Image Gallery: Canine Fundus Diseases

FIGURE 1 Normal canine retina

Normal canine retina in a 3-year-old spayed Chihuahua. Practitioners should be comfortable identifying the optic nerve (red arrow), tapetal fundus (blue arrow), nontapetal fundus (white arrow), and retinal vasculature (black arrow).  

FIGURE 2 Intraretinal hemorrhage

Multifocal retinal petechiae (white arrows) were identified during routine eye examination of a 13-year-old spayed poodle mix. The patient was not exhibiting visual deficiency but did have a Doppler blood pressure reading of 220 mm Hg. After 3 months of antihypertensive therapy, all intraretinal petechiae had resolved. Systemic hypertension in dogs can be primary, or secondary to renal disease, hypothyroidism, diabetes mellitus, hyperthyroidism, primary aldosteronism, or a pheochromocytoma.¹

FIGURE 3 Bullous retinal detachment

A 12-year-old spayed Akita was presented with bullous retinal detachment (white arrows), resulting from systemic hypertension (blood pressure, 225 mm Hg). A flash artifact is seen in the superior aspect of the image (red arrow). Depending on duration of the retinal detachment and whether systemic hypertension can be controlled, patients with similar retinal detachments can regain vision²; however, this dog did not regain vision.

FIGURE 4 Multiple bullous retinal detachments

In this 8-year-old castrated golden retriever, multiple bullous retinal detachments (black arrows) are attributed to secondary hypertension (blood pressure, 230 mm Hg) as caused by hyperadrenocorticism. In addition, retinal vasculature tortuosity (white arrow) is evident throughout the detached retina. A flash artifact is visible in the inferior aspect of the image (red arrow). Depending on duration of the retinal detachment and whether systemic hypertension can be controlled, patients with similar retinal detachments can regain vision.² Despite eventual control of its high blood pressure, this dog never regained vision in its affected eye. 

FIGURE 5 Collie eye anomaly

In this 2-year-old castrated collie, choroidal hypoplasia is present (yellow arrow) at the tapetal and nontapetal fundus. In this particular area, the retinal pigmented epithelium as well as the tapetum lucidum are lacking; thus the choroidal vasculature can be seen. In addition, the patient has an optic disk coloboma (blue arrow), which can occur in dogs with collie eye anomaly.³ Optic nerve colobomas typically appear as holes or excavations in the optic disk. Of note, no vision difficulties were apparent in this patient. A flash artifact can be seen at the superior aspect of the image (red arrow). There is a purple reflection that is an artifact at the inferior aspect of the image (white arrow). 

FIGURE 6 Chronic glaucoma

In this 10-year-old castrated Australian cattle dog, chronic primary glaucoma is indicated by increased intraocular pressures of >45 mm Hg (normal range: <25 mm Hg) for more than 6 weeks. Common retinal examination findings in dogs with chronic glaucoma include a cupped, or depressed, optic nerve head (white arrow) and diffuse vascular attenuation (black arrow). In this dog, prognosis for return to vision was grave. Note the flash artifact visible at the superior aspect of the image (red arrow).

FIGURE 7 Optic nerve hypoplasia

As evident in this 6-year-old neutered German shepherd dog with optic nerve hypoplasia, the optic nerve head is darker and smaller than normal (red arrow). In dogs, optic nerve hypoplasia is considered a congenital optic neuropathy.⁴ The genetic basis for this condition is thought to be undefined, recessive, or dominant.⁴ Of note, the direct pupillary light reflex was absent, but the consensual pupillary light reflex was normal. No visual deficits were apparent, which is common in dogs with optic nerve hypoplasia. Optic nerve micropapilla would also be a differential diagnosis; these patients have normal vision and pupillary light reflexes. A reflection artifact is located at the inferior aspect of the image (white arrow). 

FIGURE 8 Optic neuritis

Inflammation of the optic nerve as shown is consistent with optic neuritis. This 3-year-old spayed Jack Russell terrier was presented was presented with acute blindness and bilateral mydriasis; loss of the physiologic cup (white arrow) and peripapillary edema (red arrow) are evident. The key distinguishing feature of the loss of a physiologic cup is a more “flattened” appearance to the face of the optic nerve. The blood vessels that cross the edges of the optic nerve do not dive down into the center of the nerve but rather appear more flattened. Common causes of optic neuritis are the same as the causes of central nervous system inflammation. Infectious causes include systemic fungal infections (eg, cryptococcosis, histoplasmosis, blastomycosis), orbital abscesses, canine distemper virus, and ehrlichiosis. Noninfectious causes include trauma, orbital neoplasia, optic nerve neoplasia, brain tumors, and vitamin A deficiency. In dogs with optic neuritis, prognosis for return to vision is poor.⁴ In this dog, the cause of optic neuritis was not determined. 

FIGURE 9 Retinal degeneration

This 9-year-old spayed poodle has multiple retinal abnormalities, including optic nerve pallor (red arrow), diffuse tapetal hyperreflectivity (black arrow), and severe vascular attenuation (white arrow), all of which are consistent with progressive retinal atrophy. The patient was experiencing vision loss in dim light conditions. The contralateral retina was similar in appearance. Retinal degeneration can be secondary to inheritance, nutritional causes, or age.⁵

FIGURE 10 Retinal detachment with dialysis

This 8-year-old castrated shih tzu has a complete retinal detachment (white arrow) with dialysis. Retinal dialysis is where the retina tears at the ora serrata but remains attached around the optic nerve. The cause of retinal detachment was suspected to be vitreoretinal detachment. Other potential causes include systemic hypertension, subretinal infiltrate, tick-borne disease, and neoplasia.⁵ The retina is torn at the ora ciliaris retinae (peripheral retina) and hangs ventrally into the vitreous at the optic nerve head (black arrow). Diffuse tapetal hyperreflectivity is also apparent. This condition is managed surgically rather than medically. However, even with surgical intervention, prognosis for return to vision is grave. A flash artifact is noted in the superior aspect of the image (red arrow). 

FIGURE 11 Normal subalbinotic retina

Subalbinotic retina (ie, variation in color) is evident in this 10-year-old castrated boxer; note that a finding of diffuse choroidal vasculature is normal. In animals with subalbinotic retina, the choroidal vasculature is seen throughout the fundus, with no presence of a tapetal or nontapetal fundus. A flash artifact is apparent (white arrow). Subalbinotic retinas also commonly appear in Siberian huskies, merle Australian shepherds and merle border collies.