Neonatal ophthalmology

This discussion of normal and abnormal findings on routine ophthalmic examination of the foal should prove useful to the equine practitioner who must provide counsel to the concerned owner and/or breeder. Early diagnosis and treatment of ocular abnormalities improve the prognosis for continued function and aid determination of the significance of lesions observed in later life.     

Normal equine ocular anatomy and eye examination.

When compared with small domestic animals, the horse has unique ocular characteristics (complete bony orbit, well-developed eyelid muscles, a nasal and temporal gray limbal line, granulae iridica, paurangiotic fundus). Knowledge of normal equine ocular anatomy is essential for ocular lesion interpretation. It is important to obtain a full history and general examination before sedation, nerve blocks, or other diagnostic ophthalmic tests are performed. All ocular examinations should include a systematic evaluation of both the anterior and posterior segments. Selection of other diagnostic tests depends on information obtained from the history, general inspection, and ophthalmic examination. The appropriate order of performing various special diagnostic tests must be considered before beginning the examination. If a diagnosis is elusive, referral to an ophthalmologist for further diagnostics should be considered.     

Examination of the equine foot.

The examination of the foot must be based on observations of the hoof, followed by a careful determination of areas of pain. This must be followed by an assessment of the biomechanical forces on the hoof and limb. Finally, imaging gives insight into the nature of the injury and allows the examiner to prognosticate the outcome.     

Ophthalmological findings in a closed herd of Lipizzaners

Reasons for performing the study: There are no studies on the ophthalmic health status in the Lipizzaner breed. Objective: To perform an ophthalmological survey in a closed herd in 3 housing systems. Materials: All horses at the Federal Stud Piber, Heldenberg and the Spanish Riding School Vienna were subjected to ophthalmological examination. Findings were documented and correlated with factors such as age, gender, location and housing situation. The interrelation of abnormalities of different regions was determined by calculating accuracy. Pedigree analysis of horses affected by cataract was performed. Results: A total of 267 horses met the inclusion criteria of this study. Of these, 172 horses were stabled in Piber, 72 in Vienna and 23 in Heldenberg. Ophthalmological examination revealed 203 cases with ocular findings, predominantly involving the conjunctiva (44.6%), cornea (21.7%) and fundus (37.5%). In 24 (8.9%) horses a diagnosis of cataract was made. There was no interrelation between different eye diseases. Horses stabled at Piber were significantly more affected by conjunctival and fundic abnormalities. Fewer abnormalities were found in horses stabled in open boxes. Access to free stalls resulted in more cases of conjunctivitis. Pedigree analysis showed no evidence of inbreeding as a cause of cataract formation. Conclusion and potential relevance: Acquired corneal abnormalities were over‐represented in this study. This survey may serve as a basis for further research on the pathogenesis of ophthalmic diseases in Lipizzaners.     

Medical evaluation of the eye relevant to purchase.

Performance and pleasure horses depend upon their ability to see and assess the environment. Thus, the veterinarian must be able to examine the eyes and recognize abnormalities so that the owner or purchaser can be informed about the visual status and prognosis for the horse's vision. If the veterinarian encounters suspicious or abnormal findings during the examination, a more detailed examination and/or referral to a veterinary ophthalmologist can be recommended to the owner or purchaser.     

Common Ophthalmic Problems in Pet Rabbits

As rabbits are becoming more popular as pets and owners are willing to pay for specialized care, veterinary practitioners are required to maintain their expertise treating these animals. In recent years, ophthalmic patients have become an important part of the small mammal pet population. Ocular disorders in pet rabbits can be caused by genetic defects, congenital malformations, traumatic events, infections, housing conditions, and nutritional deficiencies. Knowledge of the species-specific anatomy and physiology forms the basis for the interpretation of findings and prevents misinterpretation of a normal state as an abnormality. The ophthalmic examination of rabbits should adhere to the same principles and techniques used for canine and feline patients, although adjustments are required because of different anatomical and physiologic features. Magnification is necessary for accurate assessment. This article summarizes the common ophthalmic disorders of pet rabbits, especially those that are unique to rabbits.     

Bone marrow biopsy and evaluation

Bone marrow evaluation provides valuable diagnostic and prognostic information about neoplastic, metabolic, and inflammatory diseases. Bone marrow biopsies should be done only after examination of peripheral blood, to avoid performing unnecessary biopsies. A blood sample should be taken at the time of the bone marrow biopsy, for complete hematopoietic evaluation. It is preferable to take both an aspiration and core biopsy simultaneously. A good sample is mandatory for accurate evaluation and interpretation. The method of evaluation should be systematic, complete, and cover the following points: adequacy of specimens; estimation of cellularity; identification of number, maturation pattern, and morphology of megakaryocytes, myeloid cells, and erythroid cells; estimation of M:E ratio; and identification of abnormal cells, cellular reactions, infectious agents, or abnormal stromal reactions. Bone marrow findings should be interpreted in conjunction with signalment, history, physical findings, and laboratory results. Reference or institutional laboratories should be contacted for proper handling of bone marrow specimens for special procedures, such as histopathology, cytochemistry, immunopathology, and electron microscopy.     

Ophthalmic findings in a septic calf with the concurrent exhibition of meningitis and endophthalmitis

The aim of this study was to evaluate the impacts of ophthalmic findings obtained from both macroscopic examination and ocular ultrasonography when diagnosing bovine endophthalmitis. A newborn crossbreed (Japanese black and Holstein breeds) calf was suspected of visual impairment and central nervous system (CNS) symptoms, such as decreased activity and weak drinking performance. This calf was found to display macroscopic signs, such as clouded lens, convergent strabismus, and horizontal nystagmus, in both eyes. On ocular ultrasonography of both eyes, a V-shaped, thickened, hyperechoic structure was present in the anechoic vitreous humors, indicating retinal detachment. The animal died 4 days after the examination. Sepsis was evident in this case, as Escherichia coli was isolated from multiple organs. The autopsy and histological examination revealed meningitis, encephalitis, and secondary hydrocephalus in the CNS, and endophthalmitis and retinal detachment in both eyes. In this case, the ophthalmic findings did not provide definitive evidence for a diagnosis of endophthalmitis. However, this study indicated that retinal detachment might be an ultrasonographic finding that is suggestive of bovine endophthalmitis.     

Tracheobronchoscopy

Fiberoptic tracheobronchoscopy is a safe and rewarding technique for the diagnosis and management of a wide spectrum of respiratory tract diseases. A nomenclature system has recently been developed that allows the systematic identification of canine endobronchial anatomy during bronchoscopy. This system results in an improved ability to communicate bronchoscopic findings and provides a basis for performing a thorough bronchoscopic examination. Complications of tracheobronchoscopy are uncommon, but patients must be carefully monitored during the procedure because complications may be severe and life-threatening when they occur. Special techniques enhance the diagnostic spectrum of bronchoscopy and include brush cytology, forceps biopsy, bacterial culture, transbronchial lung biopsy, transbronchial needle aspiration, and bronchoalveolar lavage.     

Corneal stromal sequestration and keratoconjunctivitis sicca in a horse

A 19-year-old Shetland pony presented with unilateral ocular discomfort and abnormal ocular appearance. Keratoconjunctivitis sicca, ulcerative keratitis and brown discoloration of the corneal stroma were identified on ophthalmic examination. The etiology of keratoconjunctivitis sicca was not determined in this case. For practical and financial reasons, the owners requested enucleation of the affected eye. Histopathologic examination revealed extensive loss of corneal epithelium overlying a zone of hypereosinophilic, degenerate, and necrotic corneal stroma. This well-circumscribed region of corneal stromal sequestration was surrounded by stromal vascularization, and an intense inflammatory, predominantly polymorphonuclear, cellular infiltrate. The clinical and histopathologic features of this case were considered remarkably similar to those observed in feline corneal stromal sequestration.     

Advances in echocardiography.

Echocardiography is an exceptionally useful technique for diagnosing cardiovascular disease in small animals. It is noninvasive and provides a wealth of data concerning cardiac morphology and function. For many patients, echocardiography is the definitive diagnostic tool. A well-performed study coalesces the findings of the physical examination, electrocardiogram, and radiographs into a clearly defined diagnosis on which treatment decisions can be based. More so than other diagnostic techniques, echocardiography is highly operator dependent and relies on the proper acquisition and interpretation of results by an examiner who is familiar with the principles, capabilities, and limitations of ultrasound imaging.This article reviews the basics of echocardiography, measurement of cardiac dimensions, and assessment of cardiac function. Within these sections, emerging technologies that expand the capabilities of the echocardiographic examination are introduced.     

Equine ophthalmic examination: Routine diagnostic techniques

A complete, thorough ophthalmic examination is essential in the clinical approach to equine ocular diseases. In the majority of cases and more than in most systems, an ophthalmic diagnosis can be achieved at the time of examination because most ocular structures can be visualised either directly or indirectly. This article describes examination protocol and the techniques, instruments and diagnostic procedures currently available to equine general practitioners.     

Endoscopic removal of a molariform supernumerary intranasal tooth (heterotopic polyodontia) in a horse

CASE DESCRIPTION: A 3-year-old Thoroughbred mare was evaluated because of abnormal upper respiratory tract sounds (that had become apparent during race training) of 3 to 4 months' duration. CLINICAL FINDINGS: On initial physical evaluation, there were no abnormal findings. During trotting, an abnormal upper airway expiratory sound was audible. Endoscopic examination revealed a small mass protruding into the right ventral nasal meatus. Radiographic images of the skull revealed no abnormal findings. Computed tomography of the head revealed an abnormal structure in the same location as the mass that was observed during endoscopy. The x-ray attenuation of the mass was identical to that of dental tissue. TREATMENT AND OUTCOME: The mass was surgically removed with endoscopic guidance. On gross examination, the excised mass appeared to be a nearly normal molariform tooth. Histologic examination revealed that it was a well-formed tooth, with no other associated cellular populations. The mass was determined to be a molariform supernumerary intranasal tooth. Six months following discharge from the hospital, the trainer reported that the abnormal respiratory tract sound was no longer audible. During a follow-up endoscopic examination performed at the training facility, no abnormalities were detected. CLINICAL RELEVANCE: In horses, an intranasal tooth should be considered as a differential diagnosis for expiratory stridor. Clear definitions of heterotopic polyodontia, dentigerous cyst, and temporal teratoma can be used to clinically diagnose these separate anomalies. In the horse of this report, computed tomographic findings contributed to determination of a diagnosis and formulation of a treatment plan.     

Clinical utility of a complete diagnostic protocol for the ocular evaluation of free-living raptors

Objective: To describe a protocol for the examination of free‐living raptors and report the ophthalmic examination findings of seven raptor species native to central Illinois, namely the barred owl, Cooper’s hawk, eastern screech owl, great horned owl, American kestrel, red‐tailed hawk, and turkey vulture and to determine if the findings relative to visual prognosis affected eligibility for future release. Animals studied: Seventy‐nine free‐living raptors. Procedures: Under manual restraint, complete ophthalmic examination including slit‐lamp biomicroscopy and indirect funduscopy, applanation tonometry, rebound tonometry, ocular morphometrics, B‐mode ultrasound, and electroretinography (ERG) were performed on each bird. Histopathology of enucleated globes was performed after euthanasia or death in selected cases. Results: The examination protocol was easily performed using manual restraint alone on all birds. Ocular lesions were detected in 48.1% of birds, with 47.3% affected unilaterally and 52.6% affected bilaterally. Ocular lesions were considered to be vision threatening in 29.0% of the unilaterally affected birds and 29.0% of the bilaterally affected birds. The most common case outcomes were discharge from hospital to rehabilitation facility (45.6%) followed by euthanasia (43.0%). The presence of an ocular lesion or a vision‐threatening ocular lesion was not significantly associated with outcome. Reference ranges are reported for B‐mode ultrasound, ocular morphometrics, and horizontal corneal diameter in all species. Conclusion: Complete ophthalmic examination can be supplemented by the use of ocular morphometrics, ultrasound, and ERG in the manually restrained raptor. These advanced diagnostic techniques may be useful in developing more objective criteria for evaluating eligibility for release following rehabilitation of free‐living birds of prey.     

The prepurchase examination.

The prepurchase examination is performed to aid a prospective purchaser in determining the suitability of a specific patient for an anticipated use and, perhaps, an intended rider. The ophthalmic portion of that examination can be performed satisfactorily with minimal equipment by following a systematic protocol that includes examination of all segments of the globe and an evaluation of the patient's vision. Findings of the examination should be discussed with and made in writing to the buyer so that he or she can make an informed decision about the suitability of the purchase.     

Diagnostic utility of computed tomography imaging in equine intracranial conditions

Reasons for performing study: The use of computer tomography (CT) and contrast‐enhanced CT (CCT) to image the head is common. However, the validity of CT as a neurodiagnostic indicator of intracranial diseases in horses is unknown. Objective: To define the validity of CT and CCT in horses with suspected intracranial disorders. Methods: The validity of CT imaging was estimated by comparing clinical, clinicopathological and histopathological findings to CT findings in 15 horses presented for intracranial disorders, for which pre‐ and post contrast CT images and post mortem examination of the brain and skull were reviewed. Post mortem examination (gross and histopathological examination) was considered as the gold standard; and sensitivity, specificity, predictive values, likelihood ratios, and pre‐ and post test probabilities were calculated. Results: All horses had abnormal neurological examinations on admission. Computer tomography imaging identified intracranial lesions in 8 horses, and included masses (oligodendroglioma, adenocarcinoma and cholesterinic granulomas), acute haemorrhage and skull fractures. Computer tomography imaging failed to identify intracranial lesions in 6 cases, which included meningitis, meningoencephalitis and nonacute haemorrhage. Lesions not recognised by CT were also not evident on gross examination but were identified by histopathological examination of the brain. Post mortem examination of the brain and skull was unremarkable in one horse, for which cranial CT imaging was normal (specificity, 100%). Therefore, the odds of having an intracranial lesion after an abnormal CT were very high. In contrast, there was a moderate sensitivity (57.1%, 95% confidence interval: 29.6–81.2). Conclusions and potential relevance: CT was an excellent neurodiagnostic tool in identifying skull fractures, intracranial space‐occupying lesions (e.g. neoplasia) and acute haemorrhage and allows to rule in intracranial disorders. However, CT showed limited sensitivity in identifying inflammatory disorders and small parenchymal lesions in the equine brain, which was not further detectable after contrast administration.     

Ophthalmic procedures and surgery in the standing horse.

Although many ophthalmic procedures can be performed on the standing horse, the decision to perform a procedure under sedation rather than general anesthesia must be made on the basis of the temperament of the horse, severity of the injury, and skill of the veterinarian. For example, veterinarians who are not comfortable with small suture material may find accurate repair of an eyelid laceration easier after general anesthesia rather than attempting to handle this suture in a moving patient. Correct use of nerve blocks and topical anesthesia will greatly facilitate examination, diagnosis, and treatment, and, in addition, will serve to prevent further damage to the eye during these procedures.     

Endoscope-guided, transoral axial division of an entrapping epiglottic fold in fifteen standing horses

Objectives— To describe and evaluate the use of a transoral, endoscope-guided technique for transection of an entrapping epiglottic fold in sedated standing horses.
Study Design— Retrospective study.
Animals— Horses (n=16) with epiglottic fold entrapment (EFE).
Methods— Medical records (2005–2006) of 16 horses with EFE were reviewed to determine history, physical and endoscopic examination findings, postoperative complications, and outcome after axial division of EFE using a hooked bistoury, under an endoscopic-guided, transoral approach.
Results— EFE was confirmed by endoscopy. Axial division was successfully performed in 15 sedated, standing horses. One horse had to be anesthetized to complete the procedure. None of the horses made abnormal respiratory noise after surgery and all returned to their intended use. After surgery, 1 horse had a short, deformed epiglottis.
Conclusions— EFE can be axially divided safely and effectively using an endoscope-guided, transoral approach, with the horse sedated and standing.
Clinical Relevance— Endoscopic-guided, transoral axial division of EFE in sedated standing horses is an alternative choice to performing this procedure under general anesthesia.     

Diagnostic validity of palpation in horses with back problems

There is a regularly high proportion of x-ray findings indicating a pathological deterioration of the equine vertebral column which do not correlate with the clinical symptoms. Therefore, palpation remains one of the most important clinical examination methods to determine whether or not a horse is suffering from back pain. The aim of this study was to check the validity of palpation results of horses with an assumed back problem. The palpation results of 167 horses were evaluated in retrospect: If the palpation proceeds under following conditions, positive palpation results agree with an primary back problem in about 100% of cases: 1. Hind limb lameness, being the most likely reason for misleading positive palpation results, has to be ruled out. 2. Only reproducible painful behavior is allowed to be interpreted as positive. Under these conditions a negative palpation result is correct in about 72% of cases. For the examiner it is important to keep in mind that an apparent Kissing Spine-Syndrome can exist without being palpable. By means of clinical examination it is not always possible to distinguish between painful and normal reactions. In doubtful cases diagnosis can be made by a "diagnostic therapy", or better by scintigraphy.