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 in the treatment of 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 in the treatment
of 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.
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
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 closely monitored 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.