RESUMO Objetivos

Simple SummaryProgressive retinal atrophy (PRA) in English cocker spaniels (ECSs) is associated with progressive rod–cone degeneration (prcd-PRA), an inherited autosomal recessive disease caused by the c.5G>A mutation in the progressive rod–cone degeneration (PRCD) gene. Data regarding the prevalence of the mutated allele are scarce in the global literature, and there is no study evaluating this frequency in Brazil. Therefore, the aim of this study was to evaluate the allele frequency of the c.5G>A mutation in the PRCD gene responsible for progressive retinal atrophy (prcd-PRA) in ECS dogs.AbstractProgressive retinal atrophy (PRA) due to the c.5G>A mutation in the progressive rod–cone degeneration (PRCD) gene is an important genetic disease in English cocker spaniel (ECS) dogs. Because the prevalence of this disease has not been verified in Brazil, this study aimed to evaluate the allele frequency of the c.5G>A mutation in the PRCD gene. Purified DNA from 220 ECS dogs was used for genotyping, of which 131 were registered from 18 different kennels and 89 were unregistered. A clinical eye examination was performed in 28 of the genotyped animals; 10 were homozygous mutants. DNA fragments containing the mutation region were amplified by PCR and subjected to direct genomic sequencing. The prcd-PRA allele frequency was 25.5%. Among the registered dogs, the allele frequency was 14.9%; among the dogs with no history of registration, the allele frequency was 41%. Visual impairment was observed in 80% (8/10) of the homozygous mutant animals that underwent clinical eye examination. The high mutation frequency found in this study emphasizes the importance of genotyping ECSs as an early diagnostic test, especially as part of an informed breeding program, to avoid clinical cases of PRA.

Background: Equidae nutritional change increased the frequency of diseases due to inappropriate administration and storage of rations. Although there are reports of ionophore poisoning (IP) and leukoencephalomalacia (LEM) in equidae from Brazil, the concurrent occurrence of both diseases by the same contaminated commercial ration is unprecedented. Therefore, the present paper aims to describe the epidemiological, clinical, laboratorial and pathological findings of concurrent IP and LEM outbreaks in horses.Cases: Eleven farmers from seven different locations in Distrito Federal, Midwestern Brazil, reported sudden clinical signs in 27 horses after the ingestion of commercial pelleted ration. During the farm visits, it was found that the ration brand and batches were identical, and macroscopic evaluation revealed no abnormalities. Eight horses were clinically evaluated and presented hyporexia, apathy, hypermetria, ataxia, dehydration, dyspnea, tongue hypotonia, muscle tremors, tachycardia, facial hypoalgesia, dysphagia, and sporadic or permanent recumbence. Laboratorial changes were restricted to creatine phosphokinase (mean: 1,573.4 ± 16.9 IU/L) and gammaglutamyl transferase (mean: 34.85 ± 29.14 IU/L) serum increases. Pathological evaluation has performed in eight horses presenting pallor and whitish striations in the gluteal, longissimus dorsi, femoral quadriceps muscles and myocardium, varying from mild to moderate. One horse also showed a soft and yellowish focal area on the right temporal lobe white matter. Microscopically, alterations in skeletal and cardiac muscle tissues included striated muscle fibers and cardiomyocytes segmental necrosis, characterized by sarcoplasmic fragmentation with clusters of eosinophilic debris, cellular retraction and hypereosinophilia. Histological alterations in the central nervous system of one horse were characteristic of LEM. Ration samples analysis revealed the presence of salinomycin (2,384.91 ± 100.7 ppm), narasin (144.15 ± 7.75 ppm) and fumonisins (0.87 to 4.09 ppm). Eight hospitalized horses were submitted to clinical therapy (gastric lavage and application of activated charcoal; fluid-electrolyte imbalance correction, intravenous dimethylsulfoxide, tocopherol and selenium supplementation). Four (50%) horses had permanent sequelae (muscle weakness and mild ataxia), two (25%) recovered without sequelae, and two (25%) were euthanized due to inability to stand and poor prognosis. Considering the total number of affected horses, mortality rate reached 59.25% (16/27).Discussion: Usually ionophores are safely used in livestock and bird production at the recommended doses. However, horses are among the most susceptible species and do not tolerate any exposure to the substance. The outbreaks herein occurred due accidental ionophore contamination of commercial ration at the industry probably by manufacturing process technical failures. Similarly, fumonisins contamination may be caused by feedstock inadequate storage at the industry, or improper ration storage in the farms. The suspicion of two concurrent diseases (IP and LEM) in the horses of these outbreaks was confirmed through the association of epidemiology, clinical signs, pathological findings and measurement of ionophores and fumonisins in the commercial ration. We reiterate the difficulty in diagnosing associated clinical syndromes, especially when high-lethality diseases are involved.

Hereditary nephropathy is a primary progressive glomerular disease in dogs associated with the c.115A>T mutation in the COL4A4 gene in English cocker spaniel (ECS) dogs. The disease is inherited in an autosomal recessive manner. Hereditary nephropathy has been described in this breed since the late 1940s. To date, there are no data on the prevalence of this disease in Brazil, so the aim of this study was to evaluate the allelic frequency of this mutation in ECS dogs in this country. The DNA samples were purified from blood samples or buccal swabs from 221 ECS dogs. Fragments of the DNA containing the mutation were amplified by PCR and submitted to direct gene sequencing. The allele frequency of the mutation was 0.9%. The presence of the mutation in the ECS dog population in Brazil reveals the importance of performing the genotyping tests in these dogs as a method of diagnosing the disease and identifying heterozygous animals, aiming to reduce clinical cases of disease through mating.