Table 18-2.

Systemic Causes of Conjunctivitis^* in the Dog and Cat

CAUSES	DOG	CAT
Viral diseases	Canine distemper virus Canine herpesvirus in neonates Canine oral papilloma virus Infectious canine hepatitis (canine adenovirus 1 [CAV-1])	Feline rhinotracheitis ([FRV], feline herpesvirus 1 [FHV-1]) Feline calicivirus (FCV) Feline immunodeficiency virus (FIV)
Bacterial and rickettsial diseases	Monocytic ehrlichiosis (Ehrlichia canis) Rocky Mountain spotted fever (Rickettsia rickettsii) Lyme borreliosis (Borrelia burgdorferi)	Chlamydiosis (Chlamydophila felis, formerly Chlamydia psittaci) Neochlamydia hartmannellae (obligate amebic host of Hartmannella vermiformis) Mycoplasmosis (Mycoplasma felis, Mycoplasma gateae, and/or Mycoplasma arginini) has been described as a secondary opportunistic pathogen Bartonellosis (Bartonella henselae, Bartonella spp.)
Protozoal diseases	Leishmaniasis (Leishmania donovani, Leishmania infantum) Trypanosomiasis (Trypanosoma brucei, Trypanosoma vivax)	—
Parasitic diseases	Ophthalmomyiasis (Diptera spp.)	—
Immune-mediated diseases	Canine idiopathic granulomatous disease	—
Dermal diseases	Atopy Zinc responsive dermatosis	Atopy Food hypersensitivity
Miscellaneous diseases	Ionizing radiation Sulfonamides/trimethoprim toxicity in Doberman pinschers	—

^*Associated ocular signs include ocular discharge/secretion, chemosis, congestion, and follicular hyperplasia.