Ticks of Veterinary Importance Ixodidae sclerotized dorsal shield – “hard ticks” sexually dimorphic – females larger – male scutum covers dorsum Argasidae unsclerotized – “soft ticks” little sexual dimorphism
Ticks of Veterinary Importance Ixodidae primarily off host – “sit-and-wait” mate on host require days to complete engorgement live outdoors Argasidae live in close proximity to host mate off host require mins - hrs to feed and feed repeatedly live in dwelling/sleeping places of hosts
Tick Pathogenesis anemia – heavy infestations
Tick Pathogenesis anemia dermatosis – inflammation, swelling, itching, ulceration from tick’s saliva and mouthparts
Tick Pathogenesis anemia dermatosis paralysis – neurotoxin present in saliva of some species Dermacentor sp.
clinical signs...in dogs fever, anorexia, malaise lymphadenomegaly shifting leg lameness – sudden onset painful articular swelling *nonerosive polyarthritis – pathologic changes in the joints are progressive rarely: renal disease (glomerulonephritis), neurological disease
diagnosis clinical lab findings – inflammatory changes in synovial fluid serology – ELISA detects antibodies to B. burgdorferi Isolation – culture is most definitive...but also most difficult due to limited number of organisms present – PCR
antibiotic therapy – for arthritis: doxycycline, amoxicillin, azithromycin – for neurological manifestations: cefotaxime, chloramphenicol vaccines treatment
Hepatozoonosis...a closer look etiologic agent: – Hepatozoon canis...an intracellular parasite in various tissues – transmitted via ingestion of infected tick (Rhipicephalus sanguineous)
dog ingests tick
sporozoites in GI tractcirculationstriated muscle
“onion skin” cyst in skeletal muscle dog ingests tick sporozoites in GI tractcirculationstriated muscle
“onion skin” cyst in skeletal muscle ~ 4 weeks...parasite infected neutrophils (gamonts) present in peripheral blood dog ingests tick sporozoites in GI tractcirculationstriated muscle asexual reprod. (merogony) merozoites released into surrounding tissues severe inflamm. reaction neutrophilic granuloma formation
Hepatozoonosis...a closer look etiologic agent: – Hepatozoon canis...an intracellular parasite in various tissues – transmitted via ingestion of infected tick (Rhipicephalus sanguineous) clinical signs: – fever, anorexia, weight loss, diarrhea...wax and wane diagnosis: – CBC, Biochem.: non-specific inflammation – UA: +/- proteinuria – muscle biopsy for definitive diagnosis treatment: – symptomatic: NSAIDs
Hepatozoonosis via radiology? Periosteal proliferation on the femur, tibia, pelvis and lumbar vertebrae of a dog infected with H. canis
Hepatozoonosis via radiology? Periosteal proliferation on the femur, tibia, pelvis and lumbar vertebrae of a dog infected with H. canis...lesions resemble HO
Periosteal proliferation on the femur of a dog infected with H. canis Hepatozoonosis via radiology?
Hepatozoonosis via Bone Scan Skeletal lesions in a dog infected with H. canis (americanum)
References Craig, T.M Hepatozoonosis, pp , In: Infectious Diseases of the Dog and Cat, 2 nd Edition; Craig E. Greene (Ed), W.B. Saunders, Pennsylvania. Greiner, E.C Diagnosis of arthropod parasites, pp , In: Veterinary Clinical Parasitology, 7 th Edition; Anne M. Zajak and Gary A. Conboy (Eds), Blackwell Publishing, Iowa. Holman, P.J., and K.F. Snowden Canine hepatozoonosis and babesiosis, and feline cytauxzoonosis. Vet Clin Small Anim 39: Little, S.E Vector-borne diseases, pp , In: Georgis’ Parasitology for Veterinarians, 9 th Edition; Dwight D. Bowman (Ed), Saunders Publishing, Missouri. Panciera, R.J., Mathew, J.S., Ewing, S.A., Cummings, C.A., Drost, W.T., and A.A. Kocan Skeletal lesions of canine hepatozoonosis caused by Hepatozoon americanum. Vet Pathol 37: Shaw, D. and S. Ihle Joint diseases, pp , In: Small Animal Internal Medicine; Shaw, D. and S. Ihle (Eds), Blackwell Publishing, Iowa.