2015 ACVIM Forum Research Abstract Program

Three weeks following the PEG tube placement their position was confirmed endoscopically. In both horses the tube was located within the ventral glandular fundus approximately 10 cm below the margo plicatus adjacent to the lesser curvature. At this point a pH probe (Comfortec PLUS, Sandhill Scientific, CO, USA) was fitted retrograde through the PEG tube with its location confirmed endoscopically. The probe's insertion distance was noted for future placement. The horses were then adapted to one of two diets; a hay only diet (HAY) or a high grain/low fiber (HG/LF) diet. The HG/LF diet consisted of 1% BW each of grain and hay per day, divided equally into two meals. Each horse was then monitored on their diet for a period of 5 consecutive days. To achieve this; the pH probe was attached to a continuous data logger (Zephyr pH, Sandhill Scientific, CO, USA). The probe was calibrated prior to placement each day and then inserted the previously determined distance and secured. Data recording commenced at 8 am and continued for 23 hours each day. The probes contained two measurement points, 5 cm apart. The location of probe 1 was approximately 1 cm from the glandular mucosa while the second probe sat 5 cm deeper, presumably within the ingesta. Data (median (IQR)) for each horse is shown below. This report describes the successful instrumentation of horses with permanent PEG tubes and their use for the measurement of intra-gastric pH using a technique that allows measurement at multiple points within the stomach. Further, the technique allows for the monitoring of intragastric pH without disturbance to the horse's normal eating behavior, a major limitation of many other models. The procedure can be performed in the standing, sedated horse with minimal specialized equipment. This report describes severe myelosuppression in four American Quarter Horses associated with ingestion of mycotoxin-contaminated hay. The index case (11 year old mare) presented with lethargy, acute perineal edema, hematochezia, fever, patchy alopecia, and petechiation. The horses had recently been fed a new batch of hay (which was later revealed to be improperly cured), which initially caused feed aversion. Bloodwork from the mare showed severe neutropenia and thrombocytopenia and prolonged prothrombin time. Profound myeloid and megakaryocytic hypoplasia was found on evaluation of bone marrow. The mare developed septic peritonitis and was treated aggressively for 8 days with anti-inflammatories, antibiotics, and blood transfusions prior to acute decompensation necessitating euthanasia. Of the remaining horses, two developed similar hematologic findings and all three had alopecia. A second case (19 year old gelding) was referred for treatment with milder signs of petechiation and patchy alopecia and was noted to have similar bone marrow findings to the mare; this horse recovered after treatment with antiinflammatories and antibiotics. The two remaining horses (8-and 6-year old mares) were managed conservatively and recovered. Toxicological testing on the hay revealed high levels of mycotoxins, including T-2 toxin and vomitoxin (both known myelotoxicants; 1627 ppb and 1.1 ppm, respectively).