What is Immune Mediated Disease
Immune mediated sometimes called autoimmune disease is a general term used to describe many illnesses that result in the destruction of the body's own cells by the immune system
The immune system is extremely complex, it needs to be to protect the body from the millions of foreign pathogens it comes into contact with daily , bacteria or viruses are just two of them. The immune system is designed to recognise these pathogens as “non-self” or not belonging to the body and destroy them. It must also ignore anything that is “self”or belongs to the body. From day1 the immune system is capable of distinguishing which proteins belong to the body and which are foreign and must be destroyed.
Autoimmune disease results from a malfunction of the immune system, it sees the body's “self” proteins as foreign and starts to destroy them.
The results of this malfunction will depend on which parts of “self” the immune system has mistaken for “non-self” .It could be a protein on the surface of blood cells which it sets out to destroy, the result will be catastrophic anaemia as the immune system destroys the red blood cells faster than the body can replace them. If untreated death will be inevitable, this disease is autoimmune haemolytic anaemia. In most cases of Addison's disease the target is the Adrenal gland, the destruction of this gland results in severe illness and death if untreated.
As autoimmune diseases tend to run in families this would suggest they are hereditary or at least the predisposition (likelihood) to develop them is. The mode of inheritance may well be different in some breeds and its exact nature is still being researched. Whilst this is difficult enough it seems a “Trigger” of some kind is needed for the genetically predisposed dog to show symptoms and express the disease. “Triggers” can be just about anything that challenges the immune system and requires it to respond, infections, stress, drugs, hormones, vaccinations, in fact just about anything, the dog however must be genetically predisposed to develop such an illness before any “Trigger” factor will result in illness.
Implications for Breeding
Some animals may have been bred from before autoimmune disease manifests itself, if this is the case then breeders should contact the owners of any offspring.
It would be very unwise to breed from an affected dog even if they have recovered .
Matings that produced affected dogs should not be repeated.
It would be unwise to line breed from dogs known to have produced affected dogs
Early treatment is of the utmost importance if you suspect your dog may have an immune mediated disease, they become life-threatening very quickly and any delay in seeking veterinary help may be fatal.
Immune diseases are difficult to diagnose and sometimes it may be necessary to simply rule out anything else such as infection, your vet will advise on tests needed for diagnosis and referral to a specialist vet may well be necessary.
The treatment for these diseases is usually an initial high immune-suppressing dose of steroids, if this dose is not high enough the dog may relapse quickly or just not respond. The malfunctioning immune system must be suppressed to stop its destruction of the body's own proteins. Once this is achieved, which may be very quickly , the steroids can be very slowly reduced and hopefully stopped
Some dogs recover completely and can be steroid free, some recover only to relapse at some later date, some cannot be weaned off the medication.
In these cases the effects of long-term steroid use will have to be managed , the ideal being to keep the dog on the lowest dose possible with the dog showing no symptoms.
There is help and support available from owners who have had affected whippets.