Veterinary Articles

Ocular Melanoma
by Noelle La Croix, DVM, Dip. ACVO

The most common primary intraocular tumor of both cats and dogs is melanoma typically presenting within the iris and/or ciliary body. In dog, ocular melanoma presents as a solitary lesion with a low potential for metastasis. In contrast, feline ocular melanoma is typically a diffuse lesion within the iris with a greater propensity for metastasis. [More]

Corneal Transparency
by Noelle La Croix, DVM, Dip. ACVO

A consistent lattice-like arrangement of the stroma's hydrated collagen fibers and the overall volume they occupy (fibril volume fraction) in the cornea is critical for the maintainance of corneal transparency. A proper fibril volume fraction reduces light scattering allowing for corneal clarity. [More]

Glaucomatous Pain
by Noelle La Croix, DVM, Dip. ACVO

Animals with broken limbs typically display obvious signs of discomfort (crying, inappetence, aggressive behavior, etc.). These signs of pain are appreciated by most owners. However, most owners do not see the signs of pain in their pets afflicted with chronically enlarged glaucomatous eyes. Glaucoma is actually painful.

In humans elevated ocular pressures can lead to pain responses typically described as headaches emanating from indiscriminate locations. [More]

The Tear Film - The Outer Lipid Layer
by Noelle La Croix, DVM, Dip. ACVO

This article is the third and final in a series concerning the ocular surface. The outermost lipid layer of the tear film provides a smooth ocular surface for proper light refraction and helps prevent the evaporation of the tear film. [More]

The Tear Film - The Glycocalyx and Mucin
by Noelle La Croix, DVM, Dip. ACVO

This article is the second in a series concerning the ocular surface. The tear film plays a critical role in the health of eye and a number of ocular disorders can affect the tear film. The tear film break-up time (TFBUT) test is used to analyze the stability of the tear film and its evaporative rate. [More]

The Ocular Surface - The Tear Film
by Noelle La Croix, DVM, Dip. ACVO

The tear film covers the entire ocular surface. The tear film's volume is distributed across the eye so that approximately 1 μl lies across the exposed surface, 2.9 μl is found at the margins, and some additional volume is found beneath the eyelid. The tear volume is spread thinly across a much larger surface area which allows capillary forces to outweigh gravitational forces. Therefore, the tear film normally stays "attached" to the ocular surface. [More]

Ocular Steroidal Medications
by Noelle La Croix, DVM, Dip. ACVO

There are many different formulations of ocular steroidal medications. This article will highlight some of the important aspects of the relationship between steroidal medications and the eye. The appropriate choice and usage of ocular steroids is affected by their pharmacodynamics. [More]

Diseases of the Orbit
by Noelle La Croix, DVM, Dip. ACVO

Exophthalmos (bulging of the eye from the orbit) is often insufficient criteria for a diagnosis of orbital disease. It can be difficult to define the "abnormal" displacement of a veterinary patient's eye. An eye may appear exophthalmic, but is in actuality "normal" in position compared with a contralateral enophthalmic or phthisical eye. Buphthalmos (enlargement of the eye), unilateral pupillary dilation, facial nerve paralysis, and ptosis can also be mistaken for exophthalmos. A systematic ophthalmic examination is therefore necessary to detect and identify true orbital disease. [More]

Ocular and Dermatologic Disease
by Noelle La Croix, DVM, Dip. ACVO and Judy Seltzer, DVM, Dip. ACVD

The lacrimal glands, conjunctiva, meibomian glands, cornea, and eyelid skin are all derived from the surface ectoderm of an embryo.  The body's skin is also derived from this embryonic ectoderm.  Meibomian glands are greatly enlarged and modified sebaceous glands that lack hair follicles.  Their development is quite similar to skin hair follicles.  In addition to these analogous origins, ocular and dermatological health are often correlated.  These relationships will be discussed in this article. [More]

The Ophthalmic Examination - Part 2:
The adnexa, orbit, and anterior segment

by Noelle La Croix, DVM, Dip. ACVO

The previous article in this series discussed menace responses, pupillary light and dazzle reflexes in the ophthalmic examination of companion animals. The examination continues by evaluating the anterior segment of the eye in a standardized manner. [More]

The Ophthalmic Examination - Part 1:
Menace response, pupillary light and dazzle reflexes

by Noelle La Croix, DVM, Dip. ACVO

Veterinary ophthalmic examinations are performed in a defined anatomical order while evaluating visual responses and reflexes with the objective of establishing a primary diagnosis. [More]

Keratoconjunctivitis Sicca - Part 2:  Clinical signs and treatment of KCS
by Noelle La Croix, DVM, Dip. ACVO

Ocular discharge is often the first clinical sign of KCS appreciated by companion animal owners. This sticky mucopurulent discharge is secondary to the collapse and blending of the mucous and lipid layers of the tear film. [More]

Keratoconjunctivitis Sicca - Part 1:  Structure of the Tear Film
by Noelle La Croix, DVM, Dip. ACVO

The precorneal tear film is essential for the health and function of the ocular surface.  As the first refractive surface of the eye, the tear film's health is also necessary for visual clarity...The innermost layer is a glycocalyx extending outward form corneal and conjunctival epithelia. [More]

The Melanoma Vaccine
by Edwin Brodsky, DVM, Diplomate ACVIM (Oncology)

Oral melanoma is the most common malignant oral tumor in dogs. Oral melanomas are both locally aggressive and systemically aggressive (up to 80% metastatic rate). [More]

Targeted Therapy
by Edwin Brodsky, DVM, Diplomate ACVIM (Oncology)

Recently, a great deal of research has been done in both normal and cancerous cells regarding the signals involved in cell growth, differentiation and survival.  Normal cells receive signals from outside the cell via molecules called growth factors. [More]

Metronomic Chemotherapy
by Edwin Brodsky, DVM, Diplomate ACVIM (Oncology)

In order for cancer to grow beyond 2mm in diameter, a tumor needs to recruit its own blood supply. This process is called angiogensis. [More]

Mast Cell Tumor Proliferation
by Edwin Brodsky, DVM, Diplomate ACVIM (Oncology)

Mast cell tumors are the most common cutaneous malignancy in dogs. One of the most important prognostic factors when treating mast cell tumors is the histologic grade. The histologic grade is a measure of how aggressive a tumor appears on a biopsy. [More]

Chemotherapy in Veterinary Medicine
by Edwin Brodsky, DVM, Diplomate ACVIM (Oncology)

When people think of chemotherapy they generally assume horrible side effects such as severe vomiting, diarrhea, weight loss, lethargy and an overall poor quality of life.  However, in veterinary medicine, the majority of patients (80-85%) have minimal to no side effects when receiving chemotherapy. [More]

Uveitis - Treatment
by Noelle La Croix, DVM, Dip. ACVO

In two previous articles, I discussed the nature of uveitis and its diagnosis.  In this final article of this series, I want to discuss the treatment of uveitis. Treatments involve appropriate medications, follow-up evaluations of medicinal efficacy, and ultimately the tapering of medications as clinical signs resolve. [More]

Antibiotics to Treat Corneal Infections
by Noelle La Croix, DVM, Dip. ACVO

Antibiotics can effectively treat corneal infections and prevent further complications (e.g.; corneal rupture, loss of vision). Simplistically, the appropriate topical antibiotic is chosen based upon specific bacterial susceptibility. Melting corneal ulcers with unabated infections may rupture within 24 hours of presentation. However, the identification and antibiotic sensitivities of infective bacteria are typically obtained 2 to 3 days after initial culture. Antibiotics are therefore initially chosen to combat the most common bacteria found in corneal infections. [More]

The Art of Aseptic Technique in Ophthalmic Surgery
by Noelle La Croix, DVM, Dip. ACVO

Postoperative endophthalmitis and corneal infection are rare but serious complications of intraocular surgery. Postsurgical infection of periocular tissues (eyelids, conjunctiva, and/or third eyelid) can result in significant visual impairment. [More]

Uveitis - Diagnosis
by Noelle La Croix, DVM, Dip. ACVO

A large spectrum of ocular disorders are associated with uveitis.  The particularly etiology can sometimes be determined from a patient's history and physical examination prior to diagnostic testing.  Historical background might include environmental factors, adverse reactions to medications, autoimmune disorders, etc.  Physical examination will determine if the uveitis is uni- or bilateral; non- or granulomatous, and define its location (anterior, posterior, or pan-).  A complete physical examination can also reveal additional signs of underlying inflammatory disease such as swollen lymph nodes, an abdominal mass, or petechiae. [More]

by Noelle La Croix, DVM, Dip. ACVO

The complicated anatomy of the eye can be roughly divided into 3 layers: an outer fibrous layer (cornea and sclera), a middle vascular layer (choroid and iris), and an inner neurological layer (retina). Uveitis is defined as inflammation within the middle layer commonly called the uvea (Latin grape). The name probably derives from early anatomists that would remove this small bluish-purple (grape-like) tissue from the human eye. Unfortunately, inflammation of the uvea can lead to a wide spectrum of disease. Uveitis can be acute and self-limiting or act as a progressive syndrome (panuveitis) which can lead to blindness. [More]

Twenty-five Ophthalmic Insights
by Noelle La Croix, DVM, Dip. ACVO

Recently, a colleague asked me to list some of the basic insights into the practice of veterinary ophthalmology that I have learned over the years.  The following is a non-comprehensive list (in no particular order) of some of that knowledge that I hope will aid in your treatment of ophthalmic cases. [More]

The Neurology of Lacrimation – How an Ear Infection Can Cause Dry Eye
by Noelle La Croix, DVM, Dip. ACVO

Neurogenic keratoconjunctivitis sicca (KCS or dry eye) can be a frustrating disease to treat.  There are successful drugs to combat dry eye (tacrolimus and cyclosporine) but they sometimes fail in cases with a neurological basis.  In this article I will review the neurology of lacrimation and the pathology of neurogenic KCS. [More]

Traumatic Proptosis
by Noelle La Croix, DVM, Dip. ACVO

A traumatic proptosis is an ophthalmic emergency which can ignite both panic and revulsion in a client.  However, a systematic and sympathetic approach from a veterinarian can often calm the client and encourage a positive outcome. [More]

Ocular and Oral Disease
by Noelle La Croix, DVM, Dip. ACVO

The complex anatomy of the eye and orbit is intimately juxtaposed with that of the oral cavity. Oral disease can adversely impact ocular health in several ways.  Foreign bodies and/or infectious organisms can directly traverse the oral cavity and enter the orbit. [More

Antibiotics to Treat Corneal Ulceration
by Noelle La Croix, DVM, Dip. ACVO

There are a number of antibiotics that are available to treat corneal ulceration. The appropriate antibiotic will specifically kill the opportunistic or contaminating bacteria within the corneal ulcer. [More]

Pemphigus Foliaceus
by Judy Seltzer, BVetMed, MRCVS, DACVD

Pemphigus foliaceus is an autoimmune disease where antibodies produced by an animal’s own immune system attack the bridges that hold skin cells together. The deposition of antibody in intercellular spaces causes the cells to detach from each other within the uppermost epidermal layers- this is known as acanthosis. [More]

Malassezia (Yeast) Dermatitis
by Judy Seltzer, BVetMed, MRCVS, DACVD

Malassezia dermatitis and otitis occurs most commonly in animals with allergies, endocrinopathies (hypothyroidism, Cushing’s disease), immunosuppressive diseases and other skin diseases. The most common causative organism is Malassezia pachydermatis. [More]

by Noelle La Croix, DVM, Dip. ACVO

Fluorescein is a fluorescent dye first synthesized by the Nobel prize-winning chemist Albert Baeyer in 1871. It is derived from aromatic compounds (benzene and its derivatives) and contains four aromatic rings of carbon. [More]

What Is Bloat? (Gastric Dilatation and Volvulus (GDV))
by Jennifer Lang, DVM

"Bloat" is a term commonly used to describe gastric dilatation and volvulus (GDV).

When GDV occurs, a dog’s stomach becomes distended and twists on itself. As the stomach twists it cuts off escape routes (through the esophagus and small intestines) for gas, fluid, and food. Dogs are unable to vomit or belch to relieve the pressure in the stomach. As the stomach becomes progressively more distended, damage to the stomach, shock, and death can occur. [More]

The Schirmer Tear Test
by Noelle La Croix, DVM, Dip. ACVO

An examination of an animal’s eye should include a thorough history, visualization of both anterior and posterior ocular structures (via ophthalmoscopy), tonometry, fluorescein staining, and the Schirmer tear test.  This article will review the purpose and relevance of the Schirmer tear test. [More]

Some Basic Principles of Tonometry
by Noelle La Croix, DVM, Dip. ACVO

The diagnostic measurement of intraocular pressure (IOP) is important in accessing ocular disease.  Most practices today use an applanation tonometer (Tono-Pen Vet™ - Reichert, Inc.) that infers IOP by flattening a small section of the cornea.  This article will describe some of the basic principles that underlie this instrument's use. [More]

Canine (not human) Glaucoma
by Noelle La Croix, DVM, Dip. ACVO

It can be very difficult for clients to understand their dog’s loss of vision when caused by glaucoma. Clients tend to associate ‘glaucoma’ with the disease of their affected parents or grandparents. Glaucomatous humans typically receive medications and regular ocular pressure checks, but do not usually develop complete blindness. However, canine glaucoma is quite different than human glaucoma. [More]

Canine Eye Registration Foundation (CERF) Exams
by Noelle La Croix, DVM, Dip. ACVO

Centuries of selective matings for various phenotypic traits has generated the diverse assortment of dog breeds seen today. However, this in-breeding has also greatly diminished the genetic diversity within each specific breed. In populations of low genetic diversity, recessive alleles are more likely to pair. Paired non-lethal recessives often generate phenotypes with decreased biological fitness. [More]

The Canine Optic Nerve
by Noelle La Croix, DVM, Dip. ACVO

The optic nerve is commonly referred to as a cranial nerve. However, it is actually an outpocketing of the diencephalon. Both the brain and the optic nerve are encased within the meninges. The optic nerve acts as a pathway by which ganglion cell axons transverse from the retina to the brain (lateral geniculate nucleus, superior colliculus, hypothalamus, pretectum, etc). [More]

Ocular Medications
by Noelle La Croix, DVM, Dip. ACVO

There are 3 major components in all eye drop medications: drug(s), solution (vector), and preservative(s).  Eye ointments generally contain fewer preservatives than eye drops as their liquid-free (oil based) vectors greatly inhibit bacterial growth.  Eye drops solutions have generally been designed to match the osmolarity and pH of the ocular surface, and to stabilize the drugs to be administered.  From a veterinary standpoint, preservatives can be responsible for adverse reactions to ocular medications. [More]

"Does my dog see in black and white?"
Answers to Questions about Companion Animal Vision – Part 1
by Noelle La Croix, DVM, Dip. ACVO

The mammalian eye is a device for collecting and focusing light, for distinguishing between different wavelengths and intensities, and for converting that information into electrical impulses that are sent to the brain.  Eyes evolved independently in various ecological niches creating species-specific morphologies.  In general, an eye conferred a selective survival advantage to an individual, and therefore a reproductive advantage in a population. [More]

"Can my dog watch TV?"
Answers to Questions about Companion Animal Vision – Part 2
by Noelle La Croix, DVM, Dip. ACVO

In part 1 of this article, we reviewed color vision, light sensitivity and visual acuity in the dog.  This article will review canine depth perception, field of view, and motion detection.  I will also describe "flicker fusion" and how it relates to dogs watching television. [More]

by Noelle La Croix, DVM, Dip. ACVO

Enucleation refers to the surgical removal of the entire eye.  This procedure is indicated for relatively few conditions that you and your client may face.  One cannot underestimate the attachment of an owner to the eye of their pet.  However, when necessary, enucleation can relieve suffering and prevent future maladies. [More]

Eyelid Reconstruction
by Noelle La Croix, DVM, Dip. ACVO

Eyelids protect the cornea from trauma, refresh the tear film, sweep away foreign debris, and block light during sleep. In mammals, the upper eyelid rises above the pupil allowing for vision and it reflexively closes (or blinks) to protect and lubricate the cornea. Trauma, neoplasia, and genetic disorders may necessitate the reconstruction of an animal eyelid. [More]

Antiglaucoma Medications
by Noelle La Croix, DVM, Dip. ACVO

Glaucoma is a disease of the optic nerve in which retinal ganglion cells atrophy, often resulting in blindness (Figure 1).  Elevated intraocular pressure (IOP) is a major risk factor for the development of glaucoma.  The key to glaucoma management is to determine its underlying cause.  Different etiologies require different treatments.  A veterinary ophthalmologist will explore both surgical and pharmaceutical options to reduce IOP.  This article will summarize the most common antiglaucoma medications used by a veterinary ophthalmologist to preserve vision in dogs. [More]

Why Cats Are Not Little Dogs – Some Thoughts on Feline Ophthalmology
by Noelle La Croix, DVM, Dip. ACVO

Veterinarians face unique challenges when a cat with an “eye problem” arrives at their practice.  The presentation, diagnosis, treatment, and underlying pathology of feline ophthalmic disorders often differ from their canine counterparts.  This brief review will contrast feline and canine ophthalmology, and describe some novel features of feline ocular anatomy. [More]

Blood in the Eye.  Part 1.  Primary Intraocular Conditions
by Noelle La Croix, DVM, Dip. ACVO

Hemorrhage or bleeding into the anterior chamber of the eye is classified as hyphema.  The pathogenesis of hyphema is diverse, but a breakdown of the blood ocular barrier (BOB) and subsequent inflammation (uveitis) is usually involved.  Except in cases of severe intraocular disease, the differential diagnosis of hyphema does not differ from hemorrhage in other parts of the body (e.g.; hemoabdomen, pericardial hemorrhage). [More]

Blood in the Eye.  Part 2.  Secondary Systemic Conditions
by Noelle La Croix, DVM, Dip. ACVO

Hyphema is hemorrhage, or bleeding, into the anterior chamber of the eye.  In the last newsletter, I discussed the main primary intraocular conditions (trauma, uveitis, cancer, and retinal detachment) which cause hyphema.  This article will discuss hyphema that arises secondary to systemic disease. [More]

by Noelle La Croix, DVM, Dip. ACVO

To the casual observer a pupil appears black, even though there is a direct transparent pathway from a pupil to a colorful retina.  Ambient light enters an eye through its pupil at a multitude of different angles. [More]

A Review of Canine and Feline Oral Tumors
by Dan Carmichael DVM, Diplomate AVDC

The oral cavity is a common site of malignant neoplasia in both the dog and the cat. Tumors of the oral cavity can be classified as odontogenic tumors (neoplasia arising from tooth-forming tissues), non-odontogenic tumors, or non-neoplastic lesions. [More]

Ocular Herpes in Kittens
by Noelle La Croix, DVM, Dip. ACVO

The feline herpesvirus (FHV-1) was first isolated in 1958. The virus can replicate within the conjunctival epithelia, upper respiratory tract epithelia, and sensory ganglia. Neuronal infection with FHV-1 establishes lifelong latency with intermittent re-activation and viral shedding. Virus transmission is commonly associated with exposure to acutely infected cats, or recrudescing latently infected cats. Environmental contamination with FHV-1 is not considered a significant route of transmission. [More]

Genetic Testing in Veterinary Ophthalmology
by Noelle La Croix, DVM, Dip. ACVO

As discussed in an earlier article, the selective breeding of the canine has greatly diminished the genetic diversity within each specific breed. In populations of low genetic diversity, recessive alleles are more likely to pair. Paired non-lethal recessives often generate phenotypes with decreased biological fitness. [More]

Cranial Curuciate Ligament Instability: Introducing the Tibial Tuberosity Advancement
by Dr. Margret Puccio, DVM, Diplomate ACVS

Cranial cruciate ligament injuries are one of the most common causes of acute and chronic lameness in dogs and are also seen as a cause of lameness in cats. Unstabilized cranial cruciate ligament tears place the patient at risk of meniscal damage and osteoarthritis of the stifle joint. [More]

Interventional Radiology Techniques
by Dr. John Fondacaro, Diplomate ACVIM & Dr. Sean Hillock, Diplomate ACVIM

Since there is not an abundance of information about these procedures in the literature, the following general information will help you decide which patients may be possible candidates and allow you to adequately prepare owners prior to referral. [More]

Canine Bacterial Keratitis - When Ulcers Go Bad
by Dr. Noelle La Croix, DVM, Dip. ACVO

The cornea is a transparent tissue lacking pigments, blood vasculature, and keratinized epithelia. These properties are essential for vision, but also make the cornea susceptible to infection. The tear film acts as a physical barrier to microrganisms, prevents microbial growth with lysozyme and lactoferrin, and provides nutrition to the corneal epithelium. [More]

Cataract Referral
by Dr. Noelle La Croix, DVM, Dip. ACVO

A cataract is any opacification of the lens. Crystallins within lens fibers, or the lens fibers themselves, are disorganized within a cataract. Ultimately, crystallin disorder decreases transparency or light transmittance. Cortical cataracts are histologically associated with disordered, swollen, and ruptured lens fibers. [More]

Feline Dental Problems
by Dr. Daniel T. Carmichael

Dental disease is common in domestic felines. In fact, dental problems are the most common disease that we see in cats, and many dental problems are painful. The most common sign of pain in cats, however, is no sign at all. By diagnosing and rendering appropriate treatment, we can eliminate pain and afford our feline patients a better quality of life. [More]

Taking Care of your Pet's Teeth at Home
by Dr. Daniel T. Carmichael

The consequences of poor dental health go way beyond bad breath.  Periodontal infection can lead to serious health concerns ranging from tooth loss to organ failure.  It’s also no secret that dental problems are common in animals – studies have shown dental problems to be the most common problem in both dogs and cats, with periodontal disease at or near the top of the list. [More]

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