Selegiline HCl

What is this medication for?

• Canine cognitive dysfunction ("old dog dementia"); pituitary-dependent hyperadrenocorticism (Cushing's — efficacy controversial)
• Feline cognitive dysfunction syndrome

How is it given?

Give exactly as your veterinarian prescribed — never change the dose or stop on your own unless your veterinarian has told you to.

What if I miss a dose?

• Give it as soon as you remember — unless it is almost time for the next dose (then skip the missed one; never double up).
• Call your clinic if you miss more than one dose in a row.

Side effects — what should I watch for?

Effects listed as common in this handout

• Vomiting, diarrhea (Reported)
• CNS effects: restlessness, repetitive movements, hyperactivity, low energy/tiredness (Reported, more likely at high doses (>0.3 mg/kg above label in some data))
• Diminished hearing/deafness, itching, licking, tremors (Reported)

Worth a phone call to your veterinarian

• Any new symptom that worries you.

⚠️ Contact your veterinarian or an emergency clinic IMMEDIATELY if you notice

• Trouble breathing, collapse, seizures, severe vomiting or diarrhea, facial swelling, or pale gums

Before starting (or refilling), tell your veterinarian if your pet:

• has or has had: Known hypersensitivity; not indicated for adrenal tumors (non-PDH Cushing's)
• has or has had: Confirm PDH diagnosis before treating for Cushing's — do not use for adrenal-dependent disease; potential for human abuse (amphetamine metabolites) — be alert for drug "shoppers"

• is pregnant, nursing, or used for breeding
• is taking any other medications, supplements, or flea/tick products, including:
  • Opioids (esp. meperidine)
  • SSRIs (fluoxetine), TCAs (clomipramine, amitriptyline), tramadol
  • Amitraz
  • Ephedrine, phenylpropanolamine, pseudoephedrine

Storage and handling

Veterinary tablets: controlled room temperature 20–25°C (68–77°F).

Good to know

• Efficacy for PDH Cushing's is considered inferior to trilostane or mitotane — set expectations accordingly; may only help lesions involving the pars intermedia.
• For cognitive dysfunction, benefit may take weeks to become apparent — don't judge failure too early.
• RCI Class 2 controlled substance for competition animals — relevant in performance/sporting dog contexts.