Identifying rabbit diseases and parasites

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  • Identifying rabbit diseases and parasites

    Reposting to preserve old pics and info, and also compiling it all into one big post.

    Been collecting as many images as I can of rabbit diseases and health conditions; as they are the most commonly-accessible animal that can be hunted and eaten in Australia; and are likely to be the first ferals that a newbie hunter is likely to encounter. Physically, they are similar in the same basic body structure to any larger mammal and many of the basic precautions in this thread can be applied to goats, kangaroos, cattle etc. I will continue to update this thread with more and better photos over time. Although many print and online resources address these issues, many of them are written from an academic or veterinary perspective and this thread aims to highlight things that are more observable under field conditions or are important from a hunter's perspective

    Introduction

    General

    - Rabbits can be infected with several diseases and parasitic conditions of which the most common and fatal in Australia are myxomatosis and rabbit calicivirus (also known as rabbit haemorrhagic disease (RHD).
    - However their presence in a population should not deter a recreational or pest shooter as rabbits reproduce rapidly and genetic resistance will spread in a population.
    - Rabbits can display no apparent symptoms but still be in the early stages of a disease. Luckily the scientific consensus is that such rabbits are not contagious until symptoms are observable.
    - If a rabbit is to be prepared for food, use commonsense and practice food hygiene and thorough cooking
    - External rabbit and hare parasites like fleas and mites do not generally affect humans - they can cause itchy bites while you are skinning or transporting a dead rabbit, but will not linger or survive as an infestation, or affect meat quality. However the flea species found on cats can survive on both rabbits and dogs.
    - Do not eat rabbits and hares that are found dead without an apparent cause. It may even have been poisoned.
    - Fresh roadkill is generally OK if the liver is still retrievable for examination for calicivirus and coccidiosis, and the head can be examined for myxomatosis. Cook these extremely thoroughly as internal parasites such as tapeworms are harder to detect in a crushed animal.
    - Keep your dogs, cats and other housepets up to date with deworming and vaccinations. This is especially important in working/hunting dogs and ferrets due to their increased exposure to disease.

    - Use this image as a reference for the appearance of a healthy rabbit's liver and kidneys. These belonged to an adult female rabbit...and soon to be Christmas lunch. The white specks here are just windblown grass seed and debris.



    Note the consistent, dark red colour of all lobes of the liver - the colour should be similar on the underside. At very close magnification, the liver has a fine reticulated pattern.
    Kidneys should be a pale greyish-pink.


    Part 1: Myxomatosis

    General information - http://en.wikipedia.org/wiki/Myxomatosis



    - When alive, affected rabbits move slowly and can be approached very closely; or sit near cover for long periods with their eyes closed and ears laid flat against their backs. Healthy rabbits can often do the latter but will become alert at the slightest stimuli, including the actions of other rabbits.
    - Rabbit is blind and walked slowly towards me and far away from any warren or other rabbits
    - it was shot behind the neck at point blank so that the appearance of head/facial features is retained...please disregard the blood on the fur.
    - Skinny and most likely dehydrated due to being unable to find food/water; a healthy rabbit should have a rounded belly
    - Fur has ruffled/coarse appearance, a healthy rabbit should appear sleek and fluffy
    - Blindness due to conjunctivitis, eyes are swollen shut and ooze fluid/pus which is often bloody
    - Nose may also be swollen/oozing
    - Incontinence can result in urine/fecal stains near rectum between hind legs.
    - Australian rabbits have become genetically disease resistant, meaning that large-scale mortality is uncommon. You are more likely to encounter isolated ill rabbits amidst healthy populations.
    - Affects hares very rarely (some sources claim not at all...)
    - Can be transmitted to pet or farmed rabbits by flea and mosquito bites
    - Not transmittable to humans or other pets/livestock, however I avoid eating obviously diseased animals as their weakened immune system often means they are carrying other more contagious disease and parasites.

    Second rabbit with myxomatosis:


    - Note puffy eyes and swellings.
    - Partial blindness. This rabbit kept turning to keep its better eye on me and was able to follow the movements of other rabbits.
    - As it still has partial vision, this rabbit could still find food,stay near a warren, and was not skinny
    - This may have prolonged its suffering as it has survived long enough to scratch the fur away around its eyes
    - Smaller swellings in ears are similar to myxo symptoms seen in hares. Hares can contract myxo but it us much less fatal for them and tends to resultin only skin swellings like these.

    Part 2: Coccidiosis




    More information: http://www.medirabbit.com/EN/GI_diseases/Protozoal_diseases/Cocc_en.htm

    - White or pale-yellow elongated spots on liver, eventually expanding and merging into a cheese-like mass. Healthy livers appear a rich, dark red and have no spots.
    - Spots are of harder texture than surrounding healthy tissue.
    - Externally, the rabbit can appear healthy and endure this condition for months; but under stressful conditions the infection flares up resulting in weight loss, diarrhoea and death
    - The liver is located just under the ribcage as shown in the second image, all lobes of the organ should be checked on both sides. You may spot a small, transparent yellow sack underneath one of the lobes. This is the gallbladder which is present in all rabbits and not an indicator of disease.
    - Coccidiosis is transmitted by contaminated food and water and more common in areas with high numbers of sheep and deer. Sheep, goats, pigs, deer and poultry can also contract and transmit coccidiosis.
    - Therefore knives and other tools exposed to infected rabbits and their feces should be cleaned very thoroughly.
    - A less severe form is intestinal coccidiosis, which can be caused by five different species of microbe and is more common in very young rabbits. The above link has detailed photographs and images of this condition also.
    - Coccidiosis is treatable by a vet but is otherwise fatal more often than not.
    - Rabbits with liver or intestinal spots may still be edible if weight loss has not yet occured, the flesh is still in good condition, and the live animal presents normal and vigorous behaviour.
    - However cooking must be thorough

    Part 3: Calicivirus / Rabbit haemorrhagic disease (RHD)



    Liver of rabbit with pale yallow-white areas associated with calicivirus infection. Whole lobe in foreground is inflamed and pale, pale streaks and mottling on other lobes. At top right of image, the clear yellow gall bladder is just visible - this is present in all rabbits and not an indicator of disease.



    Liver of second rabbit showing earlier/milder calicivirus symptoms. Yellowing areas and spots have been circled. - Livers pictured above belong to subadult rabbits from same litter and same warren.
    - Light yellow and white areas follow close-up pattern of liver reticulation - this same pattern should appear red against a darker red in a healthy liver.
    - Texture of infected areas of liver is coarse and grainy (healthy livers are smooth, moist and soft). This is because the tissue is dead.
    - Several strains of calicivirus exist, some of which are poorly studied and vary in their lethality and ability to infect non-rabbits. The different viral strains coincide with areas of varying rainfall.
    - Hares do not appear to be infected.
    - Spread by rabbit feces, bedding, hairs, body fluids (eye/nose/urine etc) as well as mosquitoes and fleas.
    - Frequency of infection peaks after rainy seasons due to increase in mosquitoes.
    - Note that wikipedia entry on calicivirus mentions that dry/semi-dry areas have greater incidence of calicivirus than cool/humid areas...however this may be a more complex issue as different strains of calicivirus exist according to local rainfall; and rabbits in cooler areas with more access to water might have better disease resistance due to havign better health and nutrition.
    - Do not eat rabbits with pale regions of the liver or spots.
    - The kidneys will often turn dark brown-red, healthy kidneys should be pale grey-pink.
    - dissection of rabbits that survive calicivirus outbreaks into the next season shows that they have healthy livers - they have genetic resistance and are safe to eat.

    Page with many quality images of calicivirus-infected rabbit livers: http://www.feralscan.org.au/rabbitscan/pagecontent.aspx?page=rabbit_deadrabbits

    Part 4: Taenia tapeworm


    Partially skinned male rabbit with circular tapeworm cyst on inside of left hind leg near scrotum.

    - Circular swellings (cysts) in muscle tissue commonly inside the hind legs or on the backstraps containing clear fluid/jelly. Can be very large and bigger than a fifty cent coin; or go undetected if nestled very close to the spine.
    - White floating specks/ grains in the cyst (just visible through thin layer of muscle in the image above) are immature tapeworms. I will try to get an image of an opened cyst soon.
    - there may be smaller cysts on the intestinal wall but these are normally missed (and easily removed) when the rabbit is gutted.
    - Several species of Taenia exist with the same general life cycle.
    a ) Tapeworm eggs in dog/fox/dingo feces stick to the fur of a passing rabbit and are consumed when the rabbit grooms itself
    b ) Eggs hatch and develop in first larval stage in rabbit intestine, forming intestinal cysts
    c ) Larvae travel through rabbit's body to form second stage in muscle tissue (the cysts you can see)
    d ) Rabbit is eaten by dog/fox/dingo, tapeworm develops to maturity in dog/fox/dingo intestine

    - Transmission to humans is possible from accidental ingestion of dog/fox/dingo feces NOT rabbits, forms cysts in humans. Information: http://dpd.cdc.gov/dpdx/html/Coenurosis.htm Children should be taught not eat random items found on the ground; food and water contaminated with dog feces is a common source of infection in developing countries.

    - Infected rabbits are edible if cyst is removed, cooking will also kill any undetected cysts and immature tapeworms.
    - Does not kill rabbits unless rabbit is weakened beforehand by other medical conditions
    - Emphasis on keeping dogs, cats and ferrets dewormed regularly.
    - Taenia tapeworms are different species from hydatid (Echinococcus) tapeworms, which are a biosecurity risk in Tasmania requiring all incoming dogs from the mainland to be screened. Rabbits do not carry Echinococcus. Echinococcus however creates very similar symptoms in sheep, cattle, wombats, kangaroos and wallabies as Taenia does in rabbits, forming cysts etc.
    - Symptoms and treatment of Taenia tapeworms in humans: http://curezone.com/forums/fm.asp?i=1721955 Australia is not mentioned but the common species here is Taenia multiceps.

    Cyst on upper right front limb of rabbit, ruptured to show contents.



    Removal of a Taenia cyst, I still ate the rest of this rabbit:





    Part 5: Fleas

    The most common flea species on Australian rabbit is Spilopsyllus cuniculi, which was introduced to assist the spread of myxomatosis. However, fleas can spread between different animal species. Spilopsyllus cuniculi can infest the ears of cats, and fleas that normally infest chickens can spread to rabbits.

    They are easiest to spot in the ears and on faces of recently killed rabbits although they are present throughout their fur.

    My personal theory is that the skin is thinnest on the face and ears and there are many fine blood vessels just below the surface. Rabbits would also be more efficient at removing fleas attached to their lower bodies. So large groups of fleas often seem to gather there. The worst I've seen was what at first looked like a large scab of dried blood inside the ear of one rabbit that seemed to cover most of the interior. On close inspection, the 50c coin sized area was nothing but the bodies of hundreds or thousands of fleas all attached to the rabbit and drinking blood at once!

    These are fleas still drinking from the edge of a rabbit's ear immediately after it's death.



    The red specks on the ends of these fleas are their blood-tinged feces.

    Fleas are sensitive to the blood temperature and hormone levels of their hosts. Fleas on a mother rabbit can detect her hormonal changes when she gives birth and will migrate to her offspring. When a rabbit dies, fleas will detect that its body temperature is cooling and jump off over the next hour or so, although most will be gone in a few minutes. This is when they may hitch a ride on hunters or their pets, and bite if they cannot find another rabbit. Bites are small, red, itchy lumps that resemble mosquito bites, some people could be allergic. Calamine lotion will relieve itching.

    Avoid placing entire dead rabbits into containers immediately after death. An example would be tossing shot rabbits immediately into an eski without skinning them. The fleas have nowhere to go except to hop onto whoever reaches into the eski later to retrieve them. To avoid being bitten, either skin rabbits before storing them (fleas will still rather jump away from a human skinning a rabbit than onto them...we are not preferred hosts) or leave the rabbits out long enough to cool and encourage the fleas to drop off. eg. hanging on a fence/back of ute for a while before skinning.

    Affected rabbits scratch and groom themselves frequently, and extreme infestations can cause anaemia. In pet rabbits, gritty specks of dry flea feces may be seen in the fur. Flea powders, baths and collars are available for pets, however, flea collars are highly TOXIC to pet rabbits.

    Surges in flea populations can indicate a coming myxomatosis outbreak in wild rabbits.

    Part 6: Bacterial cysts



    More info pending. Very large, irregular cyst in abdomen of male rabbit. Intestines have been removed in this picture. Interior fluid is pressurised and clear/translucent and lacks the white 'grains' seen in tapeworm cysts pictured earlier.

    - info pending
    - possibly zoonotic?

    Part 7. External injuries and abscesses

    Injuries from accidents, predators and fights between rabbits can sometimes be felt as rough, dry scabs or patches under the fur that may also contain pus. The below image is of a rabbit with several dry (no pus) recent injuries. I had to part the fur to make them visible. These become more common in crowded warrens where rabbits may be fighting for space. These injuries were very superficial, did not extend below the skin and the muscle tissue underneath was healthy. Carcass was acceptable to eat but I would recommend avoiding animals with deep, infected or gangrenous wounds.



    - more info pending

  • #2
    Good read Burp.

    Thanks...

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    • Guest's Avatar
      Guest commented
      Editing a comment
      Thanks Mav. I've added new info and pics now too.

  • #3
    this is awesome info thanks for taking the time to share this

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    • sirus17
      sirus17 commented
      Editing a comment
      Grate information, the last one looks abit like ringworm haha

  • #4
    Thanks Burp - This is good info.
    Hunkachunka

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    • Greenwich-biker
      Greenwich-biker commented
      Editing a comment
      Awesome post Burp, I'm glad you took the trouble to bring it over

  • #5
    Make have you come across and Pindone poisoned rabbits in your travels? There are a couple of places out here that use it, Considering what I've cut and pasted below, if you grabbed a bunny early after it eating a bait it might not show. Of course there does have to be signs up as part of the licensing to use it.

    Pindone is an anticoagulant that kills by interfering with blood clotting, causing fatal haemorrhages. It takes around 10 to 14 days for rabbits to die following initial ingestion of pindone. During that time the animals bleed from the nose, mouth, eyes and anus, and pain from bleeding in internal organs, muscles and joints lasts for several days before they die. It has it's critic's in that owls can be poisoned by eating pindone-contaminated carcasses and that "raptors appear to share the high sensitivity [to pindone] of rabbits, based on results for wedge-tailed eagles and brown goshawks".

    an elderly Aboriginal woman out here was telling me that if something they are going to eat is a little suspect they put a bit out for black ants to eat, if they leave it they then won't eat it and it has to be BLACK ANTS because other types are not affected and will eat anything.

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    • Guest's Avatar
      Guest commented
      Editing a comment
      Originally posted by Uncle" post=19756
      Make have you come across and Pindone poisoned rabbits in your travels? There are a couple of places out here that use it,
      None so far, and thanks for the info. The landowners here have only used burrow ripping, fumigation and shooting. If you get a rabbit that has been poisoned, could you post a photo for everyone to have a look at?
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