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Trazodone is an oral sedative and treatment for mood and behavioral disorders and in mammals. This medication is a type of serotonin antagonist and reuptake inhibitor (SARI), which is slightly different from the more common class of antidepressants: selective serotonin reuptake inhibitors (SSRIs).

SARIs share many of the same functions as SSRIs with one major difference — SSRIs aren’t receptor antagonists. SSRIs and SARIs both inhibit neurons in the brain from absorbing serotonin, which allows these molecules to stay in the nerve synapses for longer. Unlike SSRIs, SARIs encourage neurotransmitters to attach to receptors associated with mood regulation. 

To truly understand how this drug works, you need to know about the biochemicals that make trazodone’s effects possible. Serotonin is a neurotransmitter that contributes to mood, hunger, sleep cues, and behavior in animals. 

Trazodone affects the way the brain regulates this neurotransmitter and helps it to bind to the more optimal receptor site. By manipulating serotonin’s activity within the neuropathway, trazodone induces relaxation, lowers anxiety, and stabilizes mood.

Dosage

The starting dose range for this medication is quite broad. Dosages between 1 mg and 8 mg /lb are considered acceptable, so long as the canine isn’t on additional SSRIs. Dogs taking SSRIs in combination with trazodone should receive a starting dose between 0.9 mg and 2.2 mg per pound, with the dosage never exceeding 6 mg.

Most canines start on a low dose of trazodone and gradually work up to the appropriate amount for their body. Finding the correct dosage of trazodone for dogs is complicated and may take some trial and error. 

Dosage instructions

Trazodone can be prescribed as needed or as a once-daily maintenance medication. If your dog requires this medication as needed for anxiety, give it to them at the first signs of a panic attack. Your vet may direct you to administer this medication before exposure to a known anxiety trigger, like a vet appointment or car ride.

Never crush Trazdone before administering. You should give your pet a small amount of food or some treats before offering this medication. An empty stomach speeds up the absorption of trazodone, which can amplify side effects like drowsiness, incoordination, and nausea.

Efficacy

One study found that trazodone for dogs had a bioavailability of nearly 85% when taken by mouth and noted no negative side effects in the study group. 

Researchers reviewed 56 separate case studies where trazodone was used to treat anxiety in canines and concluded that it was well tolerated in dogs of most breeds, sexes, and ages.

Side effects

  • Enlarged pupils

  • Nausea or vomiting

  • Poor muscle control

  • Irregular heartbeat

  • Unusual hunger

  • Mood and behavioral changes

  • Canine priapism

    (painful erections that last more than 4 hours)

  • Anxiousness

  • A sudden decrease in blood pressure

  • Drowsiness

  • Sleeping more often

  • Colorectal inflammation

  • Behavioral disinhibition

Considerations

Do not administer this medication to dogs who have taken an MAOI within the last two weeks. MAOIs exacerbate the effects of SARIs like trazodone, causing a surge of serotonin, which can overwhelm the neuropathways.

This rapid influx of neurotransmitters is called serotonin syndrome, a potentially deadly condition that can cause physiological and psychological impairment in canines and humans. Combining trazodone with selective serotonin reuptake inhibitors can also trigger serotonin syndrome.

High doses of trazodone during pregnancy were associated with fetal demise and deformities in living offspring. Pets with heart failure, glaucoma, low renal function, or liver failure should avoid this medication unless absolutely necessary. 

Signs of serotonin syndrome include:

  • Gastrointestinal upset

  • Dilated pupils

  • Slobbering 

  • Confusion

  • Unusual or excessive barking or other vocalizations 

  • Changes in mood or behavior

  • Seizures

  • Overheating

  • Loss of eyesight

  • Trouble breathing

  • Paralysis

  • Loss of consciousness

  • Coma 

  • Death

Drug interactions

Certain medications can magnify the effects of trazodone for dogs. Discuss the benefits and risks of this medication if your pet is on any of these drugs:

  • Blood pressure

    drugs

  • NSAIDs (including aspirin)

  • Certain antifungals

  • CNS depressants

  • MAOIs

  • Antidepressants

  • Synthetic opioids like tramadol

  • Fluoroquinolone antibiotics

  • Zofran

  • Phenothiazine antipsychotics

  • Benzamides

  • Antiarrhythmic medications (like digoxin)

  • Diuretics

  • Tricyclic antidepressants 

Allergic reactions and sensitivity

Rarely, trazodone can cause a sudden onset histamine response, resulting in both typical and atypical drug reaction symptoms. Some dogs develop a sensitivity to this drug after weeks, months, or even years of taking it without issue. 

Signs your dog may be hypersensitive to trazodone:

  • Significantly impaired coordination

  • Painful erections for longer than 4 hours

  • Confusion

  • Extreme sedation

  • Persistent diarrhea and vomiting

  • Agitation

  • Heightened anxiety

Frequently asked questions

Should dogs be tapered off trazodone?

Yes. Long-term use of this medication can sometimes cause withdrawal symptoms. Rather than stopping abruptly, talk to your vet about gradually reducing your dog’s dosage.  

Does my pet need to avoid dairy when taking trazodone?

No. Trazodone has no known dietary contraindications.

What are the signs of an overdose on trazodone for dogs?

Seizures, loss of consciousness, vomiting, and coma are all indications of a SARI drug overdose. Trazodone overdoses can be fatal. Have your dog evaluated by a vet if you believe they’ve ingested too much trazodone.

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