Primary angle-closure glaucoma in dogs: latanoprost vs other first-line drops (or vehicle) — POSSIBLE

In dogs with primary angle-closure glaucoma, does latanoprost vs other first-line drops (or vehicle) lower intraocular pressure more?

Shelf #328 · gate-verified and approved by the developer

POSSIBLE: Latanoprost lowers intraocular pressure (IOP) substantially against vehicle — but the randomised evidence is not in angle-closure patients. Anchor correction, stated on the face of the cards: Gelatt & MacKay 2001, the draft anchor, studied eight laboratory Beagles with inherited primary OPEN-angle glaucoma, not client-owned dogs with primary angle-closure glaucoma. In that model, 0.005% latanoprost in one eye vs 0.5% methylcellulose placebo in the fellow eye produced mean diurnal IOP declines of about 23–26 mmHg over four days of once-daily dosing (and about 19–20 mmHg twice daily), significantly different from the control eye; travoprost in the same model (Gelatt & MacKay 2004) behaved similarly (about 19–28 mmHg). In the actual angle-closure population, the only carded record is retrospective (Dees 2014, 88 client-owned dogs, prophylaxis of the at-risk fellow eye): latanoprost's estimated median time to medical failure was 284.0 days, between demecarium bromide 0.125% (330.0 days) and dorzolamide 2.0% (272.5 days), and no medication statistically delayed failure compared with the others. So: a real, large IOP-lowering effect vs vehicle in the laboratory model; superiority over other first-line drops in primary angle-closure glaucoma itself is unproven, which is why this shelf is POSSIBLE and not higher. Drafted Nov 10, 2026 (VetMed build, topic #328); all figures from abstracts fetched and verified at drafting.

Gelatt & MacKay 2001: latanoprost lowered IOP by roughly 20–26 mmHg diurnally vs methylcellulose placebo in glaucomatous Beagles

Randomized Controlled Trial (record's publication type); fellow-eye placebo control, eye allocation by random table

Who: Dogs: eight laboratory Beagles with the moderate stage of inherited primary open-angle glaucoma (a laboratory colony model — NOT client-owned dogs with primary angle-closure glaucoma); 0.005% latanoprost was instilled in one eye and 0.5% methylcellulose (as placebo) in the fellow control eye, with control and drug eyes selected using a random table, in three 5-day multiple-dose studies (once in the morning, once in the evening, or twice daily).

Result: On the first day, mean ± SEM diurnal declines in IOP were 8.4 ± 4.0 mmHg in latanoprost eyes vs 6.5 ± 3.6 mmHg in placebo eyes (8 am study). Over the next four days of once-daily 8 am latanoprost, mean diurnal IOP declines in drug eyes were 23.3 ± 5.0, 25.4 ± 2.1, 25.7 ± 1.7 and 26.1 ± 1.7 mmHg, significantly different from the control eye; with 8 pm instillation the declines were 24.9 ± 2.1, 22.4 ± 1.8, 21.6 ± 1.9 and 26.6 ± 2.2 mmHg, and with twice-daily instillation 19.6 ± 1.5, 19.1 ± 1.4, 19.9 ± 1.7 and 20.3 ± 0.7 mmHg, each significantly different from the fellow placebo eyes. Significant miosis also occurred (mean pupil size 1.0 ± 0.1 mm in the morning study). Evening instillation produced less daily fluctuation in IOP than morning instillation.

Watch out: Population mismatch is on the face of this card: these are laboratory Beagles with inherited primary OPEN-angle glaucoma, not client-owned dogs with primary angle-closure glaucoma, and there were only eight of them. The record does not state that IOP measurement was masked/blinded — masking is not established by this record, only random allocation of eyes is. Treatment lasted five days and the endpoint is IOP, a surrogate, not vision retention or time to glaucoma failure.

Gelatt KN, MacKay EO. Effect of different dose schedules of latanoprost on intraocular pressure and pupil size in the glaucomatous Beagle. Vet Ophthalmol. 2001;4(4):283-8. PMID: 11906665. Registry ID: none in the record. MeSH: Animals · Antihypertensive Agents · Dog Diseases · Dogs · Drug Administration Schedule · Female · Glaucoma, Open-Angle · Intraocular Pressure · Latanoprost · Male · Ophthalmic Solutions · Prostaglandins F, Synthetic · Pupil

Gelatt & MacKay 2004: travoprost, another prostaglandin analogue, lowered IOP by roughly 19–28 mmHg vs placebo in the same Beagle model

Randomized Controlled Trial (record's publication type); fellow-eye placebo control

Who: Dogs: eight laboratory glaucomatous Beagles (the same inherited-glaucoma laboratory model — not client-owned primary angle-closure patients); 0.004% travoprost was instilled in one eye and 0.5% methylcellulose (as placebo) in the fellow control eye, in three 5-day multiple-dose studies (once in the morning, once in the evening, or twice daily).

Result: Mean ± SEM diurnal changes from baseline IOP in control/placebo eyes across the three studies ranged from 1.2 ± 0.3 to 3.2 ± 0.9 mmHg. After 0.004% travoprost at 8 am once daily for four days, mean diurnal IOP changes were 19.0 ± 2.7, 24.7 ± 2.7, 24.9 ± 3.1 and 24.7 ± 3.1 mmHg; after 8 pm instillation, 23.5 ± 2.2, 24.2 ± 2.2, 24.5 ± 2.3 and 24.2 ± 2.3 mmHg; and with twice-daily instillation, 27.7 ± 2.1, 28.1 ± 2.1, 28.4 ± 2.2 and 28.5 ± 2.2 mmHg — each significantly different from the control eye. Miosis of varying duration was frequent.

Watch out: Same limits as the latanoprost card: eight laboratory Beagles with inherited glaucoma (the record's MeSH indexes this simply as Glaucoma), five days, IOP only, and no statement in the record that measurement was masked/blinded. This card shows a class effect in the model; it is not a head-to-head comparison of travoprost against latanoprost.

Gelatt KN, MacKay EO. Effect of different dose schedules of travoprost on intraocular pressure and pupil size in the glaucomatous Beagle. Vet Ophthalmol. 2004;7(1):53-7. PMID: 14738508. Registry ID: none in the record. MeSH: Administration, Topical · Animals · Cloprostenol · Dog Diseases · Dogs · Drug Administration Schedule · Female · Glaucoma · Intraocular Pressure · Male · Manometry · Ophthalmic Solutions · Prostaglandins F, Synthetic · Pupil · Severity of Illness Index · Travoprost

Dees 2014 (context): in real primary angle-closure patients, no prophylactic drop statistically beat the others; latanoprost's median time to medical failure was 284 days

Multicenter retrospective study — context card (not a randomised comparison)

Who: Dogs: 88 client-owned canine patients at multiple centres presenting with unilateral acute congestive primary angle-closure glaucoma (IOP > 25 mmHg) whose contralateral, still non-glaucomatous eye (with pectinate ligament dysplasia and/or a narrow or closed iridocorneal angle on gonioscopy) received prophylactic antiglaucoma medication; the most common pure-breds were the American Cocker Spaniel (20.4%) and Basset Hound (11.36%).

Result: The longest estimated median time to medical failure was for demecarium bromide 0.125% at 330.0 days, followed by latanoprost 0.005% at 284.0 days, dorzolamide hydrochloride 2.0% at 272.5 days, and demecarium bromide 0.25% at 143.0 days. Estimated median time to medical failure was 324.0 days for eyes receiving topical antiglaucoma plus anti-inflammatory medication vs 195.0 days for antiglaucoma medication alone. Survival analysis showed no statistical significance: none of the four antiglaucoma medications statistically delayed medical failure compared with the others.

Watch out: Retrospective and non-randomised — treatment choice was the clinician's, so these medians are context, not a comparative verdict. This is also a prophylaxis question (the at-risk fellow eye), not treatment of an eye already in angle-closure crisis. It is carded because it is the record that actually studies client-owned primary angle-closure dogs, and it does not confirm any first-line drop's superiority.

Dees DD, Fritz KJ, Maclaren NE, Esson DW, Sheehan Gaerig AM, Atkins RM, Knollinger AM. Efficacy of prophylactic antiglaucoma and anti-inflammatory medications in canine primary angle-closure glaucoma: a multicenter retrospective study (2004-2012). Vet Ophthalmol. 2014;17(3):195-200. PMID: 23826812. Registry ID: none in the record. MeSH: Administration, Topical · Animals · Anti-Inflammatory Agents · Antihypertensive Agents · Carbonic Anhydrase Inhibitors · Cholinesterase Inhibitors · Dog Diseases · Dogs · Female · Glaucoma, Angle-Closure · Intraocular Pressure · Latanoprost · Male · Prostaglandins F, Synthetic · Quaternary Ammonium Compounds · Retrospective Studies · Sulfonamides · Thiophenes

Synthesis: prostaglandin analogues clearly lower IOP in the laboratory Beagle glaucoma model; superiority in client-owned angle-closure dogs is unproven

Synthesis

Who: Synthesis of the cards above: Gelatt & MacKay 2001 (latanoprost, 8 laboratory Beagles with inherited primary open-angle glaucoma, fellow-eye placebo), Gelatt & MacKay 2004 (travoprost, same model), and Dees 2014 (retrospective context in 88 client-owned dogs with primary angle-closure glaucoma).

Result: Against a vehicle fellow eye, latanoprost and travoprost each produced large, significant, sustained diurnal IOP falls — on the order of 20–26 mmHg for latanoprost and 19–28 mmHg for travoprost over four treatment days, against placebo-eye changes of only a few mmHg. That is a convincing pharmacological effect in the model. But the question as posed is about primary angle-closure glaucoma in patients, and the only record in that actual population (Dees 2014, retrospective prophylaxis in the fellow eye) found no statistically significant difference between latanoprost, demecarium bromide and dorzolamide in time to medical failure. The honest claim is therefore: prostaglandin analogues lower IOP powerfully in glaucomatous dogs under laboratory conditions; that latanoprost lowers IOP more than other first-line drops in client-owned angle-closure disease has not been shown.

Watch out: Do not let the size of the Beagle IOP falls carry a clinical superiority claim: eight laboratory dogs, five days, an open-angle model, unmasked measurement as far as the records establish, and a surrogate endpoint. Angle anatomy also matters in angle-closure disease in a way the open-angle model cannot capture.

Synthesis of Gelatt KN & MacKay EO (PMID: 11906665), Gelatt KN & MacKay EO (PMID: 14738508) and Dees DD et al. (PMID: 23826812). Registry ID as on the individual cards.

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