Photodermatitis and ocular changes in nine horses after ingestion of wild parsnip (pastinaca sativa).

BACKGROUND: Primary photosensitization rarely occurs in horses and can easily be misinterpreted. Descriptions of the disease in horses after ingestion of parsnip are lacking. The aim of this case series was to describe the dermatological and ocular changes due to photosensitization and to raise awareness of parsnip being a possible aetiologic agent. CASE PRESENTATION: Nine horses from three different stables in Berlin and Brandenburg, Germany, presented variable degrees of erythema, scaling, crusting and necrosis of unpigmented skin at the head and prepuce. Horses were of different breeds with a median age of 15 ± 5.9 years. A mild leukocytosis was diagnosed in 1/9 horses at admission. Analyzed liver enzymes were within the reference ranges in all horses. Ocular changes were diagnosed as follows: blepharitis (3/9), conjunctivitis (7/9), corneal edema without additional signs of keratitis and/or uveitis (2/9), corneal edema with signs of uveitis (1/9) and photophobia (4/9). One horse developed a fluorescein positive corneal erosion. Skin biopsy (1/9) revealed a moderate to severe acute, eosinophilic and lymphocytic dermatitis with dermal edema and vasculitis. All stables housing these patients fed hay from the same distributer. Analyzed hay samples showed high contents of wild parsnip (plants, seeds, roots). Wild parsnip is widespread in Europe and contains furocoumarins, a family of photodynamic pigments, which may cause primary photodermatitis, keratoconjunctivitis and uveitis. Horses were treated according to severity of clinical symptoms systemically with flunixine meglumine (1.1 mg/kg BW 1-2x/day) or prednisolone (1 mg/kg BW 1x/day). Topically, either gentamicin (3x/day), dexamethasone (2-3x/day) and/or atropine (1x/day) were used. Skin care was provided with almond oil or dexpanthenol (2x/day). All horses were kept in a dark environment or were treated with sunscreen and facemasks. Duration of treatment varied from 6-30 days (median 11.3 days). CONCLUSION: Ingestion of wild parsnip (Pastinaca sativa) can induce primary photosensitization with dermatitis and ocular injury in horses. In times of extreme weather, hay may alter in botanical composition, resulting in high amounts of uncharacteristic plants causing novel problems.

[Evaluation of the applanation tonometer Tono-Pen Avia® Vet™ for the measurement of the canine and feline intraocular pressure]. / Evaluation des Applanationstonometers Tono-Pen Avia® Vet™ für die Bestimmung des Augeninnendrucks bei Hunden und Katzen.

OBJECTIVE: Using tonometers, intraocular pressure (IOP) is merely measured indirectly leading to measurement inaccuracies. All available technical devices are designed for humans, hence a calibration via comparison to manometric measurements is necessary for their use in veterinary medicine. In this study, the applanation tonometer Tono-Pen Avia® Vet™ (TPA) was to be calibrated for use in dogs and cats resulting in the calculation of a correction factor. Additional objectives were the determination of reference values for TPA-derived IOP and the evaluation of possible influence of patient characteristics on measurements results. MATERIAL AND METHODS: For the manometric study, 10 enucleated eyes from cats and dogs were subject to IOP measurement with a manometer and the TPA covering the range of 5-60 mmHg. The mean percentage of difference between manometer and TPA was used to calculate correction factors. Subsequently, the TPA was employed to measure the IOP in healthy animals without signs of ocular disease for the determination of reference values. The effect of the patient characteristics age, body weight, and gender on the IOP measurement results was examined using statistical mixed models. RESULTS: With rising intraocular pressure, the TPA underestimated IOP to an increasing degree. Multiplication of the TPA-derived IOP with the factor of 1.5 for dogs and cats resulted in values well in accordance with the manometrically-derived, actual IOP. In the second part of the study, a total of 94 dogs (188 eyes) and 64 cats (128 eyes) were examined. Reference values for the IOP measured with the TPA are 9-18 mmHg for dogs and 9-20 mmHg for cats. For both species, age exhibited a significant influence (dog, p = 0.001 and cat, p = 0.008) on the IOP measurement results in that the IOP-values displayed a decrease with increasing age. CONCLUSION: The TPA underestimated the actual IOP with increasing intraocular pressure. The calculated correction factor of 1.5 is suitable for the conversion of tonometric IOP results into actual pressure values. CLINICAL RELEVANCE: The TPA is suitable for the measurement of the IOP in dogs and cats.

Consider the eye in preventive healthcare - ocular findings, intraocular pressure and Schirmer tear test in ageing cats.

OBJECTIVES: Geriatric health screening in cats is highly recommended. However, information about normal and abnormal findings is scarce, especially regarding the eyes of ageing cats. This prospective study examined the influence of the ageing process on vision and ocular structures in older cats. METHODS: A total of 209 cats (aged 9-24 years) underwent physical examination, vision assessment, slit lamp biomicroscopy and ophthalmoscopy. Systolic blood pressure (SBP) measurement, Schirmer tear test (STT) reading and rebound tonometry were performed. Systemic disease was not a criterion for exclusion. RESULTS: Vision was good in 157/209 cats (75.1%) and impaired in 52/209 cats (24.9%). Increasing age and the occurrence of vision impairment were not statistically associated ( P = 0.053). Retinal oedema, retinal haemorrhage and/or retinal detachment (19 cats) and glaucoma (12 cats) were the most common findings in vision impaired cats. Increasing age was significantly associated with the occurrence of lenticular sclerosis ( P = 0.01) and attenuated retinal vessels ( P = 0.02). Increasing age and SBP were significantly associated with the occurrence of retinal detachment, haemorrhage and oedema ( P <0.001 each). In cats without evidence of hypertensive ocular damage, younger cats had a tendency for higher SBP values than older cats, although this difference was not significant. Mean intraocular pressure (IOP) was 16.5 ± 5.0 mmHg. Age did not significantly affect the IOP values ( P = 0.54). Mean STT was 15.8 ± 4.8 mm/min. The STT was found to increase with age ( P = 0.025). CONCLUSIONS AND RELEVANCE: Although vision impairment is not a clinical sign of old age in cats, age-related changes may contribute to vision-threatening diseases. This study contributes to preventive healthcare by examining the influence of the ageing process on vision and ocular structures in older cats.

High resolution imaging of the equine cornea using the DUB®-SkinScanner v3.9. / Hochauflösende Darstellung der Hornhaut des Pferdes mit dem DUB®-SkinScanner v3.9.

OBJECTIVE: The aim was to describe the use of the DUB®-SkinScanner v3.9 (taberna pro medicum GmbH, Lueneburg, Germany) for the examination of the equine cornea. MATERIAL AND METHODS: Using the DUB®-SkinScanner v3.9 various pathological corneal conditions were pictured in the A- and B-mode at a frequency of 22 and/or 50 MHz in nine eyes of eight horses. Scans were obtained from standing horses or from horses under general anesthesia non-related to image acquisition. RESULTS: The examination allowed real time imaging and measurement of the equine cornea in vivo. Compared to slit-lamp biomicroscopy additional information was obtained in seven of nine eyes regarding the corneal thickness, in four of nine eyes regarding the epithelium, in five of nine eyes regarding the stroma and in five of nine eyes regarding the endothelium. CONCLUSION AND CLINICAL RELEVANCE: The DUB®-SkinScanner v3.9 is a valuable high-resolution imaging tool for the evaluation of the equine cornea under practice conditions. The image acquisition does not depend on corneal transparency and provides additional diagnostic information to the standard slit-lamp biomicroscopy.

LRP2 Acts as SHH Clearance Receptor to Protect the Retinal Margin from Mitogenic Stimuli.

During forebrain development, LRP2 promotes morphogen signaling as an auxiliary SHH receptor. However, in the developing retina, LRP2 assumes the opposing function, mediating endocytic clearance of SHH and antagonizing morphogen action. LRP2-mediated clearance prevents spread of SHH activity from the central retina into the retinal margin to protect quiescent progenitor cells in this niche from mitogenic stimuli. Loss of LRP2 in mice increases the sensitivity of the retinal margin for SHH, causing expansion of the retinal progenitor cell pool and hyperproliferation of this tissue. Our findings document the ability of LRP2 to act, in a context-dependent manner, as activator or inhibitor of the SHH pathway. Our current findings uncovered LRP2 activity as the molecular mechanism imposing quiescence of the retinal margin in the mammalian eye and suggest SHH-induced proliferation of the retinal margin as cause of the large eye phenotype observed in mouse models and patients with LRP2 defects.

Malignant peripheral nerve sheath tumor of the third eyelid in a 3-year-old Rhodesian Ridgeback.

A 3-year-old Rhodesian Ridgeback was presented with conjunctivitis, enlargement of the third eyelid and a dorsotemporal deviation of the right eye. A mass within the third eyelid was detected and excised. The histopathologic examination showed a malignant peripheral nerve sheath tumor, which most likely is a neurofibrosarcoma based on immunohistochemistry.

Central corneal thickness measurements and ultrasonographic study of the growing equine eye.

OBJECTIVE: The aim of this study was to determine the central corneal thickness (CCT) of healthy equine eyes with high-frequency ultrasound (HF) and ultrasound biomicroscopy (UBM) and to measure the axial dimensions with B-mode ultrasound. Additionally, the influence of the age on the measured dimensions of the globe was analyzed. ANIMALS STUDIED: Fifty warm blood horses (mean age 23.0 ± 21.12 months) were divided into 3 age groups (group 1: 0-6 months; group 2: ≥7-30 months; and group 3: ≥31-78 months). PROCEDURE: Corneal measurements were performed with a 22-MHz and a 50-MHz transducer. Crystalline lens thickness (CLT), vitreous chamber depth (VCD), and axial globe length (AGL) were measured at a frequency of 10 MHz. Anterior chamber depth (ACD) was calculated. The eyes were measured under general anesthesia nonrelated to this study. RESULTS: The mean CCT of 50 eyes was 818 ± 41 µm. The mean values ± SD in mm for axial dimensions were AGL 34.7 ± 2.7, ACD 3.4 ± 0.7, CLT 10.0 ± 0.9, and VCD of 20.4 ± 1.5. A positive correlation with increasing age was found for all dimensions. No significant differences were found between the gender and the left or right eye. CONCLUSION: HF and UBM are valuable high-resolution imaging tools for CCT measurements in horses. The here-obtained values support previous findings that a positive correlation with increasing age exists for CCT, ACD, CLT, VCD, and AGL in horse.

Toward an animal model of the human tear film: biochemical comparison of the mouse, canine, rabbit, and human meibomian lipidomes.

PURPOSE: Secretions that are produced by meibomian glands (also known as meibum) are a major source of lipids for the ocular surface of humans and animals alike. Many animal species have been evaluated for their meibomian lipidomes. However, there have been a very small number of studies in which the animals were compared with humans side by side. Therefore, the purpose of this study was to compare meibum collected from humans and three typical laboratory animals, canines, mice, and rabbits, for their meibomian lipid composition in order to determine which animal species most resembles humans. METHODS: High pressure liquid chromatography (HPLC) and gas-liquid chromatography (GLC) in combination with mass spectrometry were used to evaluate lipidomes of all tested species. RESULTS: Among three tested animal species, mice were found to be the closest match to humans in terms of their meibomian lipidomes, while canines were the second closest species. The lipids of these three species were close to each other structurally and, for most lipid classes, quantitatively. The rabbit meibomian lipidome, on the other hand, was vastly different from lipidomes of all other tested species. Interestingly, a previously described class of lipids, acylated omega-hydroxy fatty acids (OAHFA), was found to be present in every tested species as the major amphiphilic component of meibum. CONCLUSIONS: Our side by side comparison of the rabbit and the human meibum demonstrated their vast differences. Thus, the rabbit seems to be a poor animal model of the human tear film, at least when studying its biochemistry and biophysics.

Comparative HPLC-MS analysis of canine and human meibomian lipidomes: many similarities, a few differences.

The aim of this study was to evaluate the lipidome of meibomian gland secretions in canines (cMGS) - a common pet and laboratory animal - and to compare it with that of human MGS (hMGS), to determine whether canines could be used as a valid experimental animal model in studies of the biochemistry and physiology of the human ocular surface in general, and of the Meibomian glands in particular. The MGS of both species were evaluated using HPLC in combination with atmospheric pressure chemical ionization ion trap mass spectrometry. The main lipid classes found in cMGS were very long chain cholesteryl esters, wax esters, (O-acyl)-omega-hydroxy fatty acids (OAHFA), and cholesteryl esters of OAHFA. The lipidomes of cMGS and hMGS were found to be qualitatively similar, which implies similar biosynthetic and biodegradation pathways in canines and humans. However, some quantitative differences between the two were observed.