TL;DR: Clear tearing and brown staining (epiphora) is typically a low-urgency cosmetic issue caused by iron oxidation in tears, though you should seek veterinary care if the eye becomes red, painful, or produces thick discharge.
What causes clear tearing and reddish-brown staining on my dog's face?
Clear tearing followed by reddish-brown staining is common in many dog breeds, particularly those with lighter fur. This condition is known as epiphora. The brown color comes from porphyrins, which are iron-containing molecules excreted in tears, saliva, and urine. When these tears sit on the fur, the iron oxidizes upon exposure to air, creating the characteristic rust-colored stain.
Is clear tearing and brown staining a veterinary emergency for my dog?
The urgency level for clear tearing with brown staining is generally Low. While the staining can be unsightly, it is often a chronic condition related to face shape, allergies, or minor tear duct blockages rather than an acute medical crisis. However, you should schedule a veterinary appointment promptly if you notice:
- The eye becoming red or inflamed
- Your dog squinting or holding the eye shut
- The discharge turning thick and yellow or green
How can photos of my dog's eyes help with a veterinary triage?
Taking a clear, well-lit photo of your dog's eyes is an essential part of the triage process. A high-quality image allows a veterinary professional to:
- See the exact location of the staining and the health of the surrounding skin
- Observe whether the eye itself looks clear or inflamed
- Differentiate between common porphyrin staining and serious issues like corneal ulcers or ocular swelling
Clinical Context (Merck Veterinary Manual)
In dogs, clear tearing (epiphora) and brown staining can be caused by obstructions or abnormalities within the tear drainage system, which consists of the lacrimal puncta, canaliculi, lacrimal sac, and nasolacrimal duct. Imperforate lacrimal puncta are an infrequent cause of epiphora in young dogs. Dacryocystorhinography, involving radiographs of the skull after contrast injection into the duct, may be necessary to determine the site and cause of chronic obstructions. Treatment involves maintaining duct patency, sometimes requiring temporary catheterization with polyethylene or silicone tubing, or 2-0 monofilament nylon suture. If the nasolacrimal apparatus is irreversibly damaged, surgical intervention such as conjunctivorhinostomy or conjunctivoralostomy may be required to create a new drainage pathway into the nasal cavity, sinus, or mouth.
Chapter: Ophthalmology
Source: The Merck Veterinary Manual, 11th Edition (Page 491)