Amyloid deposition in 2 feline thymomas

Two cases of feline thymoma with amyloid deposition were encountered between 1982 and 2010. Neoplastic cells were separated by abundant, pale eosinophilic, homogeneous material that was congophilic and birefringent. Ultrastructurally, the neoplastic cells were connected by desmosomes, and the extracellular deposits were composed of nonbranching, hollow-cored fibrils, 8-10 nm in diameter. In the case with sufficient archived tissue for additional sections, the amyloid remained congophilic following potassium permanganate incubation, and the neoplastic cells were immunoreactive for pancytokeratin. The histologic, histochemical, ultrastructural, and immunohistochemical features of both neoplasms are consistent with epithelial-predominant thymoma with the unusual feature of intratumoral amyloid deposition. The affinity of the amyloid for Congo red following potassium permanganate incubation is consistent with non-AA amyloid. The ultrastructural findings were consistent with amyloid production by the neoplastic epithelial cells.     

Tactical treatment with copper oxide wire particles and symptomatic levamisole treatment using the FAMACHA(©) system in indigenous goats in South Africa

Haemonchosis is considered to be the most economically important gastrointestinal disease of small ruminants in the tropics and subtropics. However, chemical anthelmintics, which were the mainstay of control, have been compromised by a high prevalence of resistance worldwide. Copper oxide wire particles (COWP) have been shown to have anthelmintic effects, but few studies have examined their use under field conditions. The use of COWP was therefore evaluated as a tactical anthelmintic treatment in indigenous goats raised under communal farming conditions in Bergville, KwaZulu-Natal Province, South Africa. At the beginning of the summer rainfall season (October 2007), the faecal egg counts of 172 female goats belonging to 15 farmers were determined and this sampling continued every four weeks until the second week of January 2008. The goats within each of the 15 herds were ranked according to their faecal egg counts for this week. The goats were sequentially paired off within each ranking starting with those goats with the highest counts. One goat from each pair was randomly allocated to a treated or control group. Two weeks later, a 4 g COWP bolus was randomly administered to each goat in the treated group. Faecal egg counts were carried out on the goats two weeks following treatment, and the sampling of the goats then proceeded every four weeks until October 2008. Except for the six-week period prior to the administration of the COWP, the goats were examined according to the FAMACHA^© system and symptomatically treated with 12 mg/kg levamisole when anaemic. The percentage reduction in faecal egg count due to the COWP treatment was 89.0%. Mean pre- and post-treatment faecal egg counts for the COWP-treated group (n = 73) were 2347 eggs per gram of faeces (epg) and 264 epg, respectively. The corresponding values for the untreated controls (n = 66) were 2652 epg and 2709 epg. The prevalence of Haemonchus spp. larvae in pre- and post-treatment faecal cultures was 72% and 46%, respectively. Symptomatic anthelmintic treatments in combination with mid-summer tactical treatments with COWP appear to be useful strategies for the control of Haemonchus contortus in indigenous goats in this farming system and this approach could have application in other similar agro-ecological zones.     

The impact of internal parasites on the productivity of young cattle organically reared on semi-natural pastures in Sweden

A grazing experiment with young cattle was conducted over two consecutive (1997, 1998) grazing seasons on semi-natural pasturelands in central-eastern Sweden. Comparisons were made between groups of animals that were either untreated and set-stocked, ivermectin bolus treated and set-stocked or untreated but moved in mid-summer (mid-July) to ungrazed pasture. The whole experimental area had remained virtually free of cattle during the previous two seasons and the cattle had been raised indoors since birth. To introduce low-levels of parasite infection into the experimental system, each animal received a ‘priming dose’ of approximately 10,000 infective trichostrongylid larvae at the time of turnout for both years. Results of the first year study showed that the level of parasitism was so low that it failed to induce any productivity losses in both groups of untreated cattle, which grew as well as those given boluses at turnout. In contrast, in 1998 both groups of untreated cattle suffered varying degrees of sub-clinical and clinical parasitism to result in an average of 30 kg liveweight depression, compared with the bolus treated cattle, at the end of the season. The only major departure between the two years was that in the latter, the cattle in the untreated groups were exposed to infective larval pickup, which had overwintered on pasture. Cattle in the move treatment grazed in the same sequence on pastures used by similar classes of animals during the previous year. That is, their pastures at turnout had not been grazed since mid-summer of the previous year. Clearly this early season (1997) grazing by young cattle resulted in sufficient overwintered larvae at the start of the following year (1998) to cause productivity losses of the same magnitude as those recorded for young cattle grazing on pastures contaminated for the entire grazing season of the previous year. This was confirmed by tracer tests that were carried out on all treatments, at the time of turnout and the mid-summer move in 1999. These results have major significance to organic cattle producers in Sweden who have a much higher tendency to practice a variety of grazing management techniques aimed at controlling nematode parasite infections in young cattle, than their conventional farming colleagues. It has been identified that one of these strategies is to simply use summer/autumn saved pastures for young stock at turnout, which if grazed by young stock prior to this, could prove to be counter-productive.     

Evaluation of copper supplementation to control Haemonchus contortus infections of sheep in Sweden

A pen study was conducted to assess the effect of providing daily copper mineral supplement, or copper wire particle (COWP) capsules, on established or incoming mixed nematode infections in young sheep. For lambs with established (6 week old) infections, COWP resulted in 97% and 56% reduction of the adult and early L4 stages of H. contortus, respectively, compared with controls (p<0.001). Additionally there was a 74% reduction in Teladorsagia circumcincta infections in the COWP lambs compared with controls (p<0.01). However, no effect was observed when COWP were given at the commencement of a larval dosing period of 6 weeks. There was no significant effect of copper mineral supplement (given at the recommended rate to prevent Cu deficiency) on either established, or developing parasite infections. In addition, a field trial was conducted on a commercial farm to assess the effects of COWP in the management of recurrent H. contortus infections, but lack of parasites during the grazing season prevented an adequate assessment from being made. These results indicate that there is little, if any, benefit from a parasite control standpoint in recommending copper therapy, specifically to control parasites in Swedish sheep flocks.     

Prediction of vitamin A, vitamin E, selenium and zinc status of periparturient dairy cows using blood sampling during the mid dry period

Vitamins A and E, and the trace elements selenium (Se) and zinc (Zn) are essential for the health and performance of dairy cows. Their concentrations often decrease around calving and extra supplementation is sometimes recommended at that time. However, the need for this varies, for example depending on quantity and quality of feedstuffs in the diet. The aim of this study was to measure the concentrations of serum vitamin A (S-vit A) and vitamin E (S-vit E), plasma Se (P-Se) and serum Zn (S-Zn) in blood samples taken at several time points from one month before to one month after calving, and to evaluate if a blood sample taken during the mid dry period can accurately predict the blood concentration at calving and early lactation. Dairy cows on 3 different feeding regimens during the dry period were included in the study. A significant decrease in the concentrations of S-vit A and S-vit E, and S-Zn, was observed at calving, and P-Se was significantly lower during the dry period and at calving than in early lactation. The blood concentrations of S-vit E and P-Se in the mid dry period significantly predicted the occurrence of values considered marginal or deficient at the time of calving. The data indicate that a mid dry period concentration of > or = 5.4 mg/l of S-vit E and > or = 0.09 mg/l of P-Se will result in a 90% chance that the cow stays above marginal levels at calving given that a feed of the same quality is offered.     

Nematophagous fungi as a biological control agent for nematode parasites of small ruminants in Malaysia: a special emphasis on Duddingtonia flagrans

Approximately 2,800 fresh dung samples from animals, mainly ruminant livestock, were screened for the presence of nematophagous fungi in Malaysia. Arthrobotrys spp. was noted on numerous occasions, but only one isolate of Duddingtonia flagrans was made. For the purposes of producing sufficient quantities of this fungus for feeding trials in sheep, various, commonly available, cheap plant materials were tested as possible growth substrates. This showed that cereal grains (wheat, millet and rice) were the best media for fungal growth. Pen feeding trials were carried out using sheep, both naturally and experimentally infected with nematode parasites (predominantely Haemonchus contortus), to test the efficiency of D. flagrans when administered either in a grain supplement, or incorporated into a feed block. These showed that the fungus survived gut passage in sheep and that dose rates of approximately 1 x 10(6) D. flagrans spores / animal / day, reduced the percentage of infective larvae developing in faecal cultures by more than 90%. These results indicate that using D. flagrans as a biological control agent of nematode parasites, is a promising alternative to nematode parasite control of small ruminants in Malaysia, where anthelmintic resistance is now a major problem.