ETIOLOGY: It is a disease caused by a protozoan called Hepatozoon canis that is transmitted by ticks of the genus Rhipicephalus sanguineus with transestadial transmission. Parasite macrophages and endothelial cells of body tissues after their entry by intestinal route after the intake of a tick contaminated with Hepatozoon oocysts. The pathogenesis of this disease is complex and so far unclear. It seems that the simultaneous presence of another infection or immunosuppression states is necessary to manifest. The lesions are from vasculitis and by the presence of immunocomplexes.
FORECAST: The prognosis is reserved, since there is no effective treatment although there are temporary and permanent improvements.
SYMPTOM: They are serious systemic signs such as persistent intermittent fever, weight loss, diarrhea, anorexia, depression, generalized pain, ocular-nasal suppuration, paresis and subsequent paralysis. The clinical signs appear and disappear cyclically. On many occasions it is difficult to discern which disease is causing the clinical signs, since it is frequently associated with other diseases such as ehrlichiosis, leishmaniosis and distemper.
TREATMENT: It is accepted that there is no effective treatment to eliminate the parasite from the host, although remission of clinical signs can be obtained using trimetropin-sulfa (15 mg / kg / 12 h), pyrimethamine (0.25 mg / kg / 24 h) and clindamycin (10 mg / kg / 8 h) for 14 days. Although the response to taratmiento is usually good, most dogs have relapses again after 2-6 months of taratmiento. Since many dogs suffer from other tick-borne diseases in addition to Hepatozoon, the combination of [doxycycline] and imidocarb dipropionate can also be used. A symptomatic treatment of pain with [AAS], [naproxen] or magnesium metamizol can be used.
Study of 50 cases of hepatozoonosis in naturally infected canines in Greater Buenos Aires, Argentina.
Vet. Arg. - Vol. XXIX - Nº 293 - September 2012.
Pérez Tort, G *., Petetta, L. *
The objective of this report is the description of the clinical signs presented by 50 canines affected by Hepatozoon canis who attended the Veterinary Hospital of Virreyes between 2007 and 2008.
Keywords: canines, Hepatozoon canis, clinical signs.
Description of 50 cases of canine hepatozoonosis in dogs naturally infected in Great Buenos Aires, Argentina.
Abstract: The objective of this report is the clinical description of 50 dogs naturally infected with Hepatozoon canis.
Key words: dogs Hepatozoon canis, clinical signs.
* Faculty of Veterinary Sciences of the University of Buenos Aires.
Virreyes Veterinary Hospital Access North 2502, San Fernando.Prov. Buenos Aires, Argentina.
Hepatozoonosis is a disease that has become widespread in recent years. Hepatozoon spp. It is a protozoan of the phylum Apicomplexa, which parasites the white blood cells of dogs. Its transmission occurs by ingestion of ticks containing sporulated oocysts. Currently two species of Hepatozoon: H. canis is transmitted by Rhipicephalus sanguineus Y H. americanum by Amblyoma maculatum. He H. americanum It is much more pathogenic and can be lethal. Between H. canis and H. americanum there are differences in morphology, pathogenic action, tropism by different tissues, and clinical signs. In Argentina we have H. canis, which is less pathogenic, and usually requires the simultaneous presence of another infectious, parasitic (eg toxoplasmosis) or traumatic disease in order to accentuate the clinical signs. The dog becomes infected when it ingests a tick that contains sporulated oocysts. Sporozoites are released in the digestive tract of the dog, penetrate the wall of the intestine and are transported by blood or lymph to the liver, lymph nodes, kidneys, bone marrow and muscle where schizogonia occurs. Numerous merozoites are produced, some of them enter neutrophils and monocytes and become gametocytes. By sucking a dog's blood a tick ingests an amount of blood with gametocytes that are released into the intestine of the tick. The gametogonia takes place and the union of the microgameto and microgameto, a mobile zygote is formed that is directed to the hemocele of the tick, the sporulation of the oocysts that evolve until they become infectious takes place, sporulated oocysts, that is, with sporozoites, that is, infective, in the tick cavity and the cycle continues. The presumptive diagnosis is guided by the history: contact with ticks is essential. The history report "had ticks" to look for the presence of hemoparasite symptoms and signs: hyperthermia, anemia, polydipsia, polyuria, motor disorders of the posterior limbs, prostration. Radiographs: Periodic formation of new bone possibly resulting from inflammation of the muscle near the insertion points. Osteopathy is represented by diaphyseal periodic proliferation. These lesions occur more in young animals. Laboratory findings in Hepatozoonosis: proteinuria, anemia, leukocytosis (this finding is very frequent), increased FAS. The diagnostic certainty is achieved by visualization of the schizont in different organs and tissues by histopathology or imprints of organs) but above all by the finding of gametocytes in white blood cells. These can be observed from day 28 post infection although there are cases in which they do not appear until 40 days post infection. The percentage of parasitization is very variable (from 0.5 to 90%) so it is recommended to review 500 GB. Blood is drawn from veins or from the cephalic or saphenous smear is performed immediately or it can be collected in a microhematocrit tube in such a way as to perform a concentration of GB.to facilitate the visualization of gametocytes. It is not convenient to refrigerate the blood. Smears can be colored by different techniques: May Grunwald, Giemsa or with Giemsa or with T 15. Hepatozoon It may be a mere finding or responsible for a severe illness. The objective of this work is the report of the clinical aspects of canine hepatozoonosis in the Greater Buenos Aires area, Argentina.
Materials and methods.
Fifty animals that were admitted to the Veterinary Hospital of Virreyes during 2007 and 2008 were taken by their owners to a veterinary control, who presented or not clinical signs of the disease that had or had had ticks for more than 20 days (direct observation and count) , owners were questioned about the presence of ticks in the past, with the presence of Hepatozooncanis in your blood tests.
Experimental design: 1 ml of blood was taken with EDTA from the antebrachial cephalic vein or external saphenous vein using a 0.80x 2.5 needle. A colored smear was performed as described in Introduction, reviewing 500 white blood cells to determine the percentage of parasitization, the general and particular objective examination of the patients was performed. Patients with claudication of one or more members had radiographic plaques. Data were entered in one form per dog.
22 males and 28 females, aged between 2 months and 17 years, belonging to various races and also undefined were included in this study. The presence or absence of ticks was found: they were found Rhipicephalus sanguineus more than 50 per animal in 28 canines, less than 50 ticks in 3 of them. When the owners were questioned about the presence of ticks, the owners mentioned the presence of ticks in 13 animals, the owners said they were unaware of contact with ticks: in 6 animals. The concomitant pathologies of the canines were the following: Gastroenteritis: 6 dogs, Distemper: 8 dogs, Suppurative balanoposthitis: 1, Sarcoptic mange: 2 poor care for malnutrition: 1, Urinary infection: 4, TVT: 1 pyoderma: 2, prostate tumor: 1, pulmonary metastasis: 1, intestinal parasitosis with clinical signs due to Ancylostoma caninum: 3, without other concomitant diseases: 20. The number of canines affected by the following signs were: Anemia 26, weight loss: 17, anorexia 14, weakness 13, depression 9 fever: muscle pain 5, periostitis 2, no signs: 8 , lymphadenopathy 4, neurological signs 2, hepatomegaly 1, splenomegaly 1. Percentages of presence of gamontes in blood: from 0.10% to 52% of phagocytes in all animals.
Discussion: It is noteworthy that unlike other publications on this disease in 42 animals there were clinical signs, even in adult animals, that is to say Hepatozoon canis It has been pathogenic for 42 of the 50 dogs that we included in this study, 20 of which had no associated disease. These findings suggest that we could have a pathogenic strain of Hepatozoon canis able to produce per se signs of illness
The clinical findings are consistent with those of the literature consulted but it is noteworthy the presence of clinical signs in the absence of concomitant diseases, although asymptomatic carriers were found. The frequency of occurrence of Hepatozoon canis in the canines of Greater Buenos Aires, it is associated with strong parasitization Rhipicephalus sanguineus and it is one more argument to fight against this ectoparasitosis.
Dogs with signs of hepatozoonosis.
Hepatozoon canines in blood, at higher magnification. Javier Mas photo