Type 2 diabetes mellitus with pancreatic beta cell dysfunction in 3 horses confirmed with minimal model analysis.

REASONS FOR PERFORMING STUDY: Type 2 diabetes mellitus (T2DM) is diagnosed rarely in equine practice although it may be under-recognised. A greater awareness of the condition and therapeutic considerations would be to the benefit of such cases presenting in practice. More investigation into the pharmacological management of these cases is needed. OBJECTIVES: Three cases of diabetes mellitus were investigated using a specific test for insulin sensitivity and pancreatic beta cell function in order to define accurately and characterise the existence of T2DM in all 3 subjects. METHODS: The insulin-modified frequently sampled i.v. glucose tolerance test was performed in each case and the data so obtained were subject to minimal model analysis of insulin-glucose dynamics. Cases were then monitored following treatment using a combination of dietary modification, metformin, glibenclamide and pergolide. RESULTS: Marked insulin resistance was identified in each case and, furthermore, severe pancreatic beta cell dysfunction was present therefore classifying each case as end stage T2DM. Treatment was nevertheless associated with restoration of normoglycaemia in all cases. CONCLUSIONS: T2DM in horses may be more common than generally considered.In some cases individuals may respond to therapy aimed at restoring insulin sensitivity and pancreatic function. Drugs used in other species for the treatment of T2DM have not yet been adequately tested in horses. POTENTIAL RELEVANCE: T2DM should be considered as an important differential diagnosis in mature to elderly horses and ponies suffering from weight loss, polydipsia and polyuria. Clinicians should be encouraged to offer treatment and management advice when such cases are encountered.

Comparative study of doramectin and fipronil in the treatment of equine chorioptic mange.

In equids, chorioptic mange is a common dermatitis for which there are no licensed medications in the uk. Doramectin and fipronil are licensed for the control of ectoparasites in other species and were evaluated for the treatment of 17 cases of chorioptic mange in 13 equids. Equids were included if clinical findings were indicative of chorioptic mange, chorioptes mites were positively identified and concurrent disease that could affect response to disease was not evident. A random number table was used to allocate subjects to receive doramectin (group D, eight animals) or fipronil (group F, nine animals). Each of the horses in group D were given 0.3 mg/kg doramectin (Dectomax; Pfizer) on two occasions 14 days apart by subcutaneous injection. All limbs of the horses in group F were sprayed with fipronil 0.25 per cent solution (Frontline; Merial) to the level of the stifles and elbows. Both groups were examined on the day of treatment and 14 and 28 days later to assess the behavioural signs of pruritus and the severity of the dermatological lesions. Acetate tape impressions were collected from the distal limbs and the degree of mite infestation was assessed. By day 28 there were no behavioural signs of chorioptic mange in any of the animals, and there were significant reductions in the numbers of mites in both groups. However, there were no significant reductions in the mean lesion score in either group. There was no significant difference between the effectiveness of the two treatments.