Veterinary Services

Nutritional and metabolic disorders

Three lambs died from a group of 160 on a Dumfriesshire holding. Others were described as ill-thriven. Both lambs submitted for necropsy were thin and showed evidence of scouring and anaemia. Gut washes revealed moderate numbers of Teladorsagia and trichostrongyle worms. However analysis of liver samples identified copper levels of 29 and 25 umol/kg respectively (normal range 314-7850umol/kg) and vitamin B12 of less than 0.1ug/g WM in each case (normal range >0.19ug/g WM). The SAC advised supplementation with both copper and cobalt.

Parasitic diseases

The number of outbreaks of parasitic gastroenteritis (PGE) in lambs has continued to increase from the levels reported last month (Veterinary Record, 161, (16), pages 543-546). Submission of diagnostic faecal samples from weaned lowground lambs with a history of ill-thrift and routine monitoring of bulk samples from lambs confirmed parasitic gastroenteritis on the basis of elevated worm egg counts. Aberdeen received samples from a group of six-month-old mule lambs that showed severe scour and ill thrift, despite having been wormed two weeks previously. Two pooled faecal samples showed worm egg counts of 3,400 and 27,300 strongyle eggs per gram. The lambs were then dosed with fenbendazole, but less than three weeks later the worm egg count from another pooled sample remained high at 1,850 strongyle eggs per gram. These results are consistent with resistance to benzimidazole wormers.

Faecal samples were collected on two farms in the Dumfries area to investigate ill thrift and scour. In both cases the worm egg counts were low while the coccidial counts ranged from 2,100 to 4,500. Coccidiosis is not usually a cause of ill thrift or disease in lambs older than eight weeks of age, but in this case the clients requested that coccidial speciation was carried out. However, only 12 per cent and 25 per cent of the species present were recognised pathogens, confirming that this was not the problem.

Musculo-Skeletal conditions

A group of 450 Cheviot ewes with lambs at foot were gathered off the hill for shearing and worming respectively. Weather conditions delayed shearing for three days. When the work began, three of the lambs were noted to be sternally recumbent. As shedding of the lambs from the ewes proceeded, a further 15 lambs began to pant and lie down. Subcutaneous calcium was given to the affected individuals. Some got to their feet within five minutes but they were weak and ataxic for a short time. Others remained recumbent several hours later. The following morning one lamb was dead and three were recumbent. Two laterally recumbent lambs were submitted for postmortem examination. When supported, one lamb tried to propel itself forwards while the other knuckled on all four feet. Withdrawal reflexes were difficult to elicit. No gross changes detected at necropsy and serum calcium, GSH-PX and vitamin E levels were normal. Serum creatinine kinase activity were significantly elevated at 4,960 and 2,457iu/l respectively (normal range <50 iu/l). Histopathology of the skeletal muscles showed dramatic, acute myofibril degeneration with no reactive changes. The heart, diaphragm and intercostal muscles were normal. The SAC proposed a diagnosis of capture myopathy related to stress but was unable to explain the delay in onset of three days after gathering from the hill.

Nervous system disorders

Fifteen deaths were reported amongst homebred ewes and lambs from an Argyllshire farm. Clinically affected animals were reported to be "covered in ticks" and were found in lateral recumbency and hyperaesthetic. A diagnosis of louping-ill was made on the basis of circulating IgM antibodies to the virus. A similar diagnosis was made on the basis of serology in a lamb exhibiting nervous signs on the Outer Hebrides.

A three-year-old Texel ram suspected of being a victim of bullying by other rams was submitted for postmortem examination with a history of ataxia, followed by recumbency and death. A smooth pale circular lesion approximately four millimetres in diameter was detected between the sixth and seventh vertebrae, with apparent compression of the spinal cord. Histopathological examination of the affected area of the cervical spinal cord revealed spongy change, swollen axons with intra-myelinic oedema, intra-cytoplasmic neuronal vacuolation and early neuronal chromatolysis with peri-neuronal tags. The offending lesion appeared to be a fatty nodule or polyp. This condition described as cervical myelopathy or "wobbler syndrome" was first reported in 2005 (Penny and others, Veterinary Record 156, 327). Subsequent publications have suggested a particular propensity to the condition amongst Beltex and Texel shearling rams and a hereditary component of the condition has been suggested.

A four-month-old Scottish Blackface lamb which was said to have been weak and unsteady for two months was euthanased and submitted for postmortem examination. Eight to 10 others within the same group were said to be similarly affected. At necropsy the lamb was in good bodily condition and no gross abnormalities were detected. The liver copper level was significantly low at 141 umol/kg DM (reference range 314 to 7850 umol/kg DM) and a provisional diagnosis of swayback was made. Histological examination of the spinal cord showed multiple chromatolytic neurones confirming the diagnosis.

Skin diseases

A Suffolk ewe had pruritic dermatitis around the eyes, on both pinnae and affecting the ventrum. It was the only animal in the flock affected. Treatments with a permethrin pour-on and an avermectin drug were ineffective. Skin scrapes were negative for lice and mites. A midge allergy was suspected and histopathology was carried out on a skin biopsy changes were consistent with Culicoides spp. hypersensitivity.