The activity of ivermectin against common nematode parasites of sheep was examined in 2 experiments. In the 1st experiment, 14 sheep with naturally acquired infections were assigned to 2 groups of 7 sheep each. Sheep in 1 group were treated with 200 micrograms of ivermectin/kg of body weight and the remainder served as nontreated controls. In the 2nd experiment, 15 sheep with experimentally supplemented infections (including a benzimidazole-resistant strain of Haemonchus contortus) were assigned to 3 groups of 5 each. The 1st group was treated with 200 micrograms of ivermectin/kg, the 2nd was treated with 88 mg of thiabendazole/kg, and the 3rd served as nontreated controls. Ten to 12 days after treatment, all sheep were euthanatized and necropsied, and the parasites they harbored were recovered and identified. Efficacy of ivermectin was excellent (greater than 96%) against Dictyocaulus filaria, H contortus, Ostertagia circumcinta, Marshallagia marshalli, Trichostrongylus axei, T colubriformis, and T vitrinus. Treatment was not as uniformly effective for Nematodirus spathiger (73% to 85%), N filicollis (80% to 96%), Cooperia curticei (92% to 100%), immature nematodes (92% to 100%), and early 4th-stage larvae (46% to 100%). Efficacy of thiabendazole was poor for H contortus (42%) and early 4th-stage larvae in the abomasum (52%), but approached 100% for most of the other parasites.

Parafilaria bovicola in naturally and experimentally infected calves, pathological changes, comparison of lesions found during the pre-patent period with those found during patency, with object of estimating age of lesions by their macroscopic and microscopic appearance

Dermacentor andersoni, transmission of Anaplasma marginale to splenectomized calves by injection of gut homogenates from incubated vs. non-incubated adult ticks

Parafilaria bovicola, cattle, epizootiology, results of questionnaire survey among cattle owners revealed that (i) condemnation losses due to parasite were overrepresented among animals that came from herds held on pasture the previous year, as opposed to those from farms with indoor cattle management only; (ii) statistically significant difference between affected and nonaffected herds with respect to age groups; and (iii) frequency of lesions showed seasonal trend: Sweden

Haematobia thirouxi potans, two methods described for laboratory rearing, adult flies can be fed either on a bovine calf or on bovine blood in vitro

Eimeria tenella, chickens (exper.), alpha-difluoromethylornithine promising for preventive chemotherapy, perhaps prevents schizont formation, anticoccidial effect possibly due to inhibition of putrescine biosynthesis; immunity to reinfection after treatment

Strongylus vulgaris (larvae), Trichostrongylus axei (adults), ponies (exper.), efficacy of ivermectin, controlled tests