Laminar microvascular flow, measured by means of laser Doppler flowmetry, during the prodromal stages of black walnut-induced laminitis in horses.

OBJECTIVE: To measure changes in laminar microvascular blood flow (LMBF) over time in healthy horses and horses in the prodromal stage of black walnut-induced laminitis and to determine the effects of glyceryl trinitrate application on LMBF in horses with acute laminitis. ANIMALS: 10 healthy adult horses. PROCEDURE: Laser Doppler flowmetry was used to measure LMBF Baseline measurements were obtained, horses were given deionized water via a nasogastric tube, and measurements were obtained hourly for 12 hours. Twenty-four hours later, baseline measurements were again obtained, and horses were given black walnut extract. Measurements were obtained hourly for 12 hours or until development of Obel grade-3 laminitis. At this time, 5 horses were treated with phenylbutazone, and the other 5 were treated with phenylbutazone and glyceryl trinitrate, and measurements were obtained hourly for an additional 12 hours. RESULTS: LMBF was significantly decreased 1 and 2 hours after administration of the black walnut extract but then returned to near-baseline values for the next 6 hours. Eight hours after extract administration, there was a second significant decrease in LMBF that persisted until the end of the study. Glyceryl trinitrate had no effect on LMBF. Clinical signs of laminitis developed 8 to 12 hours after extract administration. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggest that in horses with black walnut-induced laminitis, there is an early decrease in LMBF followed by reperfusion prior to onset of clinical signs. Treatment with glyceryl trinitrate after development of clinical signs of laminitis did not have a significant effect on LMBF.

Evaluation of laser Doppler flowmetry for measuring coronary band and laminar microcirculatory blood flow in clinically normal horses.

Once daily for 3 days, laser Doppler flowmetry was used in 5 healthy, nonsedated adult horses to evaluate coronary band and laminar microcirculatory blood flow (MBF) in both forelimbs. The coronary band had significantly (P < 0.05) higher MBF than did the laminae on the days evaluated. Significant variation in MBF was not found over the 3-day measurement period in any one site. Significant (P < 0.05) variation was found in coronary band MBF among horses. This variation was not observed in laminar MBF. On occlusion of the digital arteries at the level of the fetlock, marked decrease in coronary band and laminar MBF was observed. Twenty minutes after IV administration of acetylpromazine, marked increase in coronary band and laminar MBF was observed. The technique was easily performed in standing nonsedated horses, did not inflict discomfort, lacked complications, and measurements were repeatable. This technique provides an index of digital MBF, either intermittently or continuously, avoiding introduction of invasive variables associated with other techniques.

Chemical involution of the equine parotid salivary gland.

The efficacy of eliminating parotid salivary secretions by retrograde infusion of 10% formalin, 2% chlorhexidine, or 2% or 3% silver nitrate solutions was evaluated in 10 horses. Solutions were kept within the parotid salivary gland for 90 seconds after infusion through parotid duct cannulae and then allowed to drain freely. Severed parotid ducts and surgical incisions were left to heal by second intention. All agents eliminated glandular secretions. There was less necrosis and suppurative inflammation after formalin infusion than after chlorhexidine and silver nitrate. Silver nitrate (2% and 3%) caused the most necrosis and inflammation.

Preliminary study of laryngeal sacculectomy in horses, using a neodymium:yttrium aluminum garnet laser technique.

In an attempt to ablate the laryngeal saccule as an alternative method of sacculectomy (conventially done through a laryngotomy incision for laryngeal hemiplegia) a neodymium:yttrium aluminum garnet laser was used transendoscopically in noncontact fashion in 6 horses. The procedure was easy, quick, and labor-saving, with few complications. Endoscopically, the lased sacculectomy site appeared healed at postsurgical day 42. On postsurgical day 42, microscopic examination revealed mucosal remnants under the granulation bed. Laser energy caused thermal damage to tissues adjacent to the lased saccule. Additional work must be done to refine the technique before it can be recommended for clinical applications.

Management of acquired flexural deformity of the metacarpophalangeal joint in Equidae.

Fifteen horses with flexural deformity of the metacarpophalangeal joint were evaluated and their conditions were designated as mild, moderate, or severe. Evaluations were made on the basis of clinical signs and lesions seen on radiography. Horses with mild deformities were treated with corrective trimming and shoeing; those with moderate deformities were treated with desmotomy of the accessory ligament of the deep digital flexor tendon and corrective shoeing. Desmotomies of the accessory ligaments of both deep and superficial digital flexor tendons were performed on horses severely affected, followed by corrective shoeing. In this long-term study, 4 horses with mild lesions and 4 horses with moderate lesions returned to useful work. None of the horses with severe disease responded enough to withstand strenuous athletic training.

Cystic calculi in two horses.

The use of real-time ultrasound for examination of the bladder was a useful diagnostic aid in 2 cases of cystic calculi. The ultrasound procedure revealed that a firm mass palpated per rectum in the bladder of one horse was a calculus. In the other horse, ultrasound revealed additional small uroliths. To remove the uroliths in both horses, laparocystidotomy via a ventral paramedian approach was chosen because it provided the best access to the bladder lumen. The calculi were analyzed by qualitative chemical analysis and quantitative crystallography. Results differed between analysis methods. Crystallography revealed that the mineral composition of both calculi was pure calcium carbonate. Chemical analysis erroneously indicated that the calculi contained phosphate, magnesium, and oxalate.

Laser therapy in the horse: histopathologic response.

Surgical incisions were made in the skin and superficial digital flexor tendons in horses. A low intensity laser therapy device was used to treat the limbs. After laser therapy was completed, skin and superficial digital flexor tendons from incised laser-irradiated, incised-control, and nonincised-control limbs were compared microscopically. Qualitative differences between laser irradiated and nonirradiated tissues were not found. The laser therapy device used in this study may be of insufficient power to affect wound healing.

Fatal hemolytic disease in sheep attributed to Leptospira interrogans serotype hardjo infection.

An outbreak of acute hemolytic disease in a large flock of sheep resulted in a mortality of approximately 5% in lambs. A diagnosis of Leptospira interrogans serotype hardjo infection was established on the basis of the presence of leptospires in the urine of one lamb, serologic findings in a guinea pig inoculated with this urine, L. hardjo titers in lambs, and pathologic findings. Prominent necropsy findings included severe icterus, thin watery blood, dark red to black kidneys and severe hemoglobinuria.