Pentoxifylline (Trental®, PTX) for Dogs and Cats

Overview of Pentoxifylline for Dogs and Cats

Pentoxifylline, also known as Trental® or PTX, is a hemorheologic agent that acts to improve blood flow by decreasing blood viscosity and increasing red cell flexibility. It is used in dogs for frostbite, thromboembolism, atopic dermatitis, contact allergies, and ulcerative dermatosis.
Pentoxifylline also increases leukocyte deformability and inhibits neutrophil adhesion and activation. It finds its main application in the treatment of disorders of the microcirculation. In such conditions, pentoxifylline may improve tissue blood flow, tissue oxygenation, and tissue viability.
Conditions in which pentoxifylline may be beneficial include endotoxic shock, other refractory forms of shock, certain skin conditions, and various types of thrombosis/microthrombosis . Pentoxifylline also has some immunomodulatory activity and has found application in the treatment of allergies.
Pentoxifylline is a prescription drug and can only be obtained from a veterinarian or by prescription from a veterinarian.
This drug is not approved for use in animals by the Food and Drug Administration but it is prescribed legally by veterinarians as an extra-label drug.

This drug is registered for use in humans only.
Human formulations: Trental® (Hoechst Marion Rousel) and Pentoxifylline Extended-Release (Purepac).
Veterinary formulations: None

Pentoxifylline is used for the treatment of:

Refractory/”irreversible” shock (e.g. endotoxic shock)
Various dermatologic conditions, including atopic dermatitis, contact allergies, ulcerative dermatosis of Collies, and ear margin necrosis
Canine dermatomyositis
Renal vasculitis (Greyhounds)
Thromboembolism
Frost bite

While generally safe and effective when prescribed by a veterinarian, pentoxifylline can cause side effects in some animals.
Pentoxifylline should not be used in animals that are intolerant to it or methylxanthenes (e.g. theophylline, theobromine) or in those that have previously displayed anaphylactoid reactions to it.
Pentoxifylline should not be used in pregnant animals
It is contraindicated in patients with cerebral or retinal hemorrhage and should be used only with great caution in patients with severe liver or kidney problems, or bleeding disorders.
Adverse reactions to pentoxifylline include: cardiac arrhythmias, edema, hypotension, dyspnea, vomiting, intestinal gas/bloat, tremor, liver dysfunction, anxiety, nasal congestion, pruritus, urticaria, conjunctivitis, and malaise.
During treatment it is recommended to monitor a blood clotting time (PT), arterial blood pressure, and liver enzymes.

When administered along with certain other drugs, interactions may occur.
Pentoxifylline may increase bleeding when used with anticoagulants, such as warfarin.
Theophylline blood levels are increased by pentoxifylline, so theophylline toxicity may occur when these two drugs are administered concomitantly.
Pentoxifylline may increase the hypotensive effects of antihypertensive drugs.

Medication should never be administered without first consulting your veterinarian.
The dosage prescribed may vary depending on the reason for prescribing. Dosing frequency may range from every 8 hours to every other day.
The duration of administration depends on the condition being treated, response to the medication and the development of any adverse effects. Be certain to complete the prescription unless specifically directed by your veterinarian. Even if your pet feels better, the entire treatment plan should be completed to prevent relapse.
In dogs, the usual dose is 5 to 12.5 mg per pound (10 to 25 mg/kg) every 12 to 24 hours.
In cats, 100 mg per cat every 12 hours has been recommended.