Plants that affect the skin and liver are considered together in this chapter because some plant toxins cause liver disease that results in secondary skin disease. One of the most noticeable signs indicative of an animal with liver disease is the appearance of dermatitis and hair loss affecting the white-skinned areas. Some plants contain compounds or pigments that once absorbed from the digestive system induce a direct effect on nonpigmented skin when it is exposed to light, without any effect on the liver. Other plants contain toxic alkaloids that cause irreversible liver disease resulting in a secondary photosensitization. Yet other plants have compounds that cause a skin reaction when they come in contact with skin, or they have spines or thorns that can cause mechanical injury to the skin.

A Guide to Plant Poisoning of Animals in North America

Two groups of 3 120-160-kg Holstein steers were fed a diet high in carbohydrate and low in long fiber and either with or without added sodium sulfate. Prior to and during the course of feeding the experimental diet, the concentrations of rumen hydrogen sulfide gas and rumen fluid sulfide were determined by a simple sulfide detector tube method and by sulfide-selec tive electrode, respectively. Other measurements included rumen fluid pH, blood creatine kinase, and blood sulfhemoglobin. Two of the 3 steers fed the high-sulfate diet developed signs and lesions of polioencephal omalacia. Clinical signs included episodic ataxia and blunted or absent menace reaction. Increased ruminal H2S gas concentrations occurred in all 3 steers consuming the diet with added sulfate. The onset of clinical signs coincided with the onset of elevated H 2S concentrations . These increases were 40-60 times the values measured in the steers consuming the diet without added sulfate. In contrast, increases in rumen fluid sulfide concentrations usually rose to 4 times that of control steers. The steers fed an identical diet but without added sulfate exhibited no signs or lesions of polioencephal omalacia and no elevations of sulfide in rumen gas or fluid. All steers had a modest decrease in rumen fluid pH associated with the transition to the concentrate diet. No significant changes were observed in any of the blood measurements of any of the steers. An additional pair of steers was fed the experimental diet with or without added sulfate to compare the ruminal H2S gas concentrations estimated by H2S detector tubes with those estimated by a different method of analysis utilizing charcoal trapping of H 2S, conversion to sulfate, and measurement of the sulfate. Both methods yielded comparable estimates of H 2S concentration. Overall, these data indicate that changes in rumen gas cap H2S concentrations are larger than changes in rumen fluid sulfide concentration and that estimation of rumen gas cap H2S concentration may be a practical approach to detecting pathologic increases in ruminal H2S gas. This simple, rapid, minimally invasive method should be useful for estimating the H 2S content of ruminal gas under field conditions.

https://journals.sagepub.com/doi/pdf/10.1177/104063879700900113

In Vivo Indicators of Pathologic Ruminal Sulfide Production in Steers with Diet-Induced Polioencephalomalacia

Sulfur-related polioencephalomalacia is frequently associated with a high total sulfur intake by ruminants. The onset of clinical signs coincides with excessive ruminal sulfide production. Measurement of ruminal gas cap hydrogen sulfide makes it possible to identify cattle with potentially hazardous total sulfur intake. Evaluation of all potential sulfur sources is necessary to estimate total dietary sulfur concentration, which can lead to prevention strategies.

Update on Sulfur-Related Polioencephalomalacia

Parasitism in New World camelids (NWC), which is associated with both ecto- and endoparasites, is a major health concern throughout the world. Clinical disease has been noted as causing severe economic losses; subclinical issues have yet to be addressed. Despite the advances made in the knowledge and understanding of parasites of NWC, old parasites continue to plague producers, and new issues have arisen. This article updates information on the major ecto- and endoparasites of NWC, including diagnostic techniques and issues relative to anthelmintic resistance in nematodes.

Ecto- and endoparasites of new world camelids.

An outbreak of polioencephalomalacia affected 16 of 46 Swaledale lambs and five of 25 Scottish blackface lambs 15 to 32 days after they were introduced to an ad libitum concentrate ration containing 0.43 per cent sulphur. The clinical signs were acute and included depression, central blindness and head-pressing, but no hyperaesthesia, nystagmus, dorsiflexion of the neck or opisthotonos were observed. Treatment of the affected lambs with vitamin B1, dexamethasone and antibiotics was associated with a prolonged recovery period, though no further cases were identified after vitamin B1 had been given parenterally to all the lambs at risk.

Sulphur-induced polioencephalomalacia in lambs

In the latter part of 1991 an unusual neurological disease was recognised on several farms in England. This report describes the case histories and clinical, biochemical and pathological findings in six calves and two lambs aged from two to 44 weeks obtained from five of these farms. Laminar cerebrocortical necrosis and severe bilateral necrosis of the thalamus and/or striatum progressing to cavitation were recognised in their brains. These changes are similar to those of experimental sulphate toxicity. Morbidity rates of 16 to 48 per cent and mortality rates of 0 to 8 per cent were recorded. The affected animals did not respond to vitamin B1 treatment; the erythrocyte transketolase levels of in-contact cattle and of one untreated affected calf and one untreated lamb were within the normal range. All five farms had recently introduced a proprietary concentrate ration containing ammonium bicarbonate. After this ration was withdrawn no new cases of nervous clinical disease were observed. It is suggested that, in at least some cases, the morphology and topography of lesions may distinguish sulphate induced polioencephalomalacia from that of sporadic thiamine-dependent cerebrocortical necrosis.

Polioencephalomalacia associated with the ingestion of ammonium sulphate by sheep and cattle

SIR, — There is increasing evidence that squirrel pox disease is the principal cause of the rapid decline of the red squirrel ( Sciurus vulgaris ) in England ([Rushton and others 2006][1]). However, relatively little is known about other infectious agents that may adversely affect this endangered

Enteric adenovirus infection in a red squirrel (Sciurus vulgaris)

SEVERE intestinal disease associated with Eimeria punoensis, Eimeria lamae, Eimeria alpacae, Eimeria macusaniensis and Eimeria ivitaensis has been observed in South American camelids in the Americas and Australia (Guerrero and others 1971, Rosadio and Ameghino 1994, Cebra and others 2003, Lenghaus and others 2004, Palacios and others 2006). However, there is conflicting information about the pathogenicity of the various camelid Eimeria species. Experimental infection of one-month-old llama crias with E macusaniensis did not result in disease (Rohbeck and others 2003), whereas experimental infection of a six-month-old naive alpaca cria with E lamae resulted in haemorrhagic ileitis with diarrhoea, and death (Guerrero and others 1970). This short communication describes a case of coccidiosis in a 16-month-old, UK-born alpaca. The animal had been purchased at an auction four weeks previously, and was reported to have been found dead after a short period of restlessness. At postmortem examination, severe necrotising enteritis was observed (Fig 1). Histological examination of the small intestine detected multiple clumps of eosinophilic material on the mucosal surface, loss of enterocytes associated with large numbers of coccidial structures in the crypt epithelium, lamina propria and, less frequently, submucosa, including immature schizonts, macrogametes with up to 10 round, variably sized, eosinophilic inclusions, and pearshaped oocysts approximately 60 to 75 μm in length (Fig 2). Gram-positive, rod-shaped bacteria were present on the luminal surface. Faecal coccidial counts revealed 3450 oocysts per gram of faeces, subsequently speciated as 91 per cent E macusaniensis, 3 per cent E alpacae and 3 per cent E lamae. Clostridium perfringens α toxin was identified by ELISA in the small intestinal filtrate. The loss of architecture associated with the large numbers of coccidial structures in superficial as well as deep layers of the mucosa strongly suggested that the Eimeria species had caused disruption of the intestinal lining, predisposing to clostridial enterotoxaemia. Prompted by this confirmed case of coccidiosis in an adult alpaca, a review of Veterinary Investigation Diagnosis Analysis data and material received at Veterinary Laboratories Agency – Lasswade between 1999 and 2004 identified 54 recorded cases of coccidial infection in alpacas. Of the 35 animals where the age was recorded, six were crias less than two months of age, 14 were juveniles (two to 11 months) and 15 were adults (one year and older) (Table 1). In 19 cases where clinical signs had been recorded, they included diarrhoea in six cases, weight loss in six, death in five, nervous signs in one and sudden-onset weakness in one. Congestion of the small intestine was commonly observed, with some cases showing marked thickening of the enteric mucosa. Variable numbers of coccidial structures were seen in small intestinal tissue sections. Concomitant findings in 19 cases where details were recorded included bacterial enteritis in nine cases, hepatic lipidosis in five and paracentral necrotisVeterinary Record (2007) 160, 805-806

Coccidiosis in British alpacas (Vicugna pacos).

Botulism and Bisgaard taxon implicated in Arctic tern deaths in the UK.

SIR, — Under section 11 of the Wildlife and Countryside Act 1981 the use of any explosive, other than ammunition for a firearm, for the purpose of killing or taking any wild animal in England is prohibited unless under licence from Natural England (a non-departmental public body of defra). We wish

J. P. Duff

Papers

Polioencephalomalacia associated with the ingestion of ammonium sulphate by sheep and cattle

Enteric adenovirus infection in a red squirrel (Sciurus vulgaris)

Coccidiosis in British alpacas (Vicugna pacos).

Botulism and Bisgaard taxon implicated in Arctic tern deaths in the UK.

Deaths of wild rabbits associated with a novel method of pest control