Infectious bovine keratoconjunctivitis (IBK), commonly known as pinkeye, has been around the beef industry for more than 120 years, with USDA estimating economic losses at more than $150 million a year. Severe cases can result in low weaning weights, blindness or eye loss. It is not uncommon for calves affected with pinkeye to bring $10/hundredweight less than herdmates at auction.
IBK is identified by redness in the outer edges of the eye, squinting, tearing and clouding of the cornea. Bacteria most likely enter, even progressing to complete deterioration of the eye via acornea and prolapse of Decemet's membrane. Pinkeye-associated bacteria are opportunistic members of the normal ocular flora and likely cause disease following trauma contributed to the cornea by flies, dust, ultraviolet (UV) light, projectiles on hay feeders and long grasses in pastures.
Pinkeye-associated bacteria likely cause disease following trauma contributed to the cornea by flies, dust, ultraviolet (UV) light, projectiles on hay feeders and long grasses in pastures.
The primary etiologic agent of IBK has historically been recognized as Moraxella bovis. But another agent, Moraxella branhamella ovis, has been isolated, and these bacteria are found to possess many of the virulence factors found in virulent Moraxella bovis strains.
M. branhamella ovis isolate often
Spencer Veterinary Clinic, Spencer, Neb., began culturing eyes two years ago when 25 percent to 50 percent of cattle vaccinated in several herds with commercial products were affected with pinkeye lesions. Cultures taken from three animals per herd have isolated two primary agents: Moraxella bovis and/or Moraxella subspecies branhamella ovis.
In 2000, in 14 out of 24 cases, the bacteria was Moraxella branhamella ovis. In 2001, 50 eyes were cultured, with Moraxella branhamella ovis isolated in 36 cases. So far in 2002, 32 cultures have been taken. Moraxella branhamella ovis is the bacteria isolated in 20 cases, with Moraxella bovis isolated in just four cases. It must be noted, however, that both bacteria were isolated in several cases, and neither bacteria was identified in eight cases.
The results are similar to those found by researchers at the Nebraska Veterinary Diagnostic Center. Susanne Hinkley, DVM, PhD, and Henry E. Cerny, DVM, MS, studied the frequency of isolation of Moraxella bovis and Moraxella branhamella ovis from more than 180 isolates of clinical IBK cases and found 75 percent were Moraxella branhamella ovis and 25 percent were Moraxella bovis.
About two-thirds of Spencer Veterinary Clinic clients who have had pinkeye lesions cultured have requested that a custom autogenous vaccine be manufactured for their particular ranch, since commercial vaccines cover only Moraxella bovis. Cultures can be easily obtained when cattle are being treated for pinkeye. For successful results, it is important to obtain a culture before in the later early stages of the disease and to have an experienced, qualified laboratory create the custom vaccine autogenous bacterin.
Since a custom autogenous vaccine is developed for a particular strain of bacteria causing the pinkeye, protection is being provided against that strain. Over the past three years, occurrence of pinkeye in most of the clinic's herds using a custom autogenous vaccine has dropped to zero, and only very few cases of pinkeye have occurred in the other herds.