SYMPTOMS.
Unless you are familiar with this condition, often the first sign is an apparently healthy rabbit lying limp in its cage. Upon examination, the rabbit has little or no movement of any limbs and just "flops" in your hands. Sometimes the only sign of life is the small "twitch" of the nose. If you are alert for the condition you can often spot the early signs before the rabbit has progressed to total paralysis. If a rabbit is sitting quietly in the corner of its cage (in no apparent distress) I give it a gentle push. If the rabbit falls over and finds it difficult to regain its feet I immediately suspect Paralysis or Flopsy. Sometimes a rabbit can still be hopping around the cage but its hop seems a little unsteady and unbalanced.
The progression of the condition can vary between rabbits. Sometimes a rabbit can be perfectly healthy and yet an hour later is dead in its cage! Other rabbits can gradually get worse over several hours and remain in a paralysed state for several days. Rabbits with a rapid onset of the condition can rarely be saved.
I have found that most of the rabbits I lose are between four to ten weeks of age - when the doe is weaning them. However other people have found that they seem to lose adult rabbits. A rabbit that has recovered from Flopsy seems to be susceptible at any future time of stress and any offspring appear to be more likely to be affected by it. It also seems as though this condition occurs in certain "lines" of rabbits - often ones with small gene pools
Some sort of diet deficiency seemed to be the most likely theory, possibly linked to certain lines of rabbits being "genetically" vulnerable to this deficiency. Murdoch University became involved and agreed to do tests on rabbits to see if they could discover any common factor. Rabbits that were affected by Flopsy, or died because of it were sent to the Uni for autopsy and tests.
Since rabbits treated with vitamin supplements sometimes recovered, breeders tried to discover which particular vitamin was the culprit. Early laboratory tests seemed to suggest a potassium deficiency and so rabbits were placed on banana diets!! However later tests seemed to discount this theory. Since hypocalcaemia (or low calcium) has similar symptoms many breeders began treating their affected rabbits with Calcium Sandos (an expensive and sticky treatment). This seemed to work sometimes but not always.
A BREAKTHROUGH.
Murdoch Uni found that some rabbits were deficient in Selenium but researchers found it difficult to find accurate base levels for these nutrients. By chance, an American vet visiting Murdoch University’s Veterinary School stated that in America they had found Vitamin E was necessary for the absorption of Selenium. Selenium is a mineral that functions as a part of an enzyme, glutathione peroxidase, that is involved in the removal or detoxification of peroxides, such as hydrogen peroxide, that are formed in tissues during normal metabolic processes. Vitamin E functions by acting as an inter – and intra – cellular antioxidant to prevent peroxide formation; thus Vitamin E and Selenium are very closely related in nutrition. The rabbit is interesting in that it apparently depends completely on Vitamin E for protection against peroxide damage. Both nutrients function by preventing tissue destruction by toxic peroxides formed during metabolism. In a deficiency of either Vitamin E or Selenium, tissue breakdown due to peroxide damage occurs. This results in destruction of muscle tissue (nutritional muscular dystrophy), infertility, reabsorption of foetuses and a variety of other effects..
AETIOLOGY
Vitamin E is an essential dietary requirement and one of its most important roles is as an inter – and intra – cellular antioxidant to prevent peroxide formation. In this capacity it prevents the oxidation of unsaturated lipid materials within cells. It is also logical to conclude that there is a positive correlation between fat input and vitamin E requirements to prevent peroxidation. The more active the cell – such as those of skeletal and involuntary muscles – the greater the inflow of lipids for energy supply and the greater the risk of damage if Vitamin E is limited. If skeletal muscles are involved, the effect is white muscle disease and the affected animals appear stiff or weak, often unable to rise or walk. If the myocardium (heart muscle) is affected, heart failure which appears as sudden unaccountable death usually results. Involvement of diaphragmatic or intercostals “breathing” muscles may lead to difficulty breathing and an accumulation of fluid in the lungs (secondary pneumonia).