here you go Cajun .
SIDE EFFECTS
Side effects are not a concern with the extremely low doses used in commercially marketed heartworm preventives.
Problems may arise when higher doses, such as those used against skin mites, are employed but even then, side effects generally do not occur with any anti-mange doses of ivermectin except in animals with genetic sensitivity. Such individuals are usually Collies, Shetland sheepdogs, Australian shepherds, and Old English sheepdogs, though some individual animals that are not members of these sensitive breeds may also be prone to side effects. Very low test doses are often recommended to identify thes individuals regardless of their breed. Alternatively, a blood test is available to test for genetic sensitivity (see below).
Collies with ivermectin sensitivity have been found to have a mutant gene for what is called the "P-glycoprotein." The P-glycoprotein has been studied largely because overexpression of this protein (i.e. having more of it than normal) results poor function of chemotherapy drugs in the treatment of cancer. The P-glycoprotein appears to be involved in keeping drugs out of certain body tissues. Having excess P-glycoprotein keeps chemotherapy drugs from reaching the tumor. When it comes to ivermectin sensitivity the problem is the opposite: mutant or non-functional P-glycoprotein leads to failure to keep certain drugs out of the central nervous system, allowing them access to sensitive tissue. Ivermectin side effects stem from ivermectin entering the central nervous system.
Approximately 35% of Collies have a genetic mutation creating a non-functional P-glycoprotein. This allows for ivermectin doses that would normally be blocked from the central nervous system to gain access to it. Other herding breeds as listed above also have a tendency to express this mutation. There is now a test for P-glycoprotein mutation so that ivermectin sensitive dogs can be identified. This is a DNA test using an oral swab. Test kits can be ordered directly from the Washington State University Veterinary School via
www.vetmed.wsu.edu/depts-vcplHeartworm preventive doses are so low that side effects are not produced even in ivermectin sensitive individuals.
Side effects of concern are: dilated pupils and drunken gait which can progress to respiratory paralysis and death if medication is not withdrawn and supportive care is not initiated
