CASE NOTES

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Lumpy skin disease (LSD) ruled out in a case of Actinobacillus dermatitis in a young steer

Victoria Ludlow, Willunga & Aldinga Veterinary Services, Jeremy Rogers, Senior Veterinary Officer, PIRSA, Murray Bridge, SA and Graeme Knowles, Specialist Veterinary Anatomic Pathologist, Gribbles Veterinary Pathology

Posted Flock and Herd June 2024

Introduction

In November 2023, one of the authors (VL) was called to a property on the Fleurieu Peninsula to inspect a steer with skin lesions, predominantly on the left side. The raised lesions were unusual in appearance and as lumpy skin disease (LSD) was considered a differential diagnosis, the case was reported to the Department of Primary Industries and Regions, South Australia (PIRSA). Samples were collected for analysis. LSD was ruled out and a diagnosis of Actinobacillus dermatitis was made. The cutaneous form of actinobacillosis has rarely been reported in Australian cattle.

History

The 12-month-old Speckle Park steer was born on the property. Skin lesions were noticed about two weeks prior to the visit and had been slowly increasing in size. The lesions were at multiple sites on the body, but mainly the left side. The steer mixed with several other cattle on the property, however no other animals showed similar clinical signs. The cattle had not been injected recently and there had been no new arrivals onto the property. The owner had treated the lesions with topical antibacterial wound spray.

Examination

The lumps were raised and somewhat circular in appearance. The predominant lesion was located just cranial to the left forelimb shoulder, in the prescapular region. It measured approximately 10cm x 15cm x 3cm. It was multi-lobulated and had a crusted, hairless surface (Figure 1a). A similar but smaller lesion measuring approximately 5cm was present on the caudal abdomen, just cranial to the left hindlimb thigh, in the prefemoral region (Figure 1b). A few less obvious lesions were also present on the medial aspect of the left hindlimb thigh.

Figure 1. Initial presentation of lesions prior to veterinary treatment. Prescapular lesion (a) and prefemoral lesion (b). Note that the blue-tinge colour was from the antibiotic spray.

When pressure was applied, a cream-coloured and thick exudate was discharged from the prescapular lesion (Figure 2). After removing the external crust, the lesions had a granulomatous appearance. The underlying tissue was dense and haemorrhagic (Figure 3).

Figure 2. Prescapular lesion with thick, cream-coloured discharge

Figure 3. Prescapular lesion once scab was removed. Underlying tissue had a granulomatous appearance and was very haemorrhagic.

All other physical exam parameters were within normal limits.

Differential Diagnoses

A number of conditions were considered as differentials including ulcerative lymphangitis, actinobacillosis, actinomycosis, cutaneous lymphoma and LSD. Incisional biopsies were collected and sent for analysis.

Treatment

The steer was treated with a long-acting, intramuscular antibiotic injection (oxytetracycline), a subcutaneous anti-inflammatory injection (meloxicam) and intravenous sodium iodine at a dose of 66 mg/kg.

A second dose of sodium iodine was repeated two weeks later. Images were taken following the first (Figure 4) and six weeks after the second (Figure 5) sodium iodide treatment. There was an obvious reduction in size of the lesions following the first dose. The prescapular lesion measured approximately 6cm x 4cm x 1cm and appeared a lot less inflamed. The prefemoral lesion was no longer raised and the area had contracted down significantly. Six weeks after the second treatment the prescapular lesion has further reduced in size to approximately 3cm x 1.5cm x 1cm and the prefemoral lesion had completely resolved.

Figure 4. Prescapular (a) and prefemoral (b) lesions following treatment with intravenous sodium iodide and intramuscular, long-acting oxytetracycline

Figure 5. Prescapular (a) and prefemoral (b) lesions six weeks following the second treatment with intravenous sodium iodide

Results

Genetic testing for LSD was performed at the Australian Centre for Disease Preparedness. Lumpy skin disease virus DNA was not detected in fresh cutaneous lesions or EDTA blood and antibodies to LSD were not detected in serum.

Microbiology, microscopy and histopathology were performed at Gribbles Pathology. Bacterial cultures identified light growths of an Actinobacillus sp., Staphylococcus hyicus and other mixed organisms. Marked focal ulceration of the epithelium and abundant serocellular crust was noted. The dermal architecture had been replaced by multiple coalescing pyogranulomas with central lytic necrosis and Splendore-Hoeppli material. The lesion was summarised as dermatitis, necrotising, pyogranulomatous, moderate, multifocal, chronic with intralesional Splendore-Hoeppli.

Discussion

The steer was diagnosed with a cutaneous form of actinobacillosis. The skin lesions were caused by an Actinobacillus sp., possibly with some fungal and other bacterial co-infection. Treatment with sodium iodide, antibiotics and anti-inflammatories was effective as lesions were significantly smaller at the two-week revisit and almost completely resolved six weeks after the second dose of sodium iodide.

Actinobacillus bacteria are normal inhabitants of the oral cavity of ruminants but are known to cause opportunistic infections. Infections of the tongue (commonly referred to as 'wooden tongue'), gums and oral cavity of cattle are seen regularly in practice, often because of damage to the oral mucosa from grazing rough feed. Actinobacillus have the tendency to invade soft tissues, often spreading to regional lymph nodes of the head and neck. Infection may also extend to subcutaneous tissue and the skin, causing granulomatous ulceration. Atypical or cutaneous forms of infection are rare but have been reported in overseas cattle.^1,2,4,5 It is often a disease seen in individual animals, as in this case, however herd outbreaks have also been reported.³

Actinobacillus are not believed to survive readily in the environment so the more likely cause of infection in this case is from abrasions in the oral mucosa from rough feed or alternatively bacteria gaining entry through cows licking open skin wounds. Actinobacillosis typically responds well to sodium iodine therapy and/or long-term antimicrobial treatment and this case supports this type of treatment for cutaneous forms.

This report describes an unusual clinical case where the veterinarian worked closely with government officials to facilitate disease investigation and rule out notifiable and exotic diseases.

References

1. Caffarena RD, Rabaza A, Casaux L, Rioseco MM, Schild CO, Monesiglio C, Fraga M, Giannitti F and Riet-Correa F (2018) Natural lymphatic ("atypical") actinobacillosis in cattle caused by Actinobacillus lignieresii. Journal of Veterinary Diagnostic Investigation 2018 Mar; 30(2):218-225. doi:10.1177/1040638717742621 Epub 2017 Dec 4. PMID: 29202671; PMCID: PMC6505872
2. Cahalan SD, Sheridan L, Akers CR, Lorenz I and Cassidy J (2012) Atypical cutaneous actinobacillosis in young beef cattle Veterinary Record 2012 Oct 13; 171(15):375. doi:10.1136/vr.100906 Epub 2012 Aug 22. PMID: 22915684
3. Davies M. Two "outbreaks" of Actinobacillosis in beef cattle (2015) www.flockandherd.net.au Accessed June 2024
4. Margineda CA, Odriozola E, Moreira AR, Cantón G, Micheloud JF, Gardey P, Spetter M, and Campero CM (2013) Atypical actinobacillosis in bulls in Argentina: granulomatous dermatitis and lymphadenitis Pesquisa Veterinária Brasileira 33(1),1-4. doi.org/10.1590/S0100-736X2013000100001
5. Rebhun WC, King JM and Hillman RB (1988) Atypical actinobacillosis granulomas in cattle Cornell Veterinarian 1988 Apr; 78(2):125-30. PMID: 3371003
6. Relun A, Cesbron N, Bourdeau P, Dorso L, Brement T, Assié S, Christensen H and Guatteo R (2019) Atypical actinobacillosis affecting hind limbs and lungs in a single beef cattle herd Journal of Veterinary Internal Medicine 2019 Jan; 33(1):297-301. doi:10.1111/jvim.15387 Epub 2018 Dec 12. PMID: 30548325; PMCID: PMC6335530