Infectious diseases are transmitted to the dog cat

Treatment of cats with cytauxzoonosis.

these drugs are used in cats at lower doses than those

usually recommended in dogs for the treatment of

babesiosis, and both may transiently worsen the clinical

status of the recipient. Early administration of

subcutaneous heparin, together with fluid therapy and

blood transfusions, may also be beneficial in the

management of DIC, but controlled studies are lacking.

Zoonotic potential/public health significance

There is currently no recognized zoonotic potential of C. felis infection.

Babesiosis and cytauxzoonosis

Treatment of cats with cytauxzoonosis.

Type of therapy Drug/medication Recommended dose Frequency

Notes/comments Specific

Diminazine aceturate

2 mg/kg i/m Once Imidocarb dipropionate

2 mg/kg Ii/m Repeat after 3–7 days

Haemolysis and icterus may worsen

transiently after injection

Anticholinergic signs (vomiting,

diarrhoea, miosis, 3rd eyelid prolapse

and muscle fasciculations) controlled

by atropine (0.05 mg/kg s/c) Crystalloid fluid

therapy To correct dehydration and provide maintenance Refer to Table 17

Ongoing Care to avoid excess haemodilution

As required Blood typing or cross-match is necessary to ascertain compatibility of donor blood

Reduce dose gradually to avoid rebound hypercoagulability Supportive

Blood transfusion Heparin

100–150 units/kg s/c q8h 77

Hepatozoonosis

Gad Baneth and Nancy Vincent-Johnson

CANINE HEPATOZOONOSIS

Background, aetiology and epidemiology

Canine hepatozoonosis is a tick-borne disease caused by

apicomplexan protozoa from the family Hepatozoidae.

Two distinct species of Hepatozoon are known to infect

dogs: Hepatozoon canis and Hepatozoon americanum.

H. canis infection (HCI) was first reported from India

in 1905 and has since been described in southern Europe,

the Middle East, Africa, southeast Asia and South

America (68). H. canis infects the haemolymphatic tissues

and causes anaemia and lethargy. H. americanum

infection (HAI) is an emerging disease in the USA that is

spreading north and east from Texas, where it was

originally detected in 1978. This organism infects

primarily muscular tissues and induces severe myositis

and lameness. H. americanum was initially considered a

strain of H. canis, until it was described as a separate

species in 1997. The species distinction was based on

differences in the clinical disease manifestations, tissue

tropism,

pathological

characteristics,

parasite

morphology and tick vectors. Subsequent genetic and

antigenic comparative studies have supported the separate

species classification (Table 19).

The main vector of H. canis is the brown dog tick

Rhipicephalus sanguineus, which is found in warm and

temperate regions all over the world. The Gulf Coast tick

Amblyomma maculatum is the vector of H. americanum.

A. maculatum exists in the southern part of Nort

68 Reported geographical

distributions of H. canis and

H. americanum.

Hepatozoon canis

Hepatozoon americanum

America, throughout Central America and in the northern

part of South America. In the USA, A. maculatum was

once confined to the warm, humid regions along the Gulf

and South Atlantic coasts but recently its geographic

range has expanded to reach as far inland as southern

Kansas and Kentucky. Both of the Hepatozoon species

that infect dogs are transmitted trans-stadially from the

nymph to the adult stage in their tick vectors. Larval

A. maculatum ticks can also become infected and transmit H. americanum as newly moulted nymphs or adults.

Whereas H. canis appears to be a parasite of canines

that is well adapted to dogs, and causes only mild clinical

signs in the majority of infections, it seems that

H. americanum is less adapted to parasitic co-existence in

the dog, causing a severe disease in most cases. It is

possibly a parasite of some other animal in North America

and is transmitted to dogs through ingestion of ticks that

feed as nymphs or larvae on the natural host. Gamonts

and meronts of a Hepatozoon species have been reported

in coyotes, bobcats and ocelots in the USA. The majority

of these animals were in good physical condition at the

time of capture. H. americanum has been successfully

transmitted to coyote puppies from A. maculatum ticks

that had previously fed on infected dogs. In contrast to the

infected adult animals, puppies developed clinical signs of

myasthenia, pain, ocular discharge, leucocytosis and

inappetence. They also developed bone lesions typically

seen in dogs with HAI and one pup was infective to

nymphal A. maculatum ticks.

Hepatozoonosis

Table 19 Comparison of Hepatozoon americanum and Hepatozoon canis infections.

Organism

H. americanum

H. canis

Main clinical signs

Lameness

Muscular hyperaesthesia

Fluctuating fever

Lethargy