Bacteria, Viruses and Parasites

Coccidia

Coccidia is a species of protozoa organisms.
These are parasites of epithelial cells, which are the cells that recover surfaces, like skin, or in this specific case, GI tissues.
Of the 12 species of Coccidia associated with rabbits, it is not abnormal to find that one single rabbit has two or more species at the same time.
Different species of Coccidia affect different body parts.

Rabbits have to common ways of getting infected:
1. By eating: wild fresh plants like grass can contain the Oocytes (eggs) of coccidian species.

2. By other rabbits: Oocytes activate after around two days have passed, and can live for about a year if met with the right conditions like damp environments. The faeces (which are normally laid by the urine) meet those requirements. These faeces can be ingested or, by just the touch with food and water, release the oocytes, which are later on ingested by other rabbits.

Coccidia normally presents itself in the rabbit droppings, thus it can be diagnosed with these, the issue is that it is commonly unimportant to do so, as rabbits with Coccidia are normally asymptomatic.
That does not mean that rabbits can’t get affected by it.

Coccidian infections inhibit or hypertrophy the cells they infect, leading to nutrient malabsorption, anaemia, hypoprotenemia, and dehydration, amongst other things.
An intestinal coccidiosis can develop general sickness symptoms like lack of appetite and depression, and also includes weight loss, abdominal pain and sometimes diarrhoea. This makes the mucous membranes pale and watery.
These membranes can be seen alongside blood in the faeces.

Sadly, intestinal coccidiosis is only diagnosed post mortem, which slowly occurs if weight loss reaches 20% of the body mass, which causes convulsions and/or paralysis.
Intestinal coccidiosis mainly affects rabbits from 6 weeks to 5 months old, and is attributed to stress and/or immunosuppression.

Young rabbits can be very susceptible to Coccidian species. Eimeria stiedai is one of them, which causes damage by obstructing the bile ducts and causing fibrosis in the liver (the liver tissue gets tick or scarred) leading into hepatic damage. This leads to diarrhoea, weight loss, jaundice (due to the liver damage), ascites (liquid retention in the abdomen), and slowed growth.


The worst news is that treatment is life-long and it is not definitive. Coccidiosis has been seen to relapse after a week or two, and only rabbits that were infected recently have a chance of recovery. Treatment does not guarantee that the rabbit will not succumb to the disease, and Coccidia can slowly become resistant of the preventive medicine that can be given to rabbits.


If you want to learn more about Coccidia and coccidiosis you can see:
The Unusual Pet Vets’ PDF about Coccidia.
MediRabbit’s extensive information sheet on Protozoal enteritis caused by Coccidiosis.

Coccidia oocysts - Leclaire, S., Faulkner, C. T., 2014.

A B
Cystoisospora species.

C
Coccidia oocyst with multiple sporocysts.

D
large brown coccidia.

E
Eimeria oocyst.

Lucilia eximia - Ecos del Bosque.
Calliphoridae larva - BugGuide.

Flystrike (Myiasis)

Myiasis is the infection of fly larvae in tissue.
Although it rarely happens to humans, it can occur to rabbits with certain issues.
It is of very important matter, and rabbits with larvae must be taken to the vet immediately.


Every fly is capable of causing flystrike, but the Calliphoridae family is notable as some of these don’t require an open wound to cause the infection, and because they can use other flies to carry their eggs for them. These are known to infect from cattle to house pets.

It occurs when flies are attracted to a certain thing, such as a smell (from urine or faeces) or open wound, and decide to lay their eggs there.
These hatch into larvae that start feeding on the flesh of the infected animal, which causes more flies to be attracted.
The wounds can become infected, and tissue can be permanently damaged.

It is also documented that Lucilia cuprina’s maggots, also from the Calliphoridae family (bowflies), mainly affecting sheep, generate ammonia from eating tissue which intoxicates the host.

Preventive action includes ensuring the rabbit and their areas are clean, this may be due to an incapability of cleaning themselves (Obesity, Arthritis), or to sickness (Diarrhoea, Urinary issues).
It is also important to keep any open wound clean and dry.

To learn more about flystrike in rabbits, you can visit:
Rabbit Welfare Association and Fund’s information about flystrike.
Bunny Lady’s article about flystrike and how to prevent it.

To learn more about flystrike in general, or the Calliphoridae family, you can see:
Wikipedia’s article about myiasis (contains harsh images).
Wikipedia’s article about the Calliphoridae family.
Wikipedia’s article about Lucilia cuprina or the Australian sheep bowfly.

E. Cuniculi and Headtilt

Encephalitozoon Cuniculi and headtilt come hand in hand, although E. Cuniculi is not the only cause for headtilt.

Headtilt occurs when the inner ear of the rabbit gets infected and/or damaged (Peripheral) or when a pathogen enters the part of the brain that connects with the ear (Central).
In both cases, the rabbit loses balance and their eyes are damaged, thus they turn their head to correct the position the brain thinks it is in.
Damage on the inner ear may occur due to many things, such as bacterial infections that expanded from the respiratory tract, or due to trauma.
Neurological damage can be caused by bacterial infections or by E. Cuniculi, but other symptoms are developed before headtilt, such as erratic movement, seizures, paralysis, or lack of appetite amongst others.
Bacterial headtilt can be reversible depending of the stage of infection, but headtilt due to trauma or parasitic infection are not completely reversible, although it has been observed that the heads do straighten a bit after parasitic infections are cured.

Strokes due to E. Cuniculi are easily recognisable, as the rabbit completely loses control and starts spinning on itself.


E. Cuniculi is known as a spore-forming parasitic fungus, where Encephalito- from encephalitis, means inflammation of the brain, and -zoon from zooid, means organism, and where cuniculi is the plural of cuniculus, meaning small conduits, indicating the way this pathogen reproduces.
E.C. can be also found in the rabbit’s kidneys, and can cause kidney failure.

The scariest part of E. Cuniculi is that a rabbit could carry the parasite but never have symptoms, but these can be randomly triggered or transferred to another healthy rabbit, thus starting the process.
E.C. is treatable, but damage in the ear or the brain could leave the rabbit with headtilt for the rest of their lives.
If caught early, the rabbit can recover from the symptoms, including headtilt.

You can learn more about E. Cuniculi and headtilt from our sources below:
Wikipedia’s entry on E. Cuniculi.
Rabbit Welfare Association and Fund’s information sheet about E. Cuniculi.
The Educated Rabbit’s extensive information sheet about headtilt and its causes.

E. Cuniculi life cycle - Carly N. Jordan 2005.
Rabbit with mild headtilt - The Educated Rabbit.
Myxoma virus - MicrobeWiki.
Rabbits with Myxomatosis symptoms - Salem H.M., Morsy E.A., Hassanen E.I., Shehata A.A.

A
Swollen upper eyelid with edema.

B
Conjuntivitis with lacrimation.

C
Pseudotumour with crust emerging from a Myxoma on the upper lips.

Myxomatosis

Myxomatosis is a viral disease only affecting Lagomorphs.
Its origins place the virus in South America and North America, where the local population only shows symptoms as skin nodules.
In European rabbits though, the disease is fatal.

The Californian and Mexican strain is the most virulent, whilst the South and Central American one is slightly less potent.
The current European and Australian strain is the less fatal.

The disease is also known to infect hares and pikas alike.

The main way of transmission is through insect bites, especially fleas and mosquitoes that have already fed from a sick rabbit.
A secondary transmission route are body secretions, like snot from the nose or secretions from the reproductory organs.
This makes all rabbits, regardless of where they live, prone to get infected.

House rabbits are less likely to get sick, as outdoor rabbits tend to be in contact with ground that could’ve been visited by wild rabbits, thus preventing the entry of outside animals and ensuring the grounds are safe should reduce the likelihood of your rabbits contracting Myxomatosis.
Another very important way of protecting your rabbits is by vaccinations. Vaccination does not guarantee that the rabbit will not contract the disease, but it greatly improves the chance of survival.
To ensure they survive, a rabbit vet will treat the rabbit accordingly based on its symptoms.

The Blue Cross gives some symptoms of myxomatosis, and Wikipedia provides a time table.
These symptoms, that show within 5 to 14 days are:
Swelling, redness and/or ulcers. Especially around the place of infection.

Facial discharge. Eye discharge is of a white colour, the nasal discharge is mucopurulent, meaning that it is not only mucous but also includes pus. In other strains, this discharge can be clear.

Blindness due to inflammation of the eyes.

Respiratory issues showing as dyspnoea due to the nasal discharge. That if left untreated after the rabbit survives can develop into pneumonia.

Other general sickness symptoms of rabbit disease like depression, lethargy, loss of appetite, etc…

If you want to learn more about myxomatosis you can read:
The Rabbit Welfare Association and Fund’s brief on Rabbits and Myxomatosis.
The Blue Cross’ information sheet about What is Myxomatosis.
Wikipedia’s article in Myxomatosis.

Parasites

Rabbits, alike many other animals, are prone to be infected by parasites, whether these are in or outside of their body.

We have already talked about some of them, like Coccidia, E. Cuniculi, and Flystrike, three horrible infections with a variety of symptoms.
Now we must learn about other less lethal, but still harmful, parasites.

Skin parasites (ectoparasites) include what you could find in other pets:
Mites like Cheyletiella affect dogs, cats, and rabbits, and big infections are usually caused because the rabbit is immunocompromised, so it’s a good idea to check for any underlying issue.
There are also mites that are specialised to live inside the ears, but these are harder to diagnose because bacterial and fungal issues may develop similar symptoms, thus it is recommended for a vet to check under a microscope.

Ticks and fleas also affect rabbits.
Fleas can be dealt with by thoroughly cleaning the environment and applying the necessary pest control, of course this must be done after removing the rabbit, who also has to be cleansed. Those fleas specialised in rabbits target the ears.
Ticks can also be an issue, and big tick infestations can easily and quickly debilitate rabbits.

Soap has had a tick once that latched into his eyelid. Thankfully, it was short lived, as it quickly fell and was stepped on by someone!

Myiasis can occur when a fly deposits its eggs in the rabbit flesh, the larvae hatch and start feeding on the rabbit. This is also considered a parasitic infection.
Mosquitoes can also be an issue, especially because these are difficult to control and can transmit RVHD faster than any of the above.

There are other parasites that affect rabbits from within:
E. Cuniculi is one of them, infecting the brain and other organs and causing a plethora of issues like paralysis, seizures, and headtilt.
Baylisascaris is a roundworm found in raccoons that can infect the eyes and the brains alongside the rest of the organs and has similar symptoms to E. Cuniculi.
Coccidia are parasites infecting the GI tract, they affect the lining of the intestines, causing weight loss and diarrhoea among other things. There is also a second type of Coccidia that infects the liver causing hepatic damage.

Rabbits are also prone to pinworms, tapeworms, and other round worms.

Vets are able to give you anti-parasite drops or sprays that allow for protection and diagnosis. If you buy these from a pet shop please remember: Most of these sprays made for dogs and cats are toxic for rabbits.

In case of parasitic infection, other preparation and care must be made with the veterinary expert.

If you want to learn more about parasites you can read:
The Rabbit Welfare Association and Fund’s page on Skin and Fur Parasites.
Exotic Pet Vet’s information sheet about Parasites of Rabbits.

Ear Mites - The Rabbit Welfare Association and Fund.
Soap with a tick by his eye.
Post-Mortem examination of a rabbit with RHDV - Velarde, R., Cavadini, P., et al., 2017.

A
Post-mortem side view.

B
Bleeding from the nose.

C
Liver necrosis.

D
Close-up of a liver lobe.

(More detailed information in the source)

RHDV (Rabbit Haemorrhagic Disease) 1 & 2

Rabbit Viral Haemorrhagic Disease or RHDV are two strains of viral hepatitis only affecting rabbits, with a mortality of 70-100%.
Some strains also affect hares and cottontails.

Infection symptoms include liver necrosis and coagulation in most blood vessels, worsening the necrosis and reducing the blood supply to other organs. Blocked vessels may rupture due to the pressure, creating internal and external bleeding from orifices.

The issue with RHDV strains is that, due to how most symptoms are internal, there are no clear signs of disease, to the point where some rabbits are thought to die of something else but the virus, making so the only way of diagnosis is post-mortem.
This is called a peracute case.

In acute cases bunnies show general sickness symptoms alongside high fevers, bloody discharge from orifices and in poop and urine. Lethargy, coma and convulsions are common before death, and rabbits with these symptoms die within 12 to 36 hours after developing the fever.

Chronicity is commonly a symptom of RHDV2 and symptoms include general sickness symptoms, anorexia, and jaundice (yellowing of the eyes and other tissues) due to high levels of bilirubin. GI dilation, arrhythmia, heart murmurs and neurological issues may occur. Death comes within 1 to 2 weeks and is due to liver failure.

Rabbits can also be asymptomatic, and due to the incubation period, especially of RHDV2 (3-5 days), the rabbit can infect other rabbits without prior notice.
The good news is that there are vaccines, and that these are very effective at controlling infections, thus it is very recommended for you to vaccinate your rabbits accordingly for both strains of RHDV.

If you want to learn more about RHDV, you can read:
The Rabbit Welfare Association and Fund’s information sheet about RHDV.
Wikipedia’s article on Rabbit Haemorrhagic Disease.

Snuffles

Snuffles is the generation of mucous in nose and eyes due to a bacterial infection within the sinuses and tear ducts.
This mucus may also be accompanied by sneezing and wheezing, which means the infection has reached the later stages.

It is not uncommon to see general sickness symptoms alongside drooling (due to mouth-breathing), and dirty, matted paws, as they try to clean the mucous from their face.
Skin sores may also develop due to the constant wiping and liquid within the nose and eyes areas.

Rabbits with dental diseases are prone to developing snuffles due to how close the tooth roots are to the tear ducts. Malocclusion can also create issues as the deformity causes the ducts to close, creating a special environment for bacteria to grow.

If the infection reaches the ears, it may cause reversible headtilt. Reversible meaning that partial or complete tilt may be cured. Regardless, in very advanced infections where headtilt is severe, it may become hard to reverse the tilt.

In mild cases, the symptoms can be easily controlled and the rabbit can heal. In grave cases, rabbits can develop pneumonia, which greatly increases mortality.

Sadly, these infections are hard to eradicate, and can only be prevented with proper care and controlled with medication, thus it is not uncommon to find that a rabbit that has previously been infected has developed snuffles again.

Ensuring your rabbit isn’t stressed and has a healthy immune system is a great way of reducing the chance infection and reducing relapses.

The bacteria commonly causing infection are Pasteurella spp. and Staphylococcus spp., but other bacteria like Bordatella Bronchiseptica (also affecting humans and dogs) and Pseudomonas can also infect your rabbits.

If you want to learn more about snuffles, you can always visit:
The Rabbit Lady’s page on Snuffles in Rabbits.
Bishops Stortford Veterinary Hospital’s facts list on Snuffles.
The Rabbit Welfare Association and Fund’s information sheet about Rabbit Snuffles.

Runny eyes - The Rabbit Welfare Association and Fund.
Runny nose - The Rabbit Welfare Association and Fund.
White focci on the ceacum's appendage - MediRabbit.

Yersiniosis

Also called pseudotuberculosis, yersiniosis is a rare disease that usually affects adult animals.
The visible symptoms show as the rabbit eats less to the point of stopping, which drops their weight rapidly. Death follows soon after.
Droppings become hard and sticky, and their size decreases as food intake decreases.
When palpating, the belly is soft and you may be able to feel the content of the abdominal cavity decrease.

Birds and rodents normally carry the disease, these may include guinea pigs, so rabbits cohabitating with these animals can become infected. This is why cleanliness is key for prevention.
Wild rabbits can also become infected.

Hares are very sensitive and yersiniosis tends to be a common cause of death in some countries.

The bacteria can be found in both sick and healthy individuals as well as the general environment if in contact with faeces of an infected individual.
With a survival span of a year, the bacteria can reproduce at ranges of 4º C to 10ºC, which may explain the infection rates of rabbits in winter.

With high zoonosis, especially to children and immunosuppressed patients, it causes symptoms similar to appendicitis.
Both animals and humans can be affected by generalised infections, severe septicemia or localised infections in lungs or eyes.

The rabbit may show symptoms after the approximate 15 day incubation period.
Septicemic infections kill within 24 to 48 hours, whilst chronic forms could kill after 2 to 3 months, although these latter are commonly survivable.
The bacteria reaches the intestine and multiplies, thereafter it infects the lymphatic nodules.
Once the previous stage is reached, the liver is affected, which begins the septicemia.

With the other forms, the rabbit may show general sickness symptoms including exhaustion. Diarrhoea may also develop.
Yersiniosis can also target kidneys and lungs.

During palpation, you may be able to feel the hypertrophied
(large in size, sometimes swollen and hard) lymphatic nodules. The liver will have hard nodules too.
Whilst palpating you may find that the spleen may have grown in size (up to three times).

If there is exploratory surgery, white or yellow nodules (spots) may be seen in the ceacum, kidneys, and spleen, the intestine can present necrotic regions.
A diagnosis can be obtained by doing a biopsy of the affected organs.

If you want to learn more about yersiniosis you can visit (Careful, strong images):
Medirabbit’s page on rabbit tuberculosis.
Frances Harcourt-Brown’s image of the white/yellow nodules in the organs.

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