Conclusion Caturday: Gaunt Gagging Goats (Case 4)

Photo of TA Douglas (Left) and Professor Pocky (Right) taken by Dr. Haus

 

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Quick Review

Diagnosis:

🪱PARASITIC INFECTION:  DICTYOCAULUS FILARIA🪱

 

Pathophysiological Point:

Dictyocaulus filaria (D. filaria) is a parasitic infection.  The D. filaria larvae are ingested by the goat and penetrate through the small intestines into the blood stream.  The larvae arrive at the lungs where they develop into adult lung worms.  As the larvae develop, they block bronchioles and lead to eosinophils, lymphocytes, and plasma cells entering the bronchioles causing an inflammatory state.  Some larvae/eggs fall into the alveoli leading to inflammation in the alveoli.  The eggs/larvae are coughed up, swallowed, pooped out, and the cycle continues.

 

 Questions, Answers, and Further Information:

 

Level 1 Questions, Answers, and Further Information:

1. Explain what the lungs do and why they are important.
   
   The lungs are what allows the body to breathe.  Breathing is important because it brings oxygen into the body and gets rid of the carbon dioxide.
   
   
2. Why do you think the goats are having trouble breathing?  (HINT:  Think about the effect a parasite in the lungs would have on breathing)
   
   The goats are having trouble breathing because the parasite is blocking the lungs and not letting the air flow smoothly into and out of the lungs.  The inflammation in the lungs is also making it harder to move air into and out of the lungs.
   
   
3. Challenge question, why do you think the goats are losing weight?  (HINT:  There are multiple answers to this question.  Think about what parasites do to the body and how a parasite that makes it hard to breathe would affect the goats)
   
   There are two major answers to this question.  The first answer is that parasites steal the nutrients from a host so the goats are losing weight because the parasites are stealing the goats nutrients.  Also, since the goats need to work so hard to breathe they are not able to eat very much or for very long.  Next time you eat, try to breathe heavily and eat - it is hard to do!
   
   

   Helpful Links:

   • Penn State Extension Prevent Parasites Through Grazing Management:  https://extension.psu.edu/prevent-parasites-through-grazing-management
     
     
   • University of Arkansas Extension Parasites in Small Ruminants:     https://www.uaex.uada.edu/farm-ranch/animals-forages/sheep-goats/internal-parasite-control.aspx
     

 

Level 2 Questions, Answers, and Further Information:

1. Explain how inflammation in the alveoli affects the exchange of oxygen and carbon dioxide in the body.  Why does this lead to an increased respiratory rate in the goats?
   
   Inflammation leads to an increase of blood flow to an area of injury and increased leakiness of the blood vessels around an injury.  Due to this, the area begins to swell.  When is happens, the distance between the inside of the alveoli and the blood stream becomes greater.  This makes it harder for gases like oxygen and carbon dioxide to diffuse between the two spaces.  This inflammation also narrows the bronchi, bronchioles, etc. leading to less air getting to the alveoli.  
   
   The goats body will sense the lower oxygen concentrations and higher carbon dioxide concentrations in the bloodstream which will active homeostatic mechanisms to increase breathing rate to try to bring in more oxygen and release more carbon dioxide.
   
   
2. How will this disease affect the compliance of the affected goats' lungs later in life?  (HINT:  Compliance is how well the lungs can expand to accommodate air.  Think about how the body heals injuries and how this might affect lung compliance)
   
   These goats will likely develop scar tissue in their lungs in locations where the parasites inflicted extensive damage.  Tissues that heal with scar tissue do not act as the "normal" tissue in that area will act.  In these areas of scar tissue, the body will not be able to exchange oxygen and carbon dioxide.  This will decrease the compliance of the lungs as they will not be able to stretch as much as normal lung tissue.
   
   
3. Challenge question, explain the pulmonary mechanism that allows the parasite to spread between hosts in the fecal-oral route.  In other words, what mechanism allows the eggs produced by the adult lung worms to enter the gastrointestinal tract?
   
   The mucociliary apparatus (escalator) (MCA) is used by this parasite for its life cycle.  The MCA functions to capture foreign material from the lungs in mucus to be coughed up and swallowed.  This is exactly how the parasitic eggs will be able to be pooped back out into the environment to be picked up by a new host.  This will continue the spread of the parasite between animals.
   
   

   Helpful Links:
   

   • Merck Vet Manual Lungworm in Animals:                            https://www.merckvetmanual.com/respiratory-system/lungworm-infection/lungworm-infection-in-animals
     
     
   • Sorting Through the Information on Sheep and Goat Parasite Control: A Decision Making Support Tool:  https://extension.vet.osu.edu/beef-sheep-resources/sheep-and-goat-parasite-control-decision-making-support-tool
     
     
     

Level 3 Questions, Answers, and Further Information:

1. Describe the treatment plan you would recommend for the goats and why you are recommending each part of your treatment plan.  Please answer this question as if you are speaking to a professional colleague.
   
   Given the clinical signs in the affected goats, they should be started on a deworming medication that targets the D. filaria.  This farm should begin to implement rotational grazing on their property and avoid putting young animals on pastures that have been inhabited for a long time by the older goats to decrease parasitic load.  The farm protocols and management should be reviewed to determine what other changes need to be made to decrease parasite load.  There is work being done to create a vaccination against D. filaria (the more you know).
   
   
2. Describe your recommended treatment plan and why you are recommending each part of your treatment plan.  Please answer this question as if you are explaining it to a client/patient without a scientific background.
   
   Today we found lung parasites in your goats.  This means we need to treat the affected goats with a medication that kills the parasites.  Let's go over our farm protocols to see if there are other ways we can decrease the changes that your goats will be exposed to parasites.
   
   
3. How does this disease affect these goat's V/Q ratio (ventilation/perfusion ratio)?
   
   This disease will affect the patient's ventilation and thus create a shunt.
   
   

   Helpful Links:

   
   
   • Physiology, Pulmonary Ventilation and Perfusion:                        https://www.ncbi.nlm.nih.gov/books/NBK539907/
     
     
   • Prevalence and Risk Factors of Bovine and Ovine Lungworm Infection at Durame District, Southern Ethiopia:                                                                          https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8660247/
     
   
   

Day 3 Conclusion

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