Comparison of the persistent efficacy of the injectable and pour-on formulations of doramectin against artificially-induced infection with Dictyocaulus viviparus in cattle

The persistent efficacy of the injectable and topical formulations of doramectin was compared against experimental challenges with infective larvae of Dictyocaulus viviparus in two separate studies. Four groups of 10 randomly-assigned calves, negative for lungworm larvae by the Baermann technique, were used in each study. Calves were treated subcutaneously in the midline of the neck or poured down the midline of the back with saline (1 ml/50 kg. injection: 1 ml/10 kg. pour-on) on Day 0 or doramectin (200 microg/kg = 1 ml/50 kg. injection: 500 microg/kg = 1 ml/10 kg. pour-on) on Day 0, 7, or 14. Two additional calves from the same pool of animals were randomly assigned as larval-viability monitors and received no treatment. Calves were inoculated daily with a gavage of approximately 100 larvae of D. viviparus from days 35 to 49 for the injectable study and days 28 to 42 for the pour-on study. The two larval viability monitor calves received approximately 3000 infective larvae in the same manner on Day 49 or 42 for the injectable and pour-on studies, respectively. Equal numbers of calves from each treatment group as well as the larval viability monitor calves were necropsied on days 14 and 15 after the last lungworm inoculation to enumerate the worm burden. The worms recovered were quantified and identified. For each study, geometric mean worm recoveries for each treatment group were back transformed from the natural log-transformed data (worm count +1) and were used to estimate percentage reduction. Doramectin injectable solution was 100.0% efficacious against lungworms for up to 49 days and the pour-on formulation was 100.0%, 93.1% and 81.5% effective in reducing lungworm infection resulting from challenge infection for up to 28, 35, and 42 days post-treatment, respectively.     

Piglet Birthweights and the Order of Farrowing

The relationship between birthweight and order of farrowing was determined from the records of 202 attended farrowings. Statistical analysis of all individual birthweights showed the first-born piglet to be heavier (P<0.05) than the last-born. The order of farrowing might not be entirely random, as further evidenced by a delayed expulsion of stillborn piglets; 70 per cent of these births occurred during the last third of the farrowing period.     

Characterisation of lymphocyte subpopulations in the skin and circulation of horses with sweet itch (Culicoides hypersensitivity)

Circulating lymphocyte numbers are elevated in horses with the allergic skin disease sweet itch and skin lesions are typified by an infiltrate of eosinophils and mononuclear cells, the latter of which have not been fully characterised. The aim of the present study was to characterise the lymphocyte subpopulations in the circulation and skin of ponies with sweet itch by flow cytometry and a newly developed modified alkaline phosphatase immunohistochemical technique. Sweet itch ponies were found to have significantly greater numbers of circulating CD5+ and CD4+ T-lymphocytes than normal animals. Increased numbers of CD3+ T-lymphocytes, most of which were CD4+, and eosinophils were present in the skin of these animals following intradermal injection of a Culicoides antigen extract (97 +/- 21 vs. 449 +/- 49 CD3+ T-lymphocytes/mm2 in deep dermis of vehicle vs. antigen injected sites; 83 +/- 8% CD4+ T-lymphocytes at antigen injected site). T-lymphocytes, which are thought to be important in the pathogenesis of human allergic skin disease, may therefore contribute to the development of sweet itch lesions via the release of cytokines which can cause eosinophil accumulation and activation. An understanding of the pathology of this disease may lead to a more rational approach to therapy.     

Potassium and nitrogen effects on carbohydrate and protein metabolism in alfalfa roots

An investigation was conducted to determine the effect of potassium (K) nutrition on alfalfa (Medicago sativa L.) growth and metabolism of root total nonstructural carbohydrates (TNC) and proteins, and to study whether nitrogen (N) fertilization overcomes N deficiency and low root protein concentrations caused by K deficiency. In Experiment 1, nodulated alfalfa plants were grown in plastic pots containing washed quartz sand and provided minus‐N Hoagland's solution containing 0, 0.6, or 6.0 mM K. Shoot and root K concentrations increased with increasing solution K. Root N concentrations were higher in plants receiving 6.0 mM K than in plants receiving 0.6 or 0 mM K, but shoot N concentrations were similar for all treatments. Plant persistence, shoots per plant, and shoot mass increased as solution K levels increased. Root starch concentration and utilization were positively associated with K nutrition. Total amylase activity was higher, but endoamylase activity was lower in roots of plants receiving 6.0 mM K compared to plants receiving 0.6 or 0 mM K. Root soluble protein concentrations were significantly higher in plants receiving 6.0 mM K than in plants receiving 0 or 0.6 mM K. In Experiment 2, plants were supplied with Hoagland's solution containing 10 mM N as ammonium (NH₄ ⁺) or nitrate (NO₃) with 0,3, or 6.0 mM K. The addition of N increased root N concentrations only in plants receiving 0 mM K. Plant persistence was reduced by NH₄ ⁺ application, especially in plants receiving 0 or 3 mM K. Root starch concentrations were markedly reduced in plants receiving NH₄ ⁺ at all K levels. The addition of NO₃ ^‐ had little effect on alfalfa root carbohydrate and protein metabolism and subsequent shoot growth. Potassium deficiency reduced starch and protein concentrations in roots; factors that were associated with poor persistence and slow shoot regrowth of alfalfa.     

Immunolocalization of angiogenic growth factors in the ovine uterus during the oestrus cycle and in response to Steroids

The vascular changes associated with endometrial maturation in preparation for embryo implantation depend on numerous growth factors, known to regulate key angiogenic events. Primarily, the vascular endothelial growth factor (VEGF) family promotes vascular growth, whilst the angiopoietins maintain blood vessel integrity. The aim was to analyse protein levels of VEGFA ligand and receptors, Angiopoietin‐1 and 2 (ANG1/2) and endothelial cell receptor tyrosine kinase (TIE‐2) in the ovine endometrium in the follicular and luteal phases of the oestrus cycle and in response to ovarian steroids. VEGFA and its receptors were localized in both vascular cells and non‐vascular epithelium (glandular and luminal epithelium) and stroma cells. VEGFA and VEGFR2 proteins were elevated in vascular cells in follicular phase endometrium, compared to luteal phase, most significantly in response to oestradiol. VEGFR1 was expressed by epithelial cells and endothelial cells and was stimulated in response to oestradiol. In contrast, Ang‐1 and Ang‐2 proteins were elevated in luteal phase endometrium compared to follicular phase, and in response to progesterone, evident in vascular smooth muscle cells and glands which surround TIE‐2‐expressing blood vessels. Our findings indicate that VEGFA is stimulated by oestradiol, most predominantly in follicular phase endometrium, and Ang‐1 and 2 are stimulated by progesterone and were increased during the luteal phase of the oestrus cycle, during the time of vascular maturation.     

Detection and isolation of Toxoplasma gondii from fresh semen of naturally infected dogs in Southern Brazil

The aim of this study was to isolate Toxoplasma gondii and determine the viability of the parasite in fresh semen samples of clinically healthy adult dogs naturally infected. Eleven seropositive dogs with T. gondii IgG antibodies from southern Brazil were selected to confirm the presence and viability of T. gondii in fresh semen samples using in vitro isolation in Vero cell culture, polymerase chain reaction (PCR) and sequencing analysis. The presence of viable T. gondii was confirmed by in vitro isolation and PCR in five semen samples. The ITS1 region of the isolated protozoa (TG S4) was amplified and sequenced. The nucleotide sequence obtained was 99% compatible with the T. gondii DNA sequences stored in the GenBank. It has been shown that T. gondii tachyzoites may be isolated in vitro from fresh semen samples of clinically healthy dogs seropositive for T. gondii.     

Retrospective evaluation of canine heart base tumours treated with toceranib phosphate (Palladia): 2011‐2018

Heart base tumours (HBT) occur commonly in older, brachycephalic dogs. A presumptive diagnosis is made based on location and appearance of the tumour via echocardiogram. Effective treatment options are limited to surgery (when feasible) or radiation therapy. Benefit of medical management is presently unknown. The goal of this retrospective study was to assess the efficacy and tolerability of toceranib phosphate for dogs with HBT. Twenty‐eight dogs with histologically, cytologically confirmed or presumed HBT were evaluated retrospectively. Twenty‐seven dogs were treated with single agent toceranib. One dog received combination therapy with concurrent metronomic chemotherapy. This dog was not included in response or survival analysis. Factors assessed included clinical signs, hematologic/biochemical parameters and response to treatment. For the 27 dogs receiving single agent toceranib, an overall response rate of 10% was found. Overall median survival time was 823 days (range, 68‐1190 days). The overall response rate for the dogs presenting with metastasis was 28.5%, with a median survival time of 532 days (range, 77‐679 days). This was not significantly different than the median survival time of 796 days for dogs who did not present with metastasis. Of the dogs displaying clinical signs at the time of diagnosis, 90% had improvement and 81% had complete resolution of signs after starting toceranib. Toxicity was seen in 54% of dogs with gastrointestinal distress as the most common toxicity but dose reductions were infrequent required. Results demonstrate that toceranib phosphate is a well‐tolerated and effective treatment for inoperable canine heart base tumours including dogs with advanced or metastatic disease.     

Reproductive Development of Santa Inês Rams During the First Year of Life: Body and Testis Growth,Testosterone Concentrations,Sperm Parameters,Age at Puberty and Seminal Plasma Proteins

We have investigated the reproductive development of the tropically adapted Santa Inês ram, the most common hair sheep in Brazil. From 8 to 48 weeks of age, 16 animals were evaluated for body and testis growth, semen parameters, testosterone concentrations and seminal plasma proteins, using two‐dimensional SDS‐PAGE. Animals were weaned at 30 days and kept in feedlots thereafter, receiving hay, concentrate (18% of crude protein) and mineral supplement. Body weight increased from 12.3 ± 0.7 to 54.3 ± 1.6 kg between 8 and 48 weeks (p < 0.05), but changes in thoracic perimeter and scrotal circumference were non‐significant after 36 weeks (p > 0.05). The percentage of motile sperm increased slowly until 23 weeks and more rapidly after that age, but significant changes in progressive motility occurred after 25 weeks. Presence of abnormal sperm related inversely to age. Most significant changes in sperm concentration occurred between 38 and 44 weeks (0.38 ± 0.05 to 1.14 ± 0.24 × 10⁹ cells/ml, p < 0.05) and testosterone reached its highest concentrations at 42 weeks, decreasing afterwards. Rams reached puberty at 28.2 ± 0.8 weeks. The number of protein spots on seminal plasma gels was similar from 15 to 18 weeks (45 and 47 spots; p > 0.05), increased until 24 weeks (141 spots) and 28 weeks (170 spots; p < 0.05) and remained without significant (p > 0.05) changes from 28 to 48 weeks (186 ± 10 spots). Furthermore, the intensity of selected spots on 2D maps increased (p < 0.05) between 15 and 28 weeks, which preceded or coincided with the main developmental changes in sperm motility and percentage of defective sperm in the ejaculates. These results will support future studies designed to characterize specific seminal plasma proteins whose expression relate to the development of testis, epididymis and accessory sex glands.