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Parasite problems around the world

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08 November 2017, at 11:06a.m.

Unusual incident of ivermectin toxicosis in three adult horses

Tamara Swor and others, Texas A&M University

In a group of five adult quarter horses, three developed neurological signs about 18 hours after receiving routine anti-strongyle treatment with an ivermectin-based paste. These included depression, fore- and hind-limb ataxia, drooping of the superior and inferior lips and muscle fasciculations. 

The clinical signs became progressively worse and one horse was euthanased. But the others responded to supportive therapy with intravenous fluids and anti-inflammatory medication and on recovery there were no long-term sequelae. Analysis of the paste showedanormal ivermectin concentration of 1.87%. 

Post mortem examination of the euthanased mare showed high levels of ivermectin residues in the brain tissue. The authors note that ivermectin toxicosis is a rare event but should be considered if neurological impairment develops following anthelmintic treatment with suchaproduct. 

Journal of the American Veterinary Medical Association 235 (5): 558-562. 

Comparison of diagnostic methods for detecting Aelurostrongylus abstrusus in cats 

Lauren Lacorcia and others, University of Melbourne 

Aelurostrongylus abstrusus is a lungworm parasite of cats with a world-wide distribution, causing signs of respiratory tract disease in individuals of all ages. 

The authors compare a range of diagnostic methods for identifying the organism in the cadavers of 80 semiferal cats. These included bronchoalveolar lavage, faecal sedimentation-flotation and histological examination of lung tissue. Overall, the Baermann technique was shown to be the most sensitive test for detecting A. abstrusus and revealed a prevalence of 13.8%. 

Journal of the American Veterinary Medical Association 235 (1): 43-49. 

Oxyclozanide treatment of the rumen fluke Calicophoron daubneyi in goats 

Carine Paraud and others, French Food Safety Agency, Niort, France

The paramphistome group of flukes parasitise the rumen of domestic livestock and have a worldwide distribution. In temperate zones they normally cause relatively mild clinical signs but the growing prevalence of the organism is causing increasing concern in Europe. 

The authors investigate the efficacy of oxyclozanide at a dose of 22.5 mg/kg against experimental infections in goats of the rumen fluke Calicophoron daubneyi. The agent did not significantly affect numbers of juveniles but was highly effective against the adults. 

The Veterinary Journal 180(2), 265-267 

Haematological and biochemical changes in dogs treated against Angiostrongylus vasorum 

Jakob Willesen and others, University of Copenhagen

Angiostrongylus vasorum is a small nematode causing verminous pneumonia in dogs and can be fatal if untreated. The authors assess the changes in laboratory findings in 48 dogs with natural infections before and after treatment with imidacloprid/moxidectin or fenbendazole. Their findings show that even in dogs with unremarkable blood results, the parasite may cause a low grade inflammatory response, which is only apparent when white blood cell levels fall after treatment. Infestations may also cause a decrease in serum fructosamine. 

The Veterinary Journal 180 (1): 106-111. 

Tritrichomonas foetus infection in cats with diarrhoea in a rescue colony 

Malcolm Holliday and others, Rifugio per Gatti ‘Cinni’, Arezzo, Italy

Tritrichomonas foetus is a protozoan parasite that is a cause of prolonged and intractable diarrhoea in cats. Most reports to date have come from the USA but the organism is thought to have a wider distribution. 

The authors report the identification of T foetus in samples from 24 out of 74 individuals at an Italian cat shelter experiencing problems with chronic bowel disease. The organism was identified by direct microscopy of faecal smears and confirmed by PCR analysis. All affected cats were non-pedigree cats over one year old. 

Journal of Feline Medicine and Surgery 11 (2): 131-134. 

Comparison of two faecal egg recovery and larval cultures in detecting small strongyles 

Thomas Bello and Tammy Allen, Sandhill Equine Center, Southern Pines, North Carolina

Faecal egg recovery tests are vital in monitoring the development of anthelmintic resistance in horses. The authors compare the results of two different techniques with larval culture methods on faecal samples from 101 horses. Their findings indicate that the centrifugal flotation method was consistently superior to the McMaster technique especially at low faecal egg numbers.Acombination of centrifugal flotation and larval culture may provide the most accurate evaluation of anthelmintic efficacy on equine units. 

American Journal of Veterinary Research 70 (5): 571-573. 

Worm infestations in high and low bodyweight merino ewes 

John Larsen and Norman Anderson, University of Melbourne 

Among the reasons for low bodyweight in ewes,a higher worm burden or a greater susceptibility to the effects of an infestation could be significant factors. The authors compared faecal egg counts from the highest and lowest bodyweight quartiles in groups of two-year-old merino ewes. There were no consistent differences in the egg counts from the two groups during winter or spring but there was a higher incidence of breech soiling in the low bodyweight ewes and these individuals successfully reared lower numbers of lambs. 

Australian Veterinary Journal 87 (3): 102- 109. 

Long term efficacy of ivermectin and moxidectin in winter housed horses 

Johanne Elsener and Alain Villeneuve, University of Montreal 

Canadian horses are usually given anthelmintic treatment immediately before they enter winter housing. The efficacy of such treatment against inhibited larva will depend on the agent used. The authors compared the effects of ivermectin and moxidectin treatments on the spring rise of faecal egg counts. Both agents reduced faecal egg counts to zero three weeks after treatment but at five months post treatment, faecal egg counts were higher in the ivermectin-treated group due to the activation of inhibited larvae. 

Canadian Veterinary Journal 50 (5): 486- 490.