Effects of cereal grain supplementation on apparent digestibility of nutrients and concentrations of fermentation end-products in the feces and serum of horses consuming alfalfa cubes.

Twenty geldings (five groups; similar age and BW) were used in a completely randomized design experiment to determine effects of grain supplementation of an alfalfa-cube diet on apparent nutrient digestibility and hindgut fermentation. The geldings were housed individually, fed their diets in two equal meals (0600 and 1800), and adapted to five dietary treatments over 6 wk. The treatments were alfalfa cubes (1% of BW; DM basis) without (control) or with one of four rolled cereal grains (i.e., barley, corn, naked oats, or oats) to provide a target level of 0.4% of BW as total nonstructural carbohydrates (TNC). Due to acute laminitis, three geldings (one in the control group and two in the barley group) were excluded. Because of this and multiple incidents of gas colic, TNC level was decreased to 0.2% of BW to ensure the geldings' health throughout the adaptation (7 d) and sample collection (5 d) periods. Grain intakes varied (P < 0.05) and reflected the different TNC concentrations. Apparent digestibilities of DM, OM, CP, NDF, ADF, and cellulose were not affected (P > 0.05) by grain supplementation and averaged 63.2, 63.1, 79.5, 42.7, 39.9, and 50.3%, respectively. Regardless of the source, grain supplementation increased (P < 0.05) apparent digestibility of TNC (from 85.6 to 94.6%) and decreased (P < 0.05) fecal pH (from 7.04 to 6.74). Fecal concentrations of total VFA (mg/g of DM) were greatest for the barley and naked oats diets (averaging 11.73), intermediate for the oats diet (8.00), and least for the control and corn diets (averaging 5.00; P < 0.05). Fecal concentrations of lactate (microg/g of DM) were greatest for the barley diet (254), intermediate for the oats diet (138), and least for the remaining diets (averaging 100; P < 0.05). Fecal concentrations of NH3 N (mg/g of DM) were greatest for the naked oats diet (1.68), intermediate for the barley and oats diets (averaging 0.86), and least for the remaining diets (averaging 0.63; P < 0.05). Serum concentration of lactate was 46% higher (P < 0.05) for the control than for the grain diets (averaging 0.05 mg/100 mL). Feeding barley, corn, naked oats, and oats contributed to 13, 15, 8, and 20% higher (P < 0.05) serum NH3 N concentrations than the control diet (0.25 mg/100 mL). Higher (P < 0.05) serum concentrations of urea N (mg/100 mL) were detected for the control, barley, and naked oats diets (averaging 25.28) than for the corn or oats diets (averaging 22.21). Results suggest that horses consuming alfalfa cubes could be supplemented with rolled barley, corn, naked oats, or oats at levels not exceeding 0.2% of BW as TNC without affecting nutrient digestion or overall health negatively.

Effects of anesthesia of the palmar digital nerves on kinematic gait analysis in horses with and without navicular disease.

OBJECTIVE: To determine the effect of local anesthesia of the palmar digital nerves on forelimb kinematics in Quarter Horses with and without navicular disease. ANIMALS: 12 adult Quarter Horses; 5 clinically normal (sound) and 7 with navicular disease. PROCEDURE: Kinematic measurements were made on adult horses trotting on a treadmill, before and after palmar digital nerve block (PDNB). Twenty-three displacement, joint angle, and temporal gait measurements of the right forelimb and head were made for 5 strides in each horse. Initial (before local anesthesia) right forelimb measurements were obtained after a left forelimb PDNB. Kinematic measurements were compared before and after PDNB of the right forelimb by multiple ANOVA with an alpha = 0.05, adjusted for posthoc comparisons by Bonferroni correction. RESULTS: In sound horses, the only significant change in kinematic measurements after PDNB nerve block was in the maximum extension of the metacarpophalangeal joint at mid-stance, which was decreased by an angle of 2 degrees. In horses with navicular disease, mean maximum extension of the metacarpophalangeal joint during stance phase and maximum flexion of the carpal joint during swing phase were significantly increased after PDNB. Also, total stance phase, cranial stance phase, and break-over durations were significantly shorter. In horses with navicular disease, differences between minimum head heights during stance phase of each forelimb and total vertical head excursion during a complete stride were significantly smaller after PDNB. CONCLUSION: Several kinematic measurements of gait can be used to determine improvement of lameness in horses with navicular disease after PDNB block while trotting on a treadmill.

Acute arsenic toxicosis in five horses.

Five adult horses presented with acute clinical signs of watery diarrhea, excessive salivation, muscle tremors, ataxia, and depression. Four died within 24 hours and the fifth was euthanatized approximately 48 hours after onset of clinical signs. Necropsy finds in two of the horses included hyperemia of gastric mucosa, intestines filled with green to black watery fluid, and multifocal to coalescing, hemorrhagic 1.0-2.0-cm-diameter ulcers of the mucosa of the cecum and large colon. Histopathologic changes in the cecum and large colon consisted of mucosal necrosis and ulceration, vascular thrombosis, necrosis of submucosal blood vessels, and infiltration by mixed mononuclear inflammatory cells and neutrophils. Arsenic toxicosis was suspected. The owner had not been feeding the horses any grain; however, a mixture of grain and pink powder was found in the pasture. Liver arsenic concentrations in the two horses were 14.0 and 11.0 ppm, a sample of renal cortex contained 108 ppm arsenic, and the grain/powder mixture found in the pasture was positive for arsenic at > 3,000 ppm. kidney lead concentrations were 6.5 and 4.2 ppm. Results were consistent with lead arsenate or lead arsenite poisoning.

Case control and historical cohort study of diarrhea associated with administration of trimethoprim-potentiated sulphonamides to horses and ponies.

Trimethoprim-potentiated sulphonamides (TPS) are among the most frequently administered antimicrobials in equine medicine. Anecdotally, TPS has been implicated as a cause of mild to moderate diarrhea in horses. The purpose of this study was to document the prevalence of diarrhea in horses receiving TPS, to characterize the severity of the diarrhea, and to identify any other factors associated with the development of diarrhea. A 2-part study was designed to identify the prevalence of diarrhea associated with TPS in our clinic population. Part I was a case-control retrospective study of 135 records over a 10.5-year period from January 1, 1980 through June 30, 1990. Part II was a historical cohort study of 784 records over a 37-month period from July 1, 1990 through July 31, 1993. There was no significant difference in the occurrence of diarrhea associated with TPS therapy in either study. The occurrence of diarrhea was 21% and 3% in parts I and II, respectively. Significant factors identified in association with diarrhea in part I were duration of hospital stay, and antibiotic therapy other than TPS or penicillin. Significant factors identified in part II included other antibiotic therapy, penicillin therapy, and combined penicillin and TPS therapy. Diarrhea does occur after the administration of antibiotics, most likely because of the alteration of the patient's normal intestinal flora. Diarrhea was noted in association with administration of TPS in this study; however, its prevalence was not significantly different than that in horses receiving other antibiotics, such as penicillin and its derivatives.

Jejunal intussusception: a complication of functional end-to-end stapled anastomoses in two ponies.

Jejunojejunal intussusception occurred after jejunal resection and stapled functional end-to-end anastomosis in two pony mares. In both mares, the lead point of the intussusception was the stapled functional end-to-end (FEE) anastomosis. The stapled free ends of jejunum were oversewn with an inverting suture pattern. A possible explanation for development of the intussusception was the acute angle created in the intestine by the FEE anastomosis. This angulation may have impaired flow of ingesta causing motility changes that predisposed the site to intussusception. Because the oversewn blind intestinal ends acted as the lead point for formation of the intussusception, it may be inadvisable to oversew the stapled anastomotic ends.

Bilateral tibial metaphyseal stress fractures associated with physitis in a foal.

A 7-month-old Appaloosa foal had bilateral hind limb lameness and was unable to rise from recumbency without assistance. Lameness could be exacerbated by tarsal flexion and a firm swelling at the distomedial aspect of the tibias was associated with a marked pain response when palpated. Radiography revealed enlargement of the distal tibial metaphysis physis (compared with normal), and radiolucent fissure lines extending proximally from the physis into the metaphysis at its medial aspect. Treatment included rest and dietary adjustment. Although clinical signs initially resolved following treatment, the problem recurred when the foal was 14 months old. Further treatment included 7 months of pasture rest without forced exercise, after which the foal was reported to be clinically normal.