Evaluation of glutamate loss from damaged retinal cells of dogs with primary glaucoma

OBJECTIVE: To determine whether retinal damage in dogs with primary glaucoma (PG) is consistent with ischemia-induced glutamate toxicosis. SAMPLE POPULATION: Retinal tissue sections from 25 dogs with PG and 12 normotensive control dogs. PROCEDURE: Retinal sections from control and glaucomatous dogs were stained for morphometric and terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling (TUNEL) analyses to determine whether retinal damage was consistent with glutamate toxicosis. Immunohistochemical analysis was performed to detect ischemia-like loss of glutamate from neurons in damaged areas. RESULTS: In severely damaged glaucomatous retinas, all neurosensory layers had focal regions that were thin or disrupted. There was less thinning of the outer nuclear layer (ONL) and inner nuclear layer (INL) in moderately damaged retinas than in severely damaged retinas. Acute signs of damage in the INL included cells with dark, condensed chromatin and lightly stained cytoplasm interspersed with a few TUNEL-positive cells, which was consistent with glutamate toxicosis. Glutamate immunoreactivity was reduced in thin areas and in damaged cells of the INL and ONL, which was consistent with glutamate release in damaged areas. Glutamate immunoreactivity was increased in putative Müller cells in damaged areas, which also was consistent with glutamate release. CONCLUSIONS AND CLINICAL RELEVANCE: Retinal damage in dogs with PG differs in intensity in focal areas. Damage in affected regions resembles damage induced by glutamate. Glutamate is lost from damaged neurons and accumulates in Müller cells, which is consistent with increased glutamate release contributing to the damage. Glutamate antagonists may protect INL cells in dogs with glaucoma.     

Effectiveness of α-tocopherol and selenium supplements in preventing lupinosis-associated myopathy in sheep

Objective To compare the effectiveness of combined selenium and α-tocopherol acetate treatments in preventing lupinosis-associated myopathy in sheep.
Design Measurement of plasma muscle and liver enzymes, and histopathological examination of muscle and liver in the treatment groups.
Procedure The treatments were: subcutaneous injections of selenomethionine and vitamin E (sc(SeM+E)) , an intraruminal selenium pellet and oral doses of vitamin E and intramuscular injections of selenomethionine combined with either oral doses of vitamin E (imSeM+orE) or intramuscular injections of vitamin E in an oily carrier. Another group received no supplements, while a control group was given selenium pellets on day 0 and fortnightly oral doses of vitamin E from day 0 to 72. To produce lupinosis-associated myopathy, the sheep were fed a diet low in vitamin E and given repeated injections of a crude extract of Diaphorthe toxica. Groups sc(SeM+E) and imSeM+orE were stressed by dosing with protected polyunsaturated fatty acids from day 56 onwards.
Results Lupinosis-associated myopathy was induced in all unsupplemented sheep. In these sheep the storage of Se increased and that of vitamin E decreased. The subcutaneous treatment was highly effective in preventing lupinosis-associated myopathy and also produced the highest vitamin E concentrations in plasma and liver. Supplemental vitamin E was more efficacious than supplemental Se. Concentrations of vitamin E in the livers of sheep given intramuscular vitamin E were higher than expected based on plasma concentrations. Oral doses of vitamin E proved the least effective method of increasing concentrations in liver. Lupinosis did not affect Se concentrations in liver or muscle.
Conclusion The sc(SeM+E) treatment is highly effective in preventing lupinosis-associated myopathy but needs to be further assessed when selenium and vitamin E are both limiting in the diet.     

Idiopathic ocular and nasal granulomatous inflammatory disease in a dog

A young female Akita presented for ocular and nasal lesions. Examination showed bilateral 360 degree limbal masses that extended onto the peripheral cornea. In addition, intranasal granulomatous masses were observed by rhinoscopy. Histopathologic examination with immunohistochemical staining showed that these masses were almost identical and were classified as an idiopathic, T-cell rich, granulomatous inflammation. The dog responded well to anti-inflammatory medication and the disease remains in remission 2 years after the initial presentation.     

Percutaneous retrieval of a jugular catheter fragment from the pulmonary artery of a foal

A 49-kg (107.8-lb) sexually intact male Arabian foal was evaluated at 3 days of age because of profuse watery diarrhea, anorexia, and signs of abdominal pain. Physical examination findings were unremarkable except for evidence of diarrhea. A catheter was placed in the right jugular vein for administration of antimicrobials and lactated Ringer's solution. The foal was discharged with instructions to the owner to continue antimicrobial administration and fluid therapy; at home, the owner inadvertently cut the catheter at the level of the hub during attempted removal, and the catheter fragment migrated distally in the jugular vein and subsequently lodged in the pulmonary artery. The foal was readmitted to the hospital for retrieval of the fragment, using a percutaneous retrieval technique. Catheter fragmentation is a well-recognized risk of catheterization in horses. Catheter fragments can be retrieved somewhat easily from the jugular vein; however, if the fragment migrates to the heart or pulmonary artery, imaging the fragment to locate and retrieve it can be difficult. Complications associated with catheter fragmentation include septicemia, endocarditis, lung abscesses, pulmonary embolism, dysrhythmias, cardiac perforation, pulmonary or caval thrombosis, and death. To our knowledge, this is the first report of successful retrieval of a catheter fragment from the pulmonary artery in a horse.     

Intraocular pressure in normal llamas (Lama glama) and alpacas (Lama pacos)

Objective: To determine the mean intraocular pressure in llamas ( Lama glama ) and alpacas ( Lama pacos ) using applanation tonometry. Animals studied: Ten llamas and 10 alpacas. Procedures: Intraocular pressure (IOP) was measured with a Tono-Pen™ XL (Mentor Ophthalmics, Inc., Norwell, MA, USA). Three values, with 5% variance, were recorded for each eye. Least-squares means were determined for IOP for each eye of llamas and alpacas. Controlling for age, differences between left and right eye were analyzed using anova . Two age groups were established, less than 5 years and greater than 5 years. The effect of age on IOP within each group was analyzed by linear regression. Probability values of less than 0.05 were considered significant. Results: Comparison of mean IOP between right ( n  = 20) and left eyes ( n  = 20), independent of species type, showed no differences in IOPs for llamas and alpacas. Mean IOP declined with increasing age in llamas and alpacas. Mean IOPs for 20 eyes in 10 llamas was 16.96 ± 3.51 mmHg. Mean IOP for 20 eyes in 10 alpacas was 16.14 ± 3.74 mmHg. Mean IOP for all eyes ( n  = 40), independent of species, was 16.55 ± 3.55 mmHg. The range of IOP in normal llamas and alpacas within 2 SD (95% of the population) was 14.89±18.21 mmHg. Conclusions: There was no significant difference in IOP between alpacas and llamas. Mean IOP in both species decreased with increased age.