It seems that we are seeing an influx of posts concerning upper respiratory infections in snakes that, even though cultured, do not respond to multiple rounds of antibiotics.
Upper respiratory infections in snakes can be caused by bacterial, viral, parasitic and fungal infections.
I have to admit that in many years of keeping snakes, I have not had a case of a bacterial or parasitic URI in a long term captive animal – only in imports. But I have also seen and treated parasitic and fungal causes to the infections.
Depending on the skill and experience of the vet treating your animal, a culture (usually via tracheal wash) can either be enlightening or confusing. Many cases of bacterial URI are caused by an overgrowth of naturally occurring bacteria due to a suppressed immune system as the result of another ailment. The URI is treated, responds and then re-occurs because the underlying causative agent has not been diagnosed.
The result of a bacterial culture will show, usually in decreasing order, the antibiotics that the suspected causative bacterium is most susceptible to.
Therefore, if multiple rounds of antibiotic treatment prove ineffective, and if the infection is spreading rapidly through your collection, it may be time to consider that something else may be causing the URI.
Viruses and URI
Viruses that may show URIs as primary or secondary symptoms are varied and harder to detect. Often, they are secondary symptoms to a less noticeable primary symptom. OPMV is an example of a viral infection that can initially present with respiratory symptoms. Our vet recently told me that she is seeing quite a bit of OPMV – in fact she sees more of it than IBD.
When I worked in Australia, several of my co-workers dealt with parvovirus outbreaks in their captive snake collections. While the main symptoms were gastrointestinal, these symptoms were acute and the first signs of distress ended up being respiratory in nature.
One of my foremen in Perth had a large aspidites and antaresia collection that was devastated by a picornavirus outbreak. Picornaviruses include rhinoviruses which are mainly respiratory in nature. I do not recall how the virus was isolated, but I do remember that it spread rapidly through his collection and that he spent a small fortune in antibiotic treatments that had no effect.
Parasites and URIs
Cryptosporidiosis (Crypto) is an example of a parasitic infection that, while mainly gastric in nature, can manifest itself in the early stages as pneumonia. As the disease progresses, regurges and anorexia are more common.
About 8 years ago, I received a WC yellow tail cribo from an importer than was infected with crypto. A fecal was performed which showed the normal imported South American bugs but nothing else. For three months the snake ate fine but had an incurable URI. Our vet would treat him, his symptoms would go away for a week or two and then return. At about 9 months, he began regurging and refusing to eat.
I kept him in quarantine, which most likely kept the parasite from spreading to the rest of my animals. At the first signs of gastric distress, the vet performed another fecal which showed crypto. A snake with crypto does not consistently shed the parasite upon defecation, therefore one clear fecal does not necessarily mean the animal does not have crypto. Unfortunately this animal needed to be euthanized.
I ended up throwing away the cage, water bowls and husbandry tools associated with this snake. The building I used for QT (large furnished shed) was vacated and sprayed with ammonia. I did not use it again for almost 8 months. My vet joked that I needed to burn it to the ground and then sow the site with salt. The rest of my collection was locked down and I did not breed any animals that season. I also began taking in fecal samples for random testing of all my snakes. It never reared its head again.
There are other parasites that live in the lung of a snake such as lung mites, pentastomids and lungworms. . These usually are diagnosed via bronchoscopy.
Keeping your snake in a poorly ventilated but humid environment can result in myco-fungi outbreaks which can damage the lung tissue.
Two years ago, the entire Skiploder family took a two week vacation to Montana and Idaho. Our pet sitter got a little carried away in spritzing the spilotes cages, resulting in a fungal lung infection of one of the females. When we came back there was mold growing in her cage which I noted and took a sample in to the vet. The causative fungus was aspergillis and it was treated with flucanozole.
Bacterial Infections as Secondary
Oftentimes, snakes can have an underlying primary health issue – be it viral, systemic, parasitic or even environmental that goes unnoticed or uncorrected. In these instances, this primary issue results in a secondary bacterial infection caused by the suppression of the immune system.
I always suspect that in many of the cases where a bacterial URI responds favorably to antibiotic treatment and then a month or two later recurs; that there is either a husbandry related issue or a systemic problem (renal, gastro-intestinal, parasitic, etc.) that is not throwing any symptoms but is weakening the animal.
I am not a vet and I do not intend for any advice that I give to substituted for the direction of a qualified herp vet. However, there are a lot of hack vets out there that do not perform cultures and throw antibiotics at every URI case they see. When repeated treatments do not help, it is time to consider the myriad of other possible health issues that may be affecting your animal. Please use this post only to assist you in asking your vet questions that make you feel comfortable with the course of treatment he/she is prescribing.