Simparica Trio for Dogs Dose Calculator and Safety

Simparica Trio – One Chew Covers Almost Everything

Simparica Trio (Zoetis) is the most comprehensive single-product monthly preventive for dogs. Three active ingredients in one beef-flavored chew:

• Sarolaner (isoxazoline) – kills fleas + 5 tick species
• Moxidectin (macrocyclic lactone) – prevents heartworm
• Pyrantel pamoate – kills intestinal worms (roundworm + hookworm)

Questions This Calculator Answers

• “Which Simparica Trio size do I need?” – Weight-based size selection
• “Is Simparica Trio safe?” – Yes with FDA isoxazoline caveat
• “What does Simparica Trio prevent?” – Fleas, 5 tick species, heartworm, roundworm, hookworm
• “Is Simparica Trio better than NexGard Spectra?” – Equivalent coverage; brand preference
• “Is Simparica Trio safe for MDR1 breeds?” – Yes – moxidectin at HW dose is safe
• “How fast does Simparica Trio kill fleas?” – 3-8 hours; ticks 8-24 hours
• “Can Simparica Trio cause seizures?” – Rare – FDA isoxazoline class warning
• “What ages can take it?” – 8 weeks AND 2.8 lb (1.25 kg) minimum
• “Does it need a heartworm test?” – YES – annual heartworm test required

Size Chart

Size	Weight Range	Active Ingredients
Gold	2.8-5.5 lb (1.25-2.5 kg)	3 mg sarolaner + 0.06 mg moxidectin + 12.5 mg pyrantel
Purple	5.6-11 lb (2.5-5 kg)	6 + 0.12 + 25 mg
Caramel	11.1-22 lb (5-10 kg)	12 + 0.24 + 50 mg
Teal	22.1-44 lb (10-20 kg)	24 + 0.48 + 100 mg
Green	44.1-88 lb (20-40 kg)	48 + 0.96 + 200 mg
Brown	88.1-132 lb (40-60 kg)	72 + 1.44 + 300 mg

What’s Covered (and What’s NOT)

✓ Covered

• Adult fleas (Ctenocephalides felis)
• American dog tick (Dermacentor variabilis)
• Lone star tick (Amblyomma americanum)
• Black-legged tick (Ixodes scapularis) – Lyme vector
• Brown dog tick (Rhipicephalus sanguineus)
• Gulf Coast tick
• Heartworm (Dirofilaria immitis)
• Roundworm (Toxocara canis)
• Hookworm (Ancylostoma caninum)

❌ NOT Covered

• Whipworm (Trichuris vulpis) – use milbemycin (NexGard Spectra, Interceptor) or fenbendazole
• Tapeworm (Dipylidium, Echinococcus) – use praziquantel (Drontal Plus, Bayer Tapeworm)

Speed of Kill

• Fleas killed within 3-8 hours – fastest in isoxazoline class
• Ticks killed within 8-24 hours
• 35-day duration per chew

MDR1 Breed Safety

Simparica Trio is SAFE in MDR1-sensitive breeds (Collie, Australian Shepherd, Sheltie, Border Collie, Old English Sheepdog).

• Moxidectin at heartworm prevention dose is safe in MDR1 dogs (only HIGH-DOSE ivermectin is problematic)
• Sarolaner doesn’t cross blood-brain barrier significantly

⚠ FDA Isoxazoline Warning

Same class warning as NexGard, Bravecto, Credelio – rare neurologic adverse events (tremors, ataxia, seizures). Use cautiously in dogs with:

• Epilepsy
• Seizure history
• Unexplained collapse

Alternatives for seizure-prone dogs:

• Topical Frontline Plus + Seresto collar
• Separate heartworm prevention (Heartgard)
• Manual deworming as needed

Annual Heartworm Test REQUIRED

Before starting OR continuing Simparica Trio (or any heartworm preventive):

Why: undetected adult heartworm + macrocyclic lactone (moxidectin) can cause anaphylaxis from rapid microfilariae kill. American Heartworm Society + AAHA strongly recommend annual testing.

If heartworm positive: DO NOT start preventive without vet evaluation. Adult heartworm requires melarsomine treatment + strict cage rest first.

Side Effects (Mild and Uncommon)

Effect	Frequency
Vomiting	~2%
Diarrhea	~2%
Lethargy	~1%
Anorexia	~1%
Polyuria/polydipsia	Rare
Seizures, tremors, ataxia	RARE – FDA warning

Cost

• Per chew: $25-65 USA
• Annual: $300-780
• Vet prescription required
• Annual heartworm test included in vet visit

Compare to separate products:

• NexGard ($200-450) + Heartgard ($100-200) + intestinal worm coverage = $300-650
• Simparica Trio = $300-780 – similar or slightly more with convenience benefit

Administration Tips

• Give monthly – same date each month
• Give with food for best moxidectin absorption
• Verify dog ate the chew completely
• If vomits within 2 hours – repeat dose

Conclusion

Simparica Trio is a convenient all-in-one monthly preventive for flea + tick + heartworm + roundworm + hookworm in one chew. Doesn’t cover whipworm or tapeworm. MDR1-safe. FDA isoxazoline class warning for seizure-prone dogs. Annual heartworm test required. Cost-comparable to multiple separate products with convenience benefit.

Frequently Asked Questions

What does Simparica Trio cover?

SIMPARICA TRIO covers FOUR major parasite groups in one monthly chew:

1. FLEAS – adult Ctenocephalides felis killed within 3-8 hours via SAROLANER
2. FIVE TICK SPECIES – American dog tick (Dermacentor variabilis), lone star tick (Amblyomma americanum), black-legged/deer tick (Ixodes scapularis – Lyme disease vector), brown dog tick (Rhipicephalus sanguineus), Gulf Coast tick – killed within 8-24 hours via sarolaner
3. HEARTWORM PREVENTION – Dirofilaria immitis L3/L4 larvae killed via MOXIDECTIN before becoming adults
4. INTESTINAL WORMS – roundworm (Toxocara canis) + hookworm (Ancylostoma caninum) killed via PYRANTEL PAMOATE

NOT COVERED:

1. WHIPWORM (Trichuris vulpis) – need milbemycin (NexGard Spectra, Interceptor) or fenbendazole (Panacur)
2. TAPEWORM (Dipylidium caninum from fleas, Echinococcus from wildlife) – need praziquantel (Drontal Plus, Bayer Tapeworm Dewormer)
3. EAR MITES – sarolaner has off-label efficacy but not officially labeled
4. DEMODICOSIS, SARCOPTIC MANGE – sarolaner has off-label efficacy but use NexGard or vet-prescribed regimen for these conditions. CONVENIENT – one monthly chew replaces 3-4 separate products. EQUIVALENT to NEXGARD SPECTRA (which has milbemycin for heartworm + whipworm coverage but otherwise same scope). Choose Simparica Trio if you don’t need whipworm coverage; NexGard Spectra if you do. ANNUAL HEARTWORM TEST REQUIRED before starting/continuing

Is Simparica Trio safe for puppies?

YES – approved for puppies starting at 8 WEEKS of age AND 2.8 lb (1.25 kg) minimum weight. SMALLEST size GOLD covers 2.8-5.5 lb (1.25-2.5 kg)

FOR PUPPIES UNDER 8 WEEKS OR 2.8 lb – alternative parasite prevention needed:

1. For FLEAS in young puppies under 4 weeks – bathing with dish soap (Dawn) plus combing physically removes fleas (do NOT use insecticide on very young pups)
2. CAPSTAR (nitenpyram) approved 4 weeks + 2 lb – 24-hour flea kill
3. FRONTLINE PLUS approved 8 weeks
4. ADVANTAGE II approved 7 weeks
5. HEARTGARD approved 6 weeks

PRACTICAL APPROACH:

1. Use age-appropriate alternative until puppy reaches Simparica Trio minimum (8 weeks + 2.8 lb)
2. TRANSITION to Simparica Trio when minimum reached
3. Many puppies reach 2.8 lb by 8 weeks; tiny toy breed puppies may take longer

SAFETY in puppies same profile as adults: mild GI signs uncommon; rare neurologic events (FDA isoxazoline class warning); MDR1 safe. PUPPY GROWTH consideration – puppies grow rapidly; may need to UPGRADE Simparica Trio size between 8-26 weeks as puppy moves through weight bands; ensure you’re using correct size band for current weight not initial weight. PREGNANCY/LACTATION – Simparica Trio safety NOT established in breeding/pregnant/lactating dogs; use alternative (Heartgard for heartworm; Frontline Plus topical for fleas/ticks; veterinary guidance). VACCINATIONS during Simparica Trio – no interaction; can give vaccines + Simparica Trio without concern. DEWORMING from breeder – puppies often receive deworming at 2-4-6-8 weeks; Simparica Trio replaces this once puppy reaches threshold. WHIPWORM coverage missing – if puppy diagnosed with whipworm (Trichuris), Simparica Trio alone insufficient; needs fenbendazole or transition to NexGard Spectra/Interceptor Plus

Does Simparica Trio kill heartworm?

SIMPARICA TRIO PREVENTS heartworm but does NOT KILL ADULT heartworms. The MOXIDECTIN component kills HEARTWORM LARVAE (L3 stage from mosquito bite + L4 stage developing in tissues) BEFORE they become adult worms

THIS IS PREVENTION not treatment. HEARTWORM LIFECYCLE:

1. Mosquito bites infected dog, takes up microfilariae
2. Microfilariae develop into L3 larvae in mosquito over 2-4 weeks
3. Mosquito bites new dog, deposits L3 larvae
4. L3 → L4 → L5 (immature adult) over 6 months in tissues
5. Adult heartworms reach heart at 6-7 months
6. Adults live 5-7 years in heart causing disease

SIMPARICA TRIO MOXIDECTIN: kills L3 and L4 larvae – effectively preventing progression to adult heartworm. Given MONTHLY because L3 + L4 stages susceptible to macrocyclic lactones; effective up to ~45 days post-infection. IF MISSED DOSES + DOG INFECTED with adult heartworm – giving Simparica Trio (or any heartworm preventive) can cause ANAPHYLAXIS as the moxidectin kills circulating microfilariae rapidly; the dead microfilariae trigger massive immune response causing shock, collapse, death. THIS IS WHY ANNUAL HEARTWORM TESTING is required before starting/continuing any heartworm preventive

IF DOG TESTS POSITIVE for heartworm:

1. DO NOT start preventive without vet guidance
2. MELARSOMINE TREATMENT (Immiticide) needed to kill adult heartworms – 3-injection protocol over 60 days
3. STRICT CAGE REST 6 months during treatment
4. DOXYCYCLINE 28 days to kill Wolbachia bacteria
5. After successful adult treatment, then monthly preventive resumed

PREVENTION vs TREATMENT cost: prevention $300-780/year; treatment $1500-3000+ with significant morbidity. SIMPARICA TRIO is preventive not treatment – get annual heartworm test, continue monthly dosing, and don’t lapse coverage especially in endemic areas (Gulf Coast, Southeast USA, Mississippi Valley)

Is Simparica Trio better than NexGard Spectra?

EQUIVALENT COVERAGE in most categories; choice based on personal preference, brand availability, breed considerations, and price

COMPARISON: BOTH PRODUCTS – monthly chew; cover fleas + 5 tick species + heartworm + intestinal worms; isoxazoline-class active for flea/tick; FDA isoxazoline class warning applies to both; MDR1-safe at preventive doses

DIFFERENCES:

1. SIMPARICA TRIO uses SAROLANER (isoxazoline) + MOXIDECTIN (heartworm) + PYRANTEL (roundworm + hookworm); NEXGARD SPECTRA uses AFOXOLANER (isoxazoline) + MILBEMYCIN OXIME (heartworm + whipworm)
2. WHIPWORM COVERAGE – NexGard Spectra covers WHIPWORM (Trichuris vulpis) via milbemycin; Simparica Trio does NOT
3. FLEA KILL SPEED – Simparica Trio sarolaner kills fleas in 3-8 hours; NexGard Spectra afoxolaner kills in 8 hours – SIMPARICA SLIGHTLY FASTER
4. TICK SPECIES – both cover 5 common species
5. PALATABILITY – both beef-flavored, well-accepted by most dogs; some dogs prefer one over other
6. AVAILABILITY – varies by region; both widely available in USA
7. DURATION – both 35-day protection; given monthly
8. PRICE – similar; usually within $5-10/month of each other
9. MANUFACTURER – Simparica Trio by Zoetis; NexGard Spectra by Boehringer Ingelheim
10. AGE/WEIGHT minimums – both 8 weeks; NexGard Spectra 4.4 lb (2 kg) minimum vs Simparica Trio 2.8 lb (1.25 kg) – Simparica Trio approved smaller dogs

CHOOSE SIMPARICA TRIO if:

1. Faster flea kill desired
2. Very small dog (under 4.4 lb but over 2.8 lb)
3. Don’t need whipworm coverage (low whipworm exposure area, fenced yard)
4. Brand preference for Zoetis

CHOOSE NEXGARD SPECTRA if:

1. Need WHIPWORM coverage (recurrent whipworm history, soil exposure, high-risk area)
2. Brand preference for Boehringer Ingelheim/Merial
3. Slightly larger minimum weight (4.4 lb) not an issue. BOTH GOOD CHOICES – work with your vet to decide based on individual dog’s needs and your area’s parasite risks. ANNUAL HEARTWORM TEST required for either product. NEITHER COVERS TAPEWORM – need separate praziquantel if tapeworm exposure (flea infestation history, raw diet, hunting/wildlife exposure)

What are the side effects of Simparica Trio?

SIMPARICA TRIO IS GENERALLY WELL-TOLERATED with mild and infrequent side effects

COMMON SIDE EFFECTS (under 5%):

1. VOMITING ~2% – usually within 24 hours of dose; transient; if vomits within 2 hours of giving, repeat dose
2. DIARRHEA ~2% – typically mild, resolves in 1-2 days
3. LETHARGY ~1% – mild reduced energy 24-48 hours
4. ANOREXIA ~1% – decreased appetite briefly
5. POLYURIA/POLYDIPSIA – rare

UNCOMMON BUT POSSIBLE:

1. Pruritus (itching)
2. Hypersalivation
3. Tremors mild
4. Lameness
5. Skin reactions
6. Hyperactivity
7. Erythema

RARE BUT SERIOUS – FDA ISOXAZOLINE CLASS WARNING:

1. MUSCLE TREMORS
2. ATAXIA (uncoordinated movement)
3. SEIZURES
4. These are class effects of all isoxazolines (Bravecto, NexGard, Simparica, Credelio)
5. FDA Animal Drug Safety Communication September 2018 + updated 2021
6. Most events within hours-days of dose
7. Can occur in dogs with no prior seizure history

RISK FACTORS for neurologic events:

1. Pre-existing seizure disorder/epilepsy
2. Possibly small breeds + tiny doses (relatively higher mg/kg)
3. Liver disease affecting metabolism
4. Some breeds may be predisposed (genetic factors being studied)

MILD SIDE EFFECTS management:

1. Mild GI – give with food; usually resolves
2. Lethargy – monitor; recover within 24-48 hours typically
3. If concerning – contact vet

EMERGENCY signs requiring immediate vet:

1. Seizure activity
2. Severe weakness/collapse
3. Persistent vomiting > 24 hours
4. Bloody diarrhea
5. Severe anaphylactic-type reactions
6. Respiratory distress

REPORTING SIDE EFFECTS:

1. Contact your vet first
2. FDA online reporting portal for adverse drug events
3. Manufacturer (Zoetis) adverse event reporting
4. Helps build safety database. OVERDOSE – 5x label dose tolerated in safety studies; accidental double dose typically OK; significant overdose vet consultation

DRUG INTERACTIONS: minimal known; concurrent NSAIDs, steroids, antibiotics generally OK; verify with vet if dog on multiple medications. BENEFITS WEIGH AGAINST RISKS for most dogs – flea/tick/heartworm prevention prevents serious disease (Lyme, ehrlichiosis, Rocky Mountain Spotted Fever, heartworm-related cardiomyopathy/death). REASSESS if dog has neurologic event – switch to non-isoxazoline alternative. NEW RESEARCH ongoing about specific risk factors and mechanisms

How much does Simparica Trio cost?

USA PRICING varies by dog size + purchase channel: PER CHEW costs

1. GOLD (2.8-5.5 lb) USD 25-35
2. PURPLE (5.6-11 lb) USD 28-38
3. CARAMEL (11.1-22 lb) USD 30-42
4. TEAL (22.1-44 lb) USD 35-48
5. GREEN (44.1-88 lb) USD 40-55
6. BROWN (88.1-132 lb) USD 45-65

ANNUAL COST: $300-780/year

PURCHASE CHANNELS – typical price ranking high to low:

1. VET OFFICE – HIGHEST often 30-40% above online
2. PET STORE WITH PHARMACY – mid-range
3. ONLINE PHARMACIES (Chewy, 1-800-PetMeds, Petco Pharmacy, Amazon Pharmacy) – typically 20-40% cheaper than vet
4. BULK BUYING (12-month supply often discounted)
5. MANUFACTURER COUPONS available at zoetispetcare.com – $15-50 rebates possible

COMPARISON TO SEPARATE PRODUCTS:

1. NEXGARD ($25-45/month) + HEARTGARD ($15-20/month) + intestinal worm coverage = $480-780/year + occasional fecal testing
2. BRAVECTO ($60-90 every 3 months) + HEARTGARD ($15-20/month) = $400-540/year + flea/tick only every 3 months but doesn’t cover intestinal worms
3. FRONTLINE PLUS ($15-20/month) + HEARTGARD ($15-20/month) + occasional dewormer = $400-520/year + topical flea/tick
4. SERESTO COLLAR + HEARTGARD = $190-330/year for fleas/ticks/heartworm only. SIMPARICA TRIO usually MOST COMPREHENSIVE all-in-one at competitive price; convenience factor real

PET INSURANCE considerations:

1. Some plans cover wellness/preventives (extra cost)
2. Otherwise out-of-pocket
3. Don’t expect prevention coverage typically. PRESCRIPTION REQUIRED – vet must approve; online pharmacies will contact vet; annual heartworm test typically required

SAVINGS STRATEGIES:

1. Compare prices across pharmacies
2. Buy 12-month supply for discount
3. Manufacturer rebates
4. Combine with annual vet visit
5. Some vets offer in-house bundles

VALUE PROPOSITION:

1. Prevents Lyme, ehrlichiosis, Rocky Mountain Spotted Fever, heartworm disease, intestinal worms
2. Treatment of these diseases costs much more than prevention ($1500-3000+ for heartworm treatment alone)
3. Reduces risk of zoonotic disease transmission to humans (some intestinal worms zoonotic)
4. Insurance against parasite-related illness. CONCLUSION – cost-comparable to comprehensive separate-product approach with single-chew convenience

Related PuppaDogs Calculators

Continue building your dog’s personalised care plan with these related PuppaDogs calculators:

• Dog Pregnancy / Whelping Due-Date Calculator
• Puppy Weight Predictor (Adult Weight Calculator)
• Heatstroke Risk Calculator for Dogs
• Bloat (GDV) Risk Calculator for Dogs
• Dog Life Expectancy Calculator (Breed, Body Condition, Lifestyle)
• Spay/Neuter Timing Calculator for Dogs (Breed-Specific)

References & Further Reading

The dosing ranges and safety information on this page are drawn from the following veterinary references. Always defer to your own veterinarian and the manufacturer’s label for your specific product.

1. Zoetis Inc. – Simparica Trio product label and FOI summary.
2. FDA Center for Veterinary Medicine – Animal Drug Safety Communication: FDA Alerts Pet Owners and Veterinarians About Potential for Neurologic Adverse Events Associated with Certain Flea and Tick Products (2018, updated 2021).
3. Becskei C et al. Field efficacy of Simparica Trio against fleas and ticks.
4. Six RH et al. Efficacy of sarolaner against fleas and ticks.
5. Becker AC et al. Moxidectin in dogs – pharmacology and safety.
6. American Heartworm Society – heartworm prevention guidelines.
7. Companion Animal Parasite Council (CAPC) – flea/tick/heartworm guidelines.
8. Mealey KL. MDR1 gene mutations – macrocyclic lactone safety in herding breeds.
9. Plumb DC. Plumb’s Veterinary Drug Handbook – sarolaner, moxidectin, pyrantel pamoate.
10. Maddison JE et al. Small Animal Clinical Pharmacology.
11. AAHA – Heartworm Disease Guidelines.
12. PuppaDogs. Heartworm Risk & Prevention Calculator, NexGard Calculator, Deworming Schedule Calculator. puppadogs.com.