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Round-up of the recent literature on parasites

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01 August 2014, at 1:00am

Why, when and how to control liver fluke in cattle 

Andy Forbes, Green End Farm, Ware, Hertfordshire 

The liver fluke (Fasciola hepatica) is a parasitic condition of increasing economic performance for the UK livestock industry.

In cattle, flukes are unlikely to be a cause of the acute, fatal conditions seen in sheep but they may be responsible for three separate health issues: anaemia, liver damage and immunomodulation, which may affect the host response to other pathogens, such as bovine tuberculosis.

The author reviews the pathology, impact and epidemiology of fasciolosis in cattle and offers advice to bovine practitioners on practical control strategies. He notes that there is a relatively small choice of ukicidal products and several have withdrawal times that render them difficult to incorporate into routine farm management practices.

He suggests that clinicians should tailor their advice on fluke control to individual properties, taking into consideration the farmer’s objectives and culture, and the need to keep any recommended actions simple, practical and economically sound. They are also reminded of the need to incorporate fluke control within the strategy for dealing with other major ecto- and endoparasitic diseases.

Cattle Practice 21 (2): 150-156.

Common misconceptions held by clients about heartworm in cats 

Kristin MacDonald, VCA Animal Care Center, Rohnert Park, California

Many US cat owners believe that cats kept indoors will not be susceptible to heartworm infections, unaware that the mosquito vectors may readily enter the home. This and 10 other fallacies that practitioners regularly encounter were listed in a conference presentation by the author in Washington DC. She notes, for example, that many clients believe that treatment for heartworm will be the same in cats and dogs. Meanwhile, with appropriate all-year- round prophylactic treatment, the condition is also readily preventable. 

Veterinary Medicine 108 (8): 372-373.

Fungal isolates in the biological control of gastrointestinal nematodes in cattle 

Manoel Eduardo da Silva and others, Federal University of Vicosa, Brazil 

Endoparasites are a major constraint on the development of the cattle industry in semiarid areas of Brazil. Due to the problems of drug residues and increased anthelmintic resistance, the search is on for alternative worm control strategies. The authors conducted trials on the use of two fungal species, Duddingtonia agrans and Monacrosporium thaumasium, delivered twice a week in alginate pellets for controlling trichostrongylids in prepubescent ruminant cows. Treated animals produced fewer eggs per gram of faeces and there was a significant reduction in the numbers of infective larvae on the pasture.

Veterinary Research Communications 38 (2): 101-106.

Guidelines for treating lice in sheep with long coats to prevent wool damage 

Peri Lucas and Brian Horton, University of Tasmania

Lice infestations can have serious implications for wool producers because of the negative effects on bre quality and quantity. Traditionally in Australia, lice treatments are applied annually after shearing but producers are now advised to treat only when lice are detected. The authors developed guidelines for treatment based on a model of the development of wool damage in long-fleeced sheep. The model identifies the conditions under which treatment is advisable on an economic basis and the guidelines can minimise the net cost of infestation and limit unnecessary use of pesticides. 

Australian Veterinary Journal 92 (1-2): 8-14.

Field efficacy of eprinomectin against sucking lice in naturally infested donkeys 

Vincenzo Veneziano and others, University of Naples, Italy

The sucking louse Haematopinus asini is a common ectoparasite of donkeys and other equids which may cause anaemia, pruritus, loss of body condition and general debility. The authors examined the efficacy of eprinomectin, an avermectin used as a pour-on treatment for lice in cattle, to treat naturally occurring H. asini infestations in donkeys. The agent was administered at the recommended dose in cattle of 500μg/kg to 15 animals. No lice were found on examinations from seven days post- treatment to the end of the study at 56 days. There was no evidence of any adverse reactions in the animals treated. 

The Veterinary Journal 197 (2): 512-514.

Diagnosis of giant kidney worms (Dioctophyme renale) in dogs 

Sheila Rahal and others, Sau Paulo State University, Brazil

The giant kidney worm (Dioctophyme renale) is a parasitic roundworm with a global distribution infesting dogs and a range of other species, including humans. Diagnosis is usually achieved by finding ova in the urine but that only occurs when gravid female worms are present in the kidneys. The authors investigated the value of ultrasonography and computed tomography in dogs. They found that both imaging modalities were effective in detecting D. renale in the kidney but less useful in identifying parasites in the abdominal cavity. They warn that there is a risk of misinterpreting normal structures as parasites, especially within the abdomen.

Journal of the American Veterinary Medical Association 244 (5): 555-558.

In vivo effects of medicinal plants against gastrointestinal nematodes in sheep 

Mawahib Ahmed and others, University of KwaZulu-Natal, South Africa

Resistance to anthelmintic drugs has become a major problem for sheep producers across the globe. The authors investigated the effects of ethanol extracts of five plants with apparent medicinal properties: pineapples (Ananas comosus), Cape aloe (Aloe ferrox), garlic (Allium sativum), Chinese bushclover (Lespedeza cueata) and pepperbark tree (Warburgia salutaris). Administered weekly for six weeks, each agent reduced nematode egg production and infective larval yields, although there was no appreciable effect on bodyweight gain. Continued treatment with these plant extracts could greatly reduce parasite burdens and improve host health. 

Tropical Animal Health and Production 46 (2): 411-417.

Terbinafine in the treatment of intestinal Cryptococcus neoformans in the dog 

Gavin Olsen and others, Iowa State University

Cryptococcus neoformans is a fungal pathogen that causes diseases of the nasal cavity, central nervous system, skin, bone and lymph nodes in various species. It is only rarely reported as a cause of gastrointestinal disease. The authors encountered an unusual presentation in a dog with protein- losing enteropathy due to C. neoformans found primarily in the small intestine and lymph nodes. The case occurred in a 2.5-year-old intact male vizsla with persistent diarrhoea, weight loss and panhypoproteinaemia. Following surgical treatment to remove damaged sections of the small intestine, the condition was successfully treated with the fungicide terbinafine.

Journal of the American Animal Hospital Association 48 (3): 216-220. 

Kidney function in canine leishmaniasis cases following treatment 

Marco Pierantozzi and others, Pirani Veterinary Clinic, Reggio Emilia, Italy

Renal pathologies are a frequent cause of death in dogs with the zoonotic parasitic condition leishmaniasis. The authors investigated changes in renal function in dogs with leishmaniasis following treatment for four to eight weeks with meglumine antimoniate and allopurinol. Urine protein/creatinine, total protein and total globulin significantly decreased and both albumin and albumin/globulin ratio increased following treatment. They note that these results may be useful to clinicians in the clinical management of canine leishmaniasis in dogs with proteinuric chronic kidney disease. 

Journal of the American Animal Hospital Association 49 (4): 231-236.

Storage mite contamination of commercial dry dog food 

Clare Hibberson and Linda Vogelnest, University of Sydney 

Storage mites are free-living arthropods that are implicated in atopic dermatitis in humans and dogs both from unique sensitisation and from cross-reactivity with the more common dust mite antigens. The authors investigated samples from unopened packages of nine brands of commercial dried dog foods. Storage mites, identi ed as Tyrophagus putrescentiae, were visible in increasing numbers in seven of nine samples following incubation under conditions of moderate temperature and high humidity. These findings may have relevance in dealing with cases of canine atopic dermatitis. 

Australian Veterinary Journal 92 (6): 219- 224.

Pharmacokinetics of albendazole and its metabolites in laying hens 

Mariana Bistoletti and others, UNCPBA, Tandil, Argentina

Increasing problems with roundworm parasites such as Ascaridia galli are being reported in poultry housed in deep litter systems in many countries. The authors carried out a study to investigate the plasma disposition kinetics of albendazole and its main metabolites when administered orally and through a single intravenous

dose in laying hens. The study provides useful information on the pharmacokinetic behaviour of albendazole given through different administration routes. It is an essential step in evaluating the potential of this agent in controlling roundworm parasites in poultry. 

Journal of Veterinary Pharmacology and Therapeutics 36 (2): 161-168.