacentor , Dermacentor , Rhipicephalus , Ixodes , Hyalomma , and Ornithodoros ) can transmit Anaplasma spp . Not all of these are likely significant vectors in the field, and it has been shown that strains of A A marginale also co-evolve with particular tick strains. Boophilus spp are major vectors in Australia and Africa, and Dermacentor spp Dermacentor spp have been incriminated as the main vectors in the USA. After feeding on an infected animal, intrastadial or trans-stadial trans-stadial transmission transmission may occur. Transovarial Transovarial transmission transmission may also occur, although this is rare, even in the single-host Boophilus spp . A replicative cycle occurs in the infected tick. Mechanical Mechanical transmission transmission via biting dipterans occurs in some regions. Transplacental transmission transmission has been reported and is usually associated with acute infection of the dam in the second or third trimester of gestation. Anaplasmosis Anaplasmosis may also be spread through the use of contaminated needles or dehorning or other surgical instruments. instruments. There is a strong correlation between age of cattle and severity of disease. Calves are much more resistant to disease (although not infection) than older cattle. This resistance resistance is not due to colostral antibody from immune dams. In endemic areas where cattle first become infected with A with A marginale early in life, losses due to anaplasmosis anaplasmosis are minimal. After
Etiology:
recovery from the acute phase of infection,
Clinical bovine anaplasmosis is usually caused
cattle remain chronically infected carriers but
by A by A marginale . Cattle are also infected with A with A
are generally immune to further clinical disease.
centrale , which generally results in mild
However, these chronically infected cattle may
disease. A disease. A ovis may cause mild to severe
relapse to anaplasmosis when
disease in sheep, deer, and goats.
immunosuppressed immunosuppressed (eg, by corticosteroids), when infected with other pathogens, or after
Transmission and Epidemiology:
splenectomy. Carriers serve as a reservoir for
(41°C) occurs at about the time of peak
further transmission. Serious losses occur when
rickettsemia. Mucous membranes appear pale
mature cattle with no previous exposure are
and then yellow. Pregnant cows may abort.
moved into endemic areas or when under
Surviving cattle convalesce over several weeks,
endemically unstable situations when
during which hematologic parameters gradually
transmission rates are insufficient to ensure all
return to normal.
cattle are infected before reaching the more
Bos indicus breeds of cattle appear to possess a
susceptible adult age.
greater resistance to A to A marginale infection than B taurus breeds, but variation of resistance of
Clinical Findings: In animals <1 yr old anaplasmosis is usually subclinical, in yearlings and 2 yr olds it is moderately severe, severe, and in older cattle it is severe and often fatal. Anaplasmosis is characterized characterized by progressive anemia due to extravascular extravascular destruction of infected and uninfected erythrocytes. The prepatent period of A A marginale is directly related to the infective dose and typically ranges from 15-36 days (although it may be as long as 100 days). After the prepatent period, peracute (most severe but rare), acute, or chronic anaplasmosis may follow. Rickettsemia approximately doubles every 24 hr during the exponential growth phase. Generally, 10-30% of erythrocytes are infected at peak rickettsemia, although this figure may be as high as 65%. RBC count, PCV, and hemoglobin values are all severely reduced. Macrocytic anemia with circulating reticulocytes may be present late in the disease. Animals with peracute infections succumb within a few hours of the onset of clinical signs. Acutely infected animals lose condition rapidly. Milk production falls. Inappetence, loss of coordination, breathlessness when exerted, and
individuals within breeds of both species occurs. Difference in virulence between Anaplasma between Anaplasma strains and the level and duration of the rickettsemia also play a role in the severity of clinical manifestations. manifestations. Lesions: Lesions are typical of those occurring in animals with anemia due to erythrophagocytosis. erythrophagocytosis. The carcasses carcasses of cattle that die from anaplasmosis anaplasmosis are generally markedly anemic and jaundiced. Blood is thin and watery. The spleen is characteristically enlarged and soft, with prominent follicles. The liver may be mottled and yellow-orange. The gallbladder is often distended and contains thick brown or green bile. Hepatic and mediastinal lymph nodes appear brown. There are serous effusions in body cavities, pulmonary edema, petechial hemorrhages in the epi- and endocardium, endocardium, and often evidence of severe GI stasis. Widespread phagocytosis of erythrocytes is evident on microscopic examination examination of the reticuloendothelial reticuloendothelial organs. A significant proportion of erythrocytes are usually found to be parasitized after death due to acute infection.
a rapid bounding pulse are usually evident in the late stages. The urine may be brown but, in contrast to babesiosis, hemoglobinuria does not
Treatment: Tetracycline antibiotics and imidocarb are
occur. A transient febrile response, with the
currently used for treatment. Cattle may be
body temperature rarely exceeding 106°F
sterilized by treatment with these drugs and
remain immune to severe anaplasmosis subsequently subsequently for at least 8 mo. Prompt administration of tetracycline tetracycline drugs (tetracycline, (tetracycline, chlortetracycline, chlortetracycline, oxytetracycline, oxytetracycline, rolitetracycline, rolitetracycline, doxycycline, minocycline) in the early stages of acute disease (eg, PCV >15%)
midwestern, northeastern, northeastern, and western coastal regions of the USA and in Europe and Asia. The host range of infection and illness for various strains within this genogroup also includes horses and ruminants; dogs and cats may occasionally occasionally be infected. Anaplasma infected. Anaplasma (Ehrlichia) (Ehrlichia) platys is the cause of infectious cyclic thrombocytopenia of dogs. The following discussion of ehrlichiosis primarily describes infection in dogs caused by E canis .
usually ensures survival. A commonly used treatment consists of a single IM injection of
Epidemiology:
long-acting oxytetracycline oxytetracycline at a dosage of 20
E canis and A and A platys platys are enzootic in many parts
mg/kg. Blood transfusion to partially restore the
of the USA and worldwide. These agents are
PCV greatly improves the survival rate of more
transmitted by the brown dog tick,
severely affected cattle. The carrier state may
Rhipicephalus sanguineus . Rhipicephalus ticks
be eliminated by administration of a long-acting
become infected with E canis after feeding on
oxytetracycline oxytetracycline preparation (20 mg/kg, IM, at
infected dogs, and ticks transmit infection to
least 2 injections with a 1-wk interval).
other dogs during blood meals taken in
Withholding periods for tetracyclines apply in
successive life stages. Blood transfusions, transfusions, or
most countries. Injection into the neck muscle
other means by which infected WBC can be
rather than the rump is preferred.
transferred, transferred, may also transmit the pathogens.
Imidocarb is also highly efficacious against A against A
Other Ehrlichia and Anaplasma and Anaplasma species have
marginale as a single injection (as the
sylvan cycles in the environment involving
dihydrochloride dihydrochloride salt at 1.5 mg/kg, SC, or as
various other tick species and wildlife reservoir
imidocarb dipropionate at 3.0 mg/kg).
hosts. In the USA, E chaffeensis and E ewingii
Elimination of the carrier state requires the use
are transmitted by Amblyomma by Amblyomma americanum ,
of higher repeated doses of imidocarb (eg, 5
the lone star tick. Anaplasma tick. Anaplasma phagocytophilum phagocytophilum
mg/kg, IM or SC, 2 injections of the
is transmitted by Ixodes species of ticks; in the
dihydrochloride dihydrochloride salt 2 wk apart). Imidocarb is a
northeastern northeastern USA, infection is transmitted by I
suspected carcinogen with long withholding
scapularis , the black-legged tick, whereas
periods and is not approved for use in the USA
infection in western states is primarily
or Europe.
associated with I pacificus , the Western black-
Genus Ehrlichia: Classical canine monocytic ehrlichiosis is caused by Ehrlichia canis , which infects the mononuclear cells of dogs; canine monocytic ehrlichiosis may also be caused by E chaffeensis , the etiologic agent of human monocytic ehrlichiosis. A monocytic ehrlichiosis has been identified in cats in Africa, France, and the USA; however, the exact species has not been determined. E ewingi is a granulocytic species that has been isolated from dogs and humans in the southern, western, and midwestern USA. Human granulocytic ehrlichiosis, ehrlichiosis, caused by Anaplasma by Anaplasma phagocytophilum is seen in the northern
legged tick. People, dogs, cats, and other domestic animals are incidental hosts of these pathogens. Clinical Findings: In E canis infections, signs arise from the involvement of the hemic and lymphoreticular systems and commonly progress from acute to chronic, depending on the strain of organism and immune status of the host. In acute cases, there is reticuloendothelial reticuloendothelial hyperplasia, fever,
generalized generalized lymphadenopathy, lymphadenopathy, splenomegaly, splenomegaly,
thrombocytopenia may cause epistaxis,
and thrombocytopenia. Variable signs of
hematuria, melena, and petechiae and
anorexia, depression, depression, loss of stamina, stiffness
ecchymoses of the skin. Variably severe
and reluctance to walk, edema of the limbs or
pancytopenia (mature leukopenia,
scrotum, and coughing or dyspnea may occur.
nonregenerative nonregenerative anemia, thrombocytopenia, thrombocytopenia, or
Most acute cases are seen in the warmer
any combination thereof) may occur. Aspiration
months, coincident with the greatest activity of
cytology reveals reactive lymph nodes and,
the tick vector.
usually, marked plasmacytosis. Frequently,
During the acute phase of E of E canis infection in
polyclonal, or occasionally monoclonal,
dogs, the hemogram is usually normal but may
hypergammaglobulinemia hypergammaglobulinemia occurs.
reflect a mild normocytic, normochromic
Dogs infected with A with A platys platys generally show
anemia; leukopenia; or mild leukocytosis.
minimal to no signs of infection despite the
Thrombocytopenia is common, but petechiae
presence of the organism in platelets. The
may not be evident, and platelet decreases may
primary finding is cyclic thrombocytopenia,
be mild in some animals. Vasculitis and immune-
recurring at 10-day intervals. Generally, the
mediated mechanisms induce a
cyclic nature diminishes, and the
thrombocytopenia and hemorrhagic tendencies.
thrombocytopenia becomes mild and slowly
Lymph node aspiration reveals hyperplasia. hyperplasia.
resolves. Other ehrlichial infections not caused
Death is rare during this phase; spontaneous
by E canis appear clinically similar to acute E
recovery may occur, the dog may remain
canis infection, but the clinical course is usually
asymptomatic, or chronic disease may ensue.
more self-limiting. Shifting leg lameness and
Chronic ehrlichiosis caused by E canis may
fever of unknown origin may be present.
develop in any breed, but certain breeds, eg,
Thrombocytopenia and mild leukopenia or
German Shepherds, may be predisposed.
leukocytosis may occur during the acute course
Seasonality Seasonality is not a specific hallmark of chronic
of infection, which is clinically more discrete.
infection, as appearance of chronic signs may be
Chronic disease, as seen with E canis infection,
variably delayed following acute infection. In
is not typically seen in other ehrlichial infections.
chronic cases, the bone marrow becomes
Lesions:
hypoplastic, and lymphocytes and plasmacytes
During the acute or self-limiting phase of E of E canis
infiltrate various organs. Clinical findings vary
infections, lesions generally are nonspecific, but
based on the predominant organs affected, and
splenomegaly splenomegaly is common. Histologically, there is
may include marked splenomegaly,
lymphoreticular lymphoreticular hyperplasia, hyperplasia, and lymphocytic
glomerulonephritis, glomerulonephritis, renal failure, interstitial
and plasmacytic perivascular cuffing. In chronic
pneumonitis, anterior uveitis, and meningitis
cases, these lesions may be accompanied by
with associated cerebellar ataxia, depression,
widespread hemorrhage and increased
paresis, and hyperesthesia. Severe weight loss is
mononuclear cell infiltration in perivascular perivascular
a prominent finding.
regions of many organs.
The hemogram is usually markedly abnormal in chronic cases. Frequently, severe
Treatment: The drug of choice for all forms of infection
caused by these organisms is doxycycline because of its superior intracellular intracellular penetration. The recommended dosage is 5-10 mg/kg, PO or IV,
SID
for 10-21 days. Tetracycline Tetracycline (22 mg/kg,
PO, TID) can also be used for ≥2 wk in acute cases and 1-2 mo in chronic cases. Two doses of imidocarb dipropionate dipropionate (5-7 mg/kg, IM), 2 wk apart, are variably effective against both ehrlichiosis and some strains of babesiosis. In acute cases receiving appropriate appropriate antibiotic therapy, body temperature is expected to return to normal within 24-48 hr after treatment. In chronic cases, the hematologic abnormalities abnormalities may persist for 3-6 mo, although clinical response to treatment often occurs much sooner. Supportive therapy may be necessary to combat wasting and specific organ dysfunction; platelet or whole-blood transfusions may be required if hemorrhage is extensive. Concurrent broad-spectrum broad-spectrum antibiotics may be needed if the dog has severe leukopenia. The E canis antibody titer should be measured again within 6 mo of illness to confirm a low or seronegative status indicative indicative of successful therapy. Serum titers that persist at lower but positive levels should be rechecked in another 6 mo to ensure that they are not increasing.
