Steven R. Hollingsworth

Ivermectin‐induced blindness treated with intravenous lipid therapy in a dog

Objective To report a case of blindness due to the ingestion of ivermectin and subsequent successful treatment with intravenous lipid (IVL) therapy. Case Summary A female neutered Jack Russell Terrier was examined for acute onset of apparent blindness after being exposed to ivermectin the previous day. The dog appeared to be blind during initial examination. Pupillary light reflex, menace response, and dazzle reflex were not present in either eye. Fundic examination revealed small areas of linear retinal edema. Electroretinography (ERG) showed diminished activity in both eyes. Ivermectin was present in the serum on toxicological assay. Approximately 20 hours after exposure, IVL was infused. Within 30 minutes of initiating the infusion, the pupillary light reflexes returned in both eyes, and by the end of the infusion the patient behaved as if sighted. Fundic examination and ERG were unchanged at this time. The dog was tested for the multidrug resistance gene mutation and was unaffected. New or Unique Information Provided Ivermectin toxicity occurs in dogs with apparent blindness being a common clinical sign. This is the first case report of ivermectin-induced blindness evaluated with ERG before and after treatment with IVL in a dog unaffected by the multidrug resistance gene mutation. Treatment with an infusion of IVL therapy appeared to shorten the clinical course of disease in this patient without affecting ERG results.OBJECTIVE To report a case of blindness due to the ingestion of ivermectin and subsequent successful treatment with intravenous lipid (IVL) therapy. CASE SUMMARY A female neutered Jack Russell Terrier was examined for acute onset of apparent blindness after being exposed to ivermectin the previous day. The dog appeared to be blind during initial examination. Pupillary light reflex, menace response, and dazzle reflex were not present in either eye. Fundic examination revealed small areas of linear retinal edema. Electroretinography (ERG) showed diminished activity in both eyes. Ivermectin was present in the serum on toxicological assay. Approximately 20 hours after exposure, IVL was infused. Within 30 minutes of initiating the infusion, the pupillary light reflexes returned in both eyes, and by the end of the infusion the patient behaved as if sighted. Fundic examination and ERG were unchanged at this time. The dog was tested for the multidrug resistance gene mutation and was unaffected. NEW OR UNIQUE INFORMATION PROVIDED Ivermectin toxicity occurs in dogs with apparent blindness being a common clinical sign. This is the first case report of ivermectin-induced blindness evaluated with ERG before and after treatment with IVL in a dog unaffected by the multidrug resistance gene mutation. Treatment with an infusion of IVL therapy appeared to shorten the clinical course of disease in this patient without affecting ERG results.

Clinical and diagnostic imaging findings in dogs with zygomatic sialadenitis: 11 cases (1990-2009).

OBJECTIVE To describe clinical and diagnostic imaging features of zygomatic sialadenitis in dogs. DESIGN Retrospective case series. ANIMALS 11 dogs with zygomatic sialadenitis and 20 control dogs without evidence of retrobulbar disease. PROCEDURES Medical records were searched for dogs with zygomatic sialadenitis that underwent some combination of magnetic resonance imaging (MRI), computed tomography (CT), and ultrasonography. Signalment, clinical signs, results of clinicopathologic tests, cytologic and histologic diagnosis, treatment, qualitative disease features, and disease course were recorded. Images obtained via MRI or CT were analyzed for pre- and postcontrast signal intensity or density, respectively; zygomatic salivary gland area was determined. Results were compared with those of control dogs that underwent the same imaging procedures (n = 10/method). Ultrasonographic images of affected dogs were assessed qualitatively. RESULTS Most (9/11) affected dogs were medium- or large-breed males (mean age, 8 years) with unilateral disease. Affected dogs had clinical signs of retrobulbar disease and cytologic or histologic evidence of zygomatic sialadenitis. Sialoceles were detected in 7 affected glands. Compared with values for control dogs, MRI findings in affected dogs (n = 7) included gland enlargement, T1-weighted hypointensity, T2-weighted hyperintensity, and increased contrast enhancement; CT features in affected dogs (2) included gland enlargement and hypodensity on unenhanced images. Retrobulbar masses were identified via ultrasonography in 9 of 10 orbits examined, and zygomatic salivary gland origin was detected in 4. CONCLUSIONS AND CLINICAL RELEVANCE Visualization of anatomic structures for diagnosis of zygomatic sialadenitis and evaluation of adjacent structures was excellent via MRI and CT Ultrasonography was less definitive but useful for sample collection.

Equine keratomycoses in California from 1987 to 2010 (47 cases)

REASONS FOR PERFORMING STUDY Equine keratomycosis in the western USA has received little study, probably owing to its low prevalence. OBJECTIVES To determine clinical features, predominant fungal isolates, treatment modalities and outcomes of horses with keratomycosis in California and compare these with results from different geographic regions. METHODS Records of horses presented to the University of California-Davis Veterinary Medical Teaching Hospital (UCD-VMTH) with confirmed keratomycosis between 1987 and 2010 were reviewed for this retrospective study. Information retrieved from the record included background, ophthalmic examination findings, treatment prior to and following presentation, visual outcome, and ocular survival. RESULTS A total of 48 eyes in 47 horses met the inclusion criteria and comprised 2% of cases presented to the UCD-VMTH ophthalmology service. Prior to presentation, 20 horses (43%) received at least one topically administered anti-inflammatory medication. Keratomycosis was confirmed by fungal culture in 38 horses (81%), by histopathology in 2 horses (4%) and by cytology in 7 horses (15%). Forty-four isolates were identified in the 38 horses cultured; Aspergillus was the most common isolate (64%) and a novel isolate, Papulospora, was identified in 2 horses. Treatment consisted of medication only (73%), medical and surgical treatment (25%), or immediate enucleation (2%). Globe retention was 77% and vision retention was 53%. Corneal perforation was significantly associated with loss of vision (P<0.001). CONCLUSIONS Keratomycosis is relatively uncommon in horses presented for ophthalmic conditions at UCD-VMTH. Corneal perforation was a negative prognostic indicator for vision in this population of northern Californian horses.

Equine Degenerative Myeloencephalopathy in Lusitano Horses

BACKGROUND Equine degenerative myeloencephalopathy (EDM) is a neurodegenerative disorder that has been previously associated with low vitamin E concentrations. OBJECTIVE To describe the clinical, electrophysiologic, and pathologic features of EDM in a group of related Lusitano horses. ANIMALS Fifteen Lusitano horses. PROCEDURES Neurologic examinations were conducted, and serum vitamin E concentrations were measured. Three neurologically abnormal horses were further evaluated by ophthalmologic examination, electroretinography, electroencephalography, muscle and nerve biopsies, and post-mortem examination. RESULTS Six horses appeared neurologically normal, 6 were neurologically abnormal, and 3 had equivocal gait abnormalities. Abnormal horses demonstrated ataxia and paresis. An inconsistent menace response was noted in 4 neurologically abnormal horses and in 1 horse with equivocal findings. All horses had low serum vitamin E concentrations (<1.5 ppm). Ophthalmologic examinations, electroretinograms, electroencephalograms, and muscle and peripheral nerve biopsies were unremarkable in 3 neurologically abnormal horses. At necropsy, major neuropathological findings in these horses were bilaterally symmetric, severe, neuro axonal degeneration in the gracilis, cuneatus medialis, cuneatus lateralis, and thoracicus nuclei and bilaterally symmetric axonal loss and demyelination mainly in the dorsolateral and ventromedial tracts of the spinal cord. A diagnosis of EDM was made based on these findings. Pedigree analysis identified 2 sires among the affected horses. CONCLUSIONS AND CLINICAL RELEVANCE Equine degenerative myeloencephalopathy is a neurodegenerative disorder that causes ataxia and, in severe cases, paresis, in young Lusitano horses. The disease appears to have a genetic basis, and although vitamin E deficiency is a common finding, low serum vitamin E concentrations also may occur in apparently unaffected related individuals.

INTRAOCULAR PRESSURE IN CAPTIVE AMERICAN FLAMINGOS (PHOENICOPTERUS RUBER) AS MEASURED BY REBOUND TONOMETRY

Abstract:  Intraocular pressure was measured using rebound tonometry in American flamingos (Phoenicopterus ruber), with the head in an upright standing position and when lowered in a feeding position, to establish a reference range. Mean ± standard deviation (SD) (range) intraocular pressure for flamingos with the head in an upright position was right eye (OD) = 10.9 ± 1.8 mm Hg (7–15 mm Hg) and left eye (OS) = 11.1 ± 2.3 mm Hg (8–21 mm Hg). Median intraocular pressure for flamingos with the head in an upright position was OD and OS = 11 mm Hg. Mean intraocular pressure for flamingos with the head in a feeding position was OD = 14.3 ± 2.5 mm Hg (10–22 mm Hg) and OS = 14.4 ± 2.7 mm Hg (11–24 mm Hg), which were significantly higher. Median intraocular pressure for flamingos with the head in a feeding position was OD and OS = 14 mm Hg.

Detection of equine herpesvirus in horses with idiopathic keratoconjunctivitis and comparison of three sampling techniques.

OBJECTIVES To determine the role of equine herpesvirus (EHV) in idiopathic keratoconjunctivitis in horses and to determine whether sample collection method affects detection of EHV DNA by quantitative polymerase chain reaction (qPCR). ANIMALS STUDIED Twelve horses with idiopathic keratoconjunctivitis and six horses without signs of ophthalmic disease. PROCEDURES Conjunctival swabs, corneal scrapings, and conjunctival biopsies were collected from 18 horses: 12 clinical cases with idiopathic keratoconjunctivitis and six euthanized controls. In horses with both eyes involved, the samples were taken from the eye judged to be more severely affected. Samples were tested with qPCR for EHV-1, EHV-2, EHV-4, and EHV-5 DNA. Quantity of EHV DNA and viral replicative activity were compared between the two populations and among the different sampling techniques; relative sensitivities of the sampling techniques were determined. RESULTS Prevalence of EHV DNA as assessed by qPCR did not differ significantly between control horses and those with idiopathic keratoconjunctivitis. Sampling by conjunctival swab was more likely to yield viral DNA as assessed by qPCR than was conjunctival biopsy. EHV-1 and EHV-4 DNA were not detected in either normal or IKC-affected horses; EHV-2 DNA was detected in two of 12 affected horses but not in normal horses. EHV-5 DNA was commonly found in ophthalmically normal horses and horses with idiopathic keratoconjunctivitis. CONCLUSIONS Because EHV-5 DNA was commonly found in control horses and in horses with idiopathic keratoconjunctivitis, qPCR was not useful for the etiological diagnosis of equine keratoconjunctivitis. Conjunctival swabs were significantly better at obtaining viral DNA samples than conjunctival biopsy in horses in which EHV-5 DNA was found.

Inheritance of cataracts and primary lens luxation in Jack Russell Terriers.

OBJECTIVE To characterize heritability and mode of inheritance of cataracts and primary lens luxation in Jack Russell Terriers. ANIMALS 872 Jack Russell Terriers from which buccal epithelial cells were collected and phenotypes for cataracts and lens luxation were determined and an additional 1,898 Jack Russell Terriers without phenotypic information used to complete pedigree relationships and that were included in the analyses. PROCEDURES Narrow-sense heritabilities and genetic correlation for cataracts and lens luxation were modeled by use of threshold analysis, whereas complex segregation analysis was used to characterize mode of inheritance. For the analyses, dogs < 6 years old, unless confirmed as having cataracts or lens luxation, were classified as an unknown phenotype. The possible involvement of an HSF4 mutation in cataracts was determined by DNA sequencing. RESULTS Cataracts and primary lens luxation were highly heritable and genetically correlated, and neither was controlled by a single gene. Cataracts were not associated with an HSF4 mutation. CONCLUSIONS AND CLINICAL RELEVANCE Analysis of the data indicated that concerted selection against both cataracts and primary lens luxation when choosing breeding animals can be used to improve ocular health in Jack Russell Terriers.

Corneal surgical techniques

Although challenging from a technical perspective, many corneal surgical procedures can be mastered by the general practitioner. This article describes a number of procedures that can potentially save both the eye and vision. Procedures include corneal laceration repair, conjunctival pedicle graft, tarsoconjunctival island graft, advancement graft, total conjunctival graft, frozen tectonic corneal graft, porcine small-intestine submucosa graft, and superficial keratectomy. In addition to considerations on how to properly perform these procedures, emphasis is placed on common causes of failure and how to avoid them.

Distribution and outcome of ocular lesions in snakes examined at a veterinary teaching hospital: 67 cases (1985–2010)

OBJECTIVE To determine the distribution and clinical outcome of ocular lesions in snakes. DESIGN Retrospective case series. ANIMALS 67 snakes with ocular lesions. PROCEDURES Signalment, lesion duration, diagnosis, treatment, and clinical outcome were recorded for all snakes with ocular lesions that were examined at a veterinary teaching hospital from 1985 to 2010. RESULTS 71 ocular lesions were detected in 67 of 508 (13%) snakes examined. Affected snakes were of the families Boidae, Pythonidae, Colubridae, and Viperidae. The distribution of ocular lesions did not vary by taxonomic family, age, or sex; however, snakes from the genus Epicrates with ocular lesions were overrepresented in the population. The most commonly diagnosed ocular lesions were retained spectacle (n = 41), pseudobuphthalmos or subspectacular abscess (13), trauma (8), and cataracts (4). Pseudobuphthalmos or subspectacular abscess developed more frequently in Colubridae than in non-Colubridae snakes. Of the 16 snakes with retained spectacles for which data were available, the lesion recurred once in 4 snakes and multiple times in 5 snakes. CONCLUSIONS AND CLINICAL RELEVANCE Results indicated that retained spectacle was the most common ocular lesion diagnosed in snakes. Compared with other snakes with ocular lesions, snakes of the genus Epicrates had a higher than expected frequency of ocular lesions in general and snakes of the family Colubridae had a higher than expected frequency of pseudobuphthalmos or subspectacular abscess.

Electrophysiological studies in American Quarter horses with neuroaxonal dystrophy.

OBJECTIVE Neuroaxonal dystrophy (NAD) is a disease characterized by the sudden onset of neurologic signs in horses ranging from 4 to 36 months of age. Equine degenerative myeloencephalopathy (EDM), a disease that has been associated with low vitamin E concentrations, is considered a more advanced form of NAD. The objective of this report is to describe the electrophysiological features of NAD/EDM in American Quarter horses (QHs). HORSES: Six NAD/EDM-affected QHs and six unaffected QHs were evaluated by ophthalmic examination and electroretinography. Five of the NAD/EDM-affected QH and five unaffected QHs were also evaluated by electroencephalography (EEG). RESULTS Ophthalmic examination, ERGs, and EEGs were unremarkable in NAD/EDM cases. CONCLUSIONS Neuroaxonal dystrophy/EDM does not appear to cause clinical signs of ocular disease or functional ERG/EEG deficits in QHs.