Vetdrugs 2.0Montelukast is a cysteinyl leukotriene-receptor antagonist developed for human allergic airway disease. Veterinary use is extra-label and largely empirical, principally in cats with selected inflammatory disorders. A biologic rationale exists for reducing leukotriene-mediated responses, but that rationale has translated inconsistently into clinical benefit in veterinary airway disease.
Group
Leukotriene receptor antagonist
Mechanism of Action
Montelukast antagonizes CysLT1 receptors activated by cysteinyl leukotrienes released from mast cells, eosinophils and other inflammatory cells. Receptor blockade can reduce leukotriene-associated smooth-muscle contraction, mucus signaling and vascular permeability. The resulting reduction in leukotriene signaling depends on receptor activation and the contribution of these pathways to the inflammatory response.
Dose Rates
Dogs
| Use / stage | Dose | Route | Schedule | Instructions |
|---|---|---|---|---|
| Investigational use | Reference only | PO | A single 40 mg/dog dose was studied in six male Labradors for pharmacokinetics. This is a study exposure, not a universal fixed dose or an efficacy-supported maintenance regimen. |
Cats
| Use / stage | Dose | Route | Schedule | Instructions |
|---|---|---|---|---|
| Feline asthma adjunct | 0.5–1 mg/kg | PO | Every 24 h | Anecdotal veterinary regimen with limited efficacy evidence; not for acute bronchospasm. |
| Chronic upper respiratory disease adjunct | 0.25–0.5 mg/kg | PO | Every 24 h | Anecdotal veterinary regimen with limited efficacy evidence; not for acute bronchospasm. |
| Mild inflammatory bowel disease adjunct | 0.5–1 mg/kg | PO | Every 24 h | Anecdotal veterinary regimen with limited efficacy evidence; not for acute bronchospasm. |
| Heartworm-associated respiratory disease adjunct | 2 mg/animal | PO | Every 24 h | Anecdotal adjunct intended to limit lung injury when an adult worm dies; effectiveness is unproven. |
Indications
- Empirical adjunctive treatment of selected feline asthma or chronic inflammatory airway disease, with clinical benefit unestablished and reported responses often disappointing.
- Empirical adjunctive treatment of selected feline inflammatory upper-airway disease, with anecdotal evidence only.
Contraindications
- Hypersensitivity
Interactions
- Phenobarbital or rifampin may lower exposure by enzyme induction.
- A human report links concomitant prednisone to edema; significance for animals is uncertain.
Adverse effects
- Veterinary adverse-event frequency is not established
Toxicity
No validated veterinary overdose threshold is established; assess the ingested product and provide supportive management.
Preparations
| Preparation | Form | Strength | Route |
|---|---|---|---|
| Singulair tablets 4 mg montelukast equivalent Montelukast equivalent supplied as sodium salt. The 4 and 5 mg presentations are chewable; review excipients. | Tablet | 4 mg / tablet | PO |
| Singulair tablets 5 mg montelukast equivalent Montelukast equivalent supplied as sodium salt. The 4 and 5 mg presentations are chewable; review excipients. | Tablet | 5 mg / tablet | PO |
| Singulair tablets 10 mg montelukast equivalent Montelukast equivalent supplied as sodium salt. The 4 and 5 mg presentations are chewable; review excipients. | Tablet | 10 mg / tablet | PO |
Monitoring and Administration
A small canine pharmacokinetic study used a single 40 mg oral dose per Labrador; it did not establish a general therapeutic dose or treatment efficacy.
Do not use as a replacement for emergency bronchodilation or established control therapy for airway disease.
Assess benefit explicitly if used in an investigational plan and discontinue ineffective treatment.
May be administered with or without food. Store at room temperature protected from moisture and light; assess response to each empirical indication. Equine airway-obstruction research did not establish benefit.