Is a runny nose in a desert tortoise always a respiratory infection or could it be something else? question from Karen Keller, Carson, California
A clear nasal discharge that is watery in nature (serous rhinitis) may be caused by numerous factors, but is abnormal unless associated with recent water drinking. Reptiles lack a complete hard palate so there is a direct communication between the oral and nasal cavities (choanae) that can allow a reflux of water back out the nostrils. I have seen rhinitis associated with the stress of heavy intestinal parasite loads, which cleared up upon treatment with a deworming agent. This can be diagnosed at a veterinary facility by microscopic examination of a fecal smear and floatation of a stool sample. Bladder stones (urinary calculi or uroliths) can cause internal trauma to the lungs and result in nasal drainage. Excess salivation and inhaled irritants such as pollen or foreign bodies can also lead to rhinitis.
Environmental conditions that are suboptimal, such as too damp or cold, can predispose chelonians to severe contagious upper respiratory infection, which may progress to lower respiratory tract disease (pneumonia) with grave consequences. Likewise, stress from over-crowding or malnutrition can predispose to upper respiratory infections, so quality of the diet should be considered as well as over-all husbandry. For example, vitamin A deficiency (hypovitaminosis A) causes thickening of the lining tissues of the eyelids and nose and may lead to secondary bacterial infections. When a bacterial infection affects the nasal sinuses (sinusitis), the discharge tends to be copious, opaque and thick (mucopurulent rhinitis) and may be one-sided (unilateral).
Prescribed antibiotics should be used to treat the rhinitis at this stage, preferably based on bacterial culture and sensitivity test results. In chelonians of many species, but especially in the desert tortoise, the primary infectious bacterial agent is Mycoplasma agassizii with common secondary gram-negative bacterial agents such as Pasteurella species complicating the condition. There is a blood test for the Mycoplasma available at the University of Florida, Gainesville that should be performed if infection is suspected as the cause of the rhinitis.
Dennis L. Fees, DVM
Arcadia Small Animal Hospital, Arcadia, CA
Originally published in the Tortuga Gazette 34(10): 9, October 1998