Show Notes
Unleashed: The Dawn of the Leishmania Chapter 1: The Attack of the Sandfly 3.17 Sue introduces the topic of leishmaniasis, and Christian describes leishmaniasis as a multisystemic disease affecting humans and animals, primarily dogs. He notes its prevalence in regions like the Mediterranean and its expansion due to climate change and imported infected dogs. 5.19 Sue questions whether leishmaniasis occurs naturally in the UK or is solely imported. Christian mentions reported cases in the UK, suggesting transmission via infected phlebotomine flies brought back by travelers from endemic regions. The conversation shifts to the sandfly vector responsible for transmitting leishmaniasis. Christian describes the sandfly as small, silent, and potentially painless, emphasizing its absence in the UK but the possibility of migration due to global warming. Christian advises against using repellents on dogs in the UK due to environmental concerns but stresses the importance of monitoring the situation, given he acknowledges the likelihood of sandflies reaching the UK in the future. 7.27 John queries if leishmaniasis can be transmitted by other vectors like fleas. Christian affirms that sandflies are the primary vector for the disease, although other potential vectors are suspected but not proven. John then asks if humans can contract the disease from infected dogs. Christian explains that with the vector absent in the UK, human transmission from dogs is unlikely. However, he emphasizes the importance of isolating positive dogs to prevent transmission through blood transfusion. Chapter 2: The Haunting Symptoms and Diagnosis 9.11 The conversation then transitions to the clinical signs of leishmaniasis. Christian describes typical systemic symptoms such as anorexia, weight loss, lethargy, and mucous membrane pallor, along with some less common signs like polyuria and polydipsia. Christian also discusses characteristic skin lesions, including non-pruritic exfoliative dermatitis and erosive lesions. Sue adds her observations about the scaly appearance of affected dogs without itchiness, contrasting it with parasitic skin conditions. Christian concludes by stressing the importance of diagnostic assistance in accurately identifying the disease, especially considering its varied clinical presentations. 12.09 Sue brings up how leishmaniasis can affect nails, prompting Christian to elaborate on what clinicians might observe. He describes nails that grow unusually long and fast, resembling talons rather than being deformed. Christian notes that this sign is relatively rare in his experience, with scaly dermatitis or ulcerative dermatitis being more common presentations. 13.11 Sue then queries whether certain clinical presentations carry a better prognosis than others. Christian explains that prognosis depends on the severity of internal organ involvement, particularly kidney disease. The disease originates from the skin but can affect various body parts due to the immune system's reaction. 14.12 John asks how general clinicians diagnose it. Christian outlines that diagnosis relies on compatible clinical signs and specific clinical pathologies, notably anemia and changes in protein levels. While general practitioners can conduct serological tests, more specialized examinations may require referral to a laboratory. Christian emphasizes the importance of considering travel history and ruling out other conditions before treatment initiation. 16.40 Sue raises the issue of screening for leishmaniasis in dogs rescued from abroad, inquiring about the incubation period and when to start screening. Christian explains that the incubation period varies greatly, suggesting performing a quantitative serological test six months after returning from an endemic area. If positive, measures like using repellent and excluding the dog from blood transfusion banks are advised. Sue seeks more detail on the blood tests, and Christian elaborates on measuring the a
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CHAPTER 1 – Rosanna’s 2 Pennies Worth This month, Sue, John and Paul welcome Rosanna Marsella to the platform - Diplomate of the American College of Veterinary Dermatology and Professor at the University of Florida. 03:57 – John invites Rosanna to introduce herself. Thirty years as a veterinary dermatologist at the University of Florida, teaching, researching and treating small-animal allergy alongside some large-animal work; Florida's climate means plenty of infections. 04:42 – John asks how she'd categorise pyoderma. Rosanna explains it's classified by depth: surface pyoderma (often the "hot spot"), superficial pyoderma (essentially bacterial folliculitis), and deep pyoderma, where infection breaches the follicle wall into the dermis (furunculosis). 05:35 – Sue asks how dysbiosis differs from surface pyoderma. Allergic dogs already have reduced microbiome diversity, which shifts sharply toward Staphylococcus during a flare; dysbiosis is that pre-pustular shift, while surface pyoderma is the acute inflammatory skin-barrier damage that follows. 07:45 – Sue asks what AMD looks like clinically. Rosanna describes the classic picture: thick-coated dogs developing intensely pruritic, erosive lesions almost overnight on the face, rump or hips, driven by an acute trigger plus moisture trapped against the skin. 09:01 – John asks how important it is to find the trigger rather than just treat the lesion. Miss it, Rosanna says, and the dog either won't fully respond or will relapse. 09:54 – John runs through the usual suspects - fleas, allergic skin disease, ear disease, trapped moisture, pain, boredom. Rosanna splits these into predisposing factors (thick coat, heat, humidity, swimming) and primary triggers, ranking fleas top: an oral flea product still needs the flea to bite before it works, so a flea-allergic dog may also need a repellent. 13:37 – Sue asks whether lesion distribution helps distinguish flea-driven AMD from other allergies. Rosanna's rule of thumb: the back half of the body is fleas until proven otherwise; facial lesions warrant a work-up for pollen allergy or Malassezia otitis, both intensely itchy in their own right. 17:07 – John asks Sue whether "fleas first" holds in the UK climate too. Sue agrees fleas should be ruled out in every case, even with fast-acting isoxazoline parasiticides on board. CHAPTER 2 – More Than Skin Deep
In this month's episode, Sue, John and Paul welcome Professor & Chief of Service (Dermatology) at UC Davis, Stephen D White to the podcast. Chapter 1: Sheep Skin Detectives (03:09) Sue sets the scope: primary-care perspective rather than rare autoimmune disease. Stephen confirms autoimmune skin disease is vanishingly rare in sheep (pemphigus foliaceus essentially unreported, bar one Barbary sheep case in a zoo). (06:10) Sue asks whether clinical distribution helps localise the cause in a pruritic sheep the way it does in a dog or cat. Stephen explains it's less reliable — thick wool can mask hair loss even with significant pruritus, though rubbing behaviour is usually evident. Lice are visible with a hand lens; mites are not. (08:07) Question on empirical response to treatment. Stephen notes lice usually respond well to licensed ectoparasiticides (mainly avermectins); isoxazolines are unlicensed in ruminants and unreported in sheep specifically (though used in camelids, and anecdotally a bighorn sheep). Repeat treatment at 2–4 weeks is usually needed to catch hatching eggs. Chapter 2: Suspect Number 1 - Ectoparasites (11:30) John asks for top differentials in a pruritic sheep, Stephen answers: “ectoparasites, ectoparasites, and ectoparasites” — mites, lice and sheep keds (which are insects, not mites). He stresses checking in-contact sheep, since one animal may be subclinical while another is severely affected. (13:49) Sue asks why would a referral centre see an ectoparasite case at all? Stephen: usually a failed or incomplete owner-applied treatment, or a backyard sheep simply not monitored closely enough for early signs. (15:29) On technique: always scrape if pruritic, using a medical-grade spatula rather than a blade (sheep are skittish; a slip with a blade causes injury). An otoscope with the cone removed doubles as a magnifier and light source. Dermatophytosis should also be considered — often presenting as facial alopecia rather than fleece loss — and can coexist with ectoparasitism. (15:09) John ask about photosensitisation. Stephen distinguishes hepatogenous causes (impaired phylloerythrin metabolism from hepatotoxic plants, or a genetic defect in Corriedale lambs) from primary photodynamic plant ingestion (e.g. St John's Wort). Lesions favour the head and distal limbs. Flock-wide cases point to an environmental cause (send hay/pasture samples to the local extension lab); idiosyncratic reactions (as seen with clover in horses) may occur but are poorly documented in ruminants. Chapter 3: Dermatological Movie Stars (26:48) John introduces orf, referencing its cameo in Sheep Detectives. Stephen describes it as a parapoxvirus infection, usually self-limiting, but causing anorexia through oral pain — a problem in production settings. A non-resolving “super orf” form causes severe weight loss. Stephen shares data from the retrospective study: of ten orf-affected sheep, five were euthanised, due to generalised cutaneous lesions or concurrent Corynebacterium pseudotuberculosis abscesses — evidence that orf can significantly compromise immune function. One case of orf-associated facial alopecia resolved fully once the virus cleared. (31:07) On zoonotic risk and management: gloves are essential when handling any crusting lesion in sheep or goats. Management includes moistening hay to ease painful feeding, antibiotics for secondary bacterial infection, and parenteral treatment or stomach tubing in severe anorexia. (33:17) Sue asks about bacterial skin disease. Stephen identifies C. pseudotuberculosis and staphylococcal abscesses as the main presentations — often large, anywhere on the body, commonly peri udder in females. Internal abscessation (lungs, liver) is a key concern; aspirated purulent masses warrant involving a large-animal colleague, with caution against environmental contamination during drainage. Dermatophilosis is discussed as globally widespread and rain-associated, presenting dorsally, or interdigi
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