Theriogenology Clinical Poser Babiche Heil 27

THERIOGENOLOGY CLINICAL POSER

Babiche Heil | babiche@matavet.co.nz

From page 27

While examining the fetal membranes of a mare after a normal foaling you notice the structures pointed out by the white arrows on the chorioallantois in figures A and B. The structures are ~2 cm long.

(i), What are these structures?

These structures are chorioallantoic pouches.

(ii), What is their significance?

Chorioallantoic pouches are small, pedunculated outgrowths arranged in a circle on or near the umbilical cord attachment. They hang as folds and represent invaginations into the allantoic cavity. Inspissated endometrial cup material and epithelial debris may accumulate in the pouches giving them a more round or cystic appearance (B). These pouches are normal findings when examining an equine placenta post-foaling.

Bozorgmanesh, R et al. Symmetric dimethylarginine concentrations in healthy neonatal foals and mares. J Vet Int Med 2021; 35(6): 2891-2896

Serum and EDTA whole blood samples were collected by ‘convenience sampling’ from 104 mares in their last month of pregnancy and then from mares and 125 foals at <12 hours and 2, 7 and 30 days postbirth. Upper limits for SDMA concentrations in foals were above the adult horse reference interval and decreased from 70 mu g/dL (range, 7-100 mu g/dL) to 18 mu g/dL (range, 6-27 mu g/dL) during the first few weeks of life.

NOTE: There does appear to be quite a wide biologic, breed and laboratory variability in results for SDMA testing (e.g. https://pubmed.ncbi.nlm.nih.gov/33524207/) so it would be unwise to rely solely on this measurement as evidence of renal GFR dysfunction in equids just yet. See conclusion in Gough and McGovern (2021) below.

Gough, RL and McGovern, KF. Serum symmetric dimethylarginine (SDMA) concentration in healthy neonatal Thoroughbred foals. Eq Vet J 2021; 35(6): 2891-2896. https://doi.org/10.1111/jvim.16295

Reference ranges are established in healthy adult horses (≤ 14 µg/dL) and concentrations are increased in horses with acute kidney injury (median 32 µg/dL; range 15-92). Blood samples were collected from 120 TB foals 1-34 hours old. Median value (95% CI) for SDMA concentration was 69.0 µg/dL (63.0, 75.0; range 35.0-376.0). A cut-off value of 168 µg/dL would include 95% of individuals and is therefore suggested. Serum SDMA concentration was correlated with age (R = -0.3, P = 0.003), creatinine concentration (R = 0.6, P ≤ 0.001) and urea concentration (R = 0.3, P = 0.002). Neonatal foal SDMA concentration is higher than in adult horses, than in older foals and then in adults with acute kidney injury. Therefore, currently SDMA cannot be used as a marker of renal dysfunction in this age group. Further work is required to assess whether SDMA concentration is increased in neonates with renal disease and, if so, what cut-off should be used.

Pusterla, N et al. Investigation of Three Newly Identified Equine Parvoviruses in Blood and Nasal Fluid Samples of Clinically Healthy Horses and Horses with Acute Onset of Respiratory Disease. ANIMALS 2021; 11(10: 3006. https:// www.mdpi.com/2076-2615/11/10/3006

Three novel equine parvoviruses (equine parvovirus hepatitis (EqPV-H), equine parvovirus CSF (EqPV-CSF) and equine copivirus (Eqcopivirus)) have recently been discovered in horses with respiratory signs. Nasal fluid samples and blood from 667 equids with acute onset of fever and respiratory signs were analyzed for the presence of common equine respiratory pathogens as well as for the novel parvoviruses; 87 clinically healthy horses served as controls. Samples from 117/667 sick horses tested qPCR-positive for at least one of the three parvoviruses. Co-infections with common respiratory pathogens and parvoviruses were seen in 39/667 sick equids. All 87 clinically healthy horses tested qPCR-negative for all tested common respiratory pathogens, and 10/87 healthy horses tested qPCRpositive for one of the equine parvoviruses. It was suggested that the three novel equine parvoviruses did not contribute to the clinical picture of equids with respiratory disease in the sample population.

Bookbinder, L and Schott, HC. Refeeding syndrome in a miniature donkey. J Vet Emerg Crit Care 2021; 31(5): 668673. https://pubmed.ncbi.nlm.nih.gov/34259376/

Refeeding syndrome developed in an aged miniature donkey gelding during treatment of suspected enterocolitis. Hypophosphatemia was seen as ileus and neuromuscular weakness despite a 3-day history of hyporexia, increased body condition (7/9), and adherence to nutritional recommendations for critically ill equids including nasogastric enteral feeding with a commercial equine diet. Hypophosphatemia of <0.16 to 0.3 mmol/L [reference 0.5–1.4 mmol/L] developed despite this enteral supplementation and was ultimately corrected by intravenous administration of sodium phosphate solution. It was suggested that risk factors for refeeding syndrome in equids may be broader than previously recognized and include critically ill equids at risk for insulin dysregulation that may have unique nutritional co-morbidities and requirements. Revised best-practice nutritional guidelines and improved supplementation products are required to improve equine critical care.

Magalhaes, HB and Canuto, LEF. Electrolytes and pH of Mammary Gland Secretions Assessments to Detect Impending Parturition and Associations with Placental and Neonate Features in Donkeys. J Eq Vet Sci 2021; 102: 103636. https://doi.org/10.1016/j.jevs.2021.103636

Each multiparous jenny (n = 37) had mammary secretion assays and gestational and parturition variables documented. Mammary secretion pH profiles assessed visually and classified as fast pH drop (1), slow pH drop (2), and alkaline pH (3) as previously described for horses. The overall gestation length was 374 ± 8.7 days [range 357 to 390 days]. There were no differences for gestation lengths for jennies delivering colts (374 ± 2.1, range 357-385 days), versus those delivering fillies (373 ± 2.3 range 358-390 days). The ratio of foal birthweight to dam bodyweight was 10%, and the ratio to fetal membrane weight was 11%. There was a significant reduction in Na+ and an increase in Ca2+, Mg2+, and K+ concentrations leading to foaling. The pH showed a 90% sensitivity for foaling within 24 hours, whereas the specificity was 70%, and the PPV and NPV values were 40% and 97%. Of interest, Ca2+ (>10 mmol/l) displayed a sensitivity and specificity of 71% and 85%, whereas the PPV and NPV were 72% and 84%. Also, 65% of the jennies displayed slow pH drop and foaled with a mean acidic pH of 6.4 ± 0.02. Conversely, 32% of the jennies showed a fast pH drop from day minus-1 (7.3 ± 0.2) to the day of foaling with an average pH of 6.6 ± 0.08. One jenny foaled with high pH = 7.5. There were weak and negative correlations between pH and Ca2+, Mg2+ and K+ (P<.05). In addition, Ca2+ displayed a weak but significant correlation with Mg2+, Na+ and K+. Thus, daily pH measurements of the mammary gland secretions can predict foaling in jennies, whereas Ca2+ was not as useful. Contrary to horses that most mares present a fast pH drop profile, most jennies showed a slow pH drop profile. The sex of foal did not affect the gestational length and fetal/maternal and fetal membrane proportions in donkeys.

Geurden T et al. Three-year study to evaluate an anthelmintic treatment regimen with reduced treatment frequency in horses on two study sites in Belgium. Vet Parasitol 2021; 298: 09538. https://doi.org/10.1016/j.vetpar.2021.109538

A reduced treatment frequency anthelmintic regimen was evaluated on 2 studs in Belgium over 3 seasons. Previously ivermectin (IVM) was used <4 times a year with moxidectin (MOX) used >6 times a year with reduced egg reappearance periods detected in some of the treated horses. In the present study, all horses were treated with IVM or MOX in the spring and in autumn. Faecal egg counts (FEC) were conducted every two weeks and when >250 epg that horse was treated with pyrantel embonate. No increase in parasitic disease over the three-year period was observed. A cyathostomin life-cycle model was used to evaluate long term effects of various treatment regimens and this indicated that the whole-herd treatment regimen with at least 4 macrocyclic lactone treatments annually led to 2–3 times faster development of resistance than any of the alternative treatment regimens [1 or 2 IVM or MOX, plus PYR for hi-shedders]. Further lowering the treatment frequency or applying even more selective treatments enhanced the delay in resistance development, but to a lesser extent.