Morphologic alteration of Anaplasma marginale in calves treated with a dithiosemicarbazone.

Blood and clotted blood samples from 3 calves with anaplasmosis were examined by light and electron microscopies before and after the calves were treated twice with alpha-ethoxyethylglyoxal dithiosemicarbazone (given IV). In the treated calves anaplasma bodies were swollen and irregularly shaped and had rough surfaces when viewed by light microscopy. Posttreatment electron microscopic examinations revealed swelling and vacuolation of initial bodies of anaplasma bodies, and ballooning of the vesicular membrane surrounding the anaplasma body. Other initial bodies were ameboid in shape this was or was not accompanied by rupture of the vesicular membrane of the anaplasma body. Necrotic, ameboid-shaped initial bodies also were seen. Some necrotic initial bodies were surrounded by complete vesicular membrane, and others were close to a broken, curled vesicular membrane.

Experimental Naegleria fowleri meningoencephalitis in sheep: light and electron microscopic studies.

A sheep infected intranasally with Naegleria fowleri of human origin died 7 days after inoculation. The olfactory lobes were distinctly soft and friable. Histologic findings indicated suppurative leptomeningitis and hemorrhagic necrosis in the olfactory lobes. Protozoa were disseminated in the necrotic areas, particularly in perivascular locations; vasculitis was also observed. Meningitis and perivascular cuffing with lymphocytes were evident in the cerebrum, cerebellum, pons, medulla, and cervical spinal cord. Electron microscopy disclosed trophozoites only in the olfactory lobes. The amebae contained a central nucleus with a distinct, electron-dense nucleolus. The cytoplasm contained myelinated figures, lipid-like vacuoles, open vesicles, electron-dense granules, mitochondria, numerous free ribosomes, scant rough endoplasmic reticulum, and occasionally a phagocytized erythrocyte. Trophozoites were grouped close to arterioles, except when phagocytized by a neutrophil or endothelial cell.

Experimental infection of sheep with Naegleria fowleri of human origin.

A strain of Naegleria fowleri, isolated from a child who died of primary amebic meningoencephalitis in Florida, was instilled in the nostrils of a sheep to determine whether livestock are susceptible to infection with free-living amebae. The animal died 7 days later from amebic infection of the central nervous system. N. fowleri were recovered from the brain and spinal cord of the animal. A control, saline-instilled sheep that had been pair-caged with the infected animal remained healthy.

Ultrastructure of Babesia equi in ponies treated with imidocarb.

Four splenectomized ponies were infected with Babesia equi. Two ponies were not treated, and two were treated with 5 mg of imidocarb/kg of body weight when 20% of their erythrocytes were parasitized. The nucleus of the parasite in erythrocytes from blood smears of nontreated ponies was roundish, deep red-staining, and usually composed two-thirds of the organism. The parasite in erythrocytes from blood smears of treated ponies was swollen and vacuolated except for an area just beneath the plasma membrane where the compressed nucleus was marginated, elongated, and clumpy. Parasites in erythrocytes from nontreated and treated ponies were examined by electron microscopy. Babesia equi in erythrocytes of nontreated ponies contained food vacuoles, a prominent nucleus, smooth and rough endoplasmic reticulums, and ribosomes. There were four stages of degeneration of B equi in erythrocytes of ponies treated with imidocarb. The first stage was dilatation of the nuclear cisterna and clumping of chromatin. The second stage included dissolution of the nuclear envelope and passage of nuclear matrix into the cytoplasm. The third stage consisted of vacuolation of the cytoplasm and compression of the chromatin to the periphery of the cell. In the fourth stage of degeneration, the organism consisted essentially of a vacuole, and chromatin was condensed into an irregular mass of clumped material.

Induction of lactation: lactational, physiological, and hormonal responses in the bovine.

Milk yields, physiological responses, and concentrations of plasma hormones were evaluated in 24 attempts to induce lactation in nonlactating dairy cows. Subcutaneous injections of estradiol-17beta and progesterone (.10 and .25 mg/kg body weight per day) for 7 consecutive days were used. Dexamethasone injections (.028 mg/kg body weight per day) on days 18 to 20 were given during 12 attempts at induction. Milking was initiated on day 21. All cows showed proestrus activity within 2 days after the first steroid injection; this subsided, then reappeared in many animals between days 16 to 20. In 14 of 24 attempts mean daily milk production was greater than 5 kg. Actual or projected 305-day lactation milk yields were between 1859 and 5354 kg. However, milk yields of seven induced cows averaged only 73% (32% to 136% range) of their previous natural lactations. Dexamethasone injections increased the number of cows that produced more than 5 kg/day; however, milk yields were not improved. Concentrations of estradiol, estrone, and progesterone in plasma were unaffected by dexamethasone, but concentrations of glucocorticoids in plasma were depressed on days 19 to 22. Concentrations of prolactin (peak and mean) in plasma for six cows each that produced greater or less than 5 kg/day did not differ. However, concentrations of prolactin increased in the week following steroid injections (days 8 to 15) only in those cows that produced greater than 5 kg/day but were elevated in all cows during the 3rd wk.

Equine antibody to bovine serum induced by several equine vaccines as a source of extraneous precipitin lines in the agar gel immunodiffusion test for equine infectious anemia.

Precipitin lines not associated with equine infectious anemia (EIA) were observed in routine agar gel immunodiffusion (AGID) testing for the infection. The serums which produced these lines were obtained from horses which had been given multiple vaccinations with commercially available cell culture-origin equine virus vaccines as part of a comprehensive herd health program. The lines formed against cell culture-derived, but not spleen-derived EIA viral antigens. Investigation revealed that bovine serum proteins in the vaccines induced precipitating antibodies which reacted with bovine serum proteins in cell culture-derived antigens. A vaccination trial, utilizing 4 commercially available vaccines in various combinations, indicated that as few as 2 vaccinations could induce AGID-detectable antibodies to bovine serum proteins in individual ponies. These antibodies were very transitory, usually lasting no longer than a week. Some horses, however, which had been given 4 vaccinations developed similar antibodies which persisted 3 months beyond the last vaccination. The extraneous precipitin lines produced by these antibodies in the AGID test for EIA were readily distinguished from true EIA-associated reactions and did not result in false-positive interpretations of the test. However, heavy percipitin lines due to strong antibovine serum activity did mask weakly positive EIA reactions.