Respiratory issues in a kitten

SIGNALMENT AND HISTORY

A four–month-old, female, domestic shorthair kitten was referred with chronic respiratory signs including severe dyspnea. Suspected pneumonia was previously treated with antibiotics and anthelmintics without clinical improvement. Serological FIV/FeLV test was negative.

 

PHYSICAL EXAMINATION

Physical examination revealed severe respiratory distress and poor body condition.

 

INVESTIGATION 

Haematology and biochemistry

Only a mild non-regenerative anemia was detected. Results were, otherwise, unremarkable.

Imagin diagnostic 

Thoracic radiographies showed a generalized alveolar pattern with bilateral pulmonary consolidation consistent with bronchopneumonia (Figure 1).

Figure 1. Latero-lateral X-ray showing a generalized alveolar pattern

Cytology

Cytological samples from a consolidated lung lobe were taken (Figures 2 and 3). Bronchoalveolar lavage was not done due to the poor patient condition and the high anesthetic risk.

Figure 2. Microgaph from consolidated lung lobe cytology. Granulomatous inflammation with several macrophages and giant multinucleated cells. Modified-Wright stain.
Figure 3. Micrograph from consolidated lung lobe cytology. Granulomatous inflammation and presence of parasitic ova and larvae.

Questions:

1.       What is your cytological diagnosis?

2.       What is the most likely diagnosis?

3.       Which further tests would you perform to better identify the infectious agent?

1.       1. What is your cytological diagnosis?

On cytology, marked macrophagic inflammation associated with nematode infection (metastrongyloid bronchopneumonia) and epithelial dysplasia were diagnosed. Larvae length was approximately 10x350 mm with occasionally morulae eggs of 150x300 mm size.

 

2.       2. What is the most likely diagnosis?

Metastrongyloid bronchopneumonia

 

3.       3. Which further tests would you perform to better identify the infectious agent?

Complete fecal examination including flotation, sedimentation and Baermann methods to identify first stage (L1) larvae.

 

FOLLOW-UP

 

Despite hospitalization, the kitten died few hours after admission because of severe respiratory condition. 

Zinc sulphate flotation and Baermann technique were performed to identify first stage (L1) larvae. An infection with Aelurostrongylus abstrusus and/or Troglostrongylus sp. was confirmed by fecal examination

DIAGNOSIS: Parasitic granulomatous pneumonia due to A. abstrusus and/or Troglostrongylus sp. infection

On post-mortem examination, approximately 90% of the evaluated lung was affected. Several parasite eggs were found on alveolar lumen. Adult and larvae stages were observed in bronchiolar lumen associated with an intense inflammatory granulomatous infiltrate. Larvae forms were also found in colonic lumen and crypts (Figure 4).

Figure 4. Microgaph from consolidated lung lobe section. Presence of parasitic forms accompanied by granulomatous inflammation. H&E staining.

SUMMARY

The diagnosis of parasitic bronchopneumonia can be challenging due to a wide spectrum of clinical manifestations from subclinical infections to non-specific clinical signs. Severe lungworm disease is most often observed in young, debilitated and/or immunosuppressed animals leading sometimes to death. The best diagnostic method in these cases is the coprological examination. When lung consolidation is present, fine needle aspiration (FNA) of the lung is recommended.

Lung FNA cytology is less invasive diagnostic method than BAL, it can be performed without anesthesia, but it may have a small risk of pneumothorax. On the other hand, is a useful technique for the identification of metastrongyloids parasites in the absence of fecal samples or a negative coprological examination. Furthermore, inflammatory response is evaluated on cytological specimens.

Early infection with A. abstrusus is characterized by the presence of eosinophils and neutrophils in BAL samples. The meaning of the predominance of macrophages in this case remains unknown but, classically, macrophagic inflammation is associated with chronic disease while eosinophilic is commonly seen in early stage of lungworm disease.

Morphological discrimination between A. abstrusus and Troglostrongylus spp. is complicated because of similarities of their L1 larvae. Therefore, molecular analysis should be applied to discriminate between these infections.

 

References:

Annoscia G, Latrofa MS, Campbell BE, et al.: Simultaneous detection of the feline lungworms Troglostrongylus brevior and Aelurostrongylus abstrusus by anewly developed duplex-PCR. Vet. Parasitol 2014; 199:172-178

 

Burkhard MJ and Millward LM: Respiratory Tract. In Raskin RE and Meyer DJ (2ed): Canine and Feline Cytology. A Color Atlas and Interpretation Guide, Missouri. Saunders, 2010; 123-169

 

Jefferies R, Vrhovec RG, Wallner N and Catalan DR: Aelurostrongylus abstrusus and Troglostrongylus spp. (Nematoda Metastrongyloidea) infections in cats inhabiting Ibiza, Spain 2010. Vet. Parasitol; 173:344–348

 

Lacorcia L, Gasser RB, Anderson GA and Beveridge I: Comparison of bronchoalveolar lavage fluid examination and other diagnostic techniques with the Baermann technique for detection of naturally occurring Aelurostrongylus abstrusus infection in cats. J. Am. Vet. Med. Assoc 2009; 235: 43–49

 

Traversa D and Di Cesare: Feline lungworms: what a dilemma. Trends in Parasitology 2012; September Vol. 29(9)

 

Traversa D, Di Cesare A and Conboy G: Canine and feline cardiopulmonary nematodes in Europe: emerging and underestimated. Parasit Vectors 2010; 3:62–84