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Pentoxifylline for Veterinary Use
by Barbara Forney, VMD
Pentoxifylline is used in humans to treat peripheral vascular diseases and cerebrovascular disease caused by impairment of the microcirculation. It is similar chemically to theophylline and caffeine. Although its mechanism of action is not well understood, pentoxifylline is thought both to decrease the viscosity of blood and to increase the flexibility of red blood cells.
Pentoxifylline is used in dogs to improve microcirculation and as a consequence diminish inflammation and enhance healing of many kinds of skin lesions including: ulcerative dermatosis of Collies and Shelties, dermatomyositis, ear margin seborrhea, atopic disease, and other skin diseases with underlying vasculitis. Healing associated with microvascular compromise may take weeks to months before any appreciable difference is seen. There are some differences of opinion regarding dosing frequency. The standard recommendation is once a day or every other day although recent pharmacokinetic studies performed in the dog support dosing three times a day.
Pentoxifylline is used to treat endotoxemia, laminitis, and navicular disease in horses. Research in other species has shown improved survival rates for animals treated with this drug during sepsis. The underlying mechanism is thought to be through cytokine reduction. There is conflicting information regarding the concurrent use of pentoxifylline and NSAIDs (flunixin meglumine) when treating endotoxemia. Some studies support using both pentoxifylline and NSAIDs and some studies do not.
Recently there has been increased interest in the use of pentoxifylline to increase microcirculation to the foot to treat navicular disease and laminitis. The indications would be similar to those for isoxsuprine use. This use of pentoxifylline is based on extrapolation from work done on intermittent claudication in humans. Although there may be clinical benefits from the use of this drug, work by Fehr and Baxter shows that pentoxifylline and isoxsuprine do not increase blood flow to the digit or the laminae.
Pentoxifylline Side Effects
- Most of the information regarding side effects comes from reports on humans.
Vomiting and anorexia are the most-common side-effects seen in the dog. It may help to give pentoxifylline with a small amount of food.
- Less common side effects include tachycardia, headaches and central nervous system stimulation.
- Pentoxifylline should not be used in animals that are sensitive to other xanthines such as theophylline, theobromine or caffeine.
- Pentoxifylline should not be used in animals with cerebral or retinal hemorrhage or with increased risk of hemorrhage.
- Pentoxifylline should be used with caution in animals with diminished renal or hepatic function.
- There are no studies in domestic animals on the safety of pentoxifylline during pregnancy. Studies in laboratory animals did not show an increase in fetal malformations or losses except at very high doses (24x). Pentoxifylline is excreted in milk.
- Warfarin and other anticoagulants may increase risk of bleeding.
- Pentoxifylline is related to theophylline. Theophylline levels should be monitored closely if the drugs are used together.
- Ciprofloxacin and cimetidine may increase pentoxifylline levels.
Information on overdose in animals is not available. Signs associated with acute toxicity in humans include GI and CNS signs, hypotension, seizures, fever, cardiac arrhythmias and unconsciousness. Overdose should be treated with stomach emptying, activated charcoal and supportive care.
About the Author
Dr. Barbara Forney is a veterinary practitioner in Chester County, Pennsylvania. She has a master's degree in animal science from the University of Delaware and graduated from the University of Pennsylvania School of Veterinary Medicine in 1982.
She began to develop her interest in client education and medical writing in 1997. Recent publications include portions of The Pill Book Guide to Medication for Your Dog and Cat, and most recently Understanding Equine Medications published by the Bloodhorse.
Dr. Forney is an FEI veterinarian and an active member of the AAEP, AVMA, and AMWA.
You can purchase books by Dr. Forney at www.exclusivelyequine.com
Wedgewood Pharmacy's compounded veterinary preparations are not intended for use in food and food-producing animals.