Pet Drug Reports

Melarsomine Dihydrochloride (Immiticide, Diroban)adverse event reports that FDA received

Active ingredient

The names in brackets are brand names with this active ingredient.

The openFDA records give the value "MSK" for the brand name and for the manufacturer name of each drug. FDA says that MSK means "masked". So the site cannot count a report for a brand.

Read this first. FDA says this about the data:

An API dataset query result cannot be used to estimate the risk associated with the product or compare one drug or device product with another. When looking at the results, be aware that there is no certainty that the reported drug or device caused the adverse event. This dataset should not be the sole source of information for clinical decision-making or other assumptions about the safety or effectiveness of a product. The adverse event may have been related to an underlying disease, other drugs used at the same time or other non-drug related sources.

FDA Center for Veterinary Medicine publishes these words. Source: Adverse Event Reports for Animal Drugs and Devices, read on . The data have the reports that FDA received through .

This page is not veterinary advice. For an animal that is ill, speak to a veterinarian.

Contacting a veterinarianHow to report to FDA

From December 1995 to June 2026, FDA received 23,942 adverse event reports that name a drug with melarsomine dihydrochloride as its active ingredient. Of the 23,942 reports, 22,744 (95%) are about dogs.

In January to March 2026, FDA received 163 reports that name this drug. The signs that appear in the largest number of the 23,942 reports are "Ineffective, heartworm adults" and "Lack of efficacy (endoparasite) - heartworm". A report is not proof that a drug caused a sign.

Reports that name this drug fell by 8.7% in the 12 months to June 2026, compared with the 12 months before. Reports for all animal drugs fell by 4.6% in the same periods. The newest months can get more reports in a later update. Reports about dogs are 95% of the reports that name this drug, and 72.6% of all reports.

Since the last update of the FDA data

The site recorded an update of the FDA data on . FDA changed these counts for January to March 2026:

  • All species: from 151 to 163.
  • Dog: from 147 to 159.

January to March 2026 is the latest closed quarter in the data. In that quarter FDA received 163 reports that name melarsomine dihydrochloride: 159 dog, 0 cat, 0 horse, 4 other or not given.

All updatesFeed of updates (RSS)

Signs that the reports list

A sign is a coded term from the report. The words in brackets are a plain gloss of the term. The percentage is the share of the 23,942 reports that list the sign. One report can list more than one sign.

The sign that is in the largest number of the reports comes first.

  1. Ineffective, heartworm adults[legacy FDA term: the product did not have the expected effect (heartworm adults)]17.6%4,219 reports
  2. Lack of efficacy (endoparasite) - heartworm[the product did not have the expected effect: heartworm]11.9%2,840 reports
  3. Vomiting11.4%2,737 reports
  4. Injection site swelling[swelling where the injection was given]9.6%2,302 reports
  5. Injection site pain[pain where the injection was given]6.2%1,483 reports
  6. Lethargy[unusually tired or inactive]5.6%1,336 reports
  7. Pain NOS[NOS: not otherwise specified]5.4%1,288 reports
  8. Anorexia[not eating]5.1%1,220 reports
  9. Diarrhoea[diarrhea]5%1,193 reports
  10. Ineffective, heartworm larvae[legacy FDA term: the product did not have the expected effect (heartworm larvae)]4.7%1,123 reports
  11. Depression[dull, quiet or withdrawn]4.6%1,095 reports
  12. Fever4.2%999 reports
  13. Death4%959 reports
  14. Elevated alanine aminotransferase (ALT)[a liver enzyme above the normal range]3.9%942 reports
Show the next 16 signs
  1. Cough3.9%938 reports
  2. Injection site lump[lump where the injection was given]3.9%928 reports
  3. Hypersalivation[drooling]3.7%894 reports
  4. Panting3.5%844 reports
  5. Polypnoea[fast breathing]2.8%676 reports
  6. Bloody diarrhoea[diarrhea with blood]2.7%652 reports
  7. Lack of efficacy - NOS[the product did not have the expected effect]2.6%617 reports
  8. Cardiac disorder NOS[heart problem, type not specified]2.5%588 reports
  9. Ataxia[unsteady, uncoordinated movement]2.3%559 reports
  10. Restlessness2.2%535 reports
  11. Vials, Damaged[a product quality report, not a sign in an animal]2.2%524 reports
  12. Weight loss2.2%519 reports
  13. Elevated serum alkaline phosphatase (SAP)[a liver and bone enzyme above the normal range]2.2%518 reports
  14. Dyspnoea[difficulty breathing]2.1%511 reports
  15. Anaphylaxis[sudden severe allergic-type reaction]2.1%499 reports
  16. Vocalisation[crying out or unusual noise]2%468 reports

The list shows 30 of 1,514 coded signs. A report is not proof that a drug caused a sign. Download all signs (CSV)

Reports by species

  • Dog95%22,744
  • Human exposure0.4%104
  • Other0.1%24
  • Catunder 0.1%8
  • Other Canidsunder 0.1%1

The share is of all 23,942 reports that name melarsomine dihydrochloride. The other reports give a different species or no species.

Reports for each month, Jul 2021 to Jun 2026

Dog3,927 reports. Largest count in one month: 107 (Mar 2022)
Cat3 reports

No chart: no month has 5 or more reports.

Horse0 reports

No chart: no month has 5 or more reports.

Other or not given102 reports. Largest count in one month: 7 (Oct 2022)

The month is the month in which FDA received the report. Each chart has its own scale. FDA says that a report can take 3 to 6 months to reach the public data. The newest months can get more reports in a later update.

Reports by year

  • Dog
  • Cat
  • Horse
  • Other or not given
Reports that name melarsomine dihydrochloride, by the year in which FDA received them and by species
YearDogCatHorseOther or not givenAll species
20263390010349
20257050014719
20247900018808
20236840015699
20229352030967
20211,02210231,046
20201,09700251,122
20191,02200271,049
20181,10600501,156
20171,14200631,205
20161,12110981,220
201597900821,061
201493000811,011
201387100116987
2012951002061,157
20119591034994
20101,13610241,161
20091,04000361,076
20089180044962
20077870059846
20068391031871
20056620029691
20047410052793
20034350016451
2002299100300
2001259003262
2000175003178
1999199000199
1998167000167
1997110001111
1996321000321
199530003

2026 has the reports that FDA received through Jun 2026. Download the years (CSV)

What the reports record

Outcome at the time of the report

  • Recovered/Normal7.2%1,725
  • Recovered with Sequela[recovered, with a lasting effect]3%724
  • Ongoing22.2%5,309
  • Died4.7%1,136
  • Euthanized0.8%182
  • Outcome Unknown25.6%6,125

An outcome in a report is not proof that the drug caused it. The person who sends the report gives the outcome. Each share is of the 23,942 reports that name melarsomine dihydrochloride.

A report about more than one animal can have more than one outcome.

Kind of report

  • Safety issue73.9%17,691
  • Lack of expected effectiveness19.5%4,661
  • Both safety and lack of expected effectiveness2.1%506
  • Manufacturing or product defect4.5%1,078
  • Otherunder 0.1%6

14,045 reports say if the event was serious. 66.4% of them have the serious flag. The person who sends the report sets the flag.

Show age, weight, breed and route

Age of the animal

  • Under 1 year0.6%155
  • 1 to 3 years42.3%10,132
  • 4 to 7 years33.3%7,971
  • 8 to 11 years11.2%2,690
  • 12 years and over1.9%459
  • Age not given10.6%2,535

Weight of the animal

  • Under 5 kg (11 lb)4.3%1,031
  • 5 to 9.9 kg (11 to 22 lb)10.8%2,597
  • 10 to 24.9 kg (22 to 55 lb)31.3%7,488
  • 25 to 44.9 kg (55 to 99 lb)37.9%9,066
  • 45 kg and over (99 lb and over)5.2%1,239
  • Weight not given10.5%2,521

Breed, where the report gives one breed

A breed with many animals has many reports.

Route in the report

  • Intramuscular86%20,593
  • Parenteral0.9%222
  • Subcutaneous0.8%188
  • Oral0.4%107
  • Ophthalmic0.1%30
  • Intravenous0.1%19

Each bar is on a scale of 0 to 100%.

Approved animal drugs with this active ingredient (FDA Green Book)

This section is reference data. It has no report count.

The openFDA records give the value "MSK" for the brand name and for the manufacturer name of each drug. FDA says that MSK means "masked". So the site cannot count a report for a brand.

Brand names

  • Immiticide
  • Diroban

What the Green Book records give

Applications with an approval in force
2
Approved species
Dogs
Dose forms
Liquid (Solution), Powder
Routes
Intramuscular
Sale
RX (prescription)
Earliest approval date in the records

The species, dose forms and routes are the words of the Green Book records for all the applications together. One product can have fewer. The label of a product gives its approved use.

Applications in the Green Book of 2 Nov 2026, pioneer applications (NADA) first
Brand nameActive ingredientsSponsorApproved speciesApplication
Immiticide Sterile PowderMelarsomine DihydrochlorideBoehringer Ingelheim Animal Health USA, Inc.DogsNADA 141-042
DirobanMelarsomine DihydrochlorideAnzac Animal Health, LLCDogsANADA 200-609

Next in the A to Z list

All drugs by active ingredient. Brand names A to Z

FDA pages for this drug

The site checked these addresses on . The links open in a new tab.

Cite this page

Pet Drug Reports. Melarsomine Dihydrochloride: adverse event reports that FDA received. https://petdrugreports.com/drug/melarsomine-dihydrochloride/ Source: FDA Center for Veterinary Medicine, openFDA Animal and Veterinary adverse event reports, export of . Reports received through .

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Where the data come from

The counts come from the openFDA Animal and Veterinary adverse event files, export of 30 Oct 2026. The files have the reports that the FDA Center for Veterinary Medicine received through 26 Jun 2026. The files mask brand and manufacturer names. The site counts a drug by the active ingredients that each record gives, and gives no count to a brand, an application or a company. Ingredient names and the lists of approved products follow the FDA Green Book of 2 Nov 2026. The site does not use the application number that a record has.

The site does not publish report text, lot numbers or details of a reporter. FDA's record is the authority. See how the site counts reports, the data sources and the corrections page.

Questions about these reports

Which brand are these reports about?

The openFDA records give the value "MSK" for the brand name and for the manufacturer name of each drug. FDA says that MSK means "masked". So the site cannot count a report for a brand. The Green Book section of this page lists the brand names with this active ingredient.

Do the reports show that the drug caused the signs?

No. FDA states this about the data.

When looking at the results, be aware that there is no certainty that the reported drug or device caused the adverse event.

The adverse event may have been related to an underlying disease, other drugs used at the same time or other non-drug related sources.

FDA Center for Veterinary Medicine. Source: Adverse Event Reports for Animal Drugs and Devices

How many reports did FDA receive in the latest 12 months?

FDA received 696 reports in the 12 months to June 2026. It received 762 reports in the 12 months before. FDA says that a report can take 3 to 6 months to reach the public data. The newest months can get more reports in a later update.

What kinds of report are in the count?

Of the 23,942 reports received from December 1995 to June 2026, 73.9% are about a safety issue only. 21.6% are about a lack of expected effectiveness, alone or with a safety issue. 4.5% are about a defect of the product or its package.