Milk antimicrobial drug residue assay results in cattle with experimental, endotoxin-induced mastitis.

Antimicrobial drug residue testing was performed on milk samples obtained from 8 cows with experimental endotoxin-induced mastitis, using 4 commercially available assay kits. Although none of the cows in the study received antimicrobials, only 1 of the 4 assay procedures, assay C, had consistently negative results (specificity = 1.00). The proportion of positive assay results varied from 0 to 1.00 among combinations of sampling time, sample status (endotoxin-infused quarter vs composite noninfused sample). The proportion of positive results found when assay C was used (0) differed significantly from the proportion found when the 3 other assays were used. The proportion of positive results did not differ significantly between assay A (0.45) and assay B (0.48); however, both assays had a significantly lower proportion of positive assays than did assay D (0.86). Logistic regression models were developed predicting positive milk antimicrobial drug residue assay results as a function of assay kit, sample status, and time interval following experimental challenge exposure. Using assay A as a baseline risk, assay B and assay D were more likely to have positive assay results, and assay C had a decreased risk of positive assay results. Milk samples from endotoxin-infused quarters were at increased risk for positive assay results, compared with noninfused composite samples. Samples collected from endotoxin-infused quarters or control quarters were at increased risk for positive assay results following the intramammary infusion of endotoxin. Our findings suggest that specificity of milk antimicrobial drug residue assays varies greatly among assay kits and that intramammary inflammation may increase the proportion of false-positive assay results.     

Effects of number of lambs suckled and supplemental protein source on lactating ewe performance

Effects of number of lambs suckled and supplemental protein source on ewe performance were determined. Lactation performance of ewes nursing twin or triplet lambs was compared in Exp. 1 and 2. In Exp. 1, ewes giving birth to and nursing triplets produced 21% (P less than .05) more milk/unit metabolic body weight, were 10% more efficient in the conversion of feed to milk and produced 26% (P less than .05) more kg of lamb/ewe on d 42 of lactation than did ewes giving birth to and nursing twins. In Exp. 2, lactation performance of ewes giving birth to triplets and rearing only two lambs was compared with performance of ewes giving birth to triplets and rearing three lambs. Ewes rearing three lambs produced 28% (P less than .08) more milk and were 26% (P less than .05) more efficient in converting feed to milk than were those rearing two lambs. This suggests that direct nursing stimulation of the mammary gland is responsible for the improvement in milk production observed when ewes nurse additional lambs. The efficacy of slowly degradable protein sources for improved lactation was studied in Exp. 3 and 4. When blood meal was fed to twin-rearing ewes at 3.30% of the diet (25% of total dietary protein), milk production was greater (3,176 vs. 2,506 g/d, P less than .05) and efficiency of milk production was greater (1.05 vs .79 g milk/g feed, P less than .05) than when ewes were fed supplemental soybean meal. Ewes in this experiment fed supplemental meat and bone meal also tended to produce more milk than those fed soybean meal.(ABSTRACT TRUNCATED AT 250 WORDS)     

Effects of ram preexposure and ram breed on fertility of ewes in summer breeding

Suffolk x Rambouillet ewes were used in two consecutive years to test the ability of Dorset and Suffolk yearling rams to stimulate ovulation and estrus in early summer (late June and July) breeding. After spring weaning about June 1, ewes were randomly divided into three groups and for 2 wk either were isolated from rams or were preexposed to either yearling Dorset or Suffolk rams by penning of rams in proximity to ewes. Ewes then were rerandomized into two groups for joining with either yearling Dorset or Suffolk rams fitted with marking harnesses. Serum progesterone profiles and crayon marks were used as indicators of ovulation and estrus. Overall lambing rate was not different among preexposure treatments for the 2 yr. However, early lambing rate (in the first 14 d of lambing season) was significantly affected by preexposure group (24% for Dorset vs 9% for Suffolk and 10% for isolation), especially in the 2nd yr (31% for Dorset vs 8% for both Suffolk and isolation). Ewes preexposed to Dorsets also lambed 10 d earlier (P less than .05) than ewes preexposed to Suffolks in yr 2, but the groups did not differ in yr 1. Ewes exposed to Dorset rams for breeding had higher overall lambing rates than ewes bred to Suffolks (75% vs 54%), especially in the 1st yr (77% vs 48%). Lambs sired by Dorset rams were born 6 d earlier in yr 1 (P less than .05) but only 1 d earlier in yr 2. Data from both years indicate that Dorsets are superior to Suffolks in ability to sire lambs in fall lambing systems.     

Effects of repeated Strongylus vulgaris inoculations and concurrent ivermectin treatments on mesenteric arterial lesions in pony foals

Eight of 10 pony foals reared under helminth-free conditions were inoculated PO with 50 Strongylus vulgaris infective larvae/week for 4 weeks, at which time 1 foal died of acute verminous arteritis. Inoculation of 7 remaining foals continued at 2-week intervals for 20 weeks. Of the 7 foals, 3 were treated with ivermectin (0.2 mg/kg of body weight) in an oral paste formulation at experiment weeks 8, 16, 24; 4 foals were not treated. Two foals were not inoculated or treated and served as controls. After the first ivermectin treatment, ivermectin-treated foals had fewer days (12 +/- 2.9) with rectal temperatures greater than 38.6 C than did nontreated foals (23.3 +/- 3.8). Mean baseline rectal temperatures were 38 +/- 0.2 C. Adverse clinical reactions to ivermectin treatment were not observed in foals. Foals were euthanatized and necropsied 3 weeks after the last ivermectin treatment (week 24). Ivermectin was effective in reducing S vulgaris arterial larval and intestinal adult parasite numbers by 100% in 3 treated foals. Strongylus vulgaris arterial larvae and/or adults were recovered from all 4 nontreated inoculated foals. One nontreated inoculated foal lacked arterial larvae or active arterial lesions, indicating that protective resistance had developed in this individual. Marked gross and histopathologic lesions typical of chronic S vulgaris infection were observed in the 3 nontreated inoculated foals with arterial larvae. Repeated killing of intra-arterial S vulgaris fourth-stage larvae in ivermectin-treated foals did not exacerbate lesions associated with verminous arteritis or induce unique lesions associated with repeated destruction of arterial larvae.(ABSTRACT TRUNCATED AT 250 WORDS)     

Complications associated with immunotherapy of equine phycomycosis

Five horses with pythiosis of the limbs were treated unsuccessfully by surgery or topical application of amphotericin B, or both. Follow-up immunotherapy resulted in 1 horse responding favorably. Three horses were cured of the fungal infection but developed osteitis or deep-seated laminitis, which necessitated their destruction. The remaining horse, which had severe anemia, died before the course of vaccination was completed.     

Influence of Post‐Mortem Sperm Recovery Method and Extender on Unstored and Refrigerated Rooster Sperm Variables

Many post‐mortem sperm collection techniques have been described for mammalian species, but their use in birds is scarce. This paper compares the efficacy of two post‐mortem sperm retrieval techniques ‐ the flushing and float‐out methods ‐ in the collection of rooster sperm, in conjunction with the use of two extenders, i.e., L&R‐84 medium and Lake 7.1 medium. To determine whether the protective effects of these extenders against refrigeration are different for post‐mortem and ejaculated sperm, pooled ejaculated samples (procured via the massage technique) were also diluted in the above extenders. Post‐mortem and ejaculated sperm variables were assessed immediately at room temperature (0 h), and after refrigeration at 5°C for 24 and 48 h. The flushing method retrieved more sperm than the float‐out method (596.5 ± 75.4 million sperm vs 341.0 ± 87.6 million sperm; p < 0.05); indeed, the number retrieved by the former method was similar to that obtained by massage‐induced ejaculation (630.3 ± 78.2 million sperm). For sperm collected by all methods, the L&R‐84 medium provided an advantage in terms of sperm motility variables at 0 h. In the refrigerated sperm samples, however, the Lake 7.1 medium was associated with higher percentages of viable sperm, and had a greater protective effect (p < 0.05) with respect to most motility variables. In conclusion, the flushing method is recommended for collecting sperm from dead birds. If this sperm needs to be refrigerated at 5°C until analysis, Lake 7.1 medium is recommended as an extender.     

Experience and confidence of final year veterinary students in performing desexing surgeries

AIMS: To describe the level of experience and confidence of veterinary students in performing canine and feline desexing procedures at the end of their final clinical year.

METHOD: A cross-sectional survey was conducted with veterinary students at Massey University in November 2017 after completion of their final clinical year. The questions included career plans after graduation, number of assisted and unassisted desexing procedures performed, approximate time to complete desexing surgeries, level of confidence with different aspects of desexing surgeries, what aspects of their desexing surgery training were most helpful, and what could be done to improve training in desexing surgical skills in veterinary school.

RESULTS: The survey was completed by 70/95 (74%) students in their final clinical year. Among respondents, 55/70 (70%) had performed >2 unassisted feline neuters before graduation. However 38/70 (54%) students had never performed an unassisted feline spay, 31/70 (44%) had never performed an unassisted canine neuter, and 44/70 (63%) students had never performed an unassisted canine spay. The median reported times to complete a feline neuter, feline spay, canine neuter, and canine spay were 9, 40, 30 and 60 minutes, respectively. The median level of confidence for these procedures were 9, 6, 7 and 5 (on a scale from 1=least confident to 10=most confident), respectively. The reported time to complete procedures and the confidence in performing procedures did not change markedly with increasing total number of procedures performed. Students were most concerned about their ability to perform the desexing procedures in a reasonable amount of time and to prevent post-operative bleeding from occurring. Students were least concerned with their ability to manage post-operative pain in patients and to select the appropriate suture material. Free-text comments revealed that 62/70 (89%) students wanted more hands-on surgical experience prior to graduation.

CONCLUSION AND CLINICAL RELEVENCE: Many students are currently completing veterinary school with limited experience and low confidence with performing routine canine and feline desexing procedures. Further research is needed to identify the most effective ways for addressing this issue within the constraints of the veterinary curriculum and teaching hospital resources.     

Vaginal isolation of beta‐haemolytic Streptococcus from bitches with and without neonatal deaths in the litters

The aim of the study was to identify beta‐haemolytic streptococci in the vagina of bitches who had delivered healthy litters and bitches who had delivered litters in which neonatal deaths occurred. Fifty‐one bitches divided into two groups were used. Group 1 (G1) included 28 bitches that had delivered healthy litters and group 2 (G2) included 23 bitches that had delivered puppies who died in the neonatal period. Two vaginal samples were taken, one in proestrus and the other at the end of gestation (EG). Beta‐haemolytic Streptococcus (BS) was isolated from 16 bitches (57%) in G1 and from 21 bitches (91%) in G2. The bacteriological cultures, serological tests (Streptex^®) and PCR assay allowed identification of Streptococcus canis and Streptococcus dysgalactiae in G1 and G2. Ultramicroscopic studies allowed the observation of M Protein and capsules in strains of S. dysgalactiae and S. canis in G1 and G2. The S. canis strains isolated from G2 showed thicker capsules than S. canis strains isolated from G1 (234 ± 24.2 vs 151.23 ± 28.93 nm; p < .001.). No differences were observed in capsule thickness between strains of S. dysgalactiae isolated from G1 and G2 (210 ± 13.54 vs 211.66 ± 19.67 nm; p > .70). All strains of beta‐haemolytic Streptococcus isolated were penicillin sensitive. Penicillin was administered from EG to 5 days post‐partum in 10 G2 females with isolation of BS (G2A). Saline solution was administered in eleven G2 females with isolation of BS (G2B). Ninety per cent of the puppies survived in G2A and 25% survived in G2B. Our results suggest BS is involved in canine neonatal deaths.     

Morphology of alpaca (Vicugna pacos) embryos in the first third of pregnancy

The breeding of South American camelids is the main economic activity of the high Andean region of South America and it, is potentially, the most profitable resource in of the Puna environmental conditions of the Puna. The duration of the gestation in alpaca is 339.7 ± 12 days. The objective of the present work was to macroscopically and microscopically describe the ontogenic development of the splanchnic cavities of the alpaca and to determine the gestational time in which the post‐cranial ossification centers are observed in the embryos/fetuses of this species, from day 21 to 107 of gestation. The documentation of normal ontogenic development, which is vacant for this period, is of the utmost importance to understand the consequences of the alterations at the different gestational times, as well as for the estimation of the gestational age in the case of abortions. Forty‐seven alpaca specimens of both sexes, at different times of their gestational development, collected during slaughter at local slaughterhouses of the Department of Huancavelica, Peru, were evaluated. Specimens were assigned to seven groups according to their morphological characteristics. The embryogenesis in the alpaca was characterized by a series of changes comparable to those occurring in other mammals with similar gestational periods. Despite these similarities, species differences were found in some organs as stomach, which are observed too in adult individuals.