Raccoon ascarid larvae (Baylisascaris procyonis) as a cause of ocular larva migrans.

Larvae of the common raccoon roundworm, Baylisascaris procyonis, are known causes of visceral larva migrans and CNS disease in animals and human beings. In the present experiments we examined the ability of B. procyonis to cause ocular larva migrans (OLM) in subhuman primates, as an indication of its possible ocular zoonotic importance. Squirrel monkeys given 5,000 or 10,000 infective B. procyonis eggs per os and cynomolgus monkeys given 20,000 eggs had clinical and histologic evidence of OLM, beginning 7 days after inoculation. Clinically, multifocal retinal hemorrhages, white spots, chorioretinitis, inflammatory tracks, vascular sheathing, diffuse retinal degeneration, and motile intraretinal larvae were seen. Histologically, primarily subretinal larvae caused varying degrees of retinal disruption, degeneration and necrosis, retinitis, vasculitis, and perivascular sheathing, primarily with eosinophils. Larvae were also present in choroidal granulomas. It was concluded that B. procyonis larvae have marked ability to produce OLM in subhuman primates following oral infection and should be considered as a possible etiology in human ocular disease.

Neonatal exposure to D,L-2-amino-3-phosphonopropionate (D,L-AP3) produces lesions in the eye and optic nerve of adult rats.

Metabotropic glutamate receptors are a recently described receptor class with emerging importance in synaptic plasticity and brain development. Activation of metabotropic glutamate receptors results in several cellular secondary messenger events that are especially important during postnatal development. This study characterized the effects of D,L-2-amino-3-phosphonopropionate (D,L-AP3), an aspartic acid analog with agonist and antagonist activity at the metabotropic receptor, on the postnatal development of the rat eye and optic nerve. Sprague-Dawley rat pups were treated daily (i.p.) with saline or 500 mg/kg D,L-AP3 on postnatal days (PND) 4-10 or 10-14. After making clinical and ophthalmoscopic examinations, rats were necropsied between 65 and 70 days of age and light microscopic evaluations were made of eyes and optic nerves. Between postnatal days 10-20, all treated rats exhibited motor tremors, circling, and head tilt. Ophthalmoscopic lesions were more severe in rats treated on days 4-10 than days 10-14 and included decreased retinal vasculature, cataracts, and retinal dysplasia, hypoplasia, and detachment. All rats treated on days 4-10 had severe optic nerve atrophy/hypoplasia grossly and severe retinal atrophy, retinal detachment, and cataracts histologically. Seven of eight rats treated on days 10-14 had qualitatively similar but less severe lesions. Overall, rats treated with D,L-AP3 on PND 4-10 had earlier and more severe retinal and optic nerve lesions when compared to rats treated on PND 10-14. These data characterize the morphologic effects in adult rats exposed to D,L-AP3 as neonates and suggest a possible role for the metabotropic receptor in the postnatal development of retina and optic nerve.

Effects of flunixin meglumine and dexamethasone on aqueous protein values after intraocular surgery in the dog.

Effects of flunixin meglumine and/or dexamethasone on aqueous protein concentrations were evaluated in dogs during and after intraocular surgery. Flunixin meglumine plus dexamethasone had the greatest inhibitory effect on postoperative aqueous protein increases with 64.2% inhibition over base-line aqueous protein values 24 hours after surgery. Dexamethasone alone had a 45.6% inhibition and flunixin meglumine alone had a 22.4% inhibition. Treatment with these drugs separately or in combination had a marked effect in decreasing postoperative inflammation.

Effects of cyclocryosurgery on the clinically normal canine eye.

Four cyclocryosurgical procedures were compared for effects on normal canine eyes. All procedures produced a significant (P less than 0.05) decrease in intraocular pressure, a marked uveitis, ciliary epithelial cell loss, edema and engorgement of the ciliary processes, iris necrosis, protein effusion, chemosis, and mild discomfort, as indicated by mild blepharospasm and slight epiphora. The histopathologic changes were evaluated at 5 minutes, 1 week, 1 month, and 6 months after surgery. The ciliary epithelium was normal in appearance and intraocular pressure had returned to the normal range at 6 months after surgery. The adverse reactions to the cyclocryosurgical procedures included retinal detachments, chemosis, conjunctivitis, transient increased intraocular pressure, uveitis, iris depigmentation, and corneal granulation tissue.

Ciliary body temperatures during cyclocryotherapy in the clinically normal dog.

Three cryosurgical units were compared on the basis of the ability of each unit to freeze the ciliary body of enucleated normal canine eyes. The coldest average temperatures reached were -13.4 C, -4.3 C, and -17.6 C. One of the units was then used to freeze the ciliary body in the left eye of 25 dogs for 5 minutes. Ciliary body temperatures were monitored every 15 s during cyclocryosurgery. In 18 eyes in situ, the coldest average temperature reached was -13.4 C. In 7 proptosed globes, the coldest average temperature reached was -13.8 C. The results were not significantly different (P less than 0.05). The effects of the cryosurgery and centesis procedure were monitored daily by direct observation and Schiotz's tonometry. Histologic changes from the procedure were evaluated at 5 minutes, 1 week, 1 month, and 6 months after surgery. Intraocular pressure returned to the normal range within 1 to 2 weeks, the anterior uveitis subsided in 7 to 10 days, and ciliary body epithelium was histologically normal within 6 months after surgery.

Ocular, naso-maxillary, and neural anomalies in raccoons, Procyon lotor (L.).

Congenital ocular and related anomalies were studied in two unrelated young raccoons. One animal was anophthalmic and had severe anomalies of the central nervous system, consisting of meningoencephalocele, pachygyria, hydranencephaly, cerebellar cavitation, syringomyelia, and other defects. A second animal was microphthalmic with congenital defects of the nose, maxilla and teeth. Ocular lesions were severe and included chorioretinal coloboma, retinal folds, disorganized neuroectodermal cell layers, spherophakia, cataract and other defects. The nose had unilateral abnormal epithelium, hair follicles, sweat glands and sebaceous glands, and a lack of parietal cartilage on the affected side.

Decreased tear production associated with general anesthesia in the dog.

Schirmer I tear tests were done on 20 dogs before and during general anesthesia. Atropine sulfate reduced tear production from a mean base-line value of 20.35 +/- 3.33 mm/minute to 14.10 +/- 6.13 mm/minute, 10 minutes after its subcutaneous administration. The combination of subcutaneous atropine, intravenous thiamylal sodium, and inhalation anesthesia reduced tear production to a mean value of 0.53 +/- 1.12 mm/minute at 60 minutes after induction.

Use of cyclocryotherapy in management of glaucoma in dogs.

In 5 cases of glaucoma (2 from trauma, 2 from narrowed drainage angles, 1 secondary to lens extraction), cyclocryotherapy was used to control intraocular pressure. In all cases the intraocular pressure decreased, with the usual result being a cosmetic and painless but blind eye.

Changes in intraocular pressure and pupil size following intramuscular administration of hydromorphone hydrochloride and acepromazine in clinically normal dogs.

OBJECTIVE: To investigate the effects of intramuscularly administered hydromorphone hydrochloride and acepromazine on intraocular pressure (IOP) and pupil size (PS). ANIMALS STUDIED: Seventeen dogs free of clinically relevant ocular abnormalities. PROCEDURE: Measurements of IOP and PS were obtained and the dogs were injected intramuscularly with hydromorphone (0.04-0.08 mg/kg) and acepromazine (0.04 mg/kg). Measurements of IOP and PS were repeated 10 min and 25 min later. RESULTS: Though a decreasing trend in IOP values was demonstrated, no significant difference was noted in IOP from the initial examination to examination following intramuscular administration of hydromorphone and acepromazine. Significant miosis was present in 16 of 17 dogs at 10 min and 25 min following administration of hydromorphone and acepromazine. CONCLUSION: Hydromorphone (0.04-0.08 mg/kg) and acepromazine (0.04 mg/kg) cause significant miosis in dogs at 10 and 25 min following intramuscular administration.

The raccoon ascarid. A probable cause of human ocular larva migrans.

The ability of raccoon roundworm larvae, Baylisascaris procyonis, to produce ocular larva migrans (OLM) was studied in various experimental animals. In addition, the clinical and pathologic lesions were compared to those in suspected cases of human ocular baylisascariasis, in patients with diffuse unilateral subacute neuroretinitis (DUSN). Ocular larva migrans was produced in squirrel monkeys, cynomolgus monkeys, mice, hamsters, grey squirrels, and woodchucks orally infected with B. procyonis eggs. The clinical and histologic lesions were primarily those of retinitis, retinal hemorrhages, retinal tracks, disruption, and vasculitis; pigment migration; choroiditis; vitritis; and free or encysted larvae in ocular and extraocular tissues. The lesions of experimental OLM correlated well with those of suspected cases of human ocular baylisascariasis and DUSN. Based on these studies, B. procyonis of raccoons should be considered as a probable cause of OLM and DUSN in humans.