Diminazene aceturate is one of a limited number of drugs currently being used in animals to treat the tsetse fly-transmitted protozoal disease, African trypanosomiasis. Efficacy of the drug at the recommended single IM administered doses of 3.5 and 7.0 mg/kg of body weight is widely acknowledged. However, resistance to the drug at these dosages has been reported. Although the mechanisms of resistance to diminazene are poorly understood, field and experimental data indicate that it may develop naturally through administration of subcurative doses, or as a result of cross-resistance. Evidence from other experimental studies indicates that there are additional mechanisms by which trypanosomes may develop resistance to diminazene aceturate. For instance, some populations ot Trypanosoma brucei and T. vivax are refractory to treatment because of their ability to invade the CNS, a site that is believed to be poorly accessible to diminazene. Furthermore, in recent studies carried out in goats, it has been documented that the ability of T. Congolense IL 3274 to survive treatment with diminazene depends on the stage of infection when treatment is administered; populations of the parasite reappeared in animals that were treated on day 19 after tsetse fly challenge, whereas all goats were cured when treated on day 1 of infection. Because trypanosomes are confined to the skin on day 1 after infection, but thereafter invade the blood circulation, it is possible that the efficacy of the treatment on day 1 is attributable to exposure of the small number of parasites, relative to later stages of infection, to higher concentrations of drug than those attained in blood. The objective of the study reported here was to determine whether diminazene's pharmacokinetics differ between plasma and lymph draining the skin of goats and therefore account for the variation in therapeutic activity of the drug at different stages of a tsetse fly-transmitted infection. Peripheral lymph was used for this work because it appears to be identical in composition to tissue interstitial fluid, into which trypanosomes are inoculated by infected tsetse flies when feeding.

Diarrhoea in growing-finishing pigs is a common problem of commercial pig farms. Among many causative factors, porcine circovirus type 2 (PCV2) is one considered an important pathogen in modern pig production. The aim of the study was to verify if PCV2 was responsible for antibiotic non-responsive diarrhoea and wasting in pigs. A total of 13 dead pigs aged between 12 and 15 weeks from three Polish farms with persistent herd symptoms suggestive of PCV2 infection were provided for evaluation. Sections of lymph nodes and intestines were analysed by in situ hybridization (ISH) for PCV2 and histopathological examination. Faeces and intestinal scrapings were tested for Lawsonia intracellularis and Brachyspira hyodysenteriae by real-time PCR and for parasitic infection by flotation and decantation. ISH and histopathological examination showed that all pigs were PCV2 systemic disease negative. Swine dysentery was confirmed by real-time PCR on two farms, and proliferative enteropathy on one farm. In histological examinations, erosions of the caecal and colonic mucosa were found, together with cysts and trophozoites of Balantidium coli. The protozoa were present in the intestinal lumen and mucosa. B. coli cysts were identified in faeces from all examined pigs. These results suggest that monitoring of B. coli infections should be an additional measure of control and prevention of gastrointestinal tract disorders in modern swine husbandry.

Integrin alpha-v/beta3 (αvβ3) recognizes arginine-glycine-aspartic acid (RGD) sequences and has important functions in cell adhesion, signaling, and survival. However, the expression of integrin αvβ3 in the equine lungs and jejunum is not well understood. The objective of this study was to explore the hitherto unknown expression of integrin αvβ3 in the lungs and jejuna of the horse using light and electron immunocytochemistry. Immunohistochemistry showed integrin αvβ3 on the epithelium, the immune cells in Peyer's patches, the smooth muscle, and the endothelium of equine jejuna. In equine lungs, we recognized integrin αvβ3 on the endothelium of blood vessels, the alveolar septa, the bronchial lymph nodes, and the cartilages, although the expression of integrin αvβ3 was weak on the epithelium of bronchioles. In conclusion, these are the first data to show the expression of integrin αvβ3 in equine lungs and jejuna.

Starling forces and hemodynamics in the digits of 5 horses were studied during early laminitis induced by oral administration of an aqueous extract of black walnut (Juglans nigra). The black walnut extract was prepared from heartwood shavings and was administered by nasogastric tube. Heart and respiratory rates, rectal temperature, central venous and arterial pressures, digital pulses, and signs of lameness were monitored. Blood samples were collected for determination of WBC count, hemoglobin concentration, and PCV and for endotoxin and tumor necrosis factor assays. Total WBC count and central venous pressure were monitored until they decreased by 30 or 20%, respectively. These decreases in WBC count and central venous pressure were observed 2 to 3 hours after dosing with black walnut extract. Respiratory and heart rates, body temperature, systolic and diastolic blood pressures, PCV, and hemoglobin concentration did not change significantly. Anesthesia was induced, heparin (500 IU/kg of body weight) was administered IV, and a pump-perfused extracorporeal digital preparation was established. Digital arterial and venous pressures were maintained at 100 and 30 mm of Hg, respectively. Blood flow, capillary pressure, lymph and plasma protein concentrations, and weight of the isolated digit during rapid increase in venous pressure were measured. Isogravimetric capillary filtration coefficient, vascular compliance, vascular and tissue oncotic pressures, tissue pressure, osmotic reflection coefficient, and precapillary and postcapillary resistances were calculated. Mean digital blood flow was 14 ml/min/100 g, capillary pressure was 52 mm of Hg, and vascular compliance was 0.06 ml/mm of Hg. The vascular and tissue oncotic pressures were 21.49 and 4.93 mm of Hg, respectively. The osmotic reflection coefficient was 0.71, and tissue pressure was 41 mm of Hg. The precapillary and postcapillary resistances were 7 and 2 mm of Hg/ml, respectively. Capillary permeability to proteins was not significantly different from that previously measured in healthy horses, suggesting that the increased capillary filtration coefficient reflected increased capillary hydrostatic pressure and perfusion of previously nonperfused capillaries. Neither endotoxin nor serum tumor necrosis factor activity was detected in any samples. The hemodynamic and Starling forces observed in this study were similar to those observed after laminitis was induced by administration of a carbohydrate gruel. Significant differences between the 2 models were detected for total vascular resistance, postcapillary resistance, and capillary filtration coefficient. It is likely that these differences were identified because the horses administered the black walnut extract were at an earlier stage in the disease process. The findings of this study suggest that the increase in capillary pressure causes transvascular fluid movement, resulting in increased tissue pressure and edema. We hypothesize that further increases in tissue pressure may collapse capillary beds and lead to tissue ischemia.

Pepsinogen and protein concentrations were determined in blood samples, collected from the left gastroepiploic artery and vein, and in abomasal lymph from 15 steers naturally infected with Ostertagia ostertagi and 4 uninfected steers. In steers with type-1 ostertagiosis, the concentration gradient between the mucosal interstitium and the blood alone could account for higher than normal serum pepsinogen concentrations. High interstitial pepsinogen concentrations may have resulted from increased epithelial permeability or increased pepsinogen production and secretion. However, in steers with type-2 ostertagiosis, the concentration gradient could not entirely account for the high serum pepsinogen concentrations, suggesting that capillary permeability or surface area may have been altered. Lymphatic uptake contributed pepsinogen to the blood in all infected steers.

Microvascular permeability characteristics were evaluated in digits of 7 adult horses. After capillaries were isolated and an extracorpeal perfusion circuit for the digit was established, a lymphatic vessel draining the distal portion of the phalangeal region was cannulated at the level of the coronary band. Venous pressure was increased in a stepwise manner, and lymph flow, lymph protein concentration (Cl), and plasma protein concentration (Cp) were determined after measured variables were allowed to reach steady state. Lymph-to-plasma protein concentration ratios (Cl/Cp) and lymph and plasma oncotic pressures were determined from samples collected during steady state. The osmotic reflection coefficient was determined after Cl/Cp became constant, regardless of increasing lymph flow, and was expressed as 1 - Cl/Cp. The osmotic reflection coefficient for the digit was 0.67. Seemingly, the microvasculature bed of the digit was relatively permeable and could maintain only 67% of the endogenous macromolecules within the vasculature.

The purpose of this retrospective analysis was to determine if fluorine-18 fluorodeoxyglucose-positron emission tomography/computed tomography (18F-FDG PET/CT) could potentially be an accurate staging tool for detecting metastatic lymph nodes in dogs with appendicular osteosarcoma based on the quantitative measurement of the maximum standard uptake value (SUVmax) of lymph nodes. A total of 53 dogs were identified that presented for staging via 18F-FDG PET/CT for primary appendicular osteosarcoma. Patients were categorized according to lymph node status of having either metastatic or non-metastatic nodes based on cytological or histological analysis. Maximum standard uptake (SUVmax) values of the sampled lymph node(s) were recorded and 3/77 (3.9%) of sampled lymph nodes were confirmed metastatic. A Mann-Whitney test revealed a statistical difference in the SUVmax of the metastatic versus non-metastatic lymph nodes [median: 6.6 to 95% confidence interval (CI): 2.56 to 14.37 versus 2.18 95% CI: 2.32 to 3.17, respectively, P-value = 0.05]. This retrospective analysis revealed a significant difference in the SUVmax as measured on 18F-FDG PET/CT between metastatic lymph nodes and non-metastatic lymph nodes in canine patients afflicted with appendicular osteosarcoma, in spite of the small numbers analyzed. While these results are promising, they should be interpreted with caution and further studies are justified.