Sulfadimethoxine/Ormetoprim
Also known as: Primor, Rofenaid 40, Romet 30
- **Hydration is critical:** Ensure your pet has free access to fresh water at all times to prevent dehydration and the formation of urinary crystals. - **Watch the eyes:** Monitor for signs of "dry eye" (squinting, redness, thick mucoid discharge). Contact your veterinarian immediately if these occur, as this can cause permanent eye damage. - **Allergic reactions:** Stop the medication and contact your vet if you notice facial swelling, hives, vomiting, fever, joint pain, or severe lethargy. - Give the medication exactly as prescribed, and do not skip doses. Even if your pet looks better, finish the entire course to prevent bacterial resistance.
Dosage must be set by your veterinarian for your specific pet. Never give human medication or another pet’s prescription without veterinary guidance.
What it is used for
- Susceptible infections
- Susceptible infections (skin and soft tissue)
How it is given
Possible side effects
- Keratoconjunctivitis sicca (KCS/dry eye) - potentially irreversible
- Acute neutrophilic hepatitis with icterus
- Vomiting
- Anorexia
- Diarrhea
- Fever
- Hemolytic anemia
- Urticaria
- Polyarthritis
- Facial swelling
- Polydipsia and polyuria
- Cholestasis
- Hypersensitivity reactions (Type I anaphylaxis or Type III serum sickness)
- Hypothyroidism (with extended use)
Cautions & contraindications
- Hypersensitivity to sulfonamides, thiazides, or sulfonylurea agents
- Severe renal or hepatic impairment
- Marked liver parenchymal damage
- Blood dyscrasias
- Doberman Pinschers (highly susceptible to sulfonamide-induced poly-systemic immune complex disease)
- Use with caution in patients with pre-existing hepatic or thyroid disease, diminished renal function, urinary obstruction, or urolithiasis. Hypersensitivity reactions appear more common in large breed dogs. Potentially teratogenic (cleft palate reported in lab animals with TMP/sulfa); weigh risk versus benefit in pregnant animals.
Drug interactions
- Various (Refer to Trimethoprim/Sulfa): Specific interactions are not explicitly noted for this combination, but it is expected to share the interaction profile of trimethoprim/sulfa (e.g., potential antagonism with cyclosporine, increased risk of bleeding with anticoagulants).
Frequently asked questions
What is Sulfadimethoxine/Ormetoprim used for in pets?
- **Hydration is critical:** Ensure your pet has free access to fresh water at all times to prevent dehydration and the formation of urinary crystals. - **Watch the eyes:** Monitor for signs of "dry eye" (squinting, redness, thick mucoid discharge). Contact your veterinarian immediately if these occur, as this can cause permanent eye damage. - **Allergic reactions:** Stop the medication and contact your vet if you notice facial swelling, hives, vomiting, fever, joint pain, or severe lethargy. - Give the medication exactly as prescribed, and do not skip doses. Even if your pet looks better, finish the entire course to prevent bacterial resistance.
Is Sulfadimethoxine/Ormetoprim safe for my pet?
Dosage must be set by your veterinarian for your specific pet. Never give human medication or another pet’s prescription without veterinary guidance.
This article is for general education and is not a substitute for professional veterinary advice. If your pet is unwell, please consult a veterinarian.
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