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Journal of Small Animal Practice Vol 50 December 2009 2009 British Small Animal Veterinary Association 667

CASE REPORT

Ocular dirofilariosis by Dirofilariaimmitisin a dog: first case report from

Europe

INTRODUCTION

Canine vectorborne diseases are widespreadaround the world and represent a diagnos-tic challenge because of their wide range ofclinical signs (Otranto and others 2009b).Some vectorborne pathogens (for example,Dirofilaria immitis, Thelazia callipaedaandLeishmania infantum) can cause a variety ofocular manifestations in dogs (Komnenou

and Koutinas 2007). Ocular dirofilariosiscaused by D. immitis has been reportedin highly endemic areas such as Australia(Lavers and others 1969, Spratt and oth-ers 1971, Thornton 1978) and the UnitedStates (Eberhard and others 1977, Guter-bock and others 1981, Metcalf and others1982, Miller and Cooper 1987, Carastroand others 1992).

Dirofilaria immitis can cause a severecardio-pulmonary disease in dogs andcats and pulmonary dirofilariosis is also a

rare zoonosis (McCall and others 2008).Dirofilaria immitis is endemic in south-ern Europe and a number of reports haveshown its recent spread to northern and

north-eastern countries (Genchi and oth-ers 2009). In Italy, D. immitis is histori-cally endemic in northern regions of thecountry (Genchi and others 2005), witha prevalence ranging from 22 to 80 percent in dogs not treated with preventivedrugs (Genchi and others 2001). How-ever, new foci of D. immitishave recentlybeen detected in southern Italy (Apulia

and Calabria regions), showing the spreadof this pathogen in this country (Otrantoand others 2009a). This case reports anunusual case of ocular dirofilariosis in adog from southern Italy.

CASE HISTORY

A five-year-old, entire female mixed-breeddog was presented to a private veterinaryclinic in Lecce (Apulia region) with a his-

tory of ocular opacity. On 17 December2008, the dog, which had not previouslybeen treated with microfilaricidal drugs,

was referred to the Veterinary TeachingHospital of the University of Bari. Onclinical examination, corneal oedema(Fig 1) and episcleral hyperaemia in theleft eye were noticed. The ophthalmologi-cal examination revealed a free-swimmingnematode in the anterior chamber of theleft eye. Ethylenediaminetetraacetic acid(EDTA) blood samples were collected andevaluated for the presence of microfilariae

by a modified Knott method (Newton andWright 1956). Additionally, a serum sam-ple was tested for D. immitisadult antigensusing a commercial ELISA (PetChekHTWM PF Canine Heartworm Anti-gen Test Kit; IDEXX). No microfilariaeor heartworm antigens were detected.Haematological analysis revealed only amild anaemia (red blood cells, 514 x 106/l; haemoglobin, 118 g/dl; haematocrit,317 per cent; eosinophil counts werenormal).

Due to the size of the nematode and therisk of sequelae associated with its phagocy-tosis within the anterior chamber, surgery

was recommended. After sedation with

A five-year-old, entire female mixed-breed dog was presented with

corneal oedema and episcleral hyperaemia in the left eye. The

ophthalmological examination revealed the presence of a free-

swimming nematode in the anterior chamber. Circulating microfi-

lariae were not observed by a modified Knott test nor were adult

antigens detected in serum by a commercial ELISA. The parasite

was surgically removed from the dogs eye, but its anterior endwas damaged during the surgery. Based on the morphology of the

posterior end, the nematode was preliminarily identified as a male

Dirofilaria immitis. The species identification was confirmed by

PCR amplification and sequencing of the mitochondrial coxIand

12S rDNA genes, using a DNA barcoding approach. Although other

cases of ocular dirofilariosis by D. immitishave been previously

recorded in Australia and the United States, the case reported

herein is the first in a dog from Europe.

F. DANTAS-TORRES, R. P. LIA, M. BARBUTO*,

M. CASIRAGHI*, A. CROVACE,

L. CALIGIANI, C. GENCHI ANDD. OTRANTO

Journal of Small Animal Practice(2009)50, 667669DOI: 10.1111/j.1748-5827.2009.00846.x

Accepted: 1 August 2009

Prof D. Otranto Dipartimento di Sanit Pubblica

e Zootecnia, Universit degli Studi di Bari,

70010 Bari, Italy

*Dipartimento di Biotecnologie e Bioscienze,

Universit degli Studi di Milano-Bicocca, 20126

Milano, Italy

Dipartimento delle Emergenze e dei Trapianti

di Organo, Universit degli Studi di Bari, 70010

Bari, Italy

Medico veterinario, libero professionista,

Lecce, Italy

Dipartimento di Patologia Animale, Igiene e

Sanit Pubblica Veterinaria, Universit degli Studi

di Milano, 20133 Milano, Italy

http://www.bsava.com/

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F. Dantas-Torres and others

668 Journal of Small Animal Practice Vol 50 December 2009 2009 British Small Animal Veterinary Association

acepromazine (2 mg/kg, IM), the eye wasclipped and prepared for surgery. Generalanaesthesia was induced with propofol (5mg/kg, IV) and maintained with isofluranein oxygen. The cornea was incised with acrescent Beaver corneal knife and the ante-rior chamber of the eye flushed with ster-

ile saline solution to float the nematode.A nematode (Fig 2) was retrieved from thedogs eye, but the anterior end of the para-site was damaged during its removal. Thedog recovered without complications afterthe surgery.

The remaining part of the parasite meas-ured 229 mm in length and had a maxi-mum diameter of 023 mm. The size (longspicule 035 mm and short spicule 019mm) and the morphology of spicules andthe number of caudal papillae (that is, fourpairs of pre-anal papillae and one pair ofpost-anal papillae) were suggestive of a maleD. immitis, as reported by Orihel (1961).

To confirm the species, a DNA barcod-ing approach was used. A piece (~2 mm) ofthe parasite was used for DNA extractionand then the coxIand 12S rDNA genes wereamplified and sequenced as described else-

where (Casiraghi and others 2004, 2006).The sequences obtained have been depos-ited in the EMBL Nucleotide SequenceDatabase (accession numbers FN391553and FN391554). The sequence analysis

showed a homology of 100 per cent with D.immitiscoxIand 12S rDNA gene sequencesdeposited in GenBank (accession numbersEU169124 and EU182327).

DISCUSSION

Surgical removal is the treatment of choicefor intraocular dirofilariosis in dogs (Kom-nenou and Koutinas 2007), the progno-sis depending on the severity of oculardamage and on the successful removal

FIG 2. Male Dirofilaria immitis. (a) macroscopic view (Bar = 1 mm). (b) damaged anterior end

(arrow) (Bar = 60 m). (c) short (white arrow) and long (black arrow) spicules (Bar = 75 m). (d)

caudal papillae (Bar = 75 m)

FIG 1. The dog showing corneal opacity on the left eye (a) and the free-swimming filarid in the anterior chamber (b). The shadow (star) observed in

the image is the ophthalmoscope

of the nematode (Carastro and others1992).

This case was quite unusual as the dogwas born and lived in southern Italy whereD. immitishas only recently been found(Otranto and others 2009a). Althoughocular examination was suggestive of ocular

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Journal of Small Animal Practice Vol 50 December 2009 2009 British Small Animal Veterinary Association 669

Ocular dirofilariosis in a dog

dirofilariosis, the absence of circulatingmicrofilariae and the negative result ofELISA for heartworm antigens made thecorrect aetiological diagnosis difficult.However, it is known that in D. immitisinfected animals antigen tests can resultfalse-negative in the presence of low heart-

worm burdens or of a single male worm(Berdoulay and others 2004).

This case report confirms the usefulnessof an integration of morphological andmolecular tools to ensure the identificationof parasites, especially of damaged speci-mens. It is also important to note that therisk finding parasites in ectopic locations

is not restricted to highly endemic areas.Thus, veterinarians working in areas whereD. immitis is spreading should includedirofilariosis in the differential diagnosisof ocular diseases in dogs, even if they arenot microfilaraemic, or seroreactive.

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