Laboratory 4




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    Oslerus (Filaroides) osleri

      PATIENT: 1 1/2 year old male schnauzer.

      HISTORY: During the last 2-3 weeks there was periodic respiratory distress, the dog would have labored breathing, become cyanotic, and pass out. Taken to 3 different veterinarians who diagnosed:

      1) allergy 2) pneumonia 3) normal dog.

      PHYSICAL EXAMINATION: Dog sits on front elbows abducted, "gasping for breath". During attacks the dog became cyanotic. Decreased lung sounds on the right side.

      TENTATIVE DIAGNOSIS: 1) Diaphragmatic hernia, 2) Tension pneumothorax, 3) Allergy.


      • 1. Hospitalized for 8 days (10/24 to 11/2), radiographs indicated a pneumothorax, given antibiotics and had air removed from thorax periodically. A thoracotomy (10/27) showed nothing abnormal. Dog sent home 1/2.
      • 2. Returned 11/5 for removal of more air from thorax. Radiographs indicated air in the mediastinum (possibly leaking from trachea).
      • 3. Readmitted 11/10. Radiographs indicated a spherical density of the ventral aspect of the trachea at the level of the right cardiac border. A blood smear showed many microfilariae*. Broncoscopy showed numerous nodular growths (1 to 5 mm) from the mid-trachea into both main stem bronchi. Several were large enough to obstruct bronchi during deep inspiration. Removed enough to make a patent opening. (Several nodules sent to pathology). Pathology indicated granulomas containing numerous nematodes. Dog was sent home.
      • 4. Re-examined 11/23: Breathing normally. removed several nodules from trachea.
      • 5. Re-examined 12/17: Dog normal.

      DIAGNOSIS: Pneumothorax due to leakage of air from the trachea. Wall of trachea weakened due to Oslerus osleri infection.

      NOTE: At the time this dog was seen there were no anthelmintics which were active against O. osleri. Today we have several effective drugs to kill this worm and one of them would have been used in this dog along with the surgery.

      *This indicated that the dog had heartworm in addition to the Oslerus osleri infection.



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    Filaroides oserli Radiographs:

    Two left lateral recumbent chest radiographs; BEFORE (11/5/70) and AFTER (1/25/71) treatment.



    BEFORE Treatment:

    There is air within the cranial mediastinum (pneumomediastinum) and also air in the pleural space (pneumothorax). Note the patchy radiolucencies ventral to the trachea at the thoracic inlet and the ability to see both the inner and outer wall of the trachea (i.e. pneumomediastinum). Note also that the aorta is clearly delineated because of the air in the pleural space (compare these areas with the AFTER Treatment radiograph). The outline of a partially collapsed caudal lung lobe can be recognized as it is partially superimposed on the base of the heart and extening dorsally and caudally. There is a nodule seen in the distal trachea protruding from the ventral mucosal surface into the lumen that is seen because of the air outlining its edge. Another nodule is probably present at the carina (tracheal bifurcation) because of the circular opacity noted superimposed on the ribs at this location. This nodule could be obstructing the caudal lobe bronchus and contributing to the collapsed lung lobe. Additional radiographic views, such as the right lateral recumbent or ventro-dorsal, would assist in confirmation of the nodule at the carina and identification of possible additional nodules. An endoscopic examination of the trachea would provide direct visualization of the tracheal nodules.



    AFTER Treatment:

    The pneumomediastinum and pneumothorax have resolved. The tracheal nodule previously seen in the caudal ventral trachea is not evident, but there may be a residual nodule in the region of the carina.


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    Caval Syndrome Ultrasound



Ultrasound showing caval syndrome. Numerous white spots can be seen in the uppermost section. These spots represent adult worms in the right ventricle


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      Review Question

      The larva under the microscope was recovered using a Baermann apparatus from the feces of a 4 month old puppy which has had chronic diarrhea.

      A. Identify the nematode (Genus and species).

      B. Is this parasite zoonotic?

      Click here for the answer

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