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Source overview
Recorded excerpts for one species. Each dose remains a separate source entry; no regimen is selected.
Choose one species to view its source overview. All-species evidence remains available below.
View full clinical evidence and sources ↓Clinical evidence
Pending clinical review (PROPOSED)Rule-based (RULE_BASED)— applies to the facts and dose entries in this species selection; individual source records retain their own status.
Indications2
Add-on for refractory epilepsy; may be used as monotherapy for initial treatment
DogExtra-label (EXTRA_LABEL)1 source record · View provenance
- Dog · Plumb's Veterinary Drug Handbook, 7th ed., p. 1185–1186; Saunders Handbook of Veterinary Drugs (Papich), 4th ed., p. 862–864 — Indications table · Not applicable · Extra-label (EXTRA_LABEL) · Pending clinical review (PROPOSED) · Rule-based
Original excerpt: Add-on for refractory epilepsy; may be used as monotherapy for initial treatment — Extra-label
- Dog · Plumb's Veterinary Drug Handbook, 7th ed., p. 1185–1186; Saunders Handbook of Veterinary Drugs (Papich), 4th ed., p. 862–864 — Indications table · Not applicable · Extra-label (EXTRA_LABEL) · Pending clinical review (PROPOSED) · Rule-based
Refractory seizures — dose regimens not well defined
CatExtra-label (EXTRA_LABEL)1 source record · View provenance
- Cat · Plumb's Veterinary Drug Handbook, 7th ed., p. 1185–1186; Saunders Handbook of Veterinary Drugs (Papich), 4th ed., p. 862–864 — Indications table · Not applicable · Extra-label (EXTRA_LABEL) · Pending clinical review (PROPOSED) · Rule-based
Original excerpt: Refractory seizures — dose regimens not well defined — Extra-label
- Cat · Plumb's Veterinary Drug Handbook, 7th ed., p. 1185–1186; Saunders Handbook of Veterinary Drugs (Papich), 4th ed., p. 862–864 — Indications table · Not applicable · Extra-label (EXTRA_LABEL) · Pending clinical review (PROPOSED) · Rule-based
Dose regimens3
This calculator performs arithmetic only on the sourced dosing field shown for each result — it does not verify the field's accuracy, does not select which field to use for a patient, and does not replace a veterinarian's order. Not for clinical use. Confirm every result against the primary source before dispensing.
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Adverse effects139
Sedation, ataxia, inappetence — Reported, usually transient
DogNot applicable (NOT_APPLICABLE)1 source record · View provenance
- Dog · Plumb's Veterinary Drug Handbook, 7th ed., p. 1185–1186; Saunders Handbook of Veterinary Drugs (Papich), 4th ed., p. 862–864 — Side Effects / Adverse Effects table · Not applicable · Not applicable (NOT_APPLICABLE) · Pending clinical review (PROPOSED) · Rule-based
Liver injury (rare) — Possible — monitor
DogNot applicable (NOT_APPLICABLE)1 source record · View provenance
- Dog · Plumb's Veterinary Drug Handbook, 7th ed., p. 1185–1186; Saunders Handbook of Veterinary Drugs (Papich), 4th ed., p. 862–864 — Side Effects / Adverse Effects table · Not applicable · Not applicable (NOT_APPLICABLE) · Pending clinical review (PROPOSED) · Rule-based
Inappetence, diarrhea, vomiting, ataxia, somnolence — ~50% of cats at 20 mg/kg/day in one study
CatNot applicable (NOT_APPLICABLE)1 source record · View provenance
- Cat · Plumb's Veterinary Drug Handbook, 7th ed., p. 1185–1186; Saunders Handbook of Veterinary Drugs (Papich), 4th ed., p. 862–864 — Side Effects / Adverse Effects table · Not applicable · Not applicable (NOT_APPLICABLE) · Pending clinical review (PROPOSED) · Rule-based
These are counts of spontaneously reported events, not proven adverse effects, causal relationships, or incidence rates.
Bars compare report counts within each species; they do not show incidence.
More reportsFewer reportsDog
- Seizure NOS110 reports
- Vomiting42 reports
- Lethargy (see also Central nervous system depression in 'Neurological')31 reports
- Death by euthanasia30 reports
- Diarrhoea29 reports
- Ataxia25 reports
- Lethargy (see also Central nervous system depression in Neurological)23 reports
- Anorexia20 reports
- Lack of efficacy - NOS20 reports
- Not eating19 reports
- Other abnormal test result NOS18 reports
- Death15 reports
Cat
- INEFFECTIVE, SEIZURES3 reports
- Seizure NOS3 reports
- Anaphylaxis1 reports
- Anorexia1 reports
- Application site bruising1 reports
- Application site haematoma1 reports
- Application site irritation1 reports
- Application site pain1 reports
- Arthritis1 reports
- Behavioural disorder NOS1 reports
- Breathing difficulty1 reports
- Capsules, Abnormal1 reports
Monitoring1
Seizure frequency; liver enzymes periodically. Suggested effective plasma range 10–40 mcg/mL (not routinely available/validated in most labs).
Species not recordedNot applicable (NOT_APPLICABLE)1 source record · View provenance
- Species not recorded · Plumb's Veterinary Drug Handbook, 7th ed., p. 1185–1186; Saunders Handbook of Veterinary Drugs (Papich), 4th ed., p. 862–864 — Monitoring Parameters · Not applicable · Not applicable (NOT_APPLICABLE) · Pending clinical review (PROPOSED) · Rule-based
Contraindications1
Hypersensitivity to zonisamide or sulfonamides
Species not recordedNot applicable (NOT_APPLICABLE)1 source record · View provenance
- Species not recorded · Plumb's Veterinary Drug Handbook, 7th ed., p. 1185–1186; Saunders Handbook of Veterinary Drugs (Papich), 4th ed., p. 862–864 — Contraindications & Warnings table · Not applicable · Not applicable (NOT_APPLICABLE) · Pending clinical review (PROPOSED) · Rule-based
Precautions4
Sulfonamide-related reactions (KCS) theoretically possible though not yet reported
Species not recordedNot applicable (NOT_APPLICABLE)1 source record · View provenance
- Species not recorded · Plumb's Veterinary Drug Handbook, 7th ed., p. 1185–1186; Saunders Handbook of Veterinary Drugs (Papich), 4th ed., p. 862–864 — Contraindications & Warnings table · Not applicable · Not applicable (NOT_APPLICABLE) · Pending clinical review (PROPOSED) · Rule-based
Because it's a sulfonamide derivative, screen history for prior sulfa hypersensitivity before starting.
Species not recordedNot applicable (NOT_APPLICABLE)1 source record · View provenance
- Species not recorded · Plumb's Veterinary Drug Handbook, 7th ed., p. 1185–1186; Saunders Handbook of Veterinary Drugs (Papich), 4th ed., p. 862–864 — Clinical pearl · Not applicable · Not applicable (NOT_APPLICABLE) · Pending clinical review (PROPOSED) · Rule-based
Tolerance with reduced efficacy can develop after 2–3 months of chronic use — counsel owners this is possible.
Species not recordedNot applicable (NOT_APPLICABLE)1 source record · View provenance
- Species not recorded · Plumb's Veterinary Drug Handbook, 7th ed., p. 1185–1186; Saunders Handbook of Veterinary Drugs (Papich), 4th ed., p. 862–864 — Clinical pearl · Not applicable · Not applicable (NOT_APPLICABLE) · Pending clinical review (PROPOSED) · Rule-based
Generics now available, improving cost-accessibility relative to earlier years.
Species not recordedNot applicable (NOT_APPLICABLE)1 source record · View provenance
- Species not recorded · Plumb's Veterinary Drug Handbook, 7th ed., p. 1185–1186; Saunders Handbook of Veterinary Drugs (Papich), 4th ed., p. 862–864 — Clinical pearl · Not applicable · Not applicable (NOT_APPLICABLE) · Pending clinical review (PROPOSED) · Rule-based
Interactions1
Phenobarbital — ↑ zonisamide clearance/↓ half-life — higher zonisamide doses needed in combination; effect persists ~10 weeks post-phenobarbital discontinuation
Species not recordedNot applicable (NOT_APPLICABLE)1 source record · View provenance
- Species not recorded · Plumb's Veterinary Drug Handbook, 7th ed., p. 1185–1186; Saunders Handbook of Veterinary Drugs (Papich), 4th ed., p. 862–864 — Drug Interactions table · Not applicable · Not applicable (NOT_APPLICABLE) · Pending clinical review (PROPOSED) · Rule-based
Pharmacokinetics4
Bioavailability — ~70%, low protein binding
DogNot applicable (NOT_APPLICABLE)1 source record · View provenance
- Dog · Plumb's Veterinary Drug Handbook, 7th ed., p. 1185–1186; Saunders Handbook of Veterinary Drugs (Papich), 4th ed., p. 862–864 — Pharmacokinetics table · Not applicable · Not applicable (NOT_APPLICABLE) · Pending clinical review (PROPOSED) · Rule-based
Half-life — ~15h (dog); shortened with concurrent phenobarbital; ~33h (cat)
DogNot applicable (NOT_APPLICABLE)1 source record · View provenance
- Dog · Plumb's Veterinary Drug Handbook, 7th ed., p. 1185–1186; Saunders Handbook of Veterinary Drugs (Papich), 4th ed., p. 862–864 — Pharmacokinetics table · Not applicable · Not applicable (NOT_APPLICABLE) · Pending clinical review (PROPOSED) · Rule-based
Metabolism — ~20% hepatic; majority renal excretion
Species not recordedNot applicable (NOT_APPLICABLE)1 source record · View provenance
- Species not recorded · Plumb's Veterinary Drug Handbook, 7th ed., p. 1185–1186; Saunders Handbook of Veterinary Drugs (Papich), 4th ed., p. 862–864 — Pharmacokinetics table · Not applicable · Not applicable (NOT_APPLICABLE) · Pending clinical review (PROPOSED) · Rule-based
Elimination — Primarily renal
Species not recordedNot applicable (NOT_APPLICABLE)1 source record · View provenance
- Species not recorded · Plumb's Veterinary Drug Handbook, 7th ed., p. 1185–1186; Saunders Handbook of Veterinary Drugs (Papich), 4th ed., p. 862–864 — Pharmacokinetics table · Not applicable · Not applicable (NOT_APPLICABLE) · Pending clinical review (PROPOSED) · Rule-based
Pregnancy / lactation considerations1
Known teratogen in dogs — ventricular septal defects, cardiomegaly, valvular/arterial anomalies at 30 mg/kg/day (plasma threshold ~25 mcg/mL). Avoid in pregnancy unless owner accepts significant risk. Unknown if excreted in milk — use caution.
Species not recordedNot applicable (NOT_APPLICABLE)1 source record · View provenance
- Species not recorded · Plumb's Veterinary Drug Handbook, 7th ed., p. 1185–1186; Saunders Handbook of Veterinary Drugs (Papich), 4th ed., p. 862–864 — Pregnancy & Lactation · Not applicable · Not applicable (NOT_APPLICABLE) · Pending clinical review (PROPOSED) · Rule-based
Literature references14
References are linked to this drug. Species applicability is not recorded here, so the species filter does not narrow this list. Imported dates do not retain their original precision; confirm dates in the original citation.
- Efficacy of monotherapy with zonisamide and proposed reference interval in dogs with epilepsy: a cohort of 207 dogs (2011-2021).
Study summary not available in the imported record. Open the original citation to review the study.
- Clinical efficacy and tolerability of zonisamide monotherapy in dogs with newly diagnosed idiopathic epilepsy: Prospective open-label uncontrolled multicenter trial.
Study summary not available in the imported record. Open the original citation to review the study.
- Immune-mediated polyarthritis and anterior uveitis secondary to zonisamide administration in a dog with refractory epilepsy.
Study summary not available in the imported record. Open the original citation to review the study.
- Efficacy evaluation of a commercially available MCT enriched therapeutic diet on dogs with idiopathic epilepsy treated with zonisamide: a prospective, randomized, double-blinded, placebo-controlled, crossover dietary preliminary study.
Study summary not available in the imported record. Open the original citation to review the study.
- Safety and efficacy of cannabidiol-cannabidiolic acid rich hemp extract in the treatment of refractory epileptic seizures in dogs.
Study summary not available in the imported record. Open the original citation to review the study.
Sources: PubMed, National Library of Medicine; openFDA, U.S. Food and Drug Administration; Plumb DC. Plumb's Veterinary Drug Handbook. 7th ed. PharmaVet Inc; 2011.
Owner information handout
Plain-language medication information to review with the owner. Open the handout to print it or download a PDF.