Cutaneous Habronemiasis in a Dog - Veterinary Pathology

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Cutaneous Habronemiasis in a Dog 

T. P. Sanderson and Y. Niyo 

Vet Pathol 1990 27: 208 

DOI: 10.1177/030098589002700312 

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Vet. Pathol. 27:208-209 (1990) 

Key words: Dog; habronemiasis; parasite; skin. 

Cutaneous Habronemiasis in a Dog 

Cutaneous habronemiasis (summer sores), a common condition 

in horses, is characterized by ulcerative, non-healing 

skin lesions and the formation of exuberant granulation tis- 

~ue.~.6.~.9 It is caused by aberrant intradermal migration by 

third-stage larvae (juveniles) of equine spiruroid stomach 

worms, Habronema musca, Habronema microstoma, and 

Draschia megastoma. 1,4,6~10 The normal life cycle of these 

nematodes involves development into the infective thirdstage 

larvae in a muscid intermediate host.4 Infective larvae 

are deposited by the adult fly on the mouth and lips of horses 

and are then swallowed and mature to adults in the stomach. 

Cutaneous infections occur when infective larvae are deposited 

by flies feeding in moist areas or open wounds instead 

of the mouth and lips. Experimentally, it has been demonstrated 

that infective larvae can penetrate normal, intact skin.4 

Areas frequently involved include the lower limbs, medial 

canthus of the eye, the urethral process, and prepuce.’ There 

are no previous reports of this condition in other species. 

T. P. SANDERSON AND Y. NIYO 

This report describes a case of cutaneous habronemiasis in 

a dog. 

In early July, a 9-year-old, spayed female, mixed-breed 

dog was examined because of a large, ulcerated lesion on the 

face. This lesion started as a small swelling lateral to the right 

naris. During the following 2 weeks, the lesion ulcerated and 

spread to involve most of the right side of the nose and face 

rostra1 to the medial canthus of the right eye. A biopsy from 

the edge of the lesion was fixed in 10% neutral buffered for- 

malin and submitted for histopathologic evaluation. 

Histologically, the epidermis was ulcerated and overlaid 

with a thin layer of necrotic cellular debris admixed with 

neutrophils. The dermis and subcutis were markedly edem- 

atous and contained extensive infiltrates of inflammatory 

cells, predominantly eosinophils, with fewer plasma cells, 

macrophages, and lymphocytes. Variably-sized tracts of ne- 

crotic cellular debris admixed with fragmented collagen and 

large numbers of degenerate eosinophils were also present in 

Fig. 1. Dermis, dog. Note that necrotic tracts contain transverse and oblique sections of nematode larvae. HE. Bar = 

50 pm. 

Fig. 2. Dermis, dog. Transverse section. Note the shrunken degenerate nematode larva with a distinct gut and the intense 

eosinophilic inflammatory infiltrate. HE. Bar = 20 pm. 

Fig. 3. Dermis, necrotic tract, dog. The tract contains a transverse section of a nematode larva depicted in Fig. 1. Note 

the maximum diameter 41 pm, prominent longitudinal cuticular ridges (arrowheads), and a distinct gut. HE. Bar = 20 pm. 

208 


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the dermis. Transverse, oblique, and longitudinal sections of 

nematode larvae in various stages of degeneration were present 

in the centers of several of these tracts (Figs. 1, 2). The 

maximum diameter of transverse sections of these nematodes 

ranged from 38 to 43 pm. Their cuticles were thin (1- 

2 pm) with 37 to 40 fine longitudinal cuticular ridges (Fig. 

3). Intestinal structures were often poorly defined, but a gut 

was apparent in some sections (Figs. 2,3). Other microscopic 

changes included occasional small collections of large macrophages 

with abundant pale cytoplasm surrounding unidentified 

cell debris or accumulations of a homogenous eosinophilic 

substance (Splendore-Hoeppli material), multiple 

hemorrhages, mild reactive fibroplasia, and atrophy of adnexae. 

Based on size, structure, the presence of longitudinal cuticular 

ridges, and the nature of the lesion, these nematodes 

were identified as third-stage larvae of Habronema sp., the 

spiruroid stomach worm of the horse. They are similar in 

appearance to the third-stage larva of Habronema muscae. lo 

The larva of H. muscae has 40 to 42 cuticular ridges and a 

maximum diameter of 41 pm.I0 D. megastoma has a smooth 

cuticle and is slightly larger.4.10 The histologic appearance of 

the third stage larvae of H. microstoma has not been described 

in the previous literature. 

The clinical presentation and microscopic lesions of cutaneous 

habronemiasis in this dog were similar to those seen 

in horses; however, rapid proliferation of granulation tissue, 

a characteristic feature of this condition in the horse, was 

not present. Clinically, this condition must be differentiated 

from an infiltrating cutaneous neoplasm, particularly squamous 

cell carcinoma. Differential microscopic diagnoses include 

dermatitis due to other migrating nematode larvae, 

such as Ancylostoma caninum or Uncinaria stenocephala, 

the free-living saprophyte Pelodera strongyloides, Strongyloides 

stercoralis, and dermatitis associated with microfilariae 

of Dirofilaria immitis. All of these nematode larvae are considerably 

smaller and morphologically different from those 

of Habronema spp.' Canine eosinophilic granuloma should 

also be considered if nematodes are not present in the lesion.5 

Several factors may have contributed to the development 

of this condition. This dog was housed under poor sanitary 

conditions in a small shed with several heavily parasitized 

ponies. The near record high temperatures during this summer 

period may have resulted in larger and more active fly 

populations. It has been shown that skin temperatures 1-2 

C above body temperature stimulate Habronema larvae to 

activate and break out of fly mouthparts.8 Possibly this con- 

Case Reports 209 

dition resulted from an inordinately heavy exposure to in- 

fective larvae. It has been suggested that the pathogenesis of 

this condition in the horse may involve a hypersensitivity 

to larval antigens.l.2J0 

This dog responded to therapy with oral and topical fe- 

bendazole (Panacur @, Hoechst-Roussel Agri-Vet Co., Som- 

erville, NJ), broad spectrum antibiotics, and corticosteroids. 

Resolution was complete within 2 to 3 weeks. 

Acknowledgments 

The authors thank Dr. J. H. Greve for assistance with 

identification of these nematodes and for reviewing this 

manuscript. 

References 

1 Fadok VA: Parasitic skin diseases of large animals. Vet 

Clin North Am [Large Anim Pract] 6:22-24, 1984 

2 Kirkland K, Convin RM, Coffman JR: Habronemiasis 

in an Arabian stallion. Equine Pract 3:34-38, 1981 

3 Nichols RL The etiology of visceral larval migrans. 11. 

Comparative larval morphology of Ascaris lumbricoides, 

Necator americanus, Strongyloides stercoralis and Ancylostoma 

caninum. J Parasitol 42:363-399, 1956 

4 Nishiyama S: Studies on habronemiasis in horses. Bull 

Fac Agr, Kagoshima University 7:l-81, 1958 

5 Scott DW: Cutaneous eosinophilic granulomas with collagen 

degeneration in the dog. J Am Anim Hosp Assoc 

19~529-532, 1983 


vet.sagepub.com by guest on February 11, 2013 

6 Scott DW: Large Animal Dermatology, pp. 251-254. 

W. B. Saunders, Philadelphia, PA, 1988 

7 Steckel RR, Kazacos KR, Hanington DD, Thacker HL, 

Rebar AH: Equine pulmonary habronemiasis with acute 

hemolytic anemia resulting from organophosphate treat- 

ment. Equine Pract 535-39, 1983 

8 Trees AJ, May SA, Baker JB: Apparent case of equine 

cutaneous habronemiasis. Vet Rec 115: 14-1 5, 1984 

9 Vasey JR: Equine cutaneous habronemiasis. Comp Cont 

Educ 323290, 198 1 

10 Waddell AH: A survey of Habronema spp. and the iden- 

tification of third-stage larvae of Habronema megastoma 

and Habronema muscae in section. Aust Vet J 4520- 

21, 1969 

Request reprints from Dr. T. P. Sanderson, Department of 

Veterinary Pathology, College of Veterinary Medicine, Iowa 

State University, Ames, IA 5001 1 (USA).

Cutaneous Habronemiasis in a Dog - Veterinary Pathology

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