NEW CAUSE OF GLAU­COMA IN HORSES

EQUUS - - Eq Medical Front -

the de­vel­op­ment of EMPF. The host im­mune re­sponse, how­ever, is defini­tively in­volved in this process.”

The cur­rent “gold stan­dard” for di­ag­nos­ing EMPF is a lung biopsy to look for signs of fi­bro­sis, com­bined with a pos­i­tive poly­merase chain re­ac­tion (PCR) test for EHV-5 within the tis­sue sam­ples. Lung biop­sies, how­ever, can be dif­fi­cult to ob­tain from a horse show­ing se­vere res­pi­ra­tory signs and may lead to se­ri­ous com­pli­ca­tions.

Look­ing for an eas­ier al­ter­na­tive, the Davis re­searchers sought to de­ter­mine how ef­fec­tive the test­ing of blood, nasal se­cre­tions and lung fluid could be in iden­ti­fy­ing EHV-5-associated EMPF.

The re­searchers first used clin­i­cal find­ings, ra­dio­graphic imag­ing and analysis of lung tis­sues and fluid to di­vide 70 horses into four groups: those with no res­pi­ra­tory ill­nesses, those with in­flam­ma­tory air­way disease, those with non-EMPF in­ter­sti­tial lung diseases and those with EMPF. PCR was then used to test each horse’s blood, nasal se­cre­tions and lung fluid for EHV-5.

The data showed that the pres­ence of EHV-5 in lung fluid was strongly associated with EMPF. “Although pos­si­ble, it is very rare to find a horse that tests pos­i­tive for EHV-5 in lung fluid that does not have EMPF,” says Pusterla.

EHV-5-pos­i­tive blood and nasal se­cre­tion tests were also associated with EMPF, but with lower sen­si­tiv­ity (mean­ing the tests could miss some cases) and speci­ficity (mean­ing the tests could pro­duce false pos­i­tives). Con­sid­ered to­gether, how­ever, pos­i­tive blood and nasal se­cre­tion tests were more re­li­able in de­tect­ing horses with EMPF than each was on its own.

These find­ings, says Pusterla, show that less in­va­sive mea­sures can be used in­stead of lung biop­sies in mak­ing a di­ag­no­sis of EMPF. “In a case sus­pected on the ba­sis of clin­i­cal and ra­dio­graphic ab­nor­mal­i­ties, blood and nasal se­cre­tions pos­i­tive for EHV-5 can sup­port that di­ag­no­sis,” he says. Con­fir­ma­tion of the di­ag­no­sis can be made via PCR test­ing of lung fluid or a lung biopsy.

Ref­er­ence: “As­sess­ment of quan­ti­ta­tive poly­merase chain re­ac­tion for equine her­pesvirus-5 in blood, nasal se­cre­tions and bron­choalve­o­lar lavage fluid for the lab­o­ra­tory di­ag­no­sis of equine multin­odu­lar pul­monary fi­bro­sis,” Equine Vet­eri­nary Jour­nal, pub­lished on­line Jan­uary 2016

A new cause for glau­coma in horses is doc­u­mented in a re­cently pub­lished re­search pa­per.

The pa­per de­scribes the cases of five horses re­ferred to vet­eri­nary clin­ics in var­i­ous parts of the coun­try---Min­nesota, New York, Ohio and Washington State---be­cause of se­vere fluid buildup in the cornea (corneal edema), high pres­sure within the eye­ball (glau­coma) and corneal

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